Caecum sepimentum de Folin, 1868

Vannozzi, Angelo, 2023, The Caecidae from BIOMAGLO Expedition in the Mayotte-Glorieuses area (Mollusca, Gastropoda), Zoosystema 45 (12), pp. 421-434 : 424

Caecum sepimentum de Folin, 1868

( Fig. 2 A-C)

Caecum sepimentum de Folin, 1868: 84 , pl. 6, fig. 7. — Vannozzi 2019b: 73, fig. 7E and synonymy therein.

† Caecum afrum Selli, 1974: 308 , pl. 16, figs 11-13.

TYPE MATERIAL. — Lectotype. Mauritius • dd; Mauritius ; MNHN-IM-2000-24907 selected by Pizzini et al. (2013: 5, fig. 8D).

Paralectotypes. Mauritius • 20 dd; same data as for lectotype; MNHN-IM-2000-24908 .

TYPE LOCALITY. — Indian Ocean , Mauritius.

MATERIAL EXAMINED — Îles Éparses • 5 Dd; Mozambique Channel, Banc Du Geyser, Biomaglo Stn Dw 4789; 12°22’S, 46°25’E; 340-342 m depth; 22.I.2017; MNHN • 5 dd worn; Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4800; 11°27’S, 47°19’E; 240-255 m depth; 24.I.2017; MNHN • 14 dd (1 juv) worn; Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4801; 11°27’S, 47°19’E; 385-410 m depth; 24.I.2017; MNHN • 32 dd (9 juv, 1 growth stage, 2 fragm) mostly worn; Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4807; 11°30’S, 47°28’E; 97-124 m depth; 25.I.2017; MNHN • 62 dd (9 juv); Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4808; 11°30’S, 47°28’E; 219-224 m depth; 25.I.2017; MNHN • 1 dd; Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4814; 11°30’S, 47°29’E; 694-733 m depth; 25.I.2017; MNHN • 3 dd worn; Mozambique Channel, Glorieuses, BIOMAGLO Stn DW 4818; 11°37’S, 47°20’E; 797-816 m depth; 26.I.2017; MNHN .

Mayotte • 42 dd (1 juv); Mozambique Channel, S Mayotte, BIOMAGLO Stn DW 4820; 13°05’S, 45°06’E; 295-336 m depth; 27.I.2017; MNHN • 10 dd; Mozambique Channel, S Mayotte, BIOMAGLO Stn DW 4826; 13°05’S, 45°07’E; 489-496 m depth; 27.I.2017; MNHN • 4 dd; Mozambique Channel, W Mayotte, BIOMAGLO Stn DW 4846; 12°41’S, 44°58’E; 439-502 m depth; 30.I.2017; MNHN • 11 dd (1 juv); Mozambique Channel, W Mayotte, BIOMAGLO Stn DW 4847; 12°41’S, 44°57’E; 738-763 m depth; 30.I.2017; MNHN • 16 dd (1 juv); Mozambique Channel, NW Mayotte, BIOMAGLO Stn DW 4848; 12°35’S, 44°55’E; 399- 402 m depth; 30.I.2017; MNHN • 5 dd mostly worn; Mozambique Channel, SW Mayotte, BIOMAGLO Stn DW 4851; 13°01’S, 44°57’E; 660-664 m depth; 03.II.2017; MNHN • 5 dd; Mozambique Channel, SW Mayotte, BIOMAGLO Stn DW 4853; 13°00’S, 44°56’E; 665-669 m depth; 03.II.2017; MNHN • 18 dd (6 juv); Mozambique Channel, W Mayotte, BIOMAGLO Stn DW 4854; 12°56’S, 44°58’E; 455-465 m depth; 04.II.2017; MNHN • 11 dd (2 juv, 1 growth stage) worn; Mozambique Channel, NW Mayotte, BIOMAGLO Stn DW 4860; 12°31’S, 44°55’E; 486-646 m depth; 05.II.2017; MNHN • 7 dd worn; Mozambique Channel, SE Mayotte, BIOMAGLO Stn DW 4864; 12°56’S, 45°15’E; 455-487 m depth; 07.II.2017; MNHN • 20 dd (1 juv) worn; Mozambique Channel, NE Mayotte, BIOMAGLO Stn DW 4871; 12°44’S, 45°19’E; 462- 486 m depth; 08.II.2017; MNHN .

Comoros • 11 dd (3 juv, 3 fragm); Mozambique Channel, SE Moheli, BIOMAGLO Stn DW 4836; 12°25.2’S, 43°55.9’E; 82-88 m depth; 28.I.2017; MNHN • 1 dd (juv); Mozambique Channel, SW Moheli, BIOMAGLO Stn DW 4841; 12°23’S, 43°33’E; 154-333 m depth; 29.I.2017; MNHN • 1 dd (fragm) worn; Mozambique Channel, SW Moheli, BIOMAGLO Stn DW 4842; 12°23’S, 43°33’E; 388- 420 m depth; 29.I.2017; MNHN • 1 dd; Mozambique Channel, SE Moheli, BIOMAGLO Stn DW 4843; 12°28’S, 43°54’E; 509- 530 m depth; 29.I.2017; MNHN .

DISTRIBUTION. — Whole Indo-West Pacific. From the east coast of Africa (Red Sea to eastern South Africa) to Maldives, Papua New Guinea, Philippines, Japan, Australia, New Caledonia, French Polynesia, Hawaii ( Hedley 1903; Kay 1979; Lightfoot 1992a; Hasegawa 2000; Albano & Pizzini 2011; Pizzini & Raines 2011; Pizzini et al. 2013; Vannozzi et al. 2015; Vannozzi 2017, 2019b; Blatterer 2019; unpublished data). Allochthonous to the Mediterranean Sea ( Pagli 2009; Ovalis & Mifsud 2014).

DIAGNOSIS. — Shell of average size for the genus. Tube subcylindrical, evenly arched. Sculpture of about 21 strong rings with a somewhat subtriangular profile. Aperture preceded by a swelling, ending with several concentric small rings. Microsculpture of fine longitudinal threads. Septum almost flat without mucro, lying below the cutting plane. Periostracum brownish. Colourless or creamy, often with darker blotches. Juveniles showing a conical and more curved tube. Transition to the adult stage smooth. Protoconch multispiral with about 1.9 whorls. Operculum circular, terraced. Length 2.5 mm.

REMARKS

Caecum sepimentum is by far the commonest caecid in the entire Indo-West Pacific, and represents the vast majority of the caecids collected during the BIOMAGLO Expedition, occurring in almost all stations.

Figures

FIG. 2. — Side and ventral views of Caecum Fleming, 1813 species from BIOMAGLO Expedition: A-C, C. sepimentum de Folin, 1868 from Stn DW4848; A, B, specimens with preserved colour pattern; C, juv.; D, C. succineum de Folin, 1880 from Stn DW4854; E-H, C. iricolor n. sp.; E, F, holotype MNHN- IM-2000-38696, length 2.33 mm; G, H, paratype MNHN-IM-2000-38697 from type locality; I-M, C. biomaglo n. sp.; I, J, holotype MNHN-IM-2000-38700, length 2.46 mm; K, L, paratype MNHN-IM-2000-38701 from type locality; M, paratype from Stn DW4854 MNHN-IM-2000-38702; N, Caecum sp. from Stn DW4847, length 2.4 mm. Scale bar: 1 mm.