title: A new species of Limatulichthys Isbrücker & Nijssen (Loricariidae, Loricariinae) from the western Guiana Shield .
abstract: Limatulichthys nasarcus n. sp. is described as a new species based on 15 specimens from the Ventuari and Caura Rivers in Southern Venezuela. The new species can be distinguished from its only congener, L. griseus, by the presence of anterior abdominal plates half the size of those at center of abdomen (vs. plates similar in size); distinct spots less than half of diameter of naris across entire dorsum, including snout and head (vs. indistinct dorsal spots larger or equal than diameter of naris); lateral portions of head and opercle with dark well-defined spots larger than those on dorsum (vs. spots on lateral portions of head and opercle equal in size to those on remainder of body); snout profile in dorsal view broadly rounded (vs. acutely triangular); head longer (21.4-24.2 SL vs. 17.7-21.0%); and anal fin longer (15.7-18.0 SL vs. 13.7-15.6%). Distinctiveness of the two species is further supported by their non-overlapping distribution in multivariate morphospace. The disjunct distribution of L. nasarcus across both the Caura and Ventuari rivers exclusive of the main Orinoco River channel contributes to a growing body of evidence supporting the historical connection between headwaters of these drainages. The hypothesized existence of a 'proto-Berbice' paleodrainage provides one explanation for such a connection.
authors.affiliation: Pontifícia Universidade Católica do Rio Grande do Sul, Laboratório de Sistemática de Vertebrados, Avenida Ipiranga 6681, P. O. Box 1429, 90619-900 Porto Alegre, RS, Brazil. Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada. Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, ON, M5S 3B2, Canada.; Email: alondonoburbano@gmail.com.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Londoño-Burbano
authors.affiliation: Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada. Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, ON, M5S 3B2, Canada.; Email: stephanie.lefebvre@mail.utoronto.ca.
authors.forename: Stéphanie L
authors.initials: SL
authors.lastname: Lefebvre
authors.affiliation: Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada.zx Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, ON, M5S 3B2, Canada.; Email: unknown.
authors.forename: Nathan K
authors.initials: NK
authors.lastname: Lujan
mesh_terms: D063147:Animal Distribution; D000818:Animals; D005399:Fishes / Q000033:anatomy & histology* / Q000145:classification* / Q000502:physiology; D045483:Rivers; D014687:Venezuela