Ituglanis boitata

description

Description. Morphometric data in Table 1. Body elongate, trunk roughly cylindrical, gradually compressed towards caudal fin. Dorsal profile of trunk convex along anterior half then straight to insertion of dorsal fin. Ventral profile of trunk straight to slightly convex. Dorsal and ventral profile of caudal peduncle straight or with posterior portion deeper. Head depressed, trapezoidal from dorsal view, wider posteriorly. Dorsal profile straight and ventral profile straight to slightly convex. Snout straight to slightly round from dorsal view. Eyes located in posterior region of head just behind posterior nostril, dorsally oriented but also visible from lateral view; orbital rim not free, eyes covered with skin thin and transparent. Nostrils slightly smaller than eye diameter. Anterior nostril surrounded by fleshy flap of integument posterolaterally continuous with nasal barbel. Posterior nostril surrounded anterolaterally by thin flap of integument. Gill openings not constricted but united with isthmus anteriorly forming free fold. Mouth subterminal straight or with corners slightly oriented posteriorly. Lower lip with a pair of conspicuous fleshy lobes located medially to origin

A new species of Ituglanis Costa & Bockmann, 1993 (Siluriformes: Trichomycteridae) endemic to the Tramandaí – Mampituba ecoregion, southern Brazil

diagnosis

Diagnosis. Ituglanis boitata is distinguished from congeners with the exception of I. bambui Bichuette & Trajano; I. boticario Rizzato & Bichuette; I. paraguassuensis Campos-Paiva & Costa and I. proops (Miranda Ribeiro) by the supraorbital canal of the cephalic laterosensory system interrupted between nasal and frontal sections and the presence of pore s 2 [Fig. 2; vs. supraorbital canal uninterrupted and pore s 2 absent (presence of pore s 2 is variable in I. bambui; Datovo pers. comm.)]. Ituglanis boitata differs from I. bambui, I. boticario, I. paraguassuensis and I. proops in the larger number of vertebrae (41 – 42 vs. less than 40 vertebrae). Ituglanis boitata is further distinguished from I. bambui, I. boticario and I. paraguassuensis by the anterior cranial fontanel drop-shaped slightly larger than the posterior fontanel (Fig. 2; vs. the anterior cranial fontanel absent in I. bambui and I. boticario; elongated, distinctly larger than the posterior fontanel in I. paraguassuensis). Ituglanis boitata is further distinguished from I. boticario and I. paraguassuensis in body coloration (Fig. 1; the lateral surface of body with small dark brown blotches equivalent to eye circumfer

A new species of Ituglanis Costa & Bockmann, 1993 (Siluriformes: Trichomycteridae) endemic to the Tramandaí – Mampituba ecoregion, southern Brazil

discussion

Remarks. Even though the external aspect of Ituglanis boitata and I. proops are very similar, some differences are readily remarkable. These species differ in the number of branched dorsal-fin rays — modally seven in I. boitata (observed in 40 of 45 analyzed specimens) vs. modally six in I. proops (observed in 23 of 24 analyzed specimens); and in the interopercular patch of odontodes length (Fig. 4; 22.7 – 31.4 vs. 35.2 – 43.1 mm of HL, respectively). De Pinna & Keith (2003) have already highlighted the large interopercular plate in I proops as “ the largest interopercular patch of odontodes in the genus ” and stated that “ (…) the dorsoposterior margin of the interopercular patch closely approaches the ventral margin of the opercular one ”. Subsequently, the unusual interopercular patch of I proops was illustrated and cited as “ clearly more elongate than those of many other trichomycterines ” by Datovo & Bockmann (2010: fig. 38 a).

A new species of Ituglanis Costa & Bockmann, 1993 (Siluriformes: Trichomycteridae) endemic to the Tramandaí – Mampituba ecoregion, southern Brazil

distribution

Distribution and ecological notes. Ituglanis boitata is endemic to the Tramandaí – Mampituba ecoregion sensu Abell et al. (2008). This area includes three small freshwater drainages (Fig. 6; the rio Araranguá, rio Mampituba and rio Tramandaí basins) draining from the “ Serra Geral ” into the coastal plain in Northeastern Rio Grande do Sul and Southeastern Santa Catarina States, southern Brazil. The rio Araranguá and rio Mampituba flows directly into the sea while the rio Tramandaí basin is composed by two main rivers draining the Serra Geral (the rio Três Forquilhas and rio Maquiné) that flows to two large lagoons in the coastal plain. These lagoons are interconnected with a series of smaller lagoons, all flowing to the sea through an estuary known as rio Tramandaí. Ituglanis boitata is usually found associated with clear water, rocky bottom, and small currents streams and rivers in the middle and upper portions of these drainages (Fig. 7) and has never been collected in lagoons or surroundings swamps of the coastal plain. An area of fish endemism including the rio Maquiné, rio Três Forquilhas and rio Mampituba basins was first mentioned by Malabarba & Isaia (1992). Later, Reis & S

A new species of Ituglanis Costa & Bockmann, 1993 (Siluriformes: Trichomycteridae) endemic to the Tramandaí – Mampituba ecoregion, southern Brazil