Caecum glabrum
Creators: name: Vannozzi, Angelo
name: Pizzini, Mauro
name: Raines, Bret
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Caecidae
Caecum
Caecum glabrum

description: Caecum cf. glabrum (Montagu, 1803)
Figs 16A–C, 17, 22R, 23R, 25I
Caecum glabrum: Sowerby III 1892: 38.
Caecum glabratum: Bartsch 1915: 117.
Caecum glabrum: Turton 1932: 126.
Material examined: SOUTH AFRICA: Western Cape: 4 sh (1 broken), Knysna, Gericke Point, Sedgefield (NMSA W 9658); Eastern Cape: 1 sh, Port Alfred, (J. Hutt colln, ex Albany Museum, 1980) (NMSA W 9657).
Comparative material examined: C. glabrum: SWEDEN: 3 sh (2 broken), Persgrund, Koster Area, Bohuslän, 20– 40 m, sand/clay, rectangular dredge, leg. C. Schander vii.1994 (MP); U.K.: 8 sh (4 broken), Wales, Plymouth, Duke Rock, - 8–10 m, leg. M. Thollesson & L. Gustavsson iv.1994 (MP); FRANCE: 13 sh, St. Malo, - 15 m, leg. W. Segers 1978 (MP); 50 sh, Morbihan near Quiberon I., Penthièvre, Sauvage Coast, leg. Ron Voskuil 25.vii.1990 (MP); SPAIN: 3 sh, Laredo, viii.1992 (MP); MOROCCO: 3 sh, Rabat (MP); MAURITANIA: 2 sh, Banc d’Arguin, leg. E. Rolán (MP); SENEGAL: 1 sh, Gouye Teni M’Both, - 25 m, sandy bottom clean and rocks, leg. J. Pelorce (MP); 1 sh, Grand Thiouriba, 40 m, sandy bottom clean and very large rocks, leg. J. Pelorce (MP); 4 sh, Cape Verde, shelly sand by diver, leg. Pelorce ix.1995 (MP); West Sahara: 10 sh, leg. J. Pelorce (MP); Cape Verde: 10 sh (1 larval), Ilha de São Vicente, Porto Mindelo, leg. J. Pelorce (MP); 1 sh, Ilha de Sal, Mordeira, - 5 m, leg. J. Pelorce (MP); 1 lv, Ilha da Boa Vista, Sal Rei, Baixona, Derrubado, Rife de Chaves, Baia Teodora, Porto Ferreiro, - 3 m, leg. J. Pelorce (MP).
Distribution: C. glabrum is known from the Atlantic coasts of Europe and western Africa up to Senegal. Specimens tentatively attributed to this species were found on the southern coast of South Africa (Fig. 17). Further study is required to ascertain their identity.
Remarks: Caecum glabrum is a well-known species described from English coasts and occurs along the Atlantic European coasts from Norway to Spain, and western African coasts from Morocco to Senegal, although it seems absent from Canary Is. (Aartsen 1977; Fretter & Graham 1978; Nofroni et al. 1997; van der Linden & Moolenbeek 2000; unpublished data). Additionally, it was reported for the Italian Miocene (Moroni & Ruggieri 1985). However, it is unclear whether Montagu’s species coincides with C. glabrum as commonly intended, since the type could not be found in the NHMUK (K. Way, pers. comm.). Sowerby II (1859, pl. XV, fig. 7) illustrates C. glabrum from English coasts with the comment “rare and smooth”. Some years later (1892) Sowerby III reports this species from South Africa at Port Elizabeth; Bartsch (1915) cites this species al Port Alfred under the name C. glabratum. Conversely, Turton (1932) reports this species as common at Port Alfred. We found only a few specimens in the rich material stored in the NMSA.
South African specimens fit well with C. glabrum as commonly intended and only minor differences can be accounted for, such as a shorter and proportionally wider tube, a more pronounced swelling at the aperture and a duller surface. Notwithstanding these minor differences, the identification of South African specimens as C. glabrum is problematic. In fact, both present and historical records of this species in South Africa, ignoring possible misidentifications, come from the central and eastern part of the southern coast of South Africa, and there is no information about its occurrence either in the western part of the southern coast or along the western coast of Africa from Guinea to western South Africa.
With the present knowledge coming from studies on other groups, it seems unlikely to find species with a continuous distribution going from western Africa to southern South Africa. Among other well-studied molluscan families, there are only a few species with a western African or European to southern South African distribution, e.g. Talochlamys multistriata (Poli, 1795) among Pectinidae, which nevertheless shows a gap in Namibia (Dijkstra & Kilburn 2001). Furthermore, the pattern of southeastern Atlantic currents, with a northward­flowing Benguela Current and a southward­flowing Angola Current, which meet at around the Angolan-Namibian border, strongly suggests that western African and South African species are unrelated. However, the identity of European and South African populations cannot be ruled out, as it has been genetically demonstrated with a species of spider crab from the Lusitan area and South Africa (Sotelo et al. 2009).
For the time being, in the absence of a detailed study of European C. glabrum and more information coming from South African populations, we ascribe South African specimens to the European species by comparison only.
description: Published as part of Vannozzi, Angelo, Pizzini, Mauro & Raines, Bret, 2015, Revision of South African Caecidae (Mollusca: Gastropoda), pp. 99 in African Invertebrates 56 (1) on pages 120-122, DOI: 10.5733/afin.056.0109, http://zenodo.org/record/7661863