Synoptic revision of Stenanona ( Annonaceae )

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INTRODUCTION
The genus Stenanona was described by Standley in 1929 to accommodate the unusual petal morphology of a species from Panama. The long, narrow petals with a drawn-out, caudate apex were unlike those of any other Neotropical Annonaceae known at that time. Fries (1931) re-examined the material during the course of his revisions of the genera of Annonaceae, augmenting the original description substantially to include partial fusion of the petals and a deltoid, tongue-like connective apex as important generic features. Fries's subsequent description in 1941 of a second species of Stenanona from Costa Rica was in full agreement with his initial generic conception, as reflected ultimately in his synthesis of the family Annonaceae for Die Natürlichen Pflanzenfamilien (Fries 1959). However, examination of recent collections from Colombia, Costa Rica, Honduras, Mexico, and Panama, as well as re-evaluation of three species assigned to the purportedly related genera Desmopsis Saff., Sapranthus Seem., and Reedrollinsia J.W.Walker, has resulted in a new, expanded generic concept (Schatz 1987), with the three species subsequently transferred to Stenanona (Schatz in Maas et al. 1994). With the description of a flagelliflorous species of Stenanona from Mexico (Schatz & Wendt 2004), and the description of seven new species herein, the following synoptic revision recognizes a total of fourteen species of Stenanona ranging from southern Mexico to southern Colombia.
Neither petal fusion nor the deltoid, tongue-like connective apex remains as defining generic characteristics. With the exception of two of the newly described species (S. columbiensis and S. tubiflora), all other Stenanona species here recognized differ from the two original species (S. panamensis and S. costaricensis) in possessing free petals, and several also lack the deltoid, tongue-like connective apex, instead possessing a discoid one (S. carrillensis, S. cauliflora, S. hondurensis). Westra (1985) has described both discoid and deltoid connective apices in Tetrameranthus R.E.Fr. Moreover, several of the Stenanona species exhibit an intermediate condition in having both discoid and deltoid connective apices (S. stenopetala), and/or have a deltoid connective apex oriented in the horizontal (toward the gynoecium) rather than vertical direction. Therefore, a suite of characters including overall leaf morphology, petal texture and venation, pollen morphology, and seed coat morphology (Van Setten & Koek-Noorman 1992), now better define the genus Stenanona.
Leaves of Stenanona exhibit a brochidodromous venation and an indument composed of simple, often golden brown hairs, and are borne on a distinctly swollen petiole, with the leaf base abruptly rounded and subcordate at the point of attachment with the petiole. Neither Standley nor Fries described the longitudinal venation present (sometimes faintly so) on the outer surface of the petals, which is otherwise exhibited by Mosannona and Sapranthus among the Neotropical genera of Annonaceae. Petal texture, a combination of the degree of fleshiness, thickness, and pliability, is consistent among all Stenanona species, and lies somewhat intermediate between Sapranthus (petals thin and membranous) and Desmopsis (petals thick and stiff). Flower colour of Stenanona varies from pink to wine red to deep blood red to rarely purple (S. tubiflora), with the loss of colour, i.e., white petals, either throughout or in part, exhibited by S. carrillensis, S. hondurensis and S. narinensis. In Sapranthus, petal colour ranges from light brownish to deep maroon purple or rarely cream-yellow, with one species retaining green petals (S. viridiflorus), whereas petals of Desmopsis are nearly uniformly yellow at anthesis (greenish white in D. verrucipes). In all species of Stenanona, the sepals dry a light tan, and thus contrast markedly with the much darker drying petals. The pollen of Stenanona is globose and inaperturate with a verrucate exine, whereas Sapranthus pollen is saucer-shaped and disulculate with a thin, smooth exine, and Desmopsis pollen is boat-shaped and disulculate with a finely verrucate exine (Schatz 1987). The seed coat of Stenanona species is usually flaky rugose to bullate as opposed to smooth to finely verrucate in Sapranthus and Desmopsis.
Recent molecular phylogenetic studies of Annonaceae (Mols et al. 2004) indicate strong support for the placement of Stenanona within a clade (the Miliusoid clade) of predominantly Asian genera, but also including the Mesoamerican genera Desmopsis, Sapranthus and Tridimeris.
The conservation status of each species has been assessed according to the Categories and Criteria defined by the IUCN (2001). The extreme rarity and restricted distributions of all but two species have resulted in preliminary threatened assess-ments for eleven species, all of which are known from four subpopulations or less: seven extremely narrowly distributed species (S. carrillensis, S. flagelliflora, S. hondurensis, S. panamensis, S. tuberculata, S. tubiflora, S. wendtii) are deemed Critically Endangered (CR); three slightly more widespread species on limestone (S. cauliflora, S. humilis, S. monticola) are assessed as Endangered (EN); and two poorly known species (S. columbiensis, S. narinensis) are evaluated as at least Vulnerable (VU) pending further information. Only the widespread S. costaricensis and S. stenopetala are considered to be of Least Concern (LC). Stenanona Standl. (1929)  Dwarf to small trees, rarely clonal and then spreading vegetatively by underground shoots; young branches and petiole densely covered with golden brown, erect or appressed, simple hairs. Leaves: distichous, simple, entire, shortly petiolate, exstipulate; lamina medium-sized, narrowly elliptic to narrowly obovate, membranous to chartaceous, base acute to rounded, or slightly cordate, often somewhat oblique, apex acuminate to sometimes acute, upper side glabrous or sparsely covered with white, appressed or erect hairs, lower side densely to sparsely covered with white or golden brown, erect, simple hairs (velutinous), venation brochidodromous, primary vein flat to impressed above, strongly raised below, secondary veins mostly distinct, 7-20 on either side of the primary vein, tertiary veins reticulate to percurrent. Inflorescence a rhipidium, terminal, but appearing subopposite to supra-axillary, on leafless branches, from the main trunk, basiflorous, or flagelliflorous, flowers nodding or pendulous; peduncle short (3-4 mm long), or absent; pedicels short to long (3 -190 mm long), bearing up to several minute bracts near the base. Indument: peduncle, pedicels, and outer side of bracts, sepals, and petals often densely covered with golden brown, erect hairs. Flowers actinomorphic, bisexual, perianth consisting of one whorl of sepals and two whorls of petals; sepals 3 or 4, valvate, free or basally connate, narrowly triangular to broadly ovate or triangular, mostly much smaller than the petals; petals 6 or 8, valvate, salmon pink to wine-or blood-red, purple, or cream, free or connate, and then with the margins of the inner petals fused to the inner surface of the outer petals toward their middle, margins of the outer petals free, relatively thin and only moderately fleshy, with slightly elevated longitudinal venation outside, verrucose or smooth inside, linear, apex acute, obtuse, acuminate, or caudate, the inner and outer petals subequal or unequal; torus depressed ovoid, cylindrical, or cushion-shaped; stamens few to numerous, spirally arranged, attached to the torus by a helical, thread-like fibre, extrorse, filament very short, apical part of connective expanded above the thecae, discoid, or deltoid and tongue-like, either horizontal and directed toward the gynoecium, or vertical; pollen globose, apolar, radiosymmetric, inaperturate with coarse verrucate exine sculpturing; carpels few to many (4 -120), spirally arranged, free, ovary 1-locular with 1-8 uniseriate or rarely biseriate ovules, ellipsoid to prismatic, densely covered with erect or appressed hairs, stigma globose, napiform, or pyriform, minutely tuberculatepapillate, densely to sparsely covered with erect hairs. Fruit apocarpous, composed of few to many, free monocarps, often with persistent sepals; monocarps 2 -80, berry-like, globose to ellipsoid, green, yellow, orange, to red, smooth or covered by laminar, lacerate excrescences, densely to sparsely covered with erect hairs to glabrous, rarely verrucose, wall 0.5-2 mm thick, stipes of monocarps 0 -16 mm long. Seeds 1-4(-8), lateral, ellipsoid to discoid, often flattened, seed coat usually covered with fruit wall remnants, flaky rugose to bullate, rarely smooth, ruminations spiniform to peg-shaped. Distribution -Fourteen species ranging from Mexico (Veracruz) in the north to Colombia (Nariño) in the south.

KEY TO THE SPECIES OF
Habitat & Ecology -In tropical moist forest, at a steep west-facing slope. At elevations of 340 -370 m.
Conservation status -Since its initial discovery in 1983, no additional populations of S. carrillensis have been found. With a known single population of 5 individuals, S. carrillensis can be assessed as Critically Endangered (CR D).
Note -The only known population of S. carrillensis was discovered by the first author in 1983 during the initial expedition into what is now the extension of Braulio Carrillo National Park to the southern boundary of the La Selva Biological Station of the Organization for Tropical Studies (Pringle et al. 1984). Among the Stenanona species with free petals, S. carrillensis resembles S. hondurensis most closely, from which it can be distinguished by its leaves with more numerous secondary veins, and its broader petals that are creamy white throughout.  Distribution -Mexico (Northern Chiapas and adjacent Tabasco).
Habitat & Ecology -In tropical moist forest. At elevations of 50-330 m.
Conservation status -Known from only 4 collections, S. cauliflora has an approximate Extent of Occurrence of no more than 800 km 2 and an Area of Occupancy of less than 500 km 2 , and thus can be assessed as Endangered (EN B1ab(iii)+2ab(iii)). One population is protected within the Reserva Especial de la Biosfera Selva El Ocote in Chiapas.
Notes - Walker (1971) based the genus Reedrollinsia solely on the unusual number of petals, stated to be from 7-9. Reexamination of the type material and a second flowering collection reveals that a 4-merous perianth is the normal state. The occasional flower with 7 or 9 petals is merely a developmental abnormality, often encountered in flowers of Annonaceae.
The 4-merous condition itself is not uncommon in the family, both as a consistent species-specific character, and as an occasional occurrence in normally 3-merous species, as in members of Cymbopetalum Benth. (Murray 1993, Schatz 1985. The genus Tetrameranthus R.E.Fr. is partly characterized by the 4-merous state, although both 3-and 5-merous flowers are occasionally found (Westra 1985). Kral (1960) states that in a population of Asimina tetramera Small, initially described as exclusively 4-merous, about as many 3-merous as 4-merous flowers are found.

Stenanona columbiensis
Habitat & Ecology -In tropical moist forest. At sea level. Conservation status -Stenanona columbiensis is known only from the type collection from an area that currently has no protected status. Thus, based solely on this single record, until additional information is gathered, it should be considered potentially threatened or at least Vulnerable (VU D2).
Note -The partial fusion of inner and outer petal whorls in S. columbiensis agrees with the original conception of the genus as emended by Fries (1931), and clearly places it near S. costaricensis, S. panamensis and S. tubiflora. It can be distinguished from these other species with connate petals by the degree of petal fusion (to half of their length), as well as by the shortly stipitate, oblong-ellipsoid, verrucose monocarps. Distribution -Costa Rica (Alajuela, Guanacaste, Heredia, Limón, San José) and Nicaragua (Jinotega, Zelaya).
Conservation status -Known from more than ten localities, including seven protected areas, within an Extent of Occurrence of over 41 900 km 2 , S. costaricensis can be assessed as Least Concern (LC).
Note -Stenanona costaricensis is very similar in gross floral morphology to S. panamensis. However, the bracts are smaller than those of S. panamensis, and occur opposite one other, rather than separated by at least 1 mm. In addition, S. costaricensis possesses 8 ovules arranged in two rows, vs 2 -4 ovules in a single row in S. panamensis. The most striking difference between S. costaricensis and S. panamensis is the surface of the monocarps: in S. panamensis the monocarps are smooth, whereas those of S. costaricensis are covered by lamellar, lacerate excrescences, irregularly fused together to form wing-like plates, which at first glance might be considered to be the result of disease. Distinct from the tuberculate monocarps of S. tuberculata, this unusual type of monocarp surface sculpturing is rare within Annonaceae, occurring in one species of Sapranthus from Mexico, Monocarpia borneensis, several species of Southeast Asian Uvaria and several Piptostigma species in West Africa.

Stenanona flagelliflora T.Wendt & G.E.Schatz -Map 2
Stenanona flagelliflora T.Wendt & G.E.Schatz (Schatz & Wendt 2004)   Conservation status -The known Extent of Occurrence of S. flagelliflora is 60 km 2 ; total potential EO is probably no more than double that figure, with 100 km 2 a reasonable estimate, based on topographical, climatological and substrate considerations. The Area of Occupancy within the EO is probably no more than 5 %, given the restricted nature of the habitat on the floors and lowers slopes of certain steep-sided valleys of small creeks; AO is thus rather generously estimated at 5 km 2 . There are 4 known subpopulations (3 of which are vouchered by collections). The area is under intense settlement pressure, especially on the Veracruz side of the state line, and, in addition, escaped fires in dry years such as 1998 have burned significant areas with potentially appropriate habitat. Thus, S. flagelliflora can be assessed as Critically Endangered (CR A3c+ 4ac;B1ab(i,ii)+2ab(i,ii)).
Note -From all other Stenanona species, S. flagelliflora differs markedly in being flagelliflorous, and by its ovate petals with a short, acute to acuminate apex. The lack of a long, drawnout apex would seem at first glance out of place in the genus. However, basic petal shape (minus the apex), size, venation and texture, all match nearly perfectly the inner petal whorl of the sympatric S. humilis. Leaves also resemble closely those of S. humilis. The loss of the caudate petal apex would seem to have accompanied the evolution of the highly specialized flagelliflorous habit, in which flowers are borne only centimetres above the ground. Tree 3-15 m tall; young twigs and petiole densely covered with golden brown, erect hairs (velutinous). Leaves: petiole 5-12 mm long, terete; lamina narrowly elliptic to elliptic, occasionally broadest slightly above the middle, 9 -25 by 3 -9 cm, membranous, glabrous above, densely covered with golden brown, erect hairs (velutinous) below, particularly towards the margins, base rounded to subcordate and slightly oblique, apex acute to acuminate (acumen to 15 mm long), rarely retuse through aborted development, primary vein flat to slightly impressed above, secondary veins 9-13 on either side of primary vein, flat to slightly impressed above. Inflorescence together with leaves, pseudolateral (supra-axillary, infra-axillary or leaf-opposed) to less often terminal, rarely an aggregate of 2 superposed inflorescences, rhipidium 1-3-flowered, to c. 10 flowers in succession, sympodial rachis to 12 mm long. Indument: peduncle, pedicels, and outer side of sepals, densely covered with golden brown appressed and erect hairs (velutinous), outer side of petals to rather densely to sparsely so. Flowers pendulous; peduncle (0-)2-7 mm long; pedicels slender, (75-)135-200 mm long, bearing a minute bract of c. 2 mm long at 5-25 mm from the base; sepals 4, basally connate, green, slightly recurved at anthesis, ovate to triangular, 5-8 by 2-5 mm, apex caudate; petals 8, free, in 2 subequal whorls, dark purple to wine red for the basal 1/3 and cream to ochre yellow in upper 2/3, lineartriangular, 50-80 by 2-4 mm at the base, evenly tapering to a point at the apex, the inner petals narrower; stamens white, c. 120, 1.5-2 mm long, apical part of connective discoid; carpels 25-35, ovary densely covered with golden brown, appressed and erect hairs, ovules 2, stigma pyriform, 0.8-1.2 mm long, coherent and abscising en masse. Monocarps green, turning ochre yellow in vivo (fide Maas et al. 8500), ellipsoid to globose, c. 15 by 12 mm, rather densely to sparsely covered with golden brown, appressed and erect hairs, stipes 4-7 mm long, attached somewhat obliquely to the monocarp. Seeds 1 or 2, ellipsoid, flattened, c. 10 by 7 mm. Distribution -Honduras (Atlántida and Yoro), where it is sympatric with S. tuberculata.

Stenanona hondurensis
Habitat & Ecology -In tropical, evergreen, moist forest on hills with deep soils. At elevations of 140 -330 m.
Conservation status -Known from only three localities, S. hondurensis has an Extent of Occurrence and Area of Occupancy of less than 100 km 2 in a region of Honduras where forest remnants are extremely fragmented and are currently lacking any protection. It thus qualifies as Endangered (EN B1ab(iii)+2ab(iii)).
Note -With its pendulous flowers borne on long slender pedicels, S. hondurensis most closely resembles S. carrillensis, from which it can be distinguished by its leaves with fewer secondary veins, and its narrower petals that are wine red at their base.  (Miranda)  Distribution -Mexico (Chiapas, the type locality and the Zona Uxpanapa region of southern Veracruz).

Stenanona humilis
Habitat & Ecology -In tropical moist forest, on sandy soils and soil pockets within karstic limestone. At elevations of 100-140 m.
Conservation status -With an Extent of Occurrence of less than 400 km 2 , an Area of Occupancy only a small fraction of the Extent of Occurrence due to the fragmented nature of soil pockets within the karstic limestone, and less than 5 localities (perhaps only 2 subpopulations), S. humilis can be assessed as Endangered (EN B1ab(iii)+2ab(iii)).
Habitat & Ecology -In montane rain forest. At elevations of 1000 -1250 m.
Conservation status -Known from only three localities constituting two locations, S. monticola has an Extent of Occurrence and Area of Occupancy of less than 30 km 2 in a region of Chiapas where forest remnants are extremely fragmented and are currently lacking any protection. It thus qualifies as Endangered (EN B1ab(iii)+2ab(iii)).
Note -During a recent visit to the CAS-Herbarium in San Francisco the second author noticed four collections by Dennis Breedlove, more or less resembling S. humilis at first sight. Unlike that species, though, all four Breedlove collections are noteworthy because of minute lens-like warts all over the plant. Otherwise they share the unequal and very narrow petals with both S. humilis and S. wendtii. Stenanona humilis seems to come closest but differs by petals almost twice as long as compared to the Breedlove collections (23 -44 mm vs 10-20 mm). It is clear that the latter represent an undescribed species for which the name S. monticola is proposed because it grows at a much higher elevation than S. humilis. Other  Tree 2 -3 m tall; young twigs and petiole densely covered with golden brown, erect hairs (velutinous), finally becoming glabrous. Leaves: petiole 3.5-5 mm long, somewhat swollen; lamina narrowly elliptic to narrowly obovate, 11-16 by 3 -6 cm, chartaceous, glabrous above, except for some erect hairs along primary and secondary veins, rather densely to sparsely covered with white, mainly erect hairs below, base obtuse to rounded, slightly oblique, apex long-acuminate (acumen 10-35 mm long), primary vein impressed above, secondary veins 7-9 on either side of primary vein, slightly raised above. Inflorescence together with leaves, supra-axillary, or produced from the trunk, a condensed rhipidium bearing a single flower at a time. Indument: pedicels and outer side of bracts, sepals and petals densely covered with golden brown, erect hairs (velutinous). Flowers pendulous; peduncle 3-4 mm long; pedicels c. 3 cm long, fruiting pedicels to c. 10 mm long, bearing several bracts 1-2 mm long; sepals 3, free, broadly ovate to broadly triangular, 3-4 by 2.5 mm, with 3 longitudinal veins, apex acute; petals 6, free, in 2 equal whorls, cream, linear-triangular to linear, 50-60 mm long, c. 3 mm broad at the truncate base, tapering evenly to < 1 mm broad just below the acute apex, the petals concave proximally, pressed tightly against the androecium, with fine reticulations inside marking the impressions of the stamens; stamens c. 80, c. 1 mm long, apical part of connective broadly discoid or with a horizontal, deltoid, minutely papillate-tuberculate, projecting toward the gynoecium; carpels c. 15, ovary densely covered with golden brown, erect hairs, ovules 2, uniseriate, stigma globose to napiform, c. 0.1 mm diam, minutely papillate-tuberculate. Monocarps orange in vivo, depressed globose, c. 11 mm diam, sparsely covered with erect hairs, stipes slender, 10-13 mm long. Seeds 1 or 2, depressed globose, 10-11 by 10-11 by 7-8 mm, bullate to rugose, with a shallow encircling equatorial furrow. Distribution -Colombia (Nariño).
Habitat & Ecology -In tropical moist forest. At sea level. Conservation status -Stenanona narinensis is known from only two collections, one of which was made at a CONIF field station. Given the proximity of the known collections to the Ecuador border, S. narinensis could occur in either the Cayapes Mataje Ecological Reserve or the Awa Indigenous Forest Reserve in Ecuador. Until additional information is gathered, it should be considered potentially threatened as at least Vulnerable (VU D2).
Note -On the basis of the texture of the petals, the golden brown indument on young twigs and on the primary vein abaxially, the globose, inaperturate pollen with coarse exine sculpturing, and a bullate to rugose seed coat, S. narinensis agrees well with other Stenanona species. Although petal venation is obscured in dried material, rehydrated petals clearly show longitudinal veins. The position of the inflorescence is still somewhat in doubt, as it is together with leaves and supra-axillary in the flowering collection, and produced from the trunk in the fruiting collection. Among the Stenanona species with 3-merous flowers and free, equal petals, S. narinensis is distinguished by its linear-triangular to linear petals, and relatively long and slender stipes of the monocarps.
Other specimens examined. ColoMbia, Nariño, CONIF field station 'La Espriella', c. 50 km SE of Tumaco, sea level, Maas et al. 6513 (COL,U). Distribution -Panama (the type locality in Bocas del Toro) and from just across the border in Costa Rica (Limón).

Stenanona panamensis
Habitat & Ecology -In tropical moist forest. At sea level. Conservation status -Stenanona panamensis has an extremely restricted range, with an Extent of Occurrence of less than 100 km 2 , and Area of Occupancy of no more than 10 km 2 , and has never been recollected in Panama. The protected coastal wetlands areas of Gandoca-Manzanillo in Costa Rica and San San Pond Sak in Panama may not harbour S. panamensis, which, in Costa Rica occurs inland 4 -5 km on hummocks within a mosaic of inundated, swampy areas. With only a single currently verified population, S. panamensis should be considered Critically Endangered (CR B1ab(iii)+2ab(iii)).
Note -Stenanona panamensis is most strikingly distinguished from its apparent closest relative, S. costaricensis, by its smooth monocarps, which contrast markedly with the lamellar, lacerate excrescences covering the monocarps of the latter. In flower, S. panamensis can be distinguished from S. costaricensis by its larger bracts that are alternate and separated from one another by at least 1 mm. In addition, as far as is known, flowers of S. panamensis are never borne along the main trunk as in S. costaricensis (trunciflory), but rather are borne primarily along older horizontal branches (ramiflory). Conservation status -With an Extent of Occurrence of over 50 000 km 2 , and more than 10 known locations, S. stenopetala can be assessed as Least Concern (LC).
Note -Stenanona stenopetala epitomizes the confusion surrounding generic delimitation among Desmopsis, Sapranthus, and Stenanona in Central America. Neither Fries's (1930) claim that the petals lack prominent venation, nor that they exhibit a thickness characteristic of Desmopsis are justified. Longitudinal venation is clearly evident in rehydrated petals, and the degree of fleshiness and thickness (and hence stiffness) fall well short of that characteristic of Desmopsis species, but rather agrees well with other Stenanona species. Further, pollen shows no evidence of aperture formation, unlike all Desmopsis species thus far examined (Schatz 1987). In vegetative aspects, the dark, glossy green lamina above that dries matte greyish green, as well as the dense golden brown indument of secondary veins and primary vein below, and ciliate leaf margin, are very reminiscent of S. carrillensis and S. hondurensis. Among the Stenanona species with free petals, S. stenopetala is distinguished by its mostly pinkish and relatively shortly pedicellate flowers, which are produced from the main trunk, by a usually 3-merous perianth, and by small sepals relative to the petals. Tree 3-10 m tall; young twigs and petiole densely covered with golden brown, appressed and some erect, hairs, soon glabrous. Leaves: petiole 2 -3 mm long; lamina narrowly obovate to narrowly elliptic, 5-24 by 2-8.5 cm, membranous, sparsely covered with some scattered, erect and appressed hairs along primary (and secondary) veins above, sparsely covered with appressed hairs, mainly along primary and secondary veins and margins below, base obtuse to subcordate, slightly asymmetrical, apex acute to acuminate (acumen to 30 mm long), primary vein impressed above, secondary veins (7-)11-14 on either side of primary vein, flat to slightly raised above. Inflorescences on older leafless branches or produced from the trunk, rhipidium sessile, often becoming branched, 1-or 2-flowered, to c. 8 flowers in succession, sympodial axis to 10 mm long. Indument: pedicels and outer side of sepals densely covered with golden brown, erect and appressed hairs, outer side of petals sparsely so; pedicels 2-5 mm long, to 10 mm long in fruit, borne in the axis of minute bract, bearing a second minute bract just above the base of the pedicel, soon falling off; sepals 3, dark red, free, triangular to narrowly triangular, 6-15 by 2-5 mm, with evident venation, apex acuminate to acute; petals 6, free, in 2 subequal whorls, dark red, linear-triangular, 30-45 by 2-5 mm; stamens pink, c. 75, 1.5-2 mm long, apical part of connective directed towards the centre; carpels 2-4, ovary densely covered with golden brown, appressed hairs, ovules 4, biseriate, stigma subglobose, c. 1 mm diam, subglabrous.
Habitat & Ecology -In tropical moist forest. At elevations of 140 -500 m.
Conservation status -Stenanona tuberculata is known from only 4 collections within 25 km of one another, an Extent of Occurrence of less than 30 km 2 in a region of Honduras where forest remnants are extremely fragmented and are currently lacking any protection. Based on projected continuing decline in forest cover in the region, S. tuberculata should be considered Critically Endangered (CR B1ab(iii)).
Note -Although S. tuberculata superficially resembles S. costaricensis at first glance, and shares ovaries with biseriate ovules with the latter species, the petals of S. tuberculata   Tree 2 -4 m tall; young twigs and petiole densely covered with golden brown, erect and appressed hairs (velutinous). Leaves: petiole 5-10 mm long, conspicuously swollen; lamina narrowly obovate, 25 -44 by 10 -16 cm, chartaceous, sparsely covered with white, appressed and erect hairs above and below, base rounded to cordate, apex long-acuminate (acumen 15-40 mm long), primary vein impressed above, secondary veins 16-21 on either side of primary vein, slightly prominent above. Inflorescence produced from the main trunk near the base (basiflory), the flower actually lying on the ground, a single flower at a time, to an unknown number of flowers in succession, sympodial rachis 10 -25 mm long. Indument: pedicels and outer side of sepals and petals densely covered with white to brown, erect and appressed hairs; pedicels c. 4 mm long, fruiting pedicels to 10 mm long, bearing several minute ovate to narrowly triangular bracts 1-2 mm long; sepals 3, free, green, ovate, 24-26 by 10-11 mm, with 5 slightly elevated longitudinal veins outside, apex caudate, slightly reflexed, margins involute; petals 6, purple outside, maroon inside, in 2 subequal, connate whorls, the margins of the inner petals fused to a medial keel on the inside of the outer petals to within 25 -28 mm of their apex, i.e., for approximately 3/4 of their length, therefore forming a long tube, the margins of the outer petals free, the margins of all petals involute distally beyond the point of fusion, the petals fleshy, narrowly oblong, 115 -130 by 11-15 mm, apex acute to acuminate, the medial keel along the inside of the inner petals to 0.7 cm tall, becoming highly rugose papillate-verrucate 55 mm from the base and broadening toward the base to 5 mm broad, the keel on the outer petals also papillate-verrucate at the base, all petals with a deep furrow on the outside corresponding to the keel on the inside; stamens purple to maroon, c. 35, 3-4 mm long, apical part of connective very small, deltoid, projecting toward the gynoecium; carpels c. 30, ovary densely covered with white, appressed hairs, ovules 4, uniseriate, stigma ellipsoid, c. 1.5 mm long, minutely tuberculate, glabrous, attached to the ovary obliquely by a very short style, connate into a head abscising as a unit. Monocarps green, with red mesocarp in vivo, ellipsoid to oblong-ellipsoid, 20-40 by 10-20 mm, densely verrucose, sparsely covered with appressed hairs, apex acute, with a distinct point to 2 mm long, stipes 2 -5 mm long. Seeds 4-6, globose to discoid, 10 -15 by 8 -10 by 4 -5 mm. Distribution -Panama (the Atlantic slope of San Blas, Prov. Panama).
Habitat & Ecology -In tropical moist forest. At elevations of 85-350 m.
Conservation status -The original locality of S. tubiflora along the El Llano-Cartí road has since been cleared of forest, and thus, the second locality c. 75 km to the east along the Cordillera de San Blas is the only known possibly extant locality. Pending further information, it should be considered Critically Endangered (CR B1ab(iii)+2ab(iii)).
Note -Stenanona tubiflora is probably most closely related to S. columbiensis, with which it shares leaf morphology, the cauliflorous habit, and the substantial fusion of the inner and outer petals. However, the degree of petal fusion (3/4 of the length) is unequalled in the genus, and results in a tubular flower. This flower is borne at the base of the trunk (basiflory), and lies horizontally on the ground. Within the tube, the inner petals are markedly keeled, with the keel becoming highly rugose and verrucose toward the base. Clonal shrub 0.3-1.5 m tall, spreading vegetatively by stolons in the leaf litter and duff just beneath the surface; young twigs somewhat zigzagging, with petiole densely covered with golden brown, erect hairs (velutinous), becoming less densely so with age. Leaves: petiole 1.5-3 mm long; lamina narrowly elliptic to occasionally narrowly ovate, 4-11 by 1-4 cm, membranous, occasionally somewhat falcate, glabrous above, but primary vein rather densely covered with erect hairs, secondary veins sparsely so to glabrous, sparsely to rather densely covered with erect hairs, particularly along primary vein and margins, below, base obtuse to acute, apex acute to acuminate (acumen to 15 mm long), primary vein impressed above, secondary veins 9-12 on either side of primary vein, indistinct and slightly prominent above. Inflorescences together with leaves, 1-or 2-flowered, terminal but appearing leaf-opposed or supra-axillary by overtopping of renewal shoot. Indument: pedicels and outer side of sepals and petals densely to rather densely covered with white, mainly erect hairs. Flowers pendent; pedicels 3-7 mm long, very slender, dull rose to dark red; sepals 3, free, red, triangular, 1-1.5 by 0.5-1 mm; petals 6, free, in 2 unequal whorls, green, maturing dark red, outer petals narrowly triangular, 5 -8 by 0.8-1.2 mm, with a caudate apex to 5 mm long; inner petals narrowly ovate-triangular, 9-11 by 2 mm, with a caudate apex to 7 mm long; stamens red, < 1 mm long, apical part of connective discoid; carpels not studied. Fruit not seen. Distribution -Mexico (the type locality, the Sierra de Tres Picos, in the Chimalapa region of eastern Oaxaca, and the adjacent Uxpanapa region of southern Veracruz, where it is sympatric with S. flagelliflora).
Habitat & Ecology -In tropical moist forest, on hills with deep soils. At elevations of 230 -700 m.
Conservation status -The conservation status of S. wendtii mirrors that of S. flagelliflora, with which it is sympatric. With an Extent of Occurrence of less than 100 km 2 , and projected continuing decline in the area and extent of habitat, S. wendtii should be considered Critically Endangered (CR B1ab(iii)).
Note -With its free, unequal petal whorls and clonal habit, S. wendtii is clearly most closely related to S. humilis. However, S. wendtii differs from S. humilis by its shorter pedicels, and smaller sepals and petals.