Trichomycterus igobi

discussion

Remarks: Valid as Cambeva igobi (Wosiacki & de Pinna 2008) (see Katz et al., 2018).

Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil

biology_ecology

Ecological data. Specimens of Trichomycterus igobi were collected in the same general locality as T. sp. C in the rio Jordão, and presumably occupy the same kind of fast water, rocky-substrate environment reported for that species (cf. Wosiacki & de Pinna, in press). The details of its microhabitat, however, are as yet unknown. The stomach of the cleared and stained specimen contained larvae of Diptera (Simulidae), Ephemeroptera, and Trichoptera, indicating benthic feeding habits.

Trichomycterus igobi, a new catfish species from the rio Iguaçu drainage: the largest head in Trichomycteridae (Siluriformes: Trichomycteridae)

description

Description. Morphometric data for holotype and paratypes given in Table 1. Body short, rounded at level of pectoral girdle and gradually more compressed posteriorly. Dorsal profile of trunk straight or slightly convex, ventral profile gently convex. Dorsal and ventral profiles of caudal peduncle slightly convex. Integument thick and opaque, especially over dorsal-, anal- and pectoral-fin bases. Small papillae visible under stereomicroscope over surface of body; papillae larger and more densely concentrated over oral surface of lips. Head large, longer than wide, depressed. Head width larger than maximum body width. Snout broad, convex in dorsal view. Dorsal profile of head straight in lateral view; ventral profile slightly convex. Interorbital region flat. Lateral portion of head swollen by well-developed jaw muscles. Eyes round, dorso-laterally oriented, slightly converging anteriorly towards midline. Orbital rim not free. Skin covering eye thin and transparent. Anterior nostrils smaller than eye, separated by space approximately equal to interorbital, surrounded by fleshy flap of integument posterolaterally continuous with nasal barbel. Posterior nostrils smaller and more closel

Trichomycterus igobi, a new catfish species from the rio Iguaçu drainage: the largest head in Trichomycteridae (Siluriformes: Trichomycteridae)

diagnosis

Diagnosis. Trichomycterus igobi is distinguishable from all other species currently in Trichomycterus by its large head (23.8 - 26.8 % SL), which is proportionally the largest head in any Trichomycteridae. Other diagnostic features that distinguish the new species from most or all of its congeners include an almost entirely cartilaginous second hypobranchial (with only vestigial ossification); a mesially expanded palatine ossification; a narrow cleithrum, falciform in shape; and the lack of a proximal posterior concavity on the third ceratobranchial. The rigid spine-like morphology of individual procurrent rays of the caudal fin, the extension of the dorsal caudal-fin procurrent ray series (extending for ten neural spine tips), and the presence of ten or eleven branchiostegal rays each distinguish T. igobi from all congeners except T. stawiarski and T. sp. C (see Discussion). Other characters shared with various other species of Trichomycterus yet useful for identification include a dorsal fin located on a concavity on dorsal profile of trunk; the short caudal peduncle (15.4 - 19.7 % SL); and the first anal-fin ray base posterior to the vertical through the base of the last dorsal-

Trichomycterus igobi, a new catfish species from the rio Iguaçu drainage: the largest head in Trichomycteridae (Siluriformes: Trichomycteridae)