Mathilda monilis O. Semper 1865
Creators: name: Harzhauser, Mathias
name: Landau, Bernard
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Mathildidae
Mathilda
Mathilda monilis

description: Mathilda monilis Semper, 1865
Figs 26A–D
* Mathilda monilis O. Semper — Semper 1865: 344, pl. 13, fig. 6.
Mathilda monilis O. Semper — de Boury 1883: 118.
Mathilda monilis O. Semp. — Boettger 1902: 155.
Mathilda monilis O. Semp. — Boettger 1902: 155.
non Mathilda monilis Semper, 1865 — Bałuk 2006: 196: pl. 7, fig. 3 [= Mathilda margaritula Semper, 1865].
Type material. Lectotype (designated herein): NHMW 1858 /0047/0039, SL: 4.7 mm, MD: 2.2 mm, Sedlec (= Porzteich) (Czech Republic), Fig. 26C. Paralectotypes: NHMW 2023 /0270/0001, SL: 4.5 mm, MD: 2.0 mm, Sedlec (= Porzteich) (Czech Republic), Figs 26B 1 –B 2. NHMW 2023 /0270/0002, SL: 3.6 mm, MD: 1.7 mm, Sedlec (= Porzteich) (Czech Republic), Fig. 26D.
Illustrated material. NHMW 1869/0013/0020, SL: 3.0 mm, MD: 1.6 mm, Coşteiu de Sus (Romania), Fig. 26A.
Additional material. 2 spec., NHMW 1876 /9911/0097, Lăpugiu des Sus (Romania).
Revised description. Small, robust, stout, conical, shell; apical angle ~31–33°. Protoconch multispiral, of about 2.5 smooth whorls, heterostrophic, nucleus not exposed, tilted at angle of about 115°. Teleoconch of at least six straight sided whorls with narrowly incised suture. Sculpture of three primary spiral cords of roughly equal strength separated by narrower interspaces; S1 slightly recessed; interspace between S1 and S2 slightly wider; S3 forming periphery. Axial sculpture of about 25 weak, slightly prosocline axial ribs with prominent rounded tubercles formed at intersections almost touching. Last whorl damaged in all available specimens.
Discussion. This species is characterized by its broad conical shape and straight-sided whorls with densely tuberculate sculpture. It is also unusual in having the whorl periphery at S3 rather than S2. Mathilda margaritula Semper, 1865 is much slenderer and differs in its cancellate sculpture. A paratype of Mathilda peyroti Cossmann & Peyrot, 1922 (MNHN.F.J05877), from the Aquitanian of France, is similar to M. monilis in its sculpture but is finer and has a more prominent mid-whorl cord (see https://science.mnhn.fr/institution/mnhn/collection/f/item/j05877?li stIndex=9&listCount=26). Among the extant Mediterraean fauna, Mathilda retusa Brugnone, 1873 is most similar to M. monilis but S1 is more recessed in M. retusa and its suture is more deeply incised.
Paleoecology. Unknown; probably middle to outer neritic.
Distribution. Only known from the Langhian equivalent of the Badenian in the Sea.
Central Paratethys Sea. Middle Miocene (Badenian): North Alpine Carpathian Foreland Basin: Sedlec (= Porzteich) (Czech Republic) (hoc opus); Făget Basin: Coşteiu de Sus, Lăpugiu de Sus (Semper 1865; Boettger 1902).
description: Published as part of Harzhauser, Mathias & Landau, Bernard, 2023, The Architectonicidae and Mathildidae (Gastropoda, Heterobranchia) of the Miocene Paratethys Sea-victims of the Miocene Climatic Transition, pp. 1-74 in Zootaxa 5370 (1) on pages 52-53, DOI: 10.11646/zootaxa.5370.1.1, http://zenodo.org/record/10147814