Phaedusa shanica (Boettger & Ponsonby, 1888)

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

1 Phaedusa shanica (Boettger & Ponsonby, 1888)

Figs 3A , 4A, B , 5A-D , 6A , 19K

Clausilia (Pseudonenia) shanica Boettger & Ponsonby in Godwin-Austen 1888: 244. Type locality: "Shan Hills, near Pingoung, Burma, at a height of about 2500 feet" [Pinlaung Township, Shan State, Myanmar].

Clausilia [ Phaedusa (Pseudonenia) ] Phaedusa shanica - Gude 1914: 326, figs 111, 112.

Phaedusa (Phaedusa) shanica - Nordsieck 2002b: 88. Nordsieck 2007: 32.

Phaedusa shanica - Zilch 1954: 34, pl. 3, fig. 46. Nordsieck 1974: 46, fig. 6, pl. 2, fig. 6. Grego et al. 2021: 27. Szekeres et al. 2021a: 183-185, fig. 11a, b.

Material examined.

Limestone hills (Apache Cement Factory), Pyinyaung Village, Meiktila District, Mandalay Region, Myanmar (20°49'39.1"N, 96°23'35.1"E): CUMZ 13032 (6 shells Fig. 4A, B ), CUMZ 13033 (40 specimens in ethanol), JG-C2881 (2 shells) .

Description.

Shell fusiform, turreted, translucent, and pale yellowish brown; spire acute. Shell surface with thin and dense oblique striations; suture distinct. Whorls 11- 13½, little convex, regularly growing and attenuated to apex, last whorl somewhat compressed. Aperture obliquely rounded to pear-shaped, basis rounded and narrowing towards parietal sinus; peristome slightly protruded, thickened, and expanded. Superior lamella low, continuous with spiralis, and very low at transition to spiralis to almost separated. Inferior lamella spirally ascending, close to 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, three: first plica strong and longest; second plica very weak and close to first plica; third plica oblique from subcolumellaris and sometimes almost connected to second plica. Palatal plicae not visible without cracking shell. Clausilium plate lateral side, broad, rounded and slightly thickened at tip.

Genitalia (n = 5). Atrium (at) short; penis (p) muscular, cylindrical, and gradually narrower towards epiphallus. Epiphallus (ep) muscular, cylindrical, ca. same as penis length and size, and gradually widening to proximal end. Penial retractor muscle (pr) attached proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig. 5A ). Internal sculpture of penis smooth-surfaced and with 3 to 5 longitudinal folds (Fig. 5B ); at transition from penis to epiphallus with irregularly corrugated and wrinkled folds that randomly split and merge (Fig. 5C ). Internal sculpture of epiphallus with large papillae arranged in oblique rows (Fig. 5D ).

Vagina (v) slender at junction of atrium, then bulging at connection of free oviduct (fo) and distal part of pedunculus (dpb), and almost as long as free oviduct. Distal part of pedunculus large, long, and basally stouter; diverticulum (db) slender, nearly equal to dpb length; proximal part of pedunculus (ppb) large, long, measuring ~ 3/4 of diverticulum length, and bursa copulatrix (bb) ovoid (Fig. 5A ).

Radula. Each row contains ~ 47 teeth with half-row formula: central-(lateral)-marginal teeth (1-(11-12)-23). Central tooth symmetrically tricuspid; mesocone large with pointed tip; ectocones triangular and located near the base. Lateral teeth asymmetrically bicuspid with small and pointed ectocone located at base; endocone large with pointed tip. Marginal teeth with asymmetrical tricuspids starting at approximately tooth number 11 or 12; mesocone large with dull tip; endocone and ectocone with small and pointed tips. Marginal teeth gradually reduced in size and becoming multicuspid marginally (Fig. 6A ).

Distribution.

Phaedusa shanica is collected from probably nearby the type locality and likely restricted in Myanmar. It appears to be quite abundant in the limestone hills based on the high numbers collected in our samplings.

Remarks.

Phaedusa shanica is very similar to P. theobaldi (Blanford, 1872) in having two or three palatal plicae which tend to connect at the second and third plicae. Phaedusa theobaldi (Fig. 19M ) can be distinguished by its less turreted shell, coarser striations, darker horny color, superior lamella and spiralis separated, and not emerged subcolumellaris. These two species are difficult to distinguish at first sight; additional materials from the type locality and the genitalia of P. theobaldi , are required to elucidate the relationship between these two species.

Our specimens slightly differ from the type specimen in having three separated palatal plicae, or sometimes second and third plicae well developed and connected (Fig. 4B ). According to Nordsieck’s (1974: fig. 6) drawing, the lectotype SMF 62260 has only two almost connected first and second palatal plicae, while the probable paralectotype as stated in Gude (1914: fig. 112) has palatal plicae pattern similar to the specimens examined herein. Therefore, we assume that the distinct or indistinct second plica might be attributed to morphological variation. Shell variations among the examined materials for P. shanica were observed, including slender to regular fusiform shell, oblique to subquadrate aperture, and the third plica may be well developed and reach to the second plica (Fig. 4B ).

In addition, Phaedusa lypra (Mabille, 1887) from Shan State also resembles this species in shell form; however, P. lypra has a blunter spire, less turreted shell, and wider aperture sinus ( Szekeres et al. 2021a: fig. 10f). Phaedusa burmanica (Gude, 1914) and P. bocki menglunanensis (Luo, Cheng & Zhang, 1998) from Shan State differ from P. shanica in having a larger shell, five distinct palatal plicae that can be seen from outside of shell, wavier and coarser shell surface, and clausilium with a hook (Fig. 4 ). Regarding the genitalia, P. shanica possesses more simple and smooth longitudinal folds and reticulated papillae in the epiphallus, while P. burmanica has strongly wavy, irregularly dense, and crowded longitudinal folds along the epiphallus with a distinct fold near the vas deferens (Fig. 5 ).

Figures

Figure 3. Living snails A Phaedusa shanica from Pyinyaung Village, Mandalay Region (SH ~ 14 mm) B Oospira philippiana from Kayon Cave, Mon State (SH ~ 22 mm) C Oospira bulbus from Sanbel Cave, Mon State (SH ~ 19 mm) D Oospira ovata from Pathein Mountain, Mon State (SH ~ 16 mm) E Oospira gouldiana from Kaw Ka Thuang Cave, Kayin State (SH ~ 26 mm) F Oospira shanensis from Nanthe Cave, Shan State (SH ~ 25 mm).

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 5. Genital anatomy of A-D Phaedusa shanica, specimen CUMZ 13033 A whole reproductive system B internal sculpture of penis C transition from penis to epiphallus D internal sculpture of epiphallus and E-G Phaedusa burmanica, specimen CUMZ 13035 E whole reproductive system F overview internal sculpture of penis and epiphallus G internal sculpture of proximal epiphallus. Yellow arrows indicate approximate transitional position from penis to epiphallus.

Figure 6. Radula morphology A Phaedusa shanica, specimen CUMZ 13033 and B Phaedusa burmanica, specimen CUMZ 13035. Blue color indicates the central teeth row; yellow color indicates the transition from lateral to marginal teeth. ' C' indicates central tooth.

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).