All FishesAuchenipteridaeAuchenipterinaeAgeneiosus

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Scientific Name Ageneiosus marmoratus  Eigenmann, 1912
Common Name Jaguar Dolphin Catfish
Type Locality Creek below Potaro Landing, Guyana.
Pronunciation ah genie OH sus - MAR mo rat us
Etymology Ageneiosus, from the Greek a, meaning without and genias, meaning beard in reference to the apparent lack of barbels. In fact, catfish of this genus have very short maxillary barbels that are almost indistinguishable to the human eye. 
Hop to next section Species Information
Size 185mm or 7.3" SL. Find near, nearer or same sized spp.
Identification Ageneiosus differs from other Auchenipteridae, except Tympanopleura, by having: 1, long bony process, narrowing distally on anterolateral border of sphenoid; 2, longitudinal groove on posterior margin of anterior fontanel (also present in Pseudepapterus); 3, dorsal portion of posttemporal-supracleithrum divided into two prominent branches; 4, internal and external processes of epioccipital sutured to parapophyses of fifth and sixth vertebrae; 5, bony process on posteromedial border of first infraorbital bone (also present in Tetranematichthys); 6, anterior or posterior region of second infra-orbital very curved; 7, bony expansion on laterodorsal margin of premaxilla; 8, operculum with spongy ossification; 9, bone projections on posterior extreme of the parurohyal; 10, seventh vertebra not fused to complex vertebrae (also present in Pseudepapterus); 11, well-developed crown of spines in proximal region of anterior margin of dorsal-fin spine of mature males; 12, short maxillary barbel, not extending posteriorly beyond snout (also present in Tetranematichthys); 13, mental barbels absent; 14, bony spines on maxillary barbel of mature males; 15, posterior lobes of testes reduced or absent (also present in Auchenipterus). Ageneiosus differs from Tympanopleura by having: 1, reduced and completely ossified gas bladder in adults, except Ageneiosus pardalis Lütken 1874 (v. large, non-ossified gas bladder during all phases of ontogenetic development); 2, posterior diverticula on the gas bladder absent (v. having paired posterior diverticula on the gas bladder, except T. piperata); 3, epaxial muscles almost completely covering the tympanic region in adults, except A. pardalis (v. tympanic region translucent, not covered by epaxial muscles); 4, dorsal process on the base of pectoral fin weakly developed, loosely articulating with cleithrum (v. dorsal process on the base of pectoral fin well developed, strongly articulating with cleithrum); 5, fenestra on the lateral wall of cleithrum (v. lateral wall of cleithrum completely ossified).

A key to the species of Ageneiosus is located here.

A. marmoratus exhibits the lipstick-like margin around the mouth, a marmorated colouration on the sides (juveniles have much greater contrast of pattern) and the gray margin in the adipose is broader than in A. inermis which also has a slight margin. Also in contrast to A. inermis, A. marmoratus has a more rounded shape of the tips of the caudal fin.
Sexing Unknown
Hop to next section Habitat Information
Distribution South America.
Guyana Waters, Coastal Rivers of Guyanas (click on these areas to find other species found there)
Orinoco (click on these areas to find other species found there)

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IUCN Red List Category Not Evaluated
pH 6.0 - 7.0
Temperature 23.0-26.0°C or 73.4-78.8°F (Show species within this range)
Hop to next section Husbandry Information
Breeding Unreported in the aquarium.
Breeding Reports There is no breeding report.
Hop to next section Further Information
Reference Mem. Carnegie Mus.v. 5 (no. 1) - pp206 - Pl. 22 (fig. 1)
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Last Update 2020 Sep 20 04:34 (species record created: 2005 Jul 19 00:00)