Caecum debile Verrill & Bush, 1900

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 debile Verrill & Bush, 1900

Caecum debile Verrill & Bush, 1900: 538. Type locality: Bermuda, Ship Channel and Bailey Bay, in 12 to 40 feet.

Material examined.

French Antilles • 1 (Fig. 6J-M ); Guadeloupe; 16.3558, -61.5965; depth 2 m; 24 May 2012; MNHN KARUBENTHOS exped.; Stat. GS32 GenBank: MT704295, MT731711; MNHN-IM-2019-27a. • 1; same collection data as for preceding; GenBank: MT704296, MT731712; MNHN-IM-2019-27b.

Shell morphology.

Color whitish, slightly translucent. Specimens about 2.0 mm long, 0.5 mm wide. Tube of adult specimen 2.1 mm long, 0.5 mm wide. Tube evenly curved and evenly wide over entire length (Fig. 6J, K ). Septum separated by sharp rim from tube and hemispherical without protruding mucro (Fig. 6L ). Aperture with protruding ring. Shell structured by longitudinal striae clearly observable via LM. Microsculpture of fine wavy striation (Fig. 6M ).

Remarks.

The present specimens were assigned to C. debile based on the characteristic microsculpture (see Absalão and Gomes 2001). Morphologically, C. debile might present a synonym of C. infimum , de Folin, 1867 (de Folin and Périer 1867: 26, pl.3, fig. 2) but, in awareness of cryptic species we refrain from synonymizing until C. infimum from the type locality is available for molecular analyses. Some species delineation analyses, separate C. debile into two independent species (Fig. 4 ), which might indicate a putative speciation, but more data on the genetic variability is needed to exclude the presence of an artefact in analyses.

Figures

Figure 4. Molecular based species delimitation of Central American Caecidae. Guide tree used for PTP and bPTP based on the optimal likelihood tree of the concatenated three-marker dataset. Color codes indicate our preliminary species hypothesis derived from the phylogenetic tree. Color bars reflect the species delimitation suggested by the four consulted species delimitation programs (including ML and Bayesian implementation for PTP and single and multiple threshold for GMYC). Bars are missing where no sequence data obtained.

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).