Acrostemma kuehnelti

Abstract

Acrostemma kuehnelti (Berger, 1953) Figs 39A 1 –A 3 Retusa (Acrostemma) kühnelti n. sp. — Berger 1949: 82 [nomen nudum]. * Retusa (Acrostemma) kühnelti n. sp. — Berger 1953: 96, pl. 16, fig. 31. R [etusa]. (A [crostemma). kühnelti Berg.— Sieber 1958: 163. Type material. Holotype, NHMW-ZOO-MO-75000-E-42897, SL: 5.2 mm, MD: 1.6 mm, Vienna / Ottakring (Austria), illustrated in Berger (1953: pl. 16, fig. 31), Figs 39A 1 –A 3. Revised description. Medium sized, strongly elongate, very slender pyriform shell (SL/MD = 3.2), only last whorl visible. Protoconch unknown. Last whorl subcylindrical, weakly convex; periphery placed just above mid-whorl (SL/ PH = 1.9), almost straight in adapical third, forming angle of about 23°. Rounded at slowly contracting base. Apex sharply truncated, moderately broad (MD/ApD = 1.9), apical plane strongly oblique (AP = 19°), deeply and narrowly umbilicate, delimited by prominent, round-edged apical crest. Surface of apical crest with broad, low, short growth lines. Sculpture of numerous moderately deep, partly punctate spiral grooves over entire last whorl. Broad, flat spiral cords occasionally bifid. Aperture longer than shell, very narrow down to mid-whorl (MD/AW = 8.3), weakly widening anteriorly (MD/MAW = 2.7), resulting in moderate expansion rate (ER = 3.1). Outer lip thin, relatively high, very narrowly alate apical extension. Columella obscured by sediment. Columellar callus forming delicate, narrow rim delimiting umbilical chink. Discussion. This species differs from all congeners in its very slender outline and prominent spiral sculpture. Acrostemma anatolica sp. nov. is broader, the apical crest is more prominent, and the spiral grooves become increasingly wider spaced adapically on the last whorl. Paleoenvironment. Probably middle neritic based on co-occurring assemblage (own data, M.H.). Distribution in Central Paratethys. Badenian (Middle Miocene): Vienna Basin: Vienna /Ottakring (Austria) (Berger 1953).

Authors 3

1. Mathias Harzhauser

   Natural History Museum Vienna

   Affiliation as printed

   Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria mathias. harzhauser @ nhm. at; https: // orcid. org / 0000 - 0002 - 4471 - 6655

2. Bernard Landau Aachen

   University of Lisbon · Instituto Dom Luiz · Naturalis Biodiversity Center

   Affiliation as printed

   Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, Netherlands; Instituto Dom Luiz da Universidade de Lisboa, Campo Grande, 1749 - 016 Lisboa, Portugal; and International Health Centres, Av. Infante de Henrique 7, Areias São João, P- 8200 Albufeira, Portugal bernardmlandau @ gmail. com; https: // orcid. org / 0000 - 0002 - 7768 - 8494

3. Manuel António E. Malaquias

   University of Bergen · Natural History Museum Vienna

   Affiliation as printed

   Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria mathias. harzhauser @ nhm. at; https: // orcid. org / 0000 - 0002 - 4471 - 6655 & Department of Natural History, University Museum of Bergen, University of Bergen, PB 7800, 5020 - Bergen, Norway manuel. malaquias @ uib. no; http: // orcid. org / 0000 - 0002 - 9668 - 945 X & Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria mathias. harzhauser @ nhm. at; https: // orcid. org / 0000 - 0002 - 4471 - 6655