Comprehensive DescriptionRead full entry
This large genus includes eleven regional species, two of which have only recently been discovered (H. socialis from mangrove habitats in Belize (Randall and Lobel 2003) and H. burekae from deep reefs in the Gulf of Mexico (Weaver and Rocha 2007)). In addition, the northern (coastal USA) population of H. bivittatus is genetically divergent and represents a cryptic species. The phylogeny of the genus is presently in flux and it is likely that it will be split into three, or perhaps many more, genera (there are numerous unrelated lineages in the Indo-Pacific). Most Caribbean species share a basic fin-ray count of D-IX,11 A-III,12 and Pect-13 (H. maculipinna and H. cyanocephalus have slightly differing fin-ray counts).
My DNA-sequence analysis reveals that there is a large clade of Atlantic Halichoeres made up of H. bivittatus, H. garnoti, H. poeyi, H. radiatus, and H. cyanocephalus (and its Brazilian sibling H. dimidiatus). There is a smaller related clade made up of H. pictus and H. socialis (along with the eastern Pacific H. dispilus and H. insularis). My results confirm that H. maculipinna falls out well away from the other Halichoeres and nearer to Thalassoma (Barber and Bellwood 2005).
The larvae of a number of Halichoeres overlap in appearance and DNA sequencing is necessary to confirm the species for those larvae. The species do become distinct as they develop juvenile markings. The size at settlement for this genus is quite consistent, around 10-12 mm (interestingly, one eastern Pacific sibling, H. insularis, settles much larger, up to 22 mm SL). An unusual aspect of the early life history of these labrids is that larvae undergoing transition are not captured in pelagic sampling, but are found buried in sand and rubble on reefs. This attribute is shared with Thalassoma bifasciatum, but not with Doratonotus megalepis or the related parrotfishes, both of which begin transition while still pelagic and transitional larvae are commonly caught in nearshore collections. Interestingly, I did collect one transitional larva of H. poeyi at a nightlight in Panama and it was the single largest Halichoeres larvae out of many hundreds collected, i.e. 13.8 mm SL.