A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin, with a discussion of historical biogeography of western Amazonas and Paraguay River basins

Abstract

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.

Taxonomic revision of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), with descriptions of four new species

“…After that there was a gap in contributions to the genus until Ghazzi (2005), who described S. kneri (= S. kneri ), however, without comments on the taxonomy of the genus. Posteriorly, it was not only until Londoño‐Burbano (2018) and Londoño‐Burbano and Britto (2022) that additional species were included in the genus. On the contrary, Rapp Py‐Daniel (1997), Covain et al (2016), and Londoño‐Burbano and Reis (2021) included the genus as part of their phylogenetic analyses of Loricariinae, all of them finding it as monophyletic, with Rapp Py‐Daniel and Londoño‐Burbano and Reis offering morphological synapomorphies for Sturisoma .…”

“…—Gosline, 1945:109 (reference); Fowler, 1954:123 (in synonym list; synonym of S . rostratum ); Arámburu et al, 1962:53 (as present in Argentina); Ringuelet et al, 1967:414 (reference); Isbrücker, 1980:93 (cited in Loricariidae species catalog); Burgess, 1989:440 (reference); Gómez & Chebez, 1996:63 (as present in Argentina, Misiones); Britski et al, 1999:129 (list of species; present at Pantanal, Paraguay River basin, Brazil); Isbrücker, 2001:29 and 32 (as valid in Loricariidae; German version); Isbrücker, 2002:29 (as valid in Loricariidae; English version); Ferraris, 2003:345 (valid in Loricariinae; distribution; type series); López et al, 2003:49 (as present in Argentina); Menni, 2004:81 (as present in Argentina); Ferraris, 2007:299 (valid in Loricariinae; distribution; type series); Mirande & Koerber, 2015:44 (as present in Argentina); Covain et al, 2016:514 (valid as part of Sturisoma , subtribe Farlowellina; phylogenetic analysis of Loricariinae); Londoño‐Burbano, 2018:1000 (valid in Sturisoma ; identification key of the genus); Londoño‐Burbano & Reis, 2021:16 (valid as part of Sturisoma , tribe Farlowellini; not included in phylogenetic analysis of Loricariinae); Londoño‐Burbano & Britto, 2022:11 (valid in Sturisoma ; genetic distances analysis; phylogenetic analysis). Cardoso et al, 2023:516 (molecular delimitation of Sturisoma individuals from La Plata River, Argentina).…”

“…guentheri , or S . nigrirostrum ); Burgess, 1989:440 (reference); Isbrücker, 2001:29 and 32 (as valid in Loricariidae; German version); Isbrücker, 2002:29 (as valid in Loricariidae; English version); Ferraris, 2003:345 (valid in Loricariinae; distribution; type series); Ferraris, 2007:299 (valid in Loricariinae; distribution; type series); Covain et al, 2016: 514 (valid as part of Sturisoma ; phylogenetic analysis of Loricariinae; not included in phylogenetic analysis); Londoño‐Burbano, 2018:1000 (valid in Sturisoma ; analysis of holotype included; identification key of the genus); Londoño‐Burbano & Reis, 2019:774 (valid as part of Sturisoma ; comparison with Sturisomatichthys ; analysis of holotype included); Londoño‐Burbano & Reis, 2021:70 (valid as part of Sturisoma , tribe Farlowellini; not included in phylogenetic analysis of Loricariinae); Londoño‐Burbano & Britto, 2022:13 (as valid in Sturisoma ; compared to new species).…”

“…Sturisoma graffini Londoño‐Burbano, 2018:1002, Figures 1a, 2a, and 3–5 (type locality: Picaflor Creek, at Pakitza guard post, Castanel Trail #12 to Caña Brava Trail #16, Madre de Dios River basin, Amazonas, Peru; holotype MUSM 58700, length 187.6 mm SL); Londoño‐Burbano & Reis, 2019:801 (valid as part of Sturisoma ; comparison with Sturisomatichthys ; photograph of anterior portion of body in ventral view of holotype); Londoño‐Burbano & Reis, 2021:16 (valid as part of Sturisoma , tribe Farlowellini; included in phylogenetic analysis of Loricariinae); Londoño‐Burbano & Britto, 2022:13 (as valid in Sturisoma ; compared to new species).…”

“…rostratum . The last taxonomic addition to Sturisoma were the description of S. reisi Londoño‐Burbano & Britto, 2022 from the Madeira River in Bolivia and Brazil, with a molecular delimitation of the species and phylogenetic relationships to some congeners, and a study of molecular delimitation of Sturisoma individuals from La Plata River, Argentina (Cardoso et al, 2023). To date,10 species are recognized as valid for the genus, following Fricke et al (2023).…”