Leptaxinus minutus Verrill & Bush, 1898

Rodrigues, Clara F., Oliver, Graham & Cunha, Marina R., 2008, Thyasiroidea (Mollusca: Bivalvia) from the mud volcanoes of the Gulf of Cadiz (NE Atlantic), Zootaxa 1752, pp. 41-56 : 50-52

publication ID	1175-5326
persistent identifier	https://treatment.plazi.org/id/F6431C34-F712-E57C-FF27-F96C63EA8DCF
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scientific name	Leptaxinus minutus Verrill & Bush, 1898
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(Fig. 30)

Material examined. All from Gulf of Cadiz; two live-collected specimens, MSM01-03, stn 242 GKG 13, Mercator mud volcano, 35 º 17.870 'N, 06º 38.810 'W, 350 m, 6 May 2006 ( DBUA 00835.01); one live-collected specimen, TTR 16, stn AT 608 Gr, Darwin mud volcano, 35 º 23.531 N, 07º 11.475 W, 1115 m, 30 May 2006 ( DBUA 00836.01); two live-collected specimens, TTR 16, stn AT 604 Gr, Yuma mud volcano, 35 º 25.820 N, 07º 06.330W, 1030 m, 29 May 2006 ( DBUA 00836.02).

PLATE 4. Figures 24–25: Thyasira (Parathyasira) granulosa ( Monterosato, 1874) , Fig. 24 stn 321 GKG 22, Meknès mud volcano, 732 m ( DBUA 00828.03), Fig. 25 stn 242 GKG 13, Mercator mud volcano, 350 m ( DBUA 00828.02); Fig. 26 Thyasira obsoleta ( Verrill & Bush, 1898) stn 190 MUC 8, Captain Arutyunov mud volcano, 1322 m, ( DBUA 00831.02); Fig. 27 Thyasira tortuosa ( Jeffreys, 1881) AT 622 Gr, Porto mud volcano, 3902 m ( DBUA 00830.01); Fig. 28 Axinulus croulinensis ( Jeffreys, 1847) stn 242 GKG 13, Mercator mud volcano, 350 m ( DBUA 00832.02); Fig. 29 Mendicula ferruginosa ( Forbes, 1844) stn AT 575 B, Mercator mud volcano, 355 m ( DBUA 000834.01); Fig. 30 Leptaxinus minutus Verrill & Bush, 1898 , stn AT 608 Gr, Darwin mud volcano, 1115 m ( DBUA 00836.01).

Remarks. Leptaxinus minutus is rather tumid with a distinctly angular posterior outline but lacking a posterior sinus. The hinge is well developed with weak lateral folds and a tubercular cardinal. It was described from the northwest Atlantic and has been recorded from Norway and Iceland (Ockelmann in Oliver & Killeen 2002). The Gulf of Cadiz specimens agree well with the shell figured by Oliver and Killeen (2002, Pl. 25 C, D) but comes from a much greater depth. Dufour (2005) did not examine this species but the Gulf of Cadiz specimens have a Type 2 gill with a single demibranch and according to similar forms described by this author, it will doubtfully be symbiotic.

References

Dufour, S. (2005) Gill anatomy and the evolution of symbiosis in the bivalve family Thyasiridae. Biological Bulletin, 208, 200 - 212.

Forbes, E. (1844) Report on the Mollusca and Radiata of the Aegean sea, and on their distribution, considered as bearing on geology. Reports of the British Association for the Advancement of Science (1843), 130 - 193.

Jeffreys, J. G. (1847) Additional notices on British shells. Annals and Magazine of Natural History, 20, 16 - 19.

Jeffreys, J. G. (1881) On the Mollusca procured during the H. M. S. Lightning and Porcupine expedition (Part 3). Proceedings of the Zoological Society of London (1881), 693 - 724.

Monterosato, T. A. (1874) Recherches conchyliologiques, effectuees au Cap Santo Vito, en Sicile. (Traduz. dall'italiano di H. Crosse). Journal de Conchyliologie, 22 (3), 243 - 282.

Oliver, P. G. & Killeen, I. J. (2002) The Thyasiridae (Mollusca: Bivalvia) of the British Continental Shelf and North Sea Oilfields. An Identification Manual. Studies in Marine Biodiversity and Systematics from the National Museum of Wales, BIOMOR Reports, 3, 1 - 73.

Verrill, A. E. & Bush K. J. (1898) Revision of the deep-water Mollusca of the Atlantic coast of North America, with descriptions of new genera and species. Proceedings of the United States National Museum, 20, 775 - 901.