A new species of Bestiolina (Copepoda, Calanoida, Paracalanidae) from the Northwestern Atlantic with comments on the distribution of the genus

摘要

A new species of the paracalanid copepod genus Bestiolina Andronov, 1991 is described from Laguna Mandinga, a coastal lagoon system ofthe eastern coast of the southern Gulf of Mexico. Bestiolina mexicana n. sp. most closely resembles B. sinica (Shen & Lee, 1966) and B. arabica Ali, Al-Yamani, and Prusova, 2007 but can be distinguished from these and other known congeners by the number and presence of posterior surface spinules on the second and third exopodal segments of female legs 2–4, and the number of spinules on the anterior surface of the second endopodal segment of legs 2–4. This is the only species of the genus with 3, 0, 0 spines on the exopodal segments of leg 2 and 2, 3 spines on the second endopodal segments of legs 3 and 4, respectively. The mandible blade of B. mexicana n. sp. has 2 large supplementary teeth which have not been hitherto observed in the other species of the genus. This is the smallest species in the genus and has some reductions in the armature of the mouthparts. The new species has been known to occur only from this lagoonal system in the Gulf of Mexico and it is the first species of Bestiolina recorded in the northern Atlantic Ocean. The presence of a member of this primarily Indo-Malayan genus in the northwestern Atlantic probably represents the result of its final divergence and is explained by dispersal processes related to the Pliocene conditions.