A female “Hemiulis” cf chlorocephalus, illustrating the striped appearance common to so many of these fishes. Credit: ベラ職人
The many colorful wrasses of the genus Halichoeres represent some of the most popular fishes for the reef aquarium, including such familiar names as the Christmas Wrasse, Melanurus Wrasse, Canary Wrasse and rarer beauties like the Earmuff Wrasse. With roughly 80 species to its name, the genus is the largest in the wrasse family and includes a great many species which possess confusingly similar color patterns. In particular, some two dozen species share a similar pattern of red and green stripes, rendering identification a difficult task for most aquarists. To help make life easier, I present a simplified photographic guide to this challenging group… First, we must begin this discussion with a pedantic note on this group’s taxonomy. Halichoeres is a mess at the moment. Molecular study has confirmed what has long been suspected—this genus does not represent a single evolutionary lineage but, rather, a mix of species which happen to share similar morphological characteristics. This is hinted at in the wide range of body shapes, ecologies and biogeographies contained within the current definition of the genus.
Phylogenetic tree of julidiine wrasses based on cytochrome oxidase 1 (genbank). Note that most of the basal branches are poorly resolved in this study, indicating a need for more diverse sampling to fully understand how the different ex-Halichoeres are truly related to one another. Click to enlarge.
The phylogenetic tree above illustrates the numerous distinct branches of Halichoeres, which corroborates nicely with earlier studies by Barber & Bellwood and Westneat & Alfaro. A great deal of work remains to be done before we fully understand how these fishes interrelate, but several major lineages stand out as distinct groups which likely need to be recognized as separate genera. In his monumental tome on wrasses, Rudie Kuiter laid out a framework for this, going so far as to coin several new names. While many of these changes appear warranted, others don’t, and the scientific community has mostly ignored his work. However, since Kuiter’s book is popular amongst aquarists and his names have gained at least some traction here, I will include this nomenclature in quotations. “Biochoeres” This clade (first named by Kuiter) has been widely recognized in molecular and morphological study and includes several popular aquarium fishes.… More:
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