A New Genus and Species of Weakly Armored Catfish from the Upper Mazaruni River, Guyana (Siluriformes: Loricariidae)
Paulasquama callis is a new genus and species of partially deplated ancistrin loricariid from the Waruma River, a tributary of the upper Mazaruni River, in northwestern Guyana. Paulasquama differs from all other described hypostomines by lacking plates in an oval area lateral to the mesethmoid, by having small plates in the dorsal series below the dorsal fin (less than half the typical size of other loricariids), and by having a fleshy keel on the preadipose plate and slightly anterior. The opercle of Paulasquama is sickle-shaped as in basal ancistrins, but has a posterior connection to the hyomandibula as in derived members of the Ancistrus clade.
Dorsal view of left side of head of cleared-and-stained specimen of Paulasquama callis, AUM 50000, 38.0 mm SL. Note that the snout plates (SP) get smaller and do not touch one another medially. Photo by J. W. Armbruster.
Holotype of Paulasquama callis, 47.2 mm SL, UG 1654, Guyana, Cuyuni-Mazaruni, Waruma River, Kako River–Mazaruni River drainage. Photos by J. W. Armbruster.
Map of Guyana with type locality of Paulasquama callis indicated by dot.
Opercles, medial view with associated bones of the suspensorium; scale = 1 mm; shaded area is cartilage. (A) Pseudancistrus barbatus, CAS 56702; (B) Paulasquama callis, paratype, AUM 50000; (C) Dolichancistrus pediculatus, CAS 78820.
Contributor Notes
Associate Editor: C. J. Ferraris.