Ituglanis mambai, Bichuette & Trajano, 2008

Bichuette, Maria Elina & Trajano, Eleonora, 2008, Ituglanis mambai, a new subterranean catfish from a karst area of Central Brazil, rio Tocantins basin (Siluriformes: Trichomycteridae), Neotropical Ichthyology 6 (1), pp. 9-9 : 9-

Ituglanis mambai , new species

Fig. 2

Holotype. MCP 42538, 53.4 mm SL, Brazil, northeastern State of Goiás, Posse County, Lapa do Sumidouro Cave (14º19’21.0"S 46º14’41.0"W, elevation 792 m), upper rio Tocantins basin; M. E. Bichuette & S. Secutti col., 31 Mar 2007.

Paratypes. LISDEBE 2047, 6, 32.6-65.4 mm SL (C&S); same locality as holotype; M. E. Bichuette, E. Trajano & A. C. Barbosa col., 1 Sep 2004. MCP 42537, 3 , 38.7-59.5 mm SL, same locality as holotype; M. E. Bichuette, E. Trajano & A. C. Barbosa col., 1 Sep 2004. MZUSP 94719 , 4 , 26.7-66.1 mm SL; same locality as holotype; M. E. Bichuette, E. Trajano & S. Secutti col., 31 March 2007 .

Diagnosis. Ituglanis mambai is distinguished from both epigean ( I. cahyensis , I. laticeps , I. macunaima , I. metae , I. nebulosus , I. parahybae and I. proops ) and cave congeners ( I. bambui , I. epikarsticus , I. passensis and I. ramiroi ) by the combination of the following characteristics: posterior fontanel absent (except for I. epikarsticus and I. macunaima ); pectoral-fin rays usually i,7 (except for I. bambui , I. passensis and I. epikarsticus ); six pleural ribs (except for I. bambui , I. parahybae and I. ramiroi ); total vertebrae 37-38 behind Weberian apparatus (except for I. bambui , I. laticeps and I. macunaima ,); shorter predorsal length (65.1-70.8% in SL) (except when compared to I. bambui ); shorter caudal peduncle (8.4-11.9% in SL); shorter dorsal-fin base (7.7-11.3% in SL); larger interobital width (29.2-36.5% in HL) (except to the cave species); wider mouth (43.4-64.0% in HL) (except for I. bambui ); pigmentation intermediary between epigean and cave Ituglanis species, composed by irregular light brown spots along the body; eyes size variable and intermediate between those of epigean and formerly described cave-restricted congeners, with a diameter varying, in adults, from 0.5 to 1.0 mm (7.8-10.1 % in HL) (except for I. cahyensis – 7.0- 8.1 % in HL). Additional diagnostic character states: the maxillae with a discrete medial-posterior projection; fronto-lacrimal one half-length of the maxillae and pointed backwards; posterior process of palatine half its length, with a tenuous medial concavity; 14 dorsal and 12 ventral procurrent rays.

Description. Morphometric and meristic data of holotype and paratypes given in Table 1. Body elongate, semi-cylindrical, becoming compressed toward caudal fin. Dorsal and ventral profiles of body, and caudal peduncle straight ( Fig. 2a ). Lips and barbels covered by papillae.

Head relatively wide and depressed, rounded in dorsal view. Eyes reduced in relation to epigean Ituglanis species, visible externally as round black spots, covered by thin skin ( Fig. 2b ). Anterior nostril transversally ovoid and slightly smaller than posterior one, surrounded laterally by nasal barbels. Posterior nostril rounded, surrounded anteriorly by thin flap of integument. Mouth subterminal, rictus laterally directed. When adpressed to body, maxillary barbel extending to middle of adpressed pectoral fin; submaxillary and nasal barbels extending to origin of pectoral fin.

Pectoral fin i,7, triangular in dorsal view, first ray longer, unbranched and filamentous. Dorsal fin ii,7, rectangular in lateral view. Anal fin i,5, semi-circular in lateral view, distal margin slightly rounded. Pelvic fin i,4, rectangular in ventral view. Margin of caudal fin straight, with 13 principal rays (7 in the upper and 6 in the lower lobe), 14 dorsal and 12 ventral procurrent rays.

General morphology of cranium: main body axis of mesethmoid with anterior width larger than posterior width, width of cornua 3/4 of its lenght, cornua with rounded distal extremity; posttemporosupracleithrum of medium size, with dorsal limb lying on pterotic. Two premaxillary tooth rows. Maxillae with discrete medial-posterior projection; fronto-lacrimal one half-length of maxillae and pointed backwards. Six branchiostegal rays. Base of laminar surface of urohyal four times longer than its distal extremity; urohyal dorsal process short. Length of posterior process of palatine half total palatine length, medial concavity tenuous. Vomer arrow-shaped with long posterior process. Opercle with 14-16 odontodes and interopercle with 24-26 odontodes.

Postcranial skeleton. Total vertebrae 37-38 behind Weberian apparatus, six pairs of ribs. Epural absent. Neural 12 A new subterranean trichomycterid catfish from rio Tocantins basin

spine (n = 1) of preural centrum with round tip. Upper hypural plate triangular, lower hypural plate trapezoidal. Uroneural with acute distal extremity.

Color in alcohol. Pale yellowish to light brown in adults and pale yellowish in juveniles, with irregular light brown spots in lateral and dorsal views ( Figs. 2a and 2b ). Eye black. Fins poorly pigmented, showing translucent aspect in those individuals with pale pigmentation. Dorsal portion of head light brown.

Color in life. Body in general pale yellowish, irregular light brown spots along dorsum and flanks of body. Eyes black. Dorsal portion of head darker than rest of body. Juveniles less pigmented than adults, dorsal region of skull darker.

Distribution. Ituglanis mambai is known from a single subterranean stream inside the Lapa do Sumidouro Cave. This stream reach at least 500 m of extension.

Etymology. The specific name makes reference to the karst region, Mambaí, where the species occurs.

Notes on ecology and behaviour. Ituglanis mambai inhabits a subterranean stream inside the Lapa do Sumidouro Cave. The stream reach where the fishes were observed is characterized by slow to fast-moving waters, 10-90 cm deep on average, and bottom formed basically by sand, silt, some gravels and boulders. Visual censuses, carried out in two occasions and covering an area approximately 300 m long and 1.5 m wide, resulted in minimum population densities varying from 0.12 inds. m-2 (September 2004, end of the dry season) to 0.04 inds. m-2 (April 2007, beginning of the dry season). Environmental variables measured in September 2004: water temperature, 23.4°C; pH, 7.9; conductivity, 0.141 mSm. cm-1; dissolved 13 paratypes of Ituglanis mambai . SD, standard deviation. oxygen, 7.4 mg. l-1.All observed individuals were solitary, with swimming activity on the bottom and sometimes in the midwater. In the natural habitat, I. mambai catfish displayed cryptobiotic habits, trying to hide into the gravels and under boulders when disturbed, apparently showing a negative response to carbide and flashlight. It was observed a preference to slow-moving pools. Recent flood marks were observed

M. E. Bichuette & E. Trajano 13

in the base-level stream conduit in March/ April 2007 (end of rainy season), when less individuals were observed along the 300 m reach inspected, when compared to September 2004. The average condition factor for 12 individuals of I. mambai captured at the end of the dry season (September 2004) was 2.1, showing, for two juvenile individuals (33.0 and 35.9 mm SL), values of 0.5, and varying from 0.7 to 3.4, for adults (40.2- 72.0 mmSL).

Figures

Fig. 2. Ituglanis mambai, holotype, MCP 42538, 53.4 mm SL. Lapa do Sumidouro Cave, Posse, Goiás, Brazil. Lateral (above) and dorsal (below) views.