A parsimony analysis of the relationships of Acanthemblemaria species was conducted based on 60 morphological characters. Outgroups included the two species of Ekemblemaria, the apparent sister group of Acanthemblemaria, and a hypothetical outgroup based on character
state distributions within potential second outgroups. The monophyly of Acanthemblemaria, containing 17 species, is supported by 5 synapomorphies: a fleshy or ossified process on the nasal bone adjacent to the first anterofrontal pore, spines on the raised ridges of the frontals, serrations
or spines on the orbital margin of the frontal, serrations or spines on the orbital margin of the lateral ethmoid, and two rows of palatine teeth. Three equally parsimonious trees were found, and a strict consensus tree revealed that relationships were fully resolved except within a portion
of the "hancocki species group" (Fig. 1). Species groups recognized by recent workers were supported and species relationships proved to be highly nested. The two species of Ekemblemaria and two species pairs of Acanthemblemaria follow the eastern Pacific-Caribbean distributional
track, with one of the latter indicating a rarely reported relationship between the southern Caribbean and the Galapagos Islands.
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