Gymnobela chyta Watson 1881

• Main Authors: Figueira, Raquel Medeiros Andrade, Absalão, Ricardo Silva
• Format: Text
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Gastropoda; Neogastropoda; Raphitomidae; Gymnobela; Gymnobela chyta; Ricardo; Northeast Atlantic; Northwest Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.5632977; https://zenodo.org/record/5632977

Gymnobela chyta (Watson, 1881) (Figs. 31–32) Pleurotoma ( Defrancia ) chyta Watson, 1881: 466. Clathurella chyta (Watson, 1881): Watson (1886: 358, pl. 18, fig. 4); Gymnobela chyta (Watson, 1881): Bouchet & Warén (1980: 58, fig. 110); Pleurotoma ( Defrancia ) peripla Dall, 1881: 68; Dall (1889: 115, pl. 11, fig. 17). Type material : Holotype BMNH 1887.2. 9.1108 Type locality : West of Azores, sta. 73 (38 º 30 ’N, 31 º 14 ’W), 1829 m. Material examined : 16469 [1] OP I # 13; 16421 [4] OP I # 15; 16440 [3] OP I # 16; 16594 [2] OP II # 13 - 2; 16617 [3] OP II # 15; 16541 [16] OP II # 16 - 1; 17205 [1] OP I # 44; 14961 [1] OP I # 54; 19178 [2] OP I # 61. Description : Shell moderately plump, spire moderately high, yellowish, up to 44.48 mm long. Protoconch with about five whorls. Protoconch 1 with spiral rows of tiny crosses. Protoconch 2 with diagonal cancellation on the lower 2 / 3 of the whorls and arched axial riblets on the upper third. Clear-cut proto-teleoconch boundary. Teleoconch whorls with a strong shoulder at the upper part, forming a concave region between the suture and the whorl shoulder. Axial sculpture consists of many short prosocline axial riblets below the suture but not reaching the whorl shoulder, and 12–14 opisthocline axial folds (on the sixth whorl). Axial folds strongly angled on the whorl shoulder, extending to the base and becoming weaker toward the aperture. Numerous feeble spiral threads evenly sculpture the entire surface of the whorls below the shoulder, including the base. Concave region between the suture and the whorl shoulder crowded with minute granules. Suture moderately shallow. Base medium-sized. Anal sinus hardly discernible. Inner lip thin and reflected over parietal wall. Outer lip thin. Anterior siphonal canal short and wide. Aperture elliptical. Geographic distribution : Northeast Atlantic: Azores (Watson, 1886); Spain (Bouchet & Warén, 1980). Northwest Atlantic: Mexico (Dall, 1881; Dall, 1889). Southwest Atlantic: Campos Basin, Rio de Janeiro (this paper). Bathymetry : 750 m (this paper)– 2320 m (Bouchet & Warén, 1980). Discussion : Our material matches perfectly with the original illustration of the type of G . chyta (Watson, 1886: pl. XVIII, fig. 4). Bouchet & Warén (1980: 51, fig. 110) also illustrated the same species, but showed it as slightly more slender. Gymnobela chyta is reported for the first time in South Atlantic waters (21–22 ºS). It was previously known to occur in Spain, Azores and Mexico (21 ºN). Its bathymetric range is also increased. The shallowest depth previously reported was 1170 m (Dall, 1881) and it has now been found at 750 m. : Published as part of Figueira, Raquel Medeiros Andrade & Absalão, Ricardo Silva, 2012, Deep-water Raphitomidae (Mollusca, Gastropoda, Conoidea) from the Campos Basin, southeast Brazil, pp. 1-27 in Zootaxa 3527 on pages 18-19, DOI: 10.5281/zenodo.210977 : {"references": ["Watson, R. B. (1881) Mollusca of H. M. S. Challenger Expedition. Parts VIII-X. Journal of the Linnean Society (London), 15, 388 - 475.", "Watson, R. B. (1886) Report on the Scaphopoda and Gasteropoda collected by H. M. S. Challenger during the years 1873 - 1876. Report on the scientific results of the voyage of H. M. S. Challenger during the years of 1873 - 1876, 15 (42), 1 - 680, 53 pls.", "Bouchet, P. & Waren, A. (1980) Revision of the Northeast Atlantic Bathyal and abyssal Turridae (Mollusca, Gastropoda). Journal of Molluscan Studies, Supplement 8, 1 - 119.", "Dall, W. H. (1881) Reports on the results of dredging, under the supervision of Alexander Agassiz, in the Gulf of Mexico, and in the Caribbean Sea, 1877 - 79, by the United States Coast Survey Steamer ' Blake'. Bulletin of the Museum of Comparative Zoology, 9, 33 - 144.", "Dall, W. H. (1889) Reports on the results of dredgings, under the supervision of Alexander Agassiz, in the Gulf of Mexico (1877 - 78) and in the Caribbean Sea (1879 - 80), by the U. S. Coast Survey Steamer ' Blake'. Bulletin of the Museum of Comparative Zoology, 18, 1 - 492, pls. 10 - 40."]}