Broad Snouted Catfish

Dorsal spines (total): 1; Dorsal soft rays (total): 7; Analspines: 0; Analsoft rays: 16 - 20

Omnivorous, feeding on terrestrial arthropods, aquatic insects, plants, molluscs, prawns and fishes.

Omnivorous, feeding on terrestrial arthropods, aquatic insects, plants, mollusks, prawns and fishes (Ref. 2847).

Arius acrocephalus Weber, 1913

Arius digulensis Hardenberg, 1936:369 [Middle Digul River].

USNM 217055, Fly 75–1, 2: 323–479 mm.

ZMA 115.537, Fly 75–3, 1: 447 mm.

USNM 217056, Fly 75–4, 3: 313–376 mm.

USNM 217057, Fly 75–6, 1: 344 mm.

USNM 217058, Fly 75–8, 5: 117–361 mm.

USNM 217059, Fly 75–9, 2: 134–175 mm.

USNM 217060, Fly 75–10, 14: 97.8–198 mm.

USNM 217061, Fly 75–14, 1: 235 mm.

Arius acrocephalus is apparently endemic to the rivers of central-southern New Guinea. It is the only ariid known from highland habitats of the Upper Fly and is very common in lowland habitats of the Upper Fly, but it was not observed in the Middle or Lower Fly. It is a moderately broad-headed, broad-mouthed species; snout slightly pointed; tooth band of upper jaw largely included to half-exposed when mouth is closed. Maxillary barbel usually reaching to or slightly beyond origin of pectoral spine. Eyes lateral, 22–26 in specimens 175–361 mm (slight negative allometry). Gill rakers on first gill arch 14–16; no gill rakers on posterior face of first and second gill arches. Upper limb of second gill arch with a thickened, papillate lobe (evident in specimens of 75–447 mm); similar but much smaller lobes present on upper limbs of other free gill arches. Young and juveniles with a soft anterior projection of snout, particularly pronounced in specimens of 75–100 mm. Specimens over 200 mm have a broad median depression on dorsum of snout between prominent ridge- or browlike anterolateral wings of cephalic shield, and a pronounced nuchal hump. Pectoral fin usually with 11 segmented rays. Anal fin pterygiophores 20–22. Free vertebral centra posterior to Weberian apparatus 45–49 (6:152–235 mm). Color in life: dorsum uniformly plain gray or purplish gray, ventrum whitish.

Syntypes of A. acrocephalus (ZMA 11.090, 193 mm, and ZMA 11.088, 2: 75–91 mm) are practically identical in all respects with specimens of comparable size from the Fly. The holotype of A. digulensis (520 mm total length) has the pronounced nuchal hump and deep dorsomedian depression of the snout characteristic of large A. acrocephalus. Han Nijssen has kindly compared it with my 447-mm specimen from the Fly (ZMA 115.537) and finds that they belong to the same species.

Arius acrocephalus is perhaps most closely related to the poorly known Arius latirostris Macleay, 1884, the only Arius species of southern New Guinea rivers that has not been positively or tentatively identified from the Fly. Macleay did not designate a holotype. The statement “length, 20 inches” (Macleay, 1884: 278) implies but does not prove that he had only a single specimen. I have examined four specimens from Goldie River, the type-locality, deposited in the Australian Museum, Sydney. Three of these specimens, I.9072–9074, 456–462 mm, are cataloged as syntypes; they are all substantially more than 20 inches in total length and less than that in standard length. The fourth specimen, I.13398, 312 mm, clearly belongs to the same species. Arius latirostris is moderately broad headed and broad mouthed; snout slightly pointed; barbels moderately long, maxillary barbel reaching posteriorly beyond base of pectoral fin spine. Oral tooth bands similar in size and shape to those of A. acrocephalus (see Figure 20b); tooth band of upper jaw partially exposed when mouth is closed (possibly due to poor preservation). Eyes lateral, 23–29. Gill rakers on first gill arch 15–17; posterior face of second gill arch with 0–4 + 0 gill rakers; upper limb of second gill arch with a thick lobe. Dorsal profile of head straight: snout without pronounced median depression or browlike ridges, nuchal hump absent. Basal portion of occipital process of head shield about twice as wide as in A. acrocephalus. Pectoral fin with 11 segmented rays. Anal fin pterygiophores 19(1). Free vertebral centra posterior to Weberian apparatus 46(2). Abdomen with small, widely scattered melanophores (absent in Fly Arius). Berra et al. (1975) identified numerous recently collected specimens from the Laloki (= Goeldi) River as A. latirostris; I have examined the lots that were deposited in the Smithsonian (USNM 210752, 210801, 210832, 210840, 210851, and 210858) and find they are A. acrocephalus.

The broad-snouted catfish (Neoarius latirostris) is a species of catfish in the family Ariidae. It was described by William John Macleay in 1883, originally under the genus Arius. It inhabits freshwater rivers in Indonesia and Papua New Guinea. Its diet includes finfish, mollusks, prawns, terrestrial arthropods, aquatic insects, and plants. It reaches a maximum standard length of 50 cm (20 in).

The IUCN redlist currently lists the broad-snouted catfish as Least Concern, but makes note of a present decline in the species' population. It cites fishing/harvesting, mining, quarrying, and residential developments as the main threats to the species.