Cathorops

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 : 38-40

Cathorops Jordan & Gilbert, 1882

(fig. 30)

Cathorops Jordan & Gilbert, 1882: 39. Type species: Arius hypophthalmus Steindachner, 1876. Type by original designation and also monotypy. Originally a subgenus of Arius . Gender: masculine.

Diagnosis. Cathorops can be diagnosed by an extensive list of exclusive (1 to 6) and shared (7 to 18) characters: (1) transcapular process depressed; (2) otic capsules similar, very little differentiated from each other; (3) bony crest on posterior portion of basioccipital folded over exoccipital; (4) lateral process of basioccipital very long (fig. 31); (5) anterior edge of subvertebral process keeled (fig. 31); (6) opening of aortic canal inside base of occipital process (fig. 31); (7) posterior branches of mesethmoid thin (fig. 32) [shared with Bagre (with exception of B. panamensis ), Cephalocassis , Doiichthys , Ketengus , Nedystoma and Nemapteryx ]; (8) posterior branches of mesethmoid parallel along entire extension (fig. 32) (shared with Cephalocassis , Doiichthys , Ketengus , Nedystoma and Nemapteryx ); (9) frontal bone contributing with two thirds to the formation of bony bridge between this bone and lateral ethmoid (fig. 32) (shared with Amphiarius , Cephalocassis and Hemiarius ); (10) extrascapular subtriangular (fig. 32) (shared with Cinetodus ); (11) end of subvertebral process in form of spatula (shared with Cephalocassis , Doiichthys , Hemiarius , Nedystoma and Nemapteryx ); (12) premaxillary narrow, almost as long as wide (shared with Cephalocassis , Cinetodus and Potamarius ); (13) anterior edge of opercle straight (fig. 33) [shared with Plicofollis (with exception of P. platystomus )]; (14) posterior edge of interopercle angulated (fig. 33) [shared with Plicofollis (with exception of P. platystomus )]; (15) upper crest of hyomandibular short and high (shared with Amphiarius , Arius , Aspistor , Batrachocephalus , Hemiarius , Ketengus , Nedystoma , Notarius , Osteogeneiosus , Plicofollis platystomus and Potamosilurus ); (16) inferior crest of hyomandibular absent (shared with Cephalocassis and Ketengus ); (17) urohyal anterior margin not notched (shared with Batrachocephalus and Plicofollis platystomus ); (18) superficial ventral ossification convexly rounded (shared with Cephalocassis borneensis ).

The definition of Cathorops is also supported by exclusive (1 to 4) and shared (5 to 12) characters absent only in Cathorops dasycephalus : (1) mesethmoid and lateral ethmoid delimiting a small fenestra (fig. 32); (2) more than three fifths of the temporal fossa formed by extrascapular (fig. 32); (3) females with molariform dentary teeth sometimes present in males; (4) cardinal veins passing beside the aortic channel; (5) mesethmoid posterior horn tubular and very thin (fig. 32) (shared with Ketengus ); (6) mesethmoid posterior branches very long, more than half as long as cranial fontanel (fig. 32) (shared with Nemapteryx ); (7) posterior cranial fontanel reduced to a small hole (fig. 32) [shared with Bagre , Brustiarius , Galeichthys , Genidens , Netuma and Plicofollis (with exception of P. platystomus )]; (8) posterior cranial fontanel limited by frontal bones (fig. 32) (shared with Bagre , Brustiarius , Carlarius , Galeichthys , Genidens , Netuma , Osteogeneiosus , Plicofollis , Potamarius and Sciades platypogon ); (9) a very restricted area for insertion of gill rakers on fifth ceratobranchial (shared with Batrachocephalus , Doiichthys , Ketengus and Nedystoma ); (10) second hypobranchial transversely elongate with its mesial edge acute (fig. 34) (shared with Cephalocassis , Doiichthys and Nedystoma ); (11) anterior process of first hypobranchial very pronounced (fig. 34) (shared with Cephalocassis , Doiichthys and Nedystoma ); (12) posterior cleithral process very short, (fig. 35) (shared with Cephalocassis , Doiichthys , Hemiarius , Nedystoma and Nemapteryx ).

Supplementary morphological characters. Cephalic shield granulated visible under the skin; lateral ethmoid and frontal limiting a wide fenestra very conspicuous visible under the skin (except in C. dasycephalus ); medial groove of neurocranium very distinct, limited by frontal bones and/or on supraoccipital; posterior cranial fontanel very reduced (except in C. dasycephalus ); fenestra limited by supraoccipital, pterotic and sphenotic absent; fossa limited by pterotic, supracleithrum and extrascapular very reduced; epioccipital not invading dorsal portion of cephalic shield; occipital process funnel shaped moderately long, its posterior part considerably narrower than its base; anterior and median nuchal plates fused and indistinct, forming a structure of semi-lunar aspect; vomerine tooth plates absent (except in C. dasycephalus ); accessory tooth plates small, oval and perpendicularly disposed, bearing molar-like teeth (except in C. dasycephalus ); maxillary barbel fleshy and cylindrical; two pairs of mental barbels; base of adipose fin very short, less than one-half length of anal-fin base; lateral line not bifurcated at caudal region, reaching base of caudal-fin upper lobe; cleithrum thin with second dorsal process on its upper portion; posterior cleithral process short (except in C. dasycephalus ) and distinct from second dorsal process of cleithrum.

Remarks. The inclusion of C. steindachneri (Gilbert & Starks, 1904) was based on examination of external morphological characters obtained from the literature.

Distribution and habitat. Eastern and western Central and South America, brackish and freshwater.