Examinando por Materia "Taxonomy"
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- PublicaciónSólo datosA new species of Pimelodella Eigenmann & Eigenmann, 1888 (Siluriformes: Heptapteridae) from the Sierra Nevada de Santa Marta, Colombia(Zootaxa, 2019-09-12) Conde-Saldaña, Cristhian; Albornoz-Garzón, Juan Gabriel; Garcia Melo, Jorge Enrique; Dergam, Jorge; Villa-Navarro, Francisco AntonioA new species of Pimelodella is described from northern coastal drainages of the Sierra Nevada de Santa Marta (SNSM), Colombia. The new species is diagnosed from all trans-Andean congeners by the following unique combination of characters: head length 22.2–23.7% SL, bony interorbital width 17.6–21.6% HL, maxillary barbels length 53.0–68.3% SL, inner mental-barbels length 14.4–20.0% SL, body width 17.6–21.1% SL, dorsal-fin spine length 8.3–13.7% SL, dorsal-fin base 12.3–14.9% SL, pectoral-fin spine length 12.9-14.5% SL, pectoral-fin spine length without dentations on the distal posterior margin 21.6–29.8% in pectoral-fin spine length, maximum depth of dentations in posterior margin of pectoral-fin spine 1.40–1.68 times in the width of the spine at its base, adipose-fin base length 22.8–26.4% SL, caudal-peduncle depth 9.2–10.5% SL, 40 vertebrae, having a conspicuous paired dark brown stripe on the dorsal surface of body, extending from posterior margin of head to caudal-fin insertion and a wide dark brown midlateral stripe present. The isolated occurrence of this new taxon living in allopatry in coastal drainages of the SNSM could have interesting biogeographic implications for dispersal and vicariance processes of the ichthyofauna from northern South America.
- PublicaciónSólo datosBinarization method for chromosomal analysis of primitive plants: the case of Zamia tolimensis and Zamia huilensis (Cycadales, Zamiaceae)(Proceedings of SPIE - The International Society for Optical Engineering, 2021-08-01) Torres-Benítez, Alfredo; Aldana, María; Forero, Manuel G.Cytogenetic studies of plants allow integration with taxonomic and systematic data for the formulation of conservation strategies. However, traditional methods of microscopy image analysis for chromosome observation and identification are inefficient in species considered primitive and with critically endangered wild populations. For this reason, the objective of this work is to establish an image processing method that will facilitate the distinction of chromosomes in Zamia tolimensis and Zamia huilensis plants endemic to Colombia. For this purpose, metaphase plates and photographs of both species were acquired under the microscope, which was superimposed and their contrast adjusted, to obtain a composite image with species-specific dispositions and transparencies. The proposed technique, based on thresholding techniques, allows a better analysis of the images obtained. Thus, the delimited areas of chromosomes in the binarized images were shown with greater precision for the counting and measurement of genetic structures, with a total of 27 and 26 chromosomes in Z. tolimensis and Z. huilensis, respectively. The technique complements and simplifies the counting and interpretation of plant genetic information obtained by classical computational methods.
- PublicaciónSólo datosSpecies delimitation reveals an underestimated diversity of Andean catfishes of the family Astroblepidae (Teleostei: Siluriformes)(Neotropical Ichthyology, 2020-12-04) Ochoa, Luz E.; Melo, Bruno F.; García-Melo, Jorge E.; Maldonado-Ocampo, Javier A.; Souza, Camila S.; Albornoz-Garzón, Juan G.; Villa-Navarro, Francisco; Conde-Saldaña, Cristhian C.; Ortega-Lara, Armando; Oliveira, ClaudioCatfishes of the family Astroblepidae form a group composed by 82 valid species of the genus Astroblepus inhabiting high-gradient streams and rivers throughout tropical portions of the Andean Cordillera. Little has been advanced in the systematics and biodiversity of astroblepids other than an unpublished thesis, a single regional multilocus study and isolated species descriptions. Here, we examined 208 specimens of Astroblepus that apparently belong to 16 valid species from several piedmont rivers from northern Colombia to southern Peru. Using three single-locus approaches for species delimitation in combination with a species tree analysis estimated from three mitochondrial genes, we identified a total of 25 well-delimited lineages including eight valid and 17 potential undescribed species distributed in two monophyletic groups: the Central Andes Clade, which contains 14 lineages from piedmont rivers of the Peruvian Amazon, and the Northern Andes Clade with 11 lineages from trans- and cis-Andean rivers of Colombia and Ecuador, including the Orinoco, Amazon, and Magdalena-Cauca basins and Pacific coastal drainages. Results of species delimitation methods highlight several taxonomical incongruences in recently described species denoting potential synonymies.