Petrocephalus longianalis, 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 : 2237-2238

Petrocephalus longianalis sp. nov.

( Figure 2, no. 12)

Type specimens. Holotype: SAIAB 76758 (specimen R9 ) from Zambia Province: Luapula System: Luongo River : Lufubu River . Paratypes: SAIAB 186060 (48 specimens) .

Type locality. Zambia, Zambia Province, Luapula System, Luongo River , Lufubu River , Lufubu River Falls below bridge at Chipili on Mensa-Mununga road 10.7297 ◦ S, 29.0936 ◦ E .

Diagnosis. Number of anal fin rays, nA, median 33 (range 30–35); anal fin length, LA, mean 0.261 (range 0.244 –0.278) of SL; preanal length, PAL, mean 0.569 (range 0.543–0.59) of SL; depth of caudal peduncle, CPD, mean 0.298 (range 0.269 –0.331) of CPL, length of caudal peduncle; body depth, BD, mean 0.267 (range 0.225 –0.293) of SL; number of dorsal fin rays, nD, median 24 (range 22–26); number of scales in lateral line row, SLS, median 40 (range 39–42); distance between anterior base of pectoral fin to anterior base of pelvic fin, PPf, mean 0.152 (range 0.128 –0.169) of SL.

Description. Body long-oval shape ( Figure 2, no. 12). 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 22 (n = 8), 23 (n = 20), 24 (n = 18), 25 (n = 3), (e) dark spot below fin origin (lacking in samples from Luapula River bridge, SAIAB 76582). 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 30 (n = 2), 31 (n = 6), 32 (n = 16), 33 (n = 17), 34 (n = 6), 35 (n = 2). Forked tail fin with rounded lobes. Scales cycloid with reticulate striae, scales extending anteriorly to operculum and pectoral fins (beyond pelvics). Scales in lateral series, 39 (n = 9), 40 (n = 17), 41 (n = 21), 42 (n = 2). Scales on caudal peduncle circumference, 11 (n = 2), 12 (n = 47). Caudal peduncle slender, subcylindrical entire length, usually 19.3% (18.4–19.9%) 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. Body brown, back only slightly darker, breast and belly fair, fins rather unpigmented and transparent, anal and dorsal fin bases emphasized as dark

lines. Well-circumscribed dark spot below dorsal fin origin (except for specimens from Luapula River bridge, SAIAB 76582).

Ecology. The Lufubu River just above a 3–4 m falls is a braided rocky channel with dense riparian forest. Water flow was rapid in section but there were also deeper pools with large rocks providing slacker flow areas. The substrate was rocky but with considerable amounts of leaf litter. In some sections there were mats of aquatic water ferns and mosses and filamentous algae. Fishes were collected with rotenone. Altitude, approximately 1200 m. Online Figure 6 .

Remarks. A median of nA = 33 is highest and distinctive among the Petrocephalus species of the present study. Except for samples from Luapula River bridge (SAIAB 76582), all other samples referable to P. longianalis sp. nov. with dark spot below dorsal fin origin, usually round, small and distinct.

Figures

Figure 6. As Figure 1, but area of Petrocephalus okavangensis sp. nov. and location from where samples were taken shown at better resolution. (9) Nguma (Guma) Lagoon. (31) Boro River. (32) Gadikwe Lagoon. (33) Xakanixa River. (34) Xakanixa Channel. (35) Popa Rapids. (8) unique specimen from Kwando River.