Sharp Nosed Catfish

Dorsal spines (total): 1; Dorsal soft rays (total): 7; Analspines: 0; Analsoft rays: 20 - 22

Feeds mainly on higher plants, including a variety of fruits, but also takes ants, grasshoppers, beetles, small crabs and prawns.

Feeds mainly on higher plants, including a variety of fruits, but also takes ants, grasshoppers, beetles, small crabs and prawns.

Hemipimelodus macrorhynchus Weber, 1913

Hemipimelodus aaldareni Hardenberg, 1936:367–368 [Middle Digul River].

USNM 217075, Fly 75–1, 3: 348–463 mm.

Hemipimelodus macrorhynchus, endemic to the rivers of central-southern New Guinea, is immediately distinguishable from all other ariids in this region by the shape of its head and its color in life. Snout sharp, pointed, and dorsally flattened, strongly indented at nostrils. Eyes lateral or slightly ventrolateral, 23–31 in specimens 136–463 mm (negatively allometric). Barbels long, maxillary barbel extending beyond tip of pectoral spine. Tooth bands broad transversely, but exceptionally narrow anteroposteriorly (Figure 20g); tooth band of upper jaw entirely or almost entirely exposed when mouth is closed. Lips thin, tightly applied. Gill rakers on first gill arch 14–15; gill rakers absent on posterior face of first and second gill arch except for one or two small, weak rakers on upper limb. Upper limb of second gill arch with a moderately thick epithelial fold or valve projecting into branchial passage. Roof of pharynx relatively smooth. Pectoral fin with 11 segmented rays. Anal fin pterygiophores 20–21. Free vertebral centra posterior to Weberian apparatus 45–46 (2: 348–373 mm). Color in life: dorsum of snout iridescent sea green with bronze reflections; dorsum of body and posterior portion of head dark brown with bronze reflections; ventrum off-white, dusky or slightly brownish; barbels blackish brown.

Hemipimelodus macrorhynchus does not seem very closely related to any other ariid I have seen. I have compared my specimens from the Fly with two syntypes of H. macrorhynchus from the Lorentz River (ZMA 111.085, 137–144 mm) and find they are similar except the distinctive shape of the head is not so well developed in the syntypes due to their small size. I agree with Desoutter (1977:13) that H. aaldareni is a synonym of H. macrorhynchus. Han Nijssen kindly compared my description and photograph of the 463-mm specimen of H. macrorhynchus from the Fly with Hardenberg's 460-mm (total length) holotype of H. aaldareni and found them conspecific. The holotype has snout very sharp in lateral view, indented at nostrils; dorsomedian portion of snout flattened, even concave; all barbels dark brown; and tooth band of upper jaw completely exposed when mouth is closed.

Potamosilurus macrorhynchus, the sharp-nose catfish, is a species of sea catfish endemic to the island of New Guinea where it is found in both Papua New Guinea and in West Papua, the Indonesian part of the island. It is a strictly fresh water catfish and grows to a length of 50 cm.