Sphincterochila (Albea) tunetana (Pfeiffer, 1850)

Abbes, Intidhar, Nouira, Said & Neubert, Eike, 2011, Sphincterochilidae from Tunisia, with a note on the subgenus Rima Pallary, 1910 (Gastropoda, Pulmonata), ZooKeys 151, pp. 1-15 : 4-6

Sphincterochila (Albea) tunetana (Pfeiffer, 1850) Figs 15 B–D 7, 8

Helix tunetana Pfeiffer, 1850: 70 [Habitat circa Tunis Africae].

Helix tunetana , - Pfeiffer 1853: 346-347, pl. 134, fig. 3-4 [syntype figured].

Helix tunetana , - Reeve 1854: pl. CXCIX fig. 1400.

Helix tunetana , - Letourneux and Bourguginat 1887: 94.

Albea tunetana , - Pallary 1939: 67.

Type specimens

No type specimens could be traced in any larger museum collection with holdings of specimens from the Pfeiffer collection. One syntype was figured by Pfeiffer in 1853 ("in der Gegend von Tunis, aus H. Cuning’s Sammlung"), another without reference to the collector by Reeve in 1854.

Material examined

Ichkeul National Park 13.02.08, coll. Abbes/15.

Diagnosis

Shell nearly flat or with slightly elevated spire, upper shell surface with very coarse sculpture; last whorl keeled, aperture lenticular; umbilicus open to completely closed.

Description

Shell medium sized, nearly flat or with slightly elevated spire; shell with 4 ½ flattened and regularly growing whorls; white yellowish in colour; suture shallow; upper shell surface with coarse and oblique, rib-like sculpture, lower shell surface with irregular wrinkles; last whorl sharply keeled; aperture lenticular; peristome discontinuous, parietal callus lacking; lip slightly thickened, often slightly reflected on the lower and columellar side; umbilicus wide and open, surrounded by a cord like ridge; there are specimens where the columellar reflection completely obscures the umbilicus.

Measurement.

(n = 15). H = 8.5 mm ± 1.37; D = 16.58 mm ± 0.79.

Anatomy of genital organs

(Figs 5 B–D). Penis thick club-shaped, with a short penial coecum, epiphallus long reaching only twice the length of the penis, penial papilla missing; flagellum short; musculus retrator penis inserts at the distal third of the epiphallus.

Stimulator gland very large, stimulator appendix branches off in a basal position; stimulator duct short, pointing into the genital atrium with a large papilla (Fig. 5D).

Vagina very short and slender; pedunculus short, reaching a third or even less of the lenght of the whole bursa copulatric complex, diverticulum short to reduced, bursa copulatrix a well rounded vesicle.

Distribution

This species was only reported from Tunisia by Letourneux and Bourguignat (1887) and from Algeria by Bourguignat (1864).

Remarks

At first glance, Sphincterochila tunetana may be confused with a species of the Hygromiidae , Helicopsis (Xeroleuca) degenerans Mousson, 1872, from Morrocco (Fig. 9) because of the depressed shape of the shell, the magnificent sculpture, and the open umbilicus. However, the small-sized protoconch of Helicopsis degenerans is a good character to discriminate it from Sphincterochila tunetana . Affiliation of the latter species to the Sphincterochilidae was already suggested by Pallary (1901, 1910).

The differences in morphology of the genital organs to Sphincterochila candidissima are quite large: Sphincterochila candidissima has a much longer epiphallus and flagellum, and the diverticulum in Sphincterochila tunetana seems to be reduced, and its pedunculus is considerably shorter than in Sphincterochila candidissima .