Bryconops (Bryconops)

Comparisons within the subgenus Bryconops

Bryconops collettei and B. magoi possess the derived characters of the subgenus Bryconops (Chernoff and Machado-Allison, 1999), which include reduction in the ossification and denticulation of the gill rakers, despite being large fishes, and lack of maxillary teeth, with at most (and rarely) only a single, small conical tooth on one side. The subgenus Bryconops contains six species. B. alburnoides differs from the other five species by being much larger, reaching almost 200mm SL, and by having more lateral scales and branched anal-fin rays (see key). Importantly, B. alburnoides lacks an ocellus or clear areas containing coloration on the caudal fin. B. alburnoides often has pale to bright yellow suffused among the caudal fin rays, but this color is not concentrated within a circumscribed area on either fin lobe. Furthermore, the dorsal and adipose fins of B. alburnoides are dusky to pale yellow, never red.

The remaining five species in this subgenus comprise the B. caudomaculatus species complex. We refer the five species to this informal group because of their phenotypic similarity and because they have all been referred to, or synonymized with B. caudomaculatus at some point in their history. The following characteristics are common to the complex: (i) the dorsal fin has a crescent of red (a potential synapomorphy), (ii) the adipose fin is entirely red, and (iii) the caudal fin has at least a clear circumscribed area on the upper lobe that is either entirely, or partially, filled with red color. This ocellus is either well formed or irregular (Fig. 2). B. magoi and B. collettei differ from the other members by having the dorsal-fin ocellus only partially filled with red color (Fig. 3), the overall form of which appears as a streak or narrow ellipse; the color becomes diffuse and extends beyond the ocellus among the upper caudal-fin rays. This condition in the new species is independent of sex or state of maturity, since even specimens as small as 35 mm SL show the diffuse coloration pattern, though the color may be slightly less intense. Both B. disruptus and B. durbini have very few pored lateral scales (<31), whereas B. caudomaculatus, B. collettei, and B. magoi have more numerous pored scales (>36) that extend nearly to or beyond the end of the hypural plate.