Caecum lozoueti, Walter & Renda, 2024

Walter, Angelo Vannozzi & Renda, Walter, 2024, Sampling the depth: New data on the Caecidae (Mollusca, Gastropoda) from northeastern Papua New Guinea, Zoosystema 46 (14), pp. 327-347 : 340-342

Caecum lozoueti n. sp.

( Fig. 7 D-I)

urn:lsid:zoobank.org:act:E0AE9D31-298F-4E9F-9C16-F66A66E51CBE

Caecum cf. glabellum Carpenter in Adams, 1868: 365. — Pizzini et al. 2013: 24-25, fig. 11N-P.

TYPE MATERIAL. — Holotype. Loyalty • lv (length 1.77 mm, Fig. 7 F-I); Baie du Santal, récif Shelter , LIFOU 2000 Stn 1432; 20°53.5’S, 167°02.7’E; 12-32 m depth; 21.IX.2000; MNHN-IM-2012-37972 . Paratype. Loyalty • 1 sh; Lifou , Santal Bay , in front of Peng, LIFOU 2000 Stn 1412; 20°54.2’S, 167°07.4’E; 2-5 m depth; 14.XI.2000; MNHN-IM-2012-37974 .

TYPE LOCALITY. — Pacific Ocean, Loyalty, Baie du Santal, Récif Shelter; 20°53.5’S, 167°02.7’E; 12-32 m depth.

OTHER MATERIAL EXAMINED. — Papua New Guinea • 1 sh; Sek Island ; PAPUA NIUGINI Stn CP3957; 5°05’S, 145°51’E; 452- 504 m depth; 28.XI.2012; MNHN-IM-2022-2398 .

DISTRIBUTION. — Known from northeastern PNG and Loyalty ( Pizzini et al. 2013).

ETYMOLOGY. — The species is dedicated to Pierre Lozouet (MNHN) for his prompt help provided with the samples of this species preserved in the MNHN.

DESCRIPTION

Shell small for the genus, colourless, semitransparent. Protoconch unknown.Teleoconch tubular, arched, almost smooth. Early teleoconch unknown. Adult shell subcylindrical, with coarse longitudinal striation. Microsculpture of fine, worm-like grooves, visible close to the aperture. Aperture without a clear swelling, ending in a fine reflected lip. Septum low dome-shaped without mucro, smooth, slightly recessed below the cutting plane. Periostracum thick, opaque, showing a longitudinal striation. Operculum circular, thin, flat. Soft parts unknown. Holotype: length 1.77 mm, max diam 0.36 mm, min diam 0.29 mm.

REMARKS

This small species was tentatively classified as Caecum glabellum by Pizzini et al. (2013) due to the small size and the simple, dome-shaped septum. However, the presence of a coarse longitudinal striation and of a worm-like microsculpture as well, excludes the possibility that it might represent Caecum glabellum , which is today considered as a nomen dubium due to the lack of type material and of Japanese specimens fitting Carpenter’s description ( Vannozzi 2022a).

The finding of a further specimen from PNG let us recognise the characters of this species. However, the specimens from Loyalty, already in the MNHN collection, were preferred as type specimens due to the better condition.

Caecum crystallinum de Folin, 1880 , described from Hawaii from a single fragmentary specimen without apex, shows a similar microsculpture. However, in this species the tube is slenderer and expands before the aperture. Study of Hawaiian topotypical specimens is necessary in order to determine the actual shape of the septum in de Folin’s species.

The new species superficially resembles Caecum succineum due to the small size and the low dome-shaped septum without mucro. However, C. succineum shows a few rings and a small but clear swelling before the aperture. Furthermore, it shows a completely different microsculpture, i.e., collabral rather than longitudinal.

Figures

FIG. 7. — Caecum Fleming, 1813 new species: A-C, Caecum temporale n. sp.: A, B, holotype MNHN-IM-2012-37957; C, specimen from Stn DW4464 MNHN- IM-2000-38950; D-I, Caecum lozoueti n. sp.: D, E, specimen from Stn CP3957 MNHN-IM-2022-2398; F-I, holotype MNHN-IM-2012-37972. Scale bars: A, B, D-G, 1 mm; C, 0.5 mm, details not to scale. Image courtesy of D. Geiger (A), M. Hennion (B, G) and A. Le Goff (F, H, I).