Petrocephalus petersi

General description: 

Original description from Kramer et al (2012):

Body round-oval shape. Head broadly rounded with a small ventrally positioned subterminal mouth, situated ventral to the eye; head and body dorsolaterally compressed. Dorsal fin (a) origin situated about two-thirds of standard length from snout, (b) obliquely orientated, anteriorly higher and posteriorly lower, (c) distal margin crescentic with anterior two or three rays longer than posterior rays, and (d) number of rays 18 (n = 2), 19 (n = 2), 20 (n = 7). Anal fin (a) longer than dorsal fin, (b) opposite dorsal fin with slightly more anterior origin, (c) obliquely orientated, anteriorly lower and posteriorly higher, (d) anterior 10 or so rays longer than posterior ones, especially in males where they also appear stronger, (e) margin broadly rounded, (f) rays posterior to first 10 with distal margin straight, (g) number of rays 25 (n = 4), 26 (n = 7). Forked tail fin with rounded lobes. Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fins (beyond pelvics). Scales on caudal peduncle circumference, 12 (n = 1), 13 (n = 1), 14 (n = 2), 15 (n = 1), 16 (n = 6). Caudal peduncle slender, subcylindrical entire length, usually 19.7% (18.5–20.8%) of SL. Males with kink in anal fin base, which is absent in juveniles and females where the anal fin base is straight.

Colour in preservation: light beige.

Diagnostic description: 

From Kramer et al (2012):

Preanal length, PAL, mean 0.616 (range 0.595–0.637) of SL; predorsal length, PDL, mean 0.642 (range 0.623–0.658) of SL; length of snout to centre of eye, LSc, mean 0.364 (range 0.345–0.383) of HL, head length; length of snout to poste- rior orbital rim of eye, LSo, mean 0.462 (range 0.442–0.479) of HL, head length; body depth, BD, mean 0.299 (range 0.287–0.323) of SL; number of scales around caudal peduncle, SPc, median 16 (range 12–16).

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith