Phaedusa burmanica (Gude, 1914)

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

2 Phaedusa burmanica (Gude, 1914)

Figs 4C, D , 5E-G , 6B , 18F

Clausilia [ Phaedusa (Euphaedusa) ] Phaedusa burmanica Gude, 1914: 311, fig. 106. Type locality: "Burma, Tonghu" [Taungoo District, Bago Region, Myanmar].

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

Phaedusa burmanica - Nordsieck 1974: 46, fig. 5, pl. 2, figs 3, 4. Grego et al. 2021: 27. Szekeres et al. 2021a: 181, fig. 10a.

Material examined.

Myin Ma Hti Cave , Kalaw City, Shan State, Myanmar (20°35'26.1"N, 96°36'42.6"E): CUMZ 13034 (2 shells + 1 incomplete shell; Fig. 4C, D ), CUMZ 13035 (1 specimen in ethanol) .

Description.

Shell fusiform, turreted, translucent, and pale chestnut-brown; spire acute. Shell surface glossy with thin and dense striations; suture distinct. Whorls 12-13, little convex, regularly growing and attenuated to apex; last whorl compressed. Aperture vertically subquadrate, 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. Inferior lamella spirally ascending, close to superior lamella and ending at peristome. Subcolumellaris emerged, and visible in oblique view. Principalis running along lateral-dorsal side and anterior end visible through oblique apertural view. Palatal plicae lateral, distinctly five: first plica strong, longest, and nearly connected to principalis anteriorly; second and fifth plicae almost equal and slightly strong; third and fourth plicae weakest and almost not visible. Palatal plicae visible through translucent shell. Clausilium plate lateral side, broad, rounded and with hook.

Genitalia (n = 1). Atrium (at) short and slender; penis (p) muscular, cylindrical, broadest at middle part and gradually narrower towards epiphallus. Epiphallus (ep) muscular, cylindrical, ca. same length and size as penis, gradually enlarging to proximal end. Penial retractor muscle (pr) attached proximally to epiphallus. Vas deferens (vd) slender, and shortly bounded at atrium and penis junction (Fig. 5E ). Internal sculpture of penis smooth-surfaced and slightly wavy with ca. four longitudinal folds (Fig. 5F ). Internal sculpture of epiphallus generally defined as two parts: region near penis with wavy longitudinal folds, then gradually becoming more densely crowded towards proximal epiphallus; region near vas deferens with strong folds and papillae arranged in oblique rows (Fig. 5G ).

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, basally stouter, and broadest near entrance of diverticulum; diverticulum (db) large, as long as dpb; proximal part of pedunculus (ppb) large, measuring ~ 1/2 diverticulum length, and bursa copulatrix (bb) ovoid (Fig. 5E ).

Radula. Each row contains ~ 51 teeth with half-row formula: central-(lateral)-marginal teeth (1-(13-14)-25). Central tooth small, symmetrically tricuspid; mesocone large with dull tip; ectocones very small. Lateral teeth asymmetrically bicuspid: endocone large and with dull tip; ectocone very small, pointed tip and located near the base. Marginal teeth tricuspid starting at approximately tooth number 13 or 14; mesocone long and dull tip; endocone very small and located near tip of mesocone; ectocone small with pointed tip. Marginal teeth gradually becoming polycuspid towards radula margin (Fig. 6B ).

Distribution.

Apart from the type locality, this species is widely known from Bhamo, Kachin State ( Gude 1914) to Shan State and the Mandalay Region in Myanmar ( Grego et al. 2021).

Remarks.

Phaedusa bocki menglunanensis from Shan State can be distinguished from this species by its inferior lamella less spirally ascending, palatal plicae longer, obliquely arranged and more spaced between them, shell surface finer and more curved striations, aperture vertically quadrate, and subcolumellaris distinctly visible in frontal view. Phaedusa bocki thompsoni Grego & Szekeres, 2021 also differs from this species in having a more vertical aperture, acute spire, and palatal plicae more on dorsal side (see Szekeres et al. 2021a: fig. 9f).

Variation was observed among the examined specimens in having the superior lamella and spiralis either separated or connected.

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 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 18. Synoptic view of the clausiliid species recorded from Myanmar A Indonenia admirabilis, holotype NHMUK 20200185 B Oospira andersoniana, specimen CUMZ 13054 C Oospira arakana, lectotype NHMUK 1888.12.4.1037 D Cylindrophaedusa bacillum, specimen NHMUK 1906.2.2.345 E Oospira bulbus, possible syntype NHMUK 1903.7.1.1278 F Phaedusa burmanica, holotype NHMUK 1888.12.4.1058 G Oospira decollata, paratype ZISP H Indonenia excellens, specimen NHMUK 20200189 I Oospira fusiformis, holotype NHMUK 1906.2.2.380 J Oospira gouldiana, lectotype NHMUK 196548 K Oospira gracilior, lectotype NHMUK 1907.12.30.243 L Oospira insignis, lectotype USNM 117120 M Phaedusa kazueae, holotype NHMUK 20200187 N Phaedusa lemani (after Gude, 1914: fig. 107) O Oospira limborgi, holotype NHMUK 1903.7.1.1266, and P Oospira luneainopsis sp. nov., holotype CUMZ 13062.