Hemiarius

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 : 67-68

Hemiarius Bleeker, 1862

(fig. 57)

Hemiarius Bleeker, 1862: 7, 29. Type species: Cephalocassis stormii Bleeker, 1858. Type by original designation. Gender: masculine.

Diagnosis. Hemiarius can be distinguished from the remaining ariid genera by the combination of six characters shared with species of other genera of the family: (1) vomerine tooth plates present [shared with Aspistor , Bagre , Brustiarius , Cathorops dasycephalus , Cochlefelis , Galeichthys , Genidens (with exception of G. genidens ), Nemapteryx , Neoarius , Netuma , Notarius , Plicofollis (with exception of P. platystomus ), Potamosilurus (with exception of P. velutinus ) and Sciades ]; (2) frontal forming most of the bony bridge composed by this bone and the lateral ethmoid (shared with Amphiarius , Cathorops and Cephalocassis ); (3) transcapular process perpendicular to main axis of body (shared with Arius , Bagre , Batrachocephalus , Brustiarius , Carlarius , Cephalocassis , Cochlefelis , Doiichthys , Genidens , Ketengus , Nedystoma , Neoarius , Netuma , Osteogeneiosus , Plicofollis , Potamarius , Potamosilurus and Sciades ); (4) space between transcapular process and otic capsule moderately wide (shared with Arius , Aspistor , Bagre , Brustiarius , Carlarius , Cochlefelis , Doiichthys , Galeichthys , Genidens , Nedystoma , Neoarius , Netuma , Notarius , Plicofollis , Potamarius and Potamosilurus ); (5) contact face between transcapular process and basioccipital restricted and columnar [shared with Arius (with exception of A. gagora , A. maculatus and A. manillensis ), Batrachocephalus , Brustiarius , Carlarius , Cephalocassis , Cinetodus , Cochlefelis , Galeichthys , Genidens , Ketengus , Neoarius , Netuma , Osteogeneiosus , Pachyula , Plicofollis (with exception of P. platystomus ), Potamarius , Potamosilurus (with exception of P. latirostris ) and Sciades ]; (6) crest delimiting contact area between mesethmoid and premaxillary beginning at two thirds latero-anterior portion of former bone (shared with Arius , Bagre , Batrachocephalus , Cochlefelis , Nemapteryx , Netuma and Potamosilurus velutinus ).

Supplementary morphological characters. Cephalic shield granulated visible under the skin; lateral ethmoid and frontal delimiting a large fenestra visible under the skin; medial groove of neurocranium limited by frontal bones and/or on supraoccipital absent; posterior cranial fontanel well differentiated and oval shaped; 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 funnel shaped moderately long with posterior portion clearly narrower than its base; anterior and median nuchal plates fused and indistinct, forming a structure of semi-lunar aspect; tooth plates associated with vomer round; accessory tooth plates narrow and transversely elongate, bearing conical teeth; maxillary barbel fleshy and cylindrical; two pairs of mental barbels; base of adipose fin very long, as long as anal-fin base; lateral line not bifurcated at caudal region, reaching base of caudal-fin upper lobe; cleithrum narrow with second dorsal process on upper portion; posterior cleithral process short distinct from dorsal process of cleithrum.

Remarks. No specimen of H. hardenbergi (Kailola, 2000), H. harmandi Sauvage, 1880 and H. verrucosus (Ng, 2003) could be obtained for examination. The inclusion of the species in the genus is tentative and exclusively based on supplementary morphological characters, obtained from the literature.

Distribution and habitat. South and southeast Asia, predominantly brackish waters.