A new species of rheophilic armored catfish of Rineloricaria (Siluriformes: Loricariidae) from the Vaupés River, Amazonas basin, Colombia

A new rheophilic species of the genus Rineloricaria is described for the Amazon basin in Colombia. Rineloricaria cachivera n. sp. differs from its congeners by having anterior to the first predorsal plate, an inconspicuous saddle-like mark; the presence of dark, diffuse blotches, present as unified dark colouration along most of the dorsal portion of the head, without bands or spots on the head; a long snout that occupies more than half the head length (HL), between 58.0% and 66.3% HL; a naked portion on the cleithral area from the border of lower lip reaching the origin of pectoral fin; and by having five series of lateral plates in longitudinal rows below the dorsal fin. The new species is morphologically similar to Rineloricaria daraha; however, it can be distinguished by the presence of six branched pectoral fin rays (vs. seven) and the lower lip surface with short thick papillae (vs. long finger papillae). An identification key to the Rineloricaria species of the Amazon River basin in Colombia is provided. The new species is herein categorized as Least Concern, following the IUCN criteria.

Fishes from the Colombian Amazonia region: species composition from the river systems within the rainforest biome

Abstract The Colombian Amazon region is part of the Neotropical rainforest (humid forest biome) covering an area of 483,163 km2 and includes tributaries of both the Amazon and Orinoco River basins. The aquatic ecosystems found there include: rivers and alluvial plains originating in Andean headwaters, on eroded soils of tropical forests in the lowlands, and Guiana Shield formations, comprising a dense fluvial drainage network in the lowlands, with Paleogene/Neogene geological formations (terra firme streams in higher places that don’t usually flood) and Paleozoic (shield streams); and Andean and Guiana Shield streams above 200–250 m a.s.l. We present here an exhaustive compilation of published information, supported by fish collections, consisting of a list of 1104 species distributed in 375 genera, 53 families, and 16 orders. We include occurrence data of these species in each sub-basin. The presence/absence species matrix was analyzed using a dendrogram and non-metric multidimensional scaling (NMDS) analysis to identify patterns of similarity between basins and sub-basins. We evaluated species composition between basins and among the different geological origins using PERMANOVA. The dendrogram shows co-occurrences of 404 species in the two basins. It also shows two clear groupings of the sub-basins of the Amazon (except Guainía-Negro drainages) and those of the Orinoco. Within the Amazon Basin, there are two nodes according to the geological origin: systems of Andean origin and those of the lowlands. The dendrogram results are consistent with the NMDS analysis, which shows a clear grouping according to the connectivity of the basins; the Guainía-Negro is included in the Amazon basin. Species distribution patterns were supported by the PERMANOVA, and differed significantly between basins (F = 4.3, R = 0.26, P = 0.003) and geological origin (F = 3.6, R = 0.23, P = 0.003). The number of species in this study represents almost a fifth of the ichthyofauna of the Neotropics and about a third of that of the Amazon River basin; clearly supporting Colombia’s status among the countries with the greatest diversity of freshwater fish species of the planet. We include here a significant number of new records (75 spp), provide a first approximation of the distribution patterns, and a framework for future biogeographical studies.

A new species of Chaetostoma (Siluriformes: Loricariidae) from the Orinoco basin with comments on Amazonian species of the genus in Colombia

Chaetostoma chimu sp. nov. is described from 119 specimens collected in the Andean foothills of the Orinoco River in Colombia. The new species can be distinguished from congeners by a combination of characters, including shape of cheek odontodes, presence of a supraoccipital excrescence, sexual dimorphism characters and colour pattern. In addition, this species can be distinguished from the sympatric and geographically close congeners of the Orinoco that have curved cheek odontodes (i.e., Chaetostoma anale, Chaetostoma formosae and Chaetostoma joropo), by presenting a generally larger orbital diameter and interorbital distance, details of sexual dimorphism and colour pattern. The type locality of specimens collected by Kjell von Sneidern in the mid-twentieth century in the Colombian Amazon is also clarified. Chaetostoma alternifasciatum and Chaetostoma vagum are proposed as junior synonyms of C. anale. An identification key for the species of Chaetostoma from cis-Andean drainages in Colombia is provided. The new species is herein categorized as Vulnerable (Vu) B1a (i, iii), following the IUCN criteria.

Loricaria cuffyi (Siluriformes: Loricariidae), a new species of loricariin catfish from the Guiana Shield

Loricaria cuffyi n. sp. is described based on 36 specimens from the Essequibo and upper Negro River drainages in western Guyana and the upper Orinoco River drainage in Venezuela. The new species can be distinguished from sympatric and geographically proximate congeners by a postorbital notch that is inconspicuous, shallow and rounded, odontode ridges on the dorsum of head and predorsal weakly developed, abdominal plates tightly joined and completely covering the median abdominal space and pectoral girdle, higher anterior lateral plate counts, and coloration characteristics. The distribution of the new species adds to an interesting and well-documented biogeographical pattern exhibited by other Guiana Shield loricariids influenced by the proto-Berbice during the Cenozoic and recent configuration of drainages in the Guiana Shield. We present an update on the taxonomy of Loricaria, and discuss the biogeography and conservation status of the new species.

A new species of Hyphessobrycon Durbin (Characiformes: Characidae) from the western Amazon basin in Colombia and Peru

Hyphessobrycon chiribiquete n. sp. is described from the Río Caquetá drainage in Colombia and the Río Ucayali drainage in Peru, western Amazon. The new species is diagnosed from its congeners by having the following combination of characters: a conspicuous narrow midlateral stripe, starting on the sides of the body behind the opercle near the lateral line; lateral stripe overlapped anteriorly with a vertically elongated humeral blotch; inner premaxillary teeth pentacuspid; margin of anal fin falcate in mature males.

A new Hemigrammus from the upper Río Vaupés, Colombia (Characiformes: Characidae), with a discussion on the presence of an enlarged urogenital papilla in the family

Hemigrammus xaveriellus sp. nov. is described from the upper Río Vaupés basin (Amazon basin), Departamento Guaviare, Colombia. It is distinguished from all congeners by the combination of the following characters: presence of a conspicuous, dark, longitudinal midlateral stripe extending along the body; presence of a conspicuous rounded, horizontally elongated humeral blotch anterior to the beginning of the dark midlateral stripe; seven scale rows between the dorsal fin and lateral line (vs. five to six); and five scale rows between the lateral line and pelvic-fin insertion (vs. three to four). The single mature male of He. xaveriellus possessed a well-developed urogenital papilla, an unusual feature among characids. The presence of an enlarged urogenital papilla in the family is discussed, and comments regarding the putative relationships of the new species are presented.

Moenkhausia hemigrammoides Géry, 1965 (Characidae, Stethaprioninae) in Colombia: new records and comments on morphology

Moenkhausia hemigrammoides Géry, 1965 was described from Suriname and recently found in the Ariari drainage, part of the Orinoco river basin. Here, we formally report the presence of this species in the Ariari and Inírida drainages of the Guaviare River and present morphological data that complement the original description. Our records of M. hemigrammoides represent the westernmost distribution for this Guianan species in the Amazonas–Orinoco transition zone.

Fishes of the Cusiana River (Meta River basin, Colombia), with an identification key to its species

The Cusiana River sub-basin has been identified as a priority conservation area in the Orinoco region in Colombia due to its high species diversity. This study presents an updated checklist and identification key for fishes of the Cusiana River sub-basin. The checklist was assembled through direct examination of specimens deposited in the main Colombian ichthyological collections. A total of 2020 lots from 167 different localities from the Cusiana River sub-basin were examined and ranged from 153 to 2970 m in elevation. The highest number of records were from the piedmont region (1091, 54.0 %), followed by the Llanos (878, 43.5 %) and Andean (51, 2.5 %). 241 species distributed in 9 orders, 40 families, and 158 genera were found. The fish species richness observed (241), represents 77.7 % of the 314 estimated species (95 % CI=276.1-394.8). The use of databases to develop lists of fish species is not entirely reliable; therefore taxonomic verification of specimens in collections is essential. The results will facilitate comparisons with other sub-basins of the Orinoquia, which are not categorized as areas of importance for conservation in Colombia.

A new species of Chrysobrycon (Characiformes, Characidae, Stevardiinae) from the Amazon River basin in Colombia, with a new diagnostic characteristic for the genus

Chrysobrycon mojicai sp. nov. is described from forest streams that are part of the Amazon River basin in Colombia. It is distinguished from all congeners by having most of the maxillary teeth with distal tips lateroventrally curved (v. teeth straight along their lengths) and a greater number of dentary teeth (20-27 v. 11-19, except in Chrysobrycon yoliae). The posterior margin of the ventral process of the quadrate does not reach the vertical through the posterior margin of the symplectic and these features differentiate C. mojicai from Chrysobrycon myersi and C. yoliae (v. posterior margin of ventral process of quadrate reaching vertical through posterior margin of symplectic). In species of Chrysobrycon, the frontals are extensively contacting each other along the midline, resulting in an absent frontal fontanel and a reduced parietal fontanel. This extensive contact between the frontals modifying the fontanels is a condition rarely found within the Stevardiinae and hence is proposed as an additional diagnostic characteristic for the genus. An updated identification key for all Chrysobrycon species is provided.

A new species of Hyphessobrycon (Characiformes, Characidae) from the upper Guaviare River, Orinoco River Basin, Colombia

Hyphessobryconklausannisp. n. is described from small drainages of the upper Guaviare River (Orinoco River Basin) in Colombia. It differs from all congeners by having a wide, conspicuous, dark lateral stripe extending from the anterior margin of the eye across the body and continued through the middle caudal-fin rays, and that covers (vertically) three or four horizontal scale rows. It also differs by having an orange-yellow stripe extending from the anterosuperior margin of the eye to the caudal peduncle above the lateral line in life. It differs from all other species of Hyphessobrycon that have a similar dark lateral stripe: H.cyanotaenia, H.loretoensis, H.melanostichos, H.nigricinctus, H.herbertaxelrodi, H.eschwartzae, H.montogoi, H.psittacus, H.metae, H.margitae, H.vanzolinii, and H.peruvianus in having only three or four pored scales in the lateral line, 21 to 24 lateral scales and six teeth in the inner premaxillary row. Hyphessobryconklausanni differs from H.loretoensis in having seven to eight maxillary teeth (vs. three to four) and in having a longer caudal peduncle (12.4–17.0% SL vs. 4.6–8.0% SL). Additionally Hyphessobryconklausanni can be distinguished from the other species of Hyphessobrycon with a dark lateral stripe from the Orinoco River Basin (H.metae and H.acaciae) in having two teeth in the outer premaxillary row (vs. three to four) and 10 branched pectoral–fin rays (vs. 11 to 12). It further differs from H.metae by the length of the snout (17.6–22.8% HL vs. 9.9–15.2% HL) and by the length of the caudal peduncle (12.4–17.0% SL vs. 7.3–11.8% SL).

Description of a new species of the genus Chaetostoma from the Orinoco River drainage with comments on Chaetostoma milesi Fowler, 1941 (Siluriformes: Loricariidae)

Chaetostoma joropo n. sp. is described from the piedmont of the Orinoco River drainage in Colombia. The new species has been long confused with Chaetostoma milesi, a species with similar overall morphology and color pattern that is restricted to the Magdalena-Cauca River Basin. We diagnose the new species on the basis of morphology as well as a precise description of the color pattern. Chaetostoma joropo n. sp. is also easily distinguished from C. formosae the most similar species and other species inhabiting the Orinoco River drainage in Colombia. Data on ontogenetic variation and sexual dimorphism are provided, as well as natural history notes and remarks on the usage of the name Chaetostoma milesi for specimens from both the Orinoco and Magdalena-Cauca drainages. A discussion on the usage of the name Chaetostoma platyrhynchus is also provided given its current instability in the literature.