Comprehensive DescriptionRead full entry
The genus Paraclinus has fewer species in the western Atlantic than the three other labrisomid genera discussed above (many more Paraclinus species occur in the eastern Pacific). Juveniles and adults are easily recognized by their dorsal fin, which is either all spines or all-but-one spines (with a single segmented ray at the end of the fin). Combinations of fin-ray counts can identify most species. Three species are widespread and common in shallow waters, but they are tiny and well-camouflaged and thus rarely seen underwater: P. nigripinnis (D-30+1 A-II,17-18 Pect-13), P. fasciatus (D-29-30 A-II,18-20 Pect-13), and P. cingulatus (D-28 A-II,15-16 Pect-12). Two species live only on deep reefs and dropoffs and are quite rare: P. barbatus (D-28-29+1 A-II,19-20 Pect-13, chin barbel), and P. infrons (D-26-28+1 A-II,18 Pect-12, no nuchal cirri). The remaining three species have unusual distributions and comprise P. marmoratus, commonly found only in Florida and NE Venezuela, rare in the Bahamas and Belize (D-28+1 A-II,19-21 Pect-13, extended first dorsal spines, often anal-fin ocellus; shallow lagoon patch reefs); P. grandicornis, found only in Florida, the Bahamas, and the Virgin Islands, living within sponges (D-27+1 A-II,18 Pect-12, large orbital cirrus); and P. naeorhegmis from the Bahamas, rare in Belize and Providencia (D-26-27 A-II,15-16 Pect-13; well-washed channels). Originally described with very narrow ranges, more recent surveys and photograph collections reveal that most species (or, more likely, allopatric sets of cryptic species) are wide-ranging throughout the region.
Pre-transitional larvae of Paraclinus are relatively small and often resemble generic labrisomid larvae, with no distinctive morphology or markings. The one diagnostic feature is that the posterior dorsal fin is made up of spines instead of soft rays. On well-developed and well-preserved larvae this feature easily confirms the identification, however the posterior spines of Paraclinus tend to be broader than typical spines and are recognized as spines mostly by the absence of segment divisions and the bulb at the base of soft rays. On less-developed larvae and larvae in poor condition, this distinction can be difficult to assess.
An additional character quickly separating Paraclinus larvae from the far more abundant larvae of Malacoctenus and Labrisomus is the absence of cranial melanophores. Paraclinus larvae also have no obvious preopercular spines, while many immature Malacoctenus and Labrisomus (and Starksia) larvae have preopercular spines at the size of overlap with Paraclinus larvae. A useful character, even on poorly preserved larvae, is the number of procurrent caudal-fin rays: Paraclinus larvae have only 3 or 4 vs. 6 to 10 in Malacoctenus and Labrisomus (and 5 to 6 in Starksia).
Other than the diagnostic dorsal-fin spine complement, Paraclinus larvae can be distinguished from the similar Starksia larvae by the consistent presence of the deep nuchal and deep pelvic melanophores and often the cheek melanophore. Deep melanophores, however, are not always visible on well-developed larvae. Interestingly, transitional Paraclinus larvae collected at night over the reef do not have the metamorphic melanophore patterns over the head typical for transitional Starksia larvae and frequent on larvae of Malacoctenus and Labrisomus. Nevertheless, by the morning (in collections made by unattended crest nets), metamorphic melanophores have developed.