An appraisal of the phylogenetic relationships of Hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae)

Abstract

The discovery of three new taxa of Hypoptotopomatini with ambiguous generic assignment prompted a reanalysis of the phylogenetic relationships of the tribe. The analysis focused on a data matrix of 56 terminals and 107 morphological characters comprising the three new taxa, most species of Hypoptopoma and Otocinclus, and all other species of the tribe. The 162 maximally parsimonious trees of 382 steps, consistency index of 0.41, and retention index of 0.83 were then summarized in a strict consensus tree. The results confirm the monophyly of the Hypoptopomatini, recover four genera as monophyletic (Acestridium, Hypoptopoma, Niobichthys, and Otocinclus), revealed Hypoptopoma and Oxyropsis to be non-monophyletic; and revealed two new genera within Hypoptopomatini. Additionally, Otocinclus was found to be sister to a group with all remaining genera of the tribe; Acestridium and Niobichthys were found to be sister to each other and that clade sister to a group formed by ((Leptotocinclus + Hypoptopoma [part]) + (Nannoxyropsis (Oxyropsis + Hypoptopoma [part]))). Based on this framework, changes to the classification and the taxonomy of the Hypoptopomatini are suggested and the new taxa are described.Keywords: Hypoptopomatinae, Morphology, New genera, Systematics, Taxonomy.A descoberta de três novos táxons pertencentes à Hypoptopomatini com designações genéricas incertas, levaram a uma nova análise das relações filogenéticas da tribo. A análise focou em uma matriz de dados formada por 56 terminais e 107 caracteres morfológicos incluindo os três novos táxons, a maioria das espécies de Hypoptopoma e Otocinclus, e todas as demais espécies da tribo. As 162 árvores maximamente parcimoniosas com 382 passos, índice de consistência 0.41 e índice de retenção 0.83 foram sumarizadas em um consenso estrito. O resultado obtido corrobora o monofiletismo de Hypoptopomatini, recupera quatro gêneros como grupos monofiléticos (Acestridium, Hypoptopoma, Niobichthys, e Otocinclus), aponta Hypoptopoma e Oxyropsis como grupos não-monofiléticos e revela dois novos gêneros pertencentes à Hypoptopomatini. Adicionalmente, Otocinclus foi encontrado como sendo grupo-irmão de um clado formado por todos os demais gêneros da tribo e Acestridium e Niobichthys formam um grupo-irmão mais relacionado a um clado formado por dois grupos monofiléticos ((Leptotocinclus + Hypoptopoma [parte]) + (Nannoxyropsis (Oxyropsis + Hypoptopoma [parte]))). Com base neste cenário, sugere-se mudanças na classificação e na taxonomia de Hypoptopomatini e os novos táxons são descritos.

Species delimitation in a range‐restricted group of cascudinhos (Loricariidae: Epactionotus) supports morphological and genetic differentiation across coastal rivers of southern Brazil

“…When analysing the species and populations of Epactionotus , all the diagnostic characters described by Reis and Schaefer (1998) added to the absence of the connecting bone, which is considered another independently derived diagnostic feature of Epactionotus (Calegari et al ., 2011; Delapieve et al ., 2017; Martins et al ., 2014; Rodriguez et al ., 2015), were observed here. Therefore, in spite of new information provided over the past 20 years, the combination of the diagnostic characters formerly given by Reis and Schaefer (1998) has proven to be useful.…”

“…Individuals were diagnosed as Epactionotus based on the absence of an expanded fleshy flap on the dorsal surface of the first pelvic‐fin ray of males, possession of accessory oral teeth and presence of two longitudinal light stripe markings on the dorsal surface of the head and trunk (Reis & Schaefer, 1998). Additional diagnostic osteological characters, such as the neural spine of the seventh vertebra contacting the unpaired predorsal plate anterior to the nuchal plate, dorsal‐fin proximal radial contacting the eighth vertebra and absence of the connecting bone (Calegari et al ., 2011; Delapieve et al ., 2017; Martins et al ., 2014; Reis & Schaefer, 1998; Rodriguez et al ., 2015), were checked in cleared and double‐stained specimens prepared according to a modification of the procedure described by Taylor and Van Dyke (1985).…”

“…Individuals were diagnosed as Epactionotus based on the absence of an expanded fleshy flap on the dorsal surface of the first pelvic-fin ray of males, possession of accessory oral teeth and presence of two longitudinal light stripe markings on the dorsal surface of the head and trunk (Reis & Schaefer, 1998). Additional diagnostic osteological characters, such as the neural spine of the seventh vertebra contacting the unpaired predorsal plate anterior to the nuchal plate, dorsal-fin proximal radial contacting the eighth vertebra and absence of the F I G U R E 2 Epactionotus bilineatus from Maquiné (MQ), MCP 19105, female, 30.6 mm standard length, Brazil, Rio Grande do Sul, Maquiné, Arroio do Ouro (29 39 0 58 00 S, 50 10 0 59 00 W) F I G U R E 3 Epactionotus bilineatus from Três Forquilhas (TF), MCP 28978, male, 34.3 mm standard length, Brazil, Rio Grande do Sul, Três Forquilhas, Arroio Japonês, (c. 29 32 0 S, 50 05 0 W) F I G U R E 4 Epactionotus itaimbezinho from Mampituba (MA), MCP 23683, male, 34.9 mm standard length, Brazil, Santa Catarina, Morrinhos do Sul, Rio Mangue (29 14 0 55 00 S, 49 55 0 30 00 W) F I G U R E 5 Epactionotus gracilis from Araranguá (AR), UFRGS 22945, male, 28.2 mm standard length, Brazil, Santa Catarina, Nova Veneza (28 35 0 02.2 00 S, 49 32 0 31.2 00 W) connecting bone (Calegari et al, 2011;Delapieve et al, 2017;Martins et al, 2014;Reis & Schaefer, 1998;Rodriguez et al, 2015), were checked in cleared and double-stained specimens prepared according to a modification of the procedure described by Taylor and Van Dyke (1985).…”

Parotocinclus nandae, a new distinctive colored catfish (Loricariidae: Hypoptopomatinae) from the upper Rio Paraguaçu, Bahia State, northeastern Brazil

“…The loricariid fishes of the subfamily Hypoptopomatinae, or small armored catfishes known as "cascudinhos" in Brazil, includes 32 valid genera and 247 species distributed throughout most of lowland tropical South America and generally found in shallow streams and typically associated with emergent and marginal macrophytes [1,2]. Parotocinclus Eigenmann & Eigenmann, 1889, one of the most species-rich genus of Hypoptopomatinae, includes 34 valid species with standard length ranging from 20 to 80 mm and distributed across cis-Andean South America from Colombia and Venezuela to northern Argentina [3][4][5][6][7].…”

Gross brain morphology of Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae): Comparative anatomy and phylogenetic implications

“…The proposed phylogenetic hypotheses (Calegari, 2010; Delapieve, Lehmann, & Reis, 2017; Gauger & Buckup, 2005; Lehmann, 2006; Martins et al., 2014; Ribeiro, Carvalho, & Melo, 2005; Roxo et al., 2014, 2019; Schaefer, 1991, 1998) diverge on the generic composition of the subfamily and on the relationships among its members. Although the recovery of the clade composed by Acestridium Haseman, 1911, Hypoptopoma , Leptotocinclus Delapieve, Lehmann & Reis, 2018, Nannoptopoma Schaefer, 1996, Nannoxyropsis Delapieve, Lehmann & Reis, 2018, Niobichthys Schaefer & Provenzano, 1998, Otocinclus, and Oxyropsis , and also of the clade Otothyris , Pseudotothyris Britski & Garavello, 1984, and Schizolecis Britski & Garavello, 1984, for example, appears to be a consensus, the position and/or intrageneric relationships of many genera, such as Microlepidogaster , Rhinolekos , Hisonotus , Otothyropsis Ribeiro, Carvalho & Melo, 2005, Parotocinclus , Epactionotus Reis and Schaefer, 1998, and Eurycheilichthys Reis & Schaefer, 1993, are still far from certain.…”