Hemipsilichthys, EIGENMANN & EIGENMANN, 1889

Reis, Roberto E., Pereira, Edson H. L. & Armbruster, Jonathan W., 2006, Delturinae, a new loricariid catfish subfamily (Teleostei, Siluriformes), with revisions of Delturus and Hemipsilichthys, Zoological Journal of the Linnean Society 147 (2), pp. 277-299 : 280-281

HEMIPSILICHTHYS EIGENMANN & EIGENMANN

Xenomystus Lütken (1874) : 217 (type species: Xenomystus gobio Lütken, 1874 by original designation. Name preoccupied in fishes by Xenomystus Günther, 1868 as a subgenus of Notopterus ).

Hemipsilichthys Eigenmann & Eigenmann, 1889: 46 (type species: Xenomystus gobio Lütken, 1874 ; name in substitution to Xenomystus Lütken, 1874 ).

Upsilodus Miranda Ribeiro, 1924: 365 (type species: Upsilodus victori Miranda Ribeiro, 1924 by monotypy).

Diagnosis: No uniquely derived features were found to diagnose Hemipsilichthys . The following features are derived for Hemipsilichthys but are shared with a number of other loricariid groups: (1) anterior and posterior edges of hyohyal bone concave, making it spindle-shaped (character 21–0); (2) some of the bifid neural spines under the dorsal fin are perforated above the spinal cord (character 126–1); (3) adductor fossa of the pectoral girdle displaced laterally by the development of anterior and posterior rims of the fossa (character 152–1); and (4) ventral ridge of the pelvic basipterygium tall (a reversion, character 172–0).

In addition, Hemipsilichthys can be easily recognized by the combination of a high preadipose keel, formed by the azygous preadipose plates, almost symmetrically bifid teeth ( Fig. 2 ) on premaxilla and dentary, small eye (orbital diameter 8.6–16.9% HL), and dorsal-fin membrane not or slightly extended posteriorly but never in contact with the first preadipose plate.

KEY TO SPECIES OF HEMIPSILICHTHYS

1. Dorsal series of plates reduced, with no plates between dorsal-fin origin and the end of the adipose fin; eye comparatively smaller (orbital diameter 8.6–11.8% HL); dorsal-fin spinelet absent..................................... ................................................... Hemipsilichthys papillatus (Rio Preto basin, Rio Paraíba do Sul drainage)

1′. Dorsal series of plates complete, with plates between head and caudal peduncle; eye comparatively larger (orbital diameter 12.0–16.9% HL); dorsal-fin spinelet present ...................................................................... 2

2. Dorsal fin with seven branched rays; papillae in upper lip forming transversely elongate skin folds; eye comparatively smaller (orbital diameter 12.0–14.7% HL); dorsal-fin spinelet rectangular or oval-shaped ( Fig. 3 ) ................................................................................. Hemipsilichthys gobio (Rio Paraíba do Sul basin)

2′. Dorsal fin with eight (rarely seven or nine) branched rays; papillae in upper lip transversely elongate but not fused to form skin folds; eye comparatively larger (orbital diameter 15.3–16.9% HL); dorsal-fin spinelet V-shaped ( Fig. 3 ) ........................................... Hemipsilichthys nimius (Rio Perequê-Açu and Taquari basins)

Figures

Figure 2. Teeth of the Delturinae. A, right premaxilary tooth of Delturus angulicauda, USNM 318180, lateral view. Scale bar 1 mm. B–H, dorsal view of right premaxillary tooth crown. B, D. parahybae, MCZ 7726. C, D. angulicauda, USNM 318180. D, D. carinotus, MCP 28039. E, D. brevis, MZUSP 69858. F, Hemipsilichthys papillatus, MCP 21423. G, H. nimius, MCP 31990. H, H. gobio, MCP 19780. Scale bar 250 µm.

Figure 3. Dorsal-fin spinelet of the Delturinae. A, Hemipsilichthys gobio, MCP 19780. B, H. nimius, MCP 31990. C, Del- turus brevis, MZUSP 69858. Scale bar 2 mm. DS1, first dorsal-fin spine or spinelet; DS2, second dorsal-fin spine.