Caecum austrafricanum, Vannozzi & Pizzini & Raines, 2015

Vannozzi, Angelo, Pizzini, Mauro & Raines, Bret, 2015, Revision of South African Caecidae (Mollusca: Gastropoda), African Invertebrates 56 (1), pp. 99-99 : 105-107

publication ID	https://doi.org/ 10.5733/afin.056.0109
publication LSID	lsid:zoobank.org:pub:2A9621F0-009E-4A25-A093-DD322B9EC120
DOI	https://doi.org/10.5281/zenodo.7675538
persistent identifier	https://treatment.plazi.org/id/53B1488C-8276-433D-9265-A3ABAD002B19
taxon LSID	lsid:zoobank.org:act:53B1488C-8276-433D-9265-A3ABAD002B19
treatment provided by	Felipe
scientific name	Caecum austrafricanum
status	sp. nov.

Treatment

Caecum austrafricanum View in CoL sp. n.

Figs 4A–H View Fig , 7 View Fig , 22F–H View Fig , 23F–H View Fig , 24A View Fig , 25N, O View Fig

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 View Fig , 22F View Fig , 23F View Fig ): 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 View Materials /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 View Materials /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 View Materials /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 View Materials /T3353); 6 sh (1 juv), Algoa Bay , Humewood sand, don. F. Graeve , v.1977 ( NMSA A5589 View Materials /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 View Materials /T3878); 1 sh, Aliwal Shoal, off Scottburgh, - 25–27 m, sand and reef debris ( NMSA S7078 View Materials /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 View Materials ) ; 1 sh, Knysna , Gericke Point, Sedgefield ( NMSA W9671 View Materials ) ; Eastern Cape: 3 lv and 5 sh, Fish R. mouth, south side ( NMSA B4185 View Materials ) ; 74 lv, Algoa Bay , off Cape Recife, - 25 m, debris from bryozoan colony, dived B. Hayes, xii.1992 ( NMSA W9685 View Materials ); 17 sh, Port Alfred , leg. J. Hutt (J. Hutt colln, ex Albany Museum, 1980, NMSA E1666 View Materials ) .

Comparative material examined: C. variegatum de Folin, 1867 , syntype (MNHN-IM-2000-25783, Fig. 21A–D View Fig ); 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 View Fig ).

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 View Fig ). 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 View Fig , 23F, G View Fig ).

Caecum austrafricanum resembles C. macrum van der Linden & Moolenbeek, 2000 ( Fig. 25R View Fig ) 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 View Fig ).