Petrocephalus boboto Lavoué & Sullivan 2014

Diagnosis: Petrocephalus boboto is distinguished from all other Petrocephalus species of Central Africa by the following combination of characteristics: three distinctive bilateral black spots on body, one at origin of the pectoral fin, one at origin of caudal fin and one on flank just below anterior part of dorsal fin; two distinct electroreceptive rosettes in head, the third rosette reduced in size to few knollenorgan pores; 23 branched rays in dorsal fin and 34 branched rays in anal fin; and triphasic EOD waveform of normal polarity (Ref. 96601).Description: Body ovoid, 2.7 times longer than high and laterally compressed (Ref. 96601). Head length 3.3 times in standard length; snout short and round, ratio head length and snout length 6.6 (Ref. 96601). Mouth small, ratio of head length and mouth width 4.4; subterminal, opening under anterior half of eye (Ref. 96601). Teeth small and bicuspid, 13 in single row in upper jaw, 24 in single row in lower jaw (Ref. 96601). Nostrils closely set, the distance between nostrils 0.4 mm, with the posterior one very close to eye, the distance between posterior nostril and eye 0.1 mm (Ref. 96601). Caudal peduncle narrow, ratio lenght/height 1.6 (Ref. 96601). Dorsal and anal fins originating in posterior half of body; predorsal distance slightly greater than pre-anal distance; dorsal fin with 23 branched rays; anal fin with 34 branched rays; pectoral fins with 9 rays; distance between pelvic and anal fin 10.1 mm; distance between pectoral fin and anal fin 16.4 mm (Ref. 96601). Scales cover body, except for head; lateral line visible and complete with 34 pored scales along its length; ten scales around caudal peduncle; ten scales between anterior base of anal fin and lateral line (Ref. 96601). Thick skin on head; knollenorgans visible, clustered into two distinct rosettes; knollenorgan pores in front of eye not highly condensed in the form of a discernable Augenrosette (Ref. 96601).Colouration: Body background colour uniformly gray/silver with metallic reflection on the flanks and head; light melanophores densely and evenly distributed on body, slightly larger on head; three distinct black marks on each side of the body, one at the base of the pectoral fins, one at the base of the caudal fin and one subdorsal, below the first anterior rays of the dorsal fin; all fins hyaline (Ref. 96601). Preserved colouration: background beige with dorsum slightly darker; numerous light melanophores visible all over body; thick skin on head and fins opaque; three distinct melanin marks on side of body distinctly visible (Ref. 96601).

fisheries:

Petrocephalus boboto is a species of electric fish in the genus Petrocephalus. It is so far only known from the holotype collected from Congo River at Yangambi, the Democratic Republic of the Congo. The specific name boboto is Lingala word for "peace".

Morphometric ratios and meristic data for holotype presented in Table 1. Standard length = 56.9 mm. Sex undetermined: specimen lacks anal fin “notch” present in mature males, but may be juvenile. Body ovoid, 2.7 times longer than high and laterally compressed. Head length 3.3 times in standard length. Snout short (HL/SNL = 6.6) and round. Mouth small (HL/MW = 4.4), subterminal, opening under anterior half of eye. Teeth small and bicuspid, 13 in single row in upper jaw, 24 in single row in lower jaw. Nostrils closely set (distance between nostrils = 0.4 mm) with the posterior one very close to eye (distance between posterior nostril and eye = 0.1 mm). Dorsal and anal fins originating in posterior half of body (SL/PDD = 1.6 and SL/PAD = 1.8). Pre-dorsal distance slightly greater than pre-anal distance (PDD/PAD = 1.1). Dorsal fin with 23 branched rays. Anal fin with 34 branched rays. Pectoral fins with 9 rays. Pelvic fin with 6 rays. Distance between pelvic fin and anal fin = 10.1 mm. Distance between pectoral fin and anal fin = 16.4 mm. Scales cover body, except for head. Lateral line visible and complete with 34 pored scales along its length. Ten scales around caudal peduncle. Ten scales between anterior base of anal fin and lateral line. Caudal peduncle narrow (CPL/CPD = 1.6). Thick skin on head. Knollenorgans visible, clustered into two distinct rosettes, Nackenrosette and Kehlrosettes as described in Harder (1968). Knollenorgan pores in front of eye not highly condensed in the form of a discernable Augenrosette. Principal morphometric ratios and meristic counts for the holotype (CUMV 96774) of Petrocephalus boboto sp. n. from Yangambi, the holotype (MRAC 15191) of Petrocephalus binotatus from Ikengo, the holotype (CUMV 88074) and the 17 paratypes (CUMV 88076, 88079, 88041, 87838, 88063, 87785, 88052, 88053, 92390, 87830, 88080, 88123, 88064, 88065, 88031 and 88032) of Petrocephalus arnegardi sp. n., all from Odzala-Kokua National Park, and two other specimens (BMNH 2013.8.29.34 and 2013.8.29.125) of Petrocephalus arnegardi sp. n. from Yangambi. Abbreviations: u = sex undetermined; m = sexually mature male; Min-Max = minimum-maximum; stdev = standard deviation. “*” indicates data from Pellegrin (1924). Petrocephalus boboto sp. n. Petrocephalus binotatus Petrocephalus arnegardi sp. n. Holotype (u) from Yangambi Holotype (m) from Ikengo Holotype (m) from Odzala Paratypes from Odzala Two non-types (u, m) from Yangambi Min–Max Mean (stdev) Standard length (mm) 56.9 83.2 72.6 62.8–90.1 72.1 48.9, 76.0 Head length (mm) 17.4 23.1 21.6 17.3–24.6 20.3 12.3, 20.2 Ratio of standard length (SL): SL/body height (H) 2.7 2.4 2.5 2.3–2.8 2.6 (0.2) 2.8, 2.6 SL/head length (HL) 3.3 3.6 3.4 3.4–3.9 3.6 (0.2) 4.0, 3.8 SL/pre-dorsal distance (PDD) 1.6 1.6 1.5 1.4–1.6 1.5 (0.0) 1.6, 1.6 SL/pre-anal distance (PAD) 1.8 1.7 1.6 1.6–1.7 1.7 (0.0) 1.8, 1.7 SL/dorsal fin length (DFL) 5.1 4.5 4.9 4.2–5.4 5.0 (0.3) 5.0, 4.9 SL/anal fin length (AFL) 3.0 2.8 3.1 2.8–3.3 3.0 (0.2) 3.2, 3.1 SL/caudal peduncle length (CPL) 6.3 7.0 6.4 5.7–7.5 6.7 (0.5) 5.8, 7.6 SL/mouth width (MW) 14.2 11.6 15.1 14.7–18.4 16.4 (1.1) 18.0, 15.8 Ratio of head length (HL): HL/snout length (SNL) 6.6 5.5 8.3 6.5–9.3 7.5 (0.8) 5.1, 5.8 HL/mouth width (MW) 4.4 3.2 4.5 4.1–5.0 4.6 (0.2) 4.5, 4.2 HL/eye diameter (ED) 4.4 3.6 4.1 3.5–4.4 4.0 (0.3) 4.2, 4.7 HL/interorbital width (IOW) 3.7 2.3 3.3 2.6–3.9 3.2 (0.3) 2.9, 2.6 HL/head width (HW) 2.4 1.9 2.2 1.8–2.2 2.1 (0.1) 1.9, 1.9 HL/mouth position (MP) 4.4 3.9 5.5 4.2–5.6 4.8 (0.4) 4.4, 4.4 Ratio of caudal peduncle length (CPL): CPL/caudal peduncle depth (CPD) 1.6 2.3 2.2 1.8–2.5 2.2 (0.2) 2.6, 2.0 Meristic counts: Dorsal fin branched rays (DR) 23 24 20 20–22 21 (1) 20, 22 Anal fin branched rays (AR) 34 33 32 31–34 32 (1) 30, 32 Number of lateral line scales (SLL) 34 37 37 34–38 36 (1) 36, 36 Number of scale rows between anterior base of anal fin and lateral line (SDL) 10 11 12 10–13 11 (1) 10, 10 Number of teeth in upper jaw (TUJ) 13 15* 8 9–16 10 (1) 9, 11 Number of teeth in lower jaw (TLJ) 24 24* 20 20–24 21 (1) 25, 21 Electric organ discharge (Fig. 2A). Short triphasic EOD waveform, first phase head-positive. Relative height of peak 1 = 0.241, relative height of peak 2 = -0.759, relative height of peak 3 = 0.053, duration of peak 1 = 0.137 msec, duration of peak 2 = 0.041 msec, duration of peak 3 = 0.079 msec, total EOD duration = 0.257 msec. Based on characteristics of the EOD, the electrocytes are assumed to have non-penetrating stalks and to be innervated posteriorly (Sullivan et al. 2000). Live coloration (Fig. 3). Body background color uniformly gray/silver with metallic reflection on the flanks and head. Light melanophores densely and evenly distributed on body, slightly larger on head. Three distinct black marks on each side of the body, one at the base of the pectoral fins, one at the base of the caudal fin and one subdorsal, below the first anterior rays of the dorsal fin. All fins hyaline. Preserved coloration (Fig. 3). Background beige with dorsum slightly darker. Numerous light melanophores visible all over body. Thick skin on head and fins opaque. Three distinct melanin marks on side of body distinctly visible.

(Fig. 1). Holotype (and only specimen known) of Petrocephalus boboto sp. n. collected from the main channel of the Congo River, at Yangambi, Orientale Province, Democratic Republic of Congo.