[Ichthyology • 2021] Redescription of the Guiana Shield Darter Species Characidium crandellii and C. declivirostre (Characiformes: Crenuchidae) with Descriptions of Two New Species: Characidium duplicatum & C. wangyapoik

Characidium crandellii Steindachner, 1915; C. declivirostre Steindachner, 1915; 

Characidium duplicatum & C. wangyapoik 

 Armbruster, Lujan & Bloom, 2021

 DOI: 10.1643/i2019299 

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Abstract  

Based on collections made in the western Guiana Shield over the last 21 years, Characidium crandellii and C. declivirostre are redescribed and two similar species are described from Guyana. These species all have enlarged paired fins with three to four rays thickened ventrally on the pectoral fin and two rays thickened on the pelvic fin. The species can be separated from all other Characidium and Melanocharacidium by having the venter unscaled from the isthmus to the pelvic origin. Characidium crandellii is found in the Essequibo and Takutu River systems and in an isolated population above Tencua Falls in the Ventuari River and the upper Paragua River (Orinoco River basin). Characidium declivirostre is found throughout the right-bank, shield tributaries of the Orinoco River system and in the upper Negro River. Characidium duplicatum, new species, appears to be rare but widely distributed in the Essequibo River system. Characidium wangyapoik, new species, is only known from the upper Ireng River, Branco River basin, along the border between Brazil and Guyana.

Characidium crandellii Steindachner, 1915

Characidium declivirostre Steindachner, 1915

Characidium duplicatum, new species

Distribution.—(Fig. 9) Found throughout the Essequibo River basin, but has been rarely encountered during our surveys. Most locations are in the lower Potaro and Kuribrong, but two localities are in the upper Essequibo upstream of the mouth of the Kuyuwini River.

Etymology.—Duplicatum is Latin for double and is a neuter adjective. In reference to the presence of two unbranched anal-fin rays.

 

Characidium wangyapoik, new species

Distribution.—(Fig. 9) Characidium wangyapoik is only known from the upper Ireng River basin (Amazon River) along the Brazil/Guyana border (known as the Rio Mau in Brazil). Specimens were collected from below Orinduik Falls to the upper falls on the Ireng and its equal tributary, the Sukwabi River, but not above the Uluk Tuwuk or Wotawanda falls of the upper Ireng and Sukwabi Rivers (see Lujan et al., 2020, for a more detailed map and description of this area).

Etymology.—Wangyapoik is the Patamona word for the species, and it is used as a noun in apposition. Wang means ‘honey' and yapoik means ‘seated,’ perhaps in reference to the yellowish color. The Patamona also refer to the species by the English common name of “fallsfish.”

Jonathan W. Armbruster, Nathan K. Lujan and Devin D. Bloom. 2021. Redescription of the Guiana Shield Darter Species Characidium crandellii and C. declivirostre (Crenuchidae) with Descriptions of Two New Species. Ichthyology & Herpetology. 109(1); 102-122. DOI: 10.1643/i2019299 

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[Ichthyology • 2020] Phylogeny and Biogeography of the Brazilian–Guiana Shield Endemic Corymbophanes Clade of Armoured Catfishes (Loricariidae)

Yaluwak primus Lujan, Armbruster & Werneke

in Lujan, Armbruster, Werneke, Teixeira & Lovejoy, 2020. 

DOI: 10.1093/zoolinnean/zlz090  

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Abstract

Numerous rivers, interrupted by large waterfalls and extensive rapids, drain the geologically ancient Guiana Shield Highlands. We describe a new armoured catfish genus and two new species endemic to the upper Ireng and Kuribrong rivers, respective tributaries of the Amazon and Essequibo basins in western Guiana. Corymbophanes ameliae sp. nov. is distinguished by having vermiculations on the abdomen, bands on the caudal fin, the anal fin i,5 and narrow caudal peduncle. Yaluwak primus gen. & sp. nov. is distinguished by having evertible cheek odontodes, a plated snout, a tall caudal peduncle and absence of adipose fin and iris operculum. We present a new molecular phylogenetic analysis inclusive of these and several related genera that suggests that the Corymbophanes clade (Araichthys, Corymbophanes, Cryptancistrus, Guianancistrus, Hopliancistrus and Yaluwak) originated in the Guiana Shield with secondary dispersal to the Brazilian Shield. Within the Guiana Shield, relationships among Corymbophanes and Yaluwak are consistent with geodispersal between drainages via headwater capture, although an uplift-mediated relictual distribution cannot be ruled out. ND2 haplotype structure among C. ameliae populations suggests that ichthyofaunal diversity on the Guiana Shield escarpment is shaped not only by inter-, but also intrafluvial barriers to gene flow.

Keywords: Amaila Falls, Amazonian Craton, Guianas, Ireng River, Kuribrong River, Rio Maú, Potaro River, sexual dimorphism

Figure 5. Corymbophanes ameliae paratype, ROM 89897, 80.8 mm SL, Guiana, Region 8 (Potaro–Siparuni), Kuribrong River at rapids ~15 min upstream of upstream Kuribrong Camp, ..., 454 m a.s.l., 19–20 March 2011.

Photos by Nathan K. Lujan.

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Corymbophanes ameliae Lujan et al., sp. nov.

Etymology: Named for Amelia, a Patamona Amerindian girl who disappeared near Amaila Falls in the late 19th century. The falls are named for her, but her name was misspelled.

Figure 2. Phylogenetic relationships of taxa within the tribe Ancistrini (Loricariidae: Hypostominae), including the new genus and species Yaluwak primus and new species Corymbophanes ameliae. Relationships based on Bayesian analysis of a 4123 bp alignment consisting of three mitochondrial (16S, Cytb, ND2) and two nuclear loci (RAG1, RAG2; Table 2). Node numbers correspond to Bayesian posterior probability (BI) and maximum likelihood (ML) support values in Table 3; numbers in red indicate BI < 0.90, whereas numbers in italics indicate ML < 60. Green, red and blue colours for Corymbophanes ameliae correspond to those in Figure 3. MC = main channel, Trib = tributary

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Figure 1. Distributions of Corymbophanes and Yaluwak specimens examined in this study. OC = Oung Creek.

Figure 8. Holotype of Yaluwak primus, CSBD F1722, 122.9 mm SL, Guiana, Region 8 (Potaro–Siparuni), 5. Sukwabi Creek, East Fork, downstream of Wotowanda Falls, ..., 634 m a.s.l., 13 January 2016.

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Yaluwak Lujan & Armbruster, gen. nov. 

Etymology: Yaluwak is the Patamona Amerindian word for this species (and used generally for larger loricariids). The pronunciation of the ‘l’ in Yaluwak is a guttural ‘lr’ sound. Name is treated as masculine. 

Included species: Yaluwak contains only the type species 

Yaluwak primus Lujan, Armbruster & Werneke, sp. nov. 

Etymology: The species epithet primus comes from the same Latin word meaning first, foremost, chief or principal and is in reference to the large body size of the species and the fact that it retains the evertible cheek odontodes, likely inherited from the common ancestor of the Yaluwak/Corymbophanes clade. This species name was also inspired by our indefatigable Patamona guide, Mr Primus Peters, who led the collection effort for this species and assisted in innumerable other ways during our 2016 expedition to the upper Ireng River.

Nathan K. Lujan, Jonathan W. Armbruster, David C. Werneke, Túlio Franco Teixeira and Nathan R. Lovejoy. 2020. Phylogeny and Biogeography of the Brazilian–Guiana Shield Endemic Corymbophanes Clade of Armoured Catfishes (Loricariidae). Zoological Journal of the Linnean Society. 188(4); 1213–1235. DOI: 10.1093/zoolinnean/zlz090  

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[Ichthyology • 2020] Panaque nigrolineatus laurafabianae • A New, Commercially exploited Subspecies of Ornamental Wood-eating Pleco (Loricariidae: Hypostominae) from the Guaviare River Basin in Colombia

 Panaque nigrolineatus laurafabianae 

Ortega-Lara & Lujan, 2020

Watermelon Pleco  ||  DOI: 10.11646/zootaxa.4732.3.3

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Abstract

The suckermouth armored catfish genus Panaque contains seven valid species, including the Royal Pleco, Panaque nigrolineatus, which has long been popular as an ornamental aquarium fish and was originally described from the Apure River basin in Venezuela. We examine a phenotypically distinct population of P. nigrolineatus from the Guaviare River in southern Colombia at the southwesternmost corner of the Orinoco River basin. In contrast to typically boldly striped populations from closer to the type locality of P. nigrolineatus, the Guaviare River basin population is usually boldly spotted, earning them the common name Watermelon Pleco in the aquarium fish trade. Because of the commercial popularity of this distinctive color morph, it is heavily exploited for export to the global ornamental fish trade. We find that the Guaviare River P. nigrolineatus laurafabianae is not only distinct geographically and in color pattern, but is also morphometrically diagnosable from P. nigrolineatus individuals from outside the Guaviare River basin. However, relatively subtle phenotypic differences, invariance in nuclear DNA markers, < 0.5% divergence in mitochondrial DNA markers 16S, cytb, and ND2, and the non-monophyly of Guaviare River populations prevent us from robustly inferring species-level distinctiveness of the Watermelon Pleco. We therefore propose to recognize this population as a distinct subspecies.

Keywords: Loricariidae, Taxonomy, Neotropics, Orinoco, coloration, wood-eating, ornamental aquarium fishes

 Armando Ortega-Lara and Nathan K. Lujan. 2020. Panaque nigrolineatus laurafabianae, A New, Commercially exploited Subspecies of Ornamental Wood-eating Pleco (Loricariidae: Hypostominae) from the Guaviare River Basin in Colombia. Zootaxa. 4732(3); 393–408. DOI: 10.11646/zootaxa.4732.3.3  

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[Ichthyology • 2017] Multilocus Molecular Phylogeny of the Ornamental Wood-eating Catfishes (Siluriformes, Loricariidae, Panaqolus and Panaque) reveals Undescribed Diversity and Parapatric Clades

Fig. 1. Voucher specimens examined in this study, from the new subgenus Panafilus (lyretail clown plecos):
(1) Pf. albivermis, (2) Pf. albomaculatus, (3) Pf. nocturnus, (4) Pf. n. sp. Huallaga L329, (5) Pf. n. sp. Huallaga L351, (6) Pf. n. sp. Ucayali L425, (7) Pf. n. sp. Moa L453, (8) Pf. n. sp. Napo L466, (9) Pf. nix, (10) Pf. n. sp. Madeira;
 new subgenus Panaqoco (Orinoco clown plecos): (11) Pc. maccus, (12) Pc. n. sp. Tomo L465, (13) Pc. n. sp. Orinoco L448;
new subgenus Panaqolus (the tiger clown plecos): (14) Pq. changae, (15) Pq. gnomus, (16) Pq. purusiensis, (17) Pq. n. sp. Curua Una, (18) Pq. n. sp. Tocantins L002, (19) Pq. n.sp. Negro L169, (20) Pq. n. sp. Ucayali L206, (21) Pq. n. sp. Branco L306, (22) Pq. n. sp. Amazon L397, (23) Pq. tankei, (24) Pq. n. sp. Itaya L459;
and new genus Pseudoqolus: (25) Ps. koko.

DOI: 10.1016/j.ympev.2016.12.040 

Highlights

• Respective genera Panaqolus (exclusive of putative congener ‘Panaqolus’ koko) and Panaque are strongly monophyletic. 

• Within Panaqolus s.s., species are distributed across three strongly monophyletic clades.

• New subgenera are erected for each of the three subclades within Panaqolus.

• A new genus is erected for the enigmatic species ‘Panaqolus’ koko.

• Western tributaries of the Amazon Basin are an epicenter of wood-eating catfish diversity.

Abstract

Approximately two-dozen species in three genera of the Neotropical suckermouth armored catfish family Loricariidae are the only described fishes known to specialize on diets consisting largely of wood. We conducted a molecular phylogenetic analysis of 10 described species and 14 undescribed species or morphotypes assigned to the wood-eating catfish genus Panaqolus, and four described species and three undescribed species or morphotypes assigned to the distantly related wood-eating catfish genus Panaque. Our analyses included individuals and species from both genera that are broadly distributed throughout tropical South America east of the Andes Mountains and 13 additional genera hypothesized to have also descended from the most recent common ancestor of Panaqolus and Panaque. Bayesian and maximum likelihood analyses of two mitochondrial and three nuclear loci totaling 4293 bp confirmed respective monophyly of Panaqolus, exclusive of the putative congener ‘Panaqolus’ koko, and Panaque. Members of Panaqolus sensu stricto were distributed across three strongly monophyletic clades: a clade of 10 generally darkly colored, lyretail species distributed across western headwaters of the Amazon Basin, a clade of three irregularly and narrowly banded species from the western Orinoco Basin, and a clade of 11 generally brown, broadly banded species that are widely distributed throughout the Amazon Basin. We erect new subgenera for each of these clades and a new genus for the morphologically, biogeographically and ecologically distinct species ‘Panaqolus’ koko. Our finding that perhaps half of the species-level diversity in the widespread genus Panaqolus remains undescribed illustrates the extent to which total taxonomic diversity of small and philopatric, yet apparently widely distributed, Amazonian fishes may remain underestimated. Ranges for two Panaqolus subgenera and the genus Panaque overlap with the wood-eating genus Cochliodon in central Andean tributaries of the upper Amazon Basin, which appear to be a global epicenter of wood-eating catfish diversity.

Keywords: Neotropics; undescribed species; L-numbers; biogeography; western Amazon; introgression

Conclusions

Our finding that approximately half of the species-level diversity in the widespread genus Panaqolus may remain undescribed is illustrative of the extent to which total taxonomic diversity of even commercially exploited Amazonian fish lineages may remain underestimated by current taxonomies. Our erection of strongly monophyletic subgenera for the species-rich genus Panaqolus should help to facilitate both the conservation and taxonomic description of species by making at least the major clades easier to identify and by restricting the number of congeners that future taxonomists would have to examine to adequately diagnosis new Panaqolus species. Moreover, our strong phylogenetic support for large-scale biogeographical influence on the diversification of Panaqolus helps to justify and spatially delimit studies by regional researchers with regular access only to collections representing regional diversity.

It is clear from the biogeographical patterns observed in both Panaqolus and Panaque, as well as the Cochliodon group examined elsewhere (e.g., Armbruster, 2003), that Andean affluents of the southwestern Amazon Basin are an epicenter of wood-eating fish diversity, with some drainages having up to five different sympatric but unrelated species of wood-eating catfish coexisting on the same pieces of submerged wood. See Lujan et al. (2011) for a detailed study of trophic resource partitioning in one such diverse assemblage.

Nathan K. Lujan, Christian A. Cramer, Raphael Covain, Sonia Fisch-Muller and Hernán López-Fernández. 2017. Multilocus Molecular Phylogeny of the Ornamental Wood-eating Catfishes (Siluriformes, Loricariidae, Panaqolus and Panaque) reveals Undescribed Diversity and Parapatric Clades. Molecular Phylogenetics and Evolution. In Press.  DOI: 10.1016/j.ympev.2016.12.040