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| Corydoras colossus Tencatt, Grant & Bentley, 2023 Photos by Hans Evers & Steven Grant |
Abstract
A new species of Corydoras is described from the rio Jutaí, Amazon basin, Brazil. The new species can be distinguished from its congeners by having the following features: (I) ventral surface of trunk entirely or almost entirely covered by small- to relatively large-sized coalescent platelets, forming a typical mosaic-like pattern; (II) large, arched dark brown or black patch extending from interopercle region to posterior process of parieto-supraoccipital, transversally crossing the orbit and forming a typical mask-like blotch; (III) absence of conspicuous dark markings on caudal fin; (IV) absence of longitudinal rows of dark blotches on flanks; (V) region of first dorsolateral body plate surrounding posterior process of parieto-supraoccipital clearly lighter than remaining portions of head, forming a V-shaped pattern in dorsal view; (VI) anterior portion of dorsal fin with a conspicuous dark patch; and (VII) anterior portion of dorsal-fin base with conspicuous concentration of dark brown or black chromatophores, forming a dark patch slightly darker than ground color of body. A discussion on the possible positive adaptive value of the color pattern is also provided.
Keywords: Aposematism; Corydoradinae; Corydoras sp. CW45; Crypsis; Taxonomy
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| Variations in color pattern in life of Corydoras colossus in lateral view, showing the general color pattern in life of the holotype (A); MNRJ 54421, 44.5 mm SL), a paratype with a paler pattern (B); not labelled as photographed after preservation, catalog number untraceable), and of an uncatalogued aquarium specimen (not measured) with a darker pattern (C). Photos by Steven Grant. |
Corydoras colossus, new species
Corydoras sp. CW045. —Alexandrou, Taylor, 2011:115
(“CW45”; phylogeny; member of lineage 9). —Fuller, Evers, 2011:88 (code number).
Diagnosis. Corydoras colossus can be distinguished from its congeners, except for C. araguaiaensis Sands, 1990, C. burgessi Axelrod, 1987, C. concolor Weitzman, 1961, C. esperanzae Castro, 1987, C. evelynae Rössel, 1963, C. eversi Tencatt & Britto, 2016, C. granti Tencatt, Lima & Britto, 2019, C. julii Steindachner, 1906, C. melanistius Regan, 1912, C. oiapoquensis Nijssen, 1972, C. parallelus Burgess, 1993, C. pavanelliae Tencatt & Ohara, 2016, C. polystictus Regan, 1912, C. schwartzi Rössel, 1963, C. surinamensis Nijssen, 1970, C. trilineatus Cope, 1872, and C. xinguensis Nijssen, 1972, by having ventral surface of trunk with small- to relatively large-sized coalescent platelets, forming a typical mosaic-like pattern (vs. platelets on ventral surface of trunk, when present, small-sized and not coalescent, not forming a mosaic-like pattern). The new species can be distinguished from C. araguaiaensis, C. eversi, C. granti, C. julii, C. pavanelliae, C. polystictus, C. trilineatus, and C. xinguensis by the presence of a large, arched dark brown or black patch extending from interopercle region to posterior process of parieto-supraoccipital, transversally crossing orbit and forming typical mask-like blotch (vs. mask-like blotch absent); from C. evelynae, C. oiapoquensis, C. schwartzi, and C. surinamensis by the absence of conspicuous dark markings on caudal fin (vs. caudal fin with conspicuous dark brown or black blotches, which are typically roughly transversally aligned, forming bars); from C. parallelus plus C. evelynae, C. schwartzi and C. surinamensis by the absence of longitudinal rows of dark blotches on flanks (vs. at least two rows of conspicuous dark blotches roughly longitudinally aligned on flanks, which can be variably fused, forming stripes); from C. concolor and C. esperanzae by having region of first dorsolateral body plate surrounding posterior process of parieto-supraoccipital clearly lighter than remaining portions of head, forming a V-shaped pattern in dorsal view (vs. absence of a V-shaped pale area on predorsal region of body) and by presenting anterior portion of dorsal fin with conspicuous concentration of dark brown or black chromatophores, forming a dark patch (vs. dorsal fin uniformly colored, not forming dark patches or blotches); from C. burgessi and C. melanistius plus C. parallelus and C. surinamensis by having the anterior portion of dorsal-fin base with conspicuous concentration of dark brown or black chromatophores, forming a dark patch slightly darker than ground color of body (vs. dark patch on dorsal-fin base well defined, conspicuously standing out of the ground color of body). The new species can be further distinguished from C. burgessi, C. melanistius, C. oiapoquensis, C. parallelus, C. pavanelliae, C. polystictus, and C. surinamensis by having mosaic-like pattern of plates entirely or almost entirely covering ventral surface trunk (vs. mosaic-like pattern of plates restricted to some portions of ventral surface trunk, representing up to about 50% of its area).
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| Breeding pair (A), female on the left and male on the right, plus an ontogenetic series of Corydoras colossus (bred under aquarium conditions) showing general changes in external morphology and color pattern in specimens with (B) 9.0 mm TL, (C) 13.0 mm TL; (D) 17.0 mm TL, and (E) 22.0 mm TL. Photos by Hans Evers. |
Etymology. The specific epithet “colossus” derives from the Ancient Greek κολοσσός (kolossós), which means “large/giant statue”, alluding to the relatively large, robust, armored body of the new species. A noun in apposition.
Luiz Fernando Caserta Tencatt, Steven Grant and Rebecca Frances Bentley. 2023. A New color-changing Species of Corydoras (Siluriformes: Callichthyidae) from the rio Jutaí, Brazilian Amazon. Neotrop. ichthyol. 21(04); DOI: 10.1590/1982-0224-2023-0105
