New finding of Rhadinoloricaria macromystax (Siluriformes: Loricariidae): redescription of the genus and description of a new species from Ecuador

Abstract

The fish collection from the Museum of Escuela Politécnica Nacional, Quito, Ecuador, has nine lots with 12 specimens assigned to genus Rhadinoloricaria. Specimens come from the Napo and Pastaza rivers, Amazon River basin, eastern Ecuador. One specimen matches accurately with figures and original description of Loricaria macromystax Günther, 1869, type species of Rhadinoloricaria. After 150 years, this is the first secure identification of the species, which allowed an accurate description of the genus Rhadinoloricaria, and the discovery of a new species from Ecuador, described herein. In addition, using available specimens, figures and literature, a comparative analysis on external morphology was performed among the eight species included in Rhadinoloricaria. The analysis documented significant differences between them, in some morphological external characters and in buccal ornamentation. The results suggest that the eight species can be grouped into three or four genera. Rhadinoloricaria, in strict sense, has two species. Apistoloricaria is considered a valid genus, and include the four species previously assigned to it. Rhadinoloricaria bahuaja and R. rhami do not belong to the known genera in the Pseudohemiodon group. At this time, available data suggests that both species could continue included in ‘Rhadinoloricaria’, waiting further analyses to solve their generic status. Results support the use of buccal ornamentation patterns alone or combined with some morphological characters as valuable tool for generic identification within Loricariini.

A new species of mailed catfish of genus Rhadinoloricaria (Siluriformes: Loricariidae: Loricariinae) from Rio Negro basin, Brazil

“…and Rhadinoloricaria “Orinoco”) are sister of a clade composed of R. macromystax , R. ommation , R. bahuaja and R. rhami . Recently, Provenzano‐Rizzi and Barriga‐Salazar (2020) suggest the revalidation of the genus Apistoloricaria (previously synonymised with Rhadinoloricaria by Covain et al ., 2016) based on putative derived characters shared among Apistoloricaria species. The results of this study are in accordance with Covain et al .…”

“…Provenzano‐Rizzi and Barriga‐Salazar (2020) stated that the species of Rhadinoloricaria are rare. Loricaria macromystax (Günther, 1869) (now R. macromystax ) was described from a single specimen and R. stewarti was described with just six specimens.…”

“…Buccal ornamentation is an important character to allocate the species of Pseudohemiodon group (Provenzano‐Rizzi & Barriga‐Salazar, 2020; Rojas‐Molina et al ., 2019), and thus the authors designate the characteristics of lower lip of the new species described here (Figure 1a) comparing it to Rhadinoloricaria species (Figure 1b).…”

“…Scheme representing the buccal ornamentation of (a) Rhadinoloricaria papillosa (MZUSP uncat., Rhadinoloricaria papillosa , holotype) and (b) Rhadinoloricaria bahuaja (MUSM9916, holotype, Provenzano‐Rizzi and Barriga‐Salazar (2020) edit.). 1, maxillary barbel; 2, smooth barbelets; 3, elongated smooth papillae; 4, barbelets with lateral branches; 5, short papillae…”

“…The most recent study of subfamily Loricariinae (Londoño‐Burbano & Reis, 2021) placed six genera in the Pseudohemiodon group, including Dentectus , Reganella , Crossoloricaria , Planiloricaria , Pseudohemiodon and Rhadinoloricaria , based on morphological and molecular characters. About the last genus, Provenzano‐Rizzi and Barriga‐Salazar (2020) described a new species of Rhadinoloricaria from Ecuador, and from a comparative morphological analysis, the authors suggested the revalidation of Apistoloricaria , including Apistoloricaria condei , Apistoloricaria laani , Apistoloricaria listrorhinos and Apistoloricaria ommation , and suggested that the generic allocation of Rhadinoloricaria bahuaja and Rhadinoloricaria rhami is uncertain.…”