Verlag Dr. Friedrich Pfeil ISSN 0936-9902 Ichthyological Exploration of Freshwaters An international journal for field-orientated ichthyology Volume 24 Number 4 361 Ichthyol. Explor. Freshwaters, Vol. 24, No. 4, pp. 361-369, 3 figs., 1 tab., April 2014 © 2014 by Verlag Dr. Friedrich Pfeil, München, Germany – ISSN 0936-9902 Nannocharax dageti, a new distichodontid from the Democratic Republic of the Congo and Zambia (Teleostei: Characiformes) Fernando C. Jerep*, **, Richard P. Vari* and Emmanuel Vreven*** Nannocharax dageti, new species, is described from southern tributaries of the Congo River basin in the Demo- cratic Republic of the Congo and Zambia and the Kafue River basin of the Zambezi River catchment in Zambia. The new species is distinguished from its congeners by the pigmentation pattern consisting of vertically elon- gated, dark, rounded blotches overlapping a dark midlateral longitudinal stripe; the separation of the blotches in many cases from the dorsal saddles that extend to the middorsal line; the symmetrical coloration pattern on each caudal-fin lobe consisting of a dark spot on the base of each lobe and a series of dark spots forming a trans- verse narrow stripe across each lobe approximately one-third of the distance from the fin margin; a dorsal-fin origin situated anterior of the pelvic-fin origin; and the possession of 40 to 43 scales along the incompletely pored lateral-line series. Nannocharax dageti is apparently allopatric to other species of Nannocharax in southern tributar- ies of the Congo River. Introduction drainages of West Africa host the highest species- level diversity in Nannocharax (Daget & Gosse, The genus Nannocharax Günther, 1867 consists of 1984; Poll, 1973; Vari, 2007; Jerep & Vari, 2013, small-sized, typically elongate-bodied distich- 2014) with the number of species of the genus odontids inhabiting fast to slow-moving fresh- attenuating away from those areas. water habitats across major portions of Africa In his phylogenetic analysis of the family (Daget, 1961; Vari, 2007; Dunz & Schliewen, 2009; Distichodontidae, Vari (1979) proposed that Nan- Jerep & Vari, 2013). The geographic range of the nocharax and Hemigrammocharax Pellegrin, 1923 genus extends from the Nile River basin in North formed a monophyletic assemblage supported Africa south across the sub-Saharan portions of by a dozen synapomorphies. That author was the continent to the Zambezi and Okavango unable to identify any derived features indicating river basins. The Congo basin and the coastal that each genus was monophyletic and com- * Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20013-7012, USA. E-mail: [email protected]; [email protected] ** Departamento de Biologia Animal e Vegetal, Centro de Ciências Biológicas, Universidade Estadual de Lon- drina, Londrina, PR, 86051-990, Brazil. *** Royal Museum for Central Africa, Vertebrate Section, Ichthyology, Leuvensesteenweg 13, B-3080 Tervuren, Belgium; and Katholieke Universiteit Leuven, Laboratory of Biodiversity and Evolutionary Genomics, Charles de Beriotstraat 32, B-3000 Leuven, Belgium. E-mail: [email protected] Ichthyol. Explor. Freshwaters, Vol. 24, No. 4 362 mented that “the monophyly of each of these particular count is indicated in parentheses, and genera is open to question” (Vari, 1979: 332). the counts for the holotype in square brackets. Various researchers both prior and subsequent Information about dentition, number and shape to that study (Roberts, 1967; Jubb & Gaigher, 1971; of infraorbitals, and number of branchiostegal Vari & Géry, 1981; Coenen & Teugels, 1989; Jerep rays was taken from two cleared and stained & Vari, 2013, 2014) similarly questioned whether specimens prepared according to Taylor & Van the single character used by Pellegrin (1923) to Dyke (1985). Vertebral counts were taken from delimit Hemigrammocharax from Nannocharax (the radiographs and include the four vertebrae of the degree of poring of the lateral line – incomplete Weberian apparatus and the terminal centrum. in Hemigrammocharax versus completely pored in Museum abbreviations are as follows: AMNH, Nannocharax) yielded natural assemblages of spe- American Museum of Natural History, New York; cies. Most recently, Jerep & Vari (2014) demon- ANSP, The Academy of Natural Sciences of strated that loss of complete poring of the lateral Drexel University, Philadelphia; BMNH, Natural line within the N. ocellicauda species complex oc- History Museum, London; CUMV, Cornell Uni- curred independent of the loss of poring else- versity Museum of Vertebrates, Ithaca; FMNH, where in the Hemigrammocharax-Nannocharax Field Museum of Natural History, Chicago; MCZ, lineage defined by Vari (1979). In light of that Museum of Comparative Zoology, Harvard Uni- morphologically based evidence those authors versity, Cambridge; MHNG, Muséum d’Histoire placed Hemigrammocharax as a junior synonym of Naturelle, Genève; MRAC, Musée Royal de Nannocharax. This course of action was also ad- l’Afrique Centrale, Tervuren; NRM, Naturhisto- vocated by Arroyave et al. (2013) based on the riska Riksmuseet, Stockholm; SU, former Stan- results of their molecular analysis of the Dis- ford University collections at California Academy tichodontidae, which incorporated a subset of the of Sciences, San Francisco; USNM, National species in each genus. Under the more encompass- Museum of Natural History, Smithsonian Institu- ing concept of Nannocharax proposed by these tion, Washington; and ZSM, Zoologische Staats- two sets of authors, that genus is diagnosed by sammlung München, München. the twelve synapomorphies of different body systems proposed by Vari (1979: 331) to the Hemigrammocharax-Nannocharax lineage. Ongoing Nannocharax dageti, new species revisionary and phylogenetic studies of Nanno- (Figs. 1-2) charax in this expanded sense revealed an unde- scribed species of the genus from the southern Nannocharax macropterus: Bell-Cross, 1976: 115- tributaries of the Congo River basin in the 116 [listed for upper Zambezi and Kafue river Democratic Republic of the Congo and the Kafue systems; brief description; photographed River system within the Zambezi River drainage specimen]. – Bell-Cross & Minshull, 1988: in Zambia. We herein describe the new species 133-134 [listed for upper Zambezi and Kafue of Nannocharax, thereby increasing the species- river systems; brief description; photographed level diversity of the genus to 40 species. specimen]. – Marshall, 2011: 128 [listed for upper Zambezi and Kafue river systems; brief description; biology; illustration of species]. Material and methods Holotype. MRAC P-88846, holotype, 34.8 mm Measurements were taken point-to-point, when SL; Democratic Republic of the Congo: Kando, possible, on the left side of specimens under a 10°48' S 26°13' E; T. de Caters, Sep-Oct 1953. microscope using a digital caliper to 0.1 mm. Body measurements are presented as percentages of Paratypes. AMNH 261176, 2, 28.4-29.0 mm SL; the standard length (SL), and subunits of the head CUMV 91305, 16, 23.9-34.6 mm SL (5, 27.2- are presented as percentages of the head length 34.6 mm SL); USNM, 427064, 4, 25.3-32.5 mm SL (HL). Measurements and counts follow those (2, c&s, 25.3-27.4 mm SL; out of CUMV 91305); utilized by Vari & Ferraris (2004) and Dunz & Zambia: Northern Province: Chambeshi River Schliewen (2009), with additional modifications drainage, Kanchibiya stream at bridge on Kasama- as detailed in Jerep & Vari (2013). In the descrip- Mpika road; 11°29'44.1" S 31°16'46.5" E; R. Bills, tion, the number of examined specimens with a A. Chilala & J. P. Friel, 13 Oct 2005. – BMNH Jerep et al.: Nannocharax dageti 363 Fig. 1. Nannocharax dageti, MRAC P-88846, holotype, 34.8 mm SL; Democratic Republic of the Congo: Kando. Fig. 2. Nannocharax dageti, CUMV 91303, 34.4 mm SL; Zambia: Northern Province: Samfa rapids at pontoon on Chambeshi River. 1972.8.4.18-32, 11 of 15, 21.8-39.1 mm SL (10 border with Angola; 10°33'09.8" S 22°18'35.7" E; E. measured, 27.1-39.1 mm SL); Zambia; G. Bell- Vreven, U. Schliewen, A. C. Manda, J. M. Kasha- Cross. – CUMV 91303, 5, 30.1-34.4 mm SL, Zam- la, B. K. Manda, E. Abwe, B. Muti, Ibrahim, 24 Jul bia: Northern Province: Chambeshi River drain- 2012. – ZSM 41970, 1, 17.8 mm SL; Democratic age, Samfa Rapids at pontoon on Chambeshi Republic of Congo: Lualaba Province: Mangoa River; 10°51'07.5" S 31°10'02.2" E; R. Bills, Chilala stream, above and below road bridge, tributary & J. P. Friel, 11 Oct 2005. – MRAC P-96083.1136- of Lwahu River, right bank tributary of Kasai 96083.1139, 4, 26.8-29.9 mm SL; Zambia: River, 996 m asl, approximately 6.5 km by air Chambeshi River system, Lukupa River, ap- NNE of Dilolo at border with Angola; 10°38'35.8" S proximately 28 km on road from Kasam to Lu- 22°21'54.9" E; E. Vreven, U. Schliewen, A. C. wimgu; 10°10'49.9" S 30°57'45.4" E; L. de Vos, 20 Manda, J. M. Kashala, B. K. Manda, E. Abwe, B. Oct 1995. – MRAC P-142078–142081, 4, 35.5- Muti, Ibrahim, 27 Jul 2012. 44.2 mm SL; Zambia: Solwezi River, Kafue River system; 12°12' S 26°24' E; G. Bell-Cross, 8 Mar 1963. Diagnosis. Nannocharax dageti is distinguished – MRAC P-144818-144821, 4, 32.2-41.9 mm SL; from all its congeners except N. angolensis, N. gra- Democratic Republic of the Congo: Katanga: cilis, N. lineostriatus, N. luapula, N. macropterus and Kimilolo River, environs of Lubumbashi (for- N. taenia by the body coloration pattern of a series merly Élisabethville); M. Lips, Sep 1962. – MRAC of vertically elongated, rounded blotches that P-144872-144873, 2, 26.6-27.9 mm SL; Demo- overlie a longitudinal midlateral dark stripe but cratic Republic of the Congo: Katanga: environs are largely separate dorsally from the saddles of Lubumbashi (formerly Élisabethville); M. Lips, extending to the dorsal midline.