Potamarius
Creators: name: Alexandre P. Marceniuk
name: Naércio A. Menezes
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Siluriformes
Ariidae
Potamarius

description: Potamarius Hubbs & Miller, 1960
(Fig. 84)
Potamarius Hubbs & Miller, 1960: 101. Type species: Conorhynchos nelsoni Evermann & Goldsborough, 1902. Type by original designation. Gender: masculine.
Diagnosis. The following combination of exclusive (1 to 3) and shared (4 to 14) characters distinguishes Potamarius from the remaining ariid genera: (1) optic foramen very large; (2) interopercle subrectangular (fig. 85); (3) lateral processes of urohyal completely free from bony blade contacting medial process of the bone (fig. 86); (4) mesethmoid median portion thin (fig. 87) [shared with Arius (with exception of A. caelatus and A. madagascariensis), Cathorops, Cephalocassis, Cinetodus, Ketengus, Osteogeneiosus and Pachyula]; (5) lateral horn of lateral ethmoid very long and pointing backward (fig. 87) [shared with Arius (with exception of Arius caelatus), Doiichthys and Plicofollis (with exception of P. platystomus and Plicofollis tenuispinis)]; (6) anterior portion of vomer acute and conspicuous [shared with Amphiarius, Arius, Aspistor, Cephalocassis, Cinetodus, Osteogeneiosus, Plicofollis, Notarius (with exception of N. planiceps), Pachyula and Potamosilurus macrorhynchus]; (7) vomerine tooth plate absent [shared with Amphiarius, Arius, Batrachocephalus, Carlarius, Cathorops (with exception of C. dasycephalus), Cephalocassis, Cinetodus, Cryptarius, Doiichthys, Genidens genidens, Ketengus, Nedystoma, Osteogeneiosus, Pachyula, Plicofollis platystomus and Potamosilurus velutinus]; (8) frontal bones without mesial laminar projection (fig. 87) (shared with Amphiarius, Arius, Aspistor, Cathorops, Cephalocassis, Cryptarius, Doiichthys, Galeichthys, Hemiarius, Nedystoma, Nemapteryx, Osteogeneiosus and Potamosilurus latirostris); (9) orbitosphenoid without lateral expansion [shared with Amphiarius, Aspistor, Bagre, Batrachocephalus, Cathorops, Cephalocassis, Cochlefelis, Cryptarius, Doiichthys, Galeichthys, Hemiarius, Ketengus, Nedystoma, Nemapteryx, Neoarius, Osteogeneiosus, Notarius (with exception of N. planiceps), Pachyula, Plicofollis platystomus, Potamosilurus latirostris, Sciades couma, S. emphysetus, S. passany, S. proops, S. seemanni and S. sagor]; (10) parasphenoid wing-like process absent (shared with Batrachocephalus, Cephalocassis, Cryptarius, Doiichthys, Ketengus, Nedystoma, Nemapteryx and Osteogeneiosus); (11) premaxillary almost as long as wide (shared with Cathorops, Cephalocassis and Cinetodus); (12) metapterygoid 1.5 times as long as high [shared with Cathorops (with exception of Cathorops dasycephalus), Cephalocassis, Cinetodus, Cryptarius, Pachyula and Plicofollis]; (13) metapterygoid anterior process truncate [shared with Cinetodus, Cochlefelis, Pachyula, Plicofollis and Potamosilurus (with exception of P. velutinus)]; (14) distance from optic foramen and trigeminofacial complex equal to width of complex (shared with Bagre and Galeichthys); (15) third basibranchial in form of a long and thin hourglass (shared with Cochlefelis and Galeichthys); (16) number of ribs equal to or less than 14 (shared with Amphiarius, Arius, Aspistor, Batrachocephalus, Brustiarius, Cathorops, Cephalocassis, Cinetodus, Cryptarius, Doiichthys, Galeichthys, Hemiarius, Ketengus, Nedystoma, Nemapteryx, Osteogeneiosus, Pachyula, Plicofollis platystomus and Potamosilurus).
Supplementary morphological characters. Cephalic shield granulated visible under the skin; a moderately developed fenestra limited by lateral ethmoid and frontal visible under the skin; medial groove of neurocranium very distinct, limited by frontal bones and/or on supraoccipital; posterior cranial fontanel moderately developed, long and narrow; fenestra limited by supraoccipital, pterotic and sphenotic absent; fossa limited by pterotic, supracleithrum and extrascapular relatively large; epioccipital not invading dorsal portion of cephalic shield; occipital process triangular, moderately long and wide, progressively narrower toward its posterior part; anterior and median nuchal plates fused and indistinct, forming a structure of semi-lunar aspect; tooth plates associated with vomer absent; accessory tooth plates absent or rudimentary; maxillary barbel fleshy and cylindrical; base of adipose fin moderately long, about half as long as anal-fin base; lateral line not bifurcated at caudal region, reaching base of caudal-fin upper lobe; cleithrum wide, with second dorsal process on its upper portion; posterior cleithral process of moderate length, distinct from second dorsal process of cleithrum.
Remarks. The type-species of the genus, Conorhynchos nelsoni Evermann & Goldsborough, 1902 was characterized on the basis of characters observed in preserved specimens and data from the literature.
Distribution and habitat. Central and South America, freshwater.
description: Published as part of Alexandre P. Marceniuk & Naércio A. Menezes, 2007, Systematics of the family Ariidae (Ostariophysi, Siluriformes), with a redefinition of the genera., pp. 1-126 in Zootaxa 1416 on pages 96-98