The subfamilies Margaritinae and Calliostomatinae from South Shetland Islands to Bellinghausen Sea: species diversity and unknown identities

ALDEA C., D. G. ZELAYA Y J. S. TRONCOSO

Antwerp, Bélgica

Congreso; World Congress of Malacology; 2007

Unitas Malacologica

During the Spanish Antarctic Expeditions BENTART (2003 and 2006) numerous species from the subtidal to deep-water mollusks were sampled. This research focused on West Antarctica, from South Shetland Islands to Bellinghsausen Sea. Among these samples, trochids were particularly abundant, both in number of species and specimens. The abundance of material coming from the BENTART expeditions represented a great opportunity to obtain new information of some of these taxa, as well as further precisions on the distributional ranges of the species. Despite the great diversification exhibit by Trochidae in the Southern Ocean, there are many species with doubtful taxonomic status and unknown identities, mainly from Bellingshausen Sea, an area poorly sampled. In this study we focus on the subfamilies Margaritinae and Calliostomatinae. The Margaritinae were represented by five species: Antimargarita dulcis (Smith, 1907), A. smithiana (Hedley, 1916), Margarella antarctica (Lamy, 1905), M. refulges (Smith, 1907) and Tropidomarga biangulata Powell, 1951. First records for Antimargarita dulcis, A. smithiana and Margarella refulges are presented. The diagnostic characters for each of these species are revised and is discusses its affinities with others trochids species. The Calliostomatinae were represented by one, most probably new species of Falsimargarita, from South Shetland Islands. This species has a shell very close to the Margaritinae Antimargarita dulcis, and the gross anatomy of this species is studied. In this sense the genera Falsimargarita Powell, 1951 and Antimargarita, 1951, differ in their radula, but share morphological features of the shell, being able to observe a patter common of external iridescence and predominant spiral cords on a more delicate axial sculpture. Furthermore, we perform a comparison of the shell morphology of the new Falsimargarita species with the other species of this genus presently known in the Antarctic waters.