Donaldospira, Batten, 1966

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

Donaldospira ? sp.

( Fig. 25A )

Material. One specimen: ESKU-19- LP 85.

Dimensions (mm): ESKU-19- LP 85: height = 10.4; width = 3.1.

Description. Turritelliform, high-spired, slender shell, comprising about five whorl (apex missing); whorls gradually increasing; whorls generally gently convex with median angulation; whorls with two fine spiral cords new near upper and lower suture; third cord strongest, situated at mid-whorl, forming crest-like periphery; upper whorl face forming evenly concave ramp; lower whorl face slightly concave, inwardly sloping from angulation to suture; suture distinct; base evenly rounded; anomphalous; aperture elongated suboval in shape with thin lip, columellar lip nearly straight.

Remarks. Due to the preservation a possibly present selenizone on the angulation at mid-whorl, this specimen can only be assigned to Donaldospira tentatively. The Permian species Murchisonia (Donaldospira) malaysia Batten, 1985 from Perak, Malaysia is similar but has a straighter whorl face and finer spiral cords on the whorls above and below the selenizone. M. gubleri Delpey, 1941 (p. 367, fig. 41) from the Lower Permian Sisophon Formation, Cambodia is similar but it has a much more protruding peripheral carina and lacks spiral cords near the sutures. M. fischeri Stuckenberg, 1905 as illustrated by Delpey (1941) is much similar in whorl profile but it develops selenizone at the periphery which is bordered by two spiral ribs.

Figures

FIGURE 25. A, Donaldospira sp., ESKU-19-LP 85. B–E, Knightella irregularis (Longstaff, 1933), B–C, ESKU-19-LP 41. D–E, ESKU-19-LP 84. F–H, Protostylus sp., F, ESKU-19-LP 39. G–H, ESKU-19-LP 64. I–N, Trypanocochlea lopburiensis sp. nov. I, M, ESKU-19-LP 210, holotype; oblique view of early whorls to show protoconch. J, ESKU-19-LP 201, paratype. K, ESKU-19-LP 203, paratype. L, ESKU-19-LP 206, paratype; lateral view of early whorls to show protoconch. N, ESKU-19-LP 221, paratype. O–R, Streptacis? khaokhadensis sp. nov., O–P, ESKU-19-LP 214, holotype. Q–R, ESKU-19-LP 213, paratype. Scale bars represent: 2 mm (A–H); 200 μm (I–R).