Phaedusa bocki menglunanensis (Luo, Chen & Zhang, 1998)

Man, Nem Sian, Lwin, Ngwe, Sutcharit, Chirasak & Panha, Somsak, 2023, Further notes on the taxonomy of the land snail family Clausiliidae Gray, 1855 (Stylommatophora, Helicina) from Myanmar with description of two new species, ZooKeys 1160, pp. 1-59 : 1

3 Phaedusa bocki menglunanensis (Luo, Chen & Zhang, 1998)

Figs 4E, F , 19E

Hemiphaedusa menglunanensis Luo et al., 1998: 34, fig. 2. Type locality: Menglun, Mengla County, Xishuangbanna Prefecture, Yunnan Province, China. Chen and Zhang 1999: 162, pl. 5, fig. 1a, b. Chen et al. 2016: 111, fig. 2-52a.

Phaedusa (Phaedusa) bocki menglunanensis - Nordsieck 2007: 32.

Phaedusa bocki menglunanensis - Szekeres et al. 2021a: 180, 181, fig. 9e. Szekeres et al. 2021b: 46.

Material examined.

Aik Kham Cave , Taunggyi City, Shan State, Myanmar (20°49'7.0"N, 97°13'42.0"E): CUMZ 13036 (3 incomplete shells, Fig. 4E, F ) .

Description.

Shell fusiform, translucent, and pale yellowish brown; spire regularly acute. Shell surface with fine and coarse striations; suture wide and distinct. Whorls 12 and 13 nearly flattened, regularly increasing, and attenuated to apex. Aperture vertically subquadrate, basis rounded and narrowing towards parietal sinus; peristome protruded, expanded and little reflexed. Superior lamella low, continuous with spiralis, and low at transition to spiralis. Inferior lamella spirally ascending, slightly horizontal before reaching peristome and close to superior lamella. Subcolumellaris emerged, ending at peristome margin, and clearly visible in frontal view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, four or five: first plica distinct, longest, and nearly connected to principalis anteriorly; second plica ~ 1/2 of first plica length and remaining plicae oblique, equally spaced, and shorter. Palatal plicae visible through translucent shell. Clausilium plate lateral side, broad, rounded, and with hook.

Distribution.

Phaedusa bocki menglunanensis was originally described from Yunnan Province, China, which is near the borders with Vietnam and Laos. It was recently found in Shan State, along the Mekong River near the border with Laos ( Szekeres et al. 2021a).

Remarks.

No preserved specimens were found for examination of the genitalia. This subspecies and samples of P. bocki thompsoni collected from the same geographical range have a similar shell morphology, but P. bocki thompsoni has invisible subcolumellaris in frontal view, blunter and turreted spire, and whorls after antepenultimate whorl rapidly attenuated (see Szekeres et al. 2021a: fig. 9f). However, the holotype of P. bocki thompsoni from Thailand possesses a subcolumellaris that is visible in frontal view, and four to seven plicae that become shorter and somewhat diffuse towards the base ( Szekeres et al. 2021b: fig. 2d). More materials are required for comparison to determine whether the differentiating characters are consistently distinct between these two subspecies.

Figures

Figure 4. Shell and clausilial apparatus of A, B Phaedusa shanica, specimen CUMZ 13032 from Pyinyaung Village, Mandalay Region A shell B clausilial apparatus C, D Phaedusa burmanica, specimen CUMZ 13034 from Myin Ma Hti Cave, Shan State C shell D clausilial apparatus and E, F Phaedusa bocki menglunanensis, specimen CUMZ 13036 from Aik Kham Cave, Shan State E shell F clausilial apparatus. White arrows indicate principalis and yellow arrows indicate clausilium hook.

Figure 19. Synoptic view of the clausiliid species recorded from Myanmar A Phaedusa lypra, syntype MNHN-IM- 2000 - 2502 - 7 B Oospira magna, lectotype NHMUK 1901.3.17.156 C Oospira malaisei, holotype SMNH 3014 D Indonenia masoni, lectotype NHMUK 1888.12.4.1034 E Phaedusa bocki menglunanensis, specimen NHMUK 1903.7.1.3652 F Oospira mongmitensis, holotype UF 117571 (after Szekeres et al. 2021 b: fig. 1 d) G Oospira ovata, lectotype NHMUK 1906.2.2.378 H Oospira philippiana, possible syntype SMF 62294 / 1 I Oospira sardicola, holotype UF 117570 (after Szekeres et al. 2021 b: fig. 2 c) J Oospira shanensis, holotype NHMUK 1903.7.1.3544 K Phaedusa shanica, lectotype SMF 62260 L Oospira stoliczkana, holotype NHMUK 1888.12.4.1031 M Phaedusa theobaldi, lectotype NHMUK 1888.12.4.1056 N Phaedusa bocki thompsoni, specimen NHMUK 1903.7.1.1163 O Indonenia tuba, lectotype NHMUK 1907.12.30.241 P Oospira vespa, paralectotype MCZ 169456 and Q Oospira zediopsis sp. nov., holotype CUMZ 13064. Photo: P. Maestrati, MNHN (A), A Persson, SMNH (C).