The genus Olivancillaria d´Orbigny 1840 (Gastropoda: Olividae): endemic to the Southwestern Atlantic?

TESO, V.; PASTORINO, G.

Phuket

Congreso; 17th International Congress of UNITAS MALACOLOGICA; 2010

UNITAS MALACOLOGICA

Species included in Olivancillaria d´Orbigny, 1840 are mostly known from the Southwestern Atlantic. They usually live in shallow water down to about 50 m depth in the Argentine Malacological Province, ranging from Bahia (Brazil) to Golfo Nuevo (Argentina). Only three species living beyond this area have been assigned to this genus, i.e., O. acuminata and O. nana, from Mauritania to Angola along the eastern coast of Africa and O. gibbosa from the Indian Ocean. However, such a generic placement is at least doubtful.  An in-depth revision of all nominal species of Olivancillaria from South America was undertaken. Research was focused on the description of each species, analysis of synonymous names, illustration of characters and distribution patterns, together with SEM illustrations of protoconch, shell ultrastructure, radulae, penes, siphon papillae and egg capsules of all known species. Additionally, interspecific shell variation was analyzed using geometric morphometric techniques. Eight living species were recognized as valid: O. deshayesiana, O. vesica, O. urceus, O. auricularia, O. contortuplicata, O. orbignyi, O. teaguei and O. carcellesi. All are restricted to the Southwestern Atlantic from Bahia state, Brazil (~12°S) to Chubut province (42°37’S), Argentina, ranging from the intertidal zone down to70 m depth. A comparison with other genera (e.g., Agaronia) suggests that Olivancillaria is endemic to Southwestern Atlantic waters.