Acestrocephalus Eigenmann, 1909

Menezes, Naércio A., 2006, Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae), Neotropical Ichthyology 4 (4), pp. 385-400 : 386-387

Acestrocephalus Eigenmann, 1909

Acestrocephalus Eigenmann, 1910:447 . Type species: Xiphorhamphus anomalus Steindachner, 1880 . Type by original designation. Gender: masculine.

Diagnosis. Acestrocephalus can be distinguished from the remaining genera of the Characinae sensu Lucena & Menezes (2003) by the following unique combination of morphological characters extracted from Menezes (1976: 37) with the addition of new ranges of meristic and morphometric characters for the genus due to the values of the new species described herein.

Body comparatively small (SL 31.4-135 mm); anterior dorsal region not elevated; dorsal body profile regularly curved from tip of snout to caudal base; lower part of antorbital only in contact with maxilla; first infraorbital relatively short, high on its median part; nasal bone tubular; cleithrum not notched, just with a slight sinuosity along its ventral edge; ectopterygoid with a median ventral bony crest; supraoccipital spine short; dentary with two rows of teeth, anterior teeth of external row much larger than posterior ones; first and third anterior teeth canine-like, more developed than the other two; posterior dentary tooth row with 20-40 small conical teeth slightly curved posteriorly, their number tending to increase with an increase in standard length; inner row of teeth on dentary formed by 7-14 small conical teeth; scales comparatively large and numerous, perforated lateral-line scales 67-79, 10-15 above and 9-13 below lateral line; anal fin comparatively short, with iv-v,25-36 rays, its origin situated on vertical line always crossing behind middle of dorsal-fin base length; pectoral fin with i,11-16 rays.

Key to species of Acestrocephalus

1. A black spot at humeral region slightly posterior and dorsal to pseudotympanum, very small and sometimes indistinct in very young specimens.....................................................2

1’.No black spot at humeral region ......................................... 4

2. Horizontal scale rows around caudal peduncle 24-25; 10-12 small conical teeth between first and last larger conical teeth in the external premaxillary tooth row; 75-78 lateral line scales ........................................................... A. boehlkei

2’.Horizontal scale rows around caudal peduncle 22-23; 7-9 small conical teeth between first and last larger conical teeth in the external premaxillary tooth row; 70-74 lateral line scales ............................................................................... 3

3. Branched anal-fin rays 25-27; 7-8 developed gill-rakers on first branchial arch; 22-29 small conical teeth in posterior dentary tooth row ........................................... A. maculosus

3’.Branched anal-fin rays 29-31; 5-6 developed gill-rakers on first branchial arch; 33-37 small conical teeth in posterior dentary tooth row ............................................ A. stigmatus

4. A triangular dark blotch on caudal base anteriorly continuous with dark longitudinal stripe approximately on midbody in freshly preserved specimens; 40-46 maxillary teeth ......... 5

4’.Dark blotch on caudal base absent or oblong, oval-shaped, anteriorly continuous with dark longitudinal stripe; 24-38 maxillary teeth ....................................................................... 6

5. Horizontal scale rows around caudal peduncle 20-22; 10-12 horizontal scale rows above lateral line, 10-12 below lateral line ......................................................................... A. sardina

5’.Horizontal scale rows around caudal peduncle 23-24; 13-14 horizontal scale rows above lateral line, 12-13 below lateral line ............................................................... A. nigrifasciatus

6. Caudal-fin base with few scattered dark chromatophores never forming a conspicuous dark blotch ....... A. pallidus

6’. Caudal-fin base with oblong dark blotch, conspicuous and continuous with longitudinal dark stripe on body .......... 7

7. Posterior dentary tooth row with 23-28 teeth; 8-11 small conical teeth in external tooth row on premaxilla; 9-11 inner dentary teeth ..................................................... A. anomalus

7’.Posterior dentary tooth row with 28-36 teeth; 6-8 small conical teeth in external tooth row on premaxilla; 10-13 inner dentary teeth .......................................................... A. acutus