Early ontogeny of tetra Markiana nigripinnis (Characiformes: Characidae)

Abstract The early development of Markiana nigripinnis is described by morphological characters, pigmentation, and morphometry. Larvae were obtained through semi-natural breeding, collected, fixed, and identified according to their development. Eighty individuals with standard lengths ranging from 3.1 to 24.3 mm were analyzed. Larvae are poorly developed at hatching, with a relatively large yolk sac and finfold. At the preflexion stage, the eyes are pigmented, the mouth and anus are functional, the yolk is completely absorbed, and the pectoral fin bud emerges. At flexion, the first rays of the caudal, anal, and dorsal fins become evident. The pelvic fin bud emerges only at the postflexion stage, in addition to the complete absorption of the finfold. Pigmentation is distributed throughout the body, with a greater concentration on the top of the head, around the mouth, and at the base of the caudal fin. The myomere total number ranged from 34 to 49 (16–23 preanal, and 18–27 postanal). Juveniles show morphological characteristics like adults. The fins ray number are pectoral: 11–13, pelvic: 5–7, dorsal: 8–11, caudal: 16–27, and anal 30–47. The morphometric relationships reveal variations in growth along the early ontogeny of the species.