This genus is recognised by
the flat head and large eyes that are set latterly
on the head and their heavy body armour. The ventral
region is also armored and you can sometimes identify
a species by the pattern on the underbelly. In saying
that the species in this genus are notoriously difficult
to identify and most of the time you would need the
location of the catchment area or even down to the
river itself to pinpoint a certain species. Description:
Vertebrae: 27. This species is distinguished from
its congeners by having a non-pigmented band on the
head positioned parallel to the ventral margin of
the rostral and lateral snout plates and with the
margin between pigmented and non-pigmented plates
very well defined (vs. absence of a distinct pigmented.
It can be further distinguished from its congeners,
except for H.
by having the ventral surface of the anterior rostral
plate as wide as the ventral surface of the first
lateral rostral plates (vs. ventral surface gradually
widening from anterior rostral to lateral rostral
plates). It is readily distinguished from H. inexspectatum
by having a greater number of plates along the trunk
medial series 23 (vs. 20-21 (21)), by having the snout
appearing pointed in dorsal view due to a slight concavity
between rostral plate and first infraorbital (vs.
snout typically spatulate), and by having, if present,
a distinct series of odontodes along dorsal and ventral
rostral margin of snout restricted to the anterior
rostral plate (vs. series of odontodes along dorsal
and ventral rostral margin of snout extended laterally
to include second and third infraorbitals). Sexual
Differences: Male urogenital papilla short
and conical, covered by anterior flaplike anus. Males
with patch of tightly arranged small odontodes, variably
covering first to fourth plates of ventral series,
lateral to urogenital papilla. Males with poorly developed
soft-tissue flap along posterior margin of pelvic
spine. Female anus tubular, without separate urogenital
papilla. In females, size and arrangement of odontodes
on plates lateral to anus similar to adjacent plates,
without distinct patch of differentially arranged
odontodes. Female pelvic spine without flap of soft
tissue on posterior surface.
Lower Rio Tapajos and lower Rio Trombetas. Type
locality: Rio Tapajos, Itaituba, Pará
Aquino, A.E. and S.A.
Systematics of the genus Hypoptopoma Günther,
1868 (Siluriformes, Loricariidae). Bull. Amer. Mus.
Nat. Hist. 336:1-110 Froese, R. and D. Pauly. Editors.
2017. FishBase. World Wide Web electronic publication.
www.fishbase.org, ( 10/2017 ). Grant, Steven. pers comm.