Caecum morgan sp. n.

Figs 2A–F, 3, 22D, E, 23D, E, 26J, K

Etymology: Derived from the type locality (Cape Morgan) and used as a noun in apposition.

Description:Tube small, subcylindrical, proportionally thick, whitish, smooth.Aperture slightly oblique toward the ventral side, showing a well-developed swelling followed by a contraction and finally by a very small ring. Surface smooth, dull, without microsculpture. Septum opaque, slightly protruding over the cutting plane, with a sharp, nail-like mucro directed toward the right side, giving a dome-shaped outline to the septum when viewed from the side. Early stages and operculum unknown.

Length: 1.6–1.8 mm.

Type locality: SOUTH AFRICA: Eastern Cape: Agulhas Bank, off Cape Morgan Lighthouse, - 100 m.

Holotype (Figs 2A–C, 22D, 23D): SOUTH AFRICA: Eastern Cape: sh, Agulhas Bank, off Cape Morgan Lighthouse, - 100 m, broken coral + shell, don. A. Connell, 1977, (NMSA B7132 / T3377), length 1.66 mm, min. diam. (posterior end) 0.22 mm, diam. in the middle of the tube 0.30 mm, max. diam. (apertural end) 0.34 mm.

Paratypes: 6 sh, same data as holotype (NMSA W9676 / T3378) .

Comparative material examined: C. campanulatum Raines & Pizzini, 2005, holotype (LACM 3027); C. chinense de Folin, 1868, lectotype (MNHN-IM-2000-24905); C.dakuwaqa Pizzini, Raines & Vannozzi, 2013, holotype (MNHN-IM-2000-24843); C. subquadratum Carpenter, 1859, lectotype (NHMUK 1858.12.9.13, Fig. 21E); C. fijiense Pizzini, Raines & Vannozzi, 2013, holotype (MNHN-IM-2000-24857).

Distribution: Currently known only from the type locality, Cape Morgan, north of East London (Fig. 3).

Remarks: Caecum morgan sp. n. strongly resembles C. subquadratum due to the lack of both sculpture and microsculpture, as well as a similar shape of the mucro. It can however be separated by the distinctly subcylindrical and more curved shape of the tube, and by the presence of a conspicuous swelling above the aperture, barely visible in C. subquadratum . In C. morgan sp. n. the septum is only somewhat emerging above the cutting plane. Conversely, in C. subquadratum the septum is more protruding, on the whole giving the mamillate-ungulate appearance pointed out by Carpenter (1859). Caecum morgan sp. n. resembles C. gofasi Pizzini & Nofroni, 2001 in general aspect, but the latter has a dorsal spatulate mucro and shows a distinct worm-like microsculpture absent in the new species. Moreover, C. morgan sp. n. is also similar to C. campanulatum Raines & Pizzini 2005, C. dakuwaqa, and C. fijiense (both Pizzini, Raines & Vannozzi, 2013), having the same bell-shaped aperture, but in these species the septum is domeshaped without any mucro. Additionally, C. morgan sp. n. differs from C. dakuwaqa by the lack of the exasperate torsion of the tube occurring in the latter. Caecum morgan is also similar to C. musorstomi Pizzini, Raines & Vannozzi, 2013, from which it can be separated by the smooth surface without sculpture, and microsculpture and by a different orientation and shape of the mucro.