Two new species and a review of the inseminating freshwater fish genus Monotocheirodon (Characiformes: Characidae) from Peru and Bolivia

Abstract

Two new species of inseminating freshwater fishes of the genus

Ontogenetic changes in mouth morphology triggers conflicting hypotheses of relationships in characid fishes (Ostariophysi: Characiformes)

“…Phylogenies based on comprehensive samples of characid taxa (Mirande, 2010;Javonillo et al, 2010;Oliveira et al, 2011;Thomaz et al, 2015a) have found the type-species of Odontostoechus grouped to at least one representative of the genus Bryconamericus sensu stricto (Thomaz et al, 2015a), including the genera Hypobrycon and Nantis (currently junior synonyms of Bryconamericus). Alternatively, scenarios based on primary hypotheses of homology through direct comparisons of characteres related to mouth morphology have resulted in completely different hypotheses, grouping B. lethostigmus to genera such as Bryconacidnus, Ceratobranchia, Monotocheirodon, Othonocheirodus, Rhinopetitia, and Rhinobrycon (Böhlke, 1954;Menezes et al, 2013;Netto-Ferreira et al, 2014). However, these hypotheses are based on direct observations and have not been subjected to congruence tests of homology (de Pinna, 1991).…”

“…However, Menezes et al (2013) proposed, like Böhlke (1954), that Odontostoechus was closely related to Bryconacidnus Myers, Ceratobranchia Eigenmann, Monotocheirodon, Othonocheirodus and Rhinopetitia Géry or to these genera plus Rhinobrycon Myers, based on similarities in the mouth shape (Netto-Ferreira et al, 2014). On the other hand, the molecular phylogenies of Javonillo et al (2010) and Oliveira et al (2011) grouped Odontostoechus with Bryconamericus and Hypobrycon Malabarba & Malabarba, and more recently, Thomaz et al (2015a) proposed a new classification for Stevardiinae tribes and genera, placing Odontostoechus as a junior synonym of a monophyletic genus Bryconamericus sensu stricto.…”

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

“…2). The urogenital papilla is more developed in males but smaller in females, in the two species of Monotocheirodon (Menezes et al ., ), in both Phallobrycon species (Menezes et al ., ; Netto‐Ferreira et al ., ) and in M. naponis (Böhlke, , p. 18, fig. 2), whereas in Lophiobrycon weitzmani and in all Gephyrocharax species, it is present only in females (Menezes & Weitzman, , p. 308).…”

“…xaveriellus is a well‐developed, elongated, urogenital papilla (Figure ), which is observed in some Stevardiinae, i.e ., in some Gephyrocharax species— G. caucanus Eigenmann, 1912; G. melanocheir Eigenmann, 1912; G. sinuensis Dahl, 1964; G. torresi Vanega‐Ríos, Azpelicueta, Mirande & Garcia Gonzales; and G. valencia Eigenmann, 1920 (Vanegas‐Ríos, , ); Lophiobrycon weitzmani Castro, Ribeiro, Benine & Melo, 2003 (Menezes & Weitzman, , p. 308, fig. 8); Monotocheirodon drilos Menezes, Weitzman & Quagio‐Grassiotto, 2013; M. kontos Menezes, Weitzman & Quagio‐Grassiotto, 2013 (Menezes et al ., ); Phallobrycon adenacanthus Menezes, Ferreira & Netto‐Ferreira, 2009; and P. synarmacanthus Netto‐Ferreira, Bastos, Sousa & Menezes, 2016 (Menezes et al ., ; Netto‐Ferreira et al ., ), and is also observed in the Cheirodontinae Kolpotocheirodon figueiredoi Malabarba, Lima & Weitzman, 2004 (Malabarba et al ., : fig. 8; Menezes et al ., , p. 54).…”

“…Among the taxa currently included in the subfamily Stethaprioninae, the only species known to have a well-developed urogenital papilla is Moenkhausia naponis Böhlke, 1958(Böhlke, 1958. The urogenital papilla is more developed in males but smaller in females, in the two species of Monotocheirodon (Menezes et al, 2013), in both Phallobrycon species Netto-Ferreira et al, 2016) and in M. naponis (Böhlke, 1958, p. 18, fig. 2), whereas in Lophiobrycon weitzmani and in all Gephyrocharax species, it is present only in females (Menezes & Weitzman, 2009, p. 308).…”