Acrostemma Cossmann 1889

Abstract

Genus Acrostemma Cossmann, 1889 Type species. Bulla coronata Lamarck, 1804; original designation by Cossmann (1889: 314). Eocene, France. Discussion. This genus is characterized by its strongly elongate pyriform shape with a prominent, raised, convex apical crest delimiting the deep and narrow umbilicus. It was originally known by several species from the Eocene of the Paris Basin (e.g. Cossmann 1889) but persisted at least to the Langhian in the Central Paratethys Sea (Berger 1953) and to the Serravallian in the Proto-Mediterranean Sea (Landau et al. 2013). In the northeastern Atlantic it is documented from the Aquitanian and Burdigalian (Peyrot 1932). At present the genus Acrostemma Cossmann, 1889 is considered a subjective synonym of Cylichna Lovén, 1846 by WoRMS (MolluscaBase eds. 2025c). However, this synonymy is not supported by any published research and the elevated coronate edge of the apical umbilicus is quite different to that of the type species of Cylichna, C. cylindracea (Pennant, 1777).

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