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| Chaetostoma sacramento Meza-Vargas, Ramirez & Lujan, 2024 |
Abstract
A new species in the rubbernose catfish genus Chaetostoma is described from the Aguaytia, Pisqui and Palcazu Rivers, which drain the Pampa de Sacramento Region in the Ucayali River drainage of central Peru. The new species is distinguished from congeners, except C. anomalum, C. branickii, C. dorsale, C. leucomelas, C. microps, C. nudirostre, C. palmeri and C. thomsoni by having distinct, white, variably-shaped spots or vermiculations ½–2× nostril diameter on dark grey to black background on the head (vs. spots absent or black on light-coloured background). The new species is distinguished from C. anomalum, C. branickii, C. dorsale, C. microps, C. nudirostre and C. thomsoni by having highly variable, distinct white spots, vermiculations or bands ½–10× nostril diameter on the body, from C. leucomelas by having dorsal and caudal fin indistinctly and variably-patterned with zero to four bands (vs. dorsal and caudal fin consistently having five or more uniform bands) and from C. palmeri by having two predorsal plates (vs. three), supraoccipital excrescence present (vs. absent) and pelvic-fin insertion slightly posterior to dorsal-fin insertion (vs. pelvic-fin insertion at middle of dorsal-fin base). Species delimitation analyses of the COI and Cytb genes further support the recognition of this new species.
Key Words: Amazon, Andes, Chaetostoma clade, freshwater, molecular, Neotropical, taxonomy
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| Live holotype of Chaetostoma sacramento MUSM 72045, 65.1 cm, collected from the Yamino River, a tributary of the Aguaytía River. Photos by D. Faustino. |
Chaetostoma sacramento sp. nov.
Chaetostoma sp. nov. Ucayali: Lujan et al. (2015b) [molecular phylogeny].
Diagnosis: Chaetostoma sacramento can be diagnosed from all congeners, except C. anomalum, C. branickii, C. dorsale, C. leucomelas, C. microps, C. nudirostre, C. palmeri and C. thomsoni by having distinct, white, variably-shaped spots or vermiculations ½–2× nostril diameter on grey to brown background on the head (vs. spots absent or black on light-coloured background). Chaetostoma sacramento is distinguished from C. anomalum, C. branickii, C. dorsale, C. nudirostre and C. thomsonii by having highly variable, small to large distinct white spots, vermiculations or bands on the body (vs. spots, vermiculations or bands absent or black on light-coloured background), from C. anomalum by having adipose fin fully formed (vs. rudimentary), from C. dorsale by having uniformly brown adipose fin (vs. adipose fin with black spot), from C. leucomelas by having golden spots across the dorsal fin rays (vs. light bands), from C. microps by having eight branched dorsal-fin rays (vs. nine), from C. nudirostre by having curved cheek odontodes (vs. strait), from C. palmeri by having two predorsal plates (vs. three), excrescence present (vs. absent) and pelvic-fin insertion slightly posterior of dorsal-fin insertion (vs. pelvic-fin insertion at middle of dorsal-fin base).
Etymology: The species epithet sacramento refers to the plain (pampa) in central Peru between the Huallaga and Ucayali Rivers, approximately delimited by the Pisqui River in the north and Palcazu River in the south. Chaetostoma sacramento is currently known exclusively from this region, known as the Pampa de Sacramento, which occupies a valley between Huánuco and Ucayali provinces that is part of the Peruvian subandean belt and surrounds Boqueron del Padre Abad in the Cordillera Azul. The Pampa de Sacramento was first encountered by Europeans on 21 June 1726, by an expedition led by Don Juan Nunez Lobo and was christened Pampa del Sacramento to commemorate the Catholic ceremony of the Corpus Christi. Subsequent Franciscan missionaries highlighted the rich ethnic diversity of this region (IBC 2016). A noun in apposition.
Vanessa Meza-Vargas, Jorge L. Ramirez and Nathan K. Lujan. 2024. The Ornate Rubbernose Pleco (Siluriformes, Loricariidae, Chaetostoma), A New Species from the Ucayali River Basin, Peru. Zoosystematics and Evolution 100(4): 1387-1400. DOI: doi.org/10.3897/zse.100.118522
