Petrocephalus haullevillii Boulenger, 1912 (resurrected species) (Figure 2, nos 24, 26) Petrocephalus haullevillii Boulenger, 1912: 5. Petrocephalus stuhlmanni haullevillii: David and Poll 1937: 200 (spelt haullevillei). Petrocephalus catostoma haullevillii: Whitehead and Greenwood 1959: 286. Type specimens. Syntypes: BMNH 1912.4.1.181–183 (3), BMNH 1912.4.1.184–185 (2), BMNH 1912.4.1.186–188 (3), MRAC 1496–1501 (6) (all studied); ZMB 18795 (1), ANSP 38586–88 (3) (not studied). Type locality. “ Chiloanga [River] at Mayili, Luali [River] at Lundo and in the Luculla [River]”, Lower Congo. Diagnosis. Predorsal length, PDL, mean 0.618 (range 0.605 –0.641) of SL; preanal length, PAL, mean 0.564 (range 0.542 –0.586) of SL; dorsal fin length, LD, mean 0.168 (range 0.154 –0.177) of SL; anal fin length, LA, mean 0.254 (range 0.24–0.269) of SL; distance dorsal fin origin to end of caudal peduncle, pD, mean 0.421 (range 0.401–0.44) of SL; length of caudal peduncle, CPL, mean 0.22 (range 0.209 –0.231) of SL; depth of caudal peduncle, CPD, mean 0.326 (range 0.277 –0.365) of CPL, length of caudal peduncle; length of snout to centre of eye, LSc, mean 0.322 (range 0.292 –0.362) of HL; length of snout to posterior orbital rim of eye, LSo, mean 0.429 (range 0.4–0.484) of HL; head length, HL, mean 0.24 (range 0.225 –0.248) of SL; distance between the pair of nares of one side, Na, mean 20.03 (range 18.86–21.71) times in HL, head length; body depth, BD, mean 0.283 (range 0.24–0.312) of SL; dorsal fin ray number, nD, median 19 (range 18–21); anal fin ray number, nA, median 27 (range 26–28); number of scales around caudal peduncle, SPc, median 12 (range, 12–12). Remarks. Petrocephalus haullevillii is distinguished from other Petrocephalus species by one of the shortest values for head length, HL, in combination with dorsal fin ray number, nD, in the lowest range. This leaves only P. stuhlmanni congicus as an alternative that differs, however, categorically in possessing a rosette of electroreceptor organs above the eye (Augenrosette; Harder 1968), in contrast to haullevillii that possesses none (S. Lavoué, personal communication)

Published as part of Kramer, Bernd, Bills, Roger, Skelton, Paul & Wink, Michael, 2012, A critical revision of the churchill snoutfish, genus Petrocephalus Marcusen, 1854 (Actinopterygii: Teleostei: Mormyridae), from southern and eastern Africa, with the recognition of Petrocephalus tanensis, and the description of five new species, pp. 2179-2258 in Journal of Natural History 46 (35 - 36) on pages 2236-2237, DOI: 10.1080/00222933.2012.708452, http://zenodo.org/record/4590828