Diagnosis: Modal fin-ray counts of D-X,15 A-III,7 Pect-14 indicate the hamlets of Hypoplectrus. There is a "species flock" of numerous color variations of these fishes in the Caribbean, many of which can hybridize and the small juveniles are presumably indistinguishable. Variant larvae with slightly different melanophore patterns may either represent these different "morphospecies" or individual variation (likely the latter). DNA analysis may not be diagnostic, since it has been difficult to find consistent sequence divergence between color morphs (Puebla et al. 2007). The Caribbean morphospecies comprise H. aberrans, H. chlorurus, H. gemma, H. gummigutta, H. indigo, H. guttavarius, H. nigricans, H. providencia, H. puella, and H. unicolor. The median-fin ray count can be shared with some deep-water Caribbean serranids (Anthias nicholsi and A. asperilinguis, some Hemanthias aureorubens, and Pronotogrammus martinicensis), but the latter species have more pectoral-fin rays (16 or more). (DNA)
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
Hypoplectrus is a genus of fishes commonly known as hamlets, found mainly in coral reefs in the Caribbean Sea and the Gulf of Mexico, particularly around Florida and the Bahamas. They are a popular choice for hobbyist saltwater aquariums, and come in a variety of colors.
There are currently 17 recognized species in this genus:
Hamlets are simultaneous hermaphrodites (or synchronous hermaphrodites): They have both male and female sexual organs at the same time as an adult, meaning that they function as a male and female, making them one of the few vertebrates that are male and female at the same time. They seem quite at ease mating in front of divers, allowing observations in the wild to occur readily. They do not practice self-fertilization, but when they find a mate, the pair takes turns between which one acts as the male and which acts as the female through multiple matings, usually over the course of several nights. Hamlets preferentially mate with individuals of their same color pattern.[3]
{{cite journal}}: CS1 maint: unfit URL (link) Hypoplectrus is a genus of fishes commonly known as hamlets, found mainly in coral reefs in the Caribbean Sea and the Gulf of Mexico, particularly around Florida and the Bahamas. They are a popular choice for hobbyist saltwater aquariums, and come in a variety of colors.
