Caecum austrafricanum Vannozzi & Pizzini & Raines 2015, sp. n.
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 austrafricanum

description: Caecum austrafricanum sp. n.
Figs 4A–H, 7, 22F–H, 23F–H, 24A, 25N, O
Etymology: From Latin name auster (the south) and the adjective africanus (African), meaning South African.
Description: Tube subcylindrical, slender, with a slight dextral torsion, rather straight in the adapical portion, more or less curved in the abapical half. Tube smooth, somewhat glossy, colourless. Aperture oblique with a rather strong swelling, preceded by a white band. Surface with only oblique growth lines. Septum opaque, protruding, with a variable outline, often from flat to S­shaped, more rarely convex, with a dorsal naillike mucro, somewhat rotated toward the right side, generally more protruding than the septum. Macula large with a frosted appearance, more or less symmetrical, elongated, placed in the middle of the ventral side, posteriorly bilobed, anteriorly narrower and fading. Juveniles rather different from adults, distinctly conical and showing a clear dextral torsion. Larval stage not determined with certainty, probably with a multispiral protoconch. Periostracum light brown. Operculum, corneous, circular, multispiral, composed by a central nucleus surrounded by a tight spiral of about 4 whorls. External side slightly concave, internal side with a raised nucleus.
Length: 1.7–2.9 mm.
Type locality: SOUTH AFRICA: Eastern Cape: Algoa Bay.
Holotype (Figs 4A–C, 22F, 23F): lv, SOUTH AFRICA: Eastern Cape: Algoa Bay, vi.1976 (W9655/T3349), length 2.11 mm, min. diam. (posterior end) 0.32 mm, diam. in the middle of the tube 0.41 mm, max. diam. (apertural end) 0.44 mm.
Paratypes: SOUTH AFRICA: Western Cape: 18 lv and 166 sh (9 juv), Knysna, Gericke Point, Sedgefield (NMSA W9659 /T3352); 18 lv and 245 sh (23 juv), Walker’s Point, W of Knysna, leg. J.P. Marais iii.1991 (NMSAW9656/T3351); 1 sh (worn), Cape Overberg, Onrus R., ± 5 km W of Hermanus, in sand under rock in sheltered rockpool (NMSA S2626 /T3879); 1 sh, Hermanus (between False Bay and Cape Agulhas), v.1990 (JPM); 1 lv and 24 sh, Walker’s Bay, W of Knysna, iii.1991 (JPM); 3 sh, False Bay, Miller’s Point, purch. Mrs C.M. Connolly i.1974 (NMSA A1879 /T3877); Eastern Cape: 5 lv and 47 sh (1 with two attached stages), same data as holotype (JPM); 4 lv (with opercula in small glass vials), Algoa Bay, off Cape Recife, - 25 m, debris from bryozoan colony, dived B. Hayes, xii.1992 (NMSA V115 /T3353); 6 sh (1 juv), Algoa Bay, Humewood sand, don. F. Graeve, v.1977 (NMSA A5589 /T3350); 2 lv and 22 sh, Fish R. mouth (between Port Alfred and East London), iv.1978 (JPM 2117); KwaZulu-Natal: 1 lv and 1 sh, Aliwal Shoal, off Umkomaas, - 27 m, silt from between rocks, dived G. Smith, don. J.P. Marais iii.1988 (NMSA E1670 /T3878); 1 sh, Aliwal Shoal, off Scottburgh, - 25–27 m, sand and reef debris (NMSA S7078 /T3880).
Additional material examined: SOUTH AFRICA: Western Cape: 1 sh, Witsand, Brede R. mouth, St. Sebastian Bay, beachdrift, leg. C.D. Quickelberge 2.ix.1982 (NMSA E2395); 1 sh, Knysna, Gericke Point, Sedgefield (NMSA W9671); Eastern Cape: 3 lv and 5 sh, Fish R. mouth, south side (NMSA B4185); 74 lv, Algoa Bay, off Cape Recife, - 25 m, debris from bryozoan colony, dived B. Hayes, xii.1992 (NMSA W9685); 17 sh, Port Alfred, leg. J. Hutt (J. Hutt colln, ex Albany Museum, 1980, NMSA E1666).
Comparative material examined: C. variegatum de Folin, 1867, syntype (MNHN-IM-2000-25783, Fig. 21A–D); C. macrum van der Linden & Moolenbeek, 2000; SENEGAL: 2 sh, Charbonnier, petite épave, - 34 m, fond sable coquiller légerement vaseux, leg. J. Pelorce (MP); 1 sh, Somone, - 7 m, sable sur rochers plats avec curvettes sable, leg. J. Pelorce (MP).
Distribution: Southern and eastern coasts of South Africa, from False Bay to Aliwal Shoal, south of Durban (Fig. 7).
Remarks: This species is rather variable in terms of dimensions and curvature of the tube, which is, however, always straighter in the middle portion. The most similar species to Caecum austrafricanum is C. variegatum de Folin, 1867 (Fig. 21A–D). Caecum variegatum was originally described by de Folin from Hong Kong and recently reported by Hughes (1985) for the same locality, while no other finding is reported in the literature.This species seems to be absent from Australia as well (unpublished data). The main differences concern the absence of apertural swelling in C. variegatum and the shape of the mucro, which is narrow and spatuliform in C. variegatum, while in C. austrafricanum it is broad and not distinct from the septum when observed in ventral view (Figs 21D, 23F, G).
Caecum austrafricanum resembles C. macrum van der Linden & Moolenbeek, 2000 (Fig. 25R) described from western Africa, from which it can be distinguished by the slenderer and thicker tube, the aperture provided with a well-developed swelling not observed in C. macrum and by the different shape of the septum. Moreover, the macula in C. macrum is different, being shorter and heart-shaped (Fig. 24A, H).
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 105-107, DOI: 10.5733/afin.056.0109, http://zenodo.org/record/7661863