Revision of the Genus Asterorhombus (Pleuronectiformes: Bothidae)
A recent definition of Asterorhombus is composed of only two characters: lack of sexual dimorphism; deep clefts in caudal bones (parhypural, hypurals, epurals). The genus currently contains seven nominal species: A. annulatus, A. bleekeri, A. osculus, A. cocosensis, A. fijiensis, A. intermedius, and A. filifer. Herein the genus is redefined, and as a result, A. annulatus, A. bleekeri, and A. osculus are transferred to Engyprosopon; Asterorhombus is reduced to four nominal species, A. cocosensis, A. fijiensis, A. intermedius, and A. filifer. Asterorhombus fijiensis is shown to be a junior synonym of A. cocosensis. Asterorhombus filifer and A. cocosensis are confirmed to have sexual dimorphism in interorbital width. Species of Asterorhombus were found to show two patterns of distribution: A. intermedius and A. cocosensis, Indo-West Pacific–distributed from the Indian Ocean to the western Pacific, not occurring nonmarginally on the Pacific Plate; A. filifer, Indo-Pacific–distributed from the Indian Ocean to nonmarginal localities on the Pacific Plate.Abstract
First gill arch showing palmate gill rakers (rakers blackened for accentuation) of Asterorhombus intermedius, 122.0 mm SL, BSKU 8373, Scale = 1 mm. (modified from drawing by K. Amaoka)
Caudal bones showing deep clefts. Asterorhombus intermedius, 122.0 mm SL, BSKU 8376. Scale = 5 mm. (modified from drawing by K. Amaoka). Hs = Haemal spine; Hy 1 + 2 = Hypurals 1 + 2; Phy = Parhypural; Pu 2 = Preural centrum 2; Ns = Neural spine; Pu 1 + Hy 3 + 4 = Preural centrum 1 + Hypurals 3 + 4; Ep + Hy 5 = Epural + Hypural 5
Interorbital width versus SL for three species of Asterorhombus. (A) A. cocosensis, (B) A. intermedius, (C) A. filifer
Morphology of first dorsal-fin rays of species of Asterorhombus. (A) A. cocosensis escal membrane partially unfolded (top), naturally folded (bottom; modified after Amaoka et al., 1994), (B) A. intermedius (modified after Lin et al., 1995). (C) A. filifer (modified after Hensley and Randall, 2003). Scale = 5 mm
Body depth (% SL) versus SL for three species of Asterorhombus. Arrows indicate data points for holotypes of A. fijiensis and A. cocosensis
Length of first dorsal-fin ray (% SL) versus SL for three species of Asterorhombus.
Valid species of Asterorhombus. (A) A. cocosensis, 48.6 mm SL, BPBM 32949, first dorsal-fin ray not extended; (B) A. intermedius, 84.3 mm SL, BPBM 19871; (C) A. filifer, holotype, 98.3 mm SL, BPBM 34871; (D) A. filifer, paratype, 63.2 mm SL, SAIAB(RUSI), 52650. Photos by J. Randall
Contributor Notes
Department of Marine Science, University of Puerto Rico, Mayagüez, Puerto Rico 00681–9013. dhensley@caribe.net