Osteogeneiosus Bleeker, 1846

(fig. 71)

Osteogeneiosus Bleeker, 1846: 173. Type species: Arius militaris Valenciennes, 1840 (= Silurus militaris Linnaeus, 1758). Type by subsequent designation by Bleeker (1862: 8; 1863: 93). Gender: Masculine.

Diagnosis. Osteogeneiosus can be differentiated from all other members of the Ariidae by the combination of the following exclusive (1 to 9) and shared (10 to 15) characters: (1) nasal anterior portion notably curved; (2) bony blade anteriorly connecting nasal tubules absent; (3) lachrymal with three anterior and one lateral branches (fig. 72); (4) maxillary thin and very elongate (fig. 73); (5) maxillary condyles very large (fig. 73); (6) palatine cylindrical very thick and short (fig. 74); (7) posterior cartilage of palatine vestigial; (8) metapterygoid low and elongate, its greatest depth three times in its length (fig. 75); (9) mental barbels absent; (10) vomer posterior process very thin from its base [shared with Plicofollis (with exception of P. tenuispinis and P. platystomus)]; (11) fenestra delimited by lateral ethmoid and frontal bones well developed (shared with Amphiarius, Cathorops, Cephalocassis, Cryptarius, Doiichthys, Hemiarius, Nedystoma and Nemapteryx); (12) mesial laminar projection on frontal bones absent (shared with Amphiarius, Arius, Aspistor, Cathorops, Cephalocassis, Cryptarius, Doiichthys, Galeichthys, Hemiarius, Nedystoma, Nemapteryx, Potamarius and Potamosilurus latirostris); (13) anterior cartilage of palatine short, less than 1/3 on bone length (fig. 74) (shared with Bagre and Galeichthys); (14) urohyal medial process short (shared with Galeichthys); (15) space limited by posterior epioccipital process and crests associated with fourth vertebra very reduced, restricted to anterior portion [shared with Arius, Carlarius, Brustiarius, Cochlefelis, Genidens, Neoarius, Netuma, Plicofollis (with exception of P. platystomus and P. tenuispinis), Potamarius grandoculis, Potamosilurus and Sciades (with exception of S. platypogon)].

Supplementary morphological characters. Cephalic shield granulated visible under the skin; a large 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 narrow, 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 longitudinally elongate, bearing molar-like teeth; maxillary barbel cylindrical and bony along its entire extension; base of adipose fin moderately long, about half as long as anal-fin base; lateral line bifurcated at caudal region, reaching base of caudal-fin upper and lower lobes; cleithrum wide, with second dorsal process on its upper portion; posterior cleithral process moderately long and distinct from second dorsal process of cleithrum.

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