Parabomolochus globiceps nov. spec. (Copepoda, Cyclopoida) from the gills of Austroatherina smitti (Lahille) (Pisces, Atherinidae)

The material on which the following note is based was collected by the second author from the gill cavities of Austroatherina smitti (Lahille, 1929) from Mar del Plata, Argentine coastal waters, in the course of 1966 and consists of a number of female and male Bomolochid Copepods. In the course of the process of identification the copepods turned out to represent a new species, closely allied to but probably different from Parabomolochus xenomelanirisi (Carvalho, 1955), the only species of Bomolochidae so far known to occur along the Atlantic coast of South America. It was decided to draw up the description jointly; the drawings have been made after the dissected holo- and allotype by the first author, using Dr. Ramírez' sketches. Parabomolochus globiceps nov. spec. (figs. 1-6) Material examined. — Mar del Plata, Atlantic coast of Argentina, 1966. A fair number of specimens, consisting of ovigerous and non-ovigerous females and adult males, were taken from the gills and gill cavities of Austroatherina smitti (Lahille) (= Basilichthys smitti Lahille), local name "corno"). The following description is largely based on the 1.56 mm long holotype (non-ovigerous female) and the 0.80 mm long allotype (male); both have been dissected and the appendages mounted. Holo- and allotype are preserved in the Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands, along with 6 female paratypes (total length 1.55-1.80 mm, mean 1.66 mm) and one male paratype (total length 0.81 mm). Additional paratypes have been deposited in the Museum of Natural Sciences, La Plata, Argentina. Descripion of the female. — Total length, measured from the frontal part of the rostral plate to the end of the furca, 1.56 mm; greatest diameter,