Identification keys for the fish of continental and insular waters of Costa Rica. Part I: Families

Introducción: El conocimiento sobre la composición taxonómica de la fauna de peces de agua dulce de Costa Rica ha cambiado sustancialmente en las últimas dos décadas. No solamente por la adición de nuevas especies y táxones supra-específicos, sino también por reordenamientos y cambios taxonómicos en los diferentes niveles jerárquicos. Las claves taxonómicas disponibles se publicaron hace más de 20 años y están desactualizadas. Objetivo: Brindar información actualizada, en lenguaje sencillo, para la identificación de todas las familias costarricenses de peces continentales e insulares. Métodos: Utilizamos literatura especializada, colecciones de museos y especímenes recolectados recientemente para actualizar las claves disponibles tomando como referencia una lista de familias del 2013. Resultados: La clave dicotómica ilustrada, que cubre 53 familias, se basa en características externas relativamente fáciles de identificar. También incluimos información sobre la composición de especies, distribución general y uso del hábitat. Conclusión: Esta clave permite la identificación de 274 especies de peces costarricenses a nivel de familia, como base para su identificación a categorías más bajasIntroduction: Knowledge about the taxonomic composition of the Costa Rican freshwater fish fauna has changed substantially in the last two decades. Not only due to the addition of new species and supra-specific taxa, but also due to rearrangements and taxonomic changes at the different hierarchical levels. The available taxonomic keys were published more than 20 years ago and are outdated. Objective: To provide up-to-date information, in a friendly language, for the identification of all Costa Rican families of continental and insular fishes. Methods: We used the literature, museum collections and recently collected specimens to update a 2013 family list. Results: The key covers 53 families. The illustrated dichotomous key is based on external characters that are relatively “easy” to identify. We also include information about species composition, general distribution and habitat use. Conclusion: This key allows the identification of 274 fish species to family level, as a basis for further identification.Universidad de Costa Rica/[808-C1-125]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

A new species of Urobatis (Myliobatiformes: Urotrygonidae) from the tropical Eastern Pacific.

Una nueva especie de raya redonda con espina, Urobatis pardalis sp. nov., es descrita a partir de material recolectado en las costas del Pacífico de Costa Rica. Esta nueva especie difiere de sus congéneres por el patrón de la coloración dorsal del disco y por varias relaciones de medidas. Se presenta una clave para la determinación taxonómica de las especies del género.A new species of round stingray, Urobatis pardalis sp. nov., is described from material collected in the Pacific coast of Costa Rica. This new species differs from its congeners by the color pattern of the dorsal surface and by several proportional measurements. A key to all species of the genus is provided.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Lampriformes

Key to eastern Pacific species of the order Lampriformes <p> The following key is based on our research and data available in the literature (Fitch 1964, Miller & Lea 1972, Hart 1973, Rosenblatt & Butler 1977, Heemstra 1986a, b, c, Heemstra & Kannemeyer 1984, 1986a, b, Hulley 1986, Nakamura et al 1986, Paulin <i>et al.</i> 1989, Pequeño 1991, 2011, Collette 2003, Olney 2003a, b, c, d, e, Craig <i>et al.</i> 2004, Nelson 2006, Ruiz & Gosztonyi 2010, Savinykh & Baitalyuk 2011, Roberts 2012)</p> <p> 1 Body oval; all fins well developed, the caudal fin forked (LAMPRIDAE); body blue (dorsally), purple or pink (ventrally), with prominent pale spots in irregular rows (off California, USA, and Baja California Sur, Mexico; Gulf of California, Mexico; off Peru and Chile)............................................................ <i>Lampris guttatus</i> (Brünnich 1788)</p> <p>- Body elongate, ribbonlike; pelvic and anal fins usually absent or reduced, caudal fin not forked; body color not as described above...............................................................................................2</p> <p> 2 Eyes tubular, directed forward; jaws highly protrusible; lower jaw length about equals to head length (STYLEPHORIDAE) (off California, USA, Baja California and Baja California Sur, Mexico; Gulf of California, Mexico; off Colombia, Ecuador, Peru and Chile)............................................................ <i>Stylephorus chordatus</i> Shaw 1791</p> <p>- Eyes not tubular; jaws more or less protrusible; lower jaw shorter than head length................................. 3</p> <p>3 Upper jaw slightly protrusible; maxilla slender, its width less than 50% the eye diameter; anus located at the posterior end of body; anal fin present (LOPHOTIDAE).................................................................. 4</p> <p>- Upper jaw very protrusible; maxilla width more than 50% the eye diameter; anus located at or near middle of body; anal fin present, rudimentary, or absent.......................................................................... 5</p> <p> 4 Crest on top of head protrudes far forward of the upper jaw; dorsal fin with more than 300 rays (usually 310–392); anal-fin rays 5–9 (off California, USA; Gulf of California, Revillagigedo Islands and central coast of Mexico)............................................................................................. <i>Eumecichthys fiski</i> (Günther 1890)</p> <p> - Crest on top of head extends forward to the tip of the upper jaw; dorsal fin with fewer than 300 rays (usually 210–229); analfin rays 19–21 (off California, USA, and Baja California, Mexico)......... <i>Lophotus capellei</i> Temminck & Schlegel, 1845</p> <p> 5 Anal fin present, rudimentary, with 6–7 rays; caudal fin highly modified and divided in two lobes, upper lobe with four or five short rays, lower lobe with six or seven elongate rays forming a caudal projection that may equal the body length in undamaged specimens (RADIICEPHALIDAE) (off California, USA, and Baja California, Mexico)................................................................................................ <i>Radiicephalus elongatus</i> Osório, 1917</p> <p>- Anal fin absent; caudal fin absent (in large specimens of REGALECIDAE) or, if present (in members of TRACHIPTERIDAE and small specimens of REGALECIDAE), not as described above.............................................. 6</p> <p>6 Body greatly elongated, its depth usually 1–8% SL; dorsal fin with more than 250 rays (usually 320–450), the rays smooth (without minute spines or prickles along their lateral edges); pelvic fin with a single elongate ray (REGALECIDAE)..... 7</p> <p>- Body less elongated, its depth usually 10–40% SL; dorsal fin with less than 250 rays (usually 130–215), the rays with minute spines or prickles along their lateral edges; pelvic fins usually with 5–10 rays, often elongate in juveniles, sometimes lost at metamorphosis (TRACHIPTERIDAE)................................................................... 9</p> <p> 7 Premaxilla extending forward along dorsal profile of head; axis of maxilla oblique; dorsal-fin origin usually located behind middle of eye; first 1–3 dorsal-fin rays elongated, not forming a single or double crest but membranously joined to each other as well as to the other dorsal-fin rays; total gill rakers on first gill arch 6–10 (off Chile)...................................................................................................... <i>Agrostichthys parkeri</i> (Benham 1904)</p> <p>- Premaxilla usually not extending forward along dorsal profile of head; axis of maxilla not oblique; dorsal-fin origin usually located ahead middle of eye; first 4–19 dorsal-fin rays elongated, forming a double crest, the first crest with 3–8 rays membranously joined to each other and the second crest with 1 or 5–11 rays not membranously joined to each other as well as to the other dorsal-fin rays; total gill rakers on first gill arch 33–60................................................... 8</p> <p> 8 Dorsal fin with more than 390 rays (usually 400–450); dorsal-fin rays until the end of the abdomen usually 90–120; first dorsal fin crest with 6–8 rays; second dorsal fin crest with 5–11 rays; total gill rakers on first gill arch usually 33–47, in large fish (off California, USA, and Baja California Sur, Mexico; off Ecuador, Peru and Chile).......... <i>Regalecus glesne</i> Ascanius 1772</p> <p> - Dorsal fin with less than 390 rays (usually 320–370); dorsal-fin rays until end of abdomen usually less than 85; first dorsal fin crest with 3–6 rays; second dorsal fin crest with a single ray; total gill rakers on first gill arch usually 47–60 (from California, USA, to central Mexico)...................................................... <i>Regalecus russelii</i> (Cuvier 1816)</p> <p>9 Ventral portion of tail smooth, not covered by spiny plates or bony tubercles; caudal fin not divided in two lobes and on the horizontal axis of the body, with 4–10 total rays........................................................... 10</p> <p> - Ventral portion of tail covered by spiny plates or bony tubercles; caudal fin divided in two lobes, upper lobe upturned and usually fan-like, usually with 6–12 rays, lower lobe on the horizontal axis of the body or slightly upturned, usually with 1–6 rays (rudimentary spiny nubbins in some <i>Trachipterus</i> and large specimens of <i>Zu</i>)................................... 11</p> <p> 10 Snout length greater than eye diameter; scales present in prejuveniles and small juveniles, absent in adults; precaudal vertebrae 21–25, preanal vertebrae 46–51, total vertebrae 106–110; caudal-fin rays 4–7 (usually 6) (off Oregon and California, USA, Baja California, Baja California Sur and the mouth of the Gulf of California, Mexico; off Peru)......................................................................................... <i>Desmodema lorum</i> Rosenblatt & Butler 1977</p> <p> - Snout length shorter than eye diameter; scales usually absent; precaudal vertebrae 18–20, preanal vertebrae 37–42, total vertebrae 71–74; caudal-fin rays 7–10 (usually 8) (from California, USA, to Chile)...... <i>Desmodema polystictum</i> (Ogilby 1898)</p> <p> 11 Dorsal-fin rays 115–150 (usually less than 145); scales usually present, deciduous, imbricated and cycloids; lateral line runs along ventral edge of tail as a zigzag series of elongate spiny plates; ventral edge of body usually scalloped and without bony tubercles (from California USA, to Chile)............................................ <i>Zu</i> <i>cristatus</i> (Bonelli, 1820)</p> <p>- Dorsal-fin rays 145–185 (usually more than 155); scales usually absent or, if present, modified ctenoids; lateral line usually straight, as a series of oval plates each with a central and well-defined spine (usually in juveniles) or as an almost continuous tube (formed by the fusion of plates) with rudimentary blunt spines (usually in adults), usually well above ventral edge of tail; ventral edge of body usually straight and with bony tubercles................................................. 12</p> <p> 12 Ventral and dorsal body contours converge behind the anus (to within about an eye’s diameter of each other) and continue posteriorly nearly parallel to each other, forming an elongate strap-like tail; precaudal vertebrae usually 25–28, preanal vertebrae usually 39–42, total vertebrae usually 69–72 (from Oregon, USA, to Chile)............. <i>Trachipterus fukuzakii</i> Fitch, 1964</p> <p> - Ventral body contour straight for entire length, dorsal contour descending in a straight line from nuchal crest to caudal fin origin; precaudal vertebrae usually 35–45, preanal vertebrae usually 50–55, total vertebrae usually 90–94 (from Alaska, USA, to Chile).............................................................. <i>Trachipterus trachypterus</i> (Gmelin, 1789)</p>Published as part of <i>Angulo, Arturo & López-Sánchez, Myrna I., 2017, New records of lampriform fishes (Teleostei: Lampriformes) from the Pacific coast of lower Central America, with comments on the diversity, taxonomy and distribution of the Lampriformes in the eastern Pacific Ocean, pp. 573-591 in Zootaxa 4236 (3)</i> on pages 586-587, DOI: 10.11646/zootaxa.4236.3.11, <a href="http://zenodo.org/record/322327">http://zenodo.org/record/322327</a&gt

Trachipterus fukuzakii Fitch 1964

<i>Trachipterus fukuzakii</i> Fitch, 1964 — TRACHIPTERIDAE <p>Tapertail ribbonfish (En); Listoncillo pabilo (Sp) (Figure 3, Tables 1 and 4)</p> <p> <b>Material examined.</b> 1 specimen (UCR 2901-2.001); adult, 1071 mm TL, 1049 mm SL, collected near Golfito, Puntarenas, Costa Rica, eastern Pacific Ocean, 8° 36' 17.25" N, 83° 12' 35.23" W, on 25 October 2010, by Federico Hampl using long line.</p> <p> <b>Diagnostic characters.</b> A member of Trachipteridae in congruence with the diagnostic characters listed for the family in Heemstra & Kannemeyer (1984, 1986b), Olney (2003d) and Nelson (2006). Generic and specific diagnostic characters are listed below, all in accordance with descriptions of specimens by Fitch (1964) and Savinykh & Baitalyuk (2011).</p> <p> Ventral portion of tail covered by spiny plates (vs. smooth, not covered by spiny plates in species of <i>Desmodema</i>); caudal fin divided in two lobes (vs. not divided in two lobes in species of <i>Desmodema</i>); dorsal-fin rays about 160 (vs. 115–150 in species of <i>Zu</i>); lateral line straight, as a series of oval spiny plates (vs. as a zigzag series of elongate spiny plates in species of <i>Zu</i>); ventral edge of body straight (vs. usually scalloped in species of <i>Zu</i>) and with bony tubercles (without bony tubercles in species of <i>Zu</i>); precaudal vertebrae 26 (vs. usually more than 30 in all other known species of <i>Trachipterus</i>), preanal vertebrae 40 (vs. usually more than 45 in all other known species of <i>Trachipterus</i>), total vertebrae 71 (vs. usually more than 80 in all other known species of <i>Trachipterus</i>; Fitch 1964, Heemstra & Kannemeyer 1984, Savinykh & Baitalyuk 2011).</p> <p> <b>Description.</b> Measurements and counts, as well as comparative data, are presented in Table 4. Body elongate, ribbon-like, highly compressed, covered with oval-shaped spiny plates. Dorsal profile sloping down evenly and in a straight line from the forehead, dorsal to the orbit, posteriorly to the caudal region; ventral profile nearly straight (parallel with the body axis) for almost its entire length; posterior to anus, the dorsal and ventral profiles gradually converge forming an elongate and tapered tail whose length correspond to about 33% of SL; ventral contour of body with several rows of stiff, pointed, fleshy papillae which diminish in size caudally. Maximum body depth about one head length anterior to the anus.</p> <p>Head length about 30% of snout-vent length; snout length about 82% of eye diameter; end of maxilla anterior to the center of the orbit. Dorsal-fin origin posterior to the middle of the orbit; first dorsal-fin rays apparently elongated but broken, subsequent rays relatively short, becoming longer toward the center region of the body, with the maximum height of fin anterodorsal to the anus; pectoral fins low; pelvic fins completely reduced to the bases, with no shortened pelvic-fin rays or nubbins; caudal fin divided in two lobes, the upper lobe upturned, with eight rays, the lower lobe, on the horizontal axis of the body, represented by six rudimentary spiny nubbins.</p> <p>inconspicuous) or unavailable are representeđ with an en-đash (Q).</p> <p> <b>Character UCR 2901-2.0 0 1 Fitch (1964) Fitch (1967) Charter & Moser (1996 a) Morphometrics</b></p> <p>Color in live not recorded. Color in alcohol (see Figure 3) brown, with the head, opercular region and tail darker, a small, ovate dark blotch at the dorsal contour under the rays 20–23, and narrow dark streaks on both the dorsal and ventral contours running out the caudal-fin base.</p> <p> <b>Remarks.</b> The species <i>T. altivelis</i> (originally described from the coast of Chile) as diagnosed by Fitch (1964), and according to Hamilton (1915), Palmer (1961) and Heemstra & Kannemeyer (1984), overlaps, in all meristics and most measurements presented, with the descriptions of the species <i>T. trachypterus</i> (originally described from the Mediterranean Sea). Although Fitch (1964) synonymizes <i>T. weychardi</i> Philippi, 1874, <i>T. seleniris</i> Snyder, 1908 and <i>T. rexsalmonorum</i> Jordan & Gilbert, 1894 (the first described from the coast of Chile, the two remaining described from the coast of California, USA) with <i>T. altivelis</i>, the author does not address any relationship with <i>T. trachypterus</i> since the species was not originally described from the eastern Pacific Ocean. Recently, Savinykh & Baitalyuk (2011), in an attempt to clarify the taxonomic status of the genus in the northern Pacific Ocean, based on the examination of several specimens, as well as literature records, conclude that only two species (<i>T. fukuzaki</i> and <i>T. trachypterus</i>) should be considered as valid in the northeastern Pacific Ocean. The authors considered <i>T. altivelis</i> and <i>T. ishikawae</i> Jordan & Snyder, 1901 (a species from the western and central North Pacific Oceans) as junior synonyms of <i>T. trachypterus</i> based on their inability to diagnose such species using meristic characters, in accordance with Hamilton (1915) and Palmer’s (1961) observations. As noted above (and in the key; see below), both species (<i>T. fukuzaki</i> and <i>T. trachypterus</i>) can be clearly separated mainly by the vertebrae number (which is lower in <i>T. fukuzaki</i>).</p> <p> Although <i>T. fukuzakii</i> has a postulated distribution extending from Oregon, USA, to Chile (see Table 1), there are no published records between the Gulf of California, Mexico (Del Moral-Flores <i>et al.</i> 2013) and the Peru-Chile coasts (Pequeño 1989, 2011, Chirichigno & Vélez 1998). Our specimen represents, on the basis of Bussing & López (1994, 2005, 2009, 2011), the first documented record of the species in lower Central American (Costa Rican) Pacific waters.</p>Published as part of <i>Angulo, Arturo & López-Sánchez, Myrna I., 2017, New records of lampriform fishes (Teleostei: Lampriformes) from the Pacific coast of lower Central America, with comments on the diversity, taxonomy and distribution of the Lampriformes in the eastern Pacific Ocean, pp. 573-591 in Zootaxa 4236 (3)</i> on pages 582-584, DOI: 10.11646/zootaxa.4236.3.11, <a href="http://zenodo.org/record/322327">http://zenodo.org/record/322327</a&gt

Regalecus russelii Cuvier 1816

<i>Regalecus russelii</i> (Cuvier 1816) — REGALECIDAE <p>Oarfish (En); Pez remo (Sp)</p> <p>(Figure 2, Tables 1 and 3)</p> <p> <b>Material examined.</b> 1 specimen (UCR 2478.001); adult, 3379 mm TL, 3353 mm SL, collected in the Gulf of Papagayo, Costa Rica, eastern Pacific Ocean, 10° 45' 0" N, 85° 42' 0" W, on 12 September 1995, by Mike Bragg on board of the Don Roberto vessel, found floating on surface.</p> <p> <b>Diagnostic characters.</b> A member of Regalecidae in congruence with the diagnostic characters listed for the family in Heemstra (1986c), Olney (2003e), Nelson (2006) and Roberts (2012). Generic and specific diagnostic characters are listed below, all in accordance with descriptions of specimens by Chávez-Ramos <i>et al.</i> (1985), Castro-Aguirre <i>et al.</i> (1991, as <i>R. kinoi</i>), Salazar-Hermoso <i>et al.</i> (1999), Schmitter-Soto (2008), Ruiz & Gosztonyi (2010) and Roberts (2012).</p> <p> Premaxilla not extending forward along dorsal profile of head (vs. extending forward along dorsal profile of head in <i>Agrostichthys parkeri</i>); axis of maxilla not oblique (vs. oblique in <i>A. parkeri</i>); dorsal-fin origin located ahead middle of eye (vs. behind of middle of eye in <i>A. parkeri</i>); first four dorsal-fin rays forming a double crest (vs. not forming a single or double crest in <i>A. parkeri</i>); total gill rakers on first gill arch 51 (vs. 6–10 in <i>A. parkeri</i> and 33–47 in <i>R. glesne</i>); dorsal-fin rays 323 (vs. more than 390, usually 400–450, in <i>R. glesne</i>); dorsal-fin rays until end of abdomen 77 (vs. 90–120 in <i>R. glesne</i>); first dorsal fin crest with three rays (vs. 6–8 in <i>R. glesne</i>); second dorsal fin crest with a single ray (vs. 5–11 in <i>R. glesne</i>; Heemstra 1986c, Olney 2003e, Roberts 2012).</p> <p> <b>Description.</b> Measurements and counts, as well as comparative data, are presented in Table 3. Body highly elongate, ribbon-like, robust, and without scales, but covered by dermal tubercles with circular bases, either with or without a conical or blunt point, more visible and conspicuous at the ventral region and lower sides of the body. Predorsal profile concave, dorsal profile sloping down evenly and in a straight line from the forehead, before the eye, to the caudal region; ventral profile nearly straight (parallel with the body axis) for almost its entire length; posterior to anus, the dorsal and ventral profiles gradually converge forming an elongate and tapered tail. Maximum body depth about two head lengths before pectoral-fin origin.</p> <p>Head length about 19% of snout-vent length; snout length about 192% of eye diameter. Dorsal-fin origin anterior to center of orbit; first four dorsal-fin rays elongated, but broken (the second fin ray about 20% of SL, the third about 21% and the fourth about 15%), subsequent rays relatively short, becoming longer toward the middle region of the body, with the maximum height of fin anterodorsal to the anus; cristophore (see Roberts 2012) present and supports the first dorsal fin crest; pectoral fins low, originating anterior to pelvic-fin origin and their base horizontally oriented, allowing the fin to be vertically oriented when addressed against the body; pelvic fins with a single elongated, but broken, robust ray; caudal fin absent.</p> <p>Color in live (see Figure 2) silvery reddish grey with a silvery light brown head, ocular globes creamy, iris dark and pupils clear; first dorsal-fin rays, dorsal-fin membranes and pelvic-fin rays red; other rays white; 3–5 bands of conspicuous irregularly distributed and variably sized dark spots on the flanks. Color in alcohol light brown, with the anterior region of head darker and flanks with numerous dark spots, distributed as described above.</p> <p> <b>Remarks.</b> Roberts (2012), in his monograph of the oarfish genus <i>Regalecus</i> Ascanius, 1772, recognized only two valid species: <i>R. glesne</i> and <i>R. russelii</i>. The author provide a complete diagnosis of both species that can be clearly separated by differences in several meristic and morphometric characters. The species <i>R. kinoi</i>, originally described from Baja California Sur, Mexico, represents, given this and as previously suggested by other authors (e. g. Salazar-Hermoso <i>et al.</i> 1999), a junior synonym of <i>R. russelii</i> (Roberts 2012).</p> <p>inconspicuous) or unavailable are representeđ with an en-đash (Q).</p> <p> <b> Chávez-Ramos <i>et</i> Castro-Aguirre <i>et</i> Salazar-Hermoso Schmitter-Soto Ruiz & Gosztonyi Character UCR 2478.001 <i>al</i>. (1985) <i>al</i>. (1991±) <i>et al</i>. (1999) (2008) (2010) Morphometrics</b> </p> <p> Our specimen of <i>R. russelii</i> represents, on the basis of Bussing & López (1994, 2005, 2009, 2011), the first documented record of the species in lower Central American (Costa Rican) Pacific waters and, on the basis of Ramírez-Murillo & Schmitter-Soto (1996), Roberts (2012) and Froese & Pauly (2016), a southeast range extension of about 1800 km (straight line) on their known distribution in the eastern Pacific Ocean; the southermost documented record for this species in eastern Pacific waters was on the central coast of Mexico (Ramírez-Murillo & Schmitter-Soto 1996; as <i>R. kinoi</i>).</p>Published as part of <i>Angulo, Arturo & López-Sánchez, Myrna I., 2017, New records of lampriform fishes (Teleostei: Lampriformes) from the Pacific coast of lower Central America, with comments on the diversity, taxonomy and distribution of the Lampriformes in the eastern Pacific Ocean, pp. 573-591 in Zootaxa 4236 (3)</i> on pages 579-582, DOI: 10.11646/zootaxa.4236.3.11, <a href="http://zenodo.org/record/322327">http://zenodo.org/record/322327</a&gt

Peces Costeros del Caribe de Centroamérica Meridional

El presente manual es el tercero de una serie de guías ilustradas para la identificación de los peces marinos de Costa Rica y Centroamérica Meridional. Incluimos en este volumen todas las especies encontradas en aguas costeras de la costa Caribe de Costa Rica: peces de arrecife, demersales o de fondo, pelágicas costeras y especies eurihalinas encontradas generalmente en esteros y pantanos de manglares

Fishes from the Tusubres River basin, Pacific coast, Costa Rica: checklist, identification key and photographic album

A checklist of the fishes of the Tusubres River basin, Pacific coast of Costa Rica, compiled from field and museum surveys is herein presented. A total of 54 species, representing 47 genera and 27 families, were recorded. Peripheral species were dominant (64.8%), followed by secondary freshwater fishes (20.4%); primary freshwater fishes accounted only for 14.8% of the total fish diversity. Eleotridae (6 spp.), Gobiidae (6 spp.), Poeciliidae (5 spp.) and Characidae (4 spp.) were the most diverse. Two species (Caranx sexfasciatus, Carangidae; and Opisthonema libertate, Clupeidae) were new records for Costa Rican freshwaters, and two species (Gymnotus maculosus, Gymnotidae; and Lebiasina boruca, (Lebiasinidae) was found to have expanded ranges. An identification key and a complete photographic album of all fish species recorded in the basin are presented. The results of this investigation provide a framework for future studies on biogeography, ecology and conservation on fishes from this area.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí