Amphidromus haematostoma Moellendorff , 1898

Jirapatrasilp, Parin, Huang, Chih-Wei, Sutcharit, Chirasak & Lee, Chi-Tse, 2024, The arboreal snail genus Amphidromus Albers, 1850 (Eupulmonata, Camaenidae) of Southeast Asia: 1. Molecular systematics of some Vietnamese species and related species from Cambodia, Indonesia, and Laos, ZooKeys 1196, pp. 15-78 : 15

Amphidromus haematostoma Moellendorff, 1898

Figs 24A-G , 25A, B , 26

Amphidromus haematostoma Möllendorff, 1898: 74-75. Type locality: Boloven [Boloven Plateau, Champasak, Laos]. Pilsbry 1900: 182-183. Möllendorff 1901: 50. Pilsbry 1901: 169. Fischer and Dautzenberg 1904: 406. Richardson 1985: 19. Schileyko 2011: 51. Inkhavilay et al. 2019: 91, figs 43f, 44a-c.

Amphidromus haematostoma var. viridis Möllendorff, 1898: 75. Type locality: Boloven. Pilsbry 1900: 183. Fischer and Dautzenberg 1904: 406.

Amphidromus haematostoma var. varians Möllendorff, 1898: 75. Type locality: Boloven. Pilsbry 1900: 183. Fischer and Dautzenberg 1904: 406.

Amphidromus Amphidromus (Syndromus) haematostoma . Zilch 1953: 132, pl. 22, figs 4, 5. Inkhavilay et al. 2017: 34-35, figs 13o-r.

Amphidromus haematostomus [sic]. Laidlaw and Solem 1961: 527, 625.

Amphidromus haematostomus [sic] Amphidromus varians . Laidlaw and Solem 1961: 668.

Amphidromus haematostomus [sic] Amphidromus viridis . Laidlaw and Solem 1961: 670.

Amphidromus haematostoma varians . Richardson 1985: 19.

Amphidromus haematostoma viridis . Richardson 1985: 19.

Amphidromus Amphidromus (Syndromus) haematostomus [sic]. Lehmann and Maassen 2004: 20.

Amphidromus attapeuensis Thach & Huber in Thach, 2017: 37-38, figs 573-578. Type locality: Attapeu Province, southeast of Laos, close to Vietnam border. Thach 2020a: 51, 52. Thach 2021: 55.

Material examined.

Laos: Sinistral , lectotype of " Amphidromus haematostoma var. viridis ", SMF 7559/1 (Fig. 24A ); sinistral, lectotype of " Amphidromus haematostoma var. varians ", SMF 7561/1 (Fig. 24B ); sinistral, holotype of " Amphidromus attapeuensis ", NHMUK 20170278 (Fig. 24C ) .

Other material examined.

Laos: 5S specimens, Xe Pian village, Paksong District, Champasak Province, CUMZ 10217 (Inkhavilay et al. 2019: fig. 44a); two lots in W.J.M. Maassen Collection (8S specimens and 14S specimens), Boloven Plateau, Paksong District , Champasak; 4S specimens, Samphanh District , Phongsali Province, NMNS-8764-053- NMNS-8764-056 (Fig. 24D ); 20S specimens, Ba Chien, Pakse District , Champasak Province, NMNS-8764-057- NMNS-8764-076 (Fig. 24E, F ) .

Vietnam: 5S specimens, Kbang District, Gia Lai Province, NMNS-8764-077NMNS-8764-081 (Fig. 24G ).

Diagnosis.

Shell medium and sinistral. Parietal callus, lip and columella with bright to dark rose-pink. Varix sometimes present. Genitalia without appendix.

Differential diagnosis.

Amphidromus haematostoma differs from the similar sinistral species A. madelineae in having a whitish apex, slightly thickened parietal callus with pale to dark rose-pink colouration, while A. madelineae has tinted pink ~ 1-2 whorls from apex, and thin transparent parietal callus. This species also differs from the similar A. roseolabiatus in that the latter has a chirally dimorphic shell, a whitish apex and the genitalia with a very long appendix. The molecular phylogeny in this study reveals that A. haematostoma is a distinct clade from its sister A. madelineae (Fig. 2 ). The COI and 16S p -distances between A. haematostoma and A. madelineae are 13.93% and 6.04%, respectively (Table 2 ).

Description.

Shell medium (height 23.8-35.4 mm, width 13.3-21.0 mm), sinistral, ovate conical, rather thin and glossy. Spire elongate conical; apex acute, without black spot on tip, and earlier whorls whitish. Whorls 6-7 convex to smooth; suture wide and depressed; last whorl well rounded. Periostracum thick corneous or with green to greenish yellow colour; varix occasionally present. Shell ground colour white or yellowish colour (without periostracum); dark yellow subsutural band and a band at around umbilicus usually present (rarely indistinguishable). Parietal callus thickened with bright to dark rose-pink colour. Aperture broadly ovate and inner side of outer wall whitish; peristome little thickened, expanded, and weakly reflexed but not attached to last whorl; lip bright to dark rose-pink colour and with little darker colour at the edge. Columella bright to dark rose-pink colour, straight, or little twisted. Umbilicus imperforate.

Genital organs. Atrium relatively short. Penis slender, conical, and short ~ 1/3 of vaginal length. Penial retractor muscle thickened, long and inserting on epiphallus close to penis. Epiphallus stout tube and approximately as long as vagina. Flagellum short, extending from epiphallus and terminating in curved tip; appendix absent. Vas deferens slender tube passing from free oviduct and terminating at epiphallus-flagellum junction (Fig. 25A ). Internal wall of penis corrugated, exhibiting prominent series of thickened and swollen longitudinal penial pilasters forming fringe around penial wall, and with fine and weak folds around base of penial verge. Penial verge very short, with smooth surface, and opening at the tip (Fig. 25B ).

Vagina slender, long cylindrical, and ~ 2 × longer than penis. Gametolytic duct cylindrical tube then gradually tapering to slender tube terminally and connected to gametolytic sac (missing during dissection). Free oviduct short; oviduct compact, forming lobule alveoli (Fig. 25A ). Internal wall of vagina possessing corrugated ridges near genital orifice; ridges becoming smooth longitudinal vaginal pilasters in middle, swollen with irregularly shaped deep crenelations close to free oviduct opening (Fig. 25B ).

Distribution.

This species has a wide distribution range covering Attapeu, Champasak, and Phongsali provinces, Laos, and Gia Lai Province, Vietnam.

Remarks.

A degree of shell colour variation occurs in the specimens from Pakse, Champasak, Laos (Fig. 24E, F ) in having yellowish to golden-yellow periostracum, indistinct subsutural band and a dark rose-pink apertural lip. In addition, the type specimens and recently collected specimens from Kbang, Gia Lai, Vietnam (Fig. 24B, C, G ) tend to have broad brownish radial bands on the earlier spire whorls.

This species also exhibits a prominent population genetic structure, where some clades constitute only the specimens from the same collecting locality (Fig. 26 ). The COI intraspecific distance among all A. haematostoma specimens is 10.03%, which is the highest distance of all Amphidromus species in this study. This value is higher than twice the optimum intra/interspecific threshold value of 4% for stylommatophoran land snails ( Davison et al. 2009). However, as all specimens have congruent morphology as stated above, we refrain from treating each pool of samples from the same collecting locality as a distinct taxon, before more specimens from each locality are critically examined.

Figures

Figure 2. Bayesian phylogeny of Amphidromus spp. based on mitochondrial COI and 16 S genes. Nodal support values are given as SH-aLRT / aBayes / ultra-fast bootstrap (IQ-TREE, ML) / posterior probability (MrBayes, BI). An asterisk on each branch indicates a clade with all well-supported values (SH-aLRT ≥ 80 %, aBayes ≥ 0.95, BS ≥ 95 %, PP ≥ 0.95). Species numbers correspond to those in Fig. 1 and Tables 1, 2.

Figure 24. Shells of Amphidromus spp A-G Amphidromus haematostoma Moellendorff, 1898 A Lectotype of " Amphidromus haematostoma var. viridis " (SMF 7559) B lectotype of " Amphidromus haematostoma var. varians " (SMF 7561) C holotype of " Amphidromus attapeuensis " (NHMUK 20170278) D specimen from Samphanh, Phongsali, Laos (NMNS- 8764 - 056) E, F specimens from Ba Chien, Pakse, Champasak, Laos (NMNS- 8764 - 064, NMNS- 8764 - 076) G specimen from Kbang, Gia Lai, Vietnam (NMNS- 8764 - 080) H-M Amphidromus madelineae Thach, 2020 H holotype of " Amphidromus madelineae " (MNHN-IM- 2000 - 35566) I, J Specimens from Duy Xuyen, Quang Nam, Vietnam (NMNS- 8764 - 112, NMNS- 8764 - 108) K-M specimens from Za Hung, Dong Giang, Quang Nam, Vietnam (NMNS- 8764 - 114, NMNS- 8764 - 118, NMNS- 8764 - 122).

Figure 25. Genitalia of Amphidromus spp A, B Amphidromus haematostoma Moellendorff, 1898 from Ba Chien, Pakse, Champasak, Laos (NMNS- 8764 - 061), showing A general view of genitalia B interior structures of penis and vagina chamber C, D Amphidromus madelineae Thach, 2020 from Duy Xuyen, Quang Nam, Vietnam (NMNS- 8764 - 110), showing C general view of genitalia D interior structures of penis and vagina chamber. Red dots indicate the shape of the missing gametolytic sac. Green arrows indicate the genital openings. Abbreviations: e, epiphallus; fl, flagellum; fo, free oviduct; gd, gametolytic duct; gs, gametolytic sac; ov, oviduct; p, penis; pp, penial pilaster; pr, penial retractor muscle; pv, penial verge; v, vagina; vd, vas deferens; vp, vaginal pilaster.

Figure 26. Bayesian phylogeny of Amphidromus haematostoma Moellendorff, 1898 and Amphidromus madelineae Thach, 2020 based on mitochondrial COI and 16 S genes. Nodal support values are given as SH-aLRT / aBayes / ultra-fast bootstrap (IQ-TREE, ML) / posterior probability (MrBayes, BI). An asterisk on each branch indicates a clade with all well-supported values (SH-aLRT ≥ 80 %, aBayes ≥ 0.95, BS ≥ 95 %, PP ≥ 0.95).