A hitherto unnoticed adaptive radiation: epitoniid species (Gastropoda: Epitoniidae) associated with corals (Scleractinia)

Twenty-two epitoniid species that live associated with various hard coral species are described. Three genera, viz. Epidendrium gen. nov., Epifungium gen. nov., and Surrepifungium gen. nov., and ten species are introduced as new to science, viz. Epidendrium aureum spec. nov., E. sordidum spec. nov., Epifungium adgranulosa spec. nov., E. adgravis spec. nov., E. adscabra spec. nov., E. marki spec. nov., E. nielsi spec. nov., E. pseudolochi spec. nov., E. pseudotwilae spec. nov., Surrepifungium patamakanthini spec. nov., and ‘Epitonium’ crassicostatum spec. nov. and ‘E.’ graviarmatum spec. nov. Although their identities as separate gene pools are convincingly demonstrated by molecular data, some of these species cannot be identified unequivocally on the basis of conchological characters alone. The shell shape and sculpture are only partially diagnostic because of interspecifically overlapping character states. In most of these cases, the operculum, jaw structure, radula, spawn and/or the habitat do reveal the identity. Most of these species are associated with only one or a restricted number of coral host species and have large ranges, similar to those of their hosts.


Introduction
The vernacular name "wentletraps" refers to a large group of snail species with usually slender conical shells, often ornamented with more or less prominent axial riblets. As far as known, the animals live as parasites, associated with coelenterates, either corals (Dushane, 1988a;A. Gittenberger et al., 2000), zoanthids (Robertson, 1981;Zahn, 1980) or sea anemones (den Hartog, 1987;Perron, 1978;Robertson, 1963Robertson, , 1966Robertson, , 1983aSchimek, 1986). During this research project it turned out that these associations are restricted even more than initially thought. Some conchologically variable, alleged Epitonium species, e.g. "Epitonium ulu Pilsbry, 1921", were revealed to be groups of separate species with more or less broadly overlapping shell character states. Consequently, the species described in this paper cannot conspecific specimens are figured for several species. When mean values are indicated, the extremes and the number (n) of items measured are added.
The sculpture on the shells and the opercula, the structure of the mucus threads that connect the eggcapsules, and the morphology of the radulae and jaws were investigated and photographed with a scanning electron microscope (= SEM). The complete shells were photographed with a digital camera (Fujifilm FinePix50i); those smaller than one cm, and the eggcapsules, were photographed with this camera through a microscope, without using additional devices. Most of the epitoniid snails, their egg-capsules and the coral hosts were photographed in situ with a Sea & Sea SX-1000 underwater camera. Unless stated otherwise, all photographs were taken by A. Gittenberger. The shell height was measured as the length of a line ( fig. 1: sh), running parallel to the columella, from the top of the protoconch to the most basal point of the aperture; the apertural height is the distance ( fig. 1: ah) between the uppermost and the most basal point of the aperture. The shell width was measured perpendicular to the columella, as the distance (fig. 1: sw) between the left and the right side at the periphery of the shell; the width of teleoconch whorl T3 (figs 1-2: T3, T3w) is the distance between the left and the right side of teleoconch whorl 2¾-3¼. It can only be measured when the protoconch-teleoconch border (PT) is centred, as is illustrated in figure 2. This character was routinely measured in Epitonium ulu Pilsbry, 1921, and conchological siblings, where it turned out to be discriminating to some extent. The 'shell height / shell width' (= H/W) and 'apertural height / shell height' (= A/H) values were only calculated for shells that are higher than 5 mm, to allow for better comparisons. Specimens shorter than 5 mm were also studied, especially for the umbilical region.
In most cases the protoconch and the teleoconch whorls could easily be distinguished. The border between protoconch 1 (developed within an eggcapsule) and protoconch 2 (developed after hatching, before the settling stage) is not visible in epitoniid species. Protoconch 1 and 2 are therefore not described separately. In some species almost all protoconchs are badly damaged or broken away and no sculpture can be described for them. Usually the embryonic whorls remain relatively intact, however, still showing the characteristic sculpture of axial always be sharply diagnosed conchologically. The existence of several of these species became especially obvious while trying to characterize the wentletrap species that are associated with corals with molecular markers in an attempt to reconstruct their phylogeny. The data obtained by DNA sequencing (A. Gittenberger et al., in prep.) clearly indicate that there are a much larger number of separate gene pools than previously thought. Some of these species are widespread and several of them may occur sympatrically, though with different coral hosts. Single specimens could not always be identified without molecular data. However, when the identity of the coral host species was known for sure, with the locality where it was found, the identity of the associated epitoniid, determined also by DNA sequencing, could be predicted correctly in all cases. This is the third contribution in a series of papers aiming at a better knowledge of the epitoniid species (Gastropoda: Epitoniidae) associated with corals (Scleractinia). For a more general introduction to the systematics, morphology and ecology of the large 'convenience genus' Epitonium, which ought to be split into smaller units, see also A. Gittenberger et al. (2000) and A. Gittenberger (2003).
An epitoniid tooth is attached to the radular plate along its bases (figs 13-15: ba). The part of the tooth lines. The initial teleoconch whorls are referred to as whorls 1-3. A quantitative description of the shell sculpture is given for the 2 nd and the 5 th teleoconch whorl and, whenever relevant, also for the 3 rd .
When there are over 20 spiral threads on a whorl, they are referred to as 'numerous'.
Although an epitoniid operculum can have a microsculpture on both its inside (figs 4-5) and outside (figs 3, 132-151), not enough material was available to study both sides for all species. We concentrated on the outside, because it has turned out to be speciesspecific for at least some epitoniids (Bonfitto and Sabelli, 2001;A. Gittenberger, 2003). On all SEM photographs (figs 132-151) the growth lines, which are clearly seen in e.g. figure 132, run from the lower left to the upper right corner ( fig. 3). The sculpture, which can be more or less obsolete, is the same all over the outside of the operculum.
Jaws and radulae were studied for most species. They were prepared from specimens with a shell height exceeding 5 mm.
Epitoniids have a ptenoglossan radula without a rachidian (Graham, 1965;Boss, 1982;Bandel, 1984;Page and Willan, 1988). No distinction can be made between marginal and lateral teeth. On an epitoniid radula the teeth may differ in size and number of secondary cusps. Half a row of teeth is described from the centre to the margin, by the number of teeth with a specific number of secondary cusps (table 2) and the sizes of the innermost, the largest, the penultimate and the ultimate (outermost) teeth (table 2). Additionally the position of the largest tooth is noted and a description is given of the morphology of the stem and the blade of a tooth (figs 13-15).
Because most of the epitoniids were conserved in alcohol 96%, the tissue of these specimens was hardened which hampered dissection and further anatomical analyses.
The egg-capsules were photographed and measured submerged in ethanol. Although the ethanol may extract water, no clear difference in egg-capsule height and width was found when comparing photographs in ethanol and in situ.
The mucus threads that connect the egg-capsules are indicated as either straight or twisted. While scoring this character, a single mucus-thread, about 0.5 mm long, in between two egg-capsules, should be studied at about 500×. In general, in a mucus thread that is considered to be 'straight', up to two twists per 0.5 mm may still be present. In contrast, in a 'twisted' mucus-thread, at least five, and usually many more, twists are present. Often two straight mucus threads were found twisted around each other, giving the appearance that they are twisted themselves. Apart from this, pulling on a twisted mucus thread may strongly reduce the number of twists.
In Makassar, SW Sulawesi, Indonesia and Koror, Palau, egg-capsules of the species Epidendrium aureum spec. nov., Epifungium adgravis spec. nov., E. hartogi, E. hoeksemai, E. lochi, E. nielsi spec. nov., E. twilae (A. Gittenberger and Goud, 2000), E. ulu, Surrepifungium costulatum, S. ingridae and S. patamakanthini spec. nov. were kept in an aquarium. Each day, some capsules were cut open in a drop of seawater on a glass-slide, in such a way that the embryos and/or veligers were alive during observations. The developmental stages were studied then through a microscope and photographed with a digital camera or filmed with a video camera. Part of the results of this experiment was already published in the species description of E. hartogi (A. Gittenberger, 2003: 147, fig. 42). The development of the other species will here be compared with that of E. hartogi as described by A. Gittenberger (2003). The results will be described in more detail in a note about the development of epitoniid veligers in general (A. Gittenberger and Reijnen, in prep.).
Each examined sample from the Leiden Museum is cited as RMNH, followed by the institutional registration number. After a slash the material in question is specified in more detail, using the abbreviations sh (number of empty shells), sn (preserved snails), +e (with egg-capsules), r (preserved radula), and d (with DNA-extract). For example "RMNH 95082/2sh, 3sn+e, r, 2d" refers to a sample with RNMH registration no. 95082, containing two empty shells, 3 snails with egg-capsules preserved in ethanol, one preserved radula and two DNA-extracts (of two snails). In the section Material, the type locality is listed first, followed by the countries and localities sorted by geological position, from West to East and from North to South. Because the material came from a variety of sources, not all the locality descriptions are equally detailed.
Unless stated otherwise, all specimens cited for the new species have to be considered paratypes.
In general, the full (sub)genus name is used only for the first species name in a paragraph; in all following names with the same (sub)genus, it is abbreviated. When two genera with the same first letter are mentioned in one paragraph, the full name may be repeated to avoid confusion. The first time a snail species is mentioned and in the header of its description, the author(s) are added; most of these species are first mentioned in this materials and methods section. The author(s) of the coral species are only added in the "habitat" paragraphs.
Character states that are shared by all species of a genus, i.e. several "soft parts" and "spawn" characters, are only mentioned in the genus description.

Systematics
Epitoniidae Berry, 1910 In general, shells of epitoniids that are associated with corals are fragile, i.e. most of the protoconchs, the apertures, and the costal ribs are badly damaged already in life. Shells in other epitoniid species are usually more strongly built.
Operculum. Nine to twenty wavy threads per 0.1 mm, running about perpendicular to the growth lines over the outside of the operculum (figs 136-139; Bonfitto and Sabelli, 2001: 271, fig. 2B). The threads are segmented by line fragments, which are convex towards the operculum edge.
Radula (table 2). All single teeth have a distinct basal denticle, an acute apical cusp and occasionally an inconspicuous, secondary cusp (figs 184-188, 204-208). The teeth in a row differ distinctly only in size.
Habitat. The snails live at the surface of the sand or buried within it, underneath fungiid corals (Fungiidae). They were never found on the corals themselves. In contrast, snails belonging to Epifungium gen. nov. were seen nearby, but crawling on the coral surface.
Etymology. Surrepifungium is composed after "surrepi", Latin for "to creep or crawl up from below", and "fungium", referring to the coral host family "Fungiidae". The name can also be read as "surr", a wrong inflection of "sub", standing for "below" and "epifungium", after Epifungium gen. nov. The gender is neuter, i.e. with the ending "ium".  . 135), no operculum sculpture is present, except for the growth lines. The operculum sculpture of other epitoniids is unknown.
The structure of the jaws appears to be most clearly diagnostic for the genus. In Epitonium ancillottoi and E. spec. 1 (figs 30, 219-222), which both resemble Surrepifungium ingridae conchologically, and in epitoniids of Epifungium gen. nov. (figs 243-263), which are associated with the same coral host species as the Surrepifungium gen. nov. species, there is only a single row of blunt denticles on the jaw-edge instead of several rows of acute ones. In Cirsotrema varicosa and Gyroscala lamellosa (figs 215-217), which differ clearly by their strong shells with a rough surface, there are multiple rows of denticles. These two species closely resemble each other in jaw structure, differing from the Surrepifungium gen. nov. species by relatively blunt denticles, no jaw-flap and a distinct, outside jaw-pattern with arch-like, raised and sunken figures (figs 17-19, 215-216).
The habitat is partly shared with several Epifungium gen. nov. species, which occasionally occur on the bottom underneath fungiids. When they were found together (n = 24), the snails of Epifungium gen. nov. were on the coral and those of Surrepifungium gen. nov. on or in the sand underneath. This is more likely due to a dislike of sand by the snails of Epifungium gen. nov., than due to interspecific competition (A. Gittenberger and Hoeksema, in prep.). The habitat seems not to be shared with any other epitoniids.
Radula (figs 163-164, 184-185, 204-205; table 2). Two radular types were found in Surrepifungium costulatum. One in a specimen from Indonesia, (type 1) and the other one in a specimen from Palau (type 2). These two snails were found underneath the same coral species, i.e. Ctenactis echinata (Pallas, 1766), and their shells are indistinguishable. In both types the stem and the blade of each tooth are similar in width and merge gradually.
In type 1 ( fig. 163), the innermost tooth ( fig. 185, left) and the penultimate one ( fig. 205) both have an inconspicuous, blunt, secondary cusp, which is absent in all other teeth. Starting from the innermost, smallest tooth, with a height of 0.065 mm, the teeth gradually increase in size to twice that height, i.e. 0.130 mm, up to the 7 th tooth, after which they gradually become smaller again until the ultimate, i.e. 23 rd tooth, which is 0.082 mm high (table 2). All teeth are attached to the radular plate along the bases up to the basal denticle.
In type 2 ( fig. 164), the innermost tooth ( fig. 184, left) has an inconspicuous, blunt, secondary cusp, which is absent in all other teeth. Starting from the innermost, smallest tooth, with a height of 0.030 mm, the teeth gradually become elongated and very slender, increasing in size to almost seven times that height, i.e. 0.195 mm, up to the penultimate tooth ( fig. 204). After that the smaller, usually malformed, 0.120 mm high 21 st tooth follows (table 2). In some of the largest teeth, the bases of the stem become partly detached from the radular plate, just below the basal denticle. Jaw (figs 226-227; table 2). The jaws associated with both the radular types are similar. The denticulate edge consists of three or four irregular rows of basally pitted, slender, acute denticles, best visible from the inside of the jaw ( fig. 227). The denticles in the   Gittenberger, upper row are usually the largest ones, i.e. 0.020-0.030 mm (n = 2) in height. Seen from the outside ( fig. 226), 14-14 denticles per 0.05 mm (n = 2) extend above a 0.019-0.020 mm (n = 2) broad, relatively smooth to slightly granulated jaw-flap, which merges with the jaw along a zone with a distinct pattern of deeply sunken, pitted, irregular to pentagonal figures. Underneath the jaw-flap, a pattern of irregular to pentagonal figures quickly becomes obsolete. On the inner surface ( fig. 227) no pattern is present. . The irregularly pentagonal, drop-shaped egg-capsules are covered with sand. They are 5.0-6.1 mm (mean = 5.3, n = 20) in diameter, e.g. measured horizontally, from left to right in figure 264, and contain 70-345 eggs (mean = 180, n = 10). A straight mucus thread ( fig. 265), finely sculptured with longitudinal lines, connects the eggcapsules along their bases (on the left in fig. 264).
Differentiation. Shells of this species most closely resemble those of Surrepifungium oliverioi (Bonfitto and Sabelli, 2001) and S. patamakanthini spec. nov. See the differentiation of those species for details.
Remarks. For a photograph of the holotype, a more detailed description of the shell and the proboscis, and a comparison with Epitonium pallasii (Kiener, 1838), see A. Gittenberger et al. (2000). Here some additional data are given, with notes that may be relevant for the differentiation of this species. See also the remarks on S. oliverioi.
Remarks. For a more detailed description of the shell and the proboscis, see A. Gittenberger et al. (2000). Here some additional data are given, with notes that may be relevant for the differentiation of this species.
Surrepifungium oliverioi (Bonfitto and Sabelli, 2001) Epitonium oliverioi Bonfitto and Sabelli, 2001 with the jaw along a zone with a distinct pattern of deeply sunken, pitted, pentagonal figures. Underneath this zone, no distinct pattern is present. On the inner surface ( fig. 235) no pattern is present. . The irregularly pentagonal, drop-shaped egg-capsules are covered with sand. They are 2.5-3.5 mm (mean = 3.2, n = 10) in diameter, e.g. measured horizontally, from left to right in figure 270, and contain 135-160 eggs (mean =149, n = 10). A straight mucus thread ( fig. 271), finely sculptured with longitudinal lines, connects the eggcapsules along their bases (on the left in fig. 270).
Habitat. The snails and their egg-capsules were found at 4-38 m depth, associated with Fungia (Fungia) fungites (Linnaeus, 1758), F. cf (Verrillofungia) repanda Dana, 1846, Herpolitha limax (Esper, 1797) and Sandalolitha robusta (Quelch, 1886). These mushroom coral species occur both on sand and on a more solid substratum, but the snails with the egg-capsules were found on or in the sand (sometimes buried) only.
Distribution ( fig. 45). The species is known from the Indo-West Pacific, from Egypt (Red Sea), Madagascar, Maldives and Indonesia to Palau.
Differentiation. Conchologically this species most closely resembles Surrepifungium costulatum (figs 34-35). The radula of S. oliverioi is similar to the "type 2" radula of S. costulatum (see the description of that species; figs 164, 184, 204). Furthermore the DNA-sequences (Cytochrome Oxidase I) found for eight S. costulatum and four S. oliverioi specimens are very similar and therefore not diagnostic (A. Gittenberger et al., in prep.). In general, the species can be distinguished by their shells, which are usually somewhat more loosely coiled in S. oliverioi (figs 36-37) than in S. costulatum (figs 34-35) and by their egg-capsule sizes, which are 2.5-3.5 mm in S. oliverioi versus 5.0-6.1 mm in S. costulatum. These differences may also represent intraspecific variation, suggesting that S. oliverioi and S. costulatum are conspecific. Surrepifungium costulatum however, is the only species that was found to have two types of radula. This may indicate the presence of an additional, cryptic species instead of a dimorphism within the species. If so, a name may be available already. Because of this uncertainty, Surrepifungium costulatum and S. oliverioi are here still considered separate species. Future analyses of additional molecular markers and the jaws of a larger number of specimens, can resolve this issue. Shells of S. oliverioi also resemble those of S. patamakanthini spec. nov., but differ in having solely "single" Remarks. The description given above has to differ from that by Bonfitto and Sabelli (2001), because some paratypes were found to be not conspecific with the holotype. Three paratypes were studied. Their heights are 17.0, 15.8 and 9.1 mm ( fig. 33). They correspond with paratypes 1 (MZB 14026), 2 (MZB 14027) and 4 (BMNH ?) in Bonfitto and Sabelli (2001 96) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 23 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch (figs 38-39, 50, 114) has up to 11½ whorls, separated by a very deep suture; it is sculptured with mostly regularly placed, orthocline, lamellar, moderately high costae, which are usually continuous on the initial teleoconch whorls only. Costae touching the adjoining whorls and usually curving adaperturally at the preceding whorl. Shortly before the preceding whorl is reached, the costae increase abruptly in height, forming a distinct coronation ( fig. 114). Initial whorls usually with multiple, lamellate costae, which are fused to form broader ones (figs 96, 114). The number of costae on the initial five teleoconch whorls remains approximately the same, i.e. about 16 ribs per whorl (table  1); it only increases on the younger whorls, with 21-25 (mean = 22.6, n = 15) costal ribs on the 8 th -10 th teleoconch whorl in shells with a height of 16-19 mm, and even up to 46 costae on the 10 th whorl in a shell of 21.0 mm in height. The teleoconch is additionally sculptured with very low, inconspicuous, randomly placed, spiral threads (figs 96, 114), which become obsolete from about the 6 th teleoconch whorl onwards. Aperture subcircular. There is a narrow but distinct umbilicus.
Operculum ( has an inconspicuous, pointed, secondary cusp, which is absent in all other teeth. Starting from the innermost, smallest tooth, with a height of 0.030-0.037 mm (mean = 0.033, n = 3), the teeth quickly increase in size to about four times that height up to the 3 rd tooth, after which they gradually become somewhat larger still, up to the largest, 0.150-0.171 mm (mean = 0.159, n = 3) high tooth, which is either the penultimate or the ultimate one, i.e. the 12 th . In two radulae, the ultimate tooth was c. 0.050 mm smaller, i.e. 0.102-0.126 mm high, than the 0.150-0.171 mm high penultimate one. In the third radula the ultimate tooth was slightly larger, i.e. 0.155 mm, than the penultimate one, i.e. 0.153 mm (table 2). Jaw (figs 6-7, 231-233; table 2). The denticulate edge consists of three to five irregular rows of basally pitted, slender, acute denticles, best visible from the inside (figs 232-233). The denticles in the upper row are usually the largest ones, i.e. 0.020-0.022 mm (mean = 0.021, n = 3) in height. At the outside ( fig.  231), 16-18 denticles per 0.05 mm (mean = 17, n = 3) extend above a 0.020 mm (n = 1) broad, densely pitted jaw-flap, which merges with the jaw along a zone with a pattern of slightly raised, scarcely pitted, irregular to pentagonal figures Differentiation. Conchologically and in habitat preference, this species resembles Surrepifungium costulatum, S. oliverioi and S. ingridae. It differs from these three species in having 12 instead of more than 17 radular teeth in half a row (table 2). It can furthermore be distinguished from S. costulatum and S. oliverioi by the presence of fused lamellae forming thick costal ribs on the initial whorls and the coronations on the ribs. It differs from S. ingridae in having 13-20 (mean = 16.1, n = 23) costae instead of 20-31 (mean = 24, n = 5) costae on the 5 th teleoconch whorl (see table 1) and by the lack of a distinct spiral sculpture from about the 6 th teleoconch whorl onwards.
Etymology. This species is named in appreciation of Mr Somnuk Patamakanthin, for his hospitality at the Phuket Shell Museum and the donation of specimens of Surrepifungium costulatum and S. patamakanthini from Thailand.
New species. Pending additional data, the following two species are provisionally classified in Epitonium, calling attention to these forms by describing, illustrating and naming them. Operculum, Radula, Jaw and Spawn. Unknown.
Habitat. One empty shell was found on sand beneath the mushroom coral Fungia (Cycloseris) costulata Ortmann, 1889, at a depth of 9 m.
Differentiation. This species differs from all other epitoniids in the position of the coronations on the costae, just above the periphery of the whorls. A similar sculpture of an increasing number of fused lamellate costae, forming thick costal ribs up to at least the 6 th teleoconch whorl, has also been found in some specimens of Surrepifungium ingridae ( fig.   113; A. Gittenberger et al., 2000: 8, figs 23-24, 27) and S. patamakanthini spec. nov. (fig. 114).
Remarks. The shell height could not be measured accurately because of the missing protoconch whorls. Therefore the indexes based on this height, cannot be accurate either. This species could also be classified with Surrepifungium gen. nov., because of the fused, lamellate, thick costal ribs and its association with a fungiid coral. Etymology. Graviarmatum is composed after "gravi", Latin for "heavily", and "armatum", Latin for "defensively armed".
Remarks. This species might in fact belong to Surrepifungium gen. nov., because of the lack of a spiral sculpture on the teleoconch and its association with a fungiid coral.
Shell (table 1). The fragile shells have a distinct teleoconch sculpture of low, costal ribs and spiral threads. Among the four Epidendrium gen. nov. species the shell shapes vary between very broad and relatively slender conical (figs 1, 51-57; table 1; Bouchet and Warén, 1986: 522, figs 1217, 1218. Both slender and broad shells were found in samples collected from the same host. Both forms were found laying egg-capsules, so that the variation cannot be explained by differences in sex.
Operculum. Except for growth lines, no micro-sculpture is present on the outside of the opercula of Epidendrium aureum spec. nov. and E. sordidum spec. nov. The opercula of E. billeeanum and E. dendrophylliae could not be studied.
Soft parts. The animal is yellowish, with small, dark eyespots.
The habitat seems not to be shared with any other epitoniid species.
Remarks. Because specimens of the two Indo-West Pacific species Epidendrium aureum spec. nov. and E. sordidum spec. nov. were repeatedly confused with the East Pacific Epitonium billeeanum Dushane and Bratcher, 1965, the data presented on allegedly that species by several authors (Debelius, 1996a;Debelius, 1996b;A. Gittenberger, 2003;Loch, 1982;Oliverio et al., 1997;Robertson and Schutt, 1984;Page and Willan, 1988) should be treated with care. Page and Willan (1988) concluded that snails of E. billeeanum from the Great Barrier Reef, Australia, change sex between 8.6 and 12.7 mm shell length, and that their radulae go through an ontogenetic change while doing so. The two radula-types that are described for males and females of E. billeeanum, are similar to those of E. sordidum spec. nov. and E. aureum spec. nov., respectively. Probably Page and Willan (1988) have misidentified their specimens as E. billeeanum, a species that, according to our data, only occurs in the East Pacific. Shells of E. sordidum spec. nov. and E. aureum spec. nov. often occur sympatrically, in large numbers, on the same host colony. In general the shells of E. sordidum spec. nov. are smaller than those of E. aureum spec. nov., explaining the association Page and Willan (1988) found between shell size and radular type. See also the remarks on E. aureum spec. nov.

Epidendrium aureum spec. nov.
Scalina billeeana Bratcher, 1965: Oliverio et al., 1997: 3-10, figs 1-21; Robertson and Schutt, 1984 . 92) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 21-22 (mean = 21.7, n = 3) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch (figs 51-52, 118) has up to 8¾ whorls, separated by a moderately deep suture; it is sculptured with mostly regularly placed, discontinuous, orthocline, lamellar, not or slightly curved, low costae, not or hardly touching the adjoining whorls. The number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls usually increases quickly, up to 164 costae on the 7 th whorl in a shell of 12.0 mm in height. The teleoconch is additionally sculptured with regularly placed, relatively thick, spiral threads. The number of prominent spirals on the 2 nd , 3 rd , 5 th teleoconch whorls slowly increases, usually remaining approximately the same from the 6 th whorl onwards; there are up to 35 spirals on a whorl. The lamellar costae increase slightly in height when running over the spiral threads. Aperture subcircular. There is a moderately wide umbilicus.  . 238). They have a maximum size of 0.0048-0.0070 mm (n = 2). Seen from the outside (figs 22, 236-237), 38-46 denticles (n = 2) per 0.05 mm extend above a 0.026-0.026 mm (n = 2) broad, granulated jaw-flap ( fig. 22), which lies loosely over part of the jaw-pattern (figs 29, 236-237). This pattern, as far as visible under the jaw-flap, consists of two or three rows of somewhat sunken, densely pitted, pentagonal figures, followed further on by one or two rows of deeply sunken, scarcely pitted, pentagonal figures, and after that by more or less unclear rows of somewhat sunken, scarcely pitted, pentagonal to irregular figures that occasionally have holes ( fig. 237; as in Epidendrium sordidum spec. nov., fig.  20). Away from the denticulate edge, the pattern gradually becomes obsolete ( fig. 236). On the inner surface of the jaw ( fig. 238), below the denticles, there are three to five rows of engraved, scarcely pitted, square-like figures, followed by an area that is somewhat granulated to smooth.  fig. 1). The species was observed, but not collected, by the first author in Japan, Okinawa, off Akajima island, and in NE Australia, off the 3 rd ribbon reef and off Osprey reef.
Differentiation. The shells of this species most closely resemble those of Epidendrium billeeanum Dushane and Bratcher, 1965. They differ in having a dark purplish red instead of a white to yellowish protoconch. Another difference concerns the radula. In E. aureum spec. nov. there is no distinct secondary cusp on the elongated, slender radular teeth, as was figured for E. billeeanum by Dushane and Bratcher (1965: pl. 24, fig. 3a). The largest teeth are the 12 th -22 th in half a row of 30-34 teeth in E. aureum spec. nov. (table 2), while according to Dushane and Bratcher (1965: 161), the outermost radular teeth are the largest in E. billeeanum. Shells of E. aureum spec. nov. also resemble those of E. sordidum spec. nov.; they can easily be distinguished, however by the teleoconch sculpture of ribs that do not distinctly vary in height, instead of ribs that abruptly become two to three times higher, forming distinct protuberances, where running over the spiral threads.
Etymology. This species is named after its in situ brightly yellow colour, which gives it a golden hue.
Remarks. The morphological differences between shells of Epidendrium billeeanum from the type locality in Baja California, and the epitoniid species here described as E. aureum spec. nov. and E. sordidum spec. nov. from the Indo-West Pacific, were regarded as intraspecific variation in the literature, mainly because of the absence of sufficient material for study (e.g. Oliverio et al., 1997;Loch, 1982). With hundreds of specimens from the Red Sea, Maldives, Thailand, Philippines, Indonesia and Palau available, it became obvious that these shells from the Indo-West Pacific are consistently different from the 10 shells that were studied from Baja California. Thus, the commonly used vernacular name "Golden Wentletrap" refers to three species, i.e. E. aureum spec. nov., E. billeeanum and E. sordidum spec. nov. These findings and the data obtained by a DNA-analysis (A. Gittenberger et al., in prep.) convincingly show that the Indo-West Pacific specimens represent two species that are both new to science, viz. E. aureum spec. nov. and E. sordidum spec. nov. Although E. sordidum spec. nov. is only slightly less common than E. aureum spec. nov. and occurs sympatrically with it at most localities, recognizable photographs of golden wentletraps from the Indo-West Pacific, always show E. aureum spec. nov. This is probably because in E. aureum spec. nov. the shells are usually somewhat larger and not as dirty as in E. sordidum spec. nov. Golden wentletraps on photographs from the Galapagos islands (various internet sources), do not show pigmented protoconchs. Therefore, they are considered conspecific with E. billeeanum ( fig. 56), which was also cited from the Galapagos islands by Dushane and Bratcher (1965: 161).
Radula (table 2). Dushane and Bratcher (1965: pl. 24, fig. 3a-b) figured the c. 0.076 mm high, slender, elongated teeth of the holotype, which have either a single, acute or no secondary cusps (where these teeth are situated in a row is not indicated). According to Dushane and Bratcher (1965) the holotype has an indefinite number of these teeth, the outermost of which are the largest. Similar slender, elongated teeth without secondary cusps are known from Epidendrium aureum spec. nov. (fig. 203) fig. 284). The yellow "eggs" that are described by Dushane and Bratcher (1965: 161) are probably egg-capsules.
Distribution. The species is known from the Gulf of California and the Galapagos archipelago.
Differentiation. See the differentiation of Epidendrium aureum spec. nov.
Remarks. For a more detailed description, see Dushane and Bratcher (1965). Here some additional data are given, with notes that may be relevant for the differentiation of this species. See also the remarks on Epidendrium aureum spec. nov.
Radula. The radular teeth as described and figured by Richter and Luque (2004: 99-100, fig. 1c-d) have two to six acute, secondary cusps. The apical cusp is about 1½ to 2 times larger than the secondary cusp(s) underneath it. The secondary cusps resemble each other in size.
Jaw. The denticulate jaws have a reticulate pattern on the surface (Richter and Luque, 2004: 99).
Habitat. The snails are found on dendrophylliid corals. Although they usually occur deeper than 40 m and in association with the coral genera Dendrophyllia and Balanophyllia, Richter and Luque (2004) recorded one specimen from 19 m on Astroides calycularis (Pallas, 1766).
Distribution. The species is known from the eastern Atlantic and the western Mediterranean (Richter and Luque, 2004).
Remarks. For a detailed description and a comparison with Epitonium striatissimum (Monterosato, 1878) see Bouchet and Warén (1986) and Richter and Luque (2004). Here some additional data are given, with notes that may be relevant for the differentiation of this species. See also the remarks on Epidendrium aureum spec. nov.  . 93) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 20-25 (n = 2) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch (figs 1-2, 53-55, 119) has up to 7 whorls, separated by a moderately deep suture; it is sculptured with mostly regularly placed, discontinuous, orthocline, lamellar, not or slightly curved, low costae, not or hardly touching the adjoining whorls. The number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls increases quickly, up to 80 costae on the 6 th whorl in a shell of 7.0 mm in height. The teleoconch is additionally sculptured with regularly placed, relatively thick, spiral threads. The number of prominent spiral threads on the 2 nd , 3 rd , and 5 th teleoconch whorl slowly increases at first, usually remaining approximately constant from the 6 th whorl onwards; there are up to 10 spirals on a whorl. The low costal ribs increase abruptly two to three times in height when crossing a spiral thread, forming distinct protuberances on the shell's surface. Mucus threads, dirt and sand are caught in between these protuberances; small bivalves, vermetid gastropods, polychaetes and foraminifers, often settle on them (figs 1-2); small circular holes of unknown origin, are commonly found in between the costae (see teleoconch whorls 4-5 of the holotype, fig. 53). Therefore, when collecting the snails in the field, they are usually so dirty that the whorls cannot be distinguished. Cleaning takes some effort and normally results in shells that still look worn and dirty (figs 53-54), and only rarely "clean" (fig. 55). Aperture subcircular. There is a moderately wide umbilicus.
Operculum ( fig. 134). Operculum paucispiral, with interconnected coils as in Surrepifungium patamakanthini spec. nov. (fig. 3). Except for growth lines, no micro-sculpture ( fig. 134) . 202). The number of secondary cusps gradually increases from 1 on the innermost tooth ( fig. 182, left) to 9 on the teeth about halfway, after which the number gradually decreases to 2 on the ultimate tooth. The apical cusp is about two to three times larger than the secondary cusp underneath it. Secondary cusps gradually become smaller further down the blade of a tooth ( fig. 202). Only the radula of the holotype (figs 162, 183, 203) could be preparated good enough to accurately measure and count all teeth. It looks similar to the other two radulae that were studied. Starting from the innermost, smallest tooth, with a height of 0.041-0.044 mm (n = 2), the teeth gradually increase in size to somewhat more than twice that height, i.e. 0.108 mm (n = 1), up to the 46 th tooth, after which they gradually become smaller again until the ultimate, 0.074 mm (n = 1) high 59 th tooth (table 2).
Jaw (figs 20, 239-242; table 2). The denticulate edge consists of a row of slender, blunt denticles, which are densely pitted basally, on the inside ( 240), followed further on by more or less unclear rows of somewhat sunken, scarcely pitted, pentagonal or oval to irregular figures that occasionally have holes (figs 20, 242). Away from the denticulate edge, the pattern gradually becomes obsolete ( fig. 241). On the inner surface of the jaw ( fig. 239), below the denticles, there are three or four rows of engraved, scarcely pitted, irregularly square-like figures, followed by an area that is somewhat granulated to smooth.
Habitat. The snails and their egg-capsules were found at 3-35 m, associated with Tubastrea and Dendrophyllia corals. They usually live on, or in the vicinity of their dendrophylliid hosts, attached to the surface of the substrate with mucus threads. The host corals occur most commonly fixed to the underside of large boulders, in crevices, on the ceilings of caves or on the steep walls of drop-offs. The snails are often found together with those of Epidendrium aureum spec. nov. with the same coral host colony.
Distribution ( fig. 59). The species is known from the Indo-West Pacific, from Maldives, Philippines and Indonesia to Palau.
Differentiation. See the differentiation of Epidendrium aureum spec. nov.
Etymology. This species is named after its appearance. Most shells, even of alive specimens, look worn and "dirty", i.e. "sordidum" in Latin. Operculum. Twenty to forty wavy threads per 0.1 mm, running about perpendicular to the growth lines over the outside of the operculum (figs 140-151).
Soft parts. The animal is whitish, with small, dark eyespots.
Spawn. The egg-capsules are oval to round, with or without protuberances, transparent or covered with sand. They are connected by a straight or twisted mucus thread (figs 276-299). The uncleaved eggs are 0.077 mm (n = 10 / species) in diameter. The development from eggs to veligers in the egg-capsules resembles that described for E. hartogi by A. Gittenberger (2003: 147, fig. 42). This development was studied for all Epifungium gen. nov. species, except E. adscabra spec. nov., E. marki spec. nov., E. pseudolochi spec. nov. and E. pseudotwilae spec. nov.
Habitat. The snails live under fungiid hosts (Fungiidae) on the coral itself or on the substratum under-neath, with the exception of Epifungium hartogi, which is found on or in the vicinity of euphyllid hosts (Euphyllidae). When the snails are not on the coral surface, they are usually found on a hard substratum, like coral rubble and only rarely on sand.
Etymology. The name Epifungium is composed after "epi", Greek for "on", and "fungium", referring to the coral host family "Fungiidae". The gender is neuter, i.e. with the ending "ium".  . 134) and Epitonium pyramidalis ( fig. 135), no operculum sculpture is present, except for the growth lines. The sculpture on the opercula of other epitoniids, if any, is unknown.
Similar, round to oval egg-capsules are found in species of most epitoniid genera, with the exception of Surrepifungium gen. nov., in which only pentagonal, drop-shaped egg-capsules are present.
The habitat is partly shared with Surrepifungium gen. nov. species, which live in or on the sand underneath fungiid host corals. When they were found together (n = 24), the snails of the Epifungium gen. nov. species were on the coral and Surrepifungium gen. nov.   Fig. 68, E. pseudolochi spec. nov., holotype, Egypt. Fig. 69, E. adscabra spec. nov., holotype, Sulawesi, Indonesia. Scale bar = 1 cm. was found on or in the sand underneath. This is most likely due to a dislike of sand in Epifungium gen. nov. species, and not a matter of interspecific competition (A. Gittenberger and Hoeksema, in prep.). The habitat seems not to be shared with any other epitoniids.
Epifungium adgranulosa spec. nov. Material . 100) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 19 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch ( fig. 120) has up to 10 whorls, separated by a shallow suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, low costae, touching the adjoining whorls, curving adaperturally at the preceding whorl. Just before reaching the preceding whorl the costae usually become about four times higher, forming a coronation. Although the number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls remains approximately the same (adjoining whorls differing +/-2) in about half of the specimens, this number may strongly increase or decrease on two or three whorls after which it remains constant again. There are up to 37 costae on a whorl, as was counted on the 9 th whorl in a shell of 8.5 mm in height. The teleoconch is additionally sculptured with very low, inconspicuous, spiral threads, randomly placed over each whorl. On the initial whorls the spiral threads are usually obsolete. Towards the younger whorls additional, low, spiral threads become apparent, usually (27 out of 31) becoming numerous from about the 7 th teleoconch whorl onwards. In some rare cases, 16 spiral threads are present on the 7 th teleoconch whorl (2 out of 33) or the spiral sculpture becomes obsolete on the younger whorls (2 out of 33). Aperture subcircular. Most specimens (30 out of 36) have a very narrow umbilicus, visible in oblique view only. Six specimens have a closed umbilicus. The relative umbilical width is not correlated with the shell-size.
Radula and Jaw. Unknown. . Egg-capsules ( fig. 276) ovoid, with conspicuous protuberances, somewhat transparent when not embedded with sand, 1.00-1.69 mm (mean = 1.24, n = 15) in diameter, e.g. measured horizontally, from left to right in figure 276, containing 120-445 eggs (mean 183.2, n = 15) each. The mucus threads that connect the egg-capsules are strongly twisted and not sculptured ( fig. 277). Habitat. The snails and their egg-capsules were found at 3-18 m, associated with exclusively the mushroom coral species Fungia (Wellsofungia) granulosa Kluzinger, 1879. The snails usually live attached with their mucus threads to the underside of their hosts or to hard substrata underneath. Most host corals were found on coral slopes. Distribution ( fig. 60). The species is known from the Indo-West Pacific, from Egypt (Red Sea), Maldives and Thailand to Indonesia. Also off Palau, many specimens of the host coral species F. (W.) granulosa were thoroughly inspected for wentletraps but no Epifungium gen. nov. species were found there.
Differentiation. Conchologically this species resembles Epifungium adgravis spec. nov., E. marki spec. nov. and E. nielsi spec. nov. most. It differs from these species most clearly by its only slightly convex, instead of distinctly convex whorls and by the costal ribs touching the preceding whorls while curving adaperturally. Epifungium adgranulosa spec. nov. is the only epitoniid species that is known to be associated with Fungia (Wellsofungia) granulosa.
Etymology. This species is named after its restricted habitat. It was found exclusively on corals of Fungia (Wellsofungia) granulosa.
The teleoconch ( fig. 121) has up to 10 whorls, separated by a deep suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, not to slightly curved, low costae, not Figs 77-78. Epifungium marki spec. nov. and its host coral Fungia (Pleuractis) spec. A, off Marsa Shagra (Red Sea), Egypt. 77, E. marki, holotype (largest specimen, shell height = 19.2 mm) with egg-capsules in situ; 78, F. (P.) spec. A, the two corals were collected on a sandy bottom and placed next to each other for better comparison; upper left specimen (coral length = 15 cm), host of E. marki holotype; lower right specimen, morph with many secondary mouths, host of several E. marki paratypes. or hardly touching the adjoining whorls. Just before reaching the preceding whorl the costae become slightly coronate. The number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls remains approximately the same (adjoining whorls differing in about two costae) in most cases; in a few specimens this number strongly increases or decreases on only two or three whorls. There are up to 31 costae on a whorl; on the 10 th whorl in a shell of 14.0 mm in height. Very fine, irregularly placed, incised, axial lines and/or split costae are present from the 7 th -9 th teleoconch whorl onwards. The teleoconch is additionally sculptured with irregularly placed, relatively thick, spiral threads. From the 6 th -9 th teleoconch whorl onwards, there are irregularly spaced, thin, spiral threads and incised spiral lines in between them and on the major spiral threads. There are usually less spiral threads above the periphery than below it; on the initial whorls they are usually obsolete above the periphery. The number of major spiral threads increases from the 2 nd to the 5 th whorl, after which it remains almost constant. From the 7 th -9 th whorl onwards, some of the incised spiral lines or low threads may gradually change into thick spiral threads. Aperture subcircular. In most specimens that are less than about 5 mm high (with 5-6 teleoconch whorls), the umbilicus is closed. Larger specimens have a very narrow umbilicus, visible in oblique view only.
Radula ( fig. 15; table 2). Two radulae from Indonesian snails could be studied. Both radulae curled and got damaged during SEM-preparation. Therefore it was hard to count the teeth in a row and as a consequence the numbers given below may not be accurate. Each tooth ( fig. 15) consists of a moderately broad stem and a somewhat broader blade, which merge gradually; the blade has 1-6 acute, secondary cusps.
The teeth ( fig. 15) are attached to the radular plate along the bases, which takes about half of the length of a tooth. The number of secondary cusps (table 2) gradually increases from 1 on the innermost tooth to 6 on the 10 th tooth ( fig. 15, indicated by "sc"), after which the number gradually decreases to 1 on the ultimate, i.e. 14 th tooth. The apical cusp and the secondary cusp directly underneath it are usually similar in size and somewhat curved towards each other; all other secondary cusps are slightly smaller, similar to each other in size, and usually not curved ( fig. 15). Starting from the innermost, smallest tooth, with a height of 0.020 mm (n = 1), the teeth gradually increase in size to about two times that height, i.e. 0.042 mm (n = 1), up to the 10 th tooth, after which they gradually become somewhat smaller until the penultimate, 0.036 mm high 13 th tooth, which is followed by the much smaller 14 th ultimate tooth, with a height of 0.022 mm (table 2). Jaw ( fig. 253; table 2). Only the outer surface of one jaw could be studied. The denticulate edge consists of a row of slender, blunt denticles ( fig. 253). They have a maximum size of 0.0033 mm. Seen from the outside ( fig. 253), 56 denticles per 0.05 mm extend above a 0.0100 mm broad, slightly granulated jawflap, which lies merged with the jaw over part of the jaw-pattern. This pattern, as far as visible under the jaw-flap, consists of two or three rows of somewhat sunken, densely pitted, pentagonal figures, under which the pattern is obsolete. . Egg-capsules ( fig. 278) ovoid, without any protuberances, sometimes embedded with sand, 0.69-1.58 mm (mean = 1.22, n = 15) in diameter, e.g. measured horizontally, from left to right in figure 278, containing 161-272 eggs (mean = 219.6, n = 13) each. The mucus threads that connect the egg-capsules are straight and not sculptured ( fig. 279).
Habitat. The snails and their egg-capsules were found at 6-30 m, associated with exclusively the mushroom coral species Fungia (Pleuractis) gravis Nemenzo, 1955. The snails usually live attached with their mucus threads to the underside of their hosts. Most host corals were found deeper than 20 meters, on a sandy, nearly flat bottom, situated along the lower border of a steeper coral slope.   83). It is the only epitoniid species that is known to be associated with Fungia (Pleuractis) gravis. Conchologically this species (figs 63-64, 101, 121) most closely resembles E. marki spec. nov. (figs 62, 77, 106, 126), which is endemic to the Red Sea ( fig. 83). Epifungium adgravis spec. nov. differs from E. marki spec. nov. in having 23-31 costae (mean = 25.8, n = 6) instead of 30-38 costae (mean = 33.3, n = 3) on the 9 th -10 th teleoconch whorl, 18 (n = 1) instead of 31 (n = 1) axial lines on protoconch whorl 2¼-2¾ (figs 101, 106) and in having 21-22 wavy, segmented threads per 0.1 mm (n = 2) on the operculum instead of 34 per 0.1 mm (n = 1) (figs 141, 146). In E. marki spec. nov. the shells also have a somewhat deeper suture (figs 62-64). The shells of E. adgravis spec. nov. also resemble those of E. nielsi spec. nov. (figs 65, 107, 127), differing especially by the more convex, somewhat broader whorls, which becomes apparent when the width of about the 3 rd teleoconch whorl is measured (table 1). Both major and minor spiral threads can be distinguished in most shells of E. adgravis spec. nov., but not in E. nielsi spec. nov. The spiral threads on the initial teleoconch whorls are usually obsolete above the periphery in E. adgravis spec. nov., where they are usually clearly discernible in E. nielsi spec. nov. The egg-capsules of E. adgravis spec. nov. and E. nielsi spec. nov. differ in being smooth ( Etymology. This species is named after its restricted habitat, being found exclusively on Fungia (Pleuractis) gravis Nemenzo, 1955. Remarks. Molecular analyses (A. Gittenberger et al., in prep.) indicate that Epifungium adgravis spec. nov. and E. adscabra spec. nov. (fig. 69) are sister species although they differ considerably conchologically. In shell characters E. adgravis spec. nov. is most similar to E. marki spec. nov., the sister species of E. pseudolochi spec. nov. These two species couples are sister groups again. See also the remarks on E. pseudolochi spec. nov.
Epifungium adscabra spec. nov. Material . 102) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 23 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch ( fig.  122) has up to 9¼ whorls, separated by a moderately deep suture; it is sculptured with mostly regularly placed, usually continuous, orthocline, lamellar, low costae, touching the adjoining whorls, slightly curving adaperturally at the preceding whorl. Costae usually not coronate; some costae become slightly coronate, just before reaching the preceding whorl. The number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls remains approximately the same (adjoining whorls differing in about two costae). There are up to 23 costae on a whorl; on the 6 th whorl in a shell of 6.8 mm in height. The teleoconch is additionally sculptured with very low, inconspicuous, spiral threads. On some teleoconch whorls the spiral threads are obsolete; on the initial whorls they are usually obsolete above the periphery. Although the number of spiral threads approximately doubles between the 2 nd and the 5 th teleoconch whorl, it usually remains the same afterwards. In some specimens the number of spiral threads keeps on increasing strongly, resulting in numerous spirals from about the 7 th whorl onwards. Aperture subcircular. Half of the specimens (7 out of 14) have a very narrow umbilicus, visible in oblique view only. The other seven specimens have a closed umbilicus. The size of the umbilicus is not correlated with shell-size.
Habitat. The snails and their egg-capsules were found at 3-18 m, associated with exclusively the mushroom coral species Fungia (Verrillofungia) scabra Döderlein, 1901. They usually live attached with their mucus threads to the underside of their hosts, close to the outer edge of the coral. Most host corals were found on coral slopes. Distribution ( fig. 79). The species has a relatively small range. It is only known from Indonesia.
Differentiation. The shells of this species resemble those of Epifungium adgravis spec. nov. and E. marki spec. nov., from which they can be distinguished by the much smaller width of the 5 th teleoconch whorl (figs 121-122, 126), the presence of on average 19-20 instead of 24-26 costal ribs on the 2 nd , 3 rd and 5 th teleoconch whorls (table 1), and an average shell height/width index of 2.0 instead of 2.9 (table 1). Epifungium adscabra is the only epitoniid species that is known to be associated with Fungia (Verrillofungia) scabra.
Etymology. This species is named after its restricted habitat. It was found exclusively on corals of Fungia (Verrillofungia) scabra.
Remarks. See the remarks of Epifungium adgravis spec. nov. and E. ulu.
Radula (figs 169, 189, 209; table 2). Three radulae from Indonesian snails could be studied (A. Gittenberger, 2000: 143). The teeth could be counted accurately in one radula only (table 2). Each tooth (figs 169, 189, 209) consists of a slender stem and broad blade, which merge gradually; the blade has 1-6 acute, secondary cusps. The teeth ( fig. 169) are attached to the radular plate along the bases, which takes about half of the length of a tooth. The number of secondary cusps (table 2) gradually increases from 1 or 2 on the innermost tooth ( fig. 189, left) to 6 on the penultimate, i.e. 24 th tooth ( fig. 209, right), after which the ultimate, i.e. 25 th tooth follows with 2 secondary cusps ( fig. 169, right). The apical cusp and the secondary cusp directly underneath it are usually similar in size and somewhat curved upward, away from the stem; all other secondary cusps are slightly smaller, similar to each other in size, and usually not curved (figs 169, 209). Starting from the innermost, smallest tooth, with a height of 0.022 mm, the teeth gradually increase in size to about two times that height, i.e. to 0.047 mm in the penultimate tooth, which is followed by the ultimate, usually malformed 25 th tooth, with a height of 0.040 mm (table 2). Jaw ( fig. 254; table 2). Only one jaw was studied (A. Gittenberger, 2000: 145). The denticulate edge consists of a row of slender, blunt denticles ( fig. 254). They have a maximum size of 0.0035 mm. Seen from the outside ( fig. 254), 65 denticles per 0.05 mm extend above a 0.0179 mm broad, smooth to granulated jawflap, which lies merged with the jaw over part of the jaw-pattern. The pattern under the jaw-flap consists of three or four rows of somewhat sunken, pentagonal figures, of which the lower two rows are densely pitted. Underneath this pattern the surface is smooth to granulate. The inner surface of the jaw is unknown. . Egg-capsules (fig. 282;A. Gittenberger, 2003: 140, fig. 8) ovoid, somewhat transparent, with conspicuous protuberances, not embedded with sand, 1.55-1.57 mm (mean = 1.56, n = 4) in diameter, e.g. measured horizontally, from left to right in figure 282, containing 230-415 eggs (mean = 328, n = 6) each. The mucus threads that connect the egg-capsules are strongly twisted and not sculptured ( fig. 283).
Remarks. See A. Gittenberger (2003), for a more detailed description. Here some additional data are given, with notes that may be relevant for the differentiation of this species.
Epifungium hoeksemai (A. Gittenberger and Goud, 2000) Epitonium hoeksemai A. Gittenberger and Goud, 2000: 4-6, figs 9-10, 18, 20, 26, 43.  . 104) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 22 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch ( fig.  124) has up to 11 whorls, separated by a moderately deep suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, low costae, not or barely touching the adjoining whorls, slightly curving adaperturally at the preceding whorl. Just before reaching the preceding whorl the costae become slightly coronate. The number of costae on the 2 nd , 3 rd , 5 th teleoconch whorls increases quickly (table 1). Usually this number remains approximately the same (adjoining whorls differing in about two costae) from the 6 th whorl onwards (14 of 18 specimens). However, in some shells (4 of 18) it keeps on increasing, and then the number of costae per whorl approximately doubles between the 5 th and the 8 th teleoconch whorl, reaching up to 79 on the 10 th whorl in a shell of 18.8 mm in height. The teleoconch is additionally sculptured with very low, distinct, evenly distributed spiral threads. The number of spiral threads strongly increases towards the younger teleoconch whorls, becoming numerous from about the 6 th whorl onwards. Aperture subcircular. The shells have a narrow umbilicus, which is usually visible in oblique view only.
Radula (figs 170, 190, 210; table 2). Two radulae from specimens from Palau could be studied (table  2). Each tooth has an irregularly triangular shape, starting very narrow and gradually becoming very broad towards the apical part ( fig. 170). The stem and the blade merge gradually; the blade has 1-3 acute, secondary cusps. The teeth are attached to the radular plate along the bases, which takes about ¾ of the length of a tooth (figs 170, 190, 210). The innermost tooth has one secondary cusp while all other teeth usually have two; the 11 th tooth of one of the radulae has 3 secondary cusps (table 2). The straight, acute, secondary cusps are somewhat smaller than the acute, apical cusp, which is slightly curved upwards, away from the stem (figs 170, 190, 210). Starting from the innermost, smallest tooth, with a height of 0.018 mm (n = 2), the teeth gradually increase in size to about 1½ times that height, i.e. 0.027-0.028 mm (n = 2), up to the penultimate, i.e. 17 th -18 th tooth (n = 2), after which the ultimate, somewhat smaller, 18 th -19 th tooth, with a height of 0.022-0.025 mm (n = 2) follows (table 2).
Jaw (figs 11, 255-256, 261; table 2). The denticulate edge consists of a row of slender, blunt denticles, which are basally pitted on the inside ( fig. 261). They have a maximum size of 0.0030-0.032 mm (n = 2). Seen from the outside (figs 255-256), 58-64 denticles per 0.05 mm (n = 2) extend above a 0.0074-0.0120 mm (n = 2) broad, smooth to granulated jaw-flap, which lies loosely over part of the jaw-pattern. The pattern under the jaw-flap consists of rows of pitted, sunken, pentagonal figures, gradually becoming obsolete away from the denticulate edge. On the inner surface of the jaw ( fig.  261), just below the denticles, there is a row of engraved, scarcely pitted, irregularly square-like figures, followed by an area that is somewhat granulated to smooth. . Egg-capsules ( fig. 284) ovoid, with distinct protuberances, sometimes embedded with sand, 1.11-1.85 mm (mean = 1.45, n = 6) in diameter, e.g. measured horizontally, from left to right in figure 284, containing 136-350 eggs (mean = 215.8, n = 6) each. The mucus threads that connect the egg-capsules are strongly twisted and not sculptured ( fig. 285).
Habitat. The snails and their egg-capsules were found at 1-20 m depth, associated with Heliofungia actiniformis (Quoy and Gaimard, 1833) and Fungia (Fungia) fungites (Linnaeus, 1758). They usually live attached with their mucus threads to the underside of these mushroom corals or to the hard substrata underneath. Sometimes the snails occur buried in the sand underneath the host. Most host corals were found on coral slopes.
Distribution ( fig. 81). The species is known from Indonesia and Palau.
Differentiation. Conchologically this species resembles Epifungium adgravis spec. nov., E. marki spec. nov., E. nielsi spec. nov. and E. ulu. It differs most clearly from these species by the sculpture of spiral lines, which are distinct instead of sometimes obsolete on the initial teleoconch whorls, evenly distributed instead of more prominent underneath the periphery of a whorl and increasingly more numerous in between the 2 nd and the 5 th teleoconch whorl (table 1). On average the number of spiral threads on the 5 th teleoconch whorl is much higher and the shell height/width index is lower than in the most similar species (table 1).
Remarks. For a more detailed description of the shell and the proboscis, see A. Gittenberger et al. (2000).
Here some additional data are given, with notes that may be relevant for the differentiation of this species. See also the remarks on Epifungium ulu.
from the 3 rd teleoconch whorl onwards, whereas this number decreases in the remaining 7 shells, usually on the 6 th and 7 th whorl, after which it remains approximately the same. There are up to 26 costae on a whorl; on the 8 th whorl in a shell of 8.9 mm in height. The teleoconch is additionally sculptured with very low, distinct, evenly distributed spiral threads. The number of spiral threads gradually increases towards the younger teleoconch whorls, but only rarely becomes numerous. Aperture subcircular. The umbilicus is closed.
Radula (figs 168, 171, 191, 211; table 2). Only one radula from an Indonesia snail could be studied (figs 168, 171). The stem and the blade of each tooth are very slender, similar in width and merge gradually; the blade has 2-5 acute, secondary cusps. The teeth (figs 171, 191, 211) are attached to the radular plate along the bases, which takes about half of the length of a tooth. The number of secondary cusps (table 2) gradually increases from 2 on the innermost tooth ( fig. 191, left) to 4 on the 5 th -10 th teeth, after which the penultimate and the ultimate, i.e. 12 th tooth, follow with 3 and 2 secondary cusps, respectively ( fig. 211, right). The apical cusp and the secondary cusp directly underneath it are usually similar in size and somewhat curved towards each other; all other secondary cusps are slightly smaller, similar to each other in size, and curved upwards to the preceding secondary cusp ( fig. 212). Starting from the innermost, smallest tooth, with a height of 0.018 mm, the teeth gradually increase in size to two times that height, i.e. 0.034 mm, up to the 8 th , after which they remain the same until the penultimate tooth, which is followed by the smaller, 12 th tooth with a height of 0.028 mm (table 2).
Jaw (figs 257, 262; table 2). The two jaws flanking the studied radula were studied. The denticulate edge consists of a row of slender, blunt denticles, which are basally pitted on the inside ( fig. 262). They have a maximum size of 0.0018 mm. Seen from the outside ( fig. 257), 72 denticles per 0.05 mm extend above a 0.0060 mm broad, granulated jaw-flap, which lies loosely over part of the jaw-pattern. The pattern under the jaw-flap is vague, but seems to consist of at least several rows of somewhat sunken, pentagonal figures. Most of the jaw is densely pitted, but no pits are discernable directly under the jaw-flap. On the inner surface of the jaw ( fig. 262), just below the denticles, there is a row of inconspicuous, engraved, scarcely pitted, irregularly square-like figures, followed by an area that is somewhat granulated to smooth.
Spawn ( diner, 1909, F. (C.) tenuis Dana, 1846, or F. (C.) vaughani Boschma, 1923. They usually live attached with their mucus threads to the underside of these mushroom corals. Most host corals were found on a sandy, nearly flat bottom, situated along the lower border of a steeper coral slope.
Distribution ( fig. 82). The species is known from the Indo-West Pacific, from the Maldives, Thailand, Philippines and Indonesia to Australia.
The teleoconch is additionally sculptured with irregularly placed, relatively thick, spiral threads. From the 6 th -9 th teleoconch whorl onwards, there are irregularly spaced, thin, spiral threads and incised spiral lines in between and on the major spiral threads. The number of major spiral threads increases from the 2 nd to the 5 th whorl, after which it remains almost constant. From the 7 th -9 th whorl onwards, some of the minor spirals may gradually change into thick spiral threads. Aperture subcircular. In the 5 mm high specimen with 5½ teleoconch whorls, the umbilicus is closed; in the other four, larger specimens the umbilicus is very narrow, visible in oblique view only.
Radula (figs 172, 192, 212; . 108) has 3¼-3½ whorls (n = 5); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 23 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch ( fig. 128) has up to 7½ whorls, separated by a very deep suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, not or slightly curved, low costae, not or hardly touching the adjoining whorls. The costal ribs remain similar in height along the entire whorl. The number of costae is similar on all whorls (table  1). There are up to 27 costae on a whorl; on the 7 th whorl in a shell of 6.6 mm in height. The teleoconch is additionally sculptured with very low, distinct, evenly distributed spiral threads. The number of spiral threads gradually increases towards the younger teleoconch whorls (table 1). Aperture subcircular. The umbilicus is closed.
In almost all shells the protoconch is seriously damaged, with missing whorls, or very strongly eroded. Protoconchs that still show axial lines are rare (1 out of 40). The teleoconch ( fig. 130) has up to 8½ whorls, separated by a somewhat indented suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, not or slightly curved, very low costae, which are not or hardly touching the adjoining whorls. The number of costae on the 2 nd , 3 rd , 5 th and younger teleoconch whorls usually increases considerably. There are up to 65 costae on a whorl; on the 8 th whorl in a shell of 14.2 mm in height. The teleoconch is additionally sculptured with numerous, inconspicuous spiral threads, which are usually obsolete on the initial whorls. Aperture rather roundish, its border curved in such a way that the parietal interruption is shorter than each of the three other sides, i.e. the palatal, basal and columellar side, which very gradually change into one another. Umbilicus clearly open, quickly narrowing inside.
Remarks. It seems that in both Epifungium pseudotwilae spec. nov. and E. twilae, there are many more broken and strongly eroded protoconchs than in the other epitoniids that are associated with corals. All paratypes of E. twilae that were found associated with Sandalolitha robusta and Zoopilus echinatus, have now been identified as E. pseudotwilae spec. nov. The epitoniid species collected in the Red Sea off Thomas Reef, Sinai, and identified as E. bullatum by Dushane (1988a: 30, figs 5, 6) is either E. twilae or E. pseudotwilae spec. nov. (see also A. Gittenberger et al., 2000); because the host species is un-known and since the specimen could not be studied in detail, it is impossible to conclude to which of these two species it belongs. See A.  for a comparison of "Epitonium twilae" with Epitonium bullatum.
(with egg-capsules) specimens that were found are 8-12 mm in shell height, with about 15 mm for the largest shells. However, an exceptionally large specimen ( fig. 70), collected off Bali, Indonesia, reaches 28.2 mm in height. The holotype, missing the protoconch and the initial teleoconch whorl or whorls, measures 14.2 × 5.7 mm. The protoconch ( fig. 111) has 3¼-3½ whorls (n = 10); apart from its smooth apical part, it is sculptured with regularly spaced, very fine, incised, axial lines, 25 (n = 1) per 0.2 mm on protoconch whorl 2¼-2¾. The teleoconch ( fig. 129) has up to 12¾ whorls, separated by a moderately deep suture; it is sculptured with mostly regularly placed, usually discontinuous, orthocline, lamellar, low costae, touching the adjoining whorls. From about the 5 th teleoconch whorl onwards, the costae usually become slightly coronate just before reaching the preceding whorl; they curve adaperturally while touching it. In most specimens the number of costae remains approximately the same on all whorls, with adjoining whorls differing in about two costae at most. One shell with a height 21.6 mm, has 21, 21, 21 and 22 costae on the 2 nd , 3 rd , 5 th and 11 th teleoconch whorl, respectively; on the 12 th teleoconch whorl however, there are 39 costae, the highest number recorded for Epifungium ulu. Very fine, irregularly placed, incised, axial lines are present from about the 6 th teleoconch whorl onwards. The teleoconch is additionally sculptured with very low, inconspicuous, spiral threads, which are randomly placed on the whorls and are usually obsolete on the initial whorls. Although the number of spiral threads on the 2 nd , 3 rd , and 5 th teleoconch whorls remains approximately the same (adjoining whorls differing in about two), this number usually increases slowly towards the younger whorls, sometimes becoming numerous from about the 9 th teleoconch whorl onwards. Aperture subcircular. About half of the specimens (14 out of 25) have a closed umbilicus; in the remaining 11 shells the umbilicus is very narrow, visible in oblique view only. The presence of either a closed or an open umbilicus is not correlated with shell size.
Radula (figs 174, 194, 214; table 2). The radulae of four Indonesian snails with shell heights of 9.1, 10.0, 14.0 and 28.2 mm, respectively, were studied (figs 174, 194; table 2). The radulae of the two largest snails could not be accurately counted (table 2). No distinct differences in form and/or size of the teeth, related to the size of the snails, were found. Each tooth (figs 174, 194, 214) consists of a moderately slender stem and a somewhat broader blade, which merge gradually; the blade has 2-5 acute, secondary cusps. The teeth (figs 174) are attached to the radular plate along the bases, which takes ½ to ¾ of the length of a tooth (figs 194, 214). The number of secondary cusps (table 2) gradually increases from 2 on the innermost tooth ( fig. 194, left) to 4-5 in between the 4 th -14 th tooth, after which the number decreases to 2-3 on the ultimate, i.e. 15 th tooth ( fig. 214, right). The apical cusp and the secondary cusp directly underneath it are usually similar in size and somewhat curved towards each other; all other secondary cusps are usually similar in size and somewhat curved upwards, away from the stem (figs 174, 194). Starting from the innermost, smallest tooth, with a height of 0.028-0.029 mm (n = 2), the teeth gradually increase in size to almost two times that height, i.e. 0.049-0.050 mm (n = 2), up to the 7 th -8 th tooth, after which they gradually become smaller until the penultimate, i.e. 14 th , 0.038-0.039 mm (n = 2) high tooth, which is followed by the somewhat smaller, usually malformed, ultimate tooth, with a height of 0.028 mm (n = 2) (table 2).

General discussion
Even though Bouchet and Waren (1986: 469) argue that the low amount of variation within epitoniids in general may reflect a low degree of specialization, many coral-associated, conchologically poorly differentiated epitoniids have specialized on only one or a restricted number of host species, and have large ranges, similar to those of their hosts. This adaptive radiation of coral-associated epitoniids was not noticed before because most species cannot easily or not at all be identified unequivocally on the basis of conchological characters alone. Their identities as separate gene pools are convincingly demonstrated by molecular data, however. Shell shapes and sculpture are only partially diagnostic because of interspecifically overlapping character states. In most cases, the operculum, the jaw, the radula, the spawn and/or the habitat do tell more about the identity of the species involved. These characters can also be very valuable for distinguish-ing between at least the newly described genera.
Many (sub)generic names of Epitoniidae are available (see e.g. Kilburn, 1985;Wenz, 1940). Still we found it necessary to introduce three more genus level taxa, viz. Epidendrium gen. nov., Epifungium gen. nov. and Surrepifungium gen. nov. The DNAdata indicate that these three new genera are monophyletic and most closely related to each other, indicating that a host-shift from sea-anemones to corals or vice versa has occurred only once in their evolutionary history (A. Gittenberger et al., in prep.). These new taxa are given a generic instead of a subgeneric status, because molecular data indicate that the genetic distance between the two Epitonium species E. clathrus and E. clathratulum versus the Cycloscala species C. crenulata (Pease, 1867) is smaller than the genetic distance between the three new coral-associated genera. Another reason to introduce three genera instead of a single new genus with three subgenera, is that no morphological character is known to unequivocally distinguish the combined three taxa from other epitoniid genera. The only non-molecular character known, is the association with hard corals instead of sea anemones and zoanthids.