Pterobunocephalus depressus (Haseman, 1911)

Ciotek, Liliana, Giorgis, Pablo, Casciotta, Jorge, Pterobunocephalus, Adriana Almirón Abstract, Park, Pre-Delta National, The, Argentina. & Azotea, La, 2008, Presence of Pterobunocephalus depressus (Haseman, 1911) (Siluriformes, Aspredinidae) in freshwaters of Argentina., Ichthyological Contributions of PecesCriollos 9, pp. 1-4 : 1-3

Pterobunocephalus depressus (Haseman, 1911)

Material examined

Pterobunocephalus depressus : AI 236, 3 ex., 34.4-52.5 mm SL, Argentina, Entre Ríos province, Pre-Delta National Park, río Paraná basin, arroyo La Azotea , 32°07’17.8”S - 60°38’04.3”W. coll: L. Ciotek and P. Giorgis, April 2007 .

Description

This species can reach 80 mm of SL. Morphometry of the three specimens of P. depressus are provided in table 1. Body elongated and very depressed, depth 9.2 to 11.9 times in SL. Caudal peduncle slightly compressed and narrow. Body with papillae forming longitudinal and parallel lines on caudal peduncle; one line on the dorsum and five on each side. Head depressed bearing low ridges, covered with papillae especially on ridges and anterior nostrils. Eyes small and dorsal. Mouth small and terminal; patches of viliform teeth in both jaws. Maxillary barbels reaching or surpassing the pectoral fin base origin. Mental barbels reaching or surpassing the post-mental ones. Ventrally, the coracoid processes are very short, less than three times in the distance between their tips. Dorsal fin with 5 rays, its origin is nearer snout tip than caudal fin base. Six pectoral fin rays, pectoral spine with strong serrae on anterior and posterior edges. Anal fin with 11 rays.

Colour in life

Ground colour dark brown ( Fig. 1 ). Head and anterior region of the body pale brown. Caudal peduncle dark brown with three pale brown transverse bars, the first one just behind the dorsal fin, the second one about half length of caudal peduncle and the third one at the caudal fin base. Pectoral and pelvic fins pale brown with scattered chromatophores on their margins. The remaining fins, dark brown with their distal tips hyaline.

Behaviour in aquarium

Most of the time P. depressus is found on the bottom, however sometimes they can be seen feeding among the floating plant roots. When the fish want to return to the bottom, they just passively glide down in a zig-zag movement, like a leaf falling from a tree.

Distribution

Pterobunocephalus depressus (Haseman, 1911) seems to have a wide distribution that includes Amazon, Orinoco and Paraguay river basins ( Friel, 2003; Ferraris, 2007). The specimens of this species considered herein was found in the arroyo La Azotea, 32°07’17.8”S - 60°38’04.3”W, río Paraná basin, Entre Ríos province, Pre-Delta National Park ( Figs. 2 , 3 )

Figures

Fig.1. Dorsal view of an alive specimen of Pterobunocephalus depressus.

Fig. 2. Arroyo La Azotea in Pre-Delta National Park, where Pterobunocephalus depressus was collected.

Fig. 3. Map showing the collecting site of P. depressus.