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Ichthyol. Explor. Freshwaters, Vol. 00, No. 0, pp. 000-000, 4 figs., 1 tabs., Xxxxxxxxx 0000 © 0000 by Verlag Dr. Friedrich Pfeil, München, Germany – ISSN 0936-9902

Apteronotus magoi, a new species of from the Orinoco basin Venezuela (: Apteronotidae)

Carlos David de Santana*, Otto Castillo** & Donald Taphorn**

Apteronotus magoi, new species, is described from Caño Bravo, Río Apure basin, Río Orinoco system, Barinas state, Venezuela. It is diagnosed from all species in Apteronotus by the unique combination of a dark brown to black body with a prominent, broad cream-colored or yellow band on the chin and the dorsal surface of the head; a narrow cream-colored band on the mid-dorsal region of body; and a caudal peduncle with a white background mottled with black or dark brown spots.

Se describe Apteronotus magoi, una especie nueva de pez cuchillo fantasma, para el caño Bravo, una difluencia del río Apure en la cuenca del Orinoco, estado Barinas, Venezuela. Se diferencia de todas las especies del género Apteronotus por la siguiente combinación de caracteres: un cuerpo oscuro, negro o marrón, una banda ancha de color crema o amarillo sobre la barbilla y la superficie dorsal de la cabeza, y una banda más angosta de la misma coloración sobre la porción medio dorsal del cuerpo; el pedúnculo caudal de coloración blanquecina con manchas oscuras irregulares.

Introduction with at least four of these, “Apteronotus” apuren- sis (Albert & Campos-da-Paz, 1998), Apteronotus Sixty-five species of the Gymnotiformes are re- macrostomus, roseni, and Ster- ported from Venezuela, of which 60 are known nachella orinoco, being endemic to this hydro- to inhabit the Río Orinoco basin (Lasso et al., 2004; graphic system. Recent collecting efforts con- Lundberg, 2005; de Santana & Taphorn, 2006). ducted by the second author in Caño Bravo, a The Neotropical family Apteronotidae, the ghost tributary of the Río Apure in Estado Barinas, electric knifefishes, includes 53 valid species yielded a new species belonging to Apteronotus (Albert, 2003; de Santana, 2003; de Santana et al., sensu Albert & Campos-da-Paz (1998). This genus 2004; de Santana & Maldonado-Ocampo, 2005; comprises 15 valid species, A. albifrons, A. brasili- de Santana & Taphorn, 2006), twenty of which ensis, A. caudimaculosus, A. cuchillo, A. cuchillejo, are known to occur in the Río Orinoco basin A. ellisi, A. eschmeyeri, A. jurubidae, A. leptorhyn- (Lasso et al., 2004; de Santana & Taphorn, 2006), chus, A. macrostomus, A. magdalenensis, A. mariae,

* Division of , Smithsonian Institution, National Museum of Natural History, WG-15, MCR 159, Washing- ton, DC 20013-7012, U.S.A. E-mail: [email protected] ** Museo de Ciencias Naturales de Guanare, Universidad Nacional Experimental de Los Llanos Occidentales Ezequieluncorrected Zamora, Guanare, Portuguesa, 3323, Venezuela. proof copy Ichthyol. Explor. Freshwaters, Vol. 00, No. 0 284

A. milesi, A. rostratus, and A. spurrellii inhabiting belonging to Apteronotus sensu stricto see de streams and rivers of South and Central America Santana (2003), de Santana & Maldonado-Ocam- (Albert, 2001, 2003; de Santana, 2003; de Santana po (2004; 2005), de Santana & Crampton (2006) & Crampton, 2006). In this paper we describe a and de Santana et al. (2004). Institutional abbre- new species of ghost knifefish endemic to the Río viations follow Leviton et al. (1985). Water qual- Orinoco basin, Venezuela. ity values are from different days, at the type locality.

Material and methods Apteronotus magoi, new species Measurements were taken as point-to-point lin- (Figs. 1-2) ear distances using a digital caliper with a preci- sion of 0.1 mm following the methods of Mago- Holotype. MCNG 54795, 237 mm TL; Venezuela: Leccia (1994) and Cox-Fernandes (1998). Anal and Barinas: Río Apure drainage, Caño Bravo, 08°00'S caudal-fin ray counts were taken using dissecting 67°59'W; O. Castillo et al., 3 Mar 2001. microscope with transmitted light. Counts of the holotype are given in brackets (when available). Paratypes. MCNG 54112, 3, 135-234 mm TL; Dietary preferences were determined by the MCNG 49291, 1, 190 mm TL; MCNG 49316, 1, visual analysis of stomach contents using a stereo- 240 mm TL; USNM 388024, 142 mm TL; same microscope. For additional examined material data as holotype.

Table 1. Morphometric data of holotype and paratypes of Apteronotus magoi.

holotype paratypes range mean n Total length [mm] 237.0 135.0-240.0 6 Length to end of anal fin [mm] 190.0 110.0-193.0 6 Head length [mm] 29.0 19.1-29.1 5 Tail length [mm] 48.3 24.8-52.7 5 Percents of length to end of anal fin Anal-fin base 67.9 67.0-78.4 69.9 6 Greatest body depth 12.6 7.2-14.7 12.2 6 Distance snout to anus 8.7 7.9-10.6 9.6 6 Head length 15.2 15.0-17.4 16.3 5 Pre anal distance 14.2 13.3-16.7 15.2 6 Pre pectoral distance 15.0 14.8-17.6 16.2 6 Tail length 30.0 25.3-33.5 28.4 5 Percents of head length Snout length 33.6 32.9-36.0 34.2 5 Mouth length 34.8 28.8-37.9 34.0 5 Eye diameter 4.7 5.7-7.0 6.2 5 Interocular width 19.7 17.6-22.4 19.0 5 Postocular distance 60.5 61.1-70.8 65.0 5 Pectoral-fin length 51.4 45.9-53.9 51.0 5 Internarial distance 11.4 9.2-10.8 10.0 5 Posterior naris to eye 5.7 6.1-7.8 7.1 5 Snout to posterior naris 58.6 58.3-88.6 75.8 5 Head depth at nape 68.7 63.0-70.7 66.1 5 Head width 43.9 38.9-42.4 41.2 5 Branchial opening 16.4 15.9-20.0 18.0 5 Percents of tail length uncorrected Tail depth 8.0 7.5-10.3proof 8.8 5 copy de Santana et al.: Apteronotus magoi 285

Fig. 1. Apteronotus magoi, holotype, MCNG 54795, 237 mm TL. Venezuela: Barinas: Caño Bravo. Scale bar 10 mm.

Diagnosis. Apteronotus magoi is diagnosed from all other species of Apteronotus sensu stricto by the following combination of characters: the body is dark brown to black with a prominent cream- colored or yellow broad band on the chin and the anterior, dorsal midline of head, with a narrower band on the dorsal midline of body; and a white caudal peduncle overlain by mottled black or dark brown spots (Figs. 1-2). Although A. magoi resembles A. albifrons from the Río Orinoco basin, the latter has two well-defined light colored bands a on caudal peduncle throughout ontogeny. Aptero- notus magoi has a shallower caudal fin (7.5-10.3 % of caudal length, n = 6) than A. albifrons (18.3-30.4, n = 11, CU 72159, CU 72374).

Description. Head and body shape, and pigmen- tation illustrated in Figures 1 and 2. Morphomet- rics for holotype and paratypes presented in Table 1. Body laterally compressed, greatest body depth located at, or slightly posterior to, ab- b dominal cavity. Dorsal profile of body nearly straight. First anterior perforated scale of lateral Fig. 2. Apteronotus magoi, holotype, MCNG 54795, line located above pectoral-fin origin. 237 mm TL: a, lateral; and b, dorsal views of head. extendinguncorrected posteriorly to base of caudal fin. Scale proof bars 10 mm. copy Ichthyol. Explor. Freshwaters, Vol. 00, No. 0 286

Fig. 3. Map of Río Orinoco drainage and adjoining regions indicating type locality of Apteronotus magoi.

Head laterally compressed, widest at opercu- inserted into narrow mid-dorsal groove almost lar region and deepest at nape. Dorsal profile of extending to, or slightly beyond, vertical through head convex. Dorsal margin of snout convex from posterior terminus of anal fin. Tail compressed vertical through anterior margin of eye to upper and short; ending in small, elongate caudal fin lip. Eye small, located laterally on head, and with 13-15 [15] rays. completely covered by thin membrane. Anterior naris located at end of small tube and close to tip Coloration in alcohol. Body dark brown to black. of snout. Posterior naris ellipsoid, without tube Prominent cream-colored or yellow broad band and positioned closer to anterior margin of eye present on chin and dorsal midline of head, and than to tip of snout. Mouth terminal, rictus pass- a narrow cream-colored or yellow band on mid- ing posterior of vertical through anterior border dorsal region of body. Pectoral fin dark brown. of eye. Branchial opening located slightly ante- Anal fin dark brown anteriorly with 126-131 [129] rior to vertical through pectoral-fin insertion. dark rays. Posterior portion of fin hyaline with Premaxilla with irregular rows of conical teeth. 21-25 [21] unpigmented rays. Base color of caudal Dentary longer than deep with two rows of peduncle white and overlain with mottled black conical teeth. or dark brown spots. Caudal fin dark brown Pectoral fin elongate, with iii, 13 or 14 [iii, 13] anteriorly, and hyaline posteriorly. rays. Anal-fin origin located at, or slightly ante- rior to, vertical through posterior margin of Distribution and habitat. Apteronotus magoi is opercle. Unbranched anal-fin rays 16-18 [17]; only known from the type locality in the Río total anal-fin rays 145-156 [150]. Scales above Apure drainage, at Caño Bravo, Barinas state, lateral line to middorsal line at mid-body 9-13 [10]. Venezuela (Fig. 3), which was collected repeat- Dark perforated scales on lateral line 61-67 [67]. edly during one year. The new species was cap- Origin of dorsal saggital electroreceptive fila- tured with the following species of the Gymnoti- mentuncorrected on posterior one-half of body. Filament formes:proof Apteronotus albifrons copy, “Apteronotus” apur- de Santana et al.: Apteronotus magoi 287

Fig. 4. Type locality of Apteronotus magoi at Caño Bravo, Venezuela. ensis, macrostomus, and Stern- Comparative material. Apteronotus albifrons: all from archorhynchus roseni. The following catfishes were Venezuela: MCNG 2658, 1, 195 mm TL; Amazonas: also found in association with this species hiding Caño Yatuje, Río Orinoco basin. – MCNG 52993, 1, during the day in the piles of logs and branches: 114 mm TL; Amazonas: Río Orinoco basin. – MCNG 30845, 1, 327 mm TL; Anzoategui: Río Orinoco, Laguna Pseudopimelodus raninus, Cetopsis orinoco, Trachelyo- El Venado. – CU 72159, 5, 101-235 mm TL; Apure: Río pterus galeatus, Panaque nigrolineatus, Hypostomus Matiyure, S of village of Achaguas, Río Apure basin. argus, Pterygoplichthys multiradiatus, Hypostomus – CU 72374, 7, 177-308.4 mm TL; Apure: Río Apure, E ammophilus, Lamontichthys llanero, Spatuloricaria of San Fernando bridge. – MCNG 1496, 14, 87-146 mm gymnogaster, and Farlowella mariaelenae. The hab- TL; Apure: El Frio. Río Apure basin. – MCNG 2893, 1, itat was a near shore area full of submerged tree 103 mm TL; Apure: 1.2 km S of Bruzual, Río Apure trunks and branches over a substrate of sand or basin. MCNG 19912, 3, 138-175 mm TL; MCNG 20351, clay covered with leaf litter (Fig. 4). Water depth 3, 137-157 mm TL; MCNG 20359, 1, 134 mm TL; MCNG 20375, 1, 144 mm TL; MCNG 20712, 1, 132 mm TL; ranged from 0.5 to 1.5 m. The white water Río Apure: Río Arauca. – MCNG 39100, 3, 128-203 mm TL; Apure carries a heavy sediment load and had a Apure: Río Manglar, 1 km from Río Apure. – MCNG current velocity of 0.1 m · s–1. During the collecting 52333, 2, 123-174 mm TL; Apure: Caño Maporal. – season, water temperature ranged from 27.5- MCNG 52588, 6, 204-273 mm TL; Apure: Caño Bucural. 29.0 °C, with an average of 28.8 ± 0.4 °C, dissolved – MCNG 51412, 1, 158 mm TL; Apure: Caño Portrerito. oxygen averaged 7.4 ± 1.08 ppm (6.3-9.8), pH – MCNG 3388, 2, 133-154 mm TL; MCNG 4404, 3, 145- averaged 8.3 ± 0.3 (7.8-8.5), total hardness was 222 mm TL; Barinas: 100 m from Puente Bruzual, Río 56.9 ± 12.5 ppm CaCO (range 39.4-71.6), and Sec- Apure basin. – MCNG 10796, 3, 103-160 mm TL; Barinas: 3 Río Apure. – MCNG 21291, 3, 153-233 mm TL; Barinas: chi disc transparency 29 ± 10 cm (range 15-40). Laguna La Pildora, Río Apure basin. – MCNG 21298, Stomach contents of one individual consisted 1, 141 mm TL; Barinas: Río Suripá, Río Apure basin. – of aquatic insects (immature Trichoptera of the MCNG 49283, 3, 117-130 mm TL; MCNG 49315, 1, families Helicopsychidae and Hydroptilidae). 135 mm TL; MCNG 49365, 1, 147 mm TL; MCNG 49404, 1, 145 mm TL; MCNG 49543, 1, 153 mm TL; MCNG Etymology. Named in honor of the late Fran- 51748, 7, 117-182 mm TL; MCNG 51800, 1, 115 mm TL; cisco Mago Leccia, for his enormous contributions Barinas: Caño Bravo, Río Apure basin. – MCNG 52544, to our knowledge of the Gymnotiformes and for 1, 161 mm TL; Barinas: mouth Río Portuguesa. – MCNG 13107, 1, 133 mm TL; MCNG 14486, 1, 162 mm TL; having recognized this species as undescribed. Guárico: Río Apure basin. – MCNG 11086, 2, 118- uncorrected136 mmproof TL; Monagas: Caño Aguacopy Clarita. – MCNG Ichthyol. Explor. Freshwaters, Vol. 00, No. 0 288

11199, 1, 166 mm TL; Monagas: Río Uracoa. – MCNG Lucena & C. A. S. Lucena (eds.), Phylogeny and 15933, 1, 101 mm TL; MCNG 29282, 1, 160 mm TL; classification of Neotropical fishes. Edipucrs, Porto Monagas: Río Yabo. – MCNG 17349, 1, 65 mm TL; Alegre, Brazil. Monagas: Río Tigre. – MCNG 29128, 3, 85-124 mm TL; Cox-Fernandes, C. 1998. Sex-related morphological Monagas: Río Guanipa, Río Apure basin. – MCNG 1180, variation in two species of apteronotid fishes (Gym- 1, 118 mm TL; MCNG 6168, 3, 117-130 mm TL; MCNG notiformes) from the Amazon River basin. Copeia, 11885, 1, 120 mm TL; MCNG 35748, 3, 26-212 mm TL; 1998: 730-735. Portuguesa: Caño Maraca, Rio Apure basin. Lasso, C., D. Lew, D. Taphorn, C. DoNascimento, O. A. cf. albifrons: MCNG 38192, 1, 130 mm TL; Ven- Lasso-Acalá, F. Pronvenzano & A. Machado-Alison. ezuela: Amazonas: Río Manipitare. – MCNG 38288, 1, 2004. Biodiversidad ictiológica continental de Ven- 101 mm TL; Venezuela: Amazonas: Río Emoni. ezuela. Parte I. Lista de especies y distribuición por A. cf. leptorhynchus: all from Venezuela: MCNG cuencas. Memoria de la Fundación La Salle de 41898, 1, 56 mm TL; Barinas: Río La Yuca. – MCNG Ciencias Naturales, 2004: 105-195. 38913, 1, 74 mm TL; MCNG 41846, 1, 63 mm TL; MCNG Leviton, A. E., R. H. Gibbs, E. Heal & C. E. Dawson. 41861, 2, 106-152 mm TL; MCNG 41913, 4, 30-150 mm 1985. Standards in herpetology and ichthyology: TL; MCNG 41921, 2, 67-85 mm TL; Portuguesa: Río Las Part I. Standard symbolic codes for institutional Marías. – MCNG 38566, 1, 150 mm TL; Portuguesa: Río resource collections in herpetology and ichthyology. Morador. Copeia, 1985: 802-832. Lundberg, J. G. 2005. Gymnorhamphichthys bogardusi, a new specis of sand knifefish (Gymnotiformes: Acknowledgments Rhamphichthyidae) from the Río Orinoco, South America. Notulae Naturae, 479: 1-4. Mago-Leccia, F. 1994. Electric fishes of the continental We thank INAPESCA for scientific collecting permits waters of America. Biblioteca de la Academia de and UNELLEZ – Guanare for support of the Col- Ciencias Fisicas, Matematicas y Naturales, Caracas, lection of the Museo de Ciencias Naturales de Guanare. Venezuela, 207pp. We are grateful to R. Alfonso, E. Alfonzo, M. Alfonso de Santana, C. D. 2003. Apteronotus caudimaculosus n. and A. Alfonso for field assistance, and to the “Inven- sp. (Gymnotiformes: Apteronotidae), a sexually tario de la ictiofauna del Caño Bravo” team A. Cortés, dimorphic from the Pantanal, J. Manduca, J. Escalona, C. Montaña and N. Milani. We western Brazil, with a note on the monophyly of thank J. Maldonado-Ocampo, M. Kottelat, R. Vari and the A. albifrons species complex. Zootaxa, 252: 1-11. an anonymous reviewer for their criticisms on this de Santana, C. D. & W. G. R. Crampton. 2006. Redescrip- paper. CDS is indebted to the Georgia Museum of tion of the ghost knifefish Apteronotus spurrellii from Natural History and the Lakeside Fellowship of the trans-Andean Colombia (Gymnotiformes: Aptero- California Academy of Sciences; to grants offered by notidae). Ichthyological Exploration of Freshwaters, PRONEX/UNISOL/Projeto Piaba/PNOPG (466098/ 17: 115-120. 2001-4 and 550367/2001-2), via L. N. Chao; to an Ernst de Santana, C. D. & J. A. Maldonado-Ocampo. 2004. Mayr Grant of the Museum of Comparative Zoology, Redescription of Apteronotus mariae (Eigenmann & Harvard University; and to a Predoctoral Fellowship Fisher, 1914) and the taxonomic status of Apterono- at the National Museum of Natural History, Smithson- tus jurubidae (Fowler, 1944) (Gymnotiformes: Ap- ian Institution. teronotidae). Zootaxa, 632: 1-14. — 2005. A new species of ghost knifefish (Gymnoti- formes: Apteronotidae) from the Cauca River, with Literature cited a key to apteronotids from the Magdalena-Cauca basin, Colombia. Ichthyological Exploration of Albert, J. S. 2001. Species diversity and phylogenetic Freshwaters, 16: 223-230. systematics of American knifefishes (Gymnoti- de Santana, C. D., J. A. Maldonado-Ocampo, W. Severi formes, Teleostei). Miscellaneous Publications, & G. N. Mendes. 2004. Apteronotus eschmeyeri, a new Museum of Zoology, University of Michigan, 190: species of ghost knifefish from the Magdalena Basin, 1-127. Colombia (Gymnotiformes: Apteronotidae). Zoo- — 2003. Gymnotiformes: Apteronotidae - ghost knife- taxa, 410: 1-11. fishes. Pp. 497-502 in R. E. Reis, S. O. Kullander & de Santana, C. D. & D. C. Taphorn. 2006. Sternarcho- C. J. Ferraris (eds.), Check list of the freshwater rhynchus gnomus, a new species of electric knifefish fishes of South and Central America. Edipucrs, from the Lower Rio Caroni, Venezuela. Ichthyo- Porto Alegre, Brazil. logical Exploration of Freshwaters, 17: 1-8. Albert, J. S. & R. Campos-da-Paz. 1998. Phylogenetic systematics of Gymnotiformes with diagnoses of Received 16 June 2006 58 clades: a review of available data. Pp. 419-446 in Revised 9 October 2006 uncorrectedL. R. Malabarba, R. E. Reis, R. P. Vari, Z. M. S. proof copyAccepted 10 October 2006 de Santana et al.: Apteronotus magoi