Ituglanis cahyensis, Sarmento-Soares & Martins-Pinheiro & Aranda & Chamon, 2006

Sarmento-Soares, Luisa M., Martins-Pinheiro, Ronaldo F., Aranda, Arion T. & Chamon, Carine C., 2006, Ituglanis cahyensis, a new catfish from Bahia, Brazil (Siluriformes: Trichomycteridae), Neotropical Ichthyology 4 (3), pp. 309-318 : 310-316

Ituglanis cahyensis , new species

Fig. 1

Holotype. MNRJ 28404 (48.6 mm SL), Brazil, Bahia: Prado, rio Palmares on road Guarany- Corumbau , in direction to Corumbau after the joint with the road to the mouth of rio Cahy , (16º57’48"S 39º16’33"W), 24 Oct 2004, L. M. Sarmento-Soares, A. T. Aranda, C. C. Chamon & R. F. M. Pinheiro.

Paratypes. Brazil, Bahia: MNRJ 28405 (2 C&S, 41.3-48.6 mm SL) collected with the holotype . MNRJ 28406 (1, 28.6 mm SL), Prado, rio Palmares on road Guarany-Corumbau , near Palmares (16º56’25"S 39º19’48"W), 24 Oct 2004, same collectors as holotype .

Diagnosis. The new species is distinguished from most of its congeners, except I. macunaima and I. parahybae , by the pectoral fin ray count of i,4. The coloration pattern with longitudinal rows of coalescing blotches differentiate the new species from all its congeners, with the exception of I. parahybae , from whom it is distinguished by the supraorbital laterosensory canal branch with pores s3 and s6 present (vs. pores s3 and s6 absent in I. parahybae ).

Ituglanis cahyensis is distinguished from I. amazonicus by the higher number of ribs, four (vs. three), by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern blotched (vs. uniformly colored, with grayish dots). From the subterranean species I. bambui , I. epikarsticus , I. passensis and I. ramiroi by the color pattern with round dark spots often coalescent and forming longitudinal rows (vs. pale yellowish with no rows of dark pigmentation) and by the normally developed eyes, with orbital diameter corresponding to more than 7.0% of HL (vs. less than 6.1% of HL). From I. eichorniarum by the low number of branched dorsal fin rays, seven (vs. eight), by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern with rows of dark blotches (vs. scattered small spots). From I. gracilior by the higher number of ribs, four (vs. two or three), by the low vertebral count, 40 (vs. 41-43), by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern with longitudinal rows of coalescing blotches (vs. scattered spots). From I. guayaberensis by the color pattern with longitudinal rows of coalescing blotches (vs. scattered dark brown spots). From I. herberti by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern with longitudinal rows of coalescing blotches (vs. faint light brown spots). From I. laticeps by the pectoral fin ray counts i,4 (vs. i,6), by the branched caudal fin rays 5/5 or 5/6 (vs. 6/7), by the high vertebral count, 40 (vs. 37) and by the color pattern with longitudinal rows of coalescing blotches on trunk (vs. obscure spots). From I. macunaima by the presence of a posterior cranial fontanel (vs. absence), by the higher number of pleural ribs, four (vs. two or three) and by the higher number of vertebrae, 40 (vs. 35-38). From I. metae by the pectoral fin rays i,4 (vs. i,5), by the low number of pelvic-fin rays i,3 (vs. i,4), by the branched caudal-fin rays 5/5 or 5/6 (vs. 6/6 or 6/7) and by the color pattern with longitudinal rows of coalescing blotches on trunk (vs. dark brown spots). From I. nebulosus by the pectoral-fin rays i,4 (vs. i,5), by the branched caudal fin rays 5/5 or 5/6 (vs. 6/6), by the number of ribs, four (vs. five), by the higher vertebral count, 40 (vs. 35-36), by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern with longitudinal rows of coalescing blotches on trunk (vs. dark blotches not forming rows). From I. parkoi by the low number of pelvic-fin rays i,3 (vs. i,4), by the supraorbital laterosensory canal lacking pore s1 (vs. s1 pore present), and by the color pattern with longitudinal rows of coalescing blotches on trunk (vs. obscure spots not forming rows). Ituglanis cahyensis is distinguished from its geographically closest congeners, I. parahybae and I. proops , by the lower number of ribs, four (vs. six in both species), by differences on the extension and pores of supraorbital laterosensory canal (see below), and by some proportional measurements.

Ituglanis cahyensis share with I. proops a high number of vertebrae (40), and the supraorbital laterosensory canal with pores s3 and s6. The morphological similarity regarding supraorbital laterosensory canal is only superficial, as the number of pores in I. cahyensis is smaller compared to I. proops , as pores s1 and s2 are missing in the new species (vs. present in I. proops ). Ituglanis cahyensis and I. proops have different pectoral- and pelvic-fin ray counts. Four branched pectoral fin rays in the new species (vs. six in I. proops ) and three branched pelvic fin rays (vs. four in I. proops ). Ituglanis proops is a species with an adult size proportionally large, between 60-68.9 mm SL, in comparison to I. cahyensis , which attains adult size with about 40-48.6 mm SL. Ituglanis cahyensis has a proportionally elongated body, with a long preanal length, 70.3-73.3% in SL, and a long prepelvic length, 59.3-62.6% in SL (vs. proportionally short body in I. proops , with preanal length 64.7-69.8% in SL and prepelvic length 52.2-58.1% in SL). The new species is also distinct regarding the elongate barbels. The nasal, maxillary, and rictal barbels are longer than those of I. proops (see Table 2). Ituglanis cahyensis has short head measurements in comparison to I. proops , such as a short head width, 76.0-79.8% in HL (vs. 82.4-87.9% HL in I. proops ); a small eye diameter, 7.0-8.1% in HL (vs. 9.3-13.5% HL in I. proops ) and a small mouth width, 30.7-33.8% in HL (vs. 38.2-42.6% HL in I. proops ). The color pattern is also distinctive between the two species. The new species has spots often coalescent, forming longitudinal rows, while I. proops has scattered spots along the sides of body, not forming rows.

Ituglanis cahyensis is morphologically similar to I. parahybae , in several aspects. Both species share a low pectoral- and pelvic-fin ray counts: four branched pectoral-fin rays and three branched pelvic-fin rays respectively, and also a similar color pattern (see discussion). Regarding meristic features the new species has seven branchiostegal rays (vs. eight in I. parahybae ), four paired ribs (vs. six in I. parahybae ) and 40 vertebrae (vs. 38-39 in I. parahybae ). In spite of the ob- served differences on meristic features, the ranges are very close between the two species. The two species are evidently distinct regarding the cephalic laterosensory system, as the supraorbital canal in I. cahyensis is extended along frontal bone, opening into pores s3 and s6, while in I. parahybae the entire supraorbital laterosensory canal is lacking (Costa & Bockmann, 1993: fig. 3 a; Datovo & Landim, 2005: 463; present paper). Ituglanis cahyensis is further distinguished from I. parahybae by the taller head depth, 41.3-44.6% in HL (vs. 27.3-38.1% HL in I. parahybae ) and by the small eye diameter, 7.0-8.1% in HL (vs. 9.1- 11.5% HL in I. parahybae ).

Description. Morphometric and meristic data presented in Table 2. Body slim, trunk compressed, caudal peduncle laterally flattened. Dorsal profile of body ascent from tip of snout to anterior portion of trunk, approximately straight from that point to base of dorsal fin, descending along dorsal-fin base and straight on caudal peduncle until caudal fin. Ventral profile of head gently sloped. Ventral profile of body almost straight to somewhat convex.

Head small and slightly depressed. Eyes small, orbital margin not free. Skin covering eye thick, difficulting identification of eye in alcohol preserved specimens. Anterior nostril small surrounded by fleshy tube-shaped flap of integument. Posterior nostril larger surrounded anteriorly by raised fleshy flap and located slightly closer to anterior nostrils than to eye. Mouth inferior, lower lip contoured by conspicuous fleshy lobe medial to origin of rictal barbels. Upper lip with fleshy rictal fold. Nasal barbel originating on lateral portion of integumentary flap around anterior nostril; tip of barbel reaching opercular odontode patch. Maxillary and rictal barbels extend to pectoral-fin origin. Autopalatine with mesial margin notched, posteriorly expanded with wide lateral projection; maxilla well developed and curved. Premaxilla narrow, transversely elongated, meeting its counterpart medially. Jaws sub-equal; premaxilla and dentary almost straight with two well defined regular rows of short conical teeth. Branchiostegal membranes thick, united to isthmus only anteriorly.

Mesethmoid long, thin, with anterior border slightly convex, premaxillaries held underneath narrow anterior cornua through synchondral articulation. Lateral ethmoid projected laterally.Anterior cranial fontanel elliptical bounded by frontals ( Fig. 2a ). In smaller C&S specimen narrow opening between frontals anteriorly to fontanel present, but closed in largest specimen. Minute supraoccipital fontanel represented by single posterior opening present.Antorbital very short slightly curved towards its distal portion. Fronto-lacrimal tendon-bone very long, rod-like, with short, sharp, lateral projection. Anterior portion of sphenotic-prootic-pterosphenoid projected anteriorly in dorsal view, giving off infraorbital sensory canal openings. Pterotic laterally projected. Posttemporo-supracleithrum small, giving off supraorbital laterosensory branch. Vomer arrow-shaped, narrow, with long lateral and posterior processes. Parasphenoid with long and pointed posterior process, reach- ing middle of basioccipital-exoccipital. Anterior portion of Weberian complex fused to basioccipital-exoccipital.

Suspensorium with robust hyomandibula, projected anteriorly as membranous outgrowth. Laminar projection of hyomandibula anteriorly sutured to quadrate only, with no contact with metapterygoid. Metapterygoid short, laminar, almost rectangular joined to quadrate via anterior cartilage block only. Quadrate elongate, with broad base and anterior laminar projection through which this bone contacts to both hyomandibula and metapterygoid. Quadrate and hyomandibula contacted also through their broad bases and cartilaginous joint. Short preopercle sutured to ventral margins of both quadrate and hyomandibula. Opercular patch of odontodes small and roundish. Opercle with 9-12 elongate odontodes, posterior ones longest. Interopercular patch of odontodes narrow and reduced, with short anterior process. Interopercle with 16 odontodes arranged into two rows, 7-9 large odontodes in medial row and 7-9 smaller odontodes on lateral row ( Fig. 3).

Urohyal well-developed with both long dorsal process and laminar surface, bearing conspicuous foramen. Hyoid arch with large ventral hypohyal, elongate anterior ceratohyal and somewhat triangular posterior ceratohyal, with markedly concave posterior face and with articulatory surface for interopercle. Posterior ceratohyal with small foramen in smaller c&s specimen. Seven branchiostegal rays articulated with hyoid arch: three with anterior ceratohyal, two with interceratohyal cartilage between bones, and two with posterior ceratohyal. Brachiostegal rays 4 to 6 distally expanded and notched ( Fig. 4 ). Dorsal hypohyal and interhyal absent.

Basibranchial 1 absent; basibranchial 2 and 3 with cartilaginous anterior and posterior tips, connected to each other forming osseous rod.Anterior cartilaginous tip of basibranchial axis reaches close to hipobranchial 1; posterior osseous tips nearly in contact with contralateral hypobranchial 3. Cartilage between basibranchial 2 and 3 is bordered laterally by cartilaginous head of hypobranchial 2. Basibranchial 4 hexagonal and completely cartilaginous bordered anteriorly by cartilaginous head of ceratobranchial 4 and posteriorly by cartilaginous head of ceratobranchial 5. Hypobranchial 1 osseous, rod like, with cartilage on its proximal and distal tips. Hipobranchial 2 elongate, cartilaginous, almost trapezoid, with an osseous anterodistal process. Hypobranchial 3 approximately trapezoidal, mostly cartilaginous and closely positioned relative to its counterpart. Hypobranchial 4 absent. Five ceratobranchials present mostly ossified, with cartilage on their extremities. First ceratobranchials short, supporting one or two diminute rakers. Second and third ceratobranchials with shallow cavity in their posterior margins and mesial laminar extension. Fourth ceratobranchial almost straight. Fifth ceratobranchial with short proximal tip and anterior concavity, and slightly expanded posteromedially to support lower pharyngeal toothplate dorsally, with fine conical teeth arranged in 2 rows, with about 5 teeth in mesial row. Five epibranchials, first three-rod like, short and delicate, ossified; except for its cartilaginous extremities. Posterior margin of epibranchial 1 with small process. Epibranchial 2 with processes on its anterior and posterior margins. Epibranchial 3 with elongate posterior uncinate process. Epibranchial 4 broad, somewhat rectangular. Epibranchial 5 very small, completely cartilaginous, placed between posterior cartilaginous tips of epibranchial 4 and ceratobranchial 4. Pharyngobranchials 1 and 2 absent. Pharyngobranchial 3 elongate, ossified rod-like, with cartilaginous tips. Pharyngobranchial 4 ossified, giving support to upper pharyngeal tooth plate, with long conical teeth arranged in two rows; eight teeth on the main row ( Fig. 5 ).

Cephalic sensory canals enclosed in bones, with some branches deeply embedded in those bones. Head sensory canals with simple tubes ending in single pores. All canals continuous and connected to each other. Supraorbital sensory canal running along frontal bone, deeply embedded in it. Supraorbital canal gives off two pores: pore s3 placed on anterior margin of frontal, and pore s6 on interorbital region. Supraorbital canal joining infraorbital canal in anterior part of sphenotic. Infraorbital canal incomplete, running along surface of head, reduced to its posterior segment. Infraorbital sensory canal gives off two pores, pores i10 and i11, present ventroposteriorly to eyeball. Temporal sensory canal extends from posterior limit of optic sensory canal to anterior limit of lateral line. Postotic canal with pores p1 and p2 (fig. 2). Preoperculo-mandibular sensory canal absent. Otic sensory canal short, without pores. Lateral line canal very short, with two pores, extending from posteriormost region of opercle to about level of anterior vertebrae.

Dorsal-fin margin somewhat rounded, with 2 unbranched plus 7 branched rays. Basal dorsal-fin radials 7. Origin of dorsal fin on vertical of about 23 rd or 24 th vertebra. Pectoral fin with one unbranched plus 4 branched rays. Tip of first unbranched pectoral fin ray prolonged in filamentous portion. Pelvic fin very small, with one unbranched plus 3 branched rays and margin rounded. Pelvic fin originated on vertical of about 20 th vertebra. Anal fin with two procurrent rays; two unbranched rays plus 5-6 branched rays. Anal fin pterygiophores arranged in 6-8 elongate thin proximal radials and 5-6 very small completely cartilaginous distal radials. Caudal fin semi-truncated, 5/5 or 5/6 principal rays; dorsal lobe procurrent 12; ventral lobe procurrent 12. Precaudal vertebrae 12. Total vertebral count 40. Paired pleural ribs 4, becoming progressively small anteroposteriolly. First pleural rib slightly thick in comparison to subsequent ones; last fifth unpaired rib being present only on right side of body in both C&S examined specimens.

Color in alcohol. Overall coloration remains visible, but ground color in ethanol becomes pale brown, with dark brown blotches and spots. Dorsal surface of head with groups of dark brown chromatophores, more concentrated on nape. Trunk with five rows of dark brown blotches: an unpaired middle row runs along dorsal portion of trunk, followed by two paired rows along latero-dorsal sides of body. Latero-ventral parts of body becoming gradually less scattered towards ventral parts. Nasal and maxillary barbels with chromatophores on their dorsal surface. Rictal barbel less pigmented on its proximal tip. Unpaired fins with light brown pigmentation concentrated on fin membrane. Pectoral fin with dark brown pigmentation limited to its basal part. Pelvic fins hyaline.

Live coloration. Ground color pale yellow, mottled with grayish brown blotches, coalescing irregularly, and spots, forming longitudinal rows on trunk. Two longitudinal rows of coalescing blotches on lateral sides of trunk, and one mid-dorsal row. Mid-dorsal row distinguished only on anterior portion of body, as blotches become progressively continue with lateral row close to dorsal-fin insertion. Head pale yellow to orange-yellow with scattered grayish brown chromatophores. Ventral surface of head and belly white. Fins almost hyaline. ( Fig. 6 ).

Distribution. Known only from rio Palmares a tributary of the rio Cahy, a small coastal river drainage from southeastern Bahia State in Brazil ( Fig. 7 ).

Etymology. The specific name cahyensis is in reference to the rio Cahy, the main river of the basin where the new species was captured. The mouth of the rio Cahy is a place of great historical significance, as it is located near the point where the Portuguese navigator Pedro Alvarez Cabral and its fleet landed in Brazil for the first time in the year 1500.

Ecological notes. The rio Palmares is the northernmost tributary of the rio Cahy drainage, with shallow waters, with approximately 1.5 m of depth where the catfish samples were collected ( Fig. 8 ). The small Ituglanis catfishes were sampled in brown waters, with moderate flowing current and a sandy or gravel bottom. The environment around the river was deforested, with few floating meadows and moderately vegetated on its margins.

The stomach contents of two specimens were analyzed (MNRJ 28405, female, with unknown size due to a damaged caudal peduncle and MNRJ 28405, male, 41.3 mm SL). The stomachs were partially empty, but with remaining fragments of insect larvae, nymphs, and organic matter in advanced state of digestion. The macroscopic examination of gonads of both specimens revealed that the female was in maturing stage, while the male was in depletion stage, an indicative that the small catfishes were reproducing by the time of their capture.

Figures

Fig. 1. Ituglanis cahyensis, holotype, MNRJ 28404, 48.6 mm SL. Rio Palmares on the road Guarany-Corumbau, Prado, Bahia, Brazil. a. lateral; b. dorsal; c. ventral views.

Fig. 2. Neurocranium and Weberian apparatus of: a. Ituglanis cahyensis, MNRJ 28405, paratype, 41.3 mm SL. b. Ituglanis parahybae, MNRJ 15413, 35.4 mm SL. c. Ituglanis proops MNRJ 13597, 60.5 mm SL. Dorsal view.Abbreviations:ao, antorbital; ap, autopalatine; ep, epioccipital; fr, frontal; ffr, frontal fontanel; fl, fronto-lacrimal tendon bone; fllp, fronto-lacrimal lateral process; fso, parieto-supraoccipital fontanel; i10, i11, infraorbital sensory pores 10 to 11; le, lateral ethmoid; me, mesethmoid; mx, maxilla; pm, premaxilla; ps, posttemporosupracleitrum; pt, pterotic; p1, p2, postotic sensory pores 1 to 2; so, parieto-supraoccipital; sp, sphenotic; s1, s2, s3, s6, supraorbital sensory pores 1 to 6; wcc, weberian complex and capsule. Scale bar = 1.0 mm.

Fig. 4. Left hyoid arch of Ituglanis cahyensis, MNRJ 28405, paratype, 41.3 mm SL. Ventral view.Abbreviations: ac, anterior ceratohyal; br, branchiostegal rays; ic, interceratohyal cartilage; pc, posterior ceratohyal; vh, ventral hypohyal; udp, urohyal dorsal process; uls, urohyal laminar surface; ur, urohyal. Scale bar = 1.0 mm.

Fig. 5. Branchial skeleton of Ituglanis cahyensis, MNRJ 28405, paratype, 41.3 mm SL. Dorsal view (right dorsal elementsand gill rakers not shown).Abbreviations: bb2 to bb4, basibranchial 2 to 4; cb1 to cb5, ceratobranchials 1 to 5; dp, dentigerous plate; eb1 to eb5, epibranchials 1 to 5; hb1 to hb3, hypobranchials 1 to 3; pb3 to pb4, pharyngobranchials 3 and 4. Scale bar = 1.0 mm.

Fig. 6. Ituglanis cahyensis, new species. Specimen photographed alive in a field aquarium shortly after collection.

Fig. 7. Drainages of eastern Brazil between rio São Francisco and rio Paraíba do Sul, illustrating the distribution of the Ituglanis species in the area. Symbols may represent more than one locality. In detail, collecting localities of Ituglanis cahyensis in the study area, between the rio Mucuri and rio Jequitinhonha.

Fig. 8. Rio Palmares, a small stream, Prado, Bahia, northeastern Brazil, type locality of Ituglanis cahyensis.