Phenacorhamdia tenebrosa (Schubart, 1964)

Giorgis, Pablo, Ciotek, Liliana, Almirón, Adriana & Casciotta, Jorge, 2012, First record of Phenacorhamdia tenebrosa (Schubart, 1964) (Siluriformes, Heptapteridae) from the Paraná river basin in Argentina., Ichthyological Contributions of PecesCriollos 24, pp. 1-4 : 2

Phenacorhamdia tenebrosa :

AI 308, 4 ex., 29.4-44.7 mm SL, Argentina, Corrientes province, Paraná river at Ituzaingó (27°30'04.3''S- 56°42'41.6''W), coll: L. Cardinale, November, 2007 MACN-ict 9763, 1 ex., 41.5 mm SL, Argentina, Entre Ríos province, Pre-Delta National Park , Paraná river basin, arroyo La Azotea, Tapera de Chano (32º07'21.5"S - 60º37'58.9"W). coll: P. Giorgis & L. Ciotek

Description

This species can reach 86.4 mm TL (Graça & Pavanelli 2007). Morphometric characters are provided in table 1 . Body elongate and slender. Head short (four to five times in SL), depressed, and dorsally covered by thin skin. Eyes small, placed dorsally on head. Anterior nares tubular. Mouth gape terminal, slightly superior. Lower jaw a bit longer than upper jaw, with irregular rows of minute conical teeth. Maxillary barbells surpassing distal border of pectoral fin. Bases of outer and inner mental barbells in a straight line; outer ones reaching pectoral-fin origin, inner ones extended to distal margin of opercular membrane. Dorsal-fin origin nearer snout tip than caudal-fin base. Adipose fin 5.2-5.9 times in SL, its origin placed behind the vertical through anal-fin origin. Caudal fin deeply forked, lower lobe slightly longer than the upper one. Dorsal fin with a weak spine and 6 branched rays, pectoral fin with 8 and pelvic fin with 6 rays. Distal margin of anal fin rounded, with 11 or 12 rays.

Color in life

Ground color of body and head at dorsum and sides brownish, ventrally pale. Head and body at dorsum covered by minutes and numerous dark brown melanophores. Barbells and rays of all fins pigmented as body. Interradial membranes hyaline ( Fig. 1 ).

Habitat

The specimen collected in the arroyo La Azotea, Pre-Delta National Park was found in small muddy pool originated in the floodplain of the Paraná river when the water begins to decline after the flood ( Fig. 2 ).

Distribution

This species was known from the upper Paraná and São Francisco river basins in Brazil. The specimens examined herein come from the Paraná river at Yaciretá dam close to Ituzaingó city and arroyo La Azotea in Pre-Delta National Park ( Fig. 3 ).

Figures

Fig. 1. Lateral view of Phenacorhamdia tenebrosa, in life.

Fig. 2. Arroyo La Azotea, Tapera de Chano in Pre-Delta National Park, the southernmost locality where Phenacorhamdia tenebrosa was collected.

Fig. 3. Map showing the collecting sites (light blue stars) of Phenacorhamdia tenebrosa in the Paraná river, Argentina.