Sphincterochila (Albea) candidissima (Draparnaud, 1801)

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 : 2-4

Sphincterochila (Albea) candidissima (Draparnaud, 1801) Figs 1-45A

Helix candidissima Draparnaud, 1801: 75.

Zonites candidissimus , - Bourguignat 1863: 85.

Zonites candidissimus maxima Bourguignat, 1863: 87.

Zonites candidissimus , - Bourguignat 1864: 322.

Zonites candidissima , - Bourguignat 1868: 10.

Leucochroa candidissima , - Issel 1885: 6.

Leucochroa candidissima , - Letourneux and Bourguignat 1887: 3.

Leucochroa baetica , - Letourneux and Bourguignat 1887: 4 [non Helix baetica Rossmässler, 1839].

Leucochroa baetica var. tunetana Letourneux & Bourguginat, 1887: 4 [Guelaat es Snam; secondary homonym of Helix tunetana L. Pfeiffer, 1850].

Leucochroa candidissima , - Ktari and Rezig 1976: 37.

Type specimens

candidissima: syntype NHMW 14810, D = 17.95 mm [no original label left, type locality: France, "en Provence et dans le Comtat"; maxima: not identifiable in MHNG; tunetana: MHNG 3896, D= 20.0 mm.

Material examined

Bizerte: Aïn Ezzommita, N 36.87628, E 9.64936, 23.12.08, coll. Abbes/8; Barrage El Khadhra, N 36.16681, E 10.06214, 14.12.08, coll. Abbes/4; Barrage El Khirba, N 37.16354, E 10.0955, 21.02.08, coll. Abbes/6; Utique, N 37.04007, E 1003244, 02.03.05, coll. Abbes/9; Nabeul: NEUB 02879, Wadi NE of the city, 36°28' N 10°45'50" E, 26.-31.12.1993, leg. B. & R. Kinzelbach; Ariana, Djebel Bejewa, N 37.03027, E 10.027040, 11.04.08, coll. Abbes/12; Ichkeul National Park, N 37. 11255, E 9.34953, 04.03.07, coll. Abbes/7; Tunis: NEUB 02878, Tunis, 20 km S of Hamamet, 02.03.1993, leg. J. Gugel; Ben Arous: Djebel Boukornine, N 36.4122, E 10.2125, 4.01.07, coll. Abbes/8; Djebel Reças, N 36.59382, E 10.3194, 09.10.08, coll. Abbes/5; Nabeul: Assomaa, N 36.52552, E 10.77991, 04.02.09, coll. Abbes/3; Korbos, N 36.82950, E 10.57071, 03.02.09, coll. Abbes/8; Zaghouan: Djebel Zaghouan, N 36.37543, E 10.11868, August 2008, coll. Abbes/9; Djebel Zriba, N 36.37, E 10.11, 20.08.08, coll. Abbes/1; Beja, Nefza, N 97.0041, E 9.08434, 4.4.05, coll. Abbes/2; Jendouba, Ouechteta, N 36.96445, E 9.01706, 24.12.08, coll. Abbes/4; El Kef: Djebel Boujeber, N 35.73791, E 8.27292, 26.12.08, coll. Abbes/3; Sousse, Tekrouna, N 36,085749, E 10,182551, 25.08.2008, coll. Abbes/2; Siliana: Ain tejra, N 36.26, E 9.43, 07.11.08, coll. Abbes/16; Kairouan: Aïn Chrichira, N 35.63908, E 9.80950, 14.12.08, coll. Abbes/9; Sbikha, N 35.98503, E 10.03106, 14.12.08, coll. Abbes/17; Djebel Serj, N 36.04555, E 9.63311, 28.12.08, coll. Abbes/2; Mehdia, Dowwira, N 35.26905, E 11.09773, 19.03.09, coll. Abbes/4; Sidi Bouzid: Bouhedma National Park, N 34.185722, E 245520, 11.05.08, coll. Abbes/10; NEUB 02875, Jebel Bou Hedma, 15-18.03.1993, leg. J. Gugel; NEUB 02876, Sabkhat Mecheguig, ca. 50 km S Kairouan, 02.03.1993, leg. J. Gugel; Kasserine: Djebel Chaambi, N 35.10139, E 8.40486, 30.11.08, coll. Abbes/8; Table de Jugurtha, 20.05.09, coll. Abbes/11; Kebili: NEUB 02874, big erg close to Ksar Rhilane, 32°59' N 9°38' E, 09.03.1993, leg. J. Gugel; NEUB 02880, Kebili, 30 km S of the city, 33°29'N, 9°02'E, 12.03.1993, leg. J. Gugel; Tataouine: NEUB 02877, Tataouine, 32°56'N, 10°27'E, 05.03.1993, leg. J. Gugel; NEUB 02881, Gouvernorat de Tataouine, Ramadah, 32°19'N, 10°24'E, 05.03.1993, leg. J. Gugel.

Diagnosis

Shell medium sized, helicoid, globose, shell walls thick, external surface slightly wrinkled, last whorl rounded, aperture rounded, umbilicus closed.

Description

(Figs 2-4). Shell medium sized, helicoid, globose, spire slightly depressed; shell colour white; protoconch consisting of two smooth whorls; shell walls thick, teleoconch of six nearly flattened whorls, last whorl large, rounded and sometimes inconspicuously keeled and slightly descending below the periphery of the shell; suture shallow to moderately deep; upper teleoconch surface smooth or with fine irregularly shaped wrinkles; aperture dorsoventrally depressed; peristome discontinuous, only slightly thickened; umbilicus closed by a thick reflection of the columellar peristome. - Measurement (n = 20). H = 17.3 mm ± 2.46; D = 20.57 mm ± 1.33.

Anatomy of genital organs

(Fig. 5A). Penis thick with a short and blunt penial coecum, epiphallus a long and cylindrical slender tube reaching 4 × the length of the penis, penial papilla missing; flagellum relatively long; Mrp inserts at the distal third of the epiphallus.

Stimulator gland large, stimulator appendix branches off in a basal position; stimulator duct short, pointing into the large genital atrium with a small papilla.

Vagina very short and slender; pedunculus reaching half of the lenght of the whole bursa copulatric complex, diverticulum short and thickened, bursa copulatrix a well rounded vesicle.

Geographic range

This is a species of western Mediterranean distribution ( Giusti et al. 1995), but its actual presence in NW Africa has to be corroborated by a serious investigation of all specimens available including dissections of preserved specimens. Its hitherto known distribution in Tunisia is given in Fig. 1.

Remarks

The species Sphincterochila baetica ( Rossmässler, 1839), which was described from Spain (between Almeria and Venta del Pobre) has been reported for Northwestern Africa from Morocco to Tunisia ( Bourguignat 1863; Letourneux and Bourguignat 1887; Morlet 1881; Rour et al. 2002). We here figure one syntype of Helix baetica (SMF 7669, Fig. 6) to show the differences between the two species: next to the size difference, shells of Sphincterochila candidissima are usually smooth or show a fine sculpture of small wrinkles, while Sphincterochila baetica has much stronger and coarse wrinkles or is even malleated, particularly on the upper whorls; in addition, shells of Sphincterochila candidissima ususally have a rounded periphery of the last whorl (exceptions see our Figs 3 and 4), while Sphincterochila baetica shows a bluntly angulated last whorl. The shell of Leucochroa baetica var. tunetana might mislead to an identification as Sphincterochila baetica as it is quite large and shows the angulation. However, it has the typical finely striated surface sculpture of Sphincterochila candidissima , and thus can be synonymised with this species. The collection of Bourguignat in Geneva did not contain any specimen from northwestern Africa that could positively be identified with Sphincterochila baetica . However, his collection is particularly weak concerning shells from Morocco, so we are not able at the moment to judge about records from Algeria or Morocco. So far, all specimens we have seen from Tunisia can be identified with Sphincterochila candidissima .

The morphological details of the genital organs of dissected specimens from Tunisia compare very well with those presented by Forcart (1972: figs 8, 9) from southern France and Giusti et al. (1995) from Malta.