Amphidromus buelowi Fruhstorfer, 1905

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

publication ID	https://dx.doi.org/10.3897/zookeys.1196.112146
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scientific name	Amphidromus buelowi Fruhstorfer, 1905
status

Treatment

Amphidromus buelowi Fruhstorfer, 1905 View in CoL

Figs 6H, I View Figure 6 , 12B View Figure 12 , 14D-F View Figure 14 , 15 View Figure 15 , 16 View Figure 16

Amphidromus Amphidromus ( Goniodromus ) bülowi Fruhstorfer, 1905: 83-84, pl. 1, fig. 2. Type locality: West-Sumatra. Rolle 1908: 67. Laidlaw and Solem 1961: 587, 606, fig. 37.

Amphidromus buelowi Amphidromus buelowi . Dautzenberg and Fischer 1906: 365-366, pl. 8, figs 10-12. Degner 1928: 360. Benthem Jutting 1959: 165.

Amphidromus Amphidromus (Goniodromus) asper Haas, 1934: 96, figs 11, 12. Type locality: Süd-Annam, 120 km von der Küste, auf dem Wege zum Plateau von Lang-Bian, zw. 600-1000 m [South Annam, 120 km from the coast, on the way to the plateau of Lang-Bian, between 600-1000 m]. Laidlaw and Solem 1961: 588, 601. Zilch 1953: 138, pl. 25, fig. 44. syn. nov.

Amphidromus asper . Schileyko 2011: 49. Páll-Gergely et al. 2020: 49, 51, fig. 15. Thach 2020a: pl. 76, fig. 893 right.

Amphidromus bulowi [sic]. Huber 2015: figs 9, 10. Sutcharit et al. 2015: 61, fig. 4e.

Amphidromus Amphidromus (Goniodromus) bulowi bulowi [sic]. Parsons and Abbas 2016: 240-242, figs 4 bottom, 5, 6a, b, d, 7.

Amphidromus franzhuberi Thach, 2016: 64-65, fig. 42; pl. 23, figs 315-319. Type locality: along the border of Nha Trang outskirts and Khanh Vinh District, Khanh Hoa Province (Central Vietnam). Páll-Gergely et al. 2020: 50, fig. 14. Thach 2020a: 58, pl. 76, fig. 893 left. Thach 2021: 60 syn. nov.

Amphidromus buelowi . Páll-Gergely et al. 2020: fig. 16.

Material examined.

Indonesia: Sinistral , lectotype of " Amphidromus buelowi ", NHMUK 1910.12.30.98 (Fig. 15A View Figure 15 ) . Vietnam: Dextral , holotype of " Amphidromus asper ", SMF 7762 (Fig. 15B View Figure 15 ). Dextral, holotype of " Amphidromus franzhuberi ", MNHN-IM-2000-31892 (Fig. 15C View Figure 15 ) .

Other material examined.

Indonesia: 2D specimens, Padang Sökeli, Singalang, RBINS I.G. 10591/1-2 (Fig. 15D View Figure 15 ); 4D specimens, Mount Singgalang, Sepuluh Koto, Tanah Datar Regency, West Sumatra, NMNS-8764-022- NMNS-8764-025 (Fig. 15E View Figure 15 ).

Vietnam: 2D specimens, Lang-Biang, Annam, RBINS I.G. 10591/3-4 (Fig. 15F View Figure 15 ); 2D specimens, Lang-Biang plateau, Lac Duong District, Lam Dong Province, NMNS-8764-026, NMNS-8764-027 (Fig. 15G View Figure 15 ); 6D + 1S specimens, Nha Trang, Khanh Hoa Province, NMNS-8764-028- NMNS-8764-034 (Fig. 15H, I View Figure 15 ).

Diagnosis.

Shell large and chirally dimorphic. Shell colour with irregularly zigzag of dark radial streaks, and dark triangular blotches. Aperture elliptical ovate with more or less prominent anterior notch and umbilical hump; twisted columella plait. Genitalia with appendix.

Differential diagnosis.

Amphidromus buelowi differs from the similar species A. asperoides sp. nov. in having a distinct twisted columella plait, a prominent umbilical hump encircling columellar area, and an apertural notch projecting anteriorly. In contrast, A. asperoides sp. nov. possesses a straight columella, and without apertural notch and umbilical hump. In addition, on the soft body of living snail, the entire body of A. buelowi is reddish orange, while A. asperoides sp. nov. exhibits a uniform brownish yellow to pale brown body. Amphidromus buelowi is also recognised by a distinct clade in the molecular phylogeny (Fig. 2 View Figure 2 ), with the closest p -distance to A. ingens in COI (12.23%) and A. asperoides sp. nov. and A. ingens in 16S (4.61%) (Table 2 View Table 2 ).

Description.

Shell large (height 45.3-51.1 mm, width 26.2-26.6 mm), chirally dimorphic, solid, and ovate conical. Spire conical with white or pale colour; apex acute without black spot on tip. Whorls 6-7 little convex to smooth; suture wide and shallow; last whorl well rounded to slightly elongated and with more or less prominent umbilical hump. Periostracum thin corneous; varices generally present. Shell ground colour pale yellowish, decorated with irregular zigzag of dark radial streaks, and dark triangular blotches connected with dark streaks. Parietal callus thickened, white and much thinner in central area. Aperture elliptical ovate; with more or less anterior notch; inner side of outer wall whitish colour; peristome thickened, expanded, and reflexed but not attached to last whorl; lip whitish. Columella white, straight and with distinct twisted plait. Umbilicus imperforate.

Radula. Teeth arranged in anteriorly pointed V-shaped rows. Central tooth monocuspid and slightly elongate-spatulate teeth with truncated cusp. Lateral teeth bicuspid; endocone curved with wide notch and blunt cusp; ectocone large with truncated cusp. Lateral teeth gradually transformed to asymmetric tricuspid marginal teeth. Outermost teeth with small and curved cusp on ectocone, and endocone and mesocone with curved cusps (Fig. 12B View Figure 12 ).

Genital organs. Atrium relatively short. Penis slender, conical, and nearly as long as vagina. Penial retractor muscle inserting on epiphallus close to penis. Epiphallus long, slender tube, and almost same diameter as penis. Flagellum short, extending from epiphallus and terminating in slightly enlarged folded coil. Appendix short, thin tube, 3 × longer than flagellum, and approximately as long as epiphallus. Vas deferens slender tube passing from free oviduct and terminating at epiphallus-flagellum junction (Fig. 14D View Figure 14 ). Internal wall of penis corrugated, exhibiting series of thickened and swollen longitudinal penial pilasters forming fringe around penial wall, and with weaker folds around base of penial verge. Penial verge short conical with nearly smooth surface (Fig. 14E View Figure 14 ).

Vagina slender, long cylindrical, and ~ 2 × longer than penis. Gametolytic duct enlarged cylindrical tube then abruptly tapering to long, slender tube terminally, connected to elongate gametolytic sac. Free oviduct short; oviduct compact, enlarged to form lobule alveoli (Fig. 14D View Figure 14 ). Internal wall of vagina possessing corrugated ridges near genital orifice; ridges becoming thinner and smooth longitudinal vaginal pilasters in middle, swollen with irregularly shaped deep crenelations close to free oviduct opening (Fig. 14F View Figure 14 ).

Living specimens with soft body morphology generally similar to A. ingens . Animals with reddish orange body covered with reticulated skin. Lateral of body vary from yellowish (in younger specimen) to dark reddish orange colour (older specimens). Foot broad and long with reddish orange colour near foot sole margin. Head and dorsal of anterior body with reddish orange to dark colour. Upper tentacles pale reddish orange to brownish; lower tentacles short and paler in colour (Fig. 6H, I View Figure 6 ).

Haplotype network.

There was a total of four COI haplotypes (Fig. 16A View Figure 16 ) and three 16S haplotypes (Fig. 16B View Figure 16 ) of A. buelowi in this study, and the highest numbers of mutational steps in the COI and 16S minimum spanning networks are ten and one, respectively.

Distribution.

The species has a widely disjunct distribution: one in Mount Singgalang, West Sumatra, Indonesia, and some localities in Khanh Hoa and Lam Dong provinces, South Vietnam.

Remarks.

This species was originally described by Fruhstorfer (1905) from four chirally dimorphic specimens from West Sumatra. Fruhstorfer (1905) also indicated that there was a similar species collected on the way to the Lang-Bian plateau, ~ 120 km inland from the coast in southern Vietnam. He sent one specimen from this locality to O.F. von Möllendorff, who did not describe or taxonomically treat this specimen any further. Later, Haas (1934), recognising that there were some differences in shell characters to A. buelowi , described this particular specimen (now deposited in SMF) as a new species, A. asper . Thach (2016) also described a similar species, A. franzhuberi from the border of Nha Trang, Vietnam, which is described to differ from A. buelowi in having a broader shell shape, more swollen body whorls, a less excavated base, a more inflated spire, a rounded anterior end of the outer lip, and monomorphic dextrality (just from four type series). However, Thach (2016) did not compare with A. asper from the nearby area. In this study, the samples from Nha Trang exhibit dimorphic chirality (the specimen lot containing both sinistral and dextral shell coiling; Fig. 15H, I View Figure 15 ), and upon examining the type specimens of A. asper and A. franzhuberi , they agree well with the type specimen of A. buelowi in having the common diagnostic traits of a distinct twisted columella plait, a prominent umbilical hump, and a distinct apertural notch. The molecular phylogeny also revealed that all specimens from Mount Singgalang, West Sumatra, Indonesia, and Lang-Biang plateau and Nha Trang, Vietnam belong to the same clade. The mutational steps between Indonesian and Vietnamese specimens are only ten and one in the COI and 16S haplotype networks, respectively (Fig. 16 View Figure 16 ). Based on the phylogenetic analyses and the common morphological diagnostics, we therefore treat A. asper and A. franzhuberi as junior subjective synonyms of A. buelowi .

Bülow (1905) introduced the monotypic subgenus Amphidromus Goniodromus to include A. buelowi , based on a less ovate aperture with an apertural notch projecting anteriorly. Later, Laidlaw and Solem (1961), although with doubt, listed Goniodromus as one of the three subgenera of Amphidromus , and included two more species, A. asper and A. mirandus Bavay & Dautzenberg, 1912. Another species, A. thachi , also possesses an aperture with prominent anterior notch (Fig. 17 View Figure 17 ). However, these three species, A. buelowi (and its synonyms A. asper and A. franzhuberi ), A. thachi , and A. mirandus did not together form a clade (Fig. 2 View Figure 2 ; C-TL, unpublished data), revealing that an apertural anterior notch is not a shared derived character. Thus, the subgenus Amphidromus Goniodromus is regarded herein as a junior subjective synonym of the subgenus Amphidromus Amphidromus .