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| Pimelodella guato |
Abstract
A new species of Pimelodella is described from the rio Paraguai basin in Mato Grosso do Sul and Mato Grosso States, Brazil. The new species distinguishes from all other members of the genus based on a unique combination of characteristics, which include: dorsal profile straight from snout to dorsal-fin, maxillary barbel reaching at least the anal-fin terminus when parallel to main body axis, robust dorsal-fin spine bearing small spinules along three-fourths of its posterior margin, 41–42 total vertebrae (rarely 43 or 44), 13–23 large and retrorse blades at the posterior margin of the pectoral-fin spine, and dorsolateral region of body slightly darkened. This study also discusses the ichthyofaunal similarities between the Paraguai and Amazon basins, shedding light on their biogeographic history. Additionally, the research includes considerations about the sexual dimorphism of Pimelodella and provides an identification key for the Pimelodella species found in the Paraguai basin.
Keywords: Biogeography, Catfishes, Identification key, Sexual dimorphism, Taxonomy.
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| Pimelodella guato, holotype, ZUFMS-PIS 8515, 78.5 mm SL, Brazil, Mato Grosso do Sul, Corumbá municipality, rio Paraguai basin, rio Miranda, sandy beaches at Passo do Lontra region, ... A. Dorsal; B. Left lateral; and C. Ventral views. Scale bar = 1 cm. |
Pimelodella guato, new species
Diagnosis. Pimelodella guato differs from all Pimelodella species except P. boliviana, P. chaparae, P. cristata, P. cruxenti, P. dorseyi, P. geryi, P. gracilis, P. howesi, P. humeralis, P. laurenti, P. longibarbata, P. longipinnis, P. martinezi, P. megalops, P. mucosa, P. notomelas, P. odynea, P. ophthalmica, P. parnahybae, P. serrata, P. steindachneri, P. taeniophora, P. tapatapae, P. wesselii, and P. witmeri by the long maxillary barbel, reaching at least the anal-fin terminus when parallel to main body axis (vs. reaching at best posterior limit of anal-fin base). It differs from P. longipinnis and P. tapatapae by having the supraoccipital process reaching the anterior nuchal plate (vs. not reaching, gap between distal terminus of supraoccipital process and anterior nuchal plate ca. 20–25% of supraoccipital process length). It differs from P. boliviana, P. cruxenti, P. geryi, P. laurenti, P. martinezi, P. megalops, P. notomelas, P. odynea, and P. taeniophora by having a robust dorsal-fin spine, bearing small, straight spinules along three-fourths of its posterior margin (vs. dorsal-fin spine not particularly robust, with posterior margin spinules inconspicuous or absent). It differs from P. cristata, P. dorseyi, P. gracilis, P. howesi, P. humeralis, P. ophthalmica, P. parnahybae, P. steindachneri, P. wesselii,and P. witmeri by usually having 41–42 (rarely 43 or 44) total vertebrae (vs. always 43–44 in P. howesi; 46 or more in the remaining species). It further differs from P. howesi by having the dorsolateral region of body slightly darkened (vs. not darkened), dorsal fin with light brown stripe near its origin, followed by a hyaline stripe, and distal half dark (vs. basal half of dorsal fin hyaline, and distal half dark), and by the dorsal lamina of the Weberian apparatus reaching the ventral margin of the supraoccipital process only at its first third (vs. dorsal lamina reaching the supraoccipital process along all its extension). It differs from P. mucosa and P. longibarbata by the preoperculomandibular laterosensory canal openings at dentary not particularly large (vs. large openings). It differs from P. chaparae, P. longibarbata, and P. serrata by the wide midlateral stripe (vs. narrow) and by the dorsal lamina of the Weberian apparatus reaching the ventral margin of the supraoccipital process only at its first third (vs. first half in P. longibarbata; and almost its entire extension in P. chaparae and P. serrata) (Figs. 2A, D).
Etymology. The species name guato is in honor of the indigenous Guató people, who are affectionately known as “people of the Pantanal waters” due to their primary mode of transportation, canoes. Historically, the Guató people inhabited an extensive area along the rio Paraguai (Schmidt, 1942). However, in the 1940s, they began to lose their territory due to cattle ranching, and many relocated to cities such as Cáceres and Corumbá. This dispersal led to a reduction in the Guató population, and since then, they have been fighting for recognition of their ethnicity and the demarcation of their lands (Costa, 2015). The choice of guato is a homage to the resilience and cultural significance of these people who inhabit the same region where the new species is found. It also recognizes the ongoing struggles with land delimitation that indigenous communities continue to face, particularly in Brazil. A noun in apposition.
Veida Pierre and Veronica Slobodian. 2024. A New Species of Pimelodella (Siluriformes: Heptapteridae) from the Paraguai Basin, Brazil, with a discussion regarding its distribution. Neotrop Ichthyol. 22(1): e230110. DOI: 10.1590/1982-0224-2023-0110