The type specimens of Trichomycterus alternatus (Eigenmann, 1917) and Trichomycterus zonatus (Eigenmann, 1918), with elements for future revisionary work (Teleostei: Siluriformes: Trichomycteridae)

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A new species of Trichomycterus is described from rocky and psammic sectors near the main channel of the middle and upper Rio Doce basin in Southeastern Brazil.Trichomycterus astromycterus n. sp., is distinguished from all congeners by a number of autapomorphic characters, such as the distally expanded maxilla; the short and thick mesethmoid cornua; and the elongated anterior process of the vomer. Additional characters (short barbels, large head, 33 vertebrae, ii+8 or ii+9 dorsal-fin rays, nine dorsal-fin pterygiophores, markedly enlarged lips, narrow caudal peduncle, bilobed caudal fin with the lower lobe longer than the upper one) also distinguish the new species from all its congeners in Southeastern Brazil and from most congeners anywhere. Examination of internal anatomy reveals that T. astromycterus shares some intriguing characteristics with the austral genus Bullockia Arratia et al., 1978. However, the phylogenetic significance of such similarities is still uncertain and will require further comparative study. For this reason, the new species is provisionally included in the all-encompassing genus Trichomycterus. An osteological description is presented on the basis of CT-scan imaging and cleared and stained specimens. K E Y W O R D S

Section: Introductionmentioning

confidence: 99%

A new species of Trichomycterus Valenciennes 1832 (Trichomycteridae: Siluriformes) from the Rio Doce drainage with remarkable similarities with Bullockia and a CT‐scan survey

Reis

Pinna

Pessali

2019

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“…In all examined species of Trichomycterus , the epioccipital is a flat bone with smooth and rounded contours. The same is true for the few species where this cranial element has been described or illustrated ( T. alternatus (Eigenmann 1917) in Reis & de Pinna, : fig. 4, p. 108; T. areolatus , T. gracilis Valenciennes 1846, T. nigricans , T. punctulatus Valenciennes 1846, and T. rivulatus Valenciennes 1846 in Arratia, : figs.…”

Section: Discussionmentioning

confidence: 68%

A new troglomorphic species of Trichomycterus (Siluriformes: Trichomycteridae) from north‐eastern Colombia, with proposal of a new Trichomycterus subclade and remarks on some nominal species from Colombia

DoNascimiento

Prada-Pedreros

2020

Trichomycterus spectrum is described as a new species from the Alejo cave, drained by the Ranchería River basin, in La Guajira department, north‐eastern Colombia, and is the first troglomorphic species described from this region. The new species shows an advanced degree of troglomorphisms expressed as eyes absent, long barbels and body depigmented. Trichomycterus spectrum is diagnosed by the putatively autapomorphic presence of a posterior process at the anterolateral corner of the epioccipital, and is also recognized by the derived presence of a circular foramen on the neural spine of the complex vertebra and the following posterior vertebra, and by the apomorphic presence of a well‐developed coracoid bridge, distally expanded, and contacting or almost reaching the lateral margin of the cleithrum. The new species also shows the derived origin of the levator internus 4 on the dorsal surface of the posttemporo‐supracleithrum that supports Trichomycterinae monophyly. We also propose a monophyletic subgroup provisionally within Trichomycterus, here named the Trichomycterus taenia species group, which includes species distributed in cis‐ and trans‐Andean drainages in northern South America. The taxonomic status of several recently described nominal species from Colombia is discussed, with several synonymy proposals. Resumen Trichomycterus spectrum es descrito como una especie nueva de la cueva de Alejo, drenada por la cuenca del río Ranchería, en el departamento de La Guajira, noreste de Colombia, y es la primera especie troglomórfica descrita para esta región. La especie nueva exhibe un grado avanzado de troglomorfismos expresado como ojos ausentes, barbillas largas y cuerpo depigmentado. Trichomycterus spectrum es diagnósticado por la presencia putativamente autapomórfica de un proceso posterior en la esquina anterolateral del epióticoy es reconocido también por la presencia derivada de un foramen circular en la espina neural de la vértebra compleja y de la vértebra posterior siguiente, y por la presencia apomórfica de un puente coracoideo bien desarrollado, expandido distalmente y contactando o muy próximo al margen lateral del cleitro. La especie nueva también posee el origen derivado del levator internus 4 sobre la superficie dorsal del posttemporo‐supracleitro que soporta la monofilia de Trichomycterinae. También proponemos un subgrupo monofilético provisionalmente dentro de Trichomycterus, denominado aquí como el grupo de especies Trichomycterus taenia, el cual incluye especies distribuidas en cuencas cis y transandinas en el norte de Sudamérica. El estatus taxonómico de varias especies nominales recientemente descritas de Colombia es discutido, con varias propuestas de sinonimia.

“…Molecular results confirm the recent hypotheses by other authors (Donin, ; Reis & de Pinna, ) that Trichomycterus alternatus was equivocally identified as T. zonatus (= Cambeva zonata ) in collections as well as in the literature (Menezes et al , ; Oyakawa et al , ). Consequently, some putative occurring localities of C. zonata cited in the literature ( e.g ., Lima, ; Wosiacki & Oyakawa, ) are refuted and correspond to T. alternatus .…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, T. alternatus seems to have a wide distribution and found in several isolated drainages of south and southeast Brazil, extending from Paranaguá Bay tributaries to the Doce River basin(Donin, 2019). Other authors argued that T. alternatus is likely part of a species complex that may include other nominal species, needing an extensive revision(Lima, 2009, erroneously cited as F I G U R E 9 Colouration in live specimens from two ontogenetic stages of (a) Trichomycterus alternatus (UFRGS 24540, 57.2 and 40.9 mm L S , tributary of Guaraqueçaba River, Paranaguá Bay), and (b) Trichomycterus jacupiranga (UFRGS 24555, 44.8 mm L S and 35.1 mm L S , córrego do Queimado, Ribeira de Iguape River basin) Trichomycterus zonatus;Reis, 2018;Reis & de Pinna, 2019). In the samples of T. alternatus (see "Comparative Material Examined") analysed here, no diagnostic morphological differences were observed, and there is also little genetic structuration (seeSupporting Information Tables S3 and S4) when comparing samples from Paranaguá Bay tributaries, Ribeira de Iguape River and coastal rivers in the state of São Paulo.…”

mentioning

confidence: 99%

Taxonomical study of Trichomycterus (Siluriformes: Trichomycteridae) from the Ribeira de Iguape River basin reveals a new species recorded in the early 20th century

Donin

Ferrer

Carvalho

2020

A new species of Trichomycterus endemic to the Ribeira de Iguape River basin, southeastern Brazil, was studied based on morphological and molecular evidence. This species had an outer layer of coloration composed of scattered, round, black or dark‐brown spots smaller or equivalent in size to the circumference of the eye; eight pectoral‐fin rays; 28–29 opercular odontodes; 54–56 interopercular odontodes; and supraorbital line of the laterosensory system not interrupted, with pores s2 absent. Two other species of Trichomycterus from the Ribeira de Iguape River basin are recorded, and their taxonomic status is discussed: Trichomycterus alternatus and Trichomycterus jacupiranga were not differentiated using molecular analysis but may be consistently distinguished based on morphology. The phylogenetic relationships of the co‐occurring species, T. alternatus and Cambeva zonata, were inferred using mitochondrial data, reinforcing the taxonomic status of these recently revised species that have a complex taxonomy. In addition, a new combination for Trichomycterus taroba with its inclusion in the genus Cambeva is recommended.