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Caecum sp. (Figs 2N; 4E; 5D) MATERIAL EXAMINED. — Mayotte • 1 dd; Mozambique Channel, W Mayotte, BIOMAGLO Stn DW4847; 12°41’S, 44°57’E; 738- 763 m depth; 30.I.2017; MNHN. DESCRIPTION Shell of average size for the genus, smooth, colourless, semitransparent, iridescent. Tube cylindrical, not twisted and gradually tapering toward the apex. Surface smooth crossed by fine growth lines only. Macula absent. Aperture preceded by a strong varix-like swelling, somewhat inclined toward the left side. Septum narrow, dome shaped, slightly asymmetrical in dorso-ventral direction but without any visible mucro. Length 2.4 mm. REMARKS This single specimen recalls both Caecum biomaglo n. sp. and C. iricolor n. sp. due to the smooth, iridescent tube with similar size. However, it is clearly distinguished by the more protruding septum, the stronger varix-like swelling and the smooth surface without longitudinal microsculpture.Additional material is necessary to clarify the identity of this specimen. A loose operculum was found in the capsule containing this sample, possibly belonging to this specimen. In fact, this operculum is corneous, circular, thin, flat on both sides and with compatible size, whereas the specimens of other species found in the same station are very worn, as C. hyalinum Vannozzi, 2022, or much larger, as Mauroceras kajiyamai, or are known to have a differently shaped operculum, i.e., thick with stepped profile in C. sepimentum or hat-shaped in C. cooki (Pizzini et al. 2013: fig. 19). |
