Belgrandiellopsis, Khalloufi & Béjaoui & Delicado, 2020

Khalloufi, Noureddine, Béjaoui, Mustapha & Delicado, Diana, 2020, Two new genera and three new subterranean species of Hydrobiidae (Caenogastropoda: Truncatelloidea) from Tunisia, European Journal of Taxonomy 648 (648), pp. 1-27 : 8-9

Genus Belgrandiellopsis gen. nov.

urn:lsid:zoobank.org:act:6073FD1F-91C0-4C93-B1CB-09AA54B1FABD

Type species

Belgrandiellopsis chorfensis sp. nov., by present designation.

Diagnosis

Shell small (maximum length slightly exceeding 2 mm), ovate-conic to elongate-conic, with obtuse and planispiral protoconch; whorls slightly convex, with weak sutures. Penultimate whorl tall relative to remaining whorls. Aperture pyriform to ovate, complete, angled on top and often fused to the body whorl. Umbilicus closed by inner lip. Operculum corneous, whitish to yellowish, thin, pliable, elongateellipsoidal, spiral, paucispiral, with submarginal nucleus. One pair of small triangular basal cusps on radular central tooth. Ctenidium well developed. Stomach with a small gastric (posterior) caecum. Presence of bursa copulatrix; unpigmented renal oviduct with a spherical pouch at the end of the coiled section; two seminal receptacles. Penis attached to the neck behind the right eye with two glandular lobes distantly positioned, each of them bearing a terminal papilla.

Etymology

Refers to the shell similarities with the hydrobiid genus Belgrandiella ; gender feminine.

Remarks

Belgrandiellopsis gen. nov. differs from the conchologically similar genus Belgrandiella in having a strap-like penis with two glandular lobes, two seminal receptacles and one pair of basal cusps on the central radular teeth (for comparison see Szarowska 2006); from the closely related genus Bullaregia according to the presence of two lobes on the inner edge of the penis, smaller gastric caecum, shorter bursal duct, larger bursa copulatrix and in having generally a smaller number of cusps on radular teeth (see Khalloufi et al. 2017); and from Biserta gen. nov. according to its smaller shell umbilicus, longer penis with a larger distance between penial lobes, slightly smaller bursa copulatrix and longer bursal duct ( Figs 4 , 6 , 8 ). Belgrandiellopsis gen. nov. differs in its mean COI divergence by 9.3% and 8.4% from the closely related Bullaregia and Biserta gen. nov., respectively, and by 17.6% from Belgrandiella .

Figures

Fig. 4.Anatomy of Belgrandiellopsis chorfensis gen. et sp. nov. (paratypes, UGSB 17663). A. Ctenidium and osphradium. B. Stomach. C. Head of male and penis. D. Detail of penis and penis lobes (observed by transmitted light in E). F. Pallial oviduct. G. Bursa copulatrix and seminal receptacles. H. Ditto, observed by transmitted light. Anatomical abbreviations explained in the text.

Fig. 6. Anatomy of Belgrandiellopsis secunda gen. et sp. nov. (paratypes, UGSB 17666). A. Ctenidium and osphradium. B. Stomach. C. Head of male and penis. D. Detail of penis and penis lobes. E. Pallial oviduct. F. Bursa copulatrix and seminal receptacles. G. Ditto, observed by transmitted light. Anatomical abbreviations explained in the text.

Fig. 8. Anatomy of Biserta putealis gen. et sp. nov. (paratypes, UGSB 17664). A. Ctenidium and osphradium. B. Stomach. C. Head of male and penis. D. Detail of penis and penis lobes. E. Pallial oviduct. F. Bursa copulatrix and seminal receptacles. G. Ditto, observed by transmitted light. Anatomical abbreviations explained in the text.