Caecum inhacaense Albano & Pizzini, 2011

Vannozzi, Angelo, Pizzini, Mauro & Raines, Bret, 2015, Revision of South African Caecidae (Mollusca: Gastropoda), African Invertebrates 56 (1), pp. 99-99 : 114-115

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.7675546
persistent identifier	https://treatment.plazi.org/id/D6171E5C-FFE8-FFA5-2793-B89C802A3391
treatment provided by	Felipe
scientific name	Caecum inhacaense Albano & Pizzini, 2011
status

Treatment

Caecum inhacaense Albano & Pizzini, 2011 View in CoL

Figs 12A–C View Fig , 13 View Fig , 22K View Fig , 23K View Fig , 24G View Fig , 26A, B View Fig Caecum inhacaense: Albano & Pizzini 2011: 5 , 6, fig. 3A–C, E.

Type locality: MOZAMBIQUE: Ilha de Inhaca, Barreira Vermelha.

Type material examined: MOZAMBIQUE: holotype ( MZB 15000 View Materials ) .

Material examined: SOUTH AFRICA: Eastern Cape: 10 sh, Mzamba, near Natal border, vii.1976 ( JPM 2119 ); 1 lv, Mtentu R. Mouth, iv.1982 ( JPM 2414 ) ; KwaZulu-Natal: 1 sh, Aliwal Shoal, off Umkomaas area , - 27 m, SCUBA, i.1988 ( JPM) ; 2 sh (1 juv), Stn ZO 4, off Cape St. Lucia (28°31.8'S 32°26.9'E), - 76–80 m, coarse sand with mud, dredged R.V. Meiring Naudé, NMDP, 12.vi.1988 ( NMSA W9665 View Materials ) GoogleMaps .

Doubtful: SOUTH AFRICA: Western Cape: 1 sh, Knysna, Gericke Point, Sedgefield ( NMSA W9679 View Materials ) ; Eastern Cape: 1 sh, Algoa Bay, St. Croix I., East , - 50–60 ft, coarse sand, dived A. Connell, don. C.S.I.R. Water Res. 1977 ( NMSA A6770 View Materials ) ; 1 sh, Mzamba, beachdrift, leg. R. Kilburn & D. Herbert 12– 30.5.1986 ( NMSA W9664 View Materials ) .

Comparative material examined: C. incisum sp. n.

Original description: “Tube cylindrical, smooth, crossed only by fine growth striation. Septum mucronate, turned to right side by about 30° and protruding over the cutting plane. Mucro has the form of a small flattened ball, almost obsolete in juvenile specimens. Dorsal margin of mucro strongly convex, while its ventral margin slightly S-shaped and inflated near the cutting plane. Aperture circular, weakly ringed and slightly contracted. Juveniles have more slender shell, and aperture lip thin and fragile. Colour whitish. Operculum and soft parts morphology unknown.

Holotype dimensions: length 1.4 mm, diameter 0.3 mm.”

Additional description: Tube cylindrical, colourless, whitish in beached specimens, the last portion bent toward the ventral side. No sculpture. Aperture slightly flaring and oblique. Surface with only oblique growth lines. Septum opaque, dome-shaped, variably protruding. Mucro illdefined, placed on the right side, typically higher than the septum, dorsally protruding with a resulting concave outline just above the cutting plane. Macula white, small, roundish to chevron-shaped, located in the middle of the ventral side of the tube, slightly displaced toward the left side ( Fig. 24G View Fig ). Periostracum light brown, somewhat glossy, persistent.

Length: 1.2–1.6 mm.

Distribution: Originally described from south of Mozambique, its distribution is herein extended to the eastern coast of South Africa up to the Mtentu River ( Fig. 13 View Fig ). Its occurrence on the southern coast needs confirmation.

Remarks: Caecum inhacaense resembles the sympatric C. incisum sp. n. as regards to the general proportions, but it can be distinguished by the presence of a white macula, the lack of incised collabral grooves, the presence of a slight apertural swelling and the mucro that forms a lower angle with respect to the ventral-dorsal direction.

Caecum inhacaense is a rather elusive species due to the lack of striking characters. A careful examination of South African specimens revealed that the bending of the last quarter of the tube and the shape of the mucro are useful characters. In particular, the mucro is neither nail- nor ear-like as in other species with similar appearance, but has a convex outline, shaped like a flattened ball that protrudes dorsally, leaving a concave region just above the cutting plane. Also the presence of a small, white macula is a useful character.