Classification / Names
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Teleostei (teleosts) >
Characiformes (Characins) >
Characidae (Characins; tetras) > Stethaprioninae
Etymology: Hemigrammus: Greek, hemi = half + Greek, gramma = letter, signal (Ref. 45335); diagonicus: Name from Latin diagonicus, meaning diagonal, referring to the position of the blotch on the caudal fin, unique among the species of Hemigrammus.
Environment: milieu / climate zone / depth range / distribution range
Ecology
Freshwater; benthopelagic. Tropical; 2°S - 3°S, 55°W - 57°W
South America: Brazil.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 2.8 cm SL male/unsexed; (Ref. 87304)
Short description
Identification keys | Morphology | Morphometrics
Hemigrammus diagonicus can be easily differentiated from its congeners, except for Hemigrammus silimoni, by the presence of a blotch on the caudal fin restricted to the dorsal lobe (vs. no blotches on the caudal fin, blotches restricted to the base of the rays, or blotches arranged symmetrically in dorsal and ventral lobes). Hemigrammus diagonicus is distinguished from H. silimoni by the autapomorphic presence of the caudal-fin blotch shaped like a bar that extends diagonally from the base of the median rays to the end of the upper lobe rays (vs. conspicuous ocellus like blotch on the lower region of the caudal-fin dorsal lobe); height of dorsal fin 22.3–30.2% SL (vs. 31.0–37.4% SL); length of anal-fin base 24.0–28.0% SL (vs. 28.7–31.5% SL); horizontal eye diameter 33.8–41.3% HL (vs. 43.4– 48.1% HL) (Ref. 87304).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Mendonça, M.B. and W.B. Wosiacki, 2011. A new species of Hemigrammus from the Lower Amazon Floodplain (Characiformes: Characidae). Copeia 2011(2):211-215. (Ref. 87304)
IUCN Red List Status (Ref. 130435: Version 2024-2)
Threat to humans
Harmless
Human uses
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Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00955 (0.00428 - 0.02132), b=3.12 (2.93 - 3.31), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref.
93245).
Trophic level (Ref.
69278): 3.0 ±0.4 se; based on size and trophs of closest relatives
Fishing Vulnerability (Ref.
59153): Low vulnerability (10 of 100).