Neblinichthys echinasus , holotype, CSBD 1652, 82.9 mm SL, Kukui River, near town of Philipai, upper Mazaruni River drainage. 

Neblinichthys echinasus , holotype, CSBD 1652, 82.9 mm SL, Kukui River, near town of Philipai, upper Mazaruni River drainage. 

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Neblinichthys brevibracchium and N. echinasus are new sympatric species from upland tributaries of the Mazaruni River (Essequibo River basin) of Guyana. These two new species are the first Neblinichthys reported from Guyana. Adult males of both new species have short pectoral-fin spines and several series of hypertrophied odontodes covering the ent...

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Context 1
... from N. brevibracchium by a larger dorsal- fin base/SL ratio (24.3-27.0% vs. 18.1-22.8%), a smaller dorsal- anal distance/SL ratio (11.9-12.5% vs. 13.7-18.3%), by having the snout tapering shallowly and continuously from eyes to snout tip (vs. snout decreasing in steep arc just anterior to eyes and then flattening in area anterior of nares; Fig. 3), and by having the adpressed dorsal fin reaching the anterior preadipose plate (vs. not reaching anterior preadipose plate). From N. pilosus and N. roraima by having the odontodes along the edge of the snout of nuptial males longer than those on the top of the snout (vs. odontodes on the front edge of the snout much longer than those ...
Context 2
... inner papillated surfaces pale tan but brown with white spots on outer anterior margin. All fin spines and rays with alternating wide dark and narrow light bands (pattern most evident in caudal and dorsal fins, least evident in pectorals); fin membranes dark gray in holotype, hyaline in paratypes. Base of anteriormost dorsal-fin membrane black (Fig. ...
Context 3
... dimorphism. Presumed males have extremely hypertrophied odontodes along the entire edge of the snout with the odontodes becoming slightly shorter posteriorly. just prior to the evertible cheek plates (Fig. 3). Three rows of hypertrophied odontodes on present on the snout, the medial row is relatively short and located on the mesethmoid; the lateral rows are also relatively short, extending from eyes to nares and then intermediate from nares to snout. The areas between the snout edge and the rows of odontodes have some hypertrophied ...

Citations

... Above Kaieteur Falls in the Potaro River to the south of the Kuribrong River, Eigenmann (1912) recorded Lithogenes villosus, the type species of a genus that has been recovered as sister to either all other Astroblepidae (Hardman, 2005;Armbruster, 2008) or all other Loricariidae (Schaefer, 2003). And isolated in the upper Mazaruni, above numerous cataracts and waterfalls, is a diverse assemblage of almost entirely endemic taxa in the families Cichlidae (Mazarunia spp.; Ló pez-Fernández et al., 2012), Crenuchidae (Skiotocharax meizon, Presswell et al., 2000), Lebiasinidae (Lebiasina ardilai;Netto-Ferreira et al., 2013;Derhamia hoffmannorum;Géry and Zarske, 2002), Loricariidae (Neblinichthys spp.; Taphorn et al., 2010;Paulasquama callis;Armbruster and Taphorn, 2011), and Parodontidae (Apareidon agmatos; Taphorn et al., 2008). ...
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Characidium amaila, new species, is described from rapids of the upper Kuribrong River (Potaro-Essequibo drainage) upstream of Amaila Falls. It is diagnosed from most other species of Characidium by lacking scales on the isthmus and chest, and by having 8-13 premaxillary teeth, the first four pectoral-fin rays noticeably thickened, 34-36 lateral line scales, and branchiostegal membranes that are free from each other across the isthmus. Characidium amaila is further distinguished by its large adult body size (max. = 85.5 mm SL), and by having a tan body base color with a dark midlateral stripe that originates on the upper lip and continues posteriorly to the base of the middle caudal-fin rays, a gray to dark-black dorsum with two horizontal rows of small light spots formed by aligned light-colored scale centers, a dark humeral spot, up to 15 irregular black bars that extend from dorsum to lower sides, a light opercular margin, and fins that are uniformly dusky. Several cranial, vertebral, and swim bladder characteristics also support distinctiveness of the new species.
... Neblinichthys was originally described as a new genus from specimens collected from a stream that drains Pico Neblina in southern Venezuela (Ferraris et al., 1986). Since that time, three other species were described in the genus, and Ancistrus yaravi Steindachner was recognized as belonging to Neblinichthys (Provenzano et al., 1995;Taphorn et al., 2010). Neblinichthys is a member of the Ancistrus clade of the Ancistrini, (Hypostominae), and was found to either be a member of a polytomy of all Ancistrus clade except Pseudancistrus (Armbruster, 2004) or as sister to all Ancistrus clade members except Dekeyseria and Pseudancistrus (Armbruster, 2008); however, support for any relationships of Neblinichthys within the Ancistrus clade is weak. ...
... relative size difference). Comparative material is listed in Taphorn et al. (2010). There was an error in tables of Taphorn et al. (2010), and "% Head Length" is actually "% Predorsal Length". ...
... Comparative material is listed in Taphorn et al. (2010). There was an error in tables of Taphorn et al. (2010), and "% Head Length" is actually "% Predorsal Length". Correct values are in Table 1. ...
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Neblinichthys peniculatus is described from specimens collected in the río Carapo (río Paragua - río Caroni drainage), which drains the southern flank of Cerro Guaiquinima in southeastern Venezuela. Neblinichthys peniculatus differs from all congeners by having mottling on the caudal peduncle consisting of dark spots and dashes (vs. caudal peduncle all about the same color or light below and dark above) and by having spots on the head (spots less conspicuous in nuptial males as the head is darker; vs. no spots). Uniquely among Neblinichthys for which nuptial males are known, the hypertrophied odontodes on the snout are rather short, none as large as the eye diameter.
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The Pakaraima Mountains are an ancient mountain range along the borders of Guyana, Brazil, and Venezuela. The high plateau is drained by multiple river systems in all directions. Although hypotheses have been presented for the biogeographic relationships of lowland rivers, the interconnectivity of rivers on the top of the plateau is unknown. With multiple complex rivers in a small, upland area we predicted a high level of endemism for stream fishes and complex biogeographic relationships. We explore this with the incredibly diverse pencil catfish genus Trichomycterus. Using collections from recent expeditions to the Pakaraima Mountains of Guyana, we amplified three mitochondrial (16S, COI, and cytb) and two nuclear markers (myh6 and RAG2). We constructed individual gene trees as well as a concatenated tree to determine the placement of these taxa within the Trichomycterus of the trans-Andean/Amazonian clade. Herein, we identify six endemic lineages of Trichomycterus from the highlands of the Pakaraima Mountains. Of the identified lineages, we find two species occupying multiple basins, suggesting that Pakaraima streams either maintain or had some degree of recent connectivity.
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PLEASE SEE THE FINAL PAPER PUBLISHED WITH BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY https://dx.doi.org/10.1093/biolinnean/blaa023 Aim: The Pakaraima Mountains are an ancient mountain range along the borders of Guyana, Brazil, and Venezuela. The high plateau is drained by multiple river systems in all directions. Although hypotheses have been presented for the biogeographic relationships of lowland rivers, the interconnectivity of rivers on the top of the plateau is unknown. With multiple complex rivers in a small, upland area we predicted a high level of endemism for stream fishes and complex biogeographic relationships. We explore this with the incredibly diverse pencil catfish genus Trichomycterus . Only two species are known from the region. In this study, we 1) confirm the discovery of multiple endemic Trichomycterus species in the region, 2) determine the phylogenetic placement of our samples to posit biogeographical scenarios, and 3) provide clarification for the identification of T. guianensis based on morphology. Location: Pakaraima Mountains, a part of the Guiana Shield in Guyana, South America. Taxon: Pencil catfish genus Trichomycterus . Methods: Using collections from recent expeditions to the Pakaraima Mountains of Guyana, we amplified three mitochondrial (16S, COI, and cytb) and two nuclear markers (myh6 and RAG2). We constructed individual gene trees as well as a concatenated tree to determine the placement of these taxa within the Trichomycterus of the Trans-andean/Amazonian clade. Results: Our results identify six unique lineages in the highlands of Guyana. Only two species, Trichomycterus guianensis and T. conradi , were previously known to science. Main Conclusions: The Pakaraima Mountains of South America are a region of high endemism, as demonstrated here in Trichomycterus catfishes. We find two species occupying multiple basins, suggesting that Pakaraima streams either maintain or had some degree of recent connectivity. We identify six endemic lineages of Trichomycterus from the highlands of the Pakaraima Mountains. The upper portions of the study rivers have been connected either through surface flow or by stream capture. Both processes have occurred on multiple time scales and are independent of the patterns seen in the lowlands.
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Lebiasina ardilai is described from the upper Mazaruni in Guyana. The new species differs from all its congeners by its color pattern consisting of: a narrow, nearly straight primary stripe, extending from posterior to humeral blotch to near the vertical through anal-fin origin, being absent or inconspicuous in females and conspicuously marked in males; the presence of four series of dark blotches at the distal border of the scales of longitudinal series 2–5; the faint secondary stripe running onto scales of second and third longitudinal row of scales; intermediate stripe absent; and the posteriorly displaced caudal blotch, not reaching the posterior tip of caudal peduncle.
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We expand the description of the genus Mazarunia Kullander, 1990, explore morphological diagnostic characters for the genus and for its sister-group relationship with Guianacara Kullander & Nijssen, 1989 in a phylogenetic context, expand the description of M. mazarunii and describe two new species. Mazarunia can be diagnosed by the combination of numerous anatomical traits, including the unique loss of infraorbital 6, the configuration of the first epibranchial in two of the species, a well-developed posteroventral lateral expansion of the palatine that is largely contiguous with the ectopterygoid, the absence of a suture between the hyomandibular and the metapterygoid, the absence of an interarcual cartilage, fourth ceratobranchial with 2 or 3 tooth plates, a caudally scaled interoperculum, equal-sized scales in the ventral and lateral chest regions, a simple, disjunct pattern of lateral line squamation, and smooth preopercle, supracleithrum and extrascapula. Species of Mazarunia can be further distinguished from species of their sistergenus Guianacara by their distinct color patterns. Mazarunia charadrica, new species, can be distinguished from other species of Mazarunia, among other characters, by approximately equal uncinate process and anterior arm and reduced anteroventral expansion of epibranchial 1 (vs. uncinate process narrower and complete anteroventral expansion in the other two species), a dorso-ventrally flattened maxillary process of the palatine (vs. cylindrical in the other two species), cycloid (vs. ctenoid) scales in the opercular, postorbital, lateral chest and anal-genital regions, the absence of a mid-lateral spot, and a diffuse dark area covering the dorsal portion of the head giving the impression of a “black cap”. Mazarunia charadrica has a unique juvenile pattern of seven vertical dark bars partially preserved in adults. Bars 3-6 in antero-caudal direction are most visible in juveniles and edium-sized specimens but become fainter and almost disappear in adults. Many specimens show only bar number 3 (midlateral bar). Mazarunia mazarunii can be distinguished from all other species of Mazarunia by the presence of two foramina (vs. one) on the lateral face of the ascending process of the premaxilla, a lachrymal bone that is longer than deep (vs. deeper than long), an infraorbital 3 that is contiguous but not overlapping with the lachrymal (vs. overlapping), ctenoid scales (vs. cycloid) on the subopercle, interopercle and chest, and by its unique coloration, including complete suborbital and supraorbital stripes, and being the only species of Mazarunia with a discernible lateral band formed by the mid-line blotching pattern associated with lateral bars. In large adults, M. mazarunii has a black or dark bar behind the head that produces the impression of a collar. Mazarunia pala, new species, can be distinguished from its congeners by the absence of a parhypurapophysis, the presence of a dorsal-fin scaly pad with ctenoid scales (vs. no scaly pad in M. charadrica and M. mazarunii), a small suborbital stripe limited to the preopercle, the absence of clearly discernible lateral bars on the body, and by its general pinkish coloration with midlateral spot as the only melanic marking. All known species of Mazarunia are restricted to the upper reaches of the Mazaruni River basin in Guyana.