Ituglanis agreste, Lima & Neves & Campos-Paiva, 2013

Lima, Sergio M. Q., Neves, Cinara P. & Campos-Paiva, Rafael M., 2013, Ituglanis agreste, a new catfish from the rio de Contas basin, northeastern Brazil (Siluriformes: Trichomycteridae), Neotropical Ichthyology 11 (3), pp. 513-524 : 514-518

Ituglanis agreste , new species

Fig. 1

Holotype. MNRJ 40196 , 40.5 mm SL, Brazil, Bahia, municipality of Boa Nova; rio de Contas basin, rio Gongogi drainage, rio Tarugo , tributary of rio Uruba , 14º22’08.95”S 40º11’45.33”W, 09 Jul 2008, S. M. Q. Lima, R. M. Campos-Paiva, P. Hollanda Carvalho & H. Lazzarotto.

Paratypes. MNRJ 40197 , 5 , 32.4-40.8 mm SL; UFBA 7134, 5 , 33.4-41.7 mm SL; UFRN 29, 6 , 32.8-41.9 mm SL (3 c&s), all collected with holotype . MZUSP 102535 , 6 ., 38.4-44.1 mm SL, same locality as holotype , 10 Feb 2009, S. M. Q. Lima, R. M. Campos-Paiva, P. Hollanda Carvalho & D. F. Almeida .

Diagnosis. Ituglanis agreste is distinguished from all species of the genus, except I. paraguassuensis by the reduced number of vertebrae 36 (vs. 38 or more in all other Ituglanis , except in I. paraguassuensis , I. nebulosus , I. bambui , I. epikarsticus , I. ramiroi , and I. passensis ; unknown for I. guayaberensis ); number of ribs (5-6) (vs. 2 or 3 in I. amazonicus , I. eichorniarum , I. gracilior , I. ina , I. macunaima , I. nebulosus , and I. parkoi ; 4 in I. laticeps and I. cahyensis ; 7 in I. passensis ); number of pectoral-fin rays i,6 (vs. i, 4 in I. cahyensis , I. macunaima , and I. parahybae ; i, 5 in I. amazonicus , I. eichorniarum , I. metae , and I. nebulosus ; i, 7 in I. bambui , I. epikarsticus , I. mambai , I. passensis ; iii, 5 in I. guayaberensis ; i, 8 in I. ramiroi ); and skin covered by irregular brown blotches (vs. distinct color pattern in all other Ituglanis ; absence in I. ina and the subterranean species, I. bambui , I. passensis , I. epikarsticus , and I. ramiroi ).

Ituglanis agreste is also easily distinguished from the subterranean species by large eyes (vs. minute eyes) and intense pigmentation (vs. pigmentation absent or almost lack).

Ituglanis agreste is distinguished from I. paraguassuensis , its geographically closest species, by a higher number of odontodes in an elongate interopercle patch (26-30) (vs. reduced with 14-15 odontodes); seven branchiostegal rays (vs. 8) and pore s1 lacking (vs. s1 present).

Description. Morphometric data for holotype and paratypes are given in Table 1. Body elongated, subcylindrical about to dorsal-fin origin, and gradually compressed in caudal peduncle. Dorsal and ventral side view straights, except in dorsal part of the head, which is slightly convex. Head depressed, longer than wide, rounded in dorsal view. Eyes rounded and small, without free orbital margin, covered by a thin translucid membrane, lightly located on anterior half of head. Barbels and head covered by minute papillae. Mouth subterminal. Tip of nasal barbel reaching posterior edge of opercular patch of odontodes; tip of maxillary barbel reaching pectoral-fin base and tip of rictal barbel reaching posterior edge of interopercular patch of odontodes or the anterior edge of pectoral-fin.

Total vertebrae 36, 12-13 precaudal and 23-24 caudal. Ribs 5 (2) or 6 (1). Origin of dorsal-fin in a vertical through the 22nd vertebra. Origin of anal-fin in a vertical through the 23 rd vertebra and through the base of the 7 th ray of dorsal fin. Origin of pelvic fin in a vertical through the 17 th- 18 th vertebra. Pectoral-fin rays i,6, pectoral fin triangular, first ray simple and pectoral filament absent (holotype plus one specimen) or ranging from 5-25% (16) greater than the other rays of the pectoral fin. Pelvic-fin rays 5 (i,4). End of pelvic fin overreach the urogenital papilla. Dorsal-fin rays 11-12 (v-vi,6), anal-fin rays 10-11 (v-vi,5). Principal caudal-fin rays 13 (i,11,i), procurrent dorsal rays 13 (2) or14 (1) and ventral 10 (2) or14 (1). Caudal fin subtruncate.

Mesethmoid with the anterior portion and shaft nearly straight, gradually tapering at proximal tip ( Fig. 2a ). Lateral ethmoid without lateral projections. Anterior fontanel restricted to small pit with small enlargement in posterior third of frontals. Posterior fontanel as small round opening on posterior portion of parieto-supraoccipital. Sesamoid supraorbital elongate, slender and curved, without lateral process, slightly longer than autopalatine; sphenoticprootic-pterosphenoid narrow, with anterior portion anteriorly directed ( Fig. 2a ). Pterotic with posterolateral projection.

Autopalatine with a deep concavity on the internal medial border; posterior process moderate, about 50% of the length of the autopalatine ( Fig. 2a ). Posttemporosupracleithrum with anterior and posterior processes. Vomer arrow-shaped, with thin lateral projections and long posterior process ( Fig. 2b ). Parasphenoid with two anterior and one posterior processes. Weberian capsule fused to basioccipital and exoccipital and with small lateral opening on each side. Premaxilla trapezoidal and curved with two rows of conical teeth. Maxilla curved with developed ventral process, smaller than premaxilla ( Fig. 2a ). Dentary almost straight with two regular rows of conical teeth and with pronounced coronoid process ( Fig. 3 ).

Hyomandibula with an anterior laminar projection, a deep depression in dorsolateral portion and pores on anterior and dorsomedian regions ( Fig. 4 ). Anterior portion of quadrate laminar and pronounced. Metapterygoid large, laminar and somewhat trapezoidal, articulating to quadrate by a cartilaginous block and to hyomandibula by bone contact area. Interopercular plate broad and elongate bearing conspicuous posterior projection, with 26- 30 odontodes placed in two rows, including in anteroventral projection ( Fig. 4 ). Opercle with 16-17 odontodes. Odontodes conical, curved on the opercular patch of odontodes and thinner on interopercular patch of odontodes.

Parurohyal with conspicuous central foramen and lateral process laminar and elongated, gradually tapering from base to tip, with about same length of ceratohyal ( Fig. 5 ). Ventral hypohyal with deep depressions for articulation with parurohyal condyles. Seven branchiostegal rays.

First basibranchial absent, second and third basibranchials ossified with anterior and posterior cartilaginous tips; and fourth basibranchial consisting of elongated, flattened and rounded cartilage ( Fig. 6 ). First hypobranchial 1 ossified and stem-like; second elongate somewhat trapezoidal, mostly cartilaginous except for anterolateral process; third flattened cartilaginous with ossified anterolateral process. First, second, third, and fourth ceratobranchials ossified with cartilaginous tips, and with posterolateral laminar expansions; fifth one curved with small teeth on anterior half. First epibranchial with long anterior process; second with two small alternated process; third with one rounded posterior process; fourth flattened, somewhat rectangular; fifth absent or not evident. First and second pharyngobranchials absent; third and fourth stem-like, this last attached to tooth plate. Upper pharyngeal tooth plate with conical teeth arranged in two rows in ventromedial region ( Fig. 6 ).

Cleithrum flatenned, curved and slightly triangular. Scapulocoracoid trapezoidal, ossified with cartilaginous tip ( Fig. 7 ). Pelvic girdle slender and mostly ossified, with cartilage restricted to posteromedial margins ( Fig. 8 ).

Upper caudal plates composed of pleurostyle and hypural plates (hypurals 3-5) fused in a single triangular element (1), or with hypural 3 and hypurals 4-5 not fused (2) ( Fig. 9 ). Parhypural partially fused to hypurals 1-2, with distal portion forming a spine-like structure ( Fig. 9 ).

Cephalic sensory and lateral line channels composed by simple tubes ending in single pore, continuous and interconnected on pterotic, sphenotic-prooticpterosphenoid, and lateral border of frontals. All cephalic pores paired (18): supraorbital 2-3 (s2, s3, and s6; one specimen with s2 absent), infraorbital 4-5 (i1, i3, i10, and i11; one specimen with i9), preopercular 1 and lateral line 3 (ll1, ll2, and ll3).

Coloration. Body with diffuse and irregular blotches on yellow background. Chromatophores more concentrated in dorsal and lateral region of body, forming large and irregular blotches. In lateral region, chromatophores less concentrated and blotches more dispersed. Ventral region spotless from isthmus to pelvic-fin base, region posterior to pelvic fin with diffuse, irregular and scattered blotches. Caudal penducle with smaller irregular blotches, but more defined. Chromatophores more concentrated in dorsolateral region of head and opercular patch of odontodes. Nasal, maxillary, and rictal barbels with chromatophores irregularly distributed throughout its entire length. Ventral region of head with chromatophores forming conspicuous spot on lower lip and with irregular and scattered blotches in anterior region to isthmus and interopercle ( Fig. 1c ). Fins with few chromatophores, more often at base of these. Some individuals exhibit lighter color than others, but following same color pattern.

Distribution. Ituglanis agreste is only known from the type locality, in rio Tarugo, municipality of Boa Nova, Bahia, northeastern Brazil. This river is a tributary of the rio Uruba, that flows into rio Gongogi, principal drainage of right margin on the middle section of rio de Contas basin ( Fig. 10 ). This is the transition zone of the Serra da Ouricana, where small remnants of a formerly extensive humid forest that delineates the limits of the Atlantic Forest domain in the region ( Gonzaga et al., 1995). Just a few kilometers to the west, the landscape gives way to the semi-arid Caatinga region, typically known for regular droughts. Thus, it is possible that the rio Tarugo represents the western geographical limit of distribution for this species. During a two year sampling (2008 - 2009) along a 325 km transect of the rio de Contas (between the municipalities of Ibuaçussê and Uruçuca), Ituglanis agreste was found only at one site.

Etymology. The specific name “agreste ” (from latim agrestis, which means relative to land, field, wild, or rustic) refers to a semi-humid narrow strip parallel to the coast in northeastern Brazil, encompassing the area between the Rio Grande do Norte State to the middle section of rio de Contas basin in Bahia State ( Forattini et al., 1981), that marks the transition between two distinct biomes, the Atlantic Forest and the semi-arid Caatinga ( Prado, 2003), where the new species was discovered. A noun in apposition.

Ecological notes. Ituglanis agreste was found along a stretch of about 200 m in a mid-small size river with width up to 8 m, in a moderate slope with clear and cold water, with transparency of about 2 m ( Fig. 7 ). The water flow was mainly turbulent, with alternating areas of currents and pools, though a predominance of moderate to strong drifts. Substrate consists of rocks or sand. The most common depth observed was about 0.5 m, but some parts had about 1.7 m. Some sites had underwater aquatic macrophytes and riparian vegetation. The backwaters area had vegetation composed of Typha sp. The margins were deforested and the environment was mainly composed of pastures. A reservoir without a lake formed by the dam of the river was observed above the collection site. Other species collected with Ituglanis agreste were: Astyanax bimaculatus (Linnaeus) , Callichthys callichthys (Linnaeus) , Geophagus brasiliensis (Quoy & Gaimard) , Rhamdia quelen (Quoy & Gaimard) and Poecilia reticulata Peters , this last an exotic species.

Figures

Fig. 1. Ituglanis agreste, new species, holotype, MNRJ 40196, 40.5 mm SL, Brazil, Bahia State, municipality of Boa Nova, rio de Contas basin. a - lateral; b - dorsal; c - ventral views.

Fig. 4. Right suspensorium and opercular series of Ituglanis agreste,UFRN38, 41.8mmSL.Lateral view.The arrowindicates the interopercle plate broad and elongate.Abbreviations:HYO, hyomandibula; IOP, interopercle; MPT, metapterygoid; OPE, opercle; POP, preopercle; QUA, quadrate.Scale bar = 1 mm.

Fig. 2. Neurocranium and Weberian capsule of Ituglanis agreste, UFRN 38, 41.8 mm SL; a, dorsal view; b, ventral view. Abbreviations:AOR, antorbital;APA, autopalatine; BAO+EXO, basioccipital-exoccipital bone; EPO, epioccipital; FRO, frontal; FSO, parieto-supraoccipital fontanel; i1-i11, infraorbital pores; ll1-ll3, lateral line pores; LET, lateral ethmoid; MAX, maxilla; MET, mesethmoid; ORB, orbitosphenoid; PAS, parasphenoid; PMX, premaxilla; po1, preopercular pore; PSO, parietosupraoccipital; PSC, posttemporo-supracleithrum; PTE, pterotic; s1-s6, supraorbital pores; SPH+POT+PSF, sphenotic-prooticpterosphenoid; SSO, sesamoid supraorbital; VOM, vomer; WEB, Capsule of Weberian apparatus. Scale bar = 1 mm.

Fig. 3. Left mandible of Ituglanis agreste, paratype, UFRN 38, 41.8 mm SL. Medial view. Abbreviations:AAR, anguloarticulo-retroarticular; CPR, coronoid process; DEN, dentary. Scale bar = 1 mm.

Fig. 5. Left hyoid arch of Ituglanisagreste, paratype, UFRN38, 41.8mmSL.Ventralview.Abbreviations:ACH,anteriorceratohyal; BRR, branchiostegal rays; PCH, posterior ceratohyal; PUH, parurohyal; VHH, ventral hypohyal.Scale bar = 1 mm.

Fig. 6. Branchial skeleton of Ituglanis agreste, paratype, UFRN 38, 41.8 mm SL. Dorsal view (left dorsal elements and gill rakers not shown).Abbreviations: BB2-4, basibranchials 2 to 4; CB1-5, ceratobranchials 1 to 5; EB1-4, epibranchials 1 to 4; HB1-3, hypobranchials 1 to 3; PB3-4, pharyngobranchials 3 to 4; TPL, tooth plate. Scale bar = 1 mm.

Fig. 7. Left Pectoral girdle of Ituglanis agreste, paratype, UFRN 38, 41.8 mm SL. Ventral view. Abbreviations: CLE, cleithrum; PTR, pectoral rays; PR1, proximal radial 1 (cartilaginous); PR2, proximal radial 2; SCO, scapulocoracoid. Scale bar = 1 mm.

Fig. 8. Pelvic girdle of Ituglanis agreste, paratype, UFRN 38, 41.8mmSL.Dorsalview.Abbreviations:APS,anteriorprocesses; AMP, anterior medium processes; BPT, basipterygium; PSP, pelvic splint; PVR, pelvic rays. Scale bar = 1 mm.

Fig. 9. Caudal skeleton of Ituglanis agreste, paratype, UFRN 38, 41.8 mm SL. Left lateral view. Abbreviations: HS, hemal spines; H3, hypural 3; H4+H5, hypurals 4 and 5 fused; NS, neural spine; PC1+UR, pleural 1 and ural fused; PC2, pleural centrum 2; PH+HU1+HU2, parhypural partially fused to hypurals 1-2; UN, uroneural. Scale bar = 1 mm.

Fig. 10. Geographic distribution of the three Ituglanis species in northeastern Brazil. The locality of Ituglanis agreste (rio Tarugo) represents the type locality.