Microdoma conicum Meek & Worthen, 1867

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 : 26-27

Microdoma conicum Meek & Worthen, 1867

( Fig. 19 A–C)

Microdoma conicum Meek & Worthen, 1867: 269 , pl. 9, fig. 1; Knight 1933 a: 48–49, pl. 9, fig. 1; Batten 1995: 25, fig. 34.

Material. One specimen: ESKU-19- LP 69.

Dimensions (mm): ESKU-19- LP 69: height = 4.5; width = 3.9.

Description. Shell conical, turbiniform consisting of c. 3 whorls (apex and early teleoconch whorls missing); whorl face nearly straight to slightly convex; periphery low on whorl just above suture; whorls ornamented by several collabral ribs which are separated in three rows of coarse nodes by two spiral grooves; suture shallow; base rounded and convex without ornament; seemingly minutely phaneromphalous; aperture sub-oval.

Remarks. The present material is very close to Microdoma conicum Meek & Worthen, 1867 as illustrated by Knight (1933 a) from the Pennsylvanian of Missouri and by Batten (1995) from the Pennsylvanian of Texas, USA. The feature of ornamentation in the later whorls is identical with this species, although the present material lacks the early whorls. This species has been known only from the Pennsylvanian of USA. This is the first report of this species in the Palaeo-Tethys.

Figures

FIGURE 19 A–C, Microdoma conicum Meek & Worthen, 1867, ESKU-19-LP 69. All scale bars represent 1 mm.