Hisonotus carreiro, Carvalho & Reis, 2011

Carvalho, Tiago Pinto & Reis, Roberto E., 2011, Taxonomic review of Hisonotus Eigenmann & Eigenmann (Siluriformes: Loricariidae: Hypoptopomatinae) from the laguna dos Patos system, southern Brazil, Neotropical Ichthyology 9 (1), pp. 1-48 : 27-30

Hisonotus carreiro , new species

Figs. 4d, 8d, 28, and 29

Hisonotus sp. 2 . -Reis & Carvalho, 2007: 84 [listed].

Holotype. MCP 44515, 35.4 mm SL, female, Brazil, Rio Grande do Sul, Serafina Corrêa, rio Carreiro downstream Carreiro bathing spot, 28º42’10”S 51º50’57”W, 25 Oct 2006, T. P. Carvalho & V. A. Bertaco.

Paratypes. All from Brazil, Rio Grande do Sul, rio Carreiro drainage. ANSP 188702 , 3 , 27.7-28.3 mm SL; MCP 40495, 2 + 2 c&s, 27.5-31.2 mm SL; MZUSP 104944 , 3 , 27.8-28.6 mm SL; collected with the holotype. MCP 41548, 1 , 32.0 mm SL, collected at type locality, 11 Jan 2006, J. P. Silva & T . P. Carvalho. MCP 40943, 3 , 33.6-35.8 mm SL, Guabiju, arroio Guabiju on secondary road between Guabiju and Vila São Jorge , 28º30’49”S 51º41’22”W, 24 Oct 2006, T . P. Carvalho & V . A. Bertaco. MCN 16361, 3, 34.4-35.4 mm SL , Nova Araçá, arroio Guabiju on road between Guabiju and Vila São Jorge , 28º30’S 51º41’W, Out 2000, W. Koch. UFRGS 6961 , 7 , 31.7-37.8 mm SL, Serafina Corrêa, rio Carreiro , 28º44’S 51º50’W, Nov 2004, J. Anza .

Diagnosis. Hisonotus carreiro differs from its congeners, except H. francirochai , H. iota , H. leucophrys , and H. prata by the presence of a conspicuous tuft of enlarged odontodes on the tip of the parieto-supraoccipital, vs. odontodes on the tip of parieto-supraoccipital similar in size, not enlarged, or only slightly enlarged. It differs from H. francirochai , H. leucophrys , and H. iota by having the anterior portion of snout with a narrow odontode-free band ( Fig. 29), vs. snout completely covered with odontodes, without an anterior band free of odontodes. Hisonotus carreiro can be distinguished from H. prata by having a longer dorsal-fin spine 24.3- 29.0% SL, mean 26.6%, vs. 22.6-25.5% SL, mean 24.5% ( Fig. 30); longer pectoral-fin spine 24.7-29.0% SL, mean 26.7 %, vs. 22.0-25.6% SL, mean 24.0% ( Fig. 31); and by its general color pattern of the body, which is yellowish in life and pale yellow to light brown in alcohol preserved specimens, vs. a dark green general color pattern of the body in life and a dark gray to dark brown color in alcohol preserved specimens.

Description. Morphometrics and meristics in Table 8. Adult size small to medium for members of this genus (maximum size 37.8 mm SL). Body relatively stocky, not elongated, without conspicuous keels. Caudal peduncle round in cross section. Dorsal profile slightly concave from tip of snout to nares, convex from nares to tip of parieto-supraoccipital, almost straight and posterodorsally inclined from that point to dorsalfin origin. Dorsal-fin base straight and posteroventrally sloped, almost straight to slightly concave from posterior end of dorsalfin base to caudal-fin origin. Greatest body depth at dorsal-fin origin. Least body depth at middle of caudal peduncle. Posterior profile of caudal fin concave. Head and snout broad, snout rounded in dorsal view, body progressively narrowing posterior to pectoral-fin insertion. Snout region anterior of nares concave, interorbital region convex. Upper margin of orbit somewhat elevated. Eye dorsolaterally positioned. Iris operculum present.

Pectoral fin I,6. Pectoral-fin posterior margin almost straight; when depressed tip extending beyond middle of pelvic fin. Posterior margin of pectoral-fin spine smooth in adults, juveniles with feeble serrae at distal portion. Pectoralfin axillary slit present, located below posterior bony margin of cleithral process. Pelvic fin i,5. Tip of depressed fin not reaching anal-fin origin in females, but extending beyond that point in males. Dorsal fin II,7. Dorsal-fin origin located just posterior of vertical through pelvic-fin origin. Dorsal-fin spinelet present, laterally extended, one c&s specimen lacking spinelet.Anal fin with i,5. First anal-fin pterygiophore exposed anterior to anal fin. Adipose fin absent. Caudal fin i,14,i.

Body almost entirely covered by plates except for region overlying opening of swim bladder capsule, area between pectoral girdle and lower lip, region around anus, and area around base of paired fins. Rostral plate with posterior notch articulation with mesethmoid. Rostral plate thickened, with narrow odontode-free band between dorsad and ventrad series of odontodes ( Fig. 29), sometimes absent at medial portion of some specimens. Snout plates anterior to nares reduced, small unplated area between rostrum and nostril at lateral portion.

Two or three rows of predorsal plates (rarely two). Lateral line incomplete, with small gap without pores along middle length of body. Median plate series truncated ( Fig. 4d). Abdominal plates arranged in three rows anteriorly and irregularly arranged between pelvic-fin insertions. Lateral abdominal plates slightly larger and forming regular series. Median abdominal series.

usually formed by one plate row. Area between lateral and median abdominal plate series naked in some specimens ( Fig.

8d). Coracoid and cleithrum exposed and covered by odontodes, except for median region of cleithrum between arrector fossae openings and medial region of coracoids.

Odontodes on parieto-supraoccipital tip greatly enlarged,

arranged in round patch. Odontodes approximately five times larger than those of surrounding areas. Head, fin-spines, and body plates covered with odontodes, larger on anterior surface of all fin spines, and on ventral and dorsal margin of rostrum medially. Odontodes medially directed in pelvic-fin thickened unbranched ray. Anteroventral margin of compound pterotic with median-to-large size perforations.Infraorbitalseriesentering infraorbital canal via sphenotic. Lips roundish and papillose, posterior border of lower lip fimbriate. Maxillary barbel present.

Premaxillary and dentary teeth slender proximally and flattened distally; bifid, major (medial) cusp large and rounded, minor (lateral) minute pointed. Accessory patch of teeth absent on dentary and premaxilla.

Compound ventral hypural plate (hypurals 1-2) and compound dorsal hypural plate (hypurals 3-5) completely fused to each other, a median notch on the posterior margin of caudal-fin skeleton. Total vertebrae 28 (2 c&s).

Color in alcohol. Ground color of dorsal and lateral surfaces pale yellow to light brown. Dorsal and lateral body surfaces with scattered dark brown round spots. Dorsal and lateral portions of head darker than body. Ventral and ventrolateral surface of body yellowish except for scattered chromatophores, these grouped forming spots on ventral surface of caudal peduncle. Region anterior to nares lighter than surrounding areas, but not forming conspicuous longitudinal light stripes posterior to that point. Paired, anal, and dorsal fins mostly brown, sometimes with light transverse bands, forming striped pattern. Caudal fin almost completely brown, except for one pair of somewhat round hyaline areas in middle portion of upper and lower lobes. Unbranched rays of caudal fin with alternating transverse light bands and dark areas.

Sexual dimorphism. Urogenital papilla positioned just behind the anal opening in males. Adult males also possess a developed fleshy flap along the dorsal margin of first thickened pelvic-fin ray that is absent in females. Flap slightly wider basally and progressively narrowing distally. In males, first and second branched rays of pelvic fin with a fleshy flap in medial portion. In juvenile males, flaps are smaller or absent. Males have a longer pelvic-fin thickened unbranched ray that extends far beyond the anal-fin origin, with the pelvic-fin ray reaching just to the origin of anal fin in females.

Distribution and habitat. Hisonotus carreiro is endemic to rio Carreiro drainage, a tributary to the rio Taquari, which flows into the rio Jacuí basin in the laguna dos Patos system ( Fig. 32). This species inhabits relative high altitudes, above 400 m. The habitat in rio Carreiro is a rapid flow watercourse, a wide river with about 0.5 m deep, with clear water and rocky bottom ( Fig. 10a). The specimens were caught between aquatic vegetation of Echinodorus , which form green islands on the faults of the rocky substrate. The arroio Guabiju is a small stream about 3 m wide and up to 1 m deep, with clear water, running over a sandy and rocky bottom.There, the species is caught in marginal submersed vegetation. Hisonotus carreiro is sympatric with the undescribed Hypoptopomatinae Eurycheilichthys sp. 1 in arroio Guabiju. Its type locality is now flooded by the reservoir of the Caçador Hidroelectric Dam. The changes in the environment from a rapid running river to a lentic habitat is likely to promote the disappearance of this species in that region.

Etymology. The specific epithet, carreiro , refers to rio Carreiro, the river basin where this species is known. It is treated as a noun in apposition.