Another New Species of the Clingfish Genus Derilissus from the Western Atlantic (Pisces: Gobiesocidae)

Abstract

new genus and species of clingfish, Derilissus nanus, from the Bahama Islands. Subsequently, Fraser (1970) described two additional new species of Derilissus and utilized several generic characters neglected in previous clingfish descriptions. Briggs placed his new genus in the subfamily Gobiesocinae, an action of particular significance because Derilissus differs from all other genera included in this new world subfamily in having attached gill membranes. This, together with the discovery of another new genus from the western Atlantic, which clearly is unrelated to any genus currently included in the Gobiesocinae, has caused B6hlke and Robins (1970) to question the subfamilial classification within the family. A fourth new species of Derilissus, known from a single specimen, is described herein in order that its description may contribute toward a better understanding of the origin and affinities of this group of little known fishes. Terminology and methods follow those described by Briggs (1955), except for the caudal ray count. In many groups of fishes, including the closely related Callionymidae, the arrangement of the caudal rays may indicate generic relationships. In the following description the caudal rays are reported as a four-part formula, for example 2 + 76 + 1, indicates that there are 13 principal caudal rays (seven associated with the ventral hypural and six with the dorsal hypural) and three procurrent rays (two associated with the ventral hypural and one with the dorsal hypural). Principal caudal rays are defined as rays attached or articulating with the hypurals. Measurements are all straight-line measurements between points made with dial calipers. (Caudal-peduncle lengths used by Fraser apparently are projection measures rather than point to point measures.) All