Apogon quadrisquamatus Longley

Apogon quadrisquamatus Longley

Lineage A

Identification. A single adult specimen from Belize (Fig. 28) constitutes the genetic lineage herein referred to as Apogon quadrisquamatus Lineage A. Adult A. quadrisquamatus can be distinguished from other Apogon by the combination of eight segmented anal-fin rays; lateral-line and body scales of similar size; no dark marking or bar beneath the second dorsal fin; caudal-peduncle spot small, circular, of varying intensity, and usually restricted to middle of caudal peduncle; and 12–14, modally 13, gill rakers on the lower limb of the first arch, (Böhlke & Chaplin 1993, Dale 1977, Gon 2002). The adult specimen in this lineage keys to Apogon quadrisquamatus and is distinct from A. mosavi and Apogon sp. 2 in having a circular blotch of melanophores in the center of the peduncle vs. a rectangular bar (A. mosavi) or very diffuse oval (Apogon sp. 2) of melanophores. Apogon robbyi has a similar circular, basicaudal blotch, but that species is distinctive in having dusky stripes on the trunk. Apogon quadrisquamatus Lineage A is further distinguished from A. mosavi in having 12 gill rakers on the lower limb of the first arch (possibly a rudiment is forming), vs. 14–15 in A. mosavi. The body is mostly orange, and the median fins are yellow. Additional material and further study are needed to determine if this lineage and A. quadrisquamatus Lineage B (see next section) are morphologically distinct, and, if so, which one represents A. quadrisquamatus Longley 1934. No larvae or juveniles match the single adult specimen of this lineage in our genetic analysis.