Jeanclaudella zigrinata ( Conti & Fischer, 1984 ), 2025

Jeanclaudella zigrinata ( Conti & Fischer, 1984) new comb.

Fig. K–Q

v* 1984 Aaleniella zigrinata Conti & Fischer , p. 138, pl. 2, figs 15a–c.

Material. Holotype MPUR MAC33 A , Paratype MPUR MAC33 B. Case Canepine ( Martani Mountains , Umbria, central Italy), lower Bajocian, Stephanoceras humphriesianum Zone .

Description. The shell is small (max height 2.9 mm; width 2.6 mm) trochiform, almost conoidal in outline and composed of at least four whorls. The protoconch is not preserved. The last whorl is 0.72 of the height of the shell. The early preserved whorl is well rounded. The surface of the subsequent whorls is flat and becomes slightly concave on the last whorl. The suture is almost flush on the adult part of the shell. The periphery is sharply angulated and marked by a thin spiral keel. The base is convex, moderately inflated and narrowly phaneromphalous. The aperture is seemingly rounded-quadrangular. The peristome is discontinuous and with a thin parietal inductura. The outer lip is thin and angulated at the periphery. The columellar lip is seemingly slightly arched. The ornament of the earliest preserved whorls consists of collabral riblets. The adult whorls bear somewhat thin, almost straight and prosocline collabral riblets separated by wider interspaces. During the growth, the number of the collabral riblets per whorl increases from about 20 to about 40. The collabral ribs form small nodes on the peripheral keel and vanish on the median part of the whorl surface. The base is ornamented by five, sharp, widely and regularly spaced spiral threads. The more adaxial spiral thread is stronger than the others and encircles the umbilical region. The growth lines are not visible.

Remarks. Although the apical part of the holotype is slightly smoothened by erosion, the evenly convex shape and the collabral ornament of the earliest whorls are still partly recognizable. In the paratype the apical shell is broken. In both specimens the peristome is incomplete. Jeanclaudella zigrinata ( Conti & Fischer, 1984) differs from Jeanclaudella umbriensis ( Conti & Fischer, 1981) , in having an evenly conoidal outline of the shell with less inflated base, and in the much thinner and more numerous collabral riblets. In addition, the umbilical cavity is encircled by a spiral keel whereas in J. umbriensis it bears granulate collabral elements.