Streptaxid microcosm: the radiation of the endemic genus Pseudelma Kobelt 1904 (Gastropoda Pulmonata Streptaxidae) on Mayotte, Comores

Transcription

1 Tropical Zoology 21: , 2008 Streptaxid microcosm: the radiation of the endemic genus Pseudelma Kobelt 1904 (Gastropoda Pulmonata Streptaxidae) on Mayotte, Comores A. Abdou, I.V. Muratov and P. Bouchet Muséum National d Histoire Naturelle, 55 rue Buffon, Paris, France Received 13 August 2007, accepted 21 February 2008 Streptaxidae is a family of carnivorous tropical land snails, with extensive radiations in the Neotropics, Africa and Asia. About 40 species have been described from the Comores. The genus Pseudelma Kobelt 1904, endemic to Mayotte, is revised. Its anatomy, reported here for the first time, places it in the subfamily Enneinae, and indicates a close relationship to Maurennea Schileyko 2000 from the Comores and Mauritius. Five previously known species, and two new species, are recognized and classified in three genus-group names, Pseudelma, Fultonelma Haas 1951, and Marielma n. subgen. Species of Pseudelma have a high level of syntopy, and up to six species may co-occur at one locality. Besides Mayotte, Pseudelma had been recorded only from Madagascar, but we suggest that Pseudelma madagascariensis Fischer-Piette, Blanc & Vukadinovic 1974, described based on two shells without precise locality data, is a synonym of Elma messageri (Bavay & Dautzenberg 1904), a species from Vietnam. We thus reject its Madagascan type locality and restrict the distribution of Pseudelma to Mayotte, Comores. key words: land snails, Pseudelma, new species, new subgenus, Comores, Mayotte. Introduction Historical résumé Abbreviations and text conventions Material Species descriptions Pseudelma (Pseudelma) incisa (Morelet 1881) Pseudelma (Fultonelma) inconspicua (Morelet 1881) Pseudelma (Fultonelma) bisexigua Haas Corresponding author: Philippe Bouchet ( pbouchet@mnhn.fr).

2 124 A. Abdou, I. V. Muratov and P. Bouchet Pseudelma (Marielma) martensiana (Morelet 1881) Pseudelma (Marielma) auriculata (Morelet 1881) Pseudelma (Marielma) aurititi n. sp Pseudelma (Marielma) auribole n. sp Discussion The status of Pseudelma madagascariensis Fischer-Piette, Blanc & Vukadinovic Relationships and zoogeography Inventory and endemism Acknowledgements References Appendix: List of stations INTRODUCTION Streptaxidae is a family of carnivorous tropical land snails, with extensive radiations in the Neotropics, Africa and Asia (Schileyko 2000: ). It is the most diverse family of land snails in the Comores, most species being single-island or archipelago endemics. About 40 species have been described from Comores (Fischer-Piette & Vukadinovic 1974), and are conventionally placed in five genera: Streptaxis J. Gray 1837, Edentulina L. Pfeiffer 1855, Streptostele Dohrn 1866, Pseudelma and Gulella L. Pfeiffer The latter is by far the most speciose, with about 75% of the total Comoran streptaxid fauna. In , we resurveyed the land snail fauna of Mayotte (see Muratov et al. 2005) and documented the occurrence of about 35 species of Streptaxidae, including several undescribed ones and anatomical material of many previously known taxa. We chose to start our study of this material with the genus Pseudelma because it was the only streptaxid genus considered endemic to Mayotte (except for one spurious record which is discussed below). For a short introduction to the geography and conservation status of Mayotte in the context of the land snail survey, we refer the reader to Muratov et al. (2005). Historical résumé Based on the collections made by the resident naturalist E. Marie, five species of Pseudelma were described in 1881 in the same publication by Morelet, two of them (B. inconspicuus and B. exiguus) in Bulimus Bruguière 1789, then used as a catch-all genus for smooth, ovoid shells, and three (E. incisa, E. martensiana and E. auriculata) in Ennea H. Adams & A. Adams Smith (1893) added a sixth nominal species, Ennea (Edentulina) longula, which was later synonymized with B. inconspicuus by Ancey (1901). Late 19th century authors had differing opinions on the delimitations of streptaxid genera; Morelet s Ennea species were successively placed in the section Elma H. Adams 1866 of Streptostele (Tryon 1885: ), back in Ennea (Möllendorff 1886: 180), and in the section Elma of Ennea (Paetel 1890: 17, for E. incisa). A little later, on the basis of geographical distri-

3 The land snail genus Pseudelma in Mayotte 125 bution, Kobelt (1904a) established the section Pseudelma of Ennea to segregate the Elma-like shells of the Comores from the true Elma of South-east Asia. Pseudelma was retained as valid by Thiele (1931: 731), but as a section of Elma. The two species originally described in Bulimus then had a converging destiny. Bulimus inconspicuus was appropriately classified by Paetel (1890: 17) in the section Elma of Ennea, together with E. incisa, but his decision was apparently overlooked or ignored by most subsequent authors except Ancey. Haas (1951: 133) placed Bulimus inconspicuus and B. exiguus in a new subgenus Elma (Fultonelma) and, because of primary homonymy, replaced Bulimus exiguus Morelet 1881 with the name Elma (Fultonelma) bisexigua Haas Without stating any specific reason, Zilch (1960) raised Pseudelma to genus rank and classified it in Streptaxidae, Enneinae. Fischer- Piette & Vukadinovic (1974) reviewed the land snail fauna of the Comores and recognised as valid all five species described by Morelet, which they placed in Pseudelma with Fultonelma as a synonym. Finally, Schileyko (2000) classified Pseudelma in the subfamily Gibbinae (= Orthogibbinae), thus separating it even further from Elma, which he retained in Enneinae. It should perhaps be emphasized that the different taxonomical opinions by successive authors were based exclusively on shells, and even to a very large extent on the shells collected by Marie in the early 1880s. ABBREVIATIONS AND TEXT CONVENTIONS All descriptions are standardised, starting with the description of the shell, followed by the table of dimensions and proportions, and continuing, when applicable, with the descriptions of the external characters of cephalopodium, radula and genital apparatus. D refers to larger diameter, SD to smaller diameter (90 to D), H to shell height, LH last whorl height, AH to height of aperture, AW to width of aperture, Wn to number of whorls. Number of protoconch whorls in our measurements does not include the nucleus (the first 0.5 whorls). In the lists of the examined material, including juveniles, lv refers to live-taken specimens; dd to empty shells; for historical collections, the initial condition of the material at the time of collection is not known, and the abbreviation spm(s) designates any such specimens. Place names follow the Institut Géographique National s map of Mayotte, Série Bleue, 1:25,000 (Paris 1993). MATERIAL In total, 3 weeks were spent in the field, in March 2001 (wet season, collectors A. Abdou, P. Bouchet, and O. Griffiths) and August 2002 (dry season, collectors A. Abdou, P. Bouchet, and C. Handl), and 27 stations were surveyed, of which 21 yielded material of Pseudelma (Appendix). Living specimens and empty shells were hand picked under green foliage, on trunks and rock surfaces, and on the ground, in leaf litter, fallen palm sheaths, and under the bark of fallen trees. Leaf litter and top soil were searched for larger shells, then sieved, and the smaller fractions were sorted

4 126 A. Abdou, I. V. Muratov and P. Bouchet with the aid of a dissecting microscope. In addition, historical material was examined in the collections of The Natural History Museum, London (BMNH) and Muséum National d Histoire Naturelle, Paris (MNHN). SPECIES DESCRIPTIONS Phylum Mollusca Cuvier 1795 Class Gastropoda Cuvier 1795 Informal group Pulmonata Cuvier 1814 Clade Stylommatophora Schmidt 1855 Informal Group Sigmurethra Pilsbry 1900 Superfamily Streptaxoidea Gray 1860 Family Streptaxidae Gray 1860 Subfamily Enneinae Bourguignat 1883 Genus Pseudelma Kobelt 1904 Pseudelma Kobelt 1904a: Type species: Ennea incisa Morelet 1881, subsequent designation by Kobelt (1904b: 125). Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus partially covered by reflected columellar edge. Protoconch (~ 2 whorls) smooth or with regular microscopic spiral and radial sculpture. Teleoconch consists of 4-6 slightly convex whorls, separated by impressed denticulate suture, with variously developed axial ribs. Last whorl variously ascending towards apex, its height slightly more than half (53-67%) of shell height. Aperture pear-shaped with shortly reflected columellar, basal and palatal margins, toothless or with small parietal tubercle, often incised along the suture of preceding whorl. Columellar and upper palatal edges connected by thin transparent callus. Height mm, diameter mm. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula: rows, each row with shortly elongated marginal, narrow long lateral teeth and one variously developed (from narrow elongated to obtuse, rounded) smaller central tooth. Border between marginal and lateral teeth generally not clearly defined. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with variously developed pink or chartreuse spots and stripes. Talon (continuation of duct of prostate), enormous, more than half of length of albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus variously swollen and sometimes containing large, shelled, globular egg. Distal portion of uterus

5 The land snail genus Pseudelma in Mayotte 127 narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct. Spermatheca with small reservoir positioned next to albumen gland and with very long, thin duct alongside spermoviduct. Vas deferens thickened, entering penis at a varying distance from apex into long longitudinal furrow. Penis therefore with caecum, internally with one, two or three large longitudinal pilasters covered in places by mostly undifferentiated very small hooks. Penial retractor, as branch of columellar retractor, attached to caecum apically. Subgenus Pseudelma s. s. Diagnosis. Conchologically, Pseudelma s. s. differs from Fultonelma and Marielma by the just slightly convex whorls of protoconch with only radial microsculpture, separated by very shallow suture; by very deep incision at upper palatal region of aperture along suture of preceding whorl, with remains of upper palatal part of aperture attached to parietal wall in angular region; by shortly reflected columellar margin of aperture; anatomically by short, thickened vas deferens, which enters penis a short distance from apex, into long wide longitudinal furrow, which continues towards atrium; and by presence of tiny nodules inside penis in two places: on portion of large pilaster in front of vas deferens opening and on portion of one of smaller penial pilasters below vas deferens opening. Pseudelma (Pseudelma) incisa (Morelet 1881) (Figs 1A, 2A, 3A, 4A, 5A) Ennea incisa Morelet 1881: 221, pl. 9, fig. 14; 1883: 211. Streptostele (section Elma) incisa; Tryon 1885: 108, pl. 20, figs Ennea (section Elma) incisa; Paetel 1890: 17. Ennea (group Pseudelma) incisa; Kobelt 1904a: 29. Ennea (section Pseudelma) incisa; Kobelt 1904b: 126, pl. 18, fig. 10. Elma (section Pseudelma) incisa; Thiele 1931: 731 Pseudelma incisa; Zilch 1960: 568, fig. 1990; Fischer-Piette & Vukadinovic 1974: 49; Schileyko 2000: 788, fig. 1028A. Type material. Two syntypes (H: 10.8 D: 4.0 and H: 10.6 D: 3.9 mm), BMNH Type locality. Mayotte. Material examined. Historical material (all MNHN). Coll. Jousseaume, Mayotte, 2 spms; no collection data, 2 spms; no collection data, 2 spms; no collection data, 4 spms Survey: Mlima Mtsapéré, east slope, m, 24 lv, 3 dd; Bouéni peninsula: Boungoudranavi, 180 m, 1 lv, 8 dd; Ridge above Mtsangamboua, m, 3 dd; Mlima Choungui, m, 1 dd; Tchaourembo Range, Mt Ngouni, 450 m, 5 lv, 9 dd; Mlima Bépilipili, m, 2 lv, 4 dd; Mlima Maévadoani, above Tsararano, m, 3 dd; Mlima Mapouéra, Dzoumonyé forest reserve, ca. 250 m, 5 dd; Mlima Bénara, m, 14 dd; Dapani forest below Vatounkaridi summit,

6 128 A. Abdou, I. V. Muratov and P. Bouchet Fig. 1. All shells of Pseudelma at the same scale, except 1F (left) enlarged twice to show details. A, P. (Pseudelma) incisa (Morelet 1881) [Tchaourembo Range, Mt Ngouni, alt. 450 m]. B, P. (Fultonelma) inconspicua (Morelet 1881) [Mlima Bénara, alt m]. C, P. (Fultonelma) bisexigua Haas 1951 [Mlima Combani, alt m]. D, P. (Marielma) martensiana (Morelet 1881) [Tchaourembo Range, Mt Ngouni, alt. 450 m]. E, P. (Marielma) auriculata (Morelet 1881) [Mlima Tchaourembo, alt m]. F, P. (Marielma) aurititi n. sp., holotype [Boungoudranavi, alt. 180 m]. G, P. (Marielma) auribole n. sp., holotype [Mlima Mtsapéré, alt m].

7 The land snail genus Pseudelma in Mayotte m, 4 dd; Vahibéni, valley of the Gouloué river, 100 m, 1 dd; Mlima Tchaourembo, m, 13 dd; Mlima Mtsapéré, ridge crest, m, 7 dd. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus partially covered by reflected columellar edge. Protoconch (~ 2 non-convex whorls) with regular microscopic radial sculpture. Teleoconch consists of 5 slightly convex whorls, separated by slightly shouldered, impressed denticulate suture, with narrow axial ribs better developed just below suture; width of ribs approximately same as width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height slightly more than half (about 64%) of shell height. Aperture pear-shaped with shortly reflected columellar, basal and palatal margins, with obtuse columellar tooth, deeply incised along the suture of preceding whorl with remains of upper palatal part of aperture attached to parietal wall in angular region. Columellar and upper palatal edges connected by thin transparent callus. Dimensions and proportions of 18 adult specimens: see Table 1. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula (specimen from Mlima Mtsapéré, east slope, m): ~115 rows, each with shortly elongated marginal teeth, narrow long lateral teeth and one smaller, narrow, long central tooth. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with a few light pink spots and stripes. Anatomical description based on 2 individuals from Mlima Mtsapéré, east slope, m. Talon (continuation of duct of prostate), enormous, about half of length of albumen gland and passing alongside it. Free oviduct and vagina very short. Table 1. Dimensions (in mm) and proportions of 18 adult specimens of Pseudelma incisa (Morelet 1881) (2 syntypes, 4 from historical collections, 4 from Mt Ngouni, 450 m, and 8 from Mlima Bénara, m). Syntypes Mean (n = 18) Range Standard deviation H LH D SD H/D H/SD AH AW Wn

8 130 A. Abdou, I. V. Muratov and P. Bouchet Proximal part of uterus narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus slightly swollen. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct. Spermatheca with small, centrally constricted reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens short, thickened, enters penis obliquely, a short distance from apex, into long wide longitudinal furrow, which continues towards atrium as well as towards apex. Penis therefore with short caecum. Internally penis with one very large pilaster in proximal portion and two additional smaller pilasters in distal portion. Large portion of proximal pilaster in front of vas deferens opening and portion of one of the smaller distal pilasters covered with tiny nodules with very small unicuspid hook on each nodule. Most of rest of internal surface of penis, including remaining portion of first smaller pilaster, second smaller pilaster and distal portion of larger one, covered by undifferentiated very small hooks without nodules at bases. Areas around and below vas deferens entrance as well as distal part of penis are free of hooks. Penial retractor, as branch of columellar retractor, attached to caecum apically. Fultonelma Haas 1951: 133. Subgenus Fultonelma Haas 1951 Type species: Bulimus inconspicuus Morelet 1881, by original designation. Diagnosis. Conchologically, Fultonelma differs from Pseudelma s.s. and Marielma by the convex whorls of its protoconch sculptured with radial as well as more delicate spiral microsculpture; by the impressed, but not shouldered, denticulate suture; by the straight, shortly reflected upper palatal region of aperture without any incision; by having radula with fewer teeth, rows, each with shortly elongated marginal teeth, long, narrow lateral teeth and much smaller, obtuse, rounded or shortly elongated central tooth; anatomically by the short vas deferens, which enters the penis approximately in the middle part, into a long longitudinal furrow resulting from the continuation of the duct of the vas deferens towards penis tip. Pseudelma (Fultonelma) inconspicua (Morelet 1881) (Figs 1B, 2B, 3B, 4B, 5B) Bulimus inconspicuus Morelet 1881: 218, pl. 9, fig. 4; 1883: 210. Synonym: Ennea (Edentulina) longula Smith 1893: 643, fig. 2. Ennea (section Elma) inconspicua; Paetel 1890: 17. Ennea inconspicua; Ancey 1901: 220. Edentulina longula; Kobelt 1905: 305, pl. 36, fig. 19. Edentulina inconspicua; Kobelt 1905: 306, pl. 36, figs Elma (Fultonelma) inconspicua; Haas 1951: 133. Pseudelma inconspicua; Fischer-Piette & Vukadinovic 1974: 50; Schileyko 2000: 788, fig. 1028B.

9 The land snail genus Pseudelma in Mayotte 131 Type material. Bulimus inconspicuus: 3 syntypes (H: 15.7 D: 6.2, H: 16.1 D: 6.1, and H: [tip broken] D: 6.3 mm), BMNH ; Ennea longula: 2 syntypes (H: 15.8 D: 6.5 and H:? [broken] D: ~ 5.9 mm), BMNH a. Fig. 2. Apices and details of teleoconch sculpture. A, P. (Pseudelma) incisa (Morelet 1881) [Tchaourembo Range, Mt Ngouni, alt. 450 m]. B, P. (Fultonelma) inconspicua (Morelet 1881) [Mlima Bénara, alt m]. C, P. (Fultonelma) bisexigua Haas 1951 [Mlima Combani, alt m]. D, P. (Marielma) martensiana (Morelet 1881) [Tchaourembo Range, Mt Ngouni, alt. 450 m]. E, P. (Marielma) auriculata (Morelet 1881) [Mlima Tchaourembo, alt m]. F, P. (Marielma) aurititi n. sp., holotype [Boungoudranavi, alt. 180 m]. G, P. (Marielma) auribole n. sp., paratype and holotype [Mlima Mtsapéré, alt m]. Scales: 1 mm.

10 132 A. Abdou, I. V. Muratov and P. Bouchet Type locality. Mayotte (for both nominal species). Material examined. Historical material (all MNHN). Coll. Denis, Mayotte, 1 spm; no collection data, 1 spm; no collection data, 3 spms; no collection data, 1 spm Survey: Right bank of the Mroni Rouaka river, m, 2 lv; Mlima Mtsapéré, east slope, m, 17 lv, 4 dd; Tchaourembo Range, Mt Ngouni, 450 m, 24 lv, 5 dd; Mlima Bépilipili, m, 2 dd; Mlima Bénara, m, 8 dd; Mlima Tchaourembo, m, 1 dd; Mlima Mtsapéré, ridge crest, m, 4 dd. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus partially covered by reflected columellar edge. Protoconch (~ 2 whorls) with regular microscopic radial and more delicate spiral sculpture. Teleoconch consists of 6 slightly convex whorls, separated by impressed denticulate suture, with narrow axial ribs; width of ribs approximately same as width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height slightly more than half (about 57%) of shell height. Aperture pear-shaped with widely reflected columellar and shortly reflected basal and palatal margins, often with oblique columellar fold and with just traces of small obtuse parietal tubercle. Columellar and upper palatal edges connected by thin transparent callus. Dimensions and proportions of 13 adult specimens: see Table 2. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula (specimen from Tchaourembo Range, Mt Ngouni, 450 m): 46 rows, each with shortly elongated marginal teeth, long, narrow lateral teeth and a much smaller, shortly elongated central tooth. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with numerous bright pink spots and stripes. Table 2. Dimensions (in mm) and proportions of 13 adult specimens of Pseudelma inconspicua (Morelet 1881) (2 syntypes of B. inconspicuus, 1 syntype of E. longula, 3 from historical collections, 3 from Mt Ngouni, 450 m, and 4 from Mlima Bénara, m). Syntype of longula Syntypes of inconspicuus Mean (n = 13) Range Standard deviation H LH D SD H/D H/SD AH AW Wn

11 The land snail genus Pseudelma in Mayotte 133 Anatomical description based on 2 individuals from Mlima Mtsapéré, east slope, m. Talon (continuation of duct of prostate), enormous, about the same length as albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus very swollen and sometimes containing large, shelled, globular egg. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct. Spermatheca with small reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens short, thickened, entering penis obliquely some distance from apex into long longitudinal furrow resulting from the continuation of the duct of vas deferens towards apex. Penis therefore with long caecum. Internally penis with one large longitudinal pilaster covered in middle part of penis by undifferentiated very small hooks and positioned close to vas deferens opening. Area opposite vas deferens opening bears slightly larger unicuspid hooks gradually diminishing towards atrium and towards apex. Penial retractor, as branch of columellar retractor, attached to caecum apically. Remarks. Differs from P. (F.) bisexigua by its much larger (about twice as large) and proportionally higher shell, by having an obsolete parietal tubercle and by frequently having an oblique columellar fold. When he described Ennea longula, Smith (1893: 643) did not compare it to Pseudelma inconspicua, probably because the latter was then still buried in the chaos of the genus Bulimus. However, Ennea longula was soon after synonymized with B. inconspicuus by Ancey (1901: 220), a decision that Kobelt (1905: 306) did not entirely endorse, listing the two separately because he had not been able to examine the type material of E. longula. Our examination of the type material of the two nominal species shows that it falls within the range of variation of a single taxonomical species, and we confirm Ancey s synonymization. Pseudelma (Fultonelma) bisexigua Haas 1951 (Figs 1C, 2C, 3C, 4C, 5C) Bulimus exiguus Morelet 1881: 218, pl. 9, fig. 6; 1883: 210. Junior primary homonym of Bulimus exiguus Reeve 1850: pl. 88, fig Ennea exigua; Ancey 1901: 220. Elma (Fultonelma) bisexigua Haas 1951: 134. Pseudelma bisexigua; Fischer-Piette & Vukadinovic 1974: 50. Type material. Three syntypes (H: 8.0 D: 3.5, H: 8.1 D: 3.3, and H: [tip broken] D: 3.4 mm), BMNH Type locality. Mayotte. Material examined. Historical material (MNHN, all labelled Mayotte ). Coll. de Morgan, 5 spms; Coll. Jousseaume, 1 spm; Coll. H. Fischer ex Coll. Crosse ex E.

12 134 A. Abdou, I. V. Muratov and P. Bouchet Fig. 3. Radular ribbons and details; the arrows indicate the position of the central tooth. A, P. (Pseudelma) incisa (Morelet 1881) [Mlima Mtsapéré, alt m]. B, P. (Fultonelma) inconspicua (Morelet 1881) [Tchaourembo Range, Mt Ngouni, alt. 450 m]. C, P. (Fultonelma) bisexigua Haas 1951 [Mlima Mtsapéré, alt m]. D, P. (Marielma) martensiana (Morelet 1881) [Same as Fig. 3C]. E, P. (Marielma) auriculata (Morelet 1881) [Right bank of the Mroni Rouaka river, m]. Marie, 2 spms Survey. Right bank of the Mroni Rouaka river, m, 10 dd; Mlima Mtsapéré, east slope, m, 2 lv, 6 dd; Bouéni peninsula: Boungoudranavi, 180 m, 1 lv, 4 dd; Mlima Combani, m, 1 lv, 9 dd; Mlima Choungui, m, 3 dd; Tchaourembo Range, Mt Ngouni, 450 m, 9 dd; Mlima Bépilipili, m, 6 dd; Sohoa/Choungui, m, 1 dd; Majimbini forest reserve, m, 4

13 The land snail genus Pseudelma in Mayotte 135 dd; Mlima Maévadoani, above Tsararano, m, 4 lv, 15 dd; Mlima Bénara, m, 2 lv, 12 dd; Dapani forest below Vatounkaridi summit, 200 m, 11 dd; Campus of Coconi Agriculture Station, m, 1 dd; Vahibéni: valley of the Gouloué river, 100 m, 7 dd; Mlima Tchaourembo, m, 23 dd; Mlima Mtsapéré, ridge crest, m, 3 dd. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus partially covered by reflected columellar edge. Protoconch (~ 2 whorls) with regular microscopic radial and more delicate spiral sculpture. Teleoconch consists of 5 slightly convex whorls, separated by impressed denticulate suture, with narrow axial ribs; width of ribs approximately same as width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height slightly more than half (about 61%) of shell height. Aperture pear-shaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle. Columellar and upper palatal edges connected by thin transparent callus. Dimensions and proportions of 17 adult specimens: see Table 3. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula (animal from Mlima Mtsapéré, east slope, m): ~ 60 rows, each with 10 shortly elongated marginal teeth, 10 narrow long lateral teeth and much smaller, obtuse, rounded central tooth. Border between marginal and lateral teeth not clearly defined. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with variously developed pink or chartreuse spots and stripes. Anatomical description based on an individual from Mlima Maévadoani, above Tsararano, m. Table 3. Dimensions (in mm) and proportions of 17 adult specimens of Pseudelma bisexigua Haas 1951 (3 syntypes, 7 from historical collections, and 7 from Mlima Combani, m). Syntypes Mean (n = 17) Range Standard deviation H LH D SD H/D H/SD AH AW Wn

14 136 A. Abdou, I. V. Muratov and P. Bouchet Talon (continuation of duct of prostate), enormous, about half of length of albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus very swollen. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct. Spermatheca with small reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens short, thickened, entering penis obliquely some distance from apex into long longitudinal furrow resulting from the continuation of the duct of vas deferens towards apex. Penis therefore with long caecum. Internally penis with one large longitudinal pilaster positioned close to vas deferens opening. This pilaster covered near vas deferens opening by undifferentiated very small hooks. Area slightly below vas deferens opening and corresponding portion of longitudinal pilaster bears same tiny hooks gradually diminishing towards atrium and towards apex. Penial retractor, as branch of columellar retractor, attached to caecum apically. Remarks. Differs from P. (F.) inconspicua Morelet 1881 by its much smaller (about 2 times) and proportionally wider shell, by normally developed parietal tubercle and by the just slightly curved columellar margin of aperture, always without oblique fold. Subgenus Marielma n. subgen. Type species: Ennea auriculata Morelet Etymology. After E. Marie, a French Navy administration officer, who, as a resident of Mayotte in , made land snail collections on Mayotte that remained unsurpassed until our survey of Description. Shell translucent, from whitish or pale-corneous brown to almost colourless, elongated-ovate, with very narrow umbilicus. Protoconch (~ 2 whorls) with indistinct microscopic radial sculpture. Teleoconch consisting of 5-6 slightly convex whorls, with wide or narrow axial ribs, separated by impressed, shouldered, denticulate suture. Last whorl height more than half (about 53-67%) of shell height, slightly ascending towards apex near aperture. Aperture pear-shaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle, incised along the suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region. Posterior part of cephalopodium rounded above, not keeled, without fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula: rows, each with shortly elongated marginal teeth, narrow, long lateral teeth and a much smaller, narrow central tooth. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with variously developed pink spots and stripes.

15 The land snail genus Pseudelma in Mayotte 137 Talon (continuation of duct of prostate) extremely large, of about the same length as albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus not very narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus swollen. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consisting of compound gland of large acini and undifferentiated gland along prostate duct with numerous latitudinal folds. Spermatheca with small reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens long, entering penis obliquely at a very short distance from apex. Penis therefore with very short caecum, internally with 1-2 longitudinal pilasters and covered in places by undifferentiated very small hooks. Penial retractor, as branch of columellar retractor, attached to caecum apically. Remarks. Conchologically, Marielma differs from Pseudelma s.s. and Fultonelma by the convex whorls of the protoconch bearing only radial microsculpture; by the impressed, distinctly shouldered and denticulate suture; by the deep incision at upper palatal region of aperture along suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region; anatomically by the long penis and very short penial caecum. Pseudelma (Marielma) martensiana (Morelet 1881) (Figs 1D, 2D, 3D, 4D, 5D) Ennea martensiana Morelet 1881: 222, pl. 9, fig. 12; 1883: 211. Streptostele (Elma) martensiana; Tryon 1885: 109, pl. 20, fig. 47. Ennea (Pseudelma) martensiana; Kobelt 1904b: 126, pl. 18, fig. 11. Pseudelma martensiana; Fischer-Piette & Vukadinovic 1974: 50. Type material. Two syntypes (H: 13.7 D: 5.5 and H: 14.3 D: 5.7 mm), BMNH Type locality. Mayotte. Material examined. Historical material (all MNHN, from Mayotte). Coll. de Morgan, 1 spm; Coll. Jousseaume, 1 spm; Achat Vimont 1883, 1 spm and 2 damaged dd; Coll. H. Fischer ex Coll. Crosse ex E. Marie, 1 spm; no collection data, 2 spms Survey: Mlima Mtsapéré, east slope, m, 2 lv, 2 dd; Mlima Combani, m, 10 dd; Tchaourembo Range, Mt Ngouni, 450 m, 2 dd; Mlima Bépilipili, m, 1 lv, 1 dd; Majimbini forest reserve, m, 1 lv; Mlima Maévadoani, above Tsararano, m, 4 dd; Mlima Mapouéra, Dzoumonyé forest reserve, ca 250 m, 3 dd; Mlima Bénara, m, 6 dd; Vahibéni: valley of the Gouloué river, 100 m, 3 dd; Mlima Tchaourembo, m, 28 dd; Mlima Mtsapéré, m, 1 dd. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus. Protoconch (~ 2 whorls) with indistinct microscopic radial sculpture. Teleoconch consists of 5-6 slightly convex whorls, separated by impressed, shouldered denticulate suture, with faint spiral sculpture just below suture and with narrow axial

16 138 A. Abdou, I. V. Muratov and P. Bouchet ribs on entire whorl; width of ribs less than width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height is more than half (about 64%) of shell height. Aperture pear-shaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle, deeply incised along the suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region. Dimensions and proportions of 21 adult specimens: see Table 4. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Radula (animal from Mlima Mtsapéré, east slope, m): ~103 rows, Fig. 4. Genital apparatus. p: penis, s: spermatheca, t: talon. A, P. (Pseudelma) incisa (Morelet 1881) [Mlima Mtsapéré, alt m]. B, P. (Fultonelma) inconspicua (Morelet 1881) [Same as Fig. 4A]. Uterus contains egg. C, P. (Fultonelma) bisexigua Haas 1951 [Mlima Maévadoani, above Tsararano, alt m]. D, P. (Marielma) martensiana (Morelet 1881) [Mlima Mtsapéré, alt m]. E, P. (Marielma) auriculata (Morelet 1881) [Right bank of the Mroni Rouaka river, m].

17 The land snail genus Pseudelma in Mayotte 139 each with 24 shortly elongated marginal teeth, 42 narrow long lateral teeth and a much smaller, narrow central tooth. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with variously developed pink spots and stripes. Anatomical description based on 1 individual from Majimbini forest reserve and 1 individual from Mlima Mtsapéré, east slope, m. Talon (continuation of duct of prostate), enormous, about same length as albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus not very narrow, with numerous latitudinal Fig. 5. Internal structure of penis. Dots illustrate tiny hooks, each dot is a single hook. Details of specimens from same origin as those on Fig. 4. A, P. (Pseudelma) incisa (Morelet 1881). B, P. (Fultonelma) inconspicua (Morelet 1881). C, P. (Fultonelma) bisexigua Haas D, P. (Marielma) martensiana (Morelet 1881). E, P. (Marielma) auriculata (Morelet 1881).

18 140 A. Abdou, I. V. Muratov and P. Bouchet Table 4. Dimensions (in mm) and proportions of 21 adult specimens of Pseudelma martensiana (Morelet 1881) (2 syntypes, 3 from historical collections, 2 from Mt Ngouni, 450 m, and 14 from Mlima Tchaourembo, m). Syntypes Mean (n = 21) Range Standard deviation H LH D SD H/D H/SD AH AW Wn folds, connected to base of talon. Medium portion of uterus very swollen. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct with numerous latitudinal folds. Spermatheca with small reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens long, thickened, entering penis obliquely a very short distance from apex into space between proximal portions of large pilaster, shaped like an inverted noose. Penis therefore with very short caecum, internally with large, long noose-shaped longitudinal pilaster and covered by undifferentiated very small hooks around vas deferens opening and in distal but not in middle part. Penial retractor, as branch of columellar retractor, attached to caecum apically. Remarks. Conchologically, differs from all other three species of subgenus by narrow axial ribs on teleoconch (width of ribs less than width of intercostal spaces). Differs from another anatomically known species of subgenus by internal structure of penis (internal penial pilaster shaped like an inverted noose), which is quite different in P. (M.) auriculata (see below). Pseudelma (Marielma) auriculata (Morelet 1881) (Figs 1E, 2E, 3E, 4E, 5E) Ennea auriculata Morelet 1881: 224, pl. 9, fig. 13; 1883: 210. Streptostele (Elma) auriculata; Tryon 1885: 109, pl. 20, fig. 42. Ennea (Pseudelma) auriculata; Kobelt 1904b: 127, pl. 18, fig. 12. Pseudelma auriculata; Fischer-Piette & Vukadinovic 1974: 51. Type material. Two syntypes (H: 8.9 D: 3.5 and H: 8.7 D: 3.5 mm), BMNH

19 The land snail genus Pseudelma in Mayotte 141 Type locality. Mayotte. Material examined. Historical material (MNHN). Mayotte, Coll. de Morgan, 1 spm; Mayotte, no collection data, 1 spm Survey: Right bank of the Mroni Rouaka river, m, 1 lv, 1 dd; Mlima Mtsapéré, east slope, m, 2 dd; Bouéni peninsula: Boungoudranavi, 180 m, 10 dd; Ridge above Mtsangamboua, m, 1 dd; Mlima Combani, m, 13 dd; Mlima Choungui, m, 7 dd; Tchaourembo Range, Mt Ngouni, 450 m, 10 dd; Mlima Bépilipili, m, south slope, 1 dd.; Mlima Maévadoani, above Tsararano, m, 21 dd; Mlima Bénara, m, 15 dd; Dapani forest below Vatounkaridi summit, 200 m, 10 dd; Vahibéni: valley of the Gouloué river, 100 m, 4 dd; Mlima Tchaourembo, m, 34 dd; Mlima Mtsapéré, ridge crest, m, 3 dd. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus. Protoconch (~ 2 whorls) with indistinct microscopic radial sculpture. Teleoconch consists of 5-6 slightly convex whorls, separated by impressed, distinctly shouldered denticulate suture, with wide axial ribs; width of ribs more than width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height is more than half (about 60%) of shell height. Aperture pearshaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle, deeply incised along the suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region. Dimensions and proportions of 21 adult specimens (including two syntypes and the historical material from MNHN): see Table 5. Posterior part of cephalopodium rounded above, not keeled, without any fossula. Sole undivided. Head with short proboscis. Jaw not present. Table 5. Dimensions (in mm) and proportions of 21 adult specimens of Pseudelma auriculata (Morelet 1881) (2 syntypes, 2 from historical collections, and 17 from Mlima Tchaourembo, m). Syntypes Mean (n = 21) Range Standard deviation H LH D SD H/D H/SD AH AW Wn

20 142 A. Abdou, I. V. Muratov and P. Bouchet Radula (animal from Mroni Rouaka river bank): ~ 90 rows, each with ~ 10 shortly elongated marginal teeth, ~ 30 narrow long lateral teeth and one much smaller, narrow central tooth. Genital opening shortly below pneumostome. Mantle and retractors of tentacles with variously developed pink spots and stripes. Anatomical description based on 1 individual from Mroni Rouaka river bank. Talon (continuation of duct of prostate), extremely large, about same length as albumen gland and passing alongside it. Free oviduct and vagina very short. Proximal part of uterus not very narrow, with numerous latitudinal folds, connected to base of talon. Medium portion of uterus very swollen. Distal portion of uterus narrow, with thin walls and undifferentiated longitudinal folds. Prostate consists of compound gland of large acini and undifferentiated gland along prostate duct with numerous latitudinal folds. Spermatheca with small reservoir positioned next to albumen gland and very long, thin duct alongside spermoviduct. Vas deferens long, thickened, entering penis obliquely a very short distance from apex at base of proximal part of large longitudinal pilaster. Penis therefore with very short caecum. Internally penis with narrow, long longitudinal pilaster in proximal part, that enlarges towards atrium and terminates in middle part of penis as a small obtuse stimulator. Middle portion of penis with larger longitudinal pilaster that continues to atrium. Area below stimulator and proximal part of distal pilaster covered by undifferentiated very small hooks. Portion of proximal pilaster just above stimulator with few lines of slightly larger unicuspid hooks. Penial retractor, as branch of columellar retractor, attached to caecum apically. Remarks. Conchologically, P. auriculata differs from P. martensiana by having broader axial ribs (ribs broader than interspaces), and anatomically by having small stimulator in proximal part of penis. Shells of P. auriculata have an adult size intermediate between but not overlapping with, the sizes of the other two species of P. (Marielma): height mm (mean 9.0 mm) vs height mm (mean 5.5 mm) for P. aurititi and height mm (mean 12.8 mm) for P. auribole. Pseudelma (Marielma) aurititi n. sp. (Figs 1F, 2F) Type material. Holotype (dd) from the type locality; 1 paratype (dd) from Mlima Choungui and 1 paratype (dd) from Sazilé, Rassi Maoussi. All in MNHN. Type locality. Mayotte, Bouéni peninsula: Boungoudranavi. Forest at base of cliff, S, E, alt. 180 m. Other material examined. Mayotte, Survey. Type locality, 2 dd (1 damaged); Mlima Choungui, southern slope, m, 1 dd (paratype); Between Moutsamoudou and Cape Sazilé, 3-20 m, 1 dd (damaged); Mlima Maévadoani, above Tsararano, m, 6 dd; Sazilé, Rassi Maoussi, 5-30 m, 1 dd (paratype). All these localities are in the southern half of the island.

21 The land snail genus Pseudelma in Mayotte 143 Table 6. Dimensions (in mm) and proportions of 5 adult specimens of Pseudelma aurititi n. sp. (the type series and 2 from Mlima Maévadoani). Holotype Paratypes Mean (n = 5) Range Standard deviation H LH D SD H/D H/SD AH AW Wn Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus. Protoconch (~ 2 whorls) with indistinct microscopic radial sculpture. Teleoconch consists of 5 slightly convex whorls, separated by impressed, distinctly shouldered denticulate suture, with wide axial ribs often (including type) better developed just below suture; width of ribs more than width of intercostal spaces. Last whorl near aperture very slightly ascending towards apex, its height is more than half (about 60%) of shell height. Aperture pear-shaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle, deeply incised along the suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region. Dimensions and proportions of 5 adult specimens (including the type series): see Table 6. Remarks. Conchologically, differs from P. (M.) martensiana by wide axial ribs on teleoconch (ribs broader than their interspaces) and from P. (M.) auriculata and P. (M.) auribole by a much smaller (1/3-1/2 of their height) adult shell size, with less pronounced axial sculpture. Etymology. From the Latin auris, meaning ear, and the local Chimaoré language titi, meaning small; with reference to the overall appearance of the shell; used as a noun in apposition. Pseudelma (Marielma) auribole n. sp. (Figs 1G, 2G) Type material. Holotype (dd) and 1 paratype (dd) from the type locality; 2 paratypes (dd) from ridge above Mtsangamboua, 1 paratype (dd) from small crest west of Hachiroungou. All in MNHN.

22 144 A. Abdou, I. V. Muratov and P. Bouchet Type locality. Mayotte, Mlima Mtsapéré. Low forest on ridge crest, S, E, alt m. Description. Shell translucent, from whitish or pale-corneous brown to colourless, elongated-ovate, with very narrow umbilicus. Protoconch (~ 2 whorls) with indistinct microscopic radial sculpture. Teleoconch consists of N 5 km Hachiroungou Mtsangamboua Mapouéra Majimbini Mtsapéré, ridge crest Mtsapéré Combani Sohoa/Choungui Coconi Mroni Rouaka Vahibéni Maévadoani Ngouni Tchaourembo Bénara Bépilipili Boungoudranavi Choungui Dapani Rassi Maoussi Between Moutsamoudou and Cape Sazilé Fig. 6. Map of Mayotte with stations that yielded (filled stars) and did not yield (open stars) material of Pseudelma.

23 The land snail genus Pseudelma in Mayotte 145 Table 7. Dimensions (in mm) and proportions of 3 adult specimens of Pseudelma auribole n. sp. (from the type series). Holotype Paratypes Mean (n = 3) Range Standard deviation H LH D SD H/D H/SD AH AW Wn slightly convex whorls, separated by impressed, distinctly shouldered denticulate suture, with wide axial ribs; width of ribs more than width of intercostal spaces. Last whorl near aperture slightly ascending towards apex, its height slightly more than half (about 57%) of shell height. Aperture pearshaped with widely reflected columellar and shortly reflected basal and palatal margins, with small obtuse parietal tubercle, deeply incised along the suture of preceding whorl, without any remnant of upper palatal part of aperture attached to parietal wall in angular region. Dimensions and proportions of 3 adult specimens (type series): see Table 7. Remarks. Conchologically, differs from P. (M.) martensiana by wide axial ribs on teleoconch (width of ribs more than width of intercostal spaces) and from another two species of the subgenus by much larger size and less curved palatal edge of aperture. Etymology. From the Latin auris, meaning ear, and the local chimaoré language bole, meaning large; with reference to the overall appearance of the shell; used as a noun in apposition. DISCUSSION The status of Pseudelma madagascariensis Fischer-Piette, Blanc & Vukadinovic 1974 Fischer-Piette et al. (1974: 507) described Pseudelma madagascariensis based on two shells in the Dautzenberg collection ex coll. G. Petit, in the

24 146 A. Abdou, I. V. Muratov and P. Bouchet original description said to carry a label Elma, Madagascar. Fischer-Piette et al. had received this material on loan from Institut Royal des Sciences Naturelles de Belgique, Brussels. The loan was apparently never returned to Brussels, and the material could not be located in MNHN during the course of the present research. It may have been part of Madagascar material taken to Perpignan by F. Salvat for the preparation of Fischer-Piette et al. (1994), but it could not be located in Perpignan by B. Salvat (pers. com.). The shortly reflected columellar edge and the (partially because of that) widely open umbilical funnel suggest that the species belongs to Elma H. Adams 1866, rather than to Pseudelma. The original illustration of the holotype represents only a front view, which is inadequate for a final evaluation of the taxon, but we suggest that Pseudelma madagascariensis is a junior synonym of Elma messageri (Bavay & Dautzenberg 1904), or perhaps of Elma tonkiniana (Bavay & Dautzenberg 1904). This would imply that the type locality was erroneous and that Pseudelma madagascariensis originated from Vietnam. G. Petit did collect in Madagascar, but not in Vietnam (Fischer- Piette 1951: 20), and we do not want to speculate on how and when the error was made. Emberton (1994, 1999, 2001, 2002) did not record any species remotely resembling Elma or Pseudelma from Madagascar, except the reference to Pseudelma madagascariensis by Fischer-Piette et al. (1994) (Emberton 2003: 225). Relationships and zoogeography Despite the recent review by Schileyko (2000), the family Streptaxidae is in great need of revision at all taxonomical levels. Many genera are known by the shell only and their subfamily allocations are doubtful. Schileyko (2000) has classified Pseudelma in the subfamily Gibbinae (= Orthogibbinae). However, despite a superficial shell resemblance to some members of the Orthogibbinae (namely Edentulina, Gonospira Swainson 1840, and Plicadomus Swainson 1840), Pseudelma unequivocally belongs to the subfamily Enneinae (sensu Schileyko 2000) based on the absence of a penial sheath, the presence of penial caecum, the large talon and uniform, undifferentiated small hooks in the penis. Without knowledge of the anatomy of the SE Asian Elma, its relationship to Pseudelma is entirely speculative. The relationships of Pseudelma to Maurennea (type species Enna poutrini Germain 1918, from Mauritius) can be discussed on more solid ground. Both genera share with Ennea the presence of uniform, undifferentiated hooks in the penis and the absence of a penial sheath, thus Pseudelma and Maurennea would appear to be related to Ennea more than to any other streptaxid genus with known anatomy. Further, in his description of Maurennea, Schileyko (2000: 799) remarked that the genus occupies a somewhat isolated position because of presence of at least three unique characters: unusually large talon; very short free oviduct and vagina; also very short vas deferens. With the exception of Marielma (which cannot be said to have a very short vas deferens), Schileyko s statement applies as well to Pseudelma. Besides Mauritius, Schileyko also