Comprehensive DescriptionRead full entry
Diagnosis. Aspistor ZBK can be diagnosed by the following combination of exclusive (1 to 4) and shared characters(5 to 13): (1) tooth plates associated with vomer usually fused as a single large plate, indistinct in adult specimens; (2) bony blade associated with urohyal medial process approximately of same width for its entire length (fig. 11); (3) anterior and median nuchal plates forming a well developed butterfly shaped structure (fig. 12); (4) anterior margin of nuchal plate slightly concave (fig. 12); (5) lateral processes of vomer very wide (shared with Arius ZBK , Bagre , Batrachocephalus ZBK , Cinetodus ZBK , Galeichthys ZBK , Nemapteryx ZBK , Notarius planiceps , Osteogeneiosus ZBK , Pachyula ZBK , Plicofollis tenuispinis , Plicofollis platystomus , Potamosilurus and Sciades ); (6) accessory tooth plates longitudinally elongate, anteriorly wide and becoming progressively narrower toward its posterior part [shared with Arius ZBK (with exception of A. caelatus ZBK , A. dispar ZBK and A. madagascariensis ZBK ), Osteogeneiosus ZBK and Plicofollis ZBK ]; (7) accessory tooth plates ventral to orbitosphenoid and metapterygoid [shared with Arius ZBK (with exception of A. caelatus ZBK and A. madagascariensis ZBK ), Osteogeneiosus ZBK and Plicofollis ZBK ]; (8) accessory tooth plates bearing molariform teeth [shared with Arius ZBK (with exception of A. caelatus ZBK and A. madagascariensis ZBK ), Batrachocephalus ZBK , Cathorops (with exception of C. dasycephalus ), Osteogeneiosus ZBK and Plicofollis ZBK ]; (9) epioccipital dorsally exposed (fig. 12) [shared with Amphiarius rugispinis , Carlarius , Cinetodus ZBK , Pachyula ZBK and Plicofollis ZBK (with exception of P. platystomus and P. tenuispinis )]; (10) posterior margin of occipital process convex (fig. 12) (shared with Sciades proops ); (11) nuchal plate overlaying occipital process (shared with Notarius troschelii , Sciades emphysetus ZBK and S. proops ); (12) lateral processes of urohyal, half as long medial process (fig. 11) (shared with Arius ZBK , Batrachocephalus ZBK , Cathorops , Cephalocassis borneensis , Cinetodus ZBK , Genidens ZBK , Ketengus ZBK , Osteogeneiosus ZBK , Nedystoma ZBK , Nemapteryx ZBK , Netuma thalassinus and Pachyula ZBK ); (13) posterior portion of second basibranchial very short and robust (fig. 13) (shared with Arius gagora , A. maculatus ZBK and Plicofollis ZBK ).
Supplementary morphological characters. Cephalic shield granulated visible under the skin; a moderately developed fenestra limited by frontal and lateral ethmoid bones visible under the skin; medial groove of neurocranium limited by frontal bones and/or on supraoccipital absent; posterior cranial fontanel oval, clearly differentiated; fenestra limited by supraoccipital, pterotic and sphenotic absent; fossa limited by pterotic, supracleithrum and extrascapular relatively large; epioccipital invading into dorsal portion of cephalic shield; occipital process very short and wide at base, round shaped; anterior and median nuchal plates fused and indistinct, forming a butterfly shaped large structure; vomerine tooth plates absent; accessory tooth plates longitudinally elongated, with molar-like 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 wide, with a second dorsal process on its upper portion; posterior cleithral process moderately long and distinct from second dorsal process of cleithrum.
Distribution and habitat. North and eastern South America, marine and brackish waters.