Paropeas walkeri ( Benson, 1863 )

Man, Nem Sian, Ablett, Jonathan D., Lwin, Ngwe, Sutcharit, Chirasak & Panha, Somsak, 2024, Contributions on a small collection of the former Subulinidae Fischer & Crosse, 1877 (Eupulmonata, Achatinoidea) with catalogue of the Glessula and Rishetia species recorded from Myanmar, ZooKeys 1208, pp. 173-239 : 173-239

26 Paropeas walkeri ( Benson, 1863)

Fig. 12 I – L , Table 1

Spiraxis walkeri Benson, 1863: 90. Type locality: ad Portum Blair [Port Blair, Andaman Islands, India]. Pfeiffer 1868: 189. Hanley and Theobald 1873: 34, pl. 79, fig. 4.

Opeas walkeri — Theobald 1870: 395. Godwin-Austen 1895: 443. Blanford 1903: 280.

Stenogyra (Opeas) walker i — Nevill 1878: 165.

Stenogyra [Spiraxis (Euspiraxis)] walkeri — Pfeiffer and Clessin 1881: 323.

Prosopeas walkeri — Pilsbry 1906: 29, 30, pl. 6, fig. 70. Gude 1914: 363, 364. Ramakrishna et al. 2010: 183. Preece et al. 2022: 130, 131, fig. 56 e.

Type specimens.

Syntypes UMZC I. 103115. A (5 shells; Fig. 12 I , after Preece et al. 2022: fig. 56 e) ex. R. McAndrew collection from Andaman Island.

Other material.

NHMUK 1885.2. 18.13–18 ex E. S. Berkeley collection Viper Id. Andamans: (6 shells; Fig. 12 J ). Aik Kham Cave, Taunggyi Township, Taunggyi District, Shan State, Myanmar (20 ° 49 ' 07.0 " N, 97 ° 13 ' 42.0 " E): CUMZ 13077 (3 shells; Fig. 12 K ). Ywangan Village, near Lin Way Monastery, Kalaw Township, Taunggyi District, Shan State, Myanmar (21 ° 13 ' 43.3 " N, 96 ° 33 ' 19.2 " E): CUMZ 13078 (2 shells; Fig. 12 L ).

Description.

Shell slender, conical, translucent, whitish to pale yellowish colour, and with 8–8 ½ whorls. Apex rounded; protoconch ~ 2 whorls, rounded and with fine radial striations on entire whorls. Spire high, gradually tapering, and turreted; whorls flatly convex and last three whorls nearly equal; suture narrow and deep. Aperture narrowly ovate and elongate; peristome thin; columella straight or slightly concave; columellar margin simple to slightly expanded. Umbilicus narrowly opened to closed.

Distribution.

This species was originally described from the Andaman Islands, India, and was later recorded in Shan State, Myanmar and Thailand ( Gude 1914; Panha 1998).

Remarks.

In Myanmar, Paropeas terebralis and P. walkeri are both recorded from Shan State. However, P. walkeri possesses broader, fewer, and more convex whorls, a straight columella with a slightly reflected columellar margin, weaker radial striations, shallow suture, and embryonic whorls rounded. By contrast, P. terebralis has slimmer, higher, and flatter whorls, more concave columella, strong radial striations, deeper suture, and more pointed embryonic whorls. Additionally, P. walkeri also differs from P. turricula by its more convex whorls, straight columella, slightly reflected columellar margin, finer and crowded radial striations, deeper suture, and embryonic whorls rounded with stronger radial striations. Furthermore, P. walkeri can be differentiated from P. swettenhami by its slenderer shell, convex and closely grow whorls, deeper suture, more rounded protoconch whorls, distinctly turreted spire, and straight columella. Prosopeas swettenhami displays a broader shell, flatter whorls, shallow suture, convex protoconch whorls, less turreted spire, and more concave columella.

Among the specimens examined from Shan State, we observed shell variations, such as the columellar margin being either expanded or not expanded and the columella being straight or slightly concave. In addition, the specimen identified as P. walkeri from the Andaman Islands (Fig. 12 J ) exhibits a broader shell and a more expanded columellar margin compared to the syntype specimen (Fig. 12 I ).

Figures

Figure 12. A – C Opeas filiforme A lectotype SMF 227532 from Gulf von Siam: Samui-Inseln B, C specimen CUMZ 13074 from Tanintharyi Region, Myanmar D Paropeas swettenhami, syntype MNHN - IM- 2000-38930 from Malacca E Paropeas tchehelense, syntype MNHN - IM- 2000-38932 from Pérak, Mont Tchéhèl F Paropeas terebralis, syntype NHMUK 1888.12. 4.1081 from Shan States, Burma G, H Paropeas turricula G syntypes NHMUK 1859.8. 1.10 from Siam and H specimen CUMZ 13076 from Tanintharyi Region, Myanmar I – L Paropeas walkeri I syntypes UMZC I. 103115. A from Andaman Island (after Preece et al. 2022: fig. 56 e) J specimen NHMUK 1885.2. 18.13–18 from Viper Id. Andamans K specimen CUMZ 13077 from Taunggyi Township, Shan State, Myanmar with embryonic whorls and aperture and L specimen CUMZ 13078 from Kalaw Township, Shan State, Myanmar with embryonic whorls and aperture. Photographs: V Gojšina & B Páll-Gergely (A), P Bourguignon (D, E).