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Ivor Hilton (2) Gert Blank (2) Mitsuhiro Iwamoto (2) Petr Posel (1)

Description: 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. Hypoptopoma gulare is distinguished from all congeners, with the exception of H. machadoi, by the presence of a single paranasal plate separating the lateral process of the lateral ethmoid from the second infraorbital and the nasal organ. In contrast, in all other species of Hypoptopoma, except H. steindachneri, the paranasal plates are absent and the lateral process of the lateral ethmoid contacts the second infraorbital. In H. steindachneri, there are two or more paranasal plates. Hypoptopoma gulare is distinguished from H. machadoi by a slender caudal peduncle (caudal-peduncle depth 7.2–9.1 (8.3) vs. 9.0– 12.0 (10.3); t (16.298) ,p , 0.001); by fewer premaxillary (12–16 (14) vs. 16–25 (20); t (12,675) ,p, 0.001) and dentary teeth (10–14 (12) vs. 14–21 (17); t (12,068),p, 0.001); by lanceolate plates at the base of the caudal fin with dark spot, asymmetrically shaped and slightly more extended over lower lobe branched rays, followed by two V-shaped bars pointing forward, with the anterior bar variably developed on the upper lobe but always connected at its angle with the basal spot (vs. the lanceolate plates at the base of the caudal fin with a light brown spot, symmetrically shaped and shortly extended over the branched rays, typically followed by three vertical bands variably defined, with the anterior band not continuous in the middle with the basal spot); by dorsal fin with dark brown, roughly triangular spot extended over base of anterior 3–4 branched rays, followed typically by 2–3 bars (vs. dorsal fin without triangular spot at base; dorsal fin typically with 4–7 bars). 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. Remarks: Cope (1878) described Hypoptopoma gulare based on a single specimen collected in 1877 near Pebas by Orton.

None

Hypoptopoma joberti, Otocinclus joberti

Loricariidae

South America: Upper Amazon River in Brazil; lower and upper Rio Ucayali. Type locality: Peruvian Amazon.

10.5cm. (4¼ins)

23-27°c (73-81°f.)

6.0-7.2.

Aquino, A.E. and S.A. Schaefer 2010 Systematics of the genus Hypoptopoma Günther, 1868 (Siluriformes, Loricariidae). Bull. Amer. Mus. Nat. Hist. 336:1-110.