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Description: Body thin and moderately wide with a large round eye and very large terminal mouth. Pectoral and pelvic fins medium length, reaching much of the way to the vent, dorsal-fin base long and anal-fin base short, caudal peduncle moderately wide and short. The typical complement of melanophores on the head consists of one at the angle of the jaw and a sparse scattering on the top of the head. On the body there is one at the dorsal midline just forward of the first dorsal spine and then two large melanophores on the ventral midline of the caudal peduncle; one just behind the last anal-fin ray and one just before the first procurrent caudal-fin ray (the latter are often persistent through transition in serranines). Melanophores on the fins are prominent: the full complement consists of a patch on the membranes of the third to fifth dorsal-fin spines, several near the base of the first three anal-fin soft rays, extensively lining the membranes of the pectoral and pelvic fins and finally one at the base of the lower central caudal-fin rays. Internal melanophores are present around the sacculus and along the dorsal surface of the swim bladdder and the peritoneum extending to the gut near the vent. Varying patterns are common: earlier-stage larvae can be missing the melanophores on top of the head and/or the entire anal-fin, caudal peduncle, and caudal fin set of melanophores. Larvae approaching transition progressively lose the markings on their pectoral and pelvic fin rays and some larvae also develop a melanophore on the dorsal midline of the caudal peduncle (the saddle characteristic of juvenile hamlets). One or both of the ventral caudal peduncle spots occasionally are missing and sometimes the anal fin has additional melanophores (sometimes a full row) just distal to the base of the rays. A variety of additional melanophores occur in some individuals: just forward of the nasal bones, along the ventral aspect of the lower jaw, an additional melanophore on the caudal peduncle after the last anal-fin ray or a second spot on the base of the caudal-fin rays (usually on the upper central caudal-fin rays), or a few scattered on the caudal-fin rays. Pre-transitional larvae have a somewhat-narrowed vertical oval eye becoming fully round as transition approaches. Transitional larvae develop a fine scattering of discrete small surface melanophores, dense towards the anterior and fading towards the tail and the larval melanophores progressively disappear (usually starting with those on the pectoral-fin rays).
Hypoplectrus sp. larva