Prionotus pictus, a new endemic species of searobin from the Galapagos Islands, Ecuador (Teleostei: Triglidae)

A new endemic searobin, Prionotus pictus n. sp., is described from the Galapagos Archipelago in Ecuador. The prior literature generally assumed that all Prionotus searobins in the archipelago were Prionotus miles, discovered by Charles Darwin on San Cristobal (Chatham Island) and described as endemic by Jenyns (1842). However, almost all underwater photographs from the islands, and surprisingly few museum specimens (three out of dozens), prove to be a quite different-appearing and colorful species. The new species is the island sister species to Prionotus albirostris which is found on deeper trawling grounds along the continental shelf, from Baja California to Peru. The second species found in the Archipelago, Darwin’s Prionotus miles, is uncommonly observed, rarely photographed underwater, and so far accounts for only a handful of the hundreds of searobins photographed in Galapagos. The COI mtDNA sequence (DNA barcode) of P. miles shows that it is an island sister species of continental Prionotus stephanophrys (4.87% sequence divergent), which it resembles in a number of basic features, in particular the smooth and gently sloping head and body shape and relatively shorter pectoral fins. A review of the original P. miles holotype and other museum specimens show that P. miles has been inadequately described and guidebooks typically amalgamate and combine characters of the two species, and almost all use photographs of P. pictus to illustrate P. miles. Prionotus pictus is distinguished from P. miles (and P. stephanophrys) by a concave, sharply sloped, duck-billed head profile with more prominent head spines; longer, colorful, and prominently spotted pectoral fins; a triangular spinous dorsal-fin outline with the second spine longest following a stout and serrated first spine of almost the same length; no black blotches on the distal fourth or fifth dorsal-spine membranes; thicker, prominently banded, free pectoral (walking) rays; and a variety of head, fin, and body markings. The new species differs from continental P. albirostris in having a rounded snout (vs. squared off) and distinctive colorful and contrasting patterns (hence pictus meaning “painted”). It is notable that a large, conspicuous, and relatively common new endemic fish species has eluded recognition for this long.