Conchocele undetermined

Oliver, P. Graham & Sellanes, Javier, 2005, New species of Thyasiridae from a methane seepage area off Concepción, Chile, Zootaxa 1092 (1), pp. 1-20 : 17-18

CONCHOCELE sp. indet.

Three worn and damaged valves ( Figs 43–45 ) of a large thyasirid (50mm) were collected at Station AGT 6, 40 nautical miles north­west off the Bay of Concepción, south­central Chile; 36°22.15 S, 73°42.85 W; 780 m depth, Coll. J. Sellanes and NMW.Z. 2005.4.5 .

The elongate outline, deep posterior sulcus and greatly elongate anterior adductor scar clearly place these shells in the genus Conchocele . The condition and small number of the valves makes any substantive study impossible but the known species are considered.

In the Pacific Ocean the genus Conchocele is known from two extant species both closely associated with chemoautotrophic assemblages, especially those at methane seeps, throughout the North Pacific Ocean ( Kamenev et al. 2001) and in the tropical western Pacific ( Okutani 2002).

Conchocele bisecta ( Conrad, 1849) is the best known species and has a pan North Pacific distribution along the coast of North America and those of Japan and Northern Russia. This species has been studied extensively and is reviewed by Kamenev et al. (2001). They discuss the historic confusion between C. bisecta and C. disjuncta as well as the more recently introduced name of C. scarlatoi Ivanova & Moskaletz, 1984 . They conclude that all are part of a single rather variable species that shows ontogenetic changes in outline. They did not, however, discuss the discovery of living Conchocele in the Caribbean, which was also identified as C. disjuncta Gabb, 1866 ( Boss 1967) . Kamenev et al. (2001) illustrated twelve shells and the Chilean shells are very similar to these. The only character that may lie outside the range of C. bisecta is the deeper excavation of the lunule giving a distinctly incurved rather than straight lunule margin.

Conchocele novaeguinensis Okutani, 2002 is a large species reaching 74 mm in length. Like the Chilean shells the lunule margin is incurved but more so. The material described consisted of a single shell and four valves thus making an assessment of variation very difficult.

Figures

FIGURES 43–45. Conchocele sp. indet. Station AGT 6, north­west off the Bay of Concepción, south­central Chile; 36°22.15 S, 73°42.85 W; 780m depth, Coll. J. Sellanes & NMW.Z.2005.4.5.