Characterization of the geographical distribution pattern of the family Limacinidae Gray, 1840 (Mollusca - Gastropoda) in the waters of Northeastern of Brazil

摘要

The geographical distribution of the family Limacinidae in the Northeastern coast of Brazil was analyzed by taking into account the most relevant ecological aspects, aiming to increase the knowledge about the Family. The material was collected during the 4th Oceanographic Expedition of the REVIZEE program (Assessment of the Sustainable Potential of Living Resources in the Exclusive Economic Zone - Avalia??o do Potencial Sustentável de Recursos Vivos da Zona Econ?mica Exclusiva), in the months from September to December 2000. The studied area is located between 00°46’45”N and 13°53’45”S and between 29°15’40”W and 39°49’42”W, where six trips were performed, totaling 123 stations. The samples were collected using a bongo net (300- and 500-μm mesh size and net mouths of 60 cm in diameter) coupled with a digital flowmeter in oblique hauls from a depth of 0 to 200 m. For this study, the organisms retained in the 300-μm mesh were considered. On board the ship, the samples were placed in plastic containers, labeled, and fixed in 4% formaldehyde buffered with sodium tetraborate. In the laboratory, the samples were analyzed on a “Bogorov” tray under a binocular stereomicroscope. A total of 5655 individuals of the family Limacinidae were examined and were distributed as follows: 3 genera and 5 species. Representatives of the family Limacinidae were observed at high temperatures and salinities and were thus characterized as tropical and euhaline.Heliconoides inflatus was the species with the greatest abundance and frequency. Limacina lesueurii proved to be a rare, infrequently observed species. Limacina trochiformis andL. bulimoides were not abundant or frequent.Limacina lesueurii and L. bulimoides were recorded in neritic waters for the first time; this was also the first record ofL. lesueurii in the waters of Northeastern Brazil.Limacina trochiformis and L. bulimoidesexhibited wide distributions, although they were neither very frequently observed nor abundant. The distribution of Thielea helicoideswas restricted to oceanic waters. A correlation between Limacina bulimoides, Heliconoides inflatus, Thielea helicoides, and L. lesueurii was observed because they coexisted in the same niche.