Magnella extensa Dall 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; Magnella; Magnella extensa; Abbott; Ricardo; Sudeste; Northwest Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.5632969; https://zenodo.org/record/5632969

Magnella extensa (Dall, 1881) (Figs. 24–26) Pleurotoma ( Bela ) blakeana extensa Dall, 1881: 55: Dall (1889: 126, pl. 10, fig. 2); Pleurotomella extensa (Dall, 1881): Abbott (1974: 290, ind. 3452); Gymnobela extensa (Dall, 1881): Absalão et al . (2005: 33, fig. 92); Rios (2009: 350, species 908); Pleurotoma ( Defrancia ) streptophora Watson, 1881: 464. Clathurella streptophora (Watson, 1881): Watson (1886: 356, pl. 19, fig. 8). Type material : Syntypes MCZ 7146, MCZ 7147, MCZ 7148. Type locality : Cape San Antonio, Cuba, 755–1170 m; Yucatan, Mexico, Blake sta. 35 (23 º 52 ’N, 88 º 58 ’W), 1470 m. Material examined : Type material and 18474 [1] OP II # 60; 18475 [1] OP II # 75; 18476 [2] OP II # 84; 18477 [1] OP II # 86; 18478 [1] OP I # 50 A; 18479 [4] OP I # 75. Description : Shell oblong-biconical, white, up to 5.08 mm long. Protoconch with about 3.5 whorls. Protoconch 1 with spiral rows of tiny crosses. Protoconch 2 with diagonal cancellation on the lower 3 / 4 of the whorls, and axial riblets crossed by very fine and faint spiral threads on the upper fourth. Clear-cut prototeleoconch boundary. Teleoconch with a strong subsutural spiral cord and another strong spiral cord on the upper half of the whorls. Axial sculpture consists of 14–16 axial ribs (on the fourth whorl), forming pointed nodules where they cross the spiral cords. Axial ribs extend over base. Shell surface with granules aligned spirally. Suture well marked. Base short, with nine weak spiral cordlets. Anal sinus not discernible. Outer lip relatively thick. Anterior siphonal canal oblique, very short and wide. Aperture elliptical. Geographic distribution : Northwest Atlantic: Cuba (Dall, 1881; Dall, 1889). Southwest Atlantic: Bahia, Espírito Santo and Rio de Janeiro (Absalão et al ., 2005); Campos Basin, Rio de Janeiro (this paper). Bathymetry : 450–2076 m (Absalão et al ., 2005). Discussion : Our material matches well with the original illustration of the species (Dall, 1889: pl. 10, fig. 2). When compared directly with the syntype (fig. 24), our specimens show a more prominent subsutural row of nodules and a stronger spiral ornamentation on the base. We believe these differences to represent intraspecific variation. This species was originally described as a subspecies of M . blakeana . It can be distinguished from M . blakeana by its much thinner profile, glossy surface, less numerous spiral ornamentation and strong subsutural row of nodules. : 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 15-16, DOI: 10.5281/zenodo.210977 : {"references": ["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.", "Abbott, R. T. (1974) American Seashells. 2., pp. 663, 24 pls. Van Nostrand Reinhold Co., New York.", "Absalao R. S., Pimenta, A. D. & Caetano, C. H. S. (2005) Turridae (Mollusca, Neogastropoda, Conoidea) coletados no litoral Sudeste do Brasil, Programa REVIZEE \" score \" central. Biociencias, 13 (1), 19 - 47.", "Rios, E. C. (2009) Compendium of Brazilian sea shells. pp. 668. Fundacao Universidade do Rio Grande, Rio Grande.", "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."]}