Plectropomus and Its Allies.

—The genus Plectropomus was recovered as monophyletic; however, both the monotypic Gonioplectrus and Saloptia are included in a larger monophyletic clade. All three genera share a relatively low dorsal-fin spine count (7–8 vs. 9–11 in the remaining grouper genera). Smith (1964), Leis (1986), and Heemstra and Randall (1993) hypothesized a close relationship between Saloptia and Plectropomus . Species in these genera are the only groupers with a single supraneural bone, low dorsal-fin spine count, three large antrorse spines on the lower edge of the preopercle, and only 13 branched caudal-fin rays. Saloptia has been treated as a monotypic genus on the basis of the relative strength of the median fin spines (‘‘strong’’ in Saloptia and ‘‘weak’’ in Plectropomus; Heemstra and Randall, 1993) and an absence of enlarged canine teeth on the lower jaw. Given the numerous synapomorphies shared by these genera, the argument for retaining S. powelli in a monotypic genus is relatively weak. The loss of canine teeth appears to be an autapomorphic character and is insufficient to exclude the species from Plectropomus .

The monotypic genus Gonioplectrus is also present in this clade (clade A, Figs. 1, 2). This is not entirely surprising as it shares the low number of dorsal-fin spines (8) with species of Plectropomus . Gonioplectrus has two well-developed supraneurals (versus only one in Plectropomus and Saloptia), 15 branched caudal-fin rays (versus 13 in Plectropomus and Saloptia), a prominent knob on the lower corner of the maxilla (absent in Cephalopholis, Plectropomus, and Saloptia) and unique cranial morphology (Heemstra and Randall, 1993). Given these differences, Gonioplectrus appears to be a related, but distinct genus and is retained for the single species G. hispanus .

Also included in the monophyletic clade A (Fig. 1) are members of the genus Variola . With nine dorsal-fin spines, this genus would seem to be closely related to Cephalopholis; however, it is clear from the analyses that this is not the case. Species of Variola are the only grouper species with a pronounced, lunate tail. While closely allied with Plectropomus and Gonioplectrus, the genus Variola appears to be a distinct group among the groupers with low dorsal-fin spine counts and is therefore retained.