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Three new species of Hemiancistrus (Teleostei: Siluriformes: Loricariidae) from the rio Tocantins basin with comments on the genus

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  • Universidade Federal do Tocantins, Laboratório de Ictiologia Sistemática, Porto Nacional
... The case is similar for Chaetostomus macrops Lütken, 1874, also known from a single specimen from "aquis Surinamensibus", and considered a synonym of megacephalus from the early 20 th century [117] until recently [114,118]. It has a particularly wide and elevated orbital rim reminiscent of that observed in Hemiancistrus medians, from which, however, it is easily distinguished by the absence of keeled and rough-toothed trunk plates [20] and by the presence of odontodes over a broad area on the opercle [114]. ...
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Characterizing and naming species becomes more and more challenging due to the increasing difficulty of accurately delineating specific bounderies. In this context, integrative taxonomy aims to delimit taxonomic units by leveraging the complementarity of multiple data sources (geography, morphology, genetics, etc.). However, while the theoretical framework of integrative taxonomy has been explicitly stated, methods for the simultaneous analysis of multiple data sets are poorly developed and in many cases different information sources are still explored successively. Multi-table methods developed in the field of community ecology provide such an intregrative framework. In particular, multiple co-inertia analysis is flexible enough to allow the integration of morphological, distributional, and genetic data in the same analysis. We have applied this powerfull approach to delimit species boundaries in a group of poorly differentiated catfishes belonging to the genus Guyanancistrus from the Guianas region of northeastern South America. Because the species G. brevispinis has been claimed to be a species complex consisting of five species, particular attention was paid to taxon. Separate analyses indicated the presence of eight distinct species of Guyanancistrus, including five new species and one new genus. However, none of the preliminary analyses revealed different lineages within G. brevispinis, and the multi-table analysis revealed three intraspecific lineages. After taxonomic clarifications and description of the new genus, species and subspecies, a reappraisal of the biogeography of Guyanancistrus members was performed. This analysis revealed three distinct dispersals from the Upper reaches of Amazonian tributaries toward coastal rivers of the Eastern Guianas Ecoregion. The central role played by the Maroni River, as gateway from the Amazon basin, was confirmed. The Maroni River was also found to be a center of speciation for Guyanancistrus (with three species and two subspecies), as well as a source of dispersal of G. brevispinis toward the other main basins of the Eastern Guianas.
... Since then, several species from different regions of South America have been included in this genus. The species come from the Guyana Shield, the Caribbean Sea Basin (Lake Maracaibo, Magdalena, Atrato), the Pacific slope of Panama, Colombia and Ecuador, the basins of the Uruguay River, the Tocantins River and other watersheds in southeastern Brazil (Kner 1854;Günther 1867;Regan 1904Regan , 1913Eigenmann 1916Eigenmann , 1918Schultz 1944;Cardoso & Malabarba 1999;Cardoso & Lucinda 2003;Cardoso 2004;Cardoso & Pezzi 2004;Werneke et al. 2005a, b;de Souza et al. 2008). Four species described from Ecuador, original or subsequently were placed in this genus, the four species were collected on the Pacific slope. ...
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At the Fish Collection of the Instituto de Ciencias Biológicas, Escuela Politécnica Nacional, Quito, three species traditionally grouped in the genus Hemiancistrus were identified: H. annectens (Regan 1904), H. landoni Eigenmann 1916, and a new specie described here. The new species inhabits exclusively in the Esmeraldas River Basin, Pacific slope, northwestern Ecuador. It is easily recognized by the completely naked abdomen, with rounded, dark spots, and a different color pattern on the dorsal and caudal fins. A comparative analysis of bones related to the opercular mobility, shows important differences between H. annectens, H. landoni, and the new species, suggesting that H. annectens does not belong to the genus Hemiancistrus or the Ancistrini group. According to the characteristics observed in these bones, H. annectens shows greater similarity to those reported in species of the Hypostomini group, supporting its inclusion in this group, but placing it in the genus Hypostomus requires further analysis. On the other hand, the conditions observed on the bones of Hemiancistrus landoni and the new species suggest that both are inside of the Ancistrini group. The new species is placed in the genus Hemiancistrus tentatively, pending future analysis.
... Bryconops sensuAlthough some authors reported the presence of Bryconops species in the rio Tocantins (e.g., Lucinda et al Bryconops tocantinensis Bryconops described from the rio Tocantins drainage and may be an additional example of which is recognized by several authors as an area of (e.g.,Cardoso & Lucinda, 2003;Bertaco & Carvalho, 2010; Bertaco et al Comparative material examined. Bryconops alburnoides: Brazil: Amazonas. ...
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A new species of the genus Bryconops, subgenus Bryconops, is described from the rio Conceição, a tributary to the rio Palma, upper rio Tocantins drainage, Tocantins State, Brazil. The new species is distinguished from all its congeners, except B. humeralis and B. vibex by the color pattern in vivo (dorsal, adipose, and caudal fins entirely orange). The new species is easily distinguished from B. humeralis and B. vibex by the absence of a humeral spot and by the lack of maxillary teeth (vs. presence of a single humeral spot and presence of 1-3 maxillary teeth on both sides). Furthermore, the new species is distinguished from B. vibex by the number of perforated lateral line scales (38-41 vs. 44-46). © 2016, Sociedade Brasileira de Ictiologia. All rights reserved.
... Vari, 1988;Menezes & Lucena, 1998;Lima & Moreira, 2003). In its upper part especially, it also appears to represent an area of high endemism for the Ancistrini as shown by the presence of three recently discovered Hemiancistrus species (Cardoso & Lucinda, 2003), and by at least six distinct and apparently endemic species of Ancistrus including those described here. ...
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Three new species of Ancistrus are described: Ancistrus tombador sp. n. from the upper rio Tapajós basin, and Ancistrus reisi sp. n. and Ancistrus jataiensis sp. n. from the upper rio Tocantins basin. The three species differ from their congeners by the absence of an adipose fin. Loss of the adipose fin was only rarely observed in Ancistrini. In the three new species it is replaced by a series of small unpaired platelets forming a low crest. Ancistrus tombador further differs from all congeners by a unique combination of characters: naked margin of snout large and tentacles usually absent in both sexes; body very narrow (cleithral width 27.5-31.2% SL); long caudal peduncle particularly depressed (depth 8.3-9.2% SL). Ancistrus reisi is distinguished from A. jataiensis by measurements, including: predorsal length (respectively: 43.8-46.4% SL versus 47.5-49.3% SL); occipital depth (14.9-17.0% SL versus 17.0-19.5% SL); and caudal peduncle length (27.7-30.9% SL, versus 24.6-27.1% SL).
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Hydropower plants represent one of the greatest threats for freshwater fish by fragmenting the habitat and avoiding the species dispersal. This type of dispersal barrier is often disregarded when predicting freshwater species distribution due to the complexity in inserting the species dispersal routes, and thus the barriers, into the models. Here, we evaluate the impact of including hydroelectric dams into species distribution models through asymmetrical dispersal predictors on the predicted geographic distribution of freshwater fish species. For this, we used asymmetrical dispersal (i.e., AEM) as predictors for modeling the distribution of 29 native fish species of Tocantins-Araguaia River basin. After that, we included the hydropower power plant (HPP) location into the asymmetrical binary matrix for the AEM construction by removing the connections where the HPP is located, representing the downstream disconnection a dam causes in the fish species dispersal route. Besides having higher predicted accuracy, the models using the HPP information generated more realistic predictions, avoiding overpredictions to areas suitable but limited to the species dispersal due to an anthropic barrier. Furthermore, the predictions including HPPs showed higher loss of species richness and nestedness (i.e., loss of species instead of replacement), especially for the southeastern area which concentrates most planned and built HPPs. Therefore, using dispersal constraints in species distribution models increases the reliability of the predictions by avoiding overpredictions based on premise of complete access by the species to any area that is climatically suitable regardless of dispersal barriers or capacity. In conclusion, in this study, we use a novel method of including dispersal constraints into distribution models through a priori insertion of their location within the asymmetrical dispersal predictors, avoiding a posteriori adjustment of the predicted distribution.
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In the scree El Alizal of the Bita river, Puerto Carreño, Vichada, was studied fisherie and reproductive biology of the species Hemiancistrus guahiborum. The fisheries economic unit (FEU) and the parameters of effort and fishing were calculated. Likewise, the fish density in the scree and its distribution pattern were determined using the grid method. By observing the gender and gonadal mature status of monthly caught samples, the breeding season was determined and the total condition factor (K) and the somatic condition factor (K'), the gonadosomatic index, the absolute fecundity (F) and relative fecundity at weight and the mean size of sexual maturity (L50%) were calculated. The FEU was composed by a fisherman and its mask, who using lung freediving, captured 28 ± 18 individuals / fishing,in fishing tasks that lasted 52 ± 20 min. The mean density in the scree river was 0.06 individuals /m2 with a relation variance /mean of 8.86. Mature individuals were observed in all sampled months. Not significant variation in the condition factor (K and K') either gonadosomatic index between months was observed. The F was established in 48 ± 19 oocytes and the relative fecundity was 5.3 ± 0.3 oocytes / g. The maturity size L50% was determined in 6.4 cm and 7.5 cm standard length for females and males, respectively. Parental care in nest was observed in the males. As management strategies are suggested the follows: keep the period of current fishing ban, establish the fishing size in 6 cm SL, ban the trade of mature females, establish breeding areas in the scree rotate the fishing in the scree river and stimulate the captive breeding of the species.
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