Ringicula crassidens Gofas & Luque, 2021

Gofas, Serge, Luque, Ángel A., Oliver, Joan Daniel, Templado, José & Serrano, Alberto, 2021, The Mollusca of Galicia Bank (NE Atlantic Ocean), European Journal of Taxonomy 785 (1), pp. 1-114 : 70-71

Ringicula crassidens Gofas & Luque sp. nov.

urn:lsid:zoobank.org:act:8E4FB886-47AD-479C-9B49-238DD01F4F27

Fig. 29H‒K

Etymology

The specific name refers to the characteristic columellar folds (‘ crassidens ’, thick teeth).

Type material

Holotype GALICIA BANK • 1 sh ( Fig. 29 H ‒ I , 2.2 mm high); 42°28.81′ N, 11°50.03′ W; 1410 m; 8 Aug. 2011; BANGAL 0711 DR15; MNCN 15.05 /200140H.

Paratypes GALICIA BANK • 3 sh; same collection data as for holotype; MNCN 15.05 /200140P .

Other material examined

GALICIA BANK • 20 sh; 42°41.94′ N, 11°40.58′ W; 744 m; 31 Jul. 2011; BANGAL 0711 V4; MNCN .

Description

Shell small (holotype height 2.2 mm), semi-transparent, not very solid, globose, with a well defined suture and moderately elevated spire. Protoconch of a little more than half a whorl, smooth, without microsculpture even at high magnification. Teleoconch formed by 2½ whorls, the first one almost smooth, the last with about 38‒40 well marked, irregularly spaced spiral grooves which, under high magnification, appear as continuous series of square pits, and also with very fine growth lines; in the holotype there is also a growth stage in the last half whorl. Aperture slightly more than ⅔ of the total height, with two very marked columellar folds, the abapical one slightly larger, and with a very blunt and thick tooth in the middle of the parietal edge. Outer lip only slightly thickened, with a rounded edge. Very short siphonal canal. Colour uniformly white.

Remarks

This tiny species resembles Ringicula blanchardi Dautzenberg & H. Fischer, 1896 , described from the bathyal of the Azores, with which it shares the considerable development of the parietal tooth and the very clear spiral sculpture. It differs from it, however, because of its smaller size and more globose shape and lower spire with almost one whorl less. The great development of the parietal tooth, absent even in adults of R. nitida , indicates that, despite the scarce thickening of the outer lip, these are adult shells. The specimen from the GB reported by Rolán Mosquera (1983: 280) as Ringicula blanchardi Dautzenberg & H. Fischer, 1896 is in such a bad state that it cannot be recognized.

Figures

Fig. 29. Heterobranchia 2 (Cimidae,Acteonidae, Ringiculidae).A–B. Atomiscala islandica Warén, 1989, BANGAL 0711, DR15, 1410 m, 2.8 mm. C. Crenilabium exile (Jeffreys, 1870), BANGAL 0711, V10, 1720 m, 8.2 mm. D–E. Acteon monterosatoi Dautzenberg, 1889, SEAMOUNT 1, DW116, 985–1000 m, 2.5 mm. F–G. Ringicula nitida Verrill, 1872, BANGAL 0711, V2, 1706 m, 5.8 mm. H–I. Ringicula crassidens Gofas & Luque sp. nov., holotype (MNCN 15.05/200140H), BANGAL 0711, DR15, 2.2 mm high. J. Protoconch of a paratype (MNCN 15.05/200140P), same locality. K. Microsculpture of the second teleoconch whorl, same shell as J. Scale bars: A–I = 1 mm; J–K = 100 µm.

Fig. 2. Location of benthic samples used in this paper: SEAMOUNT 1 (turquoise), FAUNA II (red), ECOMARG 0709 (green) and INDEMARES BANGAL 0711 (deep blue). Symbols for sampling gears: rock dredge (circles; DW, R or DR), beam trawl (triangles; A, V or CP), otter trawl (squares; G or GOC). Isobaths every 200 m except for shallowest at 700 m; isobaths on the bank proper down to 2000 m from multibeam bathymetry (EEZ Project), completed with GEBCO regional bathymetry for the surroundings.