Diacavolinia angulata

Abstract

Diacavolinia angulata (Souleyet, 1852) (Figs 4 AH-AI) Diacavolinia elegans Van der Spoel, Bleeker & Kobayasi, 1993 Description. – Medium size Diacavolinia (L 2.9 mm, W 2.3 mm). Triangular shell with uninterrupted parallel ventral and dorsal lips, the latter with a marked short, bifid rostrum. Dorsal side rounded, with weak central rib. Ventral side globose, smooth. Lateral spines short and only slightly bent. Hyaline shell with brown colour especially the central part of the ventral side and the edges of the lips. Remarks. – In the study area this species is easily recognised based on the uninterrupted dorsal lip with bifid rostrum. Through its range it is variable, both in angle and shape of the dorsal lip, based on which initially D. elegans Van der Spoel, Bleeker & Kobayasi, 1993 was interpreted as representing a separate species. DNA barcoding analysis of numerous specimens (Maas et al., 2013) demonstrated this to be intraspecific variation. Distribution. – Ten shells were picked from the outer shelf sample DD92 off Sabah, four in Brunei (MES25) a single fragment on the outer shelf off Sarawak (DD29).

Authors 4

1. Han
2. J. G. M.
3. Raven Aachen

   Naturalis Biodiversity Center

   Affiliation as printed

   Research Associate, Naturalis Biodiversity Center, Leiden, The Netherlands. E-mail: han. raven @ naturalis. nl; https: // orcid. org / 0000 - 0002 - 5305 - 0795

4. David J. Marshall

   Universiti Brunei Darussalam

   Affiliation as printed

   Environmental and Life Sciences, Faculty of Science, Universiti Brunei Darussalam, Brunei Darussalam. https: // orcid. org / 0000 - 0003 - 3771 - 5950 * Corresponding author. E-mail: david. marshall @ ubd. edu. bn