Worthenia cf. pagoda Mansuy, 1912

Ketwetsuriya, Chatchalerm, Karapunar, Baran, Charoentitirat, Thasinee & Nützel, Al- Exander, 2020, Middle Permian (Roadian) gastropods from the Khao Khad Formation, Central Thailand: Implications for palaeogeography of the Indochina Terrane, Zootaxa 4766 (1), pp. 1-47 : 19-20

Worthenia cf. pagoda Mansuy, 1912

( Fig. 14 J–N)

cf. Worthenia pagoda Mansuy, 1912: 39 , pl. 7, fig. 6; Delpey, 1941: 353, fig. 26.

Material. Two specimens: ESKU-19- LP 17, 66.

Dimensions (mm): ESKU-19- LP 17: height = c. 6.6; width = 4.9. ESKU-19- LP 66: height = 5.5; width = c. 5.0; apical angle = 75º.

Description. Shell moderately high-spired, trochiform, consisting of 6 whorls; first three teleoconch whorls smooth, convex, rounded; mid angulation develops starting from the 4th whorl onward; the last quarter of the last whorl slightly deflected; suture slightly impressed; subsutural ramp with faint subsutural convexity, slightly concave on remaining part; ramp inclining at an angle of about 45–60°; subsutural ramp ornamented with three spiral ribs starting from 4th whorl and almost straight prosocline growth lines; spiral ribs ornamented with equally spaced nodes; mid-angulation forms periphery where selenizone situated; selenizone prominent, wide, comprising about 1/7 of the whole whorl face of 5th whorl, ornamented with equally spaced strong nodes, bordered by fine spiral ribs; lower whorl face facing abapically, concave, ornamented with two nodular spiral ribs; lowest spiral rib stronger, situated at angulation, forming basal edge; base convex, ornamented by several evenly spaced nodular spiral ribs, narrowly phaneromphalous; aperture unknown.

Remarks. We tentatively assign the studied specimens to Worthenia pagoda , based on the whorl profile, the presence of three nodular spiral ribs on the upper whorl face and the nodular selenizone. Species with a similar whorl profile belonging to Worthenia are more common in the Triassic e.g., W. annamensis Mansuy, 1913 b from Tonkin, Vietnam but are very rare in the Permian. W.? psiche ( Gemmellaro, 1889) from the Permian of Italy has a similar shape but have only two spiral ribs on the upper whorl face.

Figures

FIGURE 14. A–I, Worthenia humiligrada sp. nov. A–D, ESKU-19-LP 22. E–F, ESKU-19-LP 33. G–H, ESKU-19-LP 23. I, ESKU-19-LP 34. J–N, Worthenia cf. pagoda Mansuy, 1912, J, ESKU-19-LP 17. K–N, ESKU-19-LP 66. O–S, Worthenia sp., ESKU-19-LP 88. Scale bars represent: 2 mm (A, B, G, H, I, K, L, O); 1 mm (C, D, J, M, N, P–S); 5 mm (E, F).