Caecum cf. clathratum Carpenter, 1857

Egger, Christina, Neusser, Timea P., Norenburg, Jon, Leasi, Francesca, Buge, Barbara, Vannozzi, Angelo, Cunha, Regina L., Cox, Cymon J. & Joerger, Katharina M., 2020, Uncovering the shell game with barcodes: diversity of meiofaunal Caecidae snails (Truncatelloidea, Caenogastropoda) from Central America, ZooKeys 968, pp. 1-42 : 1

Caecum cf. clathratum Carpenter, 1857

Caecum clathratum Carpenter, 1857 in Carpenter (1855-1857): 322, pl. 34, figs 269, 1528. Type locality: Mazatlán [Mexico].

Material examined.

French Antilles • 1 (Fig. 6R-U ); Guadeloupe; 16.2235, -61.5305; depth 1 m; 2 May 2012; MNHN KARUBENTHOS exped.; Stat. GM01; GenBank: MT704294, MT731710; MNHN-IM-2019-17.

Shell morphology.

Large, thick shell (3.0 mm length and 0.8 mm width) with and even curvature (Fig. 6R ). Color opaque yellow brownish, entire specimen covered in dense dark periostracum. Septum triangular merged with pointed mucro (Fig. 6T ). Aperture oblique and constricted. Shell with 21 strong and protruding sharp ribs and deep interspaces narrowing at aperture (Fig. 6R, S ). Ribs and interspaces smooth without microsculptural diagnostic features (Fig. 6U ).

Remarks.

The specimen corresponds to C. clathratum , which differs from other ribbed Caecum species by its exceptional size, golden color and lack of microsculpture (compare with Lightfoot 1993a: 15, fig. 1 and a syntype collected by Carpenter available through the online catalogue of the Natural History Museum London catalogue number 1857.6.4.1528). However, the specimen is described and known only from the Eastern Pacific. Our herein investigated specimen from the Atlantic might thus present a (morphologically cryptic) sister species new to science, which potentially originated when populations were separated via the formation of the Isthmus of Panama. But molecular data of specimens collected from the Eastern Pacific is required to confirm the molecular identity or justify the description of a new species.

Figures

Figure 6. A-E Caecum heptagonum A specimen USNM 1618866 juvenile specimen with larval shell still attached B-E specimen ZSM-Mol- 20200030, juvenile specimen already resembling closely the adult form B light microscopic picture C SEM scan D close-up of mucro and E microsculpture F-I C. cooperi, specimen MNHN-IM- 2019 - 32 F light microscopic picture G SEM scan H close-up of mucro and I microsculpture whole specimen and close-up of mucro and microsculpture J-M C. debile, specimen MNHN-IM- 2019 - 27 J light microscopic picture K SEM scan L close-up of mucro and M microsculpture N-Q C. striatum, specimen ZSM-Mol- 20100322 N light microscopic picture O SEM scan P close-up of mucro and Q microsculpture R-U C. clathratum, specimen MNHN-IM- 2019 - 17 R light microscopic picture S SEM scan T close-up of mucro and U microsculpture. Scale bars: 10 µm (D, E, I, Q); 20 µm (H, M, P, U); 100 µm (A, B, C, L, N, O, T); 200 µm (F, G, J, K whole specimen); 300 µm (R, S).