Larval development of five species of blenny (Teleostei: Blenniidae) from the western central North Atlantic, with a synopsis of blennioid family characters

Light trap collections on oil and gas platforms in the northern Gulf of Mexico off Louisiana from 1995 to 1997 contained young of tessellated blenny Hypsoblennius invemar, freckled blenny Hypsoblennius ionthas, featherduster blenny Hypleurochilus multifilis, molly miller Scartella cristata and seaweed blenny Parablennius marmoreus, which are described. Interspecific differences were: number of dorsal, anal, pelvic and caudal fin elements; number of mandibular pores; presence or absence of canine teeth, hypural 5 and pectoral fin pigment; width of gill openings; length of preopercular spines (in larvae). Size at settlement differed among some taxa, but all five species settled within a narrow size window of c. 1·5 mm standard length (LS). Hypsoblennius invemar, H. ionthas, H. multifilis and S. cristata settled at mean sizes between 11·3 and 12·1 mm LS, whereas P. marmoreus settled at a mean size of 19·3 mm LS. Sexually dimorphic differences were consistently evident by 17–18 mm LS in all species but P. marmoreus. The two smallest blennies with external characters normally associated with sexual maturity were a 20 mm male and 21 mm female H. multifilis. Primary caudal fin rays began to bifurcate between 17·0 and 18·3 mm LS in H. invemar, H. ionthas, H. multifilis and S. cristata. Hypleurochilus multifilis displayed the external characteristics of being sexually mature at 20–21 mm LS. Thus, bifurcation of primary caudal fin rays was an indicator of approaching sexual maturity in H. multifilis and this may also be true in the other species studied.