Revision of the genus Diaphorocera Heyden, 1863 (Coleoptera, Meloidae, Cerocomini)

Diaphorocera , a Saharo-Sindian genus belonging to the tribe Cerocomini, is revised and a new synonymy is proposed. A cladistic classi ﬁ cation is proposed as well, on a set of adult morphological characters. The available bionomical records, both origi-nal and from literature, concerning phenology, elevation, habitat preference, and host plants, are summarised. Adult morphology of all species is described and ﬁ gured, the catalogue of localities with maps of distribution is reported, and a biogeographical analysis is proposed.


Introduction
The family Meloidae (Coleoptera, Tenebrionoidea) was recently revised cladistically  and four subfamilies were recognised: Eleticinae, Meloinae, Tetraonycinae and Nemognathinae (Pinto and Bologna, 1999;Bologna and Pinto, 2002). Blister beetles are phytophagous, feeding usually on leaves and/or fl owers of several plant families, and are characterised by cantharidin production and hypermetamorphic development, except in the primitive subfamily Eleticinae (Pinto et al., 1996;. Larvae feed on the provisions and larvae of Hymenoptera Apoidea, or on grasshopper (Acridoidea) eggs (Bologna, 1991).
Within the subfamily Meloinae, our interest was recently addressed to the Old World tribe Cerocomini, which is composed of fi ve genera (Bologna and Pinto, and longitudinally furrowed or carinate, the shape of mouthparts and the endophallic structure (Bologna, 1991;Turco et al., 2003).
The biology of the tribe is poorly known with the exception of some notes on host plants (Bologna, 1991), on sexual behaviour of the genus Cerocoma (Turco et al., 2003), and on larval hosts of few Cerocoma species (see Bologna, 1991 for a synthesis). Pre-imaginal stages of Cerocomini are known only for six species of Cerocoma (Di Giulio et al., 2002 for a review; Turco and Bologna, unpublished), and one Diaphorocera (Turco et al., 2006). Eggs are laid in holes dug by the female in the ground as in other Meloinae, and the fi rst instar larvae ("triungulins") are not phoretic, actively reaching the host's nest where they develop to adult stage. As far as is known, triungulins feed on larvae and honey or on eggs and food stored by Hymenoptera Aculeata (Bologna, 1991 for a review).
After the fi rst studies on the larval morphology (Di Giulio et al., 2002;Turco et al., 2006), our project was addressed to the revision of the tribe Cerocomini as a whole. The present paper is focused on the study of the genus Diaphorocera; another contribution is addressed to the classifi cation of the fi ve genera and to the revision of Anisarthrocera, Rhampholyssa and Rhampholyssodes (Turco and Bologna, unpublished); the third study will be devoted to the revision of the more speciose genus Cerocoma (Turco and Bologna, unpublished).
The genus Diaphorocera is a typical Saharo-Sindian element, distributed in the whole Northern Africa, southern Middle East (Palestine and Israel), Arabian Peninsula, and in southern Iran. This genus was never revised: Bedel (1895) published the fi rst key to the species, updated by Kaszab (1951;taken up by Dvořak, 1989), after which one new species and one new subspecies were described (Kocher, 1954;Kaszab, 1983).

Material and methods
During our fi eld researches we obtained ecological information on host plants and phenology on three species (D. chrysoprasis, D. hemprichi of both subspecies, D. johnsoni). We reared these species and we obtained the triungulin of D. chrysoprasis, described in a separate paper (Turco et al., 2006).
For the taxonomical study we examined 396 specimens representing all the Diaphorocera species, with at least one male of each species, including typical material, as reported in Table 1 For the phylogenetical analysis of the eight species of Diaphorocera we used the software PAUP 4.0 (Swofford, 2002) and 24 adult characters available for all species, selected from a larger set previously identifi ed; character 24 was not observed in D. peyerimhoffi because the dissection of types was not possible. The character matrix with the related list are given in Appendices 1 and 2. According to Bologna and Pinto (2002), the single taxon constrained as outgroup is "Anisarthrocera" semirufa (Fairmaire, 1882) (see "Classifi cation"). Autapomorphic characters were utilized for the diagnoses and key only. As expected, characters displayed some homoplasies, as indicated by relatively low consistency index (CI) (Appendix 3). Both binary and multistate characters were employed, all elaborated as unordered and equally weighted, and processed by the branch-and-bound algorithm using 'parsimony' as optimality criterion and the 'furthest' addition sequence option. The accelerated transforma- tion algorithm (ACCTRAN) was used to optimize characters on cladograms. Confi dence levels were assessed using Bootstrap Analysis and results were compared by generating a strict consensus cladogram.

Bionomics
All the species live in eremic habitats, both on dunes or stony desert (Fig. 1). Species of this genus are strictly diurnal, and adult occurrence is primarily restricted to spring, as summarised in Table 2. All the species seem to be distributed at low elevation, from sea level to about 200 m a.s.l., with a single record of D. obscuritarsis at 1200 m a.s.l. in southern Morocco. Adults feed on pollen of several plant families; all personal and literature records are summarised in Table  2. Thanatosis was observed in the fi eld in D. hemprichi, D. johnsoni and D. chrysoprasis. In this genus sexual dimorphism is evident mostly on head, antennae, and sometimes also on fore tibiae, but courtship behaviour has never been studied, and we only quickly observed on fl owers the dorsal and the subsequent linear phases of D. chrysoprasis copulation. As previously indicated, the larval hosts and the pre-imaginal development are unknown, except the triungulin of D. chrysoprasis (Turco et al., 2006).

Classifi cation
This genus was described by Heyden (1863) to include D. hemprichi from Egypt, but in the same year a second species was described by Fairmaire (1863) from the opposite side of Sahara, and Bedel (1895) evidenced defi nitively the Saharan distribution of this genus. Subsequently other representatives were found also in the Arabian peninsula and South Iran, enlarging its range, which is now similar to that of other eremic genera of animals and plants.
The phylogenetic relationships of Diaphorocera within Cerocomini were never defi ned and are the object of a separate contribution (Turco and Bologna, unpublished). Larval features of Cerocomini are until now uninformative, because of their scarcity, homogeneity, and also because pertinent to only two genera. Kaszab (1951Kaszab ( , 1969Kaszab ( , 1983 divided the genera on the base of the number of antennomeres, considering correctly the reduction as a derived condition, but he did not evaluate other derived features as those of aedeagus, fore tibiae, etc. The basic number of antennomeres of Meloidae is 11, but the reduction is common particularly in several genera of the tribe Mylabrini. Two genera of Cerocomini have 11 antennomeres, as a primitive condition: Diaphorocera and Anisarthrocera. Two other genera, namely Cerocoma and Rhampholyssodes, have 9-segmented antennae, and a fi fth genus, Rhampholyssa, has 8-segmented antennae. Bologna and Pinto (2002) supposed the separation of Anisarthrocera from Diaphorocera could be doubtful. Actually, Diaphorocera is distinct, but its relationships may be looked for examining the Anisarthrocera-complex. In fact, this last genus, considered temporarily as monophyletic by Bologna and Pinto (2002), is actually polyphyletic (Turco and Bologna, unpusblished). It includes A. batesi Marseul, 1872, a polytypic species from Iran and Arabia, which is greatly different from A. semirufa (Fairmaire, 1882) from N Somalia and a new Kenyan species, which probably belong to a new genus (Turco and Bologna, unpublished). These last two species have unmodifi ed male fore tibiae, unlike A. batesi, and are slightly similar to Diaphorocera (see also Bologna, 1991), from which they differs at least for the single hook on both aedeagus and endophallus, in addition to the body colouration. Contrarily to Kaszab (1951), frontal calli are found, more or less developed, in both Anisarthrocera-complex and Diaphorocera and cannot be used to separate them.
Waiting for the phylogenetic revision of the tribe (Turco and Bologna, unpublished), we consider Diaphorocera as a primitive genus of the tribe, together with Anisarthrocera s.str. and the new East African genus. Phenetically, this new genus seems more close to Diaphorocera than to Anisarthrocera. Relationships among Diaphorocera species derived from the cladistic analysis, are summarised in a cladogram (Fig. 2), emerging from a matrix of 8 species (and the outgroup "Anisarthrocera" semirufa) x 24 characters (Appendixes 1 and 2). This most parsimonious cladogram evidences three main lineages: one including 3 species, and the second including a single species, the last 4 species, subdivided in two minor lineages (see Table 3 for a list of synapomorphies). The main lineages represent three monophyletic groups of species recognised primarily by the shape of male fore tibiae and last antennomere: a The obscuritarsis group: D. carinicollis, D. johnsoni, D. obscuritarsis, all with last male antennomere subquadrate and fore tibiae not modifi ed. The fi rst character could be considered an apotypic condition, because blister beetles and in particular other Cerocomini, have the last antennomere elongate. The second character is plesiotypic. Relationships among the species were not resolved by the cladistic (Fig.  2), but the bootstrap analysis distinguished one clade including D. obscuritarsis and D. carinicollis by a very low confi dence value (24). b The promelaena group: D. promelaena only, characterised by the last antennomere elongate as in the hemprichi group, but distinct because of a different derived condition of the male fore tibia, modifi ed only distally, and by the integument partially black. The phylogenetic placement of this group seems to be close to the obscuritarsis group, even if supported by a relatively high consistency index (69).   Diagnosis. The genus Diaphorocera is characterised, as other Cerocomini, by a marked sexual dimorphism. Several male characters do not represent generic synapomorphies but are present in most species of the genus, as the modifi cations of fore tibiae. Because of the number (11) of antennomeres, the metallic colouration of most part of body, the presence of two hooks on both aedeagus and endophallus, Diaphorocera is easily distinguishable from any other cerocomine meloid. 6-17 mm length. Head most commonly metallic, green or blue, in one species (D. promelaena) black, in some specimens with a red spot on frons. Labrum, mandibles, and maxillae very elongate, completely or partially orange; galeae fringed. Frons of males with two smooth calli, just behind the antennae, scarcely raised (D. johnsoni) to very distinct and keeled (D. sicardi, D. peyerimhoffi ). Antennae orange or with antennomere I metallic or black; inserted on the fronto-clipeal suture, 11-segmented, subclavate in females, more or less modifi ed in males: antennomere I swollen or elongate (respectively in the main lineages); II and III cup-like; IV enlarged, anteriorly normal or bilobate; V and VI more or less enlarged; VII enlarged with or without a dorsal spine extension; VIII-X more or less enlarged and variously shaped; XI elongate or subquadrate; last antennomere similarly shaped in both sexes.
Pronotum metallic, green, blue or violet, in one species (D. promelaena) black; usually elongate, with two oblique impressions on the anterior third in males. Mesopleura not or only slightly depressed just behind the anterior margin, not touching each other; mesosternum not differentiated anteriorly; metasternum wide. Elytra metallic, green or blue, fl attened, in one species evidently sinuate on external side; wings normally developed. Coxae and trochanters yellow, black or metallic (green, blue or violet); femurs ant tibiae yellow or reddish; male fore tibiae in one lineage simple, in the other lineages with a laminar external expansion, more or less extended, or only a short infl ated expansion; tarsi not modifi ed, yellow or reddish with dark at apex or almost completely dark.
Abdomen metallic green, blue, violet, or black; posterior margin of male last abdominal sternite emarginated, rounded in females. Male genitalia with lobes of parameres elongate in some species; aedeagus with two distinct hooks, subequal in size and directed backward; endophallus with sclerotised apical portion bidentate, the apical hook smaller, and outwardly directed.
Commented catalogue. For each species the following information is indicated: the synonymies; the type locality and the type material, also for synonyms; a diagnosis and eventually some taxonomic remarks; the distribution, with the list of localities divided, from West to East, by states and districts, and with the acronym of the collection where the material is preserved and/or literature citations.
One of the females lacks right middle tarsus.
Diagnosis. Male. (Figs 3a; 4a; 5a; 6a; 7a, h; 8a-c; 12). 13-15 mm length. Body blue-violet metallic, but elytra green metallic, antennomere I dark, II darkling orange and II-XI orange, mandibles black, clypeus and labrum dark or partially reddish, maxillary palpi reddish, frons between antennal sockets black, antero-lateral portion of head, anterior to eyes, dark, femurs and tibiae orange, tarsi dark but tarsomere I of fore and middle tarsi orange and basis of II fore tarsomere reddish. A red frontal spot more or less evident. Long yellow setae on posterior and ventral portions of head, pronotum, scutellum, thoracic pleurites and fore coxae. Frontal calli small and only weakly developed, anterior portion not modifi ed, scarcely visible on lateral view, posterior margin, on dorsal view reaching about the middle of the inner margin of eye. Temples subparallel, maximum width of head on temples. Labrum about 1,5 times longer than clypeus. Maxillary palpomere III than II, distal end of III obtuse, IV slender and parallel, about 2 times as long as the width. Anterior side of antennomere III with setae longer than those on II; anterior margin of IV not bilobate, only with an elongate protrusion; anterior margin VII without appendix; spine-like setae on anterior apex of antennomeres IV-VII; posterior side of VI-IX only with short setae; antennomere VII only slighly wider than VI and slightly narrower than VIII; XI subquadrate, without chitinous and shiny lines.
Pronotum wide, robust, anteriorly slightly narrowed, maximum width on fore side slightly narrower than temples, fore oblique grooves deep and well developed; middle longitudinal smooth line well evident, forming an apparent carena. External margin of elytra posteriorly greatly sinuate.
Parameres in ventral view slender and only slightly angulated at the base of lobes; lobes elongate (ratio lobes length/parameres length: 0.39); aedeagus as in Fig. 8c.
Frontal calli small and only weakly developed, anterior portion not modifi ed, not visible on lateral view, posterior margin, on dorsal view reaching about the middle of the inner margin of eye. Temples parallel, maximum width of head on eyes. Labrum about 1,5 times as long as clypeus. Maxillary palpomere III shorter than II; distal end of III obtuse; IV slender and parallel, about 2 times as long as the width. Anterior side of antennomere III with setae as long as those on II; anterior margin of IV not bilobate, only with a short digitiform protrusion; VI with a dorsal spur; spine-like setae on anterior apex of antennomeres IV-VII, very robust on VII; anterior margin of VII without appendix; posterior side of antennomeres VI-IX only with short setae; VII distinctly wider than VI and slightly narrower than VIII; XI subquadrate, without chitinous and shiny lines, apically slightly pointed.
Pronotum slender, maximum width on fore side distinctly narrower than temples, fore oblique grooves only weakly developed. External margin of elytra posteriorly only slightly sinuate.
Four females paratypes lack some body parts: both antennae (except the fi rst two antennomeres, still present); hind right leg (except the coxa, still present); the last two tarsomeres of fore right legs (in two females).
Frontal calli not clearly visible on lateral view, posterior margin on dorsal view reaching about the middle of the inner margin of eye, anterior portion not modifi ed. Temples slightly curved, about as wide as eyes. Labrum about 1,5 times as long as clypeus. Maxillary palpomere III shorter than II; distal end of III obtuse; IV short and sub-rectangular, about 1,5 times as long as the width. Anterior side of antennomere III with few setae, distinctly shorter than those on II; anterior margin of IV not bilobate, only with a digitiform protrusion; anterior margin of VII with a dorsal slender and pointed appendix; spine-like setae on anterior apex of antennomeres V-VII; posterior side of VI-IX only with short setae; one black, chitinous and shiny line on fore margin of X and two oblique in the middle of XI; XI subquadrate.
Female. Colouration as in male but antennae, labrum and maxillary palpi dark; fore margin of labrum dark; femurs and tibiae yellow-orange. Temples wide, slightly enlarged, maximum width of head on temples. Antennomere XI subquadrate.
Frontal calli with posterior margin on dorsal view, reaching the posterior half of the margin of eye, slightly visible on lateral view; anterior portion evidently arcuate but not prolonged in the middle, externally not differentiated. Temples very elongate and parallel, slightly shorter than the longitudinal diameter of eye, the maximum width of head on eyes. Labrum about 2 times as long as clypeus. Maxillary palpomere III subequal to II; distal end of III obtuse; IV longer than twice its maximum width. Anterior side of antennomere III with few setae, about as long as those on II; anterior margin of IV, V and VII bilobate; posterior side of antennomeres III-VIII with short setae; VIII-X largely transverse and fl attened, VIII distinctly wider than the others, apically rounded, IX apically truncate, X halfmoon like; width of X distinctly shorter than the length of XI; XI elongate.
Pronotum narrow and elongate, anteriorly with two oblique and deep grooves. Fore tibiae dorsally fl attened with a laminar expansion on the external side upward curved; external spur of hind tibiae narrowly spatuled. External margin of elytra posteriorly not evidently sinuate.
Female. Colouration as in male, except mouthparts slightly darker; frons between antennal sockets and clypeus basally metallic. Temples elongate and parallel; maximum width of head on eyes. Antennomere XI elongate.
Type material. Types of the nominate subspecies were not examined; they are probably preserved at the Zoological Museum of Berlin.
Diagnosis. Male. (Figs 3h; 4h 5h; 6h; 7g, d; 8h; 9l-n; 11n). 6-12 mm length. Similar to D. chrysoprasis except for the following characters: temples shorter and slightly curved; antennomere VIII slightly wider than IX and X; anterior portion of antennomeres VIII-IX apically narrowing; width of X slightly shorter than the length of XI. Pronotum slightly wider than in male; foretibiae with a laminar expansion also on the internal side. Lobes of parameres raised at base and more diverging externally.
Diagnosis. Very similar to the nominate subspecies, being the differences, summarised by Kaszab (1983), very weak: (a) the head has a sparse puncturation in the nominate subspecies, but is almost smooth in D. hemprichi saudita; (b) the pronotum is shorter and broader in the former and more elongate and narrow in the latter, moreover the female pronotum of the Arabian race has punctures very sparse, uniform and fi ne.
Taxonomic remarks. D. hemprichi and D. chrysoprasis are very close and diffi cult to distinguish, except for the antennal and head features listed in the diagnostic key. Kaszab (1951) emphasised the difference between these species as concerns the inner side of male fore tibia. That of D. hemprichi is expanded to form a lamina (Figs 10g, p), but in the second species the inner margin is simple. Actually, in the Ain-Séfra (Algerian Sahara) population, living in syntopy with D. chrysoprasis, we found a great variability of this character, and some individuals have the inner side scarcely or not expanded.
Type material. Two males and seven females paratypes (HNHM) were examined. All the paratypes have the same following labels: "Biskra / R. Oberthür / 1875" (white with thin black frame, printed); "coll. R. Oberthür / ex coll. Deyrolle" (white, printed); "Paratypus 1876 / Diaphorocera / promelaena / Fairmaire" (white with red frame, handwritten, except "Paratypus" printed with red ink). The holotype was not found. Three females lack some parts of the body: the last two tarsomeres of hind left leg and the whole tarsus of hind right leg; the whole tarsus of hind left leg; the whole tarsus of hind right leg and tibia and tarsus of hind left leg. Diagnosis. Male. (Figs 3d;4d;5d;6d;7dm;12c). 6-10 mm length. Head, including the base of clypeus and mandibles, the remaining mouthparts black or dark, pronotum, abdomen, thoracic sternites, coxae, trochanters and antennomere I subopaque black; the rest of the body blue-green metallic with antennomere II-XI, femurs, tibiae and tarsi (or partially dark) orange. Body with white setation, particularly long on templa, pronotum and venter.
Head evidently transverse. Frontal calli bulged, evidently visible on lateral view, posterior margin, on dorsal view, reaching the posterior half of the margin of eye; anterior portion arcuate but not prolonged in the middle, externally not differentiated. Temples parallel and about as long as 2/3 of longitudinal diameter of eye; maximum width of head on eyes. Labrum about 1,5 times as long as than clypeus. Maxillary palpi III shorter than II, distal end obtuse; IV longer than twice its maximum width; anterior side of III with few setae, shorter than those on II. Anterior margin of antennomeres IV, V and VII not bilobate; posterior side of III-VIII with withish setae, particularly long on VI-VII; VII-IX very transverse variously shaped, X triangular, shorter than IX; XI elongate, about as long as 2 times the width of X.
Pronotum wide with fore half greatly curved, anteriorly with two oblique and deep grooves. Fore tibiae modifi ed, with a laminar external expansion only on its distal half; external spur of hind tibiae narrowly spatuled; claws short and curved. External margin of elytra posteriorly slightly sinuate.
The holotype lacks the right middle leg, except the coax, still present.
Diagnosis. Male. (Figs 3f; 4f; 5f; 6f; 7e, n; 9d-f; 10). 9-15 mm length. Blue-green metallic with head, thorax and abdomen darker, mandibles and frons between antennal sockets dark; clypeus, labrum, antero-lateral portion of head anterior to eyes, antennae and legs (except coxae and trochanters black and tarsi dark, posterior tibiae sometimes dark) orange; the extension of black colouration on middle and hind legs varies in some specimens, in which is extended on tarsi and most part of tibiae. Labrum with abundant and long yellowish setae.
Head transverse, with a slight depression posterior to calli and on temples, consequently vertex appears slightly bulged. Frontal calli clearly visible on lateral view; posterior margin on dorsal view reaching the posterior half of the margin of eye; anterior portion evidently arcuate and prolonged in the middle with two distinct pointed protrusions, externally differentiated with two elevated keels, apically pointed and anteriorly protruding; apexes of frontal keels slightly inwardly directed (Fig. 8f). Temples slightly enlarged, about as wide as eyes. Labrum about 1,5 times as long as clypeus, with an longitudinal laminar appendix, forming an arch, extended from the apex posteriad. Maxillary palpomere III subequal to II; distal end of III externally elongate and pointed; IV about twice as long as its maximum width and swollen after the middle. Antennomeres IV-X transverse; anterior portion of IV bilobate, basal lobe pointed and curved; anterior portion of VII with a long dorsal spine-like protrusion; VIII-IX with a fore chitinous line, X with a reticulation of chitinous lines and spots, XI with single chitinous spots at the base; VIII subfalcate, IX falcate, X widely subtrapezoidal, XI very transverse.
Pronotum elongate, subparallel sided, anteriorly slightly angulated with two oblique and deep grooves. Fore tibiae on lateral view with an external short infl ated expansion, with a corresponding internal depres-sion, on lateral view gibbose at base; external spur of hind tibiae narrowly spatuled. External margin of elytra posteriorly not evidently sinuate.
Female. Colouration as in male, except mouthparts slightly darker; frons between antennal sockets and based of clypeus metallic. Temples elongate and parallel; maximum width of head on eyes. Antennomere XI elongate.
All the specimens were in good conditions. Diagnosis. Male. (Figs 3e; 4e; 5e; 6e; 10). 13-17 mm length. Similar to D. sicardi except for the following characters: body larger in size; temples evidently wider and enlarged; frontal calli with anterior portion evidently arcuate but not greatly prolonged in the mid-dle, with externally protrusion externally directed (Fig. 8e); apex of maxillary palpomere III more pointed and IV lesser swollen; antennomere IV width basal lobe uncinate, VII bilobed, VIII-IX not falcate, X narrow and subfalcate, chitinous areas absent.
Female. Similar to D. sicardi, but body larger in size; frons with a red spot.
Taxonomic remarks. Diagnostic characters, additional to the Kocher's description (1954), were detected; they permit to clarify the phylogenetic position of this species and to discriminate it from D. sicardi. In addition to the features used in the key to the species, the following characters could be evidenced. Both species have the synapomorphic condition of frontal calli with a raised external keel. In D. peyerim- hoffi the fore margin of frontal callus is internally prolonged with a low and short protrusion, and externally by the apex of a raised keel outwardly bent (Fig. 8e); on the contrary, in D. sicardi the internal protrusion is more extended and the apex of the external keel is forwardly direct (Fig. 8f). The anterior margin of antennomere V is truncate, while in D. sicardi is pointed. Temples of D. peyerimhoffi are enlarged posteriad and slightly wider than the width of head on eye, while in D. sicardi are parallel and about as wide as the width of head on eye. Distribution (Fig. 10). Morocco. Tahiant (Kocher, 1956;MNHN); n' Thala, Tizi Talzent (ISR); Ouizret (Kocher, 1954;1956); Haut Ziz, Rich (Kocher, 1956;ISR); Mzizel (ISR); Haut Ziz, n'Zala (Kocher, 1956;ISR).

Biogeography
The entire tribe Cerocomini is primarily a South Palaearctic group, with an extension in East Africa of a new genus related to Diaphorocera (Turco and Bologna, . The most genera are West Palaearctic, and only one species of Cerocoma, C. schreberi Fabricius, 1781 is widely distributed from the Iberian Peninsula to W China. Rhampholyssa is distributed in the steppe and deserts of the Don and Turan lowlands, Rhampholyssodes is endemic to the Arabian deserts, Anisarthrocera, in the present meaning (see "Classifi cation") includes one Iraqi-Iranian species, and two East African species belong to the new undescribed genus.
Diaphorocera, is an eremic element, widely distributed from the Atlantic coasts of Western Sahara and Mauritania, through the entire Sahara and the Arabian peninsula, to the southern Palestinian area and to the dry regions of South Iran. In synthesis it is a typical Saharo-Sindian element (sensu Vigna Taglianti et al., 2000). Its possible relationships with an east African genus (Turco and Bologna, unpublished), one species of which ("Anisarthrocera" semirufa (Fairmaire, 1882) is specialised to semi-desert habitat, suggest interesting hypotheses of a common eremic ancestor of these two genera, split in the Sahara and East Africa, probably during the a more humid Pliocenic phase.   The phylogenetic relationships among the species emerging from the cladistic study, (see "Classifi cation") prompt some biogeographical considerations. The most speciose area results the Western part of Sahara, where are distributed 7 species on 8 (Figs 3-5). One species, D. hemprichi, has a wide Saharao-Sindian distribution, from Atlantic coasts to southern Iran; other species have a wide trans-Saharan range, as D. chrysoprasis, D. obscuritarsis, and possibly also D. promelaena (see "Catalogue"), being spread from Morocco to Egypt. The in-group analysis of two main phyletic lineages suggests the occurrence of late vicariance events, which split these groups in separate areas: (a) In the obscuritarsis group, one species -D. obscuritarsis -is widely distributed, but the remaining two, namely D. carinicollis and D. johnsoni, are respectively endemic to the opposite sides of the Sahara-Arabic desert. (b) In the hemprichi group, the robust clade D. sicardi-D. peyerimhoffi , includes one species more spread from Morocco to Tripolitania (D. sicardi) and the second endemic to a narrow area of the Moulouya Valley, in east Morocco.