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The recent description of a distinctive new pimelodid catfish, Pimelabditus moli Parisi {&} Lundberg, 2009, from the Maroni River basin of Suriname and French Guiana, added an unresolved taxon to the family. Here we include P. moli in ongoing molecular and morphological phylogenetic studies of the Pimelodidae. We sequenced > 7.5 KB of aligned bases from the nuclear rag1 and rag2 genes and the mitochondrial mt-rnr1, mt-rnr2 and mt-cyb genes. Results provide strong support for the placement of P. moli as the sister taxon to Pimelodus ornatus Kner, 1858. We also describe a structurally complex pterotic-epioccipital fossa shared by P. moli and P. ornatus that provides an unambiguous synapomorphy indicating their close relationship. Furthermore, the molecular and morphological data recover the P. moli -P. ornatus Clade as the sister group to the Calophysus-Pimelodus Clade. Pimelabditus moli is a rare species, known from just five specimens. Notes on the provenance, capture and habitat of P. moli are provided.

Transnational organized crime is a pressing global security issue. Mexico is currently embroiled in a protracted drug war. Mexican drug cartels and allied gangs (actually poly-crime organizations) are currently challenging states and sub-state polities (in Mexico, Guatemala, El Salvador and beyond) to capitalize on lucrative illicit global economic markets. As a consequence of the exploitation of these global economic flows, the cartels are waging war on each other and state institutions to gain control of the illicit economy. Essentially, they are waging a 'criminal insurgency' against the current configuration of states. As such, they are becoming political, as well as economic actors. This presentation examines the dynamics of this controversial proposition. The control of territorial space -- ranging from 'failed communities' to 'failed regions' -- will be examined. The presentation will examine the exploitation of weak governance and areas (known as 'lawless zones,' 'ungoverned spaces,' 'other governed spaces,' or 'zones of impunity') where state challengers have created parallel or dual sovereignty, or 'criminal enclaves' in a neo-feudal political arrangement. The use of instrumental violence, corruption, information operations (including attacks on journalists), street taxation, and provision of social goods in a utilitarian fashion will be discussed. Finally, the dynamics of the transition of cartels and gangs into 'accidental guerrillas' and 'social bandits' will be explored through the lens of 'third generation gang' theory and 'power-counter power' relationships. This presentation will serve as a starting point for assessing the threat to security from transnational organized crime through lessons from the Mexican cartels.

Petrocephalus sauvagii (Boulenger, 1887) Mormyrus (Petrocephalus) sauvagii Boulenger (1887): 149. Mormyrus sauvagii Steindachner (1895): 69. Petrocephalus sauvagii Boulenger (1898): 19 - Taverne (1972): 162 - Gosse (1984): 113. [Odzala field identification: Petrocephalus sp. 8, OTU 8] Images. Fig. 10 A, photo of a live specimen from Odzala, Fig. 10 B, photo of a preserved specimen from Odzala and Fig. 14, drawing of the holotype (BMNH 1887.1.13.3) from Boulenger (1909 ���1916). Photo of the holotype in Harder (2000). Type material. Holotype, BMNH 1887.1. 13.3 "in the creeks of the Lower Congo and the tributary streams, without more precision, unknown coll." Other specimens. We examined six specimens from Odzala and four additional specimens from the Lower Niger River (specimen list provided in the section "additional material examined"). Diagnosis. We prepared the following diagnosis using all the specimens of P. sauvagii that we examined, regardless their geographic origins. Petrocephalus sauvagii is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Very wide mouth (HL/MW ��� 3.7, range = 2.7���3.7) associated with a characteristic head shape when viewed from below. Twenty-four to 30 teeth in the upper jaw and 30���34 in the lower jaw. Anal fin with at least 32 branched rays (range = 32���38). Dorsal fin with at least 25 branched rays (range = 25���30). Mouth sub-terminal; ratio between the head length and the mouth position as large as 7.4 (range = 5.5���7.4). Pigmentation pattern with two melanin markings, sometimes of weak intensity or even scarcely visible: (1) an irregularly round black mark below the anterior base (first to fourth rays) of the dorsal fin; and (2) an ovoid blackish mark, often irregularly shaped, at the base of the caudal fin, extending onto the upper and lower fleshy lobes of the fin. EOD of normal polarity, with two main phases followed by a third, smaller phase. Description. Table 8 provides morphometric ratios and meristic data for the holotype, six non-type specimens from Odzala and four non-type specimens from the Lower Niger River. However, the following description corresponds only to the six Odzala specimens we examined, except where separate reference is made to the holotype. Petrocephalus sauvagii is the largest Petrocephalus species occurring in the Odzala assemblage (maximum SL observed in Odzala = 189.0 mm, holotype = 146.7 mm). Body ovoid, longer than high (2.7 ��� SL /H ��� 3.4, average = 3.0, holotype = 2.9) and laterally compressed. Head length between 3.5 and 3.7 times in standard length (average = 3.6, holotype = 3.7). Eye small (4.1 ��� HL/ED ��� 4.5, average = 4.3, holotype = 4.6). Snout very short (6.3 ��� HL/SNL ��� 9.9, average = 8.0, holotype = 6.7) and round. Mouth distinctively large (3.1 ��� HL/MW ��� 3.7, average = 3.3, holotype = 3.1), sub-terminal (5.5 ��� HL/MP ��� 7.4, average = 6.6, holotype = 4.9), opening just under the anterior half of the eye. Dentition consisting of many small bicuspid teeth, 24���30 (median = 26, holotype = 26) in a single row in the upper jaw, 30���34 (median = 32, holotype = 30) in a single row in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.5 ��� SL / PDD ��� 1.6 and 1.5 ��� SL /PAD ��� 1.7). Pre-dorsal distance equal to, or slightly greater than, preanal distance (1.0 ��� PDD /PAD ��� 1.1). Anal fin with 33���38 branched rays (median = 35, holotype = 34). Dorsal fin with 26���30 branched rays (median = 28, holotype = 27). Scales cover the body, except for the head. Lateral line visible and complete with 38���41 (median = 39, holotype = 36) pored scales along its length. Twelve to 16 scales (median 14, holotype = 14) between the anterior base of the anal fin and the lateral line. Caudal peduncle relatively thin (2.3 ��� CPL/CPD ��� 3.1, average = 2.6, holotype = 2.7). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation, with Knollenorgan electroreceptors organized into three relatively small rosettes. Holotype Specimens Specimens from (m) from Odzala Lower Niger (n= 6) (n= 4) Min���Max Mean Std���Dev Min���Max Mean Std���Dev Live coloration (Fig. 10 A). Body uniformly white-silver with metallic iridescence. Two characteristic melanin markings are present, sometimes with very weak intensity in large individuals: (1) an irregular round mark below the anterior base (first to fourth rays) of the dorsal fin; (2) an ovoid blackish mark, often irregular in shape, centered at the base of the caudal fin and extending onto the upper and lower fleshy lobes of this fin. The fins themselves (caudal fins and others) are translucent. Distribution (Fig. 1). Petrocephalus sauvagii is the only species of Petrocephalus known to occur in both the Congo and Niger basins. There is no record of this species occurring in the Lower Guinea province. The holotype was collected from " the creeks of the Lower Congo and the tributary streams " without more precision being given on the exact locality (Boulenger, 1887). In Odzala, we collected P. sauvagii at several localities along the main course of the L��koli River and, exclusively at night, in some small tributary creeks flowing through savannah. Electric organ discharge (Fig. 10 C). EOD recordings are only available for three individuals. Thus, generalizations about the EOD features of this species must be made with caution. EOD waveforms of all three individuals are of somewhat short duration for the genus (range = 0.232 ��� 0.273 msec), but they are, nevertheless, very similar to EODs of several other Petrocephalus species. Statistics for waveform landmarks and other EOD measurements for P. sauvagii are provided by Lavou�� et al. (2008), who demonstrated histologically that the electrocytes of this species are type NPp. Remarks. We noticed some morphological differences between allopatric specimens of P. sauvagii from the Niger and Congo basins. Specimens from the Niger basin possess fewer anal fin rays (32���33 versus 33��� 38), a longer snout (HL/SNL = 5.5���6.8 versus 6.3���9.9) and a greater interorbital width (HL/IOW = 2.6���2.7 versus 3.5���4.2) than Odzala specimens., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 29-32, DOI: 10.5281/zenodo.197589, {"references":["Boulenger, G. A. (1887) On new fishes from the lower Congo. Annals and Magazine of Natural History, 19, 148 - 149.","Steindachner, F. (1895) Die Fische Liberia's. Notes from the Leyden Museum, 16, 1 - 96.","Boulenger, G. A. (1898) A revision of the genera and species of fishes of the family Mormyridae. Proceedings of the Zoological Society of London, 1898, 775 - 821.","Taverne, L. (1972) Osteologie des genres Mormyrus Linne, Mormyrops Muller, Hyperopisus Gill, Myomyrus Boulenger, Stomatorhinus Boulenger et Gymnarchus Cuvier. Considerations generales sur la systematique des Poissons de l'ordre des Mormyriformes. Annales du Musee Royal de l'Afrique Centrale, Sciences Zoologiques, 200, 1 - 194.","Boulenger, G. A. (1909 - 1916) Catalogue of the Freshwater Fishes of Africa in the British Museum (Natural History). Wheldon and Wesley, London, 4 volumes.","Harder, W. (2000) Mormyridae and other Osteoglossomorpha. World Biodiversity database, CD - ROM series, ETI BioInformatics, Amsterdam.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus grandoculis Boulenger, 1920 Petrocephalus grandoculis Boulenger (1920): 10. [Odzala field identification: Petrocephalus sp. 10, OTU 10] Images. Fig. 12 A, photo of a live specimen from Odzala, Fig. 12 B, photo of a preserved specimen from Odzala and Fig. 14, drawing of one syntype from Boulenger (1920), p. 10. Photo of two syntypes in Harder (2000). Type material. Syntypes, BMNH 1919.9.10.16��� 17 [examined] and MRAC 7158, 7167 [not examined]. Leopoldville (Kinshasa), Zaire (Democratic Republic of the Congo)[estimated 4.25 �� S, 15.33 �� E]. Other specimens. We also examined two specimens from Odzala National Park (specimen list provided in the section ���additional material examined���). Diagnosis. The following diagnosis is based on all examined specimens of P. grandoculis, regardless their geographic origins. Petrocephalus grandoculis is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Very small mouth (5.2 ��� HL/MW ��� 6.1). Eight to 11 teeth in the lower jaw. Upper jaw with 18���22 teeth. Eye large (2.8 ��� HL/ED ��� 3.2). Snout short (6.5 ��� HL/SNL ��� 10.7). Dorsal fin with 24���26 branched rays. Anal fin with 30���33 branched rays. Pigmentation pattern consists of two melanin markings (black patches): (1) a distinct, although generally weak, round black mark on each side of the body below the anterior base of the dorsal fin (first to fifth rays); and (2) a crescentlike mark at the base of the caudal fin on each side, not extending onto the rayed portions of the upper and lower caudal fin lobes. EOD of normal polarity. Min���Max Min���Max Meristic counts: Number of scale rows between the anterior base of 15 ��� 15 13���15 11 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 10���11 8 ��� 8 12 Number of teeth in the lower jaw (TLJ) 19���20 18���22 14 Description. Table 10 provides morphometric ratios and meristic data for the two Kinshasa syntypes and, separately, for the two non-type specimens from Odzala National Park. The following description applies to the two Odzala specimens, with separate reference to the two syntypes. Petrocephalus grandoculis is a medium-sized species within the genus Petrocephalus (maximum SL observed = 97.8 mm). Body ovoid, longer than high (2.5 ��� SL /H ��� 2.7, syntypes = 3.0��� 3.1) and laterally compressed. Head length 3.8���4.2 times in standard length (syntypes = 3.9���4.1). Eye quite large (2.8 ��� HL/ED ��� 3.1, syntypes = 3.1���3.2). Snout short (6.5 ��� HL/SNL ��� 10.7, syntypes = 6.5���6.7) and round. Mouth very small (5.2 ��� HL/MW ��� 5.9, syntypes = 5.7���6.1), sub-terminal, opening under the anterior half of the eye. Teeth small and bicuspid, only eight (syntypes = 10 or 11) in a single row in the upper jaw, 18���22 (syntypes = 19 or 20) in a single row in the lower jaw. Dorsal and anal fins originate in the posterior half of the body [SL / PDD = 1.6 and SL /PAD = 1.7 (syntypes = 1.7���1.8), respectively]. Pre-dorsal distance slightly greater than pre-anal distance (1.0 ��� PDD / PAD ��� 1.1). Dorsal fin with 25���26 branched rays (syntypes = 24���26). Anal fin with 32 or 33 branched rays (syntypes = 30 or 31). Scales cover the body, except for the head. Lateral line visible and complete with 37���39 (syntypes = 38) pored scales along its length. Caudal peduncle relatively thin (2.2 ��� CPL/CPD ��� 3.0, syntypes = 3.0). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation. The numerous Knollenorgan electroreceptors on the head are clearly organized into two visible rosettes (Augenrosette and Nackenrosette). In our examination of specimens, we were uncertain about the definitive presence of the third rosette, the Kehlrosette, as this structure did not appear to us to be as distinct as it is in other species (e.g., P. binotatus). However, more definitive recent analysis using toluidine blue staining of the skin now suggests that the Kehlrosette is present, but smaller and harder to discern than in other Petrocephalus (M. Hollmann and B. A. Carlson, unpub. obs.). Live coloration (Fig. 12 A). Body mostly white-silver. Dorsum slightly darker than the rest of the body. Pigmentation pattern consists of two melanin markings: (1) a distinct, but weak, round black mark below the anterior base of the dorsal fin (first to fifth rays); and (2) a crescent-shaped mark at the base of the caudal fin, which does not extend onto the rayed portions of the upper and lower caudal fin lobes. No black mark is present at the base of pectoral fins. The fins themselves are translucent. Distribution (Fig. 1). Endemic to the Congo basin. The type locality is situated on the Lower Congo River at Kinshasa. In Odzala, we collected only two specimens of P. grandoculis from the main channel of the L��koli River. Electric organ discharge (Fig. 12 C). EODs have only been recorded from one individual of P. grandoculis, which was collected in Odzala National Park. The EOD duration for this individual (0.380 msec, based on 1.5 % deviations from baseline) and the general appearance of the waveform are typical for Petrocephalus. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008). Electrocyte anatomy is unknown, although it is expected to be type "NPp" as deduced from the EOD waveform., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 35-38, DOI: 10.5281/zenodo.197589, {"references":["Boulenger, G. A. (1920) Poissons recueillis au Congo Belge par l'expedition du Dr C. Christy. Materiaux pour la faune du Congo. Annales du Musee du Congo, Zoologie, 2, 1 - 38.","Harder, W. (2000) Mormyridae and other Osteoglossomorpha. World Biodiversity database, CD - ROM series, ETI BioInformatics, Amsterdam.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus microphthalmus Pellegrin, 1908 Petrocephalus microphthalmus Pellegrin (1908): 185. [Odzala field identification: Petrocephalus sp. 5, OTU 5] Images. Fig. 7 A, photo of a live specimen from Odzala, Fig. 7 B, photo of a preserved specimen from Odzala and Fig. 14, drawing from Poll (1967) of a specimen collected in Angola. Photo of the holotype (MNHN 1908 ��� 211) in Lavou�� et al. (2004). Type material. Holotype, MNHN 1908 ��� 211, male, 73.7 mm SL. Gabon, Ogoou�� basin at Ngomo (Lower Ogoou��) [estimated 0.82 S, 9.95 E], E. Haug coll. Other specimens. We examined 14 other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). A list of additional specimens examined from Lower Guinea is given in Lavou�� et al. (2004). Diagnosis. We prepared the following diagnosis using all the specimens of P. microphthalmus that we examined, regardless their geographic origins. Petrocephalus microphthalmus is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Short dorsal fin with only 18 or fewer branched rays (range 15���18). Long anal fin with 23���27 branched rays. Eye small (4.0 ��� HL/ ED, range = 4.1���4.8). Mouth moderately wide (3.5 ��� HL/MW ��� 4.9). Only 9���11 teeth in the upper jaw, 14���20 teeth in the lower jaw. Absence of black pigment patches, except for a characteristic black blotch on the anterior dorsal fin rays near the origin of this fin. Body silvery/purplish, iridescent. Electroreceptors on the head are not clustered into "rosettes" but, instead, appear as isolated receptor pores. EOD of normal polarity with two main phases and, in Odzala, a third minute phase of very low amplitude. Description. Morphometric ratios and meristic data for the holotype (from Gabon) and the non-type specimens (from Odzala and Lower Guinea) are presented in Table 5. However, the following description is based only on the Odzala specimens we examined, except where we make separate reference to the holotype. With a maximum observed standard length of 59.1 mm in Odzala National Park, P. microphthalmus is the smallest species in the diverse Odzala assemblage of Petrocephalus. Body ovoid, longer than high (2.6 ��� SL / H ��� 2.8, holotype = 2.7) and laterally compressed. Head length between 3.8 and 4.0 times in standard length (average = 3.9, holotype = 4.0). Snout short (5.2 ��� HL/SNL ��� 6.4, average = 5.8, holotype = 4.6) and round. Mouth small (3.6 ��� HL/MW ��� 4.2, average = 3.9, holotype = 3.8), opening under the eye. Teeth small and bicuspid, 9���11 (holotype = 10) in a single row in the upper jaw, 14���16 (holotype = 20) in a single row in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (SL / PDD = 1.5 and SL /PAD = 1.7). Pre-dorsal distance slightly greater than pre-anal distance (PDD /PAD ��� 1.1). Dorsal fin with 16���18 branched rays (holotype = 16). Anal fin with 26���27 branched rays (holotype = 25). Scales cover the entire body, except for the head. Lateral line visible and complete with 34 to 35 pored scales along its length (holotype = 36). Eight to 10 scales between the anterior base of the anal fin and the lateral line. Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation, containing numerous Knollenorgan electroreceptors that do not form "rosettes" in their typical positions. Instead, Knollenorgans appear as isolated receptor pores in the skin covering the head, the character state observed in the Mormyrinae. Holotype Specimens Specimens from (m)* from Odzala Gabon (Ogoou�� (n= 3) River) (n= 36)* Live coloration (Fig. 7 A). Body generally blue-gray, with the dorsum darker than the abdomen. Numerous chromatophores occur below the skin surface. This species can appear metallic blue to violet depending on the angle and intensity of illumination. The color is especially intense on the operculum. The fins are translucent except for the first dorsal fin rays, which are black near their insertion (Lavou�� et al., 2004). Distribution (Fig. 1). Present in Congo and Lower Guinea provinces. Holotype from Gabon. Abundant in Odzala, where we collected P. microphthalmus in small tributary creeks flowing through forest. Elsewhere in the Congo basin it is present in the Lower Congo River in the vicinity of Brazzaville. In the Lower Guinea province this species is widespread throughout the entire Ogoou�� and Ntem basins in Gabon, including streams and lakes associated with main river channels (e.g., Lac Zil��). It can also be found along the coastal region from the Sanaga River (Cameroon) in the north to the more southern Niari-Kouilou River (Republic of the Congo). Electric organ discharge (Fig. 7 C). Petrocephalus microphthalmus produces EODs of short duration, which are typical of the entire genus. No sex differences have yet been reported in any population. Similar EOD durations have been observed in the Odzala population of P. microphthalmus [range = 0.252 ��� 0.511 msec; Lavou�� et al. (2008)] and among conspecifics from Gabon [range = 0.380 ��� 0.561 msec; Lavou�� et al. (2004)]. A relatively long, slow rise characterizes the initial part of the first head-positive phase in EODs recorded from the Odzala population, often resulting in a shoulder early during the waveform���s head-positive rise to P 1, the first main peak (Lavou�� et al., 2008). The early head-positive rise and shoulder are very low in amplitude, however, such that they may only be apparent at high amplifier gain. These subtle waveform features appear to be uncommon in EODs of other Petrocephalus species. A similar slow rise (and shoulder) preceding P 1 has been recorded among a small number of P. microphthalmus individuals from Gabon, but it seems to be much less common than in Odzala. Additional statistics for waveform landmarks and other EOD measurements for the Odzala population are provided by Lavou�� et al. (2008). Based on histological examination, electrocytes are known to be type NPp (Lavou�� et al., 2008; Sullivan et al., 2000). Remarks. Petrocephalus microphthalmus closely resembles Petrocephalus schoutedeni Poll, 1954 and Petrocephalus catostoma haullevillii Boulenger, 1912. Petrocephalus microphthalmus is distinguished from P. schoutedeni mainly by the shape of the caudal peduncle: in the Odzala specimens its length is only 2.7 times (holotype = 2.9 times) its depth, versus 3.4���3.7 times in P. schoutedeni. We did not find any unambiguous morphological differences with which to distinguish P. microphthalmus and P. catostoma haullevillii., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 19-22, DOI: 10.5281/zenodo.197589, {"references":["Pellegrin, J. (1908) Sur une seconde collection de poissons recueillis par M. E. Haug a Ngomo. Bulletin de la Societe Philomatique de Paris, 11, 184 - 190.","Poll, M. (1967) Contribution a la Faune Ichthyologique de l'Angola. Companhia de Diamantes de Angola (Diamang), Lisboa, pp 381.","Lavoue, S., Hopkins, C. D. & Kamdem Toham, A. (2004) The Petrocephalus (Pisces, Osteoglossomorpha, Mormyridae) of Gabon, Central Africa, with the description of a new species. Zoosystema, 26, 511 - 535.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339.","Sullivan, J. P., Lavoue, S. & Hopkins, C. D. (2000) Molecular systematics of the African electric fishes (Mormyroidea: Teleostei) and a model for the evolution of their electric organs. Journal of Experimental Biology, 203, 665 - 683.","Boulenger, G. A. (1912) Poissons recueillis dans la region du Bas-Congo par le Dr. W. J. Ansorge. Annales du Musee du Congo, Zoologie, 2, 1 - 25."]}

Petrocephalus zakoni n. sp. [Odzala field identification and in Lavoué et al. (2008): Petrocephalus sp. 2, OTU 2] Images. Fig. 4 A, photo of a live specimen from Odzala and Fig. 4 B, photo of the preserved holotype (CU 88101). Type material. Holotype, CU 88101 (morpho, EOD), male, 86.0 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park, (0.62 ° N, 14.95 ° E). J.P. Friel, S. Lavoué & J.P. Sullivan coll., 20 August 2002. Paratypes. CU 88036 (morpho, EOD), sex undet., 81.4 mm SL; CU 88042 (morpho, EOD), male, 78.6 mm SL; CU 88037 (morpho, EOD), sex undet., 79.6 mm SL; CU 88077 (morpho), male, 84.8 mm SL. Republic of the Congo, Pandaka River (Congo basin), Odzala National Park, (0.62 ° N, 14.92 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. CU 88104 (morpho, EOD), sex undet., 83.5 mm SL; AMNH 251426 (ex CU 88100) (morpho, EOD), male, 73.7 mm SL; AMNH 251427 (ex CU 88103) (morpho, EOD), sex undet., 77.2 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park (0.62 ° N, 14.95 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. CU 88093 (morpho, EOD), male, 67.4 mm SL; AMNH 251424 (ex CU 88088) (morpho, EOD), sex undet., 75.8 mm SL; AMNH 251425 (ex CU 88090) (morpho, EOD), male, 76.0 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park (0.62 ° N, 14.92 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. Other specimens. We examined 34 other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus zakoni n. sp. is distinguished from all other Petrocephalus species in Central Africa (Lower Guinea and Congo provinces) by the following combination of characteristics. Dorsal fin with 23 or 24 branched rays. Anal fin with 27 or 28 branched rays. Eye large (HL/ED ≤ 3.3, range = 3.1–3.3). Mouth small (4.4 ≤ HL/MW, range = 4.4 –5.0). Ten teeth or fewer (range = 6–10) in the upper jaw. Twentytwo teeth or fewer (range = 18–22) in the lower jaw. Unique pigmentation pattern consisting of three well defined black patches (Fig. 4 A): (1) an intense dark mark on each side of the body close to the anterior base of the dorsal fin, often extending onto the first dorsal rays, forming a characteristic saddle across the dorsum; (2) a mark on each side of the body at the base of the pectoral fin; (3) a crescent-shaped mark on each side of the body centered at the base of the caudal fin, extending onto the upper and lower parts of the caudal fin. EOD of normal polarity (i.e., first major phase head-positive). Description. Morphometric ratios and meristic data are given in Table 2 for the holotype and paratypes separately. Petrocephalus zakoni n. sp. is a small sized species within the genus (maximum SL in the type series = 86.0 mm, maximum SL observed in all specimens = 90 mm). Body ovoid, longer than high (2.5 ≤ SL / H ≤ 2.8, paratype average = 2.6, holotype = 2.8) and laterally compressed. Head length between 3.4 and 3.7 times in standard length (paratype average = 3.6, holotype = 3.6). Eye large compared to many Petrocephalus species (3.1 ≤ HL/ED ≤ 3.3, paratype average = 3.2, holotype = 3.2). Snout short (6.1 ≤ HL/SNL ≤ 8.5, paratype average = 7.2, holotype = 6.2) and round. Mouth small (4.4 ≤ HL/MW ≤ 5.0, paratype average = 4.7, holotype = 4.5) and sub-terminal, opening under the posterior half of the eye. Teeth small and bicuspid, 6–10 (paratype median = 8, holotype = 9) in a single row in the upper jaw, 18–22 (paratype median = 19, holotype = 20) in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ≤ SL / PDD ≤ 1.7, paratype average and holotype = 1.6; 1.6 ≤ SL /PAD ≤ 1.7, paratype average and holotype = 1.6). Pre-dorsal distance roughly equal to the pre-anal distance. Dorsal fin with 23 or 24 branched rays (median = 23, holotype = 24). Anal fin with 27 or 28 branched rays (median = 27, holotype = 28). Scales cover the body, except for the head. Lateral line visible and complete with 36–38 pored scales along its length (paratype average = 37, holotype = 38). Twelve to 14 scales (paratype average = 13, holotype = 14) between the anterior base of the anal fin and the lateral line. Caudal peduncle thin (1.9 ≤ CPL/CPD ≤ 2.3, paratype average = 2.1, holotype = 2.2). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation. Knollenorgans on the head are not clustered into "rosettes" but, instead, appear as isolated receptor pores, the character state observed in the Mormyrinae. Live coloration (Fig. 4 A). Body uniformly white-silver, with the presence of three characteristic pigmentation marks: (1) a very distinctive black mark just below the anterior base of the dorsal fin on each side, often extending onto the first dorsal rays and making contact over the dorsum with the contralateral mark; (2) a blackish mark, sometimes weak but always visible, at the base of the pectoral fins; (3) a crescentshaped black mark centered at the base of the caudal fin on each side, extending onto the upper and lower parts of the caudal fin. Fins otherwise translucent. Distribution (Fig. 1). Apparently endemic to the Congo basin. Abundant in Odzala. We collected P. zakoni n. sp. at several localities along the main channel of the Lékoli River at night. Elsewhere in the Congo basin, we have identified specimens of P. z a k o n i n. sp. from the Lower Congo (Pool Malebo) and from the Sangha River basin (unpublished observations). Electric organ discharge (Fig. 4 C). EOD waveforms produced by P. zakoni n. sp. are of relatively short duration among Petrocephalus (range = 0.164–0.281 msec), but they are, nevertheless, very similar in waveform to the EODs of several other Petrocephalus species. EOD sex differences are not apparent in the Odzala population. Statistics for waveform landmarks and other EOD measurements are provided by Lavoué et al. (2008). Electrocytes are assumed to be of type NPp based on characteristics of the EOD, although electrocyte anatomy has not yet been confirmed histologically. Remarks. Given our identification of specimens from the Lower Congo River and the Dzangha-Sangha Reserve (Sangha River), Petrocephalus zakoni n. sp. is likely a common species in the Congo basin. This species has been previously misidentified as Petrocephalus christyi Boulenger, 1920 because its body proportions are similar to those of P. christyi. In addition, both species exhibit an intense sub-dorsal melanin marking on the flank. Nevertheless, these species can be distinguished by the presence of a black spot at the base of the pectoral fins in P. zakoni n. sp. (absent in P. christyi), the shape of the sub-dorsal marking (ovoid to saddle-shaped versus rounded in P. christyi), the waveshape of the EOD (with two main phases and a weak third phase in P. zakoni versus four phases in P. christyi) and presence/absence of Knollenorgan rosettes on the head (absent in P. zakoni versus present in P. christyi). Holotype (m) Paratypes (n= 10) Min–Max Mean Std–Dev Min–Max Median Meristic counts: Number of scale rows between the anterior base of 14 12–14 13 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 9 6–10 8 Number of teeth in the lower jaw (TLJ) 20 18–22 19 Etymology. Named in honor of Harold H. Zakon. In addition to Professor Zakon’s many contributions to neuroethology, we recognize the significance of his recent work (Zakon et al., 2006), which inspires a new area of research on genes that underlie electrolocation and electrical communication in gymnotiform and mormyroid fishes.

Petrocephalus pulsivertens n. sp. [Odzala field identification and in Lavoué et al (2008): Petrocephalus sp. 9, OTU 9] Images. Fig. 11 A, photo of a live specimen from Odzala and Fig. 11 B, photo of the preserved holotype (CU 88085). Type material. Holotype, CU 88085 (morpho, DNA), male, 114.8 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park, (0.62 ° N, 14.95 ° E), V. Mbossi, J.P. Friel, S. Lavoué & J.P. Sullivan coll., 16 August 2002. Paratypes. AMNH 251418 (ex CU 88096) (morpho, EOD), male, 99.9 mm SL; CU 88097 (morpho, EOD, DNA; caudal peduncle dissected by Lavoué et al. (2008) to sample electric organ for histological examination), sex undet., 95.0 mm SL; AMNH 251419 (ex CU 88098) (morpho, EOD), sex undet., 103.2 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park, (0.62 ° N, 14.95 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., 20 August, 2002. CU 87839 (morpho, EOD, DNA), male, 87.3 mm SL; CU 89188 (morpho), sex undet., 98.5 mm SL; CU 89188 (morpho, caudal peduncle dissected by Lavoué et al. (2008) to sample electric organ for histological examination, sex undet., 103.6 mm SL; CU 89188 (morpho), male, 107.4 mm SL; CU 89188 (morpho), male, 86.1 mm SL. Republic of the Congo, small channel around island in Lékoli River (Congo basin), Odzala National Park, (0.62 ° N, 14.95 ° E), V. Mbossi, J.P. Friel, S. Lavoué & J.P. Sullivan coll., 16 August 2002. Other specimens. We examined five other specimens from Odzala National Park and one from the Sangha River basin (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus pulsivertens n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with at least 25 branched rays (range = 25–27). Anal fin with at least 31 branched rays (range = 31–35). Mouth large (HL/MW ≤ 3.7, range = 3.0– 3.7). Fifteen to 21 teeth in the lower jaw; 24–30 teeth in the upper jaw. Eye large (HL/ED ≤ 3.5, range = 3.2–3.5). Pigmentation pattern consists of two distinctive melanin markings (black patches): (1) a distinct ovoid mark below the anterior base of the dorsal fin; and (2) a crescent-like mark, sometimes diffuse, centered at the base of the caudal fin and extending onto the upper and lower parts of the caudal fin. EOD appears to be inverted in polarity, with a first main phase that is negative under the standard recording geometry, resulting in a waveform that is very distinctive in comparison to all known congeners. Description. Morphometric ratios and meristic data for the holotype and paratypes are presented in Table 9. Petrocephalus pulsivertens n. sp. is a relatively large sized species within the genus Petrocephalus (maximum SL observed = 114.8 mm, the length of the holotype). Body ovoid, longer than high (2.6 ≤ SL /H ≤ 2.9, paratype average = 2.7, holotype = 2.8) and laterally compressed. Head length between 3.6 and 3.7 times in standard length (holotype = 3.7). Eye large (3.2 ≤ HL/ED ≤ 3.5, paratype average = 3.4, holotype = 3.5). Snout short (6.1 ≤ HL/SNL ≤ 7.3, paratype average = 6.5, holotype = 6.8) and round. Mouth large (3.0 ≤ HL/ MW ≤ 3.7, paratype average = 3.3, holotype = 3.0), sub-terminal, opening just under the anterior half of the eye. Teeth bicuspid, small and numerous, 15–21 (paratype average = 18, holotype = 21) in a single row in the upper jaw, 24–30 (paratype average = 28, holotype = 29) in a single row in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ≤ SL / PDD ≤ 1.7 and 1.7 ≤ SL /PAD ≤ 1.8, respectively). Predorsal distance equal to, or slightly greater than, pre-anal distance (1.0 ≤ PDD /PAD ≤ 1.1). Dorsal fin with 25– 27 branched rays (paratype median = 26, holotype = 26). Anal fin with 31–35 branched rays (paratype median = 33, holotype = 34). Scales cover the body, except for the head. Lateral line visible and complete with 38–40 pored scales along its length. Caudal peduncle relatively thin (2.1 ≤ CPL/CPD ≤ 2.3, holotype = 2.2). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation. Knollenorgan electroreceptors on head clustered into three distinct rosettes. Holotype (m) Paratypes (n= 8) Min–Max Mean Std–Dev Min–Max Median Meristic counts: Number of scale rows between the anterior base of 14 13–15 14 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 21 15–21 18 Number of teeth in the lower jaw (TLJ) 29 24–30 28 Live coloration (Fig. 11 A). Body and head mostly whitish-silvery, but head also exhibits faint metallic blue-purple iridescence. Dorsum darker than the rest of the body. Melanin patterning consists of two distinct black marks: (1) a distinct ovoid melanin mark below the anterior base of the dorsal fin on each side of the body and (2) a crescent-like melanin mark, sometimes diffuse, centered at the base of the caudal fin on each side and extending onto the upper and lower parts of the caudal fin. No black mark is present at the base of the pectoral fins. The fins themselves are mostly translucent, with the dorsal and caudal fins sometimes turning slightly yellow after formaldehyde preservation. Distribution (Fig. 1). Endemic to the Congo River basin. We collected P. pulsivertens n. sp. along the main course of the Lékoli River. This species seemed to be absent from the small tributary creeks flowing through forest or savannah when we surveyed Odzala National Park. Elsewhere, P. pulsivertens n. sp. occurs in the vicinities of Brazzaville (i.e., the Pool Malebo), the Dja River (Cameroon) and the Dzangha-Sangha region (Sangha River basin, Central African Republic) (pers. obs.), although no EOD recordings have been made of this species outside Odzala. Electric organ discharge (Fig. 11 C). The EOD waveform of P. pulsivertens n. sp., which is known only from our recordings in Odzala, resembles an inverted-polarity version of the "typical" Petrocephalus EOD. That is, the temporal sequence of electrocyte face firing known for all other Petrocephalus (i.e., firing of the posterior electrocyte face preceding firing of the anterior electrocyte face) appears to be reversed in P. pulsivertens. At high gain, however, one can see that the very first event in the EOD is a minute head-positive deflection (for an example see Fig. 3 D of Lavoué et al., 2008). This waveform feature is consistent with current from the stalks of the posterior electrocyte face (and possibly early current during the beginning of posterior face firing itself) slightly preceding anterior face firing. Despite the waveform inversion, histological examination of electrocytes of P. pulsivertens n. sp. reveals them to be type "NPp," the character state also shared by all other Petrocephalus species investigated to date. We suspect that part of the mechanism underlying the reversed ordering of major peaks in the EOD of P. pulsivertens n. sp. might involve changes in firing threshold for one or both electrocyte faces (as proposed in Lavoué et al., 2008). This interesting example of waveform inversion in Petrocephalus reminds us that careful attention must be paid to the geometry of electrodes during EOD recordings from unknown mormyrid faunas. Given its inverted-polarity appearance, the EOD of P. pulsivertens n. sp. is immediately recognizable as distinct from those of all other congeners. Based on a threshold of 1.5 % of peak-peak amplitude (and at ambient recording temperatures), the duration of the EOD of P. pulsivertens n. sp. ranges from 0.270 to 0.418 msec, falling in the range of many "typical" Petrocephalus EODs. Statistics for waveform landmarks and other EOD measurements are provided by Lavoué et al. (2008). Etymology. From the Latin " pulsus," impulse, beating; and from " vertere, " to turn, exchange. The name describes the unusual EOD waveform of P. pulsivertens n. sp. The inverted appearance of this species’ EOD is unique among all Petrocephalus recorded to date.

Petrocephalus mbossou n. sp. [Odzala field identification and in Lavoué et al. (2008): Petrocephalus sp. 11, OTU 11] Images. Fig. 13 A, photo of the live holotype (CU 92389) and Fig. 13 B, photo of the preserved holotype. Type material. Holotype, CU 92389 (morpho, EOD, DNA), sex undet., 127.2 mm SL. Republic of the Congo, Cuvette-Ouest, Lékoli River (Congo basin), small branch of the Lékoli River, only ca. 300 meters long before it re-enters into the main channel of the Lékoli (0.62 ° N, 14.91 ° E), M.E. Arnegard, V. Mbossi, E. Kinzonzi, S. Lavoué, V. Mamonekene & P.B. McIntyre coll., June 2006. Diagnosis. Petrocephalus mbossou n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with 24 branched rays. Anal fin with 26 branched rays. Mouth inferior and small (HL/MW = 4.7) with 12 teeth in a single row in the upper jaw and 14 teeth in a single row in the lower jaw. Distance from the anterior extremity of the snout to the corner of the mouth (i.e., MP) only 2.8 times in head length. Weak pigmentation pattern with the presence of two black markings on each side of the body: (1) an irregular patch below the anterior base of the dorsal fin (first ray to the sixth/seventh rays); (2) an irregularly-shaped mark centered at the base of the caudal fin that does not extend onto the rayed portions of the upper and lower caudal fin lobes. EOD of normal polarity (i.e., first major phase head-positive) and very brief duration. Unlike any other Petrocephalus species, the second headpositive phase in the EOD (P 3) is larger in amplitude than the first head positive phase (P 1). Description. This description is based on data collected solely from the holotype, which is the only specimen of this species collected to date. Table 10 provides morphometric ratios and meristic data for the holotype. Petrocephalus mbossou n. sp. is a large-sized species within the genus Petrocephalus (SL = 127.1 mm). Body ovoid, longer than high (SL /H = 3.0) and laterally compressed. Head length 3.4 times in standard length. Eye large (HL/ED = 3.7). Snout short (HL/SNL = 5.4) and round. Mouth small (HL/MW = 4.7), opening ventrally under the posterior half of the eye. Teeth small and bicuspid, 12 in a single row in the upper jaw, 14 in a single row in the lower jaw. Both the dorsal and anal fins originate in the posterior half of the body (SL / PDD = 1.7 and SL /PAD = 1.6, respectively). The pre-dorsal distance is slightly greater than the pre-anal distance. Dorsal fin with 24 branched rays. Anal fin with 26 branched rays. Scales cover the body, except for the head. Lateral line visible and complete with 37 pored scales along its length. Caudal peduncle relatively thin (CPL/CPD = 2.9) with twelve circumpeduncular scales. Skin on head thick, turning opaque with formalin fixation and containing numerous Knollenorgan electroreceptors organized into only two rosettes (the Nackenrosette and the Kehlrosette). The Augenrosette appears to be absent. Live coloration (Fig. 13 A). Body mostly white-silver. Dorsum slightly darker than the rest of the body. Pigmentation pattern consists of two distinct black markings: (1) a black patch of irregular shape below the anterior base of the dorsal fin (first ray to the sixth or seventh ray); (2) an irregularly-shaped mark centered at the base of the caudal fin that does not extend onto the rayed portions of the upper and lower caudal fin lobes. The fins themselves are translucent. Distribution (Fig. 1). Endemic to the Congo River basin. The single known specimen of this species was collected in a fish trap, which we had baited with worms and set at night in the main channel of the Lékoli River on the last day of our second trip. Electric organ discharge (Fig. 13 C). EOD recordings are only available for a single individual (the holotype), so the following description of EOD features is in need of elaboration based on additional recordings. In this single individual of P. m b o s s o u n. sp., EOD duration is very brief (0.144 msec), and the peak spectral frequency is unusually high (22.11 kHz), compared to other Petrocephalus species. In fact, duration and peak spectral frequency of this EOD recording fall outside the range observed for all other Petrocephalus individuals/species recorded in Odzala National Park (Lavoué et al., 2008). Like EODs of P. christyi, the EOD of the holotype of P. mbossou n. sp. possesses a prominent head-negative, fourth peak (P 4), the amplitude of which is 5.7 % of the waveform’s total peak-to-peak swing. However, unlike the EOD of P. christyi (as well those of all other Petrocephalus species from Odzala), the second head-positive peak (P 3) is larger than the first head-positive peak (P 1). Electrocyte anatomy is presumed to be of type "NPp" based on the EOD waveform. Etymology. The specific epithet is the name given to Petrocephalus locally in the Lingala language. Speakers of Lingala recognize Petrocephalus as a natural group, which they call " mbossou." Remarks. We opted to describe P. m b o s s o u as a new species based only on the holotype for the following reasons. This individual specimen has a unique cytb haplotype and does not belong to any putative species (consisting of two or more specimens) of Petrocephalus in our molecular phylogenetic tree, and its body form and EOD are outside the ranges observed for all other Odzala Petrocephalus specimens, as well as all type material for Petrocephalus species of the Congo and Lower Guinea provinces. In taxonomic investigations of fish faunas from more accessible regions of Africa, it is normally (and reasonably) expected that investigators collect multiple specimens before describing a new species. However, given the remote location of Odzala National Park it may be some time before additional specimens become available. This fact and this species’ distinctive morphology, EODs and DNA justify describing P. mbossou n. sp. at this time with only a single specimen.

Petrocephalus odzalaensis n. sp. [Odzala field identification and in Lavou�� et al. (2008): Petrocephalus sp. 6, OTU 6] Images. Fig. 8 A, photo of a live specimen from Odzala and Fig. 8 B, photo of the preserved holotype (CU 88048). Type material. Holotype, CU 88048 (morpho, EOD), sex undet., 92.9 mm SL. Republic of the Congo, L��k��nie River at Mboko d��barcad��re (Congo basin), Odzala National Park, (0.62 �� N, 14.90 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. Paratypes. CU 87850 (morpho, EOD), male, 90.1 mm SL; CU 87857 (morpho, EOD), male, 92.6 mm SL; CU 88050 (morpho, EOD), male, 90.4 mm SL; AMNH 251414 (ex CU 87843) (morpho, EOD), male, 87.0 mm SL; AMNH 251417 (ex CU 88056) (morpho, EOD), male, 87.6 mm SL; AMNH 251416 (ex CU 88054) (morpho, EOD), male, 97.6 mm SL; CU 88059 (morpho, EOD), male, 99.3 mm SL; AMNH 251415 (ex CU 87844) (morpho, EOD), male, 87.3 mm SL. Republic of the Congo, L��k��nie River at Mboko d��barcad��re (Congo basin), Odzala National Park, (0.62 �� N, 14.90 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. CU 88049 (morpho, EOD; caudal peduncle dissected by Lavou�� et al. (2008) to sample electric organ for histological examination), male, 93.2 mm SL. Republic of the Congo, L��k��nie River at Mboko d��barcad��re (Congo basin), Odzala National Park, (0.62 �� N, 14.90 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 12 August 2002. Holotype (o) Paratypes (n= 9) Min���Max Mean Std���Dev Min���Max Median Meristic counts: Dorsal fin branched rays (DR) 22 20���22 21 Anal fin branched rays (AR) 29 27���29 28 Number of scales in the lateral line (SLL) 38 36���38 37 Number of scale rows between the anterior base of 11 10���14 12 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 11 8���12 11 Number of teeth in the lower jaw (TLJ) 18 18���23 20 Other specimens. We examined 19 other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus odzalaensis n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin shorter than anal fin. Dorsal fin with a maximum of 22 branched rays (range = 20���22). Anal fin with a minimum of 27 branched rays (range = 27���29). Mouth sub-terminal; ratio between head length and mouth position is between 4.2 and 5.0. Eye small (3.7 ��� HL/ED ��� 4.2). Body pinkish-gray, darker dorsally, with the presence of three distinct pigmentation patches: (1) a distinct ovoid black mark situated below the anterior base of the dorsal fin on each side of the body; (2) a small black mark at the base of each pectoral fin; (3) an ovoid black mark on each side that is centered at the base of the caudal fin, not extending onto the upper and lower lobes of this fin. EOD of normal polarity, appearing triphasic at low gain, with two main phases and a small third phase. A final, fourth phase may be present, but it is always extremely small (Description. Morphometric ratios and meristic data for the holotype and paratypes are presented in Table 6. Petrocephalus odzalaensis n. sp. is a medium sized species within the genus (maximum SL observed = 99.3 mm; holotype = 92.9 mm). Body ovoid, longer than high (2.6 ��� SL /H ��� 2.9, paratype average = 2.8, holotype = 2.6) and laterally compressed. Head length between 3.7 and 4.0 times in standard length (paratype average = 3.9, holotype = 4.0). Snout short (6.2 ��� HL/SNL ��� 8.3, paratype average = 7.3, holotype = 6.6) and round. Mouth small (4.0 ��� HL/MW ��� 4.8, paratype average = 4.3, holotype = 4.3), sub-terminal, opening just under the anterior half of the eye. Teeth small and bicuspid, 8���12 in a single row in the upper jaw (paratype median = 11, holotype = 11), 18���23 in a single row in the lower jaw (paratype median = 20, holotype = 18). Dorsal and anal fins originate in the posterior half of the body (1.5 ��� SL / PDD ��� 1.6 and 1.6 ��� SL /PAD ��� 1.7, respectively). Pre-dorsal distance slightly greater than the pre���anal distance (1.0 ��� PDD /PAD ��� 1.1). Dorsal fin with 20���22 branched rays (paratype median = 21, holotype = 22). Anal fin with 27���29 branched rays (paratype median = 28, holotype = 29). Scales cover the body, except for the head. Lateral line visible and complete with 36���38 (holotype = 38) pored scales along its length. Ten to 14 scales (paratype average = 12, holotype = 11) between the anterior base of the anal fin and the lateral line. Caudal peduncle thin (1.9 ��� CPL/ CPD ��� 2.3, paratype average = 2.1, holotype = 2.1). Twelve scales around the caudal peduncle. Skin on head thick, turning opaque with formalin fixation. Knollenorgans clustered into the three distinct "rosettes" of Harder (1968). Live coloration (Fig. 8 A). Body background color pinkish-gray, darker dorsally. Pigmentation pattern consisting of three characteristic black patches: (1) a distinct ovoid black mark below the anterior base of the dorsal fin; (2) a small black mark at the base of the pectoral fin; and (3) an ovoid black mark centered at the base of the caudal fin, which does not extend onto the upper and lower lobes. Fins translucent. Distribution (Fig. 1). Endemic to the Congo basin. Abundant in Odzala. We collected P. odzalaensis n. sp. at several localities along the main course of the L��koli River and in some small tributary creeks flowing through forest. Electric organ discharge (Fig. 8 C). The EOD waveform is typical for the genus, similar to EODs produced by many other Petrocephalus species. Total EOD duration ranges from 0.231 to 0.339 msec, based on 1.5 % voltage deviations from baseline relative to peak-peak amplitude. No EOD sex differences are apparent in the specimens recorded thus far. Lavou�� et al. (2008) provide additional statistics for waveform landmarks and other EOD measurements. Histological examination confirms that electrocytes are type NPp (Lavou�� et al., 2008). Remarks. Based on museum records from the Congo basin (pers. obs.), Petrocephalus odzalaensis has been misidentified as Petrocephalus simus in several instances. The latter species is endemic to the Lower Guinea province (Lavou�� et al., 2004). Etymology. Named for Odzala National Park., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 22-25, DOI: 10.5281/zenodo.197589, {"references":["Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339.","Harder, W. (1968) Zum Aufbau der epidermalen Sinnesorgane der Mormyridae (Mormyriformes, Teleostei). Zeitschrift fur Zellforschung, 89, 212 - 224.","Lavoue, S., Hopkins, C. D. & Kamdem Toham, A. (2004) The Petrocephalus (Pisces, Osteoglossomorpha, Mormyridae) of Gabon, Central Africa, with the description of a new species. Zoosystema, 26, 511 - 535."]}

Petrocephalus valentini n. sp. [Odzala field identification and in Lavou�� et al. (2008): Petrocephalus sp. 3, OTU 3] Images. Fig. 5 A, photo of a live specimen from Odzala and Fig. 5 B, photo of the preserved holotype (CU 88117). Type material. Holotype, CU 88117 (morpho, EOD), male, 77.2 mm SL. Republic of the Congo, Cuvette-Ouest, L��koli River (Congo basin), Odzala National Park (0.62 �� N, 14.93 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan, 24 August 2002. Paratypes. CU 87828 (morpho, EOD), sex undet., 73.6 mm SL; AMNH 251420 (ex CU 87827) (morpho, EOD), male, 70.9 mm SL; AMNH 251423 (ex CU 88116) (morpho, EOD), sex undet., 64.5 mm SL; CU 88120 (morpho, EOD), sex undet., 66.7 mm SL; CU 88118 (morpho, EOD, DNA), sex undet., 58.1 mm SL. Republic of the Congo, Cuvette-Ouest, L��koli River (Congo basin), Odzala National Park (0.62 �� N, 14.93 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 24 August 2002. CU 87834 (morpho, EOD), male, 70.6 mm SL; AMNH 251422 (ex CU 88073) (morpho, EOD), sex undet., 65.9 mm SL; AMNH 251421 (ex CU 88072) (morpho, EOD), male, 72.9 mm SL. Republic of the Congo, Cuvette-Ouest, L��k��nie River at Mboko d��barcad��re, Odzala National Park (0.62 �� N, 14.91 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. Other specimens. We examined three other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus valentini n. sp. is distinguished from all other Petrocephalus species in Central Africa (i.e., Lower Guinea and Congo provinces) by the following combination of characteristics. Dorsal fin with 19���24 branched rays. Anal fin with 24���26 branched rays. Eye large (HL/ED ��� 3.2, range = 2.9���3.2). Mouth very small (HL/MW ��� 5.8, range = 4.7���5.8). Twelve teeth or fewer in the upper jaw (range = 7���12), 17 teeth or fewer in the lower jaw (range = 15���17). Pigmentation pattern subtle, including two components: (1) a pale dorsal black mark on each side of the body below the anterior base of the dorsal fin (under the second to sixth dorsal rays); (2) an ovoid mark, sometimes scarcely visible, at the base of the caudal fin, extending weakly onto the upper and lower lobes of the fin. EOD of normal polarity. Description. Morphometric ratios and meristic data are given in Table 3 for the holotype and paratypes separately. Petrocephalus valentini n. sp. is a small sized species within the genus (maximum SL = 77.2 mm, holotype). Body ovoid, longer than high (2.8 ��� SL /H ��� 3.0, paratype average = 2.9, holotype = 2.8) and laterally compressed. Head length between 3.4 and 3.7 times in standard length (paratype average = 3.6, holotype = 3.4). Snout short (6.5 ��� HL/SNL ��� 8.2, paratype average = 7.4, holotype = 6.5) and round. Mouth small (4.7 ��� HL/MW ��� 5.8, paratype average = 5.2, holotype = 5.1) and sub-terminal, positioned under the anterior half of the eye. Eye large (2.9 ��� HL/ED ��� 3.2, paratype average = 3.0, holotype = 3.1). Teeth small and bicuspid, 7���12 (paratype median = 9, holotype = 9) in a single row in the upper jaw, 15���17 (paratype median = 16, holotype = 17) in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ��� SL / PDD ��� 1.7 and SL /PAD = 1.6). Pre-dorsal distance approximately equal to the pre-anal distance. Dorsal fin with 19���24 branched rays (paratype median = 22, holotype = 22). Anal fin with 24���26 branched rays (paratype median = 25, holotype = 25). Scales cover the body, except for the head. Lateral line visible and complete with 35���36 pored scales along its length (paratype median = 36, holotype = 35). Nine to 12 scales (paratype median = 11, holotype = 11) between the anterior base of the anal fin and the lateral line. Caudal peduncle relatively thin (2.2 ��� CPL/CPD ��� 2.5, paratype average = 2.3, holotype = 2.3). Twelve scales around the caudal peduncle. Skin on head thick, turning opaque with formalin fixation. Knollenorgans clearly organized into two visible rosettes (the Augenrosette and the Nackenrosette). During our examination of specimens, we were uncertain about the definitive presence of the third rosette, the Kehlrosette, as this structure did not appear to us to be as distinct as it is in some other species (e.g., P. binotatus). Recently, however, more definitive analysis using toluidine blue staining of the skin suggests that the Kehlrosette is in fact present, but it is indeed smaller and harder to discern than in other Petrocephalus (M. Hollmann and B. A. Carlson, unpub. obs.). Holotype (m) Paratypes (n= 8) Min���Max Mean Std���Dev Min���Max Median Meristic counts: Number of scale rows between the anterior base of the 11 9���12 11 anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 9 7���12 9 Number of teeth in the lower jaw (TLJ) 17 15���17 16 Live coloration (Fig. 5 A). Body uniformly white-silver, with two faint black patches, sometimes hardly distinguishable: (1) a dorsal mark on each side of the body, below the anterior base of the dorsal fin under the second to the sixth rays; (2) an ovoid/crescent-shaped mark centered at the base of the caudal fin (sometimes the center of this second mark is less distinguishable than the two arms of the crescent), with each arm slightly extending onto the upper and lower parts of the caudal fin. There is no melanin marking at the base of the pectoral fins. Fins translucent. Distribution (Fig. 1). Apparently endemic to the Congo basin. Common in Odzala National Park. At night, we collected single specimens cruising in the main channel of the L��koli River. At the times we surveyed Odzala, P. valentini seemed absent from the small tributary creeks flowing through the park���s forest or savannah. Elsewhere in the Congo basin, P. valentini n. sp. has been collected from the Lower Congo River in the vicinity of the Pool Malebo (museum specimen records, pers. obs.). Electric organ discharge (Fig. 5 C). The EOD waveform produced by P. valentini n. sp. is similar in its characteristics to those produced by many other Petrocephalus species. EOD duration = 0.520 ��� 1.022 msec. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008). Electrocytes are assumed to be of type NPp based on the EOD waveform, although this has not been confirmed histologically. Remarks. Without careful inspection, it is possible that specimens of Petrocephalus valentini n. sp. could be misidentified as Petrocephalus catostoma or Petrocephalus simus because of the absence or near absence of pigmentation patterns in all three species. However, these three species differ from each other in several morphometric measurements and meristic counts, and their geographical distributions, as currently known, are non-overlapping. Etymology. Named in honor of Mr. Valentin Mbossi, pinassier extraordinaire at Odzala National Park. Fieldwork is as important as laboratory bench work and analysis when it comes to investigations of electric fish taxonomy, behavior and evolution. Valentin assisted us during both of our expeditions to Odzala. We use his first name for this species to reflect our appreciation of him as both colleague and friend and to avoid confusion with a similarly named species, below., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 13-16, DOI: 10.5281/zenodo.197589, {"references":["Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus mbossou n. sp. [Odzala field identification and in Lavou�� et al. (2008): Petrocephalus sp. 11, OTU 11] Images. Fig. 13 A, photo of the live holotype (CU 92389) and Fig. 13 B, photo of the preserved holotype. Type material. Holotype, CU 92389 (morpho, EOD, DNA), sex undet., 127.2 mm SL. Republic of the Congo, Cuvette-Ouest, L��koli River (Congo basin), small branch of the L��koli River, only ca. 300 meters long before it re-enters into the main channel of the L��koli (0.62 �� N, 14.91 �� E), M.E. Arnegard, V. Mbossi, E. Kinzonzi, S. Lavou��, V. Mamonekene & P.B. McIntyre coll., June 2006. Diagnosis. Petrocephalus mbossou n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with 24 branched rays. Anal fin with 26 branched rays. Mouth inferior and small (HL/MW = 4.7) with 12 teeth in a single row in the upper jaw and 14 teeth in a single row in the lower jaw. Distance from the anterior extremity of the snout to the corner of the mouth (i.e., MP) only 2.8 times in head length. Weak pigmentation pattern with the presence of two black markings on each side of the body: (1) an irregular patch below the anterior base of the dorsal fin (first ray to the sixth/seventh rays); (2) an irregularly-shaped mark centered at the base of the caudal fin that does not extend onto the rayed portions of the upper and lower caudal fin lobes. EOD of normal polarity (i.e., first major phase head-positive) and very brief duration. Unlike any other Petrocephalus species, the second headpositive phase in the EOD (P 3) is larger in amplitude than the first head positive phase (P 1). Description. This description is based on data collected solely from the holotype, which is the only specimen of this species collected to date. Table 10 provides morphometric ratios and meristic data for the holotype. Petrocephalus mbossou n. sp. is a large-sized species within the genus Petrocephalus (SL = 127.1 mm). Body ovoid, longer than high (SL /H = 3.0) and laterally compressed. Head length 3.4 times in standard length. Eye large (HL/ED = 3.7). Snout short (HL/SNL = 5.4) and round. Mouth small (HL/MW = 4.7), opening ventrally under the posterior half of the eye. Teeth small and bicuspid, 12 in a single row in the upper jaw, 14 in a single row in the lower jaw. Both the dorsal and anal fins originate in the posterior half of the body (SL / PDD = 1.7 and SL /PAD = 1.6, respectively). The pre-dorsal distance is slightly greater than the pre-anal distance. Dorsal fin with 24 branched rays. Anal fin with 26 branched rays. Scales cover the body, except for the head. Lateral line visible and complete with 37 pored scales along its length. Caudal peduncle relatively thin (CPL/CPD = 2.9) with twelve circumpeduncular scales. Skin on head thick, turning opaque with formalin fixation and containing numerous Knollenorgan electroreceptors organized into only two rosettes (the Nackenrosette and the Kehlrosette). The Augenrosette appears to be absent. Live coloration (Fig. 13 A). Body mostly white-silver. Dorsum slightly darker than the rest of the body. Pigmentation pattern consists of two distinct black markings: (1) a black patch of irregular shape below the anterior base of the dorsal fin (first ray to the sixth or seventh ray); (2) an irregularly-shaped mark centered at the base of the caudal fin that does not extend onto the rayed portions of the upper and lower caudal fin lobes. The fins themselves are translucent. Distribution (Fig. 1). Endemic to the Congo River basin. The single known specimen of this species was collected in a fish trap, which we had baited with worms and set at night in the main channel of the L��koli River on the last day of our second trip. Electric organ discharge (Fig. 13 C). EOD recordings are only available for a single individual (the holotype), so the following description of EOD features is in need of elaboration based on additional recordings. In this single individual of P. m b o s s o u n. sp., EOD duration is very brief (0.144 msec), and the peak spectral frequency is unusually high (22.11 kHz), compared to other Petrocephalus species. In fact, duration and peak spectral frequency of this EOD recording fall outside the range observed for all other Petrocephalus individuals/species recorded in Odzala National Park (Lavou�� et al., 2008). Like EODs of P. christyi, the EOD of the holotype of P. mbossou n. sp. possesses a prominent head-negative, fourth peak (P 4), the amplitude of which is 5.7 % of the waveform���s total peak-to-peak swing. However, unlike the EOD of P. christyi (as well those of all other Petrocephalus species from Odzala), the second head-positive peak (P 3) is larger than the first head-positive peak (P 1). Electrocyte anatomy is presumed to be of type "NPp" based on the EOD waveform. Etymology. The specific epithet is the name given to Petrocephalus locally in the Lingala language. Speakers of Lingala recognize Petrocephalus as a natural group, which they call " mbossou." Remarks. We opted to describe P. m b o s s o u as a new species based only on the holotype for the following reasons. This individual specimen has a unique cytb haplotype and does not belong to any putative species (consisting of two or more specimens) of Petrocephalus in our molecular phylogenetic tree, and its body form and EOD are outside the ranges observed for all other Odzala Petrocephalus specimens, as well as all type material for Petrocephalus species of the Congo and Lower Guinea provinces. In taxonomic investigations of fish faunas from more accessible regions of Africa, it is normally (and reasonably) expected that investigators collect multiple specimens before describing a new species. However, given the remote location of Odzala National Park it may be some time before additional specimens become available. This fact and this species��� distinctive morphology, EODs and DNA justify describing P. mbossou n. sp. at this time with only a single specimen., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 38-41, DOI: 10.5281/zenodo.197589, {"references":["Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Key to the Petrocephalus species of Odzala 1 Fewer than 18 branched rays (rarely 18) in the dorsal fin; only eight to 10 scale rows between the anterior base of the anal fin and the lateral line; distinct melanin markings absent on the body (i.e., absence of black patches that are species-specific for many other Petrocephalus species); rosettes of Knollenorgan electroreceptors absent on the head......................................................................................................................................... Petrocephalus microphthalmus - Usually more than 20 dorsal fin branched rays (sometimes 20; in very rare instances 19); at least 10, usually more, scale rows between the anterior base of the anal fin and the lateral line; distinct melanin markings (black patches) may be present or absent on the body; electroreceptor rosettes present or absent on the head.................................... 2 2 Mouth large, its width at most 3.9 times in head length; at least 15 teeth in the upper jaw, usually more.................. 3 - Mouth small, its width at least 3.6 times (usually 4.0��� 4.4 times) in head length; usually fewer than 15 teeth in the upper jaw (rarely 15 or 16)........................................................................................................................................... 5 3 Anal fin contains 26 or 27 branched rays; 20���22 branched rays in the dorsal fin; three intense black patches of melanin present on each side of the body: a rounded sub-dorsal mark, an ovoid caudal mark and a mark at the origin of the pectoral fin .............................................................................................................................. Petrocephalus balayi - Anal fin contains more than 30 branched rays; more than 24 branched rays in the dorsal fin; only two distinct black patches of melanin on each side of the body: a sub-dorsal mark and a caudal mark................................................... 4 4 Eye relatively small (HL/ED ��� 4.0); mouth sub-terminal (HL/MP ��� 4.4), opening under the anterior half of the eye; two distinct melanin marks present but sometimes pale: a rounded sub-dorsal mark and a crescent-like mark at the base of the caudal fin; Knollenorgan electroreceptors organized into three distinct rosettes on head, but rosettes relatively small; EOD waveform typical for the genus, polarity normal (Fig. 10 C) ....................... Petrocephalus sauvagii - Eye large (HL/ED ��� 3.5); mouth sub-terminal but positioned more caudally along the ventral margin of the head (HL/MP ��� 3.5), opening under the posterior half of the eye; two distinct melanin marks: a rounded, sometimes irregularly shaped, sub���dorsal black mark and a crescent-like black mark at the base of the caudal fin; three larger rosettes of Knollenorgan electroreceptors present on the head; EOD waveform very distinctive among congeners, appearing to be reversed in polarity compared to EODs of all other Petrocephalus species (Fig. 11 C)........................ ................................................................................................................................... Petrocephalus pulsiverten s n. sp. 5 Anal fin contains 30 or more branched rays; melanin markings (black patches) present on the body and always distinctly visible................................................................................................................................................................. 6 - Anal fin contains at most 29 branched rays (usually fewer); melanin markings present but sometimes hardly visible...................................................................................................................................................................................... 7 6 Dorsal fin contains 24���26 branched rays; eye large (HL/ED ��� 3.2); mouth very small relative to many congeners (HL/MW ��� 5.2); two melanin marks present and distinct but of medium intensity: a rounded sub-dorsal mark and a crescent-like mark at the base of the caudal fin; two readily observed rosettes of Knollenorgan electroreceptors present on the head (Augenrosette and Nackenrosette) plus a Kehlrosette that is rather difficult to observe without staining........................................................................................................................................ Petrocephalus grandoculis - Dorsal fin contains 24 (holotype) or fewer (Odzala specimens) branched rays; eye smaller in size (3.5 ��� HL/ED ��� 4.0); mouth larger (HL/MW ��� 5.2); three distinct melanin marks (black patches) present: an ovoid sub-dorsal mark (sometimes small and covering few scales, but always intense), an ovoid caudal mark and a mark at the origin of the pectoral fin; all three electroreceptor rosettes present on the head and distinct...................... Petrocephalus binotatus 7 Melanin markings on body intensely black with sharply defined edges, forming characteristic shapes (e.g., very rounded black sub-dorsal spot or saddle-like sub-dorsal patch, crescent shaped black mark at the base of the caudal fin or round black spot at the caudal fin base).............................................................................................................. 8 - Melanin markings of much weaker intensity, consisting of more irregularly���shaped patches and with comparatively diffuse edges............................................................................................................................................................... 10 8 Small but intense black mark present on each side of the body at the pectoral fin origin; Knollenorgan electroreceptors on the head may or may not be arranged into discrete clusters (i.e., rosettes may be present or absent), but if rosettes are present the Augenrosette is always as well developed as the other rosettes.............................................. 9 - No distinct black mark visible at the origin of the pectoral fin; electroreceptors organized into three distinct rosettes on the head, but the Augenrosette is small and not as well developed as the other rosettes...... Petrocephalus christyi 9 Eye large (HL/ED ��� 3.3); sub-dorsal black patch often contacting the contralateral mark over dorsum and most anterior branched rays of the dorsal fin; caudal melanin marking forming a rather uniformly shaped crescent (or "V") that extends onto the upper and lower fleshy lobes of the caudal fin; Knollenorgan electroreceptors on the head are not clustered into discrete groups (i.e., rosettes absent)...................................................... Petrocephalus zakoni n. sp. - Eye small (HL/ED ��� 3.7); sub-dorsal black patch distinctly rounded, never in contact with the contralateral mark and not extending onto the dorsal fin; caudal mark ovoid rather than crescent- or V-shaped, not extending onto the upper and lower parts of the caudal fin; Knollenorgans on the head are clustered into three rosettes.............................................................................................................................................................. Petrocephalus odzalaensis n. sp. 10 Mouth sub-terminal, opening under the anterior half of the eye; snout short (HL/SNL ��� 6.5); Knollenorgan electroreceptors on the head are clustered into three rosettes (but a distinctive Kehlrosette is difficult to observe without staining); EOD of normal polarity, often appearing to have an overall biphasic waveform at low gain, although a minute third peak is in fact present (first head-positive peak, P 1, much larger in amplitude than second head-positive peak, P 3, which never exceeds 10 % of total peak-to-peak amplitude) ........................... Petrocephalus valentini n. sp. - Mouth sub-terminal but positioned more caudally along the ventral margin of the head, opening under the posterior half of the eye; snout somewhat longer (HL/SNL = 5.4 in the single specimen available, the holotype); Knollenorgans on the head are clustered into only two rosettes (the Nackenrosette and the Kehlrosette), Augenrosette absent; EOD of normal polarity, with more than two phases apparent even at low gain (the only specimen of this species that has been recorded exhibits an EOD containing 4 peaks; the second head-positive peak, P 3, is larger in amplitude than the first head-positive peak, P 1; amplitude of P 3 substantially greater than 10 % of total peak-to-peak amplitude) ................................................................................................................................ Petrocephalus mbossou n. sp., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 45-46, DOI: 10.5281/zenodo.197589

Petrocephalus valentini n. sp. [Odzala field identification and in Lavoué et al. (2008): Petrocephalus sp. 3, OTU 3] Images. Fig. 5 A, photo of a live specimen from Odzala and Fig. 5 B, photo of the preserved holotype (CU 88117). Type material. Holotype, CU 88117 (morpho, EOD), male, 77.2 mm SL. Republic of the Congo, Cuvette-Ouest, Lékoli River (Congo basin), Odzala National Park (0.62 ° N, 14.93 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan, 24 August 2002. Paratypes. CU 87828 (morpho, EOD), sex undet., 73.6 mm SL; AMNH 251420 (ex CU 87827) (morpho, EOD), male, 70.9 mm SL; AMNH 251423 (ex CU 88116) (morpho, EOD), sex undet., 64.5 mm SL; CU 88120 (morpho, EOD), sex undet., 66.7 mm SL; CU 88118 (morpho, EOD, DNA), sex undet., 58.1 mm SL. Republic of the Congo, Cuvette-Ouest, Lékoli River (Congo basin), Odzala National Park (0.62 ° N, 14.93 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., 24 August 2002. CU 87834 (morpho, EOD), male, 70.6 mm SL; AMNH 251422 (ex CU 88073) (morpho, EOD), sex undet., 65.9 mm SL; AMNH 251421 (ex CU 88072) (morpho, EOD), male, 72.9 mm SL. Republic of the Congo, Cuvette-Ouest, Lékénie River at Mboko débarcadère, Odzala National Park (0.62 ° N, 14.91 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. Other specimens. We examined three other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus valentini n. sp. is distinguished from all other Petrocephalus species in Central Africa (i.e., Lower Guinea and Congo provinces) by the following combination of characteristics. Dorsal fin with 19–24 branched rays. Anal fin with 24–26 branched rays. Eye large (HL/ED ≤ 3.2, range = 2.9–3.2). Mouth very small (HL/MW ≤ 5.8, range = 4.7–5.8). Twelve teeth or fewer in the upper jaw (range = 7–12), 17 teeth or fewer in the lower jaw (range = 15–17). Pigmentation pattern subtle, including two components: (1) a pale dorsal black mark on each side of the body below the anterior base of the dorsal fin (under the second to sixth dorsal rays); (2) an ovoid mark, sometimes scarcely visible, at the base of the caudal fin, extending weakly onto the upper and lower lobes of the fin. EOD of normal polarity. Description. Morphometric ratios and meristic data are given in Table 3 for the holotype and paratypes separately. Petrocephalus valentini n. sp. is a small sized species within the genus (maximum SL = 77.2 mm, holotype). Body ovoid, longer than high (2.8 ≤ SL /H ≤ 3.0, paratype average = 2.9, holotype = 2.8) and laterally compressed. Head length between 3.4 and 3.7 times in standard length (paratype average = 3.6, holotype = 3.4). Snout short (6.5 ≤ HL/SNL ≤ 8.2, paratype average = 7.4, holotype = 6.5) and round. Mouth small (4.7 ≤ HL/MW ≤ 5.8, paratype average = 5.2, holotype = 5.1) and sub-terminal, positioned under the anterior half of the eye. Eye large (2.9 ≤ HL/ED ≤ 3.2, paratype average = 3.0, holotype = 3.1). Teeth small and bicuspid, 7–12 (paratype median = 9, holotype = 9) in a single row in the upper jaw, 15–17 (paratype median = 16, holotype = 17) in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ≤ SL / PDD ≤ 1.7 and SL /PAD = 1.6). Pre-dorsal distance approximately equal to the pre-anal distance. Dorsal fin with 19–24 branched rays (paratype median = 22, holotype = 22). Anal fin with 24–26 branched rays (paratype median = 25, holotype = 25). Scales cover the body, except for the head. Lateral line visible and complete with 35–36 pored scales along its length (paratype median = 36, holotype = 35). Nine to 12 scales (paratype median = 11, holotype = 11) between the anterior base of the anal fin and the lateral line. Caudal peduncle relatively thin (2.2 ≤ CPL/CPD ≤ 2.5, paratype average = 2.3, holotype = 2.3). Twelve scales around the caudal peduncle. Skin on head thick, turning opaque with formalin fixation. Knollenorgans clearly organized into two visible rosettes (the Augenrosette and the Nackenrosette). During our examination of specimens, we were uncertain about the definitive presence of the third rosette, the Kehlrosette, as this structure did not appear to us to be as distinct as it is in some other species (e.g., P. binotatus). Recently, however, more definitive analysis using toluidine blue staining of the skin suggests that the Kehlrosette is in fact present, but it is indeed smaller and harder to discern than in other Petrocephalus (M. Hollmann and B. A. Carlson, unpub. obs.). Holotype (m) Paratypes (n= 8) Min–Max Mean Std–Dev Min–Max Median Meristic counts: Number of scale rows between the anterior base of the 11 9–12 11 anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 9 7–12 9 Number of teeth in the lower jaw (TLJ) 17 15–17 16 Live coloration (Fig. 5 A). Body uniformly white-silver, with two faint black patches, sometimes hardly distinguishable: (1) a dorsal mark on each side of the body, below the anterior base of the dorsal fin under the second to the sixth rays; (2) an ovoid/crescent-shaped mark centered at the base of the caudal fin (sometimes the center of this second mark is less distinguishable than the two arms of the crescent), with each arm slightly extending onto the upper and lower parts of the caudal fin. There is no melanin marking at the base of the pectoral fins. Fins translucent. Distribution (Fig. 1). Apparently endemic to the Congo basin. Common in Odzala National Park. At night, we collected single specimens cruising in the main channel of the Lékoli River. At the times we surveyed Odzala, P. valentini seemed absent from the small tributary creeks flowing through the park’s forest or savannah. Elsewhere in the Congo basin, P. valentini n. sp. has been collected from the Lower Congo River in the vicinity of the Pool Malebo (museum specimen records, pers. obs.). Electric organ discharge (Fig. 5 C). The EOD waveform produced by P. valentini n. sp. is similar in its characteristics to those produced by many other Petrocephalus species. EOD duration = 0.520 – 1.022 msec. Statistics for waveform landmarks and other EOD measurements are provided by Lavoué et al. (2008). Electrocytes are assumed to be of type NPp based on the EOD waveform, although this has not been confirmed histologically. Remarks. Without careful inspection, it is possible that specimens of Petrocephalus valentini n. sp. could be misidentified as Petrocephalus catostoma or Petrocephalus simus because of the absence or near absence of pigmentation patterns in all three species. However, these three species differ from each other in several morphometric measurements and meristic counts, and their geographical distributions, as currently known, are non-overlapping. Etymology. Named in honor of Mr. Valentin Mbossi, pinassier extraordinaire at Odzala National Park. Fieldwork is as important as laboratory bench work and analysis when it comes to investigations of electric fish taxonomy, behavior and evolution. Valentin assisted us during both of our expeditions to Odzala. We use his first name for this species to reflect our appreciation of him as both colleague and friend and to avoid confusion with a similarly named species, below.

Key to the Petrocephalus species of Odzala 1 Fewer than 18 branched rays (rarely 18) in the dorsal fin; only eight to 10 scale rows between the anterior base of the anal fin and the lateral line; distinct melanin markings absent on the body (i.e., absence of black patches that are species-specific for many other Petrocephalus species); rosettes of Knollenorgan electroreceptors absent on the head......................................................................................................................................... Petrocephalus microphthalmus - Usually more than 20 dorsal fin branched rays (sometimes 20; in very rare instances 19); at least 10, usually more, scale rows between the anterior base of the anal fin and the lateral line; distinct melanin markings (black patches) may be present or absent on the body; electroreceptor rosettes present or absent on the head.................................... 2 2 Mouth large, its width at most 3.9 times in head length; at least 15 teeth in the upper jaw, usually more.................. 3 - Mouth small, its width at least 3.6 times (usually 4.0– 4.4 times) in head length; usually fewer than 15 teeth in the upper jaw (rarely 15 or 16)........................................................................................................................................... 5 3 Anal fin contains 26 or 27 branched rays; 20–22 branched rays in the dorsal fin; three intense black patches of melanin present on each side of the body: a rounded sub-dorsal mark, an ovoid caudal mark and a mark at the origin of the pectoral fin .............................................................................................................................. Petrocephalus balayi - Anal fin contains more than 30 branched rays; more than 24 branched rays in the dorsal fin; only two distinct black patches of melanin on each side of the body: a sub-dorsal mark and a caudal mark................................................... 4 4 Eye relatively small (HL/ED ≥ 4.0); mouth sub-terminal (HL/MP ≥ 4.4), opening under the anterior half of the eye; two distinct melanin marks present but sometimes pale: a rounded sub-dorsal mark and a crescent-like mark at the base of the caudal fin; Knollenorgan electroreceptors organized into three distinct rosettes on head, but rosettes relatively small; EOD waveform typical for the genus, polarity normal (Fig. 10 C) ....................... Petrocephalus sauvagii - Eye large (HL/ED ≤ 3.5); mouth sub-terminal but positioned more caudally along the ventral margin of the head (HL/MP ≤ 3.5), opening under the posterior half of the eye; two distinct melanin marks: a rounded, sometimes irregularly shaped, sub–dorsal black mark and a crescent-like black mark at the base of the caudal fin; three larger rosettes of Knollenorgan electroreceptors present on the head; EOD waveform very distinctive among congeners, appearing to be reversed in polarity compared to EODs of all other Petrocephalus species (Fig. 11 C)........................ ................................................................................................................................... Petrocephalus pulsiverten s n. sp. 5 Anal fin contains 30 or more branched rays; melanin markings (black patches) present on the body and always distinctly visible................................................................................................................................................................. 6 - Anal fin contains at most 29 branched rays (usually fewer); melanin markings present but sometimes hardly visible...................................................................................................................................................................................... 7 6 Dorsal fin contains 24–26 branched rays; eye large (HL/ED ≤ 3.2); mouth very small relative to many congeners (HL/MW ≥ 5.2); two melanin marks present and distinct but of medium intensity: a rounded sub-dorsal mark and a crescent-like mark at the base of the caudal fin; two readily observed rosettes of Knollenorgan electroreceptors present on the head (Augenrosette and Nackenrosette) plus a Kehlrosette that is rather difficult to observe without staining........................................................................................................................................ Petrocephalus grandoculis - Dorsal fin contains 24 (holotype) or fewer (Odzala specimens) branched rays; eye smaller in size (3.5 ≤ HL/ED ≤ 4.0); mouth larger (HL/MW ≤ 5.2); three distinct melanin marks (black patches) present: an ovoid sub-dorsal mark (sometimes small and covering few scales, but always intense), an ovoid caudal mark and a mark at the origin of the pectoral fin; all three electroreceptor rosettes present on the head and distinct...................... Petrocephalus binotatus 7 Melanin markings on body intensely black with sharply defined edges, forming characteristic shapes (e.g., very rounded black sub-dorsal spot or saddle-like sub-dorsal patch, crescent shaped black mark at the base of the caudal fin or round black spot at the caudal fin base).............................................................................................................. 8 - Melanin markings of much weaker intensity, consisting of more irregularly–shaped patches and with comparatively diffuse edges............................................................................................................................................................... 10 8 Small but intense black mark present on each side of the body at the pectoral fin origin; Knollenorgan electroreceptors on the head may or may not be arranged into discrete clusters (i.e., rosettes may be present or absent), but if rosettes are present the Augenrosette is always as well developed as the other rosettes.............................................. 9 - No distinct black mark visible at the origin of the pectoral fin; electroreceptors organized into three distinct rosettes on the head, but the Augenrosette is small and not as well developed as the other rosettes...... Petrocephalus christyi 9 Eye large (HL/ED ≤ 3.3); sub-dorsal black patch often contacting the contralateral mark over dorsum and most anterior branched rays of the dorsal fin; caudal melanin marking forming a rather uniformly shaped crescent (or "V") that extends onto the upper and lower fleshy lobes of the caudal fin; Knollenorgan electroreceptors on the head are not clustered into discrete groups (i.e., rosettes absent)...................................................... Petrocephalus zakoni n. sp. - Eye small (HL/ED ≥ 3.7); sub-dorsal black patch distinctly rounded, never in contact with the contralateral mark and not extending onto the dorsal fin; caudal mark ovoid rather than crescent- or V-shaped, not extending onto the upper and lower parts of the caudal fin; Knollenorgans on the head are clustered into three rosettes.............................................................................................................................................................. Petrocephalus odzalaensis n. sp. 10 Mouth sub-terminal, opening under the anterior half of the eye; snout short (HL/SNL ≥ 6.5); Knollenorgan electroreceptors on the head are clustered into three rosettes (but a distinctive Kehlrosette is difficult to observe without staining); EOD of normal polarity, often appearing to have an overall biphasic waveform at low gain, although a minute third peak is in fact present (first head-positive peak, P 1, much larger in amplitude than second head-positive peak, P 3, which never exceeds 10 % of total peak-to-peak amplitude) ........................... Petrocephalus valentini n. sp. - Mouth sub-terminal but positioned more caudally along the ventral margin of the head, opening under the posterior half of the eye; snout somewhat longer (HL/SNL = 5.4 in the single specimen available, the holotype); Knollenorgans on the head are clustered into only two rosettes (the Nackenrosette and the Kehlrosette), Augenrosette absent; EOD of normal polarity, with more than two phases apparent even at low gain (the only specimen of this species that has been recorded exhibits an EOD containing 4 peaks; the second head-positive peak, P 3, is larger in amplitude than the first head-positive peak, P 1; amplitude of P 3 substantially greater than 10 % of total peak-to-peak amplitude) ................................................................................................................................ Petrocephalus mbossou n. sp.

Petrocephalus christyi Boulenger, 1920 Petrocephalus christyi Boulenger (1920): 11. [Odzala field identification: Petrocephalus sp. 7, OTU 7] Images. Fig. 9 A, photo of a live specimen from Odzala, Fig. 9 B, photo of a preserved specimen from Odzala and Fig. 14, drawing of a syntype from Boulenger (1920), p. 11. Additional photo of a syntype in Harder (2000). Type material. Syntypes, MRAC 7145���7151 [five of seven specimens examined]. Democratic Republic of the Congo, Congo basin, tributary Lindi at Bosabangui [in the vicinity of Kisangani, estimated 0.53 N, 25.19 E], C. Christy coll. [Note that no holotype was designated in the original description of P. christyi.] Other specimens. We examined two specimens from Odzala National Park and 16 additional specimens from the Sangha River and the Lower Congo River in the vicinity of the Pool Malebo (see specimen list provided in the section "additional material examined"). Syntypes Specimens Specimens from (n= 5) from Odzala Lower Congo and (n= 2) the Sangha River (n= 16) Diagnosis. The following diagnosis is based on all examined specimens of P. christyi, regardless their geographic origins. Petrocephalus christyi is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with 22���24 branched rays. Anal fin with 25���29 branched rays. Eye large (HL/ED ��� 4.2, range = 3.1���4.2). Mouth small (HL/MW ��� 2.9, range = 2.9��� 5.5, but see remarks). Nine to 13 teeth in the upper jaw, 17���22 teeth in the lower jaw. Melanin patterning consisting of two characteristic black patches: (1) a distinct round mark below the anterior base (first to the fifth rays) of the dorsal fin; and (2) a somewhat diffuse crescent-like mark, centered at the base of the caudal fin and extending onto the fleshy dorsal and ventral lobes of this fin. In the small number of individuals recorded so far, the EOD is of normal polarity, with four phases and a relatively slow initial rise. Description. Morphometric and meristic data for the syntypes, non-type specimens from Odzala and specimens from Lower Congo are separately presented in Table 7. However, the following description corresponds only to the new material collected from Odzala National Park, except where separate reference is made to the Lindi River syntypes. Petrocephalus christyi is a medium-sized species within the genus (maximum SL observed in Odzala = 84.7 mm; maximum SL observed in the syntypes = 100.0 mm). Body ovoid, longer than high (2.7 ��� SL /H ��� 2.9, syntypes = 3.0��� 3.2) and laterally compressed. Head length between 3.2 and 3.5 times in standard length (syntypes = 3.5���3.7). Snout of intermediate size (5.3 ��� HL/SNL ��� 6.3, syntypes = 5.3���5.7) and round. Eye large (3.2 ��� HL/ED ��� 3.4, syntypes = 3.1���3.8). Mouth small (4.1 ��� HL/ MW ��� 4.3, syntypes = 4.7���5.5), sub-terminal, opening just under the anterior half of the eye. Teeth small and bicuspid, 9 or 10 in a single row in the upper jaw, 19���21 in the lower jaw. Dorsal and anal fins originate in the posterior half of the body, with pre-dorsal distance equal to pre-anal distance (SL / PDD = 1.6 and SL /PAD = 1.6). Dorsal fin with 22 or 23 branched rays (syntypes = 23 or 24). Anal fin with 25 or 26 branched rays (syntypes = 26 or 27). Scales cover the body, except for the head. Lateral line visible and complete with 35���37 (syntypes = 35���39) pored scales along its length. Fourteen to 15 scales (syntypes = 13 or 14) between the anterior base of the anal fin and the lateral line. Caudal peduncle relatively thin (2.5 ��� CPL/CPD ��� 2.6, syntypes = 2.5 ���3.0). Twelve scales around the caudal peduncle. Skin on head thick, turning opaque with formalin fixation, with numerous electroreceptors organized into three distinct rosettes. However, the Augenrosette (above the eye) is not as developed as it is in the other species of Petrocephalus exhibiting this rosette. Live coloration (Fig. 9 A). Body uniformly white-silver, with the presence of two characteristic melanin marks: (1) a distinct round mark below the anterior base (first to fifth rays) of the dorsal fin; (2) a rather diffuse crescent-like mark, centered at the base of the caudal fin and extending onto the upper and lower fleshy lobes of this fin. The fins themselves are translucent. Distribution (Fig. 1). Endemic to the Congo River basin. The type specimens were collected at the locality Bosabangui along the Lindi River, which is close to the city of Kisangani. Petrocephalus christyi seems to be rare in Odzala, where we only collected it in the main channel of the L��koli River at night. In contrast, Petrocephalus christyi seems to be abundant in the vicinity of the Pool Malebo (Lower Congo). Electric organ discharge (Fig. 9 C). Bearing in mind that recordings are only available for two specimens collected within Odzala, the EOD of this species does appear to be distinctive. The EOD exhibits normal polarity and is four-phasic with a large, negative-going P 2 and smaller peaks, P 1, P 3 and P 4 [see Lavou�� et al. (2008) for definitions of these waveform landmarks]. Similar to the EODs of the Odzala population of P. microphthalmus, a relatively long, slow rise occurs during the initial part of the first head-positive phase in the EODs of both individuals of P. christyi. This rise toward P 1 has a shoulder-like inflection point, which at magnified gain is seen to possess a small, negative-going local peak. Both the slow rise and inflection point are subtle features of the EOD; they are only visible in amplified traces. Unlike the EODs of P. microphthalmus, however, those of the two P. christyi individuals possess a prominent head-negative fourth peak (P 4), the amplitude of which is 4.5 ��� 8.6 % of the waveform���s total peak-to-peak swing. A prominent P 4 is also present in the EOD emitted by the only individual of Petrocephalus mbossou n. sp. ever recorded (see below), but otherwise a P 4 seems to be rare in Petrocephalus. Based on 1.5 % voltage deviations from baseline relative to peak-peak amplitude and at ambient recording temperatures, duration of the EOD is between 0.284 and 0.390 msec in P. christyi, falling in the range of many other Petrocephalus species. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008). Electrocyte anatomy is presumed to be of type NPp based on the EOD waveform, but this has not yet been confirmed histologically. Remarks. Specimens of P. christyi from Odzala appear to differ notably from the syntypes of P. christyi (from the Lindi River, Fig. 1) in only a single aspect of morphological variation: mouth size. The syntypes have smaller mouths than the Odzala specimens (SL /MW = 17.7���20.1 in the syntypes versus 13.6���14.3 in the Odzala specimens; see also the HL/MW ratios in Table 7). Interestingly, specimens from the Lower Congo in the vicinity of the Pool Malebo (Table 7) all have mouths similar in relative size to those of the Odzala specimens. The magnitude of divergence in mouth size relative to the syntypes, and the fact that divergence in this character is consistent for both Odzala and Lower Congo specimens, suggests that populations from these sites may represent a distinct species from the P. christyi type material. A sound evaluation of this possible difference requires additional material from other Congo River sites. Until such material becomes available, we conservatively assign the Odzala and Lower Congo specimens described herein to P. christyi., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 25-29, DOI: 10.5281/zenodo.197589, {"references":["Boulenger, G. A. (1920) Poissons recueillis au Congo Belge par l'expedition du Dr C. Christy. Materiaux pour la faune du Congo. Annales du Musee du Congo, Zoologie, 2, 1 - 38.","Harder, W. (2000) Mormyridae and other Osteoglossomorpha. World Biodiversity database, CD - ROM series, ETI BioInformatics, Amsterdam.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus binotatus Pellegrin, 1924 Petrocephalus binotatus Pellegrin (1924): 1. [Odzala field identification: Petrocephalus sp. 1, OTU 1] Images. Fig. 3 A, photo of a live specimen from Odzala, Fig. 3 B, photo of a preserved specimen from Odzala and Fig. 14, drawing of the holotype (MRAC 15191) from Pellegrin (1928), p. 12. Photo of the holotype in Harder (2000). Type material. Holotype, MRAC 15191 [examined], sex undet., 83.2 mm SL. Democratic Republic of the Congo, Congo River at Ikengo [estimated geographic coordinates: 0.13 �� S, 18.13 �� E], H. Schouteden coll. Other specimens. We have examined 35 additional specimens from Odzala National Park (see "additional material examined"). Diagnosis. The following diagnosis is based on all examined specimens of P. binotatus, regardless their geographic origins. Petrocephalus binotatus is distinguished from all other Petrocephalus species from Lower Guinea and Congo provinces by the following combination of characteristics. Dorsal fin shorter than the anal fin (1.5 ��� AFL/DFL, range = 1.5���1.7). Dorsal fin with at least 20 branched rays (range = 20���24). Anal fin with at least 30 branched rays (range = 30���33). Sixteen teeth or fewer (range = 8���16) in the upper jaw, 24 teeth or fewer (range = 19���24) in the lower jaw. Eye relatively large (HL/ED ��� 4.0, range = 3.5 ���4.0). Mouth sub-terminal; ratio of head length to mouth position (HL/MP) between 3.9 and 6.1. Unique pigmentation pattern with the presence of three well defined black patches: (1) a distinct (although sometimes covering only few scales), more or less round/oval, black mark situated slightly anterior to the dorsal fin on each side of the body; (2) a black mark at the base of each pectoral fin; (3) an ovoid black mark centered at the base of the caudal fin that does not extend onto the upper and lower fleshy lobes of this fin. EOD of normal polarity (i.e., first major phase head-positive). Description. This description corresponds to the Odzala material (e.g., ranges, averages, medians), except where explicit reference is made to the holotype (from Ikengo). Morphometric ratios and meristic data for non-type specimens from Odzala and the holotype are presented in Table 1. Petrocephalus binotatus, described by Pellegrin (1924), is a small sized species within the genus Petrocephalus (maximum SL observed in Odzala = 88.4 mm, holotype = 83.2 mm). Body ovoid, longer than high (2.3 ��� SL /H ��� 2.8, average = 2.5, holotype = 2.4) and laterally compressed. Head length of Odzala specimens between 3.7 and 4.0 times in standard length (average = 3.9, holotype = 3.6). Snout short (6.8 ��� HL/SNL ��� 8.3, average = 7.8, holotype = 5.5) and round. Eye large (3.5 ��� HL/ED ��� 4.0, average = 3.6, holotype = 3.6). Mouth small (4.4 ��� HL/MW ��� 5.2, average = 4.7, holotype = 3.2), sub-terminal, opening under the anterior half of the eye. Teeth small and bicuspid, 8 to 16 (median = 10) in a single row in the upper jaw, 19 to 24 (median = 21) in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.5 ��� SL / PDD ��� 1.6) and (1.6 ��� SL /PAD ��� 1.7), respectively. Pre-dorsal distance slightly greater than the pre-anal distance (1.0 Live coloration (Fig. 3 A). Body uniformly white-silver, with the presence of three characteristic melanin marks on each side of the body: (1) a distinct, approximately round/oval black mark situated slightly anterior to the dorsal fin, sometimes covering only a few scales; (2) a black spot at the base of the pectoral fin; (3) an ovoid black mark centered at the base of the caudal fin that does not extend onto the upper and lower parts of the caudal fin. Fins translucent. Distribution (Fig. 1). Apparently endemic to the Congo River basin. Holotype from the locality Ikengo on the Congo River just below Mbandaka. One of the most abundant Petrocephalus species in Odzala. We collected P. binotatus at several localities along the main channel of the L��koli River. At the time of our collections, however, this species appeared to be absent from small tributary creeks flowing through the forest or savannah. Petrocephalus binotatus was absent in two recent collections from the Lower Congo River made in the vicinities of the Pool Malebo (one collection by M. Stiassny and B. Schelly in 2002, housed in the American Museum of Natural History; the other by P. Feulner and F. Kirschbaum in 2006, housed in the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin; pers. obs. of material contained in these collections). Electric organ discharge (Fig. 3 C). Petrocephalus binotatus males and females produce EODs with overall waveforms that are typical for the genus, being similar to EODs produced by many other congeners. However, this is one of the few Petrocephalus species (e.g., the only Petrocephalus species in Odzala National Park) for which possible EOD sex differences have been detected thus far in field recordings. As with other Petrocephalus species exhibiting possible sex differences, magnitudes of the differences between males and females are small. In Odzala, for example, mean EOD duration (�� std. dev.) is 0.330 �� 0.074 msec in obvious adult males and 0.270 �� 0.033 msec in other adult and sub-adult individuals, based on 1.5 % voltage deviations from baseline relative to peak-peak amplitude. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008) for specimens recorded in Odzala National Park. No EOD recordings are available for the holotype or other specimens collected near the type locality (Ikengo, Congo River, Fig. 1). Electrocytes are assumed to be of type NPp based on characteristics of the EOD, although electrocyte anatomy has not yet been confirmed histologically. Remarks. Specimens of P. binotatus from Odzala resemble the holotype described from the main channel of the Congo River (locality Ikengo, Fig. 1) (Pellegrin, 1924). However, they also exhibit several differences, mainly in head morphology. The holotype has a larger mouth (HL/MW = 3.2 versus ��� 4.4 in Odzala specimens), a longer snout (HL/SNL = 5.5 versus ��� 6.8 in Odzala specimens) and a larger interorbital width (HL/IOW = 2.3 versus ��� 2.6 in Odzala specimens). Additional comparative material from the type locality and other localities in the Congo basin are necessary to determine the taxonomic implications of these differences., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 6-9, DOI: 10.5281/zenodo.197589, {"references":["Pellegrin, J. (1924) Description de Mormyrides nouveaux recoltes au Congo belge par le Dr. Schouteden. Revue de Zoologie Africaine, 12, 1 - 8.","Pellegrin, J. (1928) Poissons du Chiloango et du Congo recueillis par l'expedition du Dr. H. Schouteden (1920 - 22). Annales du Musee du Congo, Zoologie, 3, 1 - 50.","Harder, W. (2000) Mormyridae and other Osteoglossomorpha. World Biodiversity database, CD - ROM series, ETI BioInformatics, Amsterdam.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus pulsivertens n. sp. [Odzala field identification and in Lavou�� et al (2008): Petrocephalus sp. 9, OTU 9] Images. Fig. 11 A, photo of a live specimen from Odzala and Fig. 11 B, photo of the preserved holotype (CU 88085). Type material. Holotype, CU 88085 (morpho, DNA), male, 114.8 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park, (0.62 �� N, 14.95 �� E), V. Mbossi, J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 16 August 2002. Paratypes. AMNH 251418 (ex CU 88096) (morpho, EOD), male, 99.9 mm SL; CU 88097 (morpho, EOD, DNA; caudal peduncle dissected by Lavou�� et al. (2008) to sample electric organ for histological examination), sex undet., 95.0 mm SL; AMNH 251419 (ex CU 88098) (morpho, EOD), sex undet., 103.2 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park, (0.62 �� N, 14.95 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 20 August, 2002. CU 87839 (morpho, EOD, DNA), male, 87.3 mm SL; CU 89188 (morpho), sex undet., 98.5 mm SL; CU 89188 (morpho, caudal peduncle dissected by Lavou�� et al. (2008) to sample electric organ for histological examination, sex undet., 103.6 mm SL; CU 89188 (morpho), male, 107.4 mm SL; CU 89188 (morpho), male, 86.1 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park, (0.62 �� N, 14.95 �� E), V. Mbossi, J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 16 August 2002. Other specimens. We examined five other specimens from Odzala National Park and one from the Sangha River basin (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus pulsivertens n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with at least 25 branched rays (range = 25���27). Anal fin with at least 31 branched rays (range = 31���35). Mouth large (HL/MW ��� 3.7, range = 3.0��� 3.7). Fifteen to 21 teeth in the lower jaw; 24���30 teeth in the upper jaw. Eye large (HL/ED ��� 3.5, range = 3.2���3.5). Pigmentation pattern consists of two distinctive melanin markings (black patches): (1) a distinct ovoid mark below the anterior base of the dorsal fin; and (2) a crescent-like mark, sometimes diffuse, centered at the base of the caudal fin and extending onto the upper and lower parts of the caudal fin. EOD appears to be inverted in polarity, with a first main phase that is negative under the standard recording geometry, resulting in a waveform that is very distinctive in comparison to all known congeners. Description. Morphometric ratios and meristic data for the holotype and paratypes are presented in Table 9. Petrocephalus pulsivertens n. sp. is a relatively large sized species within the genus Petrocephalus (maximum SL observed = 114.8 mm, the length of the holotype). Body ovoid, longer than high (2.6 ��� SL /H ��� 2.9, paratype average = 2.7, holotype = 2.8) and laterally compressed. Head length between 3.6 and 3.7 times in standard length (holotype = 3.7). Eye large (3.2 ��� HL/ED ��� 3.5, paratype average = 3.4, holotype = 3.5). Snout short (6.1 ��� HL/SNL ��� 7.3, paratype average = 6.5, holotype = 6.8) and round. Mouth large (3.0 ��� HL/ MW ��� 3.7, paratype average = 3.3, holotype = 3.0), sub-terminal, opening just under the anterior half of the eye. Teeth bicuspid, small and numerous, 15���21 (paratype average = 18, holotype = 21) in a single row in the upper jaw, 24���30 (paratype average = 28, holotype = 29) in a single row in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ��� SL / PDD ��� 1.7 and 1.7 ��� SL /PAD ��� 1.8, respectively). Predorsal distance equal to, or slightly greater than, pre-anal distance (1.0 ��� PDD /PAD ��� 1.1). Dorsal fin with 25��� 27 branched rays (paratype median = 26, holotype = 26). Anal fin with 31���35 branched rays (paratype median = 33, holotype = 34). Scales cover the body, except for the head. Lateral line visible and complete with 38���40 pored scales along its length. Caudal peduncle relatively thin (2.1 ��� CPL/CPD ��� 2.3, holotype = 2.2). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation. Knollenorgan electroreceptors on head clustered into three distinct rosettes. Holotype (m) Paratypes (n= 8) Min���Max Mean Std���Dev Min���Max Median Meristic counts: Number of scale rows between the anterior base of 14 13���15 14 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 21 15���21 18 Number of teeth in the lower jaw (TLJ) 29 24���30 28 Live coloration (Fig. 11 A). Body and head mostly whitish-silvery, but head also exhibits faint metallic blue-purple iridescence. Dorsum darker than the rest of the body. Melanin patterning consists of two distinct black marks: (1) a distinct ovoid melanin mark below the anterior base of the dorsal fin on each side of the body and (2) a crescent-like melanin mark, sometimes diffuse, centered at the base of the caudal fin on each side and extending onto the upper and lower parts of the caudal fin. No black mark is present at the base of the pectoral fins. The fins themselves are mostly translucent, with the dorsal and caudal fins sometimes turning slightly yellow after formaldehyde preservation. Distribution (Fig. 1). Endemic to the Congo River basin. We collected P. pulsivertens n. sp. along the main course of the L��koli River. This species seemed to be absent from the small tributary creeks flowing through forest or savannah when we surveyed Odzala National Park. Elsewhere, P. pulsivertens n. sp. occurs in the vicinities of Brazzaville (i.e., the Pool Malebo), the Dja River (Cameroon) and the Dzangha-Sangha region (Sangha River basin, Central African Republic) (pers. obs.), although no EOD recordings have been made of this species outside Odzala. Electric organ discharge (Fig. 11 C). The EOD waveform of P. pulsivertens n. sp., which is known only from our recordings in Odzala, resembles an inverted-polarity version of the "typical" Petrocephalus EOD. That is, the temporal sequence of electrocyte face firing known for all other Petrocephalus (i.e., firing of the posterior electrocyte face preceding firing of the anterior electrocyte face) appears to be reversed in P. pulsivertens. At high gain, however, one can see that the very first event in the EOD is a minute head-positive deflection (for an example see Fig. 3 D of Lavou�� et al., 2008). This waveform feature is consistent with current from the stalks of the posterior electrocyte face (and possibly early current during the beginning of posterior face firing itself) slightly preceding anterior face firing. Despite the waveform inversion, histological examination of electrocytes of P. pulsivertens n. sp. reveals them to be type "NPp," the character state also shared by all other Petrocephalus species investigated to date. We suspect that part of the mechanism underlying the reversed ordering of major peaks in the EOD of P. pulsivertens n. sp. might involve changes in firing threshold for one or both electrocyte faces (as proposed in Lavou�� et al., 2008). This interesting example of waveform inversion in Petrocephalus reminds us that careful attention must be paid to the geometry of electrodes during EOD recordings from unknown mormyrid faunas. Given its inverted-polarity appearance, the EOD of P. pulsivertens n. sp. is immediately recognizable as distinct from those of all other congeners. Based on a threshold of 1.5 % of peak-peak amplitude (and at ambient recording temperatures), the duration of the EOD of P. pulsivertens n. sp. ranges from 0.270 to 0.418 msec, falling in the range of many "typical" Petrocephalus EODs. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008). Etymology. From the Latin " pulsus," impulse, beating; and from " vertere, " to turn, exchange. The name describes the unusual EOD waveform of P. pulsivertens n. sp. The inverted appearance of this species��� EOD is unique among all Petrocephalus recorded to date., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 32-35, DOI: 10.5281/zenodo.197589, {"references":["Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus balayi Sauvage, 1883 Mormyrus catostoma ��� G��nther (1867): 116 (non Mormyrus catostoma G��nther, 1866). Petrocephalus balayi Sauvage (1883): 159. Mormyrus ballayi ��� Sauvage (1884): 195. Petrocephalus ballayi ��� Pellegrin (1908): 185. - Boulenger (1909 ���1916): 52. - Gosse (1984): 108. Mormyrus amblystoma G��nther (1896): 281. - Boulenger (1909 ���1916): 52. [Odzala field identification: Petrocephalus sp. 4, OTU 4] Images. Fig. 6 A, photo of a live specimen from Odzala, Fig. 6 B, photo of a preserved specimen from Odzala and Fig. 14, drawing of the holotype of Mormyrus amblystoma from Boulenger (1909 ���1916). Photos of the preserved holotype of Petrocephalus balayi in Lavou�� et al (2004) and Harder (2000). Type material. Holotype, MNHN A 6297, sex undet., 85.5 mm SL. Gabon, Ogoou�� River, without more precision, Expedition Savorgnan de Brazza, No��l Ballay coll. Other specimens. We examined two other specimens from Odzala National Park (see specimen list provided in the section "additional material examined"). We also examined other specimens from the Lower Guinea province [listed in Lavou�� et al. (2004)]. Diagnosis. The following diagnosis is based on all examined specimens of P. balayi, regardless their geographic origins. Petrocephalus balayi is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with 20���22 branched rays. Anal fin with 26 or 27 branched rays. Eye small (4.5 ��� HL/ED, range = 4.5���4.9). Mouth very wide (HL/MW ��� 3.9, range = 2.7���3.9), associated with a very characteristic head shape when viewed from below. Fourteen teeth or more in the upper jaw (range = 14���21). Twenty-eight teeth or more in the lower jaw (range = 28���38). Melanin pattern consisting of the following: (1) a distinct black round mark on each side of the body below dorsal fin origin; (2) an ovoid mark on each side at the base of the caudal peduncle, not extending onto the upper and lower parts of the caudal fin; (3) a black mark, sometimes diffuse but always present, at the base of the pectoral fins. The EOD is of normal polarity. Description. Table 4 presents morphometric ratios and meristic data for the holotype (from the Ogoou�� River in Gabon) and for non-type specimens (from Gabon or Odzala) separately. Data given in the following description (e.g., ranges) correspond to the two Odzala specimens we examined, except where explicit reference is made to the holotype. Petrocephalus balayi, described by Sauvage (1883), is a large, robust species within the genus Petrocephalus (maximum SL observed in Odzala = 95.6 mm SL, holotype = 85.5 mm SL). Body ovoid, longer than high (SL /H = 2.5���2.7, holotype = 2.8) and laterally compressed. Head length between 3.3 and 3.4 times (holotype = 3.3) in standard length. Head width 1.9 times (holotype = 2.2) in head length. Snout short (8.4 ��� HL/SNL ��� 9.3, holotype = 8.1), wide and square-shaped. Mouth wide (2.7 ��� HL/MW ��� 3.1, holotype = 3.4), sub-terminal, opening under the anterior half of the eye. Teeth small and bicuspid, 30 in a single row in the lower jaw and 20���21 in the upper jaw. Eye small (4.5 ��� HL/ED ��� 4.8, holotype = 4.6). Dorsal and anal fins originate in the posterior half of the body (SL / PDD = 1.6 and SL /PAD = 1.6), with pre-dorsal distance equal to pre-anal distance. Pre-dorsal distance slightly exceeds pre-anal distance in the holotype (1.0 ��� PDD /PAD ��� 1.1). Dorsal fin with 22 branched rays (holotype = 21). Anal fin with 27 branched rays (holotype = 26). Scales cover the entire body, except for the head. Lateral line visible and complete with 36 pored scales. Caudal peduncle relatively thick (1.7 ��� CPL/CPD ��� 1.8, holotype = 2.3). Twelve circumpeduncular scales. Skin on head thick, becoming opaque with formalin fixation. Knollenorgans organized into the three rosettes named by Harder (1968). Holotype Specimens from Specimens from (o)* Odzala (n= 2) Gabon (Ogoou�� basin) (n= 7)* Min���Max Min���Max Mean Std���Dev Live coloration (Fig. 6 A). Body gray/silver, slightly darker dorsally. The head is also slightly darker than the rest of the body. Iridescent pigment along side of body sometimes visible with correct orientation of light. Pigmentation pattern with three black patches: (1) a distinct round black mark on each side of the body below the dorsal fin origin; (2) an ovoid black mark on each side at the base of the caudal peduncle that does not extend onto the upper and lower parts of the caudal fin; (3) a black mark, sometimes diffuse in larger individuals but always present, at the base of the pectoral fins. The fins themselves are translucent. Distribution (Fig. 1). Petrocephalus balayi occurs in the southern part of the Lower Guinea province and in the Congo River basin, including Odzala and the Lower Congo River (David & Poll, 1937; Lavou�� et al., 2004; Poll, 1939; Sauvage, 1883). In Odzala, Petrocephalus balayi seems to prefer the small tributary creeks flowing through forest. In Gabon (Lower Guinea province), P. b a l a y i occurs in the lower courses of the Ogoou�� River and numerous associated lakes (and their tributary streams), as well as in small coastal creeks from south of the Ogoou�� to the Congo River basin. Records from the upper part of the Lower Guinea province and elsewhere appear to be misidentifications (pers. obs.). Electric organ discharge (Fig. 6 C). EOD recordings are only available for a small number of individuals: one specimen from the coastal river Doumvou at Doumvou, Gabon [03.33S ��� 10.73 E] (S. Lavou�� & V. Mamonekene coll., 24 July 2001) (Lavou�� et al., 2004); and two specimens from Odzala National Park, Republic of the Congo (Lavou�� et al., 2008). Among these few recordings, the overall waveform of EODs produced by P. b a l a y i seems to be typical for the genus, similar to those produced by several other Petrocephalus species. EOD duration = 0.324 ��� 0.340 msec. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008), who confirmed histologically that electrocytes in P. balayi are of type NPp. Remarks. Almost all measurements and meristic counts of Odzala specimens fall within the range of values defined by the holotype and other specimens from Gabon. The EOD waveforms of the Odzala specimens and those from Gabon are similar (Lavou�� et al., 2004)., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 16-19, DOI: 10.5281/zenodo.197589, {"references":["Sauvage, H. E. (1883) Descriptions de quelques poissons de la collection du Museum d'Histoire Naturelle. Bulletin de la Societe Philomatique de Paris, 7, 156 - 161.","Gunther, A. (1867) New fishes from the Gaboon and Gold Coast. Annals and Magazine of Natural History, 20, 110 - 117.","Gunther, A. (1866) Catalogue of the Fishes in the British Museum, volume 6. London, 368 pp.","Sauvage, H. E. (1884) Note sur des poissons de Franceville, Haut Ogooue. Bulletin de la Societe Zoologique de France, 9, 193 - 198.","Pellegrin, J. (1908) Sur une seconde collection de poissons recueillis par M. E. Haug a Ngomo. Bulletin de la Societe Philomatique de Paris, 11, 184 - 190.","Boulenger, G. A. (1909 - 1916) Catalogue of the Freshwater Fishes of Africa in the British Museum (Natural History). Wheldon and Wesley, London, 4 volumes.","Gunther, A. (1896) Report of a collection of reptiles and fishes made by Miss M. H. Kingsley during her travels in the Ogowe River and in Old Calabar. Annals and Magazine of Natural History, 6, 261 - 285.","Lavoue, S., Hopkins, C. D. & Kamdem Toham, A. (2004) The Petrocephalus (Pisces, Osteoglossomorpha, Mormyridae) of Gabon, Central Africa, with the description of a new species. Zoosystema, 26, 511 - 535.","Harder, W. (2000) Mormyridae and other Osteoglossomorpha. World Biodiversity database, CD - ROM series, ETI BioInformatics, Amsterdam.","Harder, W. (1968) Zum Aufbau der epidermalen Sinnesorgane der Mormyridae (Mormyriformes, Teleostei). Zeitschrift fur Zellforschung, 89, 212 - 224.","David, L. & Poll, M. (1937) Contribution a la faune ichthyologique du Congo belge. Annales du Musee du Congo, Zoologie, 3, 189 - 294.","Poll, M. (1939) Les poissons du Stanley Pool. Annales du Musee du Congo, Zoologie, 4, 1 - 60.","Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339."]}

Petrocephalus odzalaensis n. sp. [Odzala field identification and in Lavoué et al. (2008): Petrocephalus sp. 6, OTU 6] Images. Fig. 8 A, photo of a live specimen from Odzala and Fig. 8 B, photo of the preserved holotype (CU 88048). Type material. Holotype, CU 88048 (morpho, EOD), sex undet., 92.9 mm SL. Republic of the Congo, Lékénie River at Mboko débarcadère (Congo basin), Odzala National Park, (0.62 ° N, 14.90 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. Paratypes. CU 87850 (morpho, EOD), male, 90.1 mm SL; CU 87857 (morpho, EOD), male, 92.6 mm SL; CU 88050 (morpho, EOD), male, 90.4 mm SL; AMNH 251414 (ex CU 87843) (morpho, EOD), male, 87.0 mm SL; AMNH 251417 (ex CU 88056) (morpho, EOD), male, 87.6 mm SL; AMNH 251416 (ex CU 88054) (morpho, EOD), male, 97.6 mm SL; CU 88059 (morpho, EOD), male, 99.3 mm SL; AMNH 251415 (ex CU 87844) (morpho, EOD), male, 87.3 mm SL. Republic of the Congo, Lékénie River at Mboko débarcadère (Congo basin), Odzala National Park, (0.62 ° N, 14.90 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., August 2002. CU 88049 (morpho, EOD; caudal peduncle dissected by Lavoué et al. (2008) to sample electric organ for histological examination), male, 93.2 mm SL. Republic of the Congo, Lékénie River at Mboko débarcadère (Congo basin), Odzala National Park, (0.62 ° N, 14.90 ° E), J.P. Friel, S. Lavoué & J.P. Sullivan coll., 12 August 2002. Holotype (o) Paratypes (n= 9) Min–Max Mean Std–Dev Min–Max Median Meristic counts: Dorsal fin branched rays (DR) 22 20–22 21 Anal fin branched rays (AR) 29 27–29 28 Number of scales in the lateral line (SLL) 38 36–38 37 Number of scale rows between the anterior base of 11 10–14 12 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 11 8–12 11 Number of teeth in the lower jaw (TLJ) 18 18–23 20 Other specimens. We examined 19 other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus odzalaensis n. sp. is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin shorter than anal fin. Dorsal fin with a maximum of 22 branched rays (range = 20–22). Anal fin with a minimum of 27 branched rays (range = 27–29). Mouth sub-terminal; ratio between head length and mouth position is between 4.2 and 5.0. Eye small (3.7 ≤ HL/ED ≤ 4.2). Body pinkish-gray, darker dorsally, with the presence of three distinct pigmentation patches: (1) a distinct ovoid black mark situated below the anterior base of the dorsal fin on each side of the body; (2) a small black mark at the base of each pectoral fin; (3) an ovoid black mark on each side that is centered at the base of the caudal fin, not extending onto the upper and lower lobes of this fin. EOD of normal polarity, appearing triphasic at low gain, with two main phases and a small third phase. A final, fourth phase may be present, but it is always extremely small ( Description. Morphometric ratios and meristic data for the holotype and paratypes are presented in Table 6. Petrocephalus odzalaensis n. sp. is a medium sized species within the genus (maximum SL observed = 99.3 mm; holotype = 92.9 mm). Body ovoid, longer than high (2.6 ≤ SL /H ≤ 2.9, paratype average = 2.8, holotype = 2.6) and laterally compressed. Head length between 3.7 and 4.0 times in standard length (paratype average = 3.9, holotype = 4.0). Snout short (6.2 ≤ HL/SNL ≤ 8.3, paratype average = 7.3, holotype = 6.6) and round. Mouth small (4.0 ≤ HL/MW ≤ 4.8, paratype average = 4.3, holotype = 4.3), sub-terminal, opening just under the anterior half of the eye. Teeth small and bicuspid, 8–12 in a single row in the upper jaw (paratype median = 11, holotype = 11), 18–23 in a single row in the lower jaw (paratype median = 20, holotype = 18). Dorsal and anal fins originate in the posterior half of the body (1.5 ≤ SL / PDD ≤ 1.6 and 1.6 ≤ SL /PAD ≤ 1.7, respectively). Pre-dorsal distance slightly greater than the pre–anal distance (1.0 ≤ PDD /PAD ≤ 1.1). Dorsal fin with 20–22 branched rays (paratype median = 21, holotype = 22). Anal fin with 27–29 branched rays (paratype median = 28, holotype = 29). Scales cover the body, except for the head. Lateral line visible and complete with 36–38 (holotype = 38) pored scales along its length. Ten to 14 scales (paratype average = 12, holotype = 11) between the anterior base of the anal fin and the lateral line. Caudal peduncle thin (1.9 ≤ CPL/ CPD ≤ 2.3, paratype average = 2.1, holotype = 2.1). Twelve scales around the caudal peduncle. Skin on head thick, turning opaque with formalin fixation. Knollenorgans clustered into the three distinct "rosettes" of Harder (1968). Live coloration (Fig. 8 A). Body background color pinkish-gray, darker dorsally. Pigmentation pattern consisting of three characteristic black patches: (1) a distinct ovoid black mark below the anterior base of the dorsal fin; (2) a small black mark at the base of the pectoral fin; and (3) an ovoid black mark centered at the base of the caudal fin, which does not extend onto the upper and lower lobes. Fins translucent. Distribution (Fig. 1). Endemic to the Congo basin. Abundant in Odzala. We collected P. odzalaensis n. sp. at several localities along the main course of the Lékoli River and in some small tributary creeks flowing through forest. Electric organ discharge (Fig. 8 C). The EOD waveform is typical for the genus, similar to EODs produced by many other Petrocephalus species. Total EOD duration ranges from 0.231 to 0.339 msec, based on 1.5 % voltage deviations from baseline relative to peak-peak amplitude. No EOD sex differences are apparent in the specimens recorded thus far. Lavoué et al. (2008) provide additional statistics for waveform landmarks and other EOD measurements. Histological examination confirms that electrocytes are type NPp (Lavoué et al., 2008). Remarks. Based on museum records from the Congo basin (pers. obs.), Petrocephalus odzalaensis has been misidentified as Petrocephalus simus in several instances. The latter species is endemic to the Lower Guinea province (Lavoué et al., 2004). Etymology. Named for Odzala National Park.

Petrocephalus zakoni n. sp. [Odzala field identification and in Lavou�� et al. (2008): Petrocephalus sp. 2, OTU 2] Images. Fig. 4 A, photo of a live specimen from Odzala and Fig. 4 B, photo of the preserved holotype (CU 88101). Type material. Holotype, CU 88101 (morpho, EOD), male, 86.0 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park, (0.62 �� N, 14.95 �� E). J.P. Friel, S. Lavou�� & J.P. Sullivan coll., 20 August 2002. Paratypes. CU 88036 (morpho, EOD), sex undet., 81.4 mm SL; CU 88042 (morpho, EOD), male, 78.6 mm SL; CU 88037 (morpho, EOD), sex undet., 79.6 mm SL; CU 88077 (morpho), male, 84.8 mm SL. Republic of the Congo, Pandaka River (Congo basin), Odzala National Park, (0.62 �� N, 14.92 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. CU 88104 (morpho, EOD), sex undet., 83.5 mm SL; AMNH 251426 (ex CU 88100) (morpho, EOD), male, 73.7 mm SL; AMNH 251427 (ex CU 88103) (morpho, EOD), sex undet., 77.2 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park (0.62 �� N, 14.95 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. CU 88093 (morpho, EOD), male, 67.4 mm SL; AMNH 251424 (ex CU 88088) (morpho, EOD), sex undet., 75.8 mm SL; AMNH 251425 (ex CU 88090) (morpho, EOD), male, 76.0 mm SL. Republic of the Congo, small channel around island in L��koli River (Congo basin), Odzala National Park (0.62 �� N, 14.92 �� E), J.P. Friel, S. Lavou�� & J.P. Sullivan coll., August 2002. Other specimens. We examined 34 other specimens from Odzala National Park (specimen list provided in the section "additional material examined"). Diagnosis. Petrocephalus zakoni n. sp. is distinguished from all other Petrocephalus species in Central Africa (Lower Guinea and Congo provinces) by the following combination of characteristics. Dorsal fin with 23 or 24 branched rays. Anal fin with 27 or 28 branched rays. Eye large (HL/ED ��� 3.3, range = 3.1���3.3). Mouth small (4.4 ��� HL/MW, range = 4.4 ���5.0). Ten teeth or fewer (range = 6���10) in the upper jaw. Twentytwo teeth or fewer (range = 18���22) in the lower jaw. Unique pigmentation pattern consisting of three well defined black patches (Fig. 4 A): (1) an intense dark mark on each side of the body close to the anterior base of the dorsal fin, often extending onto the first dorsal rays, forming a characteristic saddle across the dorsum; (2) a mark on each side of the body at the base of the pectoral fin; (3) a crescent-shaped mark on each side of the body centered at the base of the caudal fin, extending onto the upper and lower parts of the caudal fin. EOD of normal polarity (i.e., first major phase head-positive). Description. Morphometric ratios and meristic data are given in Table 2 for the holotype and paratypes separately. Petrocephalus zakoni n. sp. is a small sized species within the genus (maximum SL in the type series = 86.0 mm, maximum SL observed in all specimens = 90 mm). Body ovoid, longer than high (2.5 ��� SL / H ��� 2.8, paratype average = 2.6, holotype = 2.8) and laterally compressed. Head length between 3.4 and 3.7 times in standard length (paratype average = 3.6, holotype = 3.6). Eye large compared to many Petrocephalus species (3.1 ��� HL/ED ��� 3.3, paratype average = 3.2, holotype = 3.2). Snout short (6.1 ��� HL/SNL ��� 8.5, paratype average = 7.2, holotype = 6.2) and round. Mouth small (4.4 ��� HL/MW ��� 5.0, paratype average = 4.7, holotype = 4.5) and sub-terminal, opening under the posterior half of the eye. Teeth small and bicuspid, 6���10 (paratype median = 8, holotype = 9) in a single row in the upper jaw, 18���22 (paratype median = 19, holotype = 20) in the lower jaw. Dorsal and anal fins originate in the posterior half of the body (1.6 ��� SL / PDD ��� 1.7, paratype average and holotype = 1.6; 1.6 ��� SL /PAD ��� 1.7, paratype average and holotype = 1.6). Pre-dorsal distance roughly equal to the pre-anal distance. Dorsal fin with 23 or 24 branched rays (median = 23, holotype = 24). Anal fin with 27 or 28 branched rays (median = 27, holotype = 28). Scales cover the body, except for the head. Lateral line visible and complete with 36���38 pored scales along its length (paratype average = 37, holotype = 38). Twelve to 14 scales (paratype average = 13, holotype = 14) between the anterior base of the anal fin and the lateral line. Caudal peduncle thin (1.9 ��� CPL/CPD ��� 2.3, paratype average = 2.1, holotype = 2.2). Twelve scales around the caudal peduncle. Skin on head thick, becoming opaque with formalin fixation. Knollenorgans on the head are not clustered into "rosettes" but, instead, appear as isolated receptor pores, the character state observed in the Mormyrinae. Live coloration (Fig. 4 A). Body uniformly white-silver, with the presence of three characteristic pigmentation marks: (1) a very distinctive black mark just below the anterior base of the dorsal fin on each side, often extending onto the first dorsal rays and making contact over the dorsum with the contralateral mark; (2) a blackish mark, sometimes weak but always visible, at the base of the pectoral fins; (3) a crescentshaped black mark centered at the base of the caudal fin on each side, extending onto the upper and lower parts of the caudal fin. Fins otherwise translucent. Distribution (Fig. 1). Apparently endemic to the Congo basin. Abundant in Odzala. We collected P. zakoni n. sp. at several localities along the main channel of the L��koli River at night. Elsewhere in the Congo basin, we have identified specimens of P. z a k o n i n. sp. from the Lower Congo (Pool Malebo) and from the Sangha River basin (unpublished observations). Electric organ discharge (Fig. 4 C). EOD waveforms produced by P. zakoni n. sp. are of relatively short duration among Petrocephalus (range = 0.164���0.281 msec), but they are, nevertheless, very similar in waveform to the EODs of several other Petrocephalus species. EOD sex differences are not apparent in the Odzala population. Statistics for waveform landmarks and other EOD measurements are provided by Lavou�� et al. (2008). Electrocytes are assumed to be of type NPp based on characteristics of the EOD, although electrocyte anatomy has not yet been confirmed histologically. Remarks. Given our identification of specimens from the Lower Congo River and the Dzangha-Sangha Reserve (Sangha River), Petrocephalus zakoni n. sp. is likely a common species in the Congo basin. This species has been previously misidentified as Petrocephalus christyi Boulenger, 1920 because its body proportions are similar to those of P. christyi. In addition, both species exhibit an intense sub-dorsal melanin marking on the flank. Nevertheless, these species can be distinguished by the presence of a black spot at the base of the pectoral fins in P. zakoni n. sp. (absent in P. christyi), the shape of the sub-dorsal marking (ovoid to saddle-shaped versus rounded in P. christyi), the waveshape of the EOD (with two main phases and a weak third phase in P. zakoni versus four phases in P. christyi) and presence/absence of Knollenorgan rosettes on the head (absent in P. zakoni versus present in P. christyi). Holotype (m) Paratypes (n= 10) Min���Max Mean Std���Dev Min���Max Median Meristic counts: Number of scale rows between the anterior base of 14 12���14 13 the anal fin and the lateral line (SDL) Number of teeth in the upper jaw (TUJ) 9 6���10 8 Number of teeth in the lower jaw (TLJ) 20 18���22 19 Etymology. Named in honor of Harold H. Zakon. In addition to Professor Zakon���s many contributions to neuroethology, we recognize the significance of his recent work (Zakon et al., 2006), which inspires a new area of research on genes that underlie electrolocation and electrical communication in gymnotiform and mormyroid fishes., Published as part of Lavou��, S��bastien, Sullivan, John P. & Arnegard, Matthew E., 2010, African weakly electric fishes of the genus Petrocephalus (Osteoglossomorpha: Mormyridae) of Odzala National Park, Republic of the Congo (L��koli River, Congo River basin) with description of five new species, pp. 1-52 in Zootaxa 2600 on pages 9-12, DOI: 10.5281/zenodo.197589, {"references":["Lavoue, S., Arnegard, M. E., Sullivan, J. P. & Hopkins, C. D. (2008) Petrocephalus of Odzala offer insights into evolutionary patterns of signal diversification in the Mormyridae, a family of weakly electrogenic fishes from Africa. Journal of Physiology - Paris, 102, 322 - 339.","Boulenger, G. A. (1920) Poissons recueillis au Congo Belge par l'expedition du Dr C. Christy. Materiaux pour la faune du Congo. Annales du Musee du Congo, Zoologie, 2, 1 - 38.","Zakon, H. H., Lu, Y., Zwickl, D. J. & Hillis, D. M. (2006) Sodium channel genes and the evolution of diversity in communication signals of electric fishes: Convergent molecular evolution. Proceedings of the National Academy of Sciences of the United States of America, 103, 3675 - 3680."]}