Identification of early life-history stages of Caribbean Apogon (Perciformes: Apogonidae) through DNA Barcoding Author Baldwin, Carole C. Author Brito, Balam J. Author Smith, David G. Author Weigt, Lee A. Author Escobar-Briones, Elva text Zootaxa 2011 3133 1 36 journal article 45772 10.5281/zenodo.279426 a38a17de-34b0-47b8-893f-1488915b8b04 1175-5326 279426 Apogon mosavi Dale Identification. Seventeen adult specimens of A. mosavi provided the basis for genetic identification of larvae and juveniles (Appendix 1, one adult is shown in Fig. 34 ). Adult A. mosavi can be distinguished from other Apogo n species by the combination of eight segmented anal-fin rays, body and lateral-line scales of similar size, no dark marking or bar beneath the second dorsal fin, a rectangular to oval bar present on the caudal peduncle that nearly reaches the dorsal and ventral body margins, and 14–15 (rarely 13 or 16) gill rakers on the lower limb of the first gill arch, ( Dale 1977 , Gon 2002 ). Our samples include 20 young specimens of A. mosavi , seven of them (14.0–17.0 mm SL) collected in the plankton net and 13 (14.0–20.0 mm SL) with fish anesthetics and dip nets (Appendix 1). As noted in the “Methods” section, we describe those collected in the plankton net as larvae and the others as juveniles. However, until melanophores appear on the caudal peduncle in large juveniles, there are no clear morphological differences between the two stages. FIGURE 34. Apogon mosavi , adult, 38.0 mm SL, DNA # BLZ 7131, photograph by J. Mounts. Juveniles ( Fig. 35 ). In the 15.0 to 20.0 mm SL juvenile specimens of A. mosavi ( Fig.35 a) the body is pale orange and there are no distinctive symmetrical markings on the fins. There is a large blotch of pigment on the caudal peduncle comprising orange chromatophores with sometimes a few melanophores mixed in. There are 14 or 15 gill rakers on the lower limb of the first arch. Fresh specimens of small juveniles (14.0–17.0 mm SL, Fig. 35 b) are mostly pale orange, with paler areas on the snout and jaws, beneath the anterior portion of the second dorsal fin, and on the anterior portion of the caudal peduncle. The dorsal, caudal, anal, and pelvic fins have distinctive blotches of orange pigment. There is a large orange blotch covering the entire first dorsal fin except the bases of the rays. Three orange blotches are present on the second dorsal fin — two on the anterior portion of the fin and the third on the posterior base of the fin. There are six 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. Three orange are present blotches on the anal fin — two on the anterior portion of the fin and the third on the posterior 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 gut. Comparisons Among Juveniles. Young juveniles of A. mosavi most closely resemble those of A. quadrisquamatus and A. robbyi in having distinctive patterns of chromatophores on the fins. See “Comparisons” under A. quadrisquamatus and A. robbyi juveniles for characters that distinguish them. Larvae ( Fig. 36 ). The seven larvae (14.0–17.0 mm SL) collected in the plankton have the same patterns of chromatophores and melanophores as those described above for small juveniles. The caudal-peduncle length ranges from 31–34% SL. Comparisons Among Larvae. Adult A. mosavi are most similar to A. quadrisquamatus and Apogon sp. 2. Larvae of A. quadrisquamatus are unknown, but juvenile A. quadrisquamatus and larval and juvenile A. mosavi have a similar pattern of fin pigment, suggesting that the larvae of A. quadrisquamatus may as well. Assuming the color of fin pigment of larval A. quadrisquamatus is the same as it is in juveniles, as is the case in A. mosavi , larval A. mosavi will differ from larval A. quadrisquamatus in having orange pigment on the fins (vs. orange and yellow). Likewise, larvae of A. robbyi are unknown, but they should differ from A. mosavi larvae in having yellow vs. orange fin pigment. The pattern of fin pigment in larval A. mosavi is sufficient to separate that species from larvae of other known Apogon . We know of no morphological features of preserved A. mosavi larvae that separate them from other Apogon larvae except the numerous melanophores on top of the head and long caudal peduncle (31– 34% SL) will distinguish them from larval A. aurolineatus (few or no melanlophores on top of the head and caudalpeduncle length 27–29% SL).