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Description and phylogenetic position of a new species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from the Jamanxim River basin

Abstract

In this study, a new species of Rhyacoglanis is described from the Jamanxim River basin, Tapajós River basin. The new species differs from congeners based on the combination of the following diagnostic characters: two oblique dark bands formed by an agglomerate of melanophores on the predorsal region; dorsal confluence between the dark subdorsal and subadipose bands in large juveniles and adults; ventral confluence between the dark subadipose and caudal peduncle bands; body without conspicuous dark brown spots; complete dark band on caudal peduncle; body with three dark bands; a thin dark caudal-fin band; pectoral-fin spine with anterior serrae distributed along the entire margin; the posterior tip of the post-cleithral process reaching vertical through the base of the dorsal-fin spine; and hypural 5 free of hypural 3 and 4 and pointed caudal-fin lobes. Additionally, our molecular phylogenetic results using ultraconserved elements (UCEs) corroborate the new species as Rhyacoglanis and sister to an undescribed species of Rhyacoglanis from the Xingu River basin. Moreover, as pointed out in previous studies, we confirm Cruciglanis as a sister group to Pseudopimelodus plus Rhyacoglanis.

Keywords:
Amazon basin; Bumblebee catfishes; Phylogenomic; South America region; Pseudopimelodinae

Resumo

Neste estudo, uma nova espécie de Rhyacoglanis é descrita para a bacia do rio Jamanxim, bacia do rio Tapajós. A nova espécie difere de congêneres com base na combinação dos seguintes caracteres diagnósticos: duas faixas escuras oblíquas formadas por um aglomerado de melanóforos na região predorsal, confluência dorsal entre as faixas subdorsais escuras e subadiposas em adultos grandes, confluência ventral entre as faixas subadiposas escuras e do pedúnculo caudal em adultos grandes, corpo sem manchas escuras proeminentes de cor marrom, faixa escura completa no pedúnculo caudal, corpo com três faixas escuras e uma fina faixa escura na nadadeira caudal, espinho da nadadeira peitoral com serrilhas anteriores distribuídas ao longo de toda a margem, extremidade posterior do processo pós-cleitral atingindo verticalmente a base do espinho da nadadeira dorsal, hipural 5 livre dos hipurais 3 e 4 e lobos da nadadeira caudal pontiagudos. Adicionalmente, nossos resultados filogenéticos moleculares utilizando elementos ultraconservados (UCEs) corroboram a nova espécie como Rhyacoglanis é irmã de uma espécie não descrita de Rhyacoglanis da bacia do rio Xingu. Além disso, como apontado em estudos anteriores, confirmamos que Cruciglanis é um grupo irmão de Pseudopimelodus mais Rhyacoglanis.

Palavras-chave:
América do Sul; Bacia Amazônica; Bagrinho-abelha; Filogenômica; Pseudopimelodinae

INTRODUCTION

Pseudopimelodidae, a Neotropical catfish family, is characterized by a wide mouth; small eyes without a free orbital margin; pectoral spine serrated anteriorly and posteriorly; and short barbels (Shibatta, 1998Shibatta OA. Sistemática e evolução da família Pseudopimelodidae (Ostariophysi, Siluriformes), com a revisão taxonômica do gênero Pseudopimelodus. [PhD Thesis]. São Carlos: Universidade Federal de São Carlos; 1998., 2003Shibatta OA. Family Pseudopimelodidae. In: Reis RE, Kullander SO, Ferraris CJ, Jr., editors.Checklist of the freshwater fishes of South America. Porto Alegre: Edipucrs; 2003. p.331–32.). Recent phylogenetic studies have recovered the monophyly of Pseudopimelodidae (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Rangel-Mendrano et al., 2021Rangel-Medrano JD, Ortega-Lara A, Márquez EJ. Ancient genetic divergence in bumblebee catfish of the genus Pseudopimelodus (Pseudopimelodidae: Siluriformes) from northwestern South America. PeerJ. 2020; 8:e9028. https://doi.org/10.7717/peerj.9028
https://doi.org/10.7717/peerj.9028...
; Silva et al., 2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
) and classified this group into two subfamilies (Silva et al., 2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
): Batrochoglaninae, composed by the genera Lophiosilurus Steindachner, 1876 (= Cephalosilurus Haseman, 1911), Microglanis Eigenmann, 1912, Batrochoglanis Gill, 1858, and Pseudopimelodinae, composed by Cruciglanis Ortega-Lara & Lehmann, 2006, Pseudopimelodus Bleeker, 1858, and RhyacoglanisShibatta & Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
.

Rhyacoglanis is a rheophilic genus of Pseudopimelodidae, living in rapids and other swift-flowing waters associated with rock bottoms. The species are distributed across Venezuela, Ecuador, Bolivia, and Brazil along Orinoco, Amazonas, and Paraná-Paraguay river basins (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Shibatta et al., 2021Shibatta OA, Rocha MS, Oliveira RR. New species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from rio Tocantins basin, northern Brazil. Neotrop Ichthyol. 2021; 19(4):e210083. https://doi.org/10.1590/1982-0224-2021-0083
https://doi.org/10.1590/1982-0224-2021-...
). The genus is distinguished from all other pseudopimelodids by three synapomorphies: a light blotch on the cheek, a connection between the middle of the dark caudal-fin stripe and the dark caudal peduncle pigmentation, and 30–35 total vertebrae (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
).

Currently, the genus has eight valid species: RhyacoglanisannulatusShibatta & Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
from Orinoco River basin, R. epiblepsisShibatta & Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
from Madeira River basin, R.paranensisShibatta & Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
from Paraná River basin, R. pulcher (Boulenger, 1887Boulenger GA. An account of the fishes collected by Mr. C. Buckley in eastern Ecuador. Proc Zool Soc Lond. 1887; 274–83) from western Amazonian basin, R. rapppydanielae Shibatta, Rocha & Oliveira, 2021 from the lower Tocantins River basin, R. seminigerShibatta & Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
from Juruena River, Tapajós basin, R. variiShibatta & Souza-Shibatta, 2023Shibatta OA, Souza-Shibatta L. New species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from the upper rio Tocantins basin. Neotrop Ichthyol. 2023; 21(1):e220075. https://doi.org/10.1590/1982-0224-2022-0075
https://doi.org/10.1590/1982-0224-2022-...
from the upper Tocantins basin and R. variolosus (Miranda Ribeiro, 1914Miranda Ribeiro A. Pimelodidae, Trachycorystidae, Cetopsidae, Bunocephalidae, Auchenipteridae, e Hypophthalmidae; Rio de Janeiro: Comissão de Linhas Telegraphicas Estrategicas de Matto-Grosso ao Amazonas. 1914; 5:1–13.) from Taquary River, Paraguay basin (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Shibatta et al., 2021Shibatta OA, Rocha MS, Oliveira RR. New species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from rio Tocantins basin, northern Brazil. Neotrop Ichthyol. 2021; 19(4):e210083. https://doi.org/10.1590/1982-0224-2021-0083
https://doi.org/10.1590/1982-0224-2021-...
).

Phylogenetic studies have corroborated the monophyly of Rhyacoglanis (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Silva et al., 2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
). Based on morphology, the hypothesis proposed by Shibatta, Vari (2017)Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
recovered R. paranensis sister to all other remaining Rhyacoglanis species that diverged into two sister clades, one composed of R. epiblepsis and R. annulatus, and the other with R. seminiger and R. pulcher.Alternatively, in the hypothesis based on molecular data (Silva et al., 2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
), R. pulcher is the sister group of the other species of Rhyacoglanis, forming a clade where R. paranensis is the sister to R. seminiger plus an undescribed species of Rhyacoglanis from Xingu River basin. In a recent expedition in the Jamanxim River, a new Amazonian Rhyacoglanis species was discovered and described here.

MATERIAL AND METHODS

Molecular analysis. DNA extraction and sequencing were followed Silva et al. (2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
) in this study. Sequences of the new species of Rhyacoglanis, Pseudopimelodus bufonius (Valenciennes, 1840), and P. charus (Valenciennes, 1840) were added to the data matrix Silva et al. (2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
) (Tab. S1), which contained 33 terminal taxa of Pseudopimelodidae and 18 related taxa.

After sequencing, adapter contamination, low-quality bases, and sequences containing ambiguous base calls were trimmed using the Illumiprocessor software pipeline developed by Faircloth et al. (2013)Faircloth BC, Sorenson L, Santini F, Alfaro ME. A phylogenomic perspective on the radiation of ray-finned fishes based upon targeted sequencing of ultraconserved elements (UCEs). PLoS ONE. 2013; 8(6):e65923. https://doi.org/10.1371/journal.pone.0065923
https://doi.org/10.1371/journal.pone.00...
. After trimming, we assembled Illumina reads into contigs on a species-by-species basis using the Velvet pipeline (Zerbino, Birney, 2008Zerbino DR, Birney E. Velvet: Algorithms for de novo short read assembly using de Bruijn graphs. Genome Res. 2008; 18:821–29. https://doi.org/10.1101/gr.074492.107
https://doi.org/10.1101/gr.074492.107...
). We then used a custom Python program (match_contigs_to_probes.py) implemented in PHYLUCE (Faircloth, 2016Faircloth BC. PHYLUCE is a software package for the analysis of conserved genomic loci. Bioinformatics. 2016, 32(5):786–88. https://doi.org/10.1093/bioinformatics/btv646
https://doi.org/10.1093/bioinformatics/...
), integrating LASTZ (Harris, 2007Harris RS. Improved pairwise alignment of genomic DNA. PhD Thesis. Pennsylvania: State University The Pennsylvania State University; 2007.Guidelines for using the IUCN Red List categories and criteria. Version 15.1 Internet. Gland; 2023. Available from: https://www.iucnredlist.org/resources/redlistguidelines
https://www.iucnredlist.org/resources/r...
) to align species-specific contigs to the probeUCE set. This last program creates a relational dataset of matches to UCEs loci by taxon. We then used the get_match_counts.py program (also included in PHYLUCE) to query the database and generate fasta files for UCE loci identified across all taxa. A custom Python program (seqcap_align_2.py) was then used to align contigs using the MUSCLE algorithm (Robert, 2004Robert CE. MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Res. 2004; 32(5):1792–97. https://doi.org/10.1093/nar/gkh340
https://doi.org/10.1093/nar/gkh340...
) and to perform edge trimmings (i.e., cutting edges of each alignment, eliminating highly variable and saturated regions).

We analyzed the Pseudopimelodidae dataset using maximum likelihood (ML; RAxML v8; Stamatakis, 2014Stamatakis A. RAxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics. 2014; 30(9):1312–13. https://doi.org/10.1093/bioinformatics/btu033
https://doi.org/10.1093/bioinformatics/...
). For this analysis, we used the Partition-UCE (Tagliacolo, Lanfear, 2018Tagliacollo VA, Lanfear R. Estimating improved partitioning schemes for UltraConserved Elements (UCEs). Mol Biol Evol. 2018; 35(7):1798–811. https://doi.org/10.1093/molbev/msy069
https://doi.org/10.1093/molbev/msy069...
) and performed model selection in PartitionFinder (Lanfear et al., 2012Lanfear R, Calcott B, Ho SYW, Guindon S. PartitionFinder: Combined selection of partitioning schemes and substitution models for phylogenetic analyses. Mol Biol Evol. 2012; 29(6):1695–701. https://doi.org/10.1093/molbev/mss020
https://doi.org/10.1093/molbev/mss020...
). Ten alternative runs using the GTRGAMMA model and distinct parsimony-starting trees were performed to find the best ML tree. Pseudo-replicates applied the autoMRE function for the extended majority-rule consensus tree criterion available in RAxML v8 (Stamatakis, 2014Stamatakis A. RAxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics. 2014; 30(9):1312–13. https://doi.org/10.1093/bioinformatics/btu033
https://doi.org/10.1093/bioinformatics/...
) to assess bootstrap support for branches. This option allows tests for bootstrap convergence, determining if pseudo-replicates are getting stable support values (Pattengale et al., 2010Pattengale ND, Alipour M, Bininda-Emonds ORP, Moret BME, Stamatakis A. How many bootstrap replicates are necessary? In: Annual international conference on research in computational molecular biology. Springer, Berlin: Heidelberg; 2009. p.184–200. Available from: https://link.springer.com/chapter/10.1007/978-3-642-02008-7_13
https://link.springer.com/chapter/10.10...
).

Morphological analysis. Morphological analysis was obtained with digital calipers to the nearest 0.1 mm, measuring variables point to point, following measurements proposed in Shibatta, Vari (2017)Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
. The second ray of the dorsal fin and the first ray of the pectoral fin, which were modified into spines, were included in counts as “I” and the first unbranched pelvic, anal, and caudal-fin rays as “i”. Type series were deposited at MZUSP (Museu de Zoologia, Universidade de São Paulo, São Paulo), MZUEL (Museu de Zoologia, Universidade Estadual de Londrina, Londrina), and LBP (Laboratório de Biologia e Genética de Peixes, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Botucatu). Head laterosensory pores were identified, according to Shibatta (2019)Lanfear R, Calcott B, Ho SYW, Guindon S. PartitionFinder: Combined selection of partitioning schemes and substitution models for phylogenetic analyses. Mol Biol Evol. 2012; 29(6):1695–701. https://doi.org/10.1093/molbev/mss020
https://doi.org/10.1093/molbev/mss020...
. For osteological counts, we stained and cleared one specimen following the procedures proposed by Taylor, Van Dyke (1985)Taylor WR, Van Dyke GC. Revised procedures for staining and clearing small fishes and other vertebrates for bone and cartilage study. Cybium. 1985; 9(2):107–19. Available from: https://sfi-cybium.fr/en/node/2423
https://sfi-cybium.fr/en/node/2423...
, and the bones’ nomenclature followed Shibatta (2019)Shibatta OA. New species of bumblebee catfish of the genus Batrochoglanis Gill, 1858 (Siluriformes: Pseudopimelodidae) from the Aripuanã River basin. Zootaxa. 2019; 4674(2):243–63. https://doi.org/10.11646/zootaxa.4674.2.6
https://doi.org/10.11646/zootaxa.4674.2...
. The abbreviation “eth” was assigned to specimens preserved in ethanol, while “C&S” was used to denote the cleared and stained specimen.

RESULTS

Rhyacoglanis beninei, new species

urn:lsid:zoobank.org:act:66E55031-BDEF-47EA-B578-4F4661A03190

(Figs. 14; Tab. 1)

Holotype. MZUSP 127014, 59.1 mm SL, Brazil, Pará State, córrego Jussara, tributary of Jamanxim River, municipally of Novo Progresso, Tapajós River basin, 07°21’08”S 55°17’45”W, 20 Aug 2022, G. S. C. Silva & T. C. Faria.

Paratypes. All from the same locality of holotype. LBP 25081, 5, 26.7–43.7 mm SL, 22 Sep 2017, A. C. Dias, C. S. Souza, C. Souto, N. Flausino Jr. & R. Devidé. LBP 32145, 8, 22.7–50.2 mm SL, the largest specimen was C&S, MZUEL 23049, 4, 29.4–42.6 mm SL, 20 Aug 2022, G. S. C. Silva & T. C. Faria. LBP 32163, 3, 27.0–47.9 mm SL, 22 Aug 2022, G. S. C. Silva & T. C. Faria.

Diagnosis.Rhyacoglanis beninei can be diagnosed from all congeners by two oblique dorsal dark brown bars on the predorsal region (Fig. 2) (vs. absent). Additionally, R. beninei is distinguished from some congeners by having a dorsal confluence between the dark subdorsal and subadipose bands in large juveniles and adults (> 28 mm SL) (vs. lack dorsal confluence in R. paranensis, R. annulatus, R. varii, and R. rapppydanielae); ventral confluence between the dark subadipose and caudal peduncle bands (vs. lack ventral confluence in R. annulatus, R. epiblepsis, R. paranensis, R. seminiger, and R. rapppydanielae); body without conspicuous dark brown spots (vs. conspicuous dark brown spots in R. epiblepsis and R. rapppydanielae); complete dark band on caudal peduncle (vs. caudal peduncle-band with a unpigmented central region in R. annulatus); body with three dark bands (vs. two dark bands in R. seminiger); a thin dark caudal-fin bands (vs. large caudal-fin bands in R. paranensis and R. epiblepsis); pectoral-fin spine with anterior serrae distributed along the entire margin (restricted to the proximal half in R. pulcher and R. seminiger); posterior tip of the post-cleithral process reaching vertical through the base of the dorsal-fin spine (vs. not reaching in R. epiblepsis and R. rapppydanielae); hypural 5 free of hypural 3 and 4 (vs. hypurals 4 and 5 fused in R. rapppydanielae); pointed caudal-fin lobes (vs. rounded lobes in R. epiblepsis).

FIGURE 1 |
Rhyacoglanis beninei, holotype, MZUSP 127014, 59.1 mm SL, from córrego Jussara, an affluent of Jamanxim River, Tapajós River basin. Scale bar = 10 mm.

Description. Morphometric data from Rhyacoglanis beninei is available in Tab. 1. In lateral view, straight profile of body from snout tip to dorsal-fin origin followed by a straight profile from dorsal-fin base to caudal-fin insertion. Body ventral surface slightly convex from snout tip to opercular opening region, straight to slightly concave from head posterior end to anal-fin insertion, and straight-angled upward on caudal peduncle.

TABLE 1 |
Morphometric data of Rhyacoglanis beninei. N = 21 specimens, including the holotype.

Head depressed with numerous well-developed unculiferous tubercles. Head dorsal profile in a rounded trapezoidal shape, with most anterior region narrower than posterior region. Wide mouth, larger than distance between posterior nostrils. Posterior nostrils opening wider than anterior nostrils. Thick lips with lateral portion extended posteriorly. Dentigerous plates on premaxilla and dentary. Eyes small, covered by skin. Opercular opening covered by a well-developed membrane. Maxillary barbels reaching first branched pectoral-fin ray base. Inner mental barbel small, not reaching isthmus, and outer mental barbel reaching first pectoral-fin ray base. Head laterosensory system bearing conspicuous pores, including six infraorbital, five supraorbital, nine premaxillaries, one premaxillary-postorbital, and one postorbital.

First dorsal-fin ray forming spine locking mechanism. Second dorsal-fin ray modified in a spine, smooth on anterior margin and serrated on posterior margin. Adipose-fin base broad, generally larger than dorsal-fin base. Pectoral and pelvic fins roughly triangular, distal margin larger than base. First pectoral-fin ray as spine with retrorse serrations on anterior and posterior margin (Fig. 3). Pectoral, pelvic, anal, and adipose fins distal margins round. Caudal fin bifurcated with acute dorsal and ventral lobes. Dorsal-fin rays II,6* (1 C&S, 11 eth); pectoral-fin rays I,6* (1 C&S, 13 eth); pelvic-fin rays i,5* (1 C&S, 13 eth); anal-fin rays iii,5 (2 eth), iv,6 (1 C&S) or iii,6 (5), iii,7* (1); caudal-fin rays i,6,8,i* (1 C&S, 11 eth) or i,5,7,i (1 eth). Dorsal procurrent caudal-fin rays 16 (1 C&S), ventral procurrent caudal-fin rays 12 (1 C&S). Branchiostegal rays 8 (1 C&S). Total vertebrae 33 (1 C&S). Ribs 9 (1 C&S).

FIGURE 2 |
Pigmentation of oblique dark bars in the predorsal region of Rhyacoglanis beninei. A. MZUEL 23049, 29.6 mm SL; B. LBP 32145, 32.9 mm SL; C. LBP 32145, 37.3 mm SL; D. MZUEL 23049, 42.6 mm SL; E. LBP 32145, 50.2 mm SL. Scale bars = 10 mm.
FIGURE 3 |
Rhyacoglanis beninei pectoral-fin spine, paratype, LBP 32145, 50.2 mm SL.

Coloration in alcohol. Ground color yellowish to brownish, with three conspicuous dark brown bands on body (Figs. 1, 2, 5). The first dark band under dorsal fin (subdorsal), the second under adipose fin (subadipose), and the third posterior adipose fin, extending to the caudal-fin base. Subadipose and caudal peduncle bands surrounding body; subdorsal band open in ventral region; all bands with variable connections pattern on lateral side (Fig. 5) in individuals of different SL, sometimes not present in small juveniles (< 28 mm SL – Fig. 5C). Two oblique dark brown bands on predorsal region in dorsal view, each beginning just laterally to parieto-supraoccipital process, continuing towards posterior cleithral process (Fig. 2). Pectoral and pelvic fins hyaline with middle dark brown stripe and numerous melanophores dispersed. Anal-fin hyaline with middle dark brown stripe and numerous melanophores spread; fin base with dark brown band and first unbranched ray base with clear dot. Caudal fin hyaline, dorsal, and ventral lobes with middle dark brown stripe and numerous melanophores dispersed. Dorsal-fin dark brown with numerous melanophores on hyaline margin. Adipose fin dark brown, clear dot on anterior base portion with numerous melanophores. Head grayish with lighter region on cheek.

Coloration in life. Same as alcohol-preserved specimens, but the light regions brighter, ranging from yellowish to brownish (Fig. 4C).

Geographical distribution.Rhyacoglanisbeninei is known only from the type locality in the Jamanxim River, Tapajós River basin, Brazil (Fig. 6). The new species was collected in fast-flowing currents of Córrego Jussara, characterized by clear water and the bottom with rocks and gravels (Fig. 4).

Etymology.Rhyacoglanis beninei is named in honor of Ricardo Cardoso Benine, Professor at Universidade Estadual Paulista “Júlio de Mesquita Filho”, in recognition of his dedication and remarkable contributions to the knowledge of Neotropical freshwater fishes.

FIGURE 4 |
A. Habitat of Rhyacoglanis beninei in córrego Jussara, 07°21’08”S 55°17’45”W; B. A rock where specimens of R. beninei were associated; C. Paratype of R. beninei just after capture. Photo: Gabriel S. Costa e Silva.
FIGURE 5 |
Variation pattern of dark body bands in Rhyacoglanis beninei. A. MZUEL 23049, 42.6 mm SL; B. LBP 32145, 29.8 mm SL; C. LBP 32163, 27.0 mm SL; D. LBP 32163, 42.9 mm SL. Scale bars = 10 mm.
FIGURE 6 |
The type locality of Rhyacoglanis beninei in córrego Jussara, 07°21’08”S 55°17’45”W (yellow star), Tapajós River basin.

Conservation status. All specimens of Rhyacoglanis beninei were collected at only one sample site. However, several specimens were collected at the type locality, indicating a common occurrence and no apparent threat of extinction. According to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2023), we propose classifying Rhyacoglanis beninei as category Least Concern (LC).

Phylogeny. Sequencing and data filtering yielded a 70% complete matrix with 1082 loci and 385,841 bp. Results support the monophyly of Pseudopimelodidae and the monophyly of Pseudopimelodinae and Batrochoglaninae subfamilies. Inside Pseudopimelodinae, Cruciglanis is the sister to Pseudopimelodus + Rhyacoglanis, as supported by Silva et al. (2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
). Internally to Pseudopimelodus, our analysis found P. bufonius sister to P. charus + P. mangurus (Valenciennes, 1835). Rhyacoglanis also recovered as a monophyletic group, where R. pulcher was recovered as sister to a clade composed of two subclades, the first composed of R. semininger + R. paranensis and the second composed of R. beninei + Rhyacoglanis n. sp. “Xingu” (Fig. 7).

FIGURE 7 |
Maximum likelihood tree of Pseudopimelodidae on the 70% complete matrix (1082 loci, 385,841 bp). Nodes without symbols represent 100% support from 1000 bootstrap pseudo-replicates; nodal support between 99% and 75% denote by black circles; gray nodes indicate support between 75% and 50%.

DISCUSSION

Among all valid species of Rhyacoglanis, R. beninei is unique by possessing two conspicuous oblique dark bars on the predorsal portion of the trunk (Fig. 2). Rhyacoglanis n. sp. “Xingu” and R. seminiger also have a dark blotch in the same region. However, the dark chromatophores on the predorsal region form a paired rounded blotch in those species. In R. paranensis, R. epiblepsis, R. pulcher, and R. varii this blotch is absent. Even though these dark bars persist throughout the R. beninei development stage of life, in the smaller specimens (< 40 mm SL), this mark is thinner and more conspicuous when compared to larger individuals, which present thicker and more diffuse bars (Fig. 2). According to some Pseudopimelodidae phylogenetic analyses (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Shibatta et al., 2021Shibatta OA, Rocha MS, Oliveira RR. New species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from rio Tocantins basin, northern Brazil. Neotrop Ichthyol. 2021; 19(4):e210083. https://doi.org/10.1590/1982-0224-2021-0083
https://doi.org/10.1590/1982-0224-2021-...
; this study), the occurrence of such marks in the predorsal region is a synapomorphy of Pseudopimelodinae, and their absence may have occurred independently in the Rhyacoglanis species.

Another conspicuous diagnostic feature is the connections between the three vertical dark brown bands (subdorsal, subadipose, and caudal peduncle). In large juveniles and adults (> 28 mm SL), the subdorsal and subadipose bands and the subadipose and caudal peduncle bands are frequently united (dorsally and ventrally, respectively) by a dark stripe (Figs. 1, 5A, B, D). In contrast, in the small individual, the three vertical bands are entirely separated (Figs. 4C, 5C) by yellowish regions and without dark brown spots.

Our data confirm the monophyly of Rhyacoglanis following previous phylogenetic studies (Shibatta, Vari, 2017Shibatta OA, Vari RP. A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae). Neotrop Ichthyol. 2017; 15(2):e160132. https://doi.org/10.1590/1982-0224-20160132
https://doi.org/10.1590/1982-0224-20160...
; Silva et al., 2021Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
). Furthermore, our results show R. pulcher as a sister to a clade containing the remaining species of Rhyacoglanis, composed of amazon species R. seminiger, Rhyacoglanis n. sp. “Xingu”, R. beninei, and R. paranensis from the upper Paraná River basin. Curiously, R. beninei (Jamanxim River) is not a sister to R. seminiger (Arinos River), another species described from the Tapajós River basin, but a sister to an undescribed species of Rhyacoglanis from the Xingu River basin (Fig. 7). This relationship pattern suggests a historical connection between the headwaters of the western portion of the Xingu River basin and the headwater of the Jamanxim River. Similarly, Shibatta, Souza-Shibatta (2023) observed a close phylogenetic relationship with R. varii from upper Tocantins and R. paranensis from upper Paraná. Therefore, both studies show the headwaters capturing influencing the distribution of Rhyacoglanis species.

We also re-build a phylogeny of Pseudopimelodus, using the UCEs matrix dataset published by Silva et al. (2021)Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
, adding Pseudopimelodus charus and P. bufonius. In Silva et al. (2021)Silva GSC, Melo BF, Roxo FF, Ochoa LE, Shibatta OA, Sabaj MH, Oliveira C. Phylogenomics of the bumblebee catfishes (Siluriformes: Pseudopimelodidae) using ultraconserved elements. J Zool Syst Evol Res. 2021; 59(8):1662–72. https://doi.org/10.1111/jzs.12513
https://doi.org/10.1111/jzs.12513...
, the monophyly of Pseudopimelodus was impossible to test since only one species (P. mangurus) was included in that phylogeny. Rangel-Mendrano et al. (2021)Rangel-Medrano JD, Ortega-Lara A, Márquez EJ. Ancient genetic divergence in bumblebee catfish of the genus Pseudopimelodus (Pseudopimelodidae: Siluriformes) from northwestern South America. PeerJ. 2020; 8:e9028. https://doi.org/10.7717/peerj.9028
https://doi.org/10.7717/peerj.9028...
, in a genetic analysis using a multi-locus approach, supported the monophyly of Pseudopimelodus, with P. charus (from the São Francisco basin) sister to P. bufonius (Amazon basin) + P. mangurus (Paraná basin). Our result also supports the monophyly of Pseudopimelodus but places P. bufonius sister to P. charus plus P. mangurus. This arrangement is congruent with other molecular phylogenetic studies, under which monophyletic components from the upper Paraná and São Francisco river basins have been recognized as sister group (Montoya-Burgos, 2003Montoya-Burgos JI. Historical biogeography of the catfish genus Hypostomus (Siluriformes: Loricariidae), with implications on the diversification of Neotropical ichthyofauna. Mol Ecol. 2003; 12(7):1855–67. https://doi.org/10.1046/j.1365-294X.2003.01857.x
https://doi.org/10.1046/j.1365-294X.200...
; Roxo et al., 2014Roxo FF, Albert JS, Silva GS, Zawadzki CH, Foresti F, Oliveira C. Molecular phylogeny and biogeographic history of the armored Neotropical catfish subfamilies Hypoptopomatinae, Neoplecostominae and Otothyrinae (Siluriformes: Loricariidae). PLoS ONE. 2014; 9(8):e105564. https://doi.org/10.1371/journal.pone.0105564
https://doi.org/10.1371/journal.pone.01...
; Ochoa et al., 2020Ochoa LE, Datovo A, DoNascimiento C, Roxo FF, Sabaj Pérez MH, Chang J, Melo BF, Silva GSC, Foresti F, Alfaro M, Oliveira C. Phylogenomic analysis of trichomycterid catfishes (Teleostei: Siluriformes) inferred from ultraconserved elements. Sci Rep. 2020; 10(2697). https://doi.org/10.1038/s41598-020-59519-w
https://doi.org/10.1038/s41598-020-5951...
).

Comparative material examined. All specimens of comparative material are deposited in the LBP collection. Brazil. Rhyacoglanis paranensis: LBP 11716, 9, 30.9–45.7 mm SL, Paranaíba River, Minas Gerais State; LBP 11743, 1, 29.8 mm SL, Paranaíba River, Minas Gerais State; LBP 11740, 2, 43.4–43.7 mm SL, Paranaíba River, Minas Gerais State; LBP 30034, 4, 52.5–85.6 mm SL, Jaguari River, São Paulo State; LBP 17708, 4, 27.4– 34.4 mm SL, Mogi-Guaçu River, São Paulo State; LBP 28747, 6, 28.5–35.0 mm SL, Mogi-Guaçu River, São Paulo State; LBP 18831, 4, 33.7–36.2 mm SL, Sapucaí-Mirim River, São Paulo State; LBP 8083, 3, 47.6–62.7 mm SL, Ivaí River, Paraná State. Rhyacoglanis seminiger: LBP 13260, 4, 45.2–61.4 mm SL, Alegre Stream, Mato Grosso State. Rhyacoglanis variolosus:LBP32030, 5, 27.8–41.3 mm SL, Jauru River, Mato Grosso do Sul State. Rhyacoglanis sp. n. ‘Xingu’:LBP 15883, 2, 52.1–57.3 mm SL, Coluene River, Mato Grosso State; LBP 15906, 1, 67.6 mm SL, Coronel Vanick River, Mato Grosso State. Rhyacoglanis cf. pulcher: LBP 25390, 1, 37.4 mm SL, Pimenta Bueno River, Rondônia State. Rhyacoglanis sp.: LBP 1567, 2, 22.2–32.6 mm SL, Araguaia River, Mato Grosso State.

ACKNOWLEDGEMENTS

Thanks to A. C. Dias, C. S. Souza, C. Souto, N. Flausino Jr., R. Devidé, and T. Faria for their help during field expeditions. Thanks also to Bruno F. Morales for helping with the map construction. We also thank the research support from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (JLCR), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, proc. #307951/2021–9 to OAS and proc. 306054/2006–0 to CO), and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) grant #2020/13433–6 (CO), grants #2021/12979–8 and #2022/13025–0 (GSCS).

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ADDITIONAL NOTES

  • HOW TO CITE THIS ARTICLE

    Crispim-Rodrigues JL, Silva GSC, Shibatta OA, Kuranaka M, Oliveira C. Description and phylogenetic position of a new species of Rhyacoglanis (Siluriformes: Pseudopimelodidae) from the Jamanxim River basin. Neotrop Ichthyol. 2023; 21(3):e230051. https://doi.org/10.1590/1982-0224-2023-0051

Edited-by

Carlos DoNascimiento

Publication Dates

  • Publication in this collection
    21 Aug 2023
  • Date of issue
    2023

History

  • Received
    13 May 2023
  • Accepted
    13 July 2023
Sociedade Brasileira de Ictiologia Neotropical Ichthyology, Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura, Universidade Estadual de Maringá., Av. Colombo, 5790, 87020-900, Phone number: +55 44-3011-4632 - Maringá - PR - Brazil
E-mail: neoichth@nupelia.uem.br