Ampezzalina, Bandel, 1993

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 : 22

Ampezzalina ? sp.

( Fig. 16 )

Material. One specimen: ESKU-19- LP 36.

Dimensions (mm): ESKU-19- LP 36: height = 8.9; width = 11.7.

Description. Shell trochiform, consisting of at least 2.5 whorl (apex missing); whorl face straight to slightly convex; whorl surface ornamented with at least seven spiral cords and equally spaced opisthocyrt fine collabral threads or strengthened growth lines; intersections between spiral cords and collabral threads forming a weak reticulate pattern with tiny nodes at intersections; six of the spiral cords equally strong; suprasutural spiral cord most prominent, representing shell periphery, with several coarse broken-off hollow spines; spines open in apertural direction, rounded convex in abapertural direction; base flatly convex, ornamented with spiral cords separated by concave interspace; the five strongest spiral cords situated at outer half of base; suture situated at outermost basal cord; basal cords evenly decreasing in prominence and more closely spaced toward umbilical area; minutely phaneromphalous; aperture not well-preserved but seemingly oblique.

Remarks. The single present shell probably represents a new species, but due to the state of preservation we refrain from erecting a new species. This shell is unique in that it has a well-developed spiny cord just above abapical suture. Spine-forming cords are known from Mesozoic vetigastropods e.g., in the family Eucyclidae (e.g., Bandelastraea Nützel & Kaim, 2014 , Ampezzalina Bandel, 1993 ). Ampezzalina Bandel, 1993 and Bandelastraea Nützel & Kaim, 2014 might represent synonyms and their type species should be restudied. The single specimen has prominent suprasutural spines similar to type species of Ampezzalina ; therefore, placed in Ampezzalina instead of Bandelastraea . Ampezzalina is so far only known from the Triassic. It is possible that the abapical spiny spiral cord of the present specimen is a selenizone and in that case it would represent a new genus. However, the preservation is insufficient to be sure.

Figures

FIGURE 16. Ampezzalina? sp., A–C, ESKU-19-LP 36. All scale bars represent 2 mm.