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	https://doi.org/10.5281/zenodo.274249
DOI	https://doi.org/10.5281/zenodo.5657687
persistent identifier	https://treatment.plazi.org/id/F6431C34-F712-E57C-FF27-F96C63EA8DCF
treatment provided by	Plazi (2016-04-05 06:56:08, last updated 2024-11-27 06:10:18)
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 GKG13, Mercator mud volcano, 35º17.870'N, 06º38.810'W, 350 m, 6 May 2006 ( DBUA 00835.01); one live-collected specimen, TTR16, stn AT608Gr, Darwin mud volcano, 35º 23.531N, 07º 11.475W, 1115 m, 30 May 2006 ( DBUA 00836.01); two live-collected specimens, TTR16, stn AT604Gr, Yuma mud volcano, 35º 25.820N, 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 GKG22, Meknès mud volcano, 732 m ( DBUA 00828.03), Fig. 25 stn 242 GKG13, Mercator mud volcano, 350 m ( DBUA 00828.02); Fig. 26 Thyasira obsoleta ( Verrill & Bush, 1898) stn 190 MUC8, Captain Arutyunov mud volcano, 1322 m, ( DBUA 00831.02); Fig. 27 Thyasira tortuosa ( Jeffreys, 1881) AT 622Gr, Porto mud volcano, 3902 m ( DBUA 00830.01); Fig. 28 Axinulus croulinensis ( Jeffreys, 1847) stn 242 GKG13, Mercator mud volcano, 350 m ( DBUA 00832.02); Fig. 29 Mendicula ferruginosa ( Forbes, 1844) stn AT575B, Mercator mud volcano, 355 m ( DBUA 000834.01); Fig. 30 Leptaxinus minutus Verrill & Bush, 1898 , stn AT608Gr, 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.