Lebiasina yepezi , a new Lebiasininae ( Characiformes : Lebiasinidae ) from the Serra Parima-Tapirapecó mountains

Lebiasina yepezi, a new Lebiasininae with a conspicuous color pattern, is described. The new species is endemic of the headwaters of the rio Negro, rio Branco, and rio Orinoco in the Serra Parima-Tapirapecó Mountains, at the border of Brazil and Venezuela. The new species is readily distinguished from all other Lebiasininae by the presence of four black longitudinal stripes on the trunk, and the triangular shaped dorsal surface of the mesethmoid, lacking lateral projections. The unusual color pattern is contrasted with those of other lebiasinin, as well as members of the pyrrhulinin genus Nannostomus. A close relationship between Lebiasina yepezi and the Gran Sabana (Venezuela) species is suggested based in color pattern features. The present contribution corresponds to a further refutation of the type locality of L. intermedia, as suggested on its description, since Lebiasinins, except L. bimaculata, L. boruca, and L. festae, do not occur in low land waters.


Introduction
The Lebiasinidae is a Neotropical characiform family consisting of seven genera distributed in two subfamilies: Lebiasininae (Lebiasina Valenciennes, plus Piabucina Valenciennes), and Pyrrhulininae (Pyrrhulina Valenciennes, Copeina Fowler, Copella Myers and Nannostomus Günther).The monotypic genus Derhamia Géry & Zarske was originally assigned to the Lebiasininae (Géry & Zarske, 2002), but it was not placed in either subfamilies by Weitzman & Weitzman (2003), and it is currently considered an incertae sedis genus in the Lebiasinidae (Nelson, 2006).The species belonging to the family are small-to medium-sized fishes ranging from the miniature Nannostomus anduzei Fernandez & Weitzman, about 1.6 mm SL, to species of Lebiasina, that reach up to 200.0 -250.0 mm SL.
The greatest diversity of the family occurs in the Pyrrhulininae, which are distributed primarily in the Amazon and Orinoco basins, and coastal rivers of the Guyana Shield, occuring mainly in shallow waters of forest streams and small ponds along the lower parts of larger rivers.Pyrrhulina, the most widespread and speciose genus in the family, is the only one known for the Paraná-Paraguay system (including the rio Uruguay).Species of Lebiasininae, on the other hand, are usually found in the upper courses of streams with rocky or sandy bottoms and well oxygenated high waters in the rio Amazonas, rio Orinoco and coastal drainages on the Atlantic and Pacific slopes of Colombia, Costa Rica, Ecuador, Guyana, Panama, Peru, and Venezuela.The only exception would be Lebiasina intermedia Meinken, presumably from Santarém in the lower Amazon (Géry, 1977;Weitzman & Weitzman, 2003).

Material and Methods
Counts and measurements follow Fink & Weitzman (1974) and Menezes & Weitzman (1990).All measurements were made point-to-point on the left side of the specimens whenever possible, with dial calipers with a precision of 0.1 mm.Standard length is presented in mm, all other measurements are presented as proportions of standard length (SL), except for subunits of head, which are presented as proportions of head length (HL).Meristic data are given in the description, followed by the frequency of each count in parenthesis, and an asterisk indicates the value of the holotype.Counts of teeth, vertebrae, supraneurals, and procurrent caudal-fin rays were taken only from cleared and double-stained paratypes (c&s), prepared according to Taylor & van Dyke (1985), or xrayed specimens.Vertebrae of the Weberian apparatus were included as four elements in the precaudal counts, and the fused PU1+U1 of the caudal region as a single element in the caudal counts.Pattern of circuli and radii was observed on scales sampled from the region between the lateral line series and the insertion of the dorsal fin.Color pattern nomenclature follows Weitzman (1966)

Lebiasina yepezi, new species
Fig. 1 Nannostomus or Pyrrhulina.-Géry, 1977: 588 [photography]  Description.Morphometric data of Lebiasina yepezi are presented in Table 1.Body compressed and elongate.Dorsal profile of body distinctly convex from upper lip to vertical through nares, becoming slightly convex from that point to vertical through pectoral-fin origin, then nearly straight from latter to dorsal-fin origin; and slightly concave from that point to dorsal caudal-fin procurrent rays.Ventral profile of head and trunk convex from lower lip to pelvic-fin origin; straight from that point to anal-fin origin, convex at anal fin base, and concave from anal fin terminus to caudal-fin procurrent rays.Mouth terminal.Premaxillary with single row of 9(1) or 11 (1) tricuspid teeth decreasing in size posteriorly.Posterior tip of maxillary reaching distinctly beyond vertical through anterior margin of orbit.Maxillary with 5(1) or 7(1) tricuspid teeth.Dentary with two series of teeth.Outer series with 12 (1) or 18 (1) pedunculate tricuspid teeth with central cusp distinctly larger, teeth gradually decreasing in size posteriorly.Inner series with several minute conical teeth extending from the symphysis to coronoid process.Branchiostegal rays 4, 3 articulating with anterior-ceratohyal, and one with posteriorceratohyal.
Trunk dark dorsally, becoming lighter ventrally from third longitudinal series of scales.Abdominal area yellowish, lacking pigmentation between the isthmus and anal-fin origin.Mid-dorsal series with a black longitudinal stripe from back of head to dorsal-fin origin.Humeral blotch inconspicuous, round, overlapped by primary stripe.Four dark longitudinal stripes on the trunk.Primary stripe conspicuous, originating posterior to eye, extending across infraorbitals four and five, opercle and along trunk, to terminate at rear of caudal peduncle.Stripe subdivided starting at vertical through dorsal-fin terminus, into 10-12 small round blotches, overlying scales of fourth longitudinal series.Secondary stripe inconspicuous, extending from supracleithrum to middle rays of upper caudalfin lobe, over second and third longitudinal series of scales.Conspicuous intermediate stripe usually extending from mouth to vertical through anal-fin origin, onto scales of fifth longitudinal series, between primary and tertiary stripes.Tertiary stripe densely pigmented,except at proximal portion of caudal peduncle, extending from pectoral-fin origin to middle portion of caudal-fin lower lobe, onto scales of sixth longitudinal series.Caudal-fin blotch diffuse and rounded in juvenile specimens, located at basal portion of five median caudal-fin rays; caudal-fin blotch inconspicuous or absent in specimens longer than 123.0 mm SL, in which it may be represented by patches of chromatophores.Anterior border of caudal-fin blotch not extending onto caudal peduncle.Pelvic and dorsal fins hyaline, base of pectoral-fin rays densely pigmented, forming a round dark blotch.Anal fin lightly pigmented, grayish, with distal border hyaline.Base of last two anal-fin branched rays densely pigmented, forming an oblong dark blotch.Caudal-fin rays densely pigmented.Sexual Dimorphism.Mature males of Lebiasina yepezi present the most common pattern of sex dimorphism among species of the genus: in which the anal-fin rays and anal-fin base are distinctly longer and thicker than females (Fig. 3); hypertrophy of the inclinator muscles and the spiniform processes in which the muscles attach to the first lepidotrichia; scales of the fifth longitudinal series along the base of the anal fin modified (covered by a thin layer of a spongeous, apparently glandular, tissue); and breeding tubercles present on pectoral-, pelvic-and anal-fins rays, as well as on scales and sides of the head.
Distribution.Specimens of Lebiasina yepezi are known from rio Parima (rio Mucajaí system) and rio Uraricoera in the rio Branco drainage, rio Amazonas system, Roraima State, Brazil, the rio Marari (rio Padauari system) in the rio Negro drainage, rio Amazonas system, Amazonas State, Brazil, and the upper rio Orinoco drainage, upstream of La Esmeralda, Amazonas State, Venezuela (Fig. 4).

Etymology. The specific name honors Agustín Fernández
Yépez, first collector of the new species described herein.
Ecological notes.Lebiasina yepezi inhabits small and shaded forest streams, with fast-flowing clear water and a substrate consisting mainly of rocks and sand.

Discussion
In his study of the fish fauna near the río Yaracuy in Venezuela, Fernández-Yépez (1972: 13) mentions in passing a species yet to be described from the upper course of the Orinoco.Given that author had collected specimens of Lebiasina yepezi in 1951 (MHNLS 797), it is likely that he was referring to this species in his comment.Géry (1977: 588) was the first to depict the new species in a photo by Axelrod of a juvenile specimen collected at the Parima mountains in northern Brazil, which is currently cataloged as USNM 306560.In the occasion, Géry listed it as an unidentified characiform, "possibly near Nannostomus or Pyrrhulina".Subsequently, Géry & Zarske (2002: 44-45) proposed a possible relationship between this species and Derhamia hoffmannorum, based on their conception of the relationships of the lebiasinid genera, but the authors did not provide evidence to such a hypothesis.In two phylogenetic studies based on morphologic data of the family Lebiasinidae, Netto-Ferreira (2006, 2010) refuted this hypothesis, proposing L. yepezi as being more closely related to the Lebiasinins from the Guyana Shield than Derhamia.Such close relationship between Lebiasina yepezi and its congeners from the Gran Sabana, Venezuela, L. taphorni, L. unitaeniata, L. uruyensis, and L. yuruaniensis (fig.4) is supported by: first longitudinal series of scales short, ending near the dorsal-fin terminus; posteriorly displaced caudal blotch, not located on the caudal peduncle; secondary stripe passing onto the scales of the second and third longitudinal rows of scales; and the presence of the intermediate stripe, passing at least onto third infraorbital, usually represented by a horizontally elongate blotch (which in few specimens of L. uruyensis may form an inconspicuous stripe, passing onto the scales of the fifth longitudinal series in a way similar to that in L. yepezi).
The presence of multiple dark longitudinal stripes along the body is an unusual color pattern among the Lebiasininae, albeit common among species of the Pyrrhulininae genus Nannostomus Lebiasina yepezi represents an additional species inhabiting both the rio Negro and rio Orinoco drainages.The continuous discovery of new species restricted to the headwaters of rivers draining from the Guyana Shield (Fernández-Yépez, 1967;Ardila-Rodríguez, 1999, 2000, 2004) suggests that the diversity of the Lebiasininae in that area still needs further investigation.Ongoing revisionary studies conducted by the senior author revealed three new lebiasinins occurring in the headwaters of the rio Mazaruni and the rio Potaro (a drainage exhaustively sampled by Eigenmann in the early 20 th century) in the Guyana Shield.
Additionally, three new species have also been discovered in the headwaters of rio Xingu and rio Tapajós, in the Brazilian Shield, an area where lebiasinins were not expected to occur.The apparent peripheric distribution of these species in the upper portions of the rio Amazonas and the rio Orinoco systems represent further evidence that, with exception of Lebiasina bimaculata, L. boruca, and L. festae, species of Lebiasininae do not inhabit low land waters, living exclusively in fast flowing clear headwaters.Therefore, Meinken's suggestion that the type locality of L. intermedia, "near Santarém" is most likely inaccurate as suggested by Géry (1977) and Weitzman & Weitzman (2003).So far, any recent collection yielded specimens comparable with that described by Meinken, and it is likely that specimens of L. intermedia are still awaiting to be rediscovered in either Guyana or Brazilian Shields.

yuruaniensis
Ardila-Rodríguez) by the secondary stripe extending along scales of second and third longitudinal series (vs.stripe extending along scales of first and second longitudinal series), and caudal-fin blotch restricted to the caudal-fin median rays (vs.anterior margin of candal-fin blotch extending onto caudal peduncle).The new species also differ from its closest geographical relatives, L. yepezi differs from L. taphorni Ardila-Rodríguez, L. unitaeniata (Günther), L. uruyensis, and L. yuruaniensis Ardila-Rodríguez by the extent of the intermediate stripe (from infraorbitals to anal-fin origin; vs. intermediate stripe restricted to infraorbitals 2 to 4).