Description of <i>Loraxichthys lexa</i>, new genus and species (Siluriformes: Loricariidae) from the Río Huallaga Basin, central Peru, with notes on the morphology of the enigmatic <i>Lipopterichthys carrioni</i> Norman, 1935

Abstract

A new genus and species of armored catfish, Loraxichthys lexa, collected in 1955 by the Catherwood Foundation Peruvian-Amazon Expedition from the vicinity of Tingo María, Huánuco, is described herein. Loraxichthys is diagnosed by two uniquely derived characters: two to four robust evertible posterior cheek odontodes with hooked tips, longer than odontodes anterior to them but no more than twice their length; and skin folds on dorsal border along first pelvic-fin ray crenulated in mature males. Loraxichthys lexa, new species, is only known from clear water tributaries of the Río Huallaga in the vicinity of Tingo María. Additionally, notes on the morphology of the enigmatic species Lipopterichthys carrioni are included, and an artificial key for the genera Chaetostoma, Cordylancistrus, Dolichancistrus, Leptoancistrus, Lipopterichthys, and Loraxichthys is provided.Key words: Ancistrinae, Andes, biodiversity, conservation, endemic ResúmenUn nuevo género y especie de carachama, Loraxichthys lexa, colectada en 1955 por la Catherwood Foundation PeruvianAmazon Expedition en los alrededores de Tingo María, Huánuco, es descrita. Loraxichthys se diagnostica en base a dos características derivadas únicas: dos a cuatro odontodes evertibles de la mejilla robustos, con extremos ganchudos, más largos que los odontodes anteriores a ellos, pero no más de dos veces el largo de estos; y, pliegues carnosos en el borde dorsal del primer radio de la aleta pélvica festoneados, en especímenes machos maduros. Loraxichthys lexa, especie nueva, sólo se conoce de tributarios de aguas claras del Río Huallaga en los alrededores de Tingo María. Adicionalmente, se incluyen notas sobre la morfología de la enigmática especie Lipopterichthys carrioni y se provee una clave artificial para identificar a los géneros Chaetostoma, Cordylancistrus, Dolichancistrus, Leptoancistrus, Lipopterichthys, y Loraxichthys.

Two NewChaetostomaGroup (Loricariidae: Hypostominae) Sister Genera from Opposite Sides of the Andes Mountains in Ecuador, with the Description of One New Species

“…To date, there has been no comprehensive examination of relationships between all five species of Cordylancistrus; however, every phylogenetic study that has examined more than a single species has found them to be paraphyletic with respect to other closely related genera (i.e., Dolichancistrus, Leptoancistrus). These include two studies based on morphological data (Armbruster, 2008;Salcedo, 2013) and two studies based on molecular data (Lujan et al, 2015, in press). The most comprehensive of these is that by Lujan et al (in press), which examines relationships between four valid species (Co. aequinoctialis, Co. torbesensis, Co. platycephalus, and Co. santarosensis), and one species described herein as new.…”

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

“…C. chimu differs from congeners except C. anale , Chaetostoma bifurcum Lujan et al ., 2015a, C. breve , C. brevilabiatum , Chaetostoma changae Salcedo, 2006, Chaetostoma daidalmatos Salcedo, 2006, Chaetostoma dermorhynchum Boulenger, 1887, Chaetostoma dupouii Fernández‐Yépez, 1945, C. fischeri Steindachner, 1879, C. formosae , Chaetostoma floridablancaense , Chaetostoma guairense Steindachner, 1881, Chaetostoma jegui Rapp Py‐Daniel, 1991, C. joropo , C. lepturum Regan, 1912, C. leucomelas , Chaetostoma lineopunctatum Eigenmann & Allen, 1942, C. marginatum , C. milesi , C. niveum , C. palmeri , C. patiae , C. paucispinis , Chaetostoma pearsei Eigenmann, 1920, Chaetostoma stannii Lütken, 1874, Chaetostoma stroumpoulos Salcedo, 2006, C. tachiraense , Chaetostoma taczanowskii Steindachner, 1882, C. thomsoni , Chaetostoma trimaculineum Lujan et al ., 2015a, C. vagum (new synonym of C. anale , see below), Chaetostoma vasquezi Lasso & Provenzano, 1998, Chaetostoma venezuelae (Schultz, 1944) and Chaetostoma yurubiense Ceas & Page, 1996, by having curved cheek odontodes ( vs . cheek odontodes straight through most or all of odontode length in C. anomalum , Chaetostoma branickii Steindachner, 1881, Chaetostoma carrioni (Norman, 1935), C. dorsale , Chaetostoma lexa (Salcedo, 2013), Chaetostoma loborhynchos Tschudi, 1846, Chaetostoma machiquense Fernández‐Yépez & Martín Salazar, 1953, Chaetostoma marmorescens Eigenmann & Allen, 1942, Chaetostoma microps Günther, 1864, Chaetostoma nudirostre Lütken, 1874, C. platyrhynchus , C. sovichthys and Chaetostoma spondylus Salcedo & Ortega, 2015). Chaetostoma chimu further differs from species with straight cheek odontodes in addition to C. guairense and C. pearsei by having a parieto‐supraoccipital excrescence ( vs .…”

“…This genus is one of the most species‐rich of the subfamily Hypostominae along with Hypostomus and Ancistrus , and is in need of taxonomic review with several species of uncertain validity, and a number of undescribed species. Although there have been different works dealing with the taxonomy of Peruvian and Ecuadorian species of Chaetostoma (Lujan et al ., 2015a, 2015c; Salcedo, 2006, 2013; Salcedo et al ., 2011; Salcedo & Ortega, 2015), the status of Colombian and especially Venezuelan species is comparatively poorer, despite modest efforts in the past (Ballen, 2011; Ballen et al ., 2016). Currently 23 species have been documented in Colombia, which represents about half the known diversity in the genus.…”

A new species of Chaetostoma, an armored catfish (Siluriformes: Loricariidae), from the río Marañón drainage, Amazon basin, Peru

“…However, Lipopterichthys Norman and Loraxichthys Salcedo also exhibit these traits. Chaetostoma differs externally from Lipopterichthys by having 14 (vs. 12) branched caudalfin rays, from Loraxichthys by having short (vs. long) hypertrophied evertible odontodes on three cheek plates, and from both genera by having an adipose fin (Salcedo, 2013).…”