Trichomycterus maracaya

biology_ecology

Natural history notes. Trichomycterus maracaya was found along a stretch of about 400 m of a streamlet 60 - 210 cm wide with maximum depth about 140 cm running through a semi-deciduous gallery forest (Fig. 10). The streamlet runs through a yellowish limonite (iron hydroxide) rocky bed with pebbles and sand, and several pools with muddy bottom and accumulated plant litter and fine sediment. Small individuals (up to 32.5 mm SL) were found among submerged roots near the bank as well as buried in plant litter in small pools 30 - 50 cm deep. Larger individuals (up to 51.3 mm SL), in contrast, were found only among plant litter in larger pools up to 100 cm deep. Trichomycterus maracaya was the only fish species recorded in the streamlet, along with the tadpoles of three species of stream-dwelling frogs. The fishes were active at dawn and night, foraging on the exposed areas of the stream bed and on the leaf litter. One large individual (about 50 mm SL) was observed at early night swallowing tail-first a young, leaf litter-dwelling tadpole of the glass frog Hyalinobatrachium sp. (Centrolenidae). Four other individuals (45.6 - 51.3 mm SL) regurgitated young tadpoles of the same frog specie

Trichomycterus maracaya, a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the T. brasiliensis species-complex

description

Description. Morphometric data for type series presented in Table 1. Dorsal profile of body sloped from tip of snout to anterior portion of trunk and approximately straight from that point to baseofcaudalfin (Figs. 1 - 3). Convexityoftrunkmorepronounced in larger individuals. Ventral body profile approximately straight to slightly convex from mouth to insertion of pelvic fin; slightly concave from end of base of pelvic fin to caudal fin. Crosssection of body in trunk region approximately oval, becoming gradually more compressed transversely posterior to base of dorsal fin. Caudal peduncle strongly compressed. Axillary gland with small pore. Urogenital and anal openings on vertical through base of first or second branched dorsal-fin rays. Head wide and depressed, slightly longer than broad (Fig. 4). Eyes small, orbital rim not free except for discrete ventral invagination. Skin covering eye thin and translucent. Anterior nostril small, surrounded by fleshy tube-shaped flap of integument. Posterior nostril located approximately midway between anterior nostril and anterior orbital rim, and surrounded by raised fleshy flap, except posteriorly. Mouth inferior. Lower lip with conspicuous

Trichomycterus maracaya, a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the T. brasiliensis species-complex

diagnosis

Diagnosis. Trichomycterus maracaya, along with T. brasiliensis, T. iheringi (Eigenmann), T. mimonha Costa, T. potschi, and T. vermiculatus, are members of the Trichomycterus brasiliensis species-complex, based on the possession of the following apomorphic characters unique in Trichomycterus: four longitudinal rows of well-defined blotches formed by very dense concentration of dark chromatophores in the deeper layer of skin (vs. four rows faint, with limits of blotches poorly-defined); and pectoral fin with I + 5 - 6 rays (vs. usually I + 7 - 8). Members of this putative clade (except for T. iheringi) may be further distinguished from other species of Trichomycterus in having the bases of the pelvic fins very close to each other, sometimes in contact (vs. the pelvic – fin bases very spaced). Additionally, T. maracaya differs from the remaining species of Trichomycterus (except T. brasiliensis and T. potschi) in retaining the primordial epiphyseal cartilaginous bar separating the anterior and posterior cranial fontanels even in larger individuals (vs. having the osseous epiphyseal bar separating the anterior and posterior cranial fontanels appearing early in the ontogeny). Furthermor

Trichomycterus maracaya, a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the T. brasiliensis species-complex

distribution

Distribution. Known only from an unnamed streamlet running along the foothill of the Morro do Ferro, município de Poços de Caldas (Fig. 9), State of Minas Gerais, southeastern Brazil [see Bonotto (1994) for figures of the Morro do Ferro area]. The streamlet is a tributary of the rio Pardo system (upper rio Paraná).

Trichomycterus maracaya, a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the T. brasiliensis species-complex