Taxonomic Status, Biology, and Distribution of Hawaiian Lentipes, a Diadromous Goby

Abstract

Three species ascribed to the goby genus Lentipes include two from Hawaii, L. concolor (Gill 1860) and L. seminudus Gunther (1880), and one from the Gulf of Guinea, L. bustamantaei Boulenger (1916). The Hawaiian species were described from single specimens of different sex. Specimens collected recently provide evidence that Hawaiian Lentipes comprise a single, sexually dimorphic species. The African species differs significantly and more nearly resembles Sicydium. Lentipes now must be considered a monotypic genus (L. concolor) endemic to the Hawaiian archipelago. The genus is distinguished by weak scalation (2-150 cycloid scales per side on posterior trunk), five subequa1 and one shorter spine in the first dorsal fin, 16 pectoral rays, and one projecting ossified gill raker on the first arch. The sexes differ mainly in head shape, relative mouth size, dentition, spacing of dorsal fins, and coloration. The female is drab; the male is yellow to red posteriorly and has a white anal fin margin. Adult Lentipes, omnivorous and growing to nearly 140 mm TL, inhabit pristine steep-gradient streams. Larvae develop in the ocean and appear at stream mouths as post1arvae less than 20 mm 10ng.Upstream'migrants are capable of ascending high waterfalls, where they reach areas of permanent residence. Surveys located Lentipes in 22 streams (6 percent of the total streams in the archipelago) but the goby was abundant in only a few of them. Because of sparse Lentipes populations and incompatibility with past and continuing habitat degradation, endangered status recognition is recommended.