Apogon quadrisquamatus Longley

Baldwin, Carole C., Brito, Balam J., Smith, David G., Weigt, Lee A. & Escobar-Briones, Elva, 2011, Identification of early life-history stages of Caribbean Apogon (Perciformes: Apogonidae) through DNA Barcoding, Zootaxa 3133, pp. 1-36 : 24-25

Apogon quadrisquamatus Longley

Lineage B

Identification. Two additional adult specimens from Belize also were identified as A.quadrisquamatus (Appendix 1, one adult is shown in Fig. 29 ). As noted above, further study of the two A. quadrisquamatus lineages is needed. The adult specimens in A. quadrisquamatus lineage B provided the basis for genetic identification of three juveniles. All references to A. quadrisquamatus juveniles in this paper refer to these three specimens.

Juveniles ( Fig. 30 ). Body color in the juveniles (14.0–16.0 mm SL) is mostly orange, and there is a concentration of darker orange pigment in a bar beneath the posterior end of the second dorsal fin and another concentration in a blotch on the caudal peduncle. The entire head, including the snout and jaws, is orange. The dorsal, caudal, anal, and pelvic fins have distinctive blotches of yellow and orange pigment. There is a large yellow/orange blotch covering the entire first dorsal fin. There are two yellow/orange blotches on the anterior portion of the second dorsal fin, one distally and one just above the base of the fin. There are six yellow/orange blotches on the caudal fin: four on the outer caudal-fin rays, two dorsally and two ventrally; and two on the caudal-fin base. There are two yellow/orange blotches on the anterior portion of the anal fin, one distally and one just above the base of the fin. There is one orange blotch on the pelvic fin. There is symmetry in the position of the orange fin blotches such that those on the dorsal fins and dorsal lobe of the caudal fin mirror those on the pelvic fin, anal fin, and ventral lobe of the caudal fin. There are melanophores on top of the head and internally above the swimbladder and gut. There are 12 gill rakers on the lower limb of the first gill arch.

Comparisons Among Juveniles. Juveniles of A. quadrisquamatus most closely resemble young A. mosavi . They can be separated by the color of the fin markings—yellow and orange in A. quadrisquamatus vs. entirely orange in A. mosavi . Gill rakers on the lower limb of first gill arch are useful in separating preserved juvenilesusually 13 in A. quadrisquamatus , 14–15 in A. mosavi . Apogon quadrisquamatus juveniles also resemble A. robbyi juveniles in fin pigmentation, but in the latter this pigment is entirely yellow. Apogon quadrisquamatus lacks the orange body stripes characteristic of juvenile A. robbyi . Juvenile A. quadrisquamatus differs from other Apogon species in having the distinctive mirrored pattern of chromatophores on the median fins.

Figures

FIGURE 29. Apogon quadrisquamatus Lineage B, adult, 24.0 mm SL, DNA # BLZ 6180, photograph by J. Mounts and C. Baldwin.

FIGURE 30. Apogon quadrisquamatus Lineage B, juvenile, 14.0 mm SL, DNA # BLZ 7712, photograph by C. Baldwin and L. Weigt.