Mercuria tingitana Gloeer , Boeters & Walther, 2015

Boulaassafer, Khadija, Ghamizi, Mohamed & Delicado, Diana, 2018, The genus Mercuria Boeters, 1971 in Morocco: first molecular phylogeny of the genus and description of two new species (Caenogastropoda, Truncatelloidea, Hydrobiidae), ZooKeys 782, pp. 95-128 : 96-98

Mercuria tingitana Gloeer, Boeters & Walther, 2015

Examined material.

MOROCCO. Paratypes (two females): UGSB 17658, Tangier at 11 km towards Ksar es Seghir, 22/03/2014 (35°49.008'N, 5°43.643'W).

Revised diagnosis.

Shell ovate-conic, whorls 4-5; periostracum greyish; body whorl large, convex, approx. three-quarters of shell length; aperture ovate and complete; umbilicus narrow, not covered by the inner lip; central radular tooth formula 4 –C–4/1– 1; bursa copulatrix pyriform to elongate, with a short duct; one seminal receptacle elongate, without duct; penis small, black pigmented; penial appendix as long as penis, slightly pigmented, base wide, distally positioned on inner edge of penis.

Description.

Shell ovate-conic, whorls 4-5, height 2.9-3.6 mm (Figure 5A; Suppl. material 1: Table 1). Body whorl large, approx. two-thirds total shell length. Teleoconch whorls shouldered, separated by deep sutures. Periostracum greyish. Aperture ovate, complete, in contact with the body whorl; inner lip thicker than outer lip; peristome margin straight (Figure 5B). Umbilicus narrow, partially covered by the inner lip.

Operculum as for genus, brownish, whorls 2.5. Muscle attachment area oval located near the nucleus (Figure 5C, D). Radula length intermediate, approx. 600 µm long (20% total shell length), six times longer than wide, with 50-60 rows of teeth (Figure 3E; Suppl. material 1: Table 2). Central tooth formula 4 –C–4/1– 1; central cusps tongue-shaped. Lateral tooth formula 3 –C– 3; central cusp long, V-shaped (Figure 3 F–H). Inner marginal teeth with 15-16 pointed cusps. Outer marginal teeth with 21-23 cusps (Suppl. material 1: Table 2).

Animal black pigmented except for neck and eye lobes. Ctenidium well-developed, with 19-23 gill filaments, occupying almost entire length of the pallial cavity. Osphradium elongate, positioned posterior to middle of ctenidium (Figure 6A). Stomach nearly as long as wide; style sac slightly shorter than stomach and surrounded by an unpigmented intestine (Suppl. material 1: Table 3). Glandular oviduct approx. three times longer than wide. Capsule gland shorter and thicker than albumen gland. Renal oviduct coiled, unpigmented. Bursa copulatrix pyriform to elongate, with a short duct. Seminal receptacle small, elongate, sessile, joining renal oviduct above the insertion point with bursal duct (Figure 6B, C; Suppl. material 1: Table 4). Penis attached to central area of head. Penis and penial appendix almost equal in length. Penis black pigmented, short, and triangular. Penial appendix and base of penis unpigmented. Terminal gland small (see Glöer et al. 2015).

Distribution.

Only known from the type locality.

Remarks.

Mercuria tingitana can be distinguished from its congeners in northern Africa by its slender shell and short penis. Genetically, the closest species to M. tingitana is M. bakeri . However, both these are the most distant species to other Moroccan congeners with an uncorrected pairwise distance range of 4.7-8.5% for M. tingitana and of 4.7-6.8% for M. bakeri . Mercuria midarensis sp. n. and M. emiliana are the most genetically distant from M. tingitana according to COI divergences of 8.5% and 8.2%, respectively (Table 2).

Ecology.

See Glöer et al. (2015).