A description of the smallest Triodon on record (Teleostei: Tetraodontiformes: Triodontidae)

Abstract

The smallest known specimen (20 mm standard length: SL) of Triodon macropterus Lesson is described and illustrated. It is easily distinguished from superficially similar tetraodontid and diodontid larvae or early juveniles of comparable size by the following characters: separate premaxillae in conjunction with the fused dentaries; the presence of multicuspid spinoid scales; the jet-black mark in front of the soft dorsal fin; the developing pelvis, which is visible through the distended skin of the belly; and the presence of a number of procurrent caudal fin rays. The small Triodon differs from the adult in possessing a huge head that measures 45% SL (vs. 28.5–32.7% in adult), the absence of the characteristic dewlap with the conspicuous lateral ocellus, and the structure of the scales and nostrils.