Morphology Data of Hypoptopoma steindachneri
Identification keys
Main Ref. Aquino, A.E. and S.A. Schaefer, 2010
Appearance refers to
Bones in OsteoBase

Sex attributes

Specialized organs
Different appearance
Different colors
Remarks Male urogenital papilla pointed, variably joined to anterior flaplike anus; with patch of tightly arranged small odontodes oriented as a swirl, variably covering first to fourth plates of ventral series, lateral to urogenital papilla. Female anus tubular, without separate urogenital papilla; size and arrangement of odontodes on plates lateral to anus similar to adjacent plates, without distinct patch of differentially arranged odontodes (Ref. 84367).

Descriptive characteristics of juvenile and adult

Striking features
Body shape lateral elongated
Cross section
Dorsal head profile
Type of eyes
Type of mouth/snout
Position of mouth
Type of scales

This species is distinguished from its congeners by having two or more paranasal plates between the pararostral plates and the second infraorbital (vs. a single paranasal plate in H. gulare and H. machadoi or paranasal plates absent); by having a single plate between the canal-bearing plate and the first, second, and third infraorbitals (vs. two plates); by having the canal-bearing plate subdivided into a smaller plate along the anteromedial margin and the larger posterior portion that bears the canal (vs. a single, undivided canal-bearing plate); by having the basipterygium constricted laterally, the interpelvic distance 2.0-6.4 (5.1) (vs. > 6.5); by having the anterodorsal basipterygium lamina that forms the channel for the pelvic arrector muscles extended anteriorly beyond the lateral basipteryigium process (vs. anterodorsal basipterygium lamina not extended beyond lateral basipterygium process); by having the tips of the caudal-fin rays darkly pigmented, forming a vertical band along the fin margin (vs. tips of not uniformly dark, not forming a vertical band along posterior margin). It is further distinct from all congeners, except for H. brevirostratum, by mature males having a membranous outgrowth between pelvic spine and first pelvic-fin branched ray (vs. no membranous

outgrowth) (Ref. 84367).

Ease of Identification

Meristic characteristics of Hypoptopoma steindachneri

Lateral Lines Interrupted: No
Scales on lateral line
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line
Scale rows below lateral line
Scales around caudal peduncle
Gill clefts (sharks/rays only)
Gill rakers
on lower limb
on upper limb
total 26 - 26


Dorsal fin(s)

Fins number
Finlets No. Dorsal   
Spines total
Soft-rays total
Adipose fin

Caudal fin


Anal fin(s)

Fins number
Spines total
Soft-rays total

Paired fins

Pectoral Attributes  
Pelvics Attributes  
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
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