Pseudozygopleura, Knight, 1930

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 : 37

Pseudozygopleura ? sp.

( Fig. 24 C–D)

Material. One specimen: ESKU-19- LP 63.

Dimensions (mm): ESKU-19- LP 63: height = c. 9.2; width = 2.6.

Description. Shell high-spired, slender, turritelliform, slightly cyrtoconoid comprising at least 8 whorls with apex missing; whorls twice as wide as high; whorls gently convex, ornamented by straight faint collabral ribs numbering about 10 to 14 per whorl; ribs presumably reduced on last preserved whorl; sutures shallow but distinct; transition to base gradually convex; base rounded; anomphalous; aperture elongated suboval (higher than wide) with indistinct siphonal notch, columellar lip nearly straight.

Remarks. This single specimen resembles several species from the Pennsylvanian of the USA ( Knight 1930; Hoare & Sturgeon 1985) but the preservation is insufficient for an identification. Pseudozygoppleuridae have a typical larval shell and hence knowledge of the protoconch is needed for a save family and genus assignment. Similar shells as the present one may also occur in Palaeostylidae and other groups. Several species that have been recorded from the Permian of the Palaeo-Tethys from Thailand ( Ketwetsuriya et al. 2016) and Malaysia ( Batten 1985) have been reported but those species have a more distinct axial ornament.

Figures

FIGURE 24. A–B, Palaeostylus sp., ESKU-19-LP 7. C–D, Pseudozygopleura? sp., ESKU-19-LP 63. Scale bars represent: 1 mm (A–B); 2 mm (C–D).