A new Nigerian hunter snail species related to Ennea serrata d’Ailly, 1896 (Gastropoda, Pulmonata, Streptaxidae) with notes on the West African species attributed to Parennea Pilsbry, 1919

By

Winter, Anton J. de
de Gier, Werner

Type

Article

Date of Publication

2019

Original Publication

ZooKeys

Volume

840

Pages

21-34

Subjects

Afrotropical region , Cameroon , computerised tomography , land snail , Liberia , Nigeria , Ptychotrema , shell morphology , Stylommatophora , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.840.33878

 

Abstract

Enneanigeriensissp. n. is described from southeastern Nigeria on the basis of external and internal shell morphology. Following Pilsbry’s formal criteria of a single palatal fold and corresponding external furrow, the new species may be assigned to Parennea. Enneanigeriensissp. n. exhibits substantial similarity with E.serrata, a species from Cameroon, in the cylindrical shell shape, crenulate suture, and internal shell morphology, indicating that the two species are closely related. CT scanning confirmed the presence of only a single palatal fold in E.nigeriensissp. n. and two in E.serrata. In spite of this, the Nigerian species is provisionally assigned to Ennea rather than Parennea, suggesting that the characters used to define Ennea and Parennea are insufficient to delimit natural groups of species. The holotype of E.serrata is examined for the first time since its description in 1896 and a redescription of the species is provided based on the two shells hitherto known.<br> Study of the original specimens recorded as Ptychotrema (Parennea) sulciferum by Degner from Liberia reveals these to belong to Enneacf.thompsonae. The Nigerian shell recorded by van Bruggen as Ptychotrema (Parennea) aequatoriale proved to be a specimen of Enneacf.perforata. As a result, no species attributable to Parennea now appear to be known in West Africa; in contrast, numerous species are known from central and eastern Africa.