Petrocephalus petersi, Kramer & Bills & Skelton & Wink, 2012

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, Journal of Natural History 46 (35 - 36), pp. 2179-2258 : 2244-2245

Petrocephalus petersi sp. nov.

( Figure 2, no. 21)

Type specimens. Holotype: SAIAB 060846 (specimen R1 ), Mozambique, stream near campsite 1, edge of wet Zambezi River System , Zambezi River . Paratypes: SAIAB 186055 (10 specimens) .

Type locality. Mozambique, stream near campsite 1, edge of wet Zambezi River System , Zambezi River, 18 ◦ 33 ′ 54 ′′ S, 35 ◦ 39 ′ 46 ′′ E .

Diagnosis. 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 posterior 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) .

Description. Body round-oval shape ( Figure 2, no. 21). 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 ( Table 1). 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.

Ecology. Only collected at one site near camp 1 where local fisherwomen had poisoned a small stream. One of two mormyrids present there and it accounted for less than 4% of the population. The habitat was a medium-sized stream, sand substrate with lots of leaf litter and marginal grass. Petrocephalus petersi sp. nov. is regarded as rare, and prefers freshwater (<1% salinity). Online Figure 11 .

Distribution. Presently only known from the Zambezi delta region.

Etymology. The species name petersi is given in honour of the German herpetologist Wilhelm C. H. Peters who, until recently, during his Naturwissenschaftliche Reise nach Mossambique 1842–1848, had carried out the only major fish survey of the lower Zambezi region, and discovered many of the endemics and other more widespread species ( Peters 1868; Bills 2000).

Remarks. In comparison, P. petersi sp. nov. is characterized by a very long PAL, long PDL, long LSc and LSo, quite high BD, and a usually high SPc.

Figures

Figure 11. Oscilloscope traces of Electric Organ Discharges (EODs) of members of southern and eastern African Petrocephalus species. (A) P. longicapitis sp. nov. (B) P. tanensis, (C) P. wesselsi, (D) P. okavangensis sp. nov. Ordinate, voltage, with head-positivity upwards from baseline: shown in (A). Abscissa, time (see time bar); same scale everywhere. EOD amplitude scaled to first head-positive phase P1 = 1; P2, second head-positive phase; N, head-negative phase. EODs superimposed with temporal offset to better show differences among individuals: differences between the sexes statistically significant in (A) and (B).