A New Species of Nanobagrus (Teleostei: Bagridae) from Southern Borneo
Nanobagrus immaculatus, a new species of bagrid catfish, is described from the Kahayan River drainage in southern Borneo. Nanobagrus immaculatus is most readily distinguished from congeners in having a uniformly dark-colored body lacking pale spots or patches (vs. pale spots or patches always present), larger eye (16.7–18.2% HL vs. 9.0–16.1), and a longer adipose-fin base (24.9–26.6% SL vs. 12.8–21.6). The synapomorphies used to diagnose Nanobagrus are reviewed and re-examined. Pseudomystus fuscus is hypothesized to be more closely related to Nanobagrus than to all other Pseudomystus and is hereby reassigned to the former genus.Abstract
Nanobagrus immaculatus, MZB 10720, holotype, 29.3 mm SL; Borneo, Kalimantan Tengah, stream about 14 km NW of Palangkaraya.
Lateral views of other species of Nanobagrus showing color pattern: (A) N. armatus, ZRC 49192, 19.8 mm SL; (B) N. fuscus, ZRC 46144, 39.0 mm SL; (C) N. nebulosus, ZRC 44196, 23.4 mm SL; (D) N. stellatus, ZRC 44162, 28.0 mm SL. Figures not to scale.
Map showing distributions of Nanobagrus species.
Posterior half of neurocranium, in dorsal view, of: (A) Nanobagrus fuscus, ZRC 46144, 36.0 mm SL; (B) Pseudomystus leiacanthus (after Mo, 1991:fig. 28). Posterior cranial fontanel indicated by stippling. Scale bar represents 1 mm.
Nuchal plate elements, in dorsal view, of: (A) Nanobagrus fuscus, ZRC 46144, 36.0 mm SL; (B) Pseudomystus stenomus, ZRC 42760, 37.7 mm SL. Scale bar represents 1 mm.
Contributor Notes
1Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore, 6 Science Drive 2 #03-01, Singapore 117546 dbsnhh@nus.edu.sg
Section Editor: C. J. Ferraris.