Meioceras cubitatum de Folin, 1868

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

Meioceras cubitatum de Folin, 1868

Meioceras cubitatum de Folin, 1868 in De Folin and Périer (1867-1871): 50, pl. 5, fig. 4. Type locality: Baie de Bahia [Bahia Bay, Brazil].

Caecum cubitatum (de Folin, 1868): 19; Meioceras tenerum de Folin, 1869: 24.

Material examined.

Belize • 1 (Fig. 5E ); Carrie Bow Cay; 16.8021, -88.0767; depth 31 m; 22 Jan 2010; USNM Belize 2010 exped.; Stat. CBC15; DNA voucher; GenBank: MT727067, MT731709; USNM 1618851.

Shell morphology.

Shell opaque white and solid. Mottled grayish pattern over whole shell, two rows of distinct brown dashes along dorsal side (Fig. 5E ). Specimen approx. 2 mm. Tube not evenly curved but appears bulbous and is rounded strongly towards aperture, decreasing towards mucro. Mucro thin and sharp.

Remarks.

Our molecular phylogenetic results delimited M. cubitatum as a separate species, despite similarities to M. nitidum in its bulbous shell shape and pattern. Surprisingly, our molecular analyses do not retrieve these morphologically similar Meioceras species as a monophyletic entity but suggest independent origin within Caecum . Morphological differences towards M. nitidum (characterized above) are a more slender shell with more pronounced curvature towards the anterior end and the opaque color of the present individual. We assigned the specimen to Meioceras cubitatum sensu de Folin, 1869 from Bahia, Brazil ( dos Santos Gomes and Absalão 1996: 523, figs 12-15; De Folin and Périer 1867: pl. 5, fig. 4; Redfern 2001: fig. 178A, B) = Meioceras cornucopiae Carpenter, 1859 (from the West Indies, exact type locality unknown) sensu Lima et al. (2015: 3, fig. 7). Nevertheless, this Meioceras species likely should also be reallocated to the genus Caecum based on the results of our phylogenetic analyses.

Figures

Figure 5. A-D Meioceras nitidum, specimen MNHN-IM- 2013 - 72087 A light microscopic picture B SEM scan C SEM close-up of mucro and D microsculpture E M. cubitatum, specimen USNM 1618851 F, G C. cf. corrugulatum, specimen USNM 1618861 F light microscopic picture G light microscopic close-up of microstructure H MOTU II, specimen USNM 1618853 I-L MOTU I, specimen ZSM-Mol- 20200039 I light microscopic picture J SEM scan K SEM close-up of mucro and L microsculpture M C. glabrum, specimen ZSM-Mol- 20200096 N C. glabellum auctt. non Adams, specimen ZSM-Mol- 20200074 O-R C. invisibile sp. nov., holotype ZSM-Mol- 20100320 O light microscopic picture P SEM scan Q SEM close-up of mucro and R microsculpture. Scale bars: 10 µm (R); 20 µm (C, K, L, Q); 50 µm (D, E) 100 µm (I, J, O, P); 200 µm (A, B, M, N).