Lamontichthys avacanoeiro, Paixão & Toledo-Piza, 2009

Paixão, Andrea de Carvalho & Toledo-Piza, Mônica, 2009, Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species, Neotropical Ichthyology 7 (4), pp. 519-568 : 525-527

Lamontichthys avacanoeiro , new species Fig. 8

Holotype. MNRJ 32795, 150.5 mm SL, Brazil, Goiás, rio Tocantins, pools below U.H.E. Serra da Mesa , 1996, D. F. Moraes et al.

Paratypes. (22 specimens; 47.6-159.9 mm SL). Brazil. Goiás : MNRJ 18553 , 1 cs, 7 alc, 76.0-145.6, same data of holotype ; MZUSP 54090 , 2 , 47.6 - 58.4 , rio Tocantinzinho and tributaries, Serra da Mesa, 48°21’66”S 13°53’33”W, 28 Out 1996, Expedition MZUSP / MNRJ; MZUSP 61974 , 5 , 1 cs*, 113.7-159.9, upper rio Tocantins , Minaçu, Serra da Mesa , 26 Out 1996, A. Akama & O . T. Oyakawa ; MZUSP 79750 , 5 , 90.9 - 96.8 , upper rio Tocantins , Uruaçu, rio Passa Três , above Ponte Nova, on road BR 153 , 10 Jun 1998, D. F. Moraes .

Non-types. (4 specimens; 83.4-106.8 mm SL): Brazil: Goiás : MNRJ 23641 , 1 , 100.3 , upper rio Tocantins , rio das Almas; MNRJ 23642 , 1 , 106.8 , upper rio Tocantins , rio Bagagem , above ferry-boat to Garimpinho ; MNRJ 23643 , 2 , 83.4 - 83.7 , upper rio Tocantins , Niquelândia, rio Traíras , above Indianópolis .

Diagnosis. Lamontichthys avacanoeiro differs from all congeners in the shorter first branched dorsal-fin ray (22.6- 26.0%, vs. 26.4-40.5% SL) in specimens larger than 70 mm SL.

Lamontichthys avacanoeiro can be further distinguished from L. filamentosus , L. llanero , and L. maracaibero by the anterior tip of the snout with an oval shaped area without plates (vs. tip of snout totally covered with plates or, with only a very small area lacking plates), and by the teeth with long cusps (vs. short) ( Fig. 3). Lamontichthys avacanoeiro can be further distinguished from L. filamentosus and L. llanero by the lower lip semi-oval shaped (vs. semicircular) ( Fig. 9). Lamontichthys avacanoeiro also differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior margin of the anus (vs. one plate) ( Figs. 1 and 5) and in the greater abdominal length in specimens larger than 150 mm SL (17.6-17.7% [n = 2], vs. 14.1-16.3% SL [n = 5]). Lamontichthys avacanoeiro can be distinguished from L. parakana by the more posterior location of the anal-fin origin (at the vertical through the distal tip of the last dorsal-fin ray, vs. anterior to that point), by the shorter unbranched anal-fin ray (16.9-20.3%, vs. 21.4-24.8% SL), and by the smaller orbital diameter (13.6-16.2%, vs. 16.6- 17.3% HL) in specimens larger than 70 mm SL.

Lamontichthys avacanoeiro also differs from specimens of L. parakana larger than 100 mm SL in the narrower head (91.3-100.9%, vs. 101.3-106.1% HL).

Description. Morphometric and meristic data presented in Table 1. Largest specimen 159.9 mm SL. Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly to caudal-fin base and, anteriorly, to snout tip. Head ellipse shaped in dorsal view. Dorsal profile of head slightly convex. Dorsal profile of body straight from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of longest anal fin ray, straight from that point to caudal-fin base. Largest body width at cleithrum, gradually narrower posteriorly to 20 th to 21 st lateral plate of median series, more abruptly posteriorly into caudal-fin base. Caudal peduncle long, narrow and very depressed. Ventral profile of body and head straight from snout tip to base of caudal fin. Pectoral-fin origin at vertical through posterior margin of orbit. Dorsal-fin origin immediately anterior to vertical through pelvic-fin origin.Analfin origin at or slightly posterior to vertical through distal tip of last dorsal-fin ray.

Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral, upper and lower lips semi-oval shaped. Lower lip extending short of vertical through anterior margin of orbit and covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower than lower lip, its ventral surface (internal) with small papillae and dorsal surface (external) with small, round plates covered with odontods. Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip.

Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader unbranched lower caudal-fin ray. Fins and dorsal region of body and head with dark brown and yellow spots. One dark brown, longitudinal band extending from base of dorsal fin to base of caudal fin. than lateral cusp. Number of jaw teeth increasing with growth. Number of premaxillary teeth approximately 8% greater than number of dentary teeth. Emergent teeth placed in two irregularly arranged rows; teeth gradually smaller laterally. Replacement teeth oriented at 90 degrees relative to emergent teeth and covered with skin. Anteroventral tip of snout without plates, forming distinct naked portion, approximately oval shaped, covered with stiff connective tissue. Anterior border of head covered with small and flexible plates between snout tip and anterolateral margin of upper lip. Lateral border of head covered with large dorsal plates anteroventrally curved.

Three horizontal keels along trunk, on lateral plates, converging from plate 5 to 15 or 16, continuing as a single keel posteriorly. Lower keel more evident, upper keel less evident. Last lateral plate of median series small and triangular, with one diminutive plate on each side of its base, located between two other plates of similar shape (one upper and other lower), above caudal-fin base. Lateral plates of median series, 31 to 34. Lateroventral thoracic plates 6 to 9 in specimens larger than 50 mm SL. Ventral thoracic plates, small, lozenge shaped, irregularly arranged in oblique rows; longest row with 8 to 10 plates delimited by ventrolateral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge-shaped plates followed by three large polygonal plates, and the anal plate larger and bordering anterior margin of anus.

Pectoral- and dorsal-fin spines, unbranched pelvic- and anal-fin rays not projecting as long filaments. Unbranched caudal-fin rays projecting as long filaments. Branched caudalfin rays gradually longer toward dorsal and ventral unbranched rays. Dorsal most branched caudal-fin ray longer than ventral most ray. Unbranched pelvic-fin ray reaching to vertical through second ventral plate, located posterior to base of last anal-fin ray, unbranched anal-fin ray reaching to vertical through seventh ventral plate, located posterior to the base of last anal-fin ray. Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i.

Color in alcohol. Ground coloration of head and body of adults and juveniles varying between brown and yellow. Ventral region of head and body lighter, uniformly yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from base of last anal-fin ray to base of Etymology. The species name, avacanoeiro, is in reference to the Avá-canoeiros, inhabitants from the upper rio Tocantins basin. Avá-canoeiros, an American group that historically inhabited the area of the upper rio Tocantins, drainage from which the examined specimens of the species in this study originated.