Abstract

The systematics of the abyssal giant cusk-eel genus Spectrunculus was revised, based on the examination of 55 specimens recently collected from the northern Mid-Atlantic Ridge and 32 specimens from earlier collections in the Atlantic and Pacific Oceans. The conclusion of Nielsen and Hureau that only one sexually dimorphic species, S. grandis, exists, is rejected. The examination of meristics, external and internal morphometric characters, and body coloration allows the distinction between two species, requiring the resurrection of S. crassus. The major diagnostic characters are: number of dorsal-fin rays (135–148 in S. grandis vs. 121–139 in S. crassus), anal-fin rays (101–112 vs. 91–102), total vertebrae (77–88 vs. 71–78), otolith ostium depth in percentage of sulcus length (19–29% vs. 30–40%), and maximum standard length (<130 cm vs. <60 cm). In the North Atlantic S. crassus is most often darker than S. grandis, but because many exceptions exist, coloration proved an unreliable diagnostic character. The results are discussed with respect to evolution and ecology of two abundant sister species co-occurring in the lower bathyal and abyssal zones.

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