Potamarius

Alexandre P. Marceniuk & Naércio A. Menezes, 2007, Systematics of the family Ariidae (Ostariophysi, Siluriformes), with a redefinition of the genera., Zootaxa 1416, pp. 1-126: 96-98

publication ID

z01416p001

publication LSID

lsid:zoobank.org:pub:FFC65592-D8DB-41BE-AEAC-A41EAB6C6185

persistent identifier

http://treatment.plazi.org/id/3A1CA07A-1945-B868-42C1-D59184489B32

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Thomas

scientific name

Potamarius
status

 

Potamarius  ZBK  Hubbs & Miller, 1960

(Fig. 84)

Potamarius  ZBK  Hubbs & Miller, 1960: 101. Type species: Conorhynchos nelsoni  ZBK  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  ZBK  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  ZBK  (with exception of A. caelatus  ZBK  and A. madagascariensis  ZBK  ), Cathorops  , Cephalocassis  ZBK  , Cinetodus  ZBK  , Ketengus  ZBK  , Osteogeneiosus  ZBK  and Pachyula  ZBK  ]; (5) lateral horn of lateral ethmoid very long and pointing backward (fig. 87) [shared with Arius  ZBK  (with exception of Arius caelatus  ZBK  ), Doiichthys  ZBK  and Plicofollis  ZBK  (with exception of P. platystomus  and Plicofollis tenuispinis  )]; (6) anterior portion of vomer acute and conspicuous [shared with Amphiarius  , Arius  ZBK  , Aspistor  ZBK  , Cephalocassis  ZBK  , Cinetodus  ZBK  , Osteogeneiosus  ZBK  , Plicofollis  ZBK  , Notarius  ZBK  (with exception of N. planiceps  ), Pachyula  ZBK  and Potamosilurus macrorhynchus  ]; (7) vomerine tooth plate absent [shared with Amphiarius  , Arius  ZBK  , Batrachocephalus  ZBK  , Carlarius  , Cathorops  (with exception of C. dasycephalus  ), Cephalocassis  ZBK  , Cinetodus  ZBK  , Cryptarius  ZBK  , Doiichthys  ZBK  , Genidens genidens  , Ketengus  ZBK  , Nedystoma  ZBK  , Osteogeneiosus  ZBK  , Pachyula  ZBK  , Plicofollis platystomus  and Potamosilurus velutinus  ]; (8) frontal bones without mesial laminar projection (fig. 87) (shared with Amphiarius  , Arius  ZBK  , Aspistor  ZBK  , Cathorops  , Cephalocassis  ZBK  , Cryptarius  ZBK  , Doiichthys  ZBK  , Galeichthys  ZBK  , Hemiarius  ZBK  , Nedystoma  ZBK  , Nemapteryx  ZBK  , Osteogeneiosus  ZBK  and Potamosilurus latirostris  ); (9) orbitosphenoid without lateral expansion [shared with Amphiarius  , Aspistor  ZBK  , Bagre  , Batrachocephalus  ZBK  , Cathorops  , Cephalocassis  ZBK  , Cochlefelis  ZBK  , Cryptarius  ZBK  , Doiichthys  ZBK  , Galeichthys  ZBK  , Hemiarius  ZBK  , Ketengus  ZBK  , Nedystoma  ZBK  , Nemapteryx  ZBK  , Neoarius  ZBK  , Osteogeneiosus  ZBK  , Notarius  ZBK  (with exception of N. planiceps  ), Pachyula  ZBK  , Plicofollis platystomus  , Potamosilurus latirostris  , Sciades couma  , S. emphysetus  ZBK  , S. passany  , S. proops  , S. seemanni  and S. sagor  ]; (10) parasphenoid wing-like process absent (shared with Batrachocephalus  ZBK  , Cephalocassis  ZBK  , Cryptarius  ZBK  , Doiichthys  ZBK  , Ketengus  ZBK  , Nedystoma  ZBK  , Nemapteryx  ZBK  and Osteogeneiosus  ZBK  ); (11) premaxillary almost as long as wide (shared with Cathorops  , Cephalocassis  ZBK  and Cinetodus  ZBK  ); (12) metapterygoid 1.5 times as long as high [shared with Cathorops  (with exception of Cathorops dasycephalus  ), Cephalocassis  ZBK  , Cinetodus  ZBK  , Cryptarius  ZBK  , Pachyula  ZBK  and Plicofollis  ZBK  ]; (13) metapterygoid anterior process truncate [shared with Cinetodus  ZBK  , Cochlefelis  ZBK  , Pachyula  ZBK  , Plicofollis  ZBK  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  ZBK  ); (15) third basibranchial in form of a long and thin hourglass (shared with Cochlefelis  ZBK  and Galeichthys  ZBK  ); (16) number of ribs equal to or less than 14 (shared with Amphiarius  , Arius  ZBK  , Aspistor  ZBK  , Batrachocephalus  ZBK  , Brustiarius  ZBK  , Cathorops  , Cephalocassis  ZBK  , Cinetodus  ZBK  , Cryptarius  ZBK  , Doiichthys  ZBK  , Galeichthys  ZBK  , Hemiarius  ZBK  , Ketengus  ZBK  , Nedystoma  ZBK  , Nemapteryx  ZBK  , Osteogeneiosus  ZBK  , Pachyula  ZBK  , 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  ZBK  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.