Caecum regulare Carpenter, 1858

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 regulare Carpenter, 1858

Caecum regulare Carpenter, 1858 in Carpenter (1858-1859): 428-429, pl. 69. Type locality: W. Indies (Woodward) [Caribbean].

Material examined.

Panama • 1, juv.; Bocas del Toro; 9.2141, -81.9318; depth 8.5 m; 5 Jun 2010; USNM BRS2010 exped.; Stat. BRS108; DNA voucher; GenBank: MT727050, MT731690; USNM 1618883. Belize • 1, juv. (Fig. 7H-K ); Carrie Bow Cay; 16.7911, -88.0761; depth 15 m; 24 Jan 2010; USNM Belize2010 exped.; Stat. CBC22; DNA voucher; DNA bank: r462p17f2t91; GenBank: MT704280, MT731708; ZSM-Mol-20100321. • 1, juv.; same collection data as for preceding; ZSM-Mol-20200114.

Shell morphology.

Shell translucent, color white to yellowish (Fig. 7H ). Size 1.0 mm long, 0.4 mm wide. Tube curved regularly in moderate angle, tapering towards posterior, widening at aperture, thick lip (10 µm) (Fig. 7H, I ). Septum slightly domed. Mucro slender and sharply pointed (Fig. 7J , but tip broken in specimen ZSM-Mol-20100321). Sculpture consists of 32 marked and rounded transverse ribs, narrowing towards septum, with narrow deep interspaces (Fig. 7I ). Microsculpture shows longitudinal fusiform lobes covering the ribs (Fig. 7K ).

Remarks.

We identified the specimens as C. regulare by referring to the drawings of Carpenter’s original description ( Carpenter 1857; 1858-1859), the syntype material from the Natural History Museum, London, UK accessed through the online catalogue (catalogue numbers 1858.12.9.19, 1858.12.9.20, 1858.12.9.21) and the re-description of Moore (1972): 888, fig. 7. The conspicuous widening of the shell very close to the aperture in our specimen investigated can be interpreted as a character of a sub-adult growth stage ( Bandel 1996), thus not contradicting the assignment to C. regulare . A literature survey suggests at least one putative synonym of C. regulare , resp. Caecum planum , de Folin, 1874 ( de Folin and Périer 1875: 277, t. 2, pl.10, figs 8, 9). However, the geographical distribution differs ( C. regulare was originally described from the Caribbean and C. planum from Brazil), and there are no evident diagnostic differences to C. regulare. Hence, molecular data is needed for clarification. Further data also is needed for the complementary gene sequences (16S rRNA and COI) for the two investigated specimens. We consequently attribute the split of our two investigated specimens into distinct molecular species to missing data in our analyses.

Figures

Figure 7. A-F Caecum pulchellum A, C, E, F specimen ZSM-Mol- 20090485 B, D juvenile specimen ZSM-Mol- 20200118 A, B light microscopic pictures C, D SEM scans E close-up of mucro and F microsculpture H-K C. donmoorei, specimen USNM 1618844 H-K C. regulare, specimen ZSM-Mol- 20100321, juvenile H light microscopic picture I SEM scans J close-up of mucro and K microsculpture L-T C. cf. teres and C. cf. strangulatum L specimen ZSM-Mol- 20200033, juvenile specimen with larval shell still attached M, N, Q, S specimen ZSM-Mol- 20200032, juvenile M light microscopic picture N SEM scan Q close-up of mucro and S microsculpture O, P, R, T C. cf. strangulatum, specimen ZSM-Mol- 20200038, juvenile O light microscopic picture P SEM scan R close-up of mucro and T microsculpture U-X C. cf. semilaeve, specimen ZSM-Mol- 20200034 U Light microscopic picture V SEM scan W close-up of mucro and X microsculpture. Scale bars: 10 µm (F, S, T, W, X); 20 µm (J, K, Q, R); 50 µm (E); 100 µm (H, I, L-P, U, V); 200 µm (A-D).