Yunnania inflata, Ketwetsuriya & Karapunar & Charoentitirat & Nützel, 2020

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 : 24-25

Yunnania inflata sp. nov.

( Fig. 18 A–J)

Etymology. From Latin inflata, for having swollen, inflated whorl.

Holotype. ESKU-19-LP 9 .

Paratypes. ESKU-19- LP 8, 16, 21, 38, 65, 98, two juvenile specimens: ESKU-19- LP 205, 212.

Dimensions (mm): ESKU-19- LP 8: height = 4.3; width = 3.9; apical angle = 87º. ESKU-19- LP 9: height = 5.0; width = 4.1; apical angle = 85º. ESKU-19- LP 16: height = 3.2; width = 2.8; apical angle = 80º. ESKU-19- LP 21: height = 8.9; width = 5.6; apical angle = 75º. ESKU-19- LP 38: height = 4.9; width = 3.9; apical angle = 87º. ESKU- 19- LP 65: height = 5.4; width = 4.9; apical angle = 85º. ESKU-19- LP 98: height = 4.5; width = 4.6; apical angle = 87º. ESKU-19- LP 205: height = c. 1.9; width = c. 1.9; apical angle = 90º. ESKU-19- LP 212: height = c. 1.8; width = c. 1.9; apical angle = 96º.

Type locality and stratigraphical range. Erawan Hill, Chong Sarika sub-district, Phatthana Nikhom district,

located about 13 km east of Lopburi Province, Central Thailand ( Fig. 1 ), Khao Khad Formation, Saraburi Group, Middle Permian, Roadian.

Description. Shell small, turbiniform, cyrtoconoid with strong reticulate ornament; holotype comprising c. 5 whorls; first three to four whorls slightly convex, evenly rounded and low-spired, dome-shaped, without ornament or ornamented by very faint spiral threads; later whorls distinctly convex and inflated; periphery at about mid-whorl; suture impressed; whorls convex, embracing at about mid-whorl, slightly below periphery; whorls ornamented with about 10 evenly spaced spiral cords and numerous weaker collabral axial ribs; axial ribs prosocline slightly prosocyrt; spiral cords and axial ribs forming reticulate ornament with slightly nodular intersections; nodes strongest near upper suture; base convex with evenly rounded transition to whorl face, ornamented with up to 10 strong equally spaced spiral cords; base convex, anomphalous; aperture approximately circular; columellar lip straight.

Remarks. Yunnania inflata sp. nov. closely resembles Yunnania meridionalis Mansuy, 1914 (p. 41, pl. 4, fig. 10a–c) from the Permian Productus Limestone of Cambodia in shell shape, size and ornament on whorl face and base but Y. meridionalis has a deeper suture, its spiral cords are more pronounced and the axial ribs are less pronounced and less numerous Y. meridionalis has also been reported from another Permian deposits of Cambodia by Delpey (1941) and from the Permian of Malaysia ( Batten 1979). Y. inflata sp. nov. also resembles Y. pulchra Nützel & Ketwetsuriya, 2016 from the Middle Permian of the Tak Fa Limestone from Thailand ( Ketwetsuriya et al. 2016, p. 499, fig. 16A–H) in shell shape and ornamentation but Y. pulchra has fewer but stronger spiral cords, the axial ribbing is denser, axial ribs are sharper, it has more convex and inflated whorls as well as the axial ribs of Y. pulchra are more distinct, dense and thinner. Y. inflata sp. nov. has much more inflated whorls than Y. meridionalis and Y. pulchra . Y. inflata sp. nov., improves our knowledge on the distribution of Yunnania in this region of the Indochina Terrane.

Figures

FIGURE 18. A–J, Yunnania inflata sp. nov. A–B, ESKU-19-LP 9, holotype; C–G, ESKU-19-LP 65, paratype. H–J, juvenile specimens, H–I, ESKU-19-LP 205. J, ESKU-19-LP 215. K, Araeonema cf. tenuistriata (Netchaev, 1894), ESKU-19-LP 99. All scale bars represent 1 mm.

FIGURE 1. Geological map of the study location at Erawan Hill, Chong Sarika sub-district, Phatthana Nikhom district, located about 13 km east of Lopburi Province, Central Thailand.