4 Oospira philippiana (Pfeiffer, 1847)

Figs 2, 3B, 7A-C, 8A-C, 15A, 19H

Clausilia philippiana Pfeiffer, 1847: 69. Type locality: "Mergui in imperio Birmanorum" [near Myeik, Tanintharyi Region, Myanmar]. Küster 1850: 100, pl. 11, figs 7-9. Pfeiffer 1868: 409. Hanley and Theobald 1874: 48, pl. 118, fig. 10. Sowerby 1875: Clausilia pl. 4, species 35.

Clausilia (Phaedusa) philippiana -Adams and Adams 1855: 184. Pfeiffer 1856: 180. Martens 1860: 275. Stoliczka 1871: 174, pl. 6, figs 7-10.

Clausilia (Oospira) philippiana - Blanford 1872: 205, pl. 9, fig. 14. Nevill 1878: 182. Kobelt 1880: 289, pl. 86, fig. 29. Pfeiffer and Clessin 1881: 392. Tapparone-Canefri 1889: 329. Gude 1914: 333.

Clausilia [ Phaedusa (Oospira)] Phaedusa philippiana - Boettger 1878: 56.

Oospira (Oospira) philippiana - Nordsieck 2002b: 86. Nordsieck 2007: 24.

Oospira philippiana - Nordsieck 2021: 52, pl. 1, fig. 8. Szekeres et al. 2021a: 175, fig. 8c. Szekeres et al. 2021b: 45.

Material examined.

Possible syntype SMF 62294 / 1 ex. H. Dohrn collection from Burma: [Mergui] (Fig. 7A). Saddan Cave, ~ 600 m south of Kayon Cave, Mawlamyine Township, Mawlamyine District, Mon State, Myanmar (16°31'42.8"N, 97°43'2.1"E): CUMZ 13037 (10 adults + 5 juveniles, Fig. 7C). Kayon Cave [formerly called Farm Caves] ~ 10 km from Mawlamyine Township, Mawlamyine District, Mon State, Myanmar (16°32'0.5"N, 97°42'53.5"E): CUMZ 13038 (6 shells; Fig. 2), CUMZ 13039 (15 specimens in ethanol). Pha Boang Cave from Mawlamyine Township, Mawlamyine District, Mon State, Myanmar (16°17'14.04"N, 97°54'4.28"E): CUMZ 13040 (9 adults + 9 juveniles, Fig. 7B), CUMZ 13041 (15 specimens in ethanol) .

Description.

Shell ovate-fusiform, opaque, and chestnut-brown color; spire blunt. Shell surface nearly smooth or with very thin striations; suture distinct. Whorls 5- 6½, convex, regularly growing and bluntly attenuated to apex. Aperture obliquely pear-shaped, basis broader and narrowing towards parietal sinus; peristome detached, thickened, expanded and little reflexed. Superior lamella developed, continuous with spiralis, and low at transition to spiralis. Inferior lamella steeply ascending, distant from superior lamella and ending at peristome. Subcolumellaris emerged, and only visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, 7-9: first plica strong and longest; following plicae shorter, parallel, nearly equal in length, gradually reduced towards anterior. Clausilium plate lateral side, slightly broad and rounded at tip.

Genitalia (n = 5). Atrium (at) short and slender; penis (p) muscular and cylindrical. Epiphallus (ep) muscular, cylindrical, ca. same length and half of the diameter of penis and broadest at middle part. Penial retractor muscle (pr) attaches proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig. 8A). Internal sculpture of penis consists of two parts: region near atrium ~ 1/3 of penis length with series of irregular transverse folds, chevron-shaped; region near epiphallus becoming smooth surface and relatively thick with 5-7 longitudinal folds (Fig. 8B). Internal sculpture of epiphallus with elevated papillae arranged in oblique rows (Fig. 8C).

Vagina (v) thick and very short, ~ 1/3 of free oviduct (fo) length. Distal part of pedunculus (dpb) large and long; diverticulum (db) long, ~ 2 × length and slightly larger diameter than dpb; proximal part of pedunculus (ppb) slender, ca. equal in length to diverticulum, and bursa copulatrix (bb) with distinct ovate shape (Fig. 8A).

Radula. Each row contains ≥ 39 teeth with half-row formula: central-(lateral)-marginal teeth (1-(11-12)-19+). Central tooth unicuspid with rounded to blunt tip. Lateral teeth bicuspid: endocone large and rounded tip; ectocone very small, pointed tip and located near the base. Marginal teeth asymmetrically tricuspid starting at approximately tooth number 11 or 12: mesocone large and curved to blunt tip; endocone small and located near tip of mesocone; ectocone triangular, pointed tip and located near the base. Outermost teeth have been lost during the preparation process (Fig. 15A).

Distribution.

In Myanmar, this species is reported from Kayin, Mon and Tanintharyi (Gude 1914; Szekeres et al. 2021a, b). In addition, the records outside Myanmar are from Kanchanaburi Province, Thailand (Szekeres et al. 2021b), and further in Andaman Islands, but mentioned as dubious record (see Szekeres et al. 2021a: 177). In this survey, three populations were collected from isolated limestone karsts in Salween River Basin with relatively high abundance.

Remarks.

Oospira stoliczkana can be distinguished from O. philippiana by its elongate ovoid shell, pale color, and higher numbers of plicae. In terms of the genital organs, the male internal sculpture of O. philippiana has thicker and denser corrugated folds near the atrium than in O. stoliczkana (Fig. 10F). Moreover, O. vespa can be differentiated from this species by having an acute spire, aperture more oblique and broader, whorls more expanded.

Among the examined specimens, those from the Pha Boang Cave population (24 shells) have larger and darker shells with more widely spaced and up to nine developed palatal plicae. In contrast, specimens from the Kayon Cave (21 shells) and Saddan Cave (15 shells) populations are uniform in terms of a smaller shell and seven closer and weaker plicae (Table 1).

No specimens were found at the type locality ‘Mergui’ [Myeik]; but Szekeres et al. (2021b) reported material from Tanintharyi Region. Instead, multiple populations with high abundance were collected in the vicinity of Salween River Basin in this present study (Fig. 1; Table 1). This agreed with Stoliczka’s (1871: 175) statement that the species was 'common at the Farm-caves near Moulmein on limestone hills’ .