Abstract
A new miniature species of the family Characidae from Marajó Island, Pará State, Brazil is described and assigned to the genus Tyttobrycon. The new species can be distinguished from its congeners primarily by having multicuspid teeth on jaws, and additionally by having the combination of 5-7 premaxillary teeth, dorsal fin only with scattered melanophores and the presence of an adipose fin.
Highlights
The genus Tyttobrycon Géry includes four miniature characid species from the Amazon basin: T. dorsimaculatus Géry, T. hamatus Géry, T. spinosus Géry, and T. xeruini Géry. These species are characterized by a suite of apparently paedomorphic features, such as number of infraorbitals reduced, few or none perforated lateral line scales, and number of fin rays reduced, and by the presence of some secondary sexual specializations such as bony hooks on fins and developed procurrent caudal-fin rays, as in T. spinosus (Géry, 1973)
The new species share most of the characters proposed by Géry (1973) for the genus Tyttobrycon and closely resembles T. dorsimaculatus, described from the rio Mamoré, a tributary of the rio Madeira basin
The genus Tyttobrycon was not examined, but was provisionally considered as belonging to Aphyoditeinae. At this point we think that any effort to reconstruct relationships of our new species within the Characidae would require a thorough phylogenetic analysis, which is beyond the scope of this work
Summary
The genus Tyttobrycon Géry includes four miniature characid species (sensu Weitzman & Vari, 1988) from the Amazon basin: T. dorsimaculatus Géry, T. hamatus Géry, T. spinosus Géry, and T. xeruini Géry. These species are characterized by a suite of apparently paedomorphic features, such as number of infraorbitals reduced, few or none perforated lateral line scales, and number of fin rays reduced, and by the presence of some secondary sexual specializations such as bony hooks on fins and developed procurrent caudal-fin rays, as in T. spinosus (Géry, 1973). The new species share most of the characters proposed by Géry (1973) for the genus Tyttobrycon and closely resembles T. dorsimaculatus, described from the rio Mamoré, a tributary of the rio Madeira basin. The aim of the present contribution is to formally describe the new species based on its unique combination of morphological features
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