226 

 dentaries thin, with relatively few, minute teeth. The small body size is shared 



among congeners only withal, brevis andA.piperatus. Distinguished fromyl. brevis 



by differences in pigmentation and a number of meristic counts (see diagnosis of A. 



brevis.). Separated from A. piperatus by the pigmentation pattern; presence of 



posterior caecae on the swimbladder; fewer anal-fin rays (23-30 versus 35-37); fewer 



pectoral-fin rays (7-9 versus 9-10); greater number of preanal vertebrae (17-19 



versus 15-16); greater number of branchiostegals (modally 8 versus 7); and, greater 



number of ribs (modally 7 versus 5). 



Description 



Morphometries and diagnostic meristic counts of the species are summarized 

 in Tables 11-12. Dorsal profile of head gently sloping to just behind orbits, then 

 angled upward in a straight line to dorsal fin origin. Ventral profile of head gently 

 curved. Skin on top of head thin, cranial bones moderately textured with ridges, 

 particularly on supraoccipital and nuchal plate. Mouth subterminal, the upper jaw 

 extending only slightly m front of lower jaw. Snout short (37-50% HL), forming a 

 broad arc in dorsal profile (Figs. 1, 6). Premaxillary tooth band crescentic, very 

 narrow and inflected posteriorly near corners of mouth; teeth relatively small and 

 villiform. Dentary tooth patch slightly broader than premaxillary band, recurved at 

 rictus of mouth. Eye large (X = 21% HL), covered by thick skin and invested by 

 opaque subepidermal fat deposits on anterior and posterior margins. Fontanelle 

 groove short, deep, bounded by relatively high ridges on central portion of frontals. 

 Anterior nares lateral to distal tip of mesethmoid wings and directed forward; 

 posterior nares remote, not bordering lateral margins of frontals, each with very 

 short flap of skin surrounding entire margin. Posterior tip of dentary reaching to 

 just below middle of eye. Gill membranes fused to isthmus behind plane through 



