Taxonomy
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Tetraodontiformes
- Family: Tetraodontidae
- Genus: Colomesus
- Species: C. tocantinensis
- Authority: Carvalho, Corrêa & Alves, 2013
Description Colomesus tocantinensis is a species of freshwater pufferfish endemic to Brazil. It is closely related to Colomesus asellus (the Amazon puffer or South American freshwater puffer) but can be distinguished by specific morphological and meristic characteristics. Key diagnostic features include a unique coloration pattern consisting of five distinct dark dorsal saddles extending ventrally as bars or blotches along the flanks, and a distinct caudal fin pattern (typically banded or spotted). It possesses the typical tetraodontid body shape: robust, inflatable, lacking pelvic fins, and with a beak-like dental plate formed by fused teeth.
Distribution and Habitat This species is restricted to the Tocantins River basin in central Brazil. It inhabits freshwater environments, typically found in main river channels, tributaries, and flooded forest areas (igapós) with moderate to fast water flow and sandy or rocky substrates.
Biology and Ecology
- Diet: Like other tetraodontids, it is likely omnivorous with a preference for hard-shelled invertebrates (mollusks, crustaceans), utilizing its beak-like jaws to crush shells. It may also consume algae, plant matter, and small fish.
- Behavior: It is a demersal species. When threatened, it can inflate its body with water or air as a defense mechanism.
- Toxicity: Members of the family Tetraodontidae frequently contain tetrodotoxin (TTX), a potent neurotoxin, though toxicity levels vary by species, geographic population, and diet. Specific toxicity studies for C. tocantinensis are limited compared to marine counterparts.
Conservation Status As of the latest assessments, Colomesus tocantinensis has not been individually evaluated for the IUCN Red List of Threatened Species. Its restricted range within a single river basin undergoing significant anthropogenic pressure (hydroelectric dams, agriculture, mining) suggests potential vulnerability, but formal status remains unassigned.
Taxonomic History The species was formally described in 2013 based on specimens previously identified as Colomesus asellus. Molecular phylogenetic analysis and morphological review confirmed its status as a distinct species, resolving a long-standing taxonomic complexity within the genus Colomesus.
