Hisonotus vireo, 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 : 33-38

Hisonotus vireo , new species

Figs. 4f, 8f, 27a, 36, 37, and 38

Hisonotus sp. 4 . -Reis & Carvalho, 2007: 84 [listed]. Hisonotus sp. 1 . - Cramer et al., 2007: 54 [included in molecular phylogeny].

Holotype. MCP 44518, 38.2 mm SL, female, Brazil, Rio Grande do Sul, Caraá, rio dos Sinos, brigde 7 km north of Caraá, road to Fundo Quente , 29º47’S 50º19’W, 12 Jan 1995, L. R. Malabarba, P. A. Buckup, A. R. Cardoso & G. M. Guazelli.

Paratypes. All from Brazil, Rio Grande do Sul, rio Jacuí basin, rio dos Sinos drainage: MCP 17643, 6 , 11.3-39.2 mm SL; MZUSP 104946 , 4 , 30.5-39.3 mm SL; collected with the holotype. ANSP 188704 , 4 , 31.0- 34.3 mm SL; MCP 14619, 4 + 3 c&s, 28.3-42.0 mm SL; Caraá , rio do Sinos , about 5 km north of Caraá , 29º46’S 50º20’W, 17 Jan 1991, N. A. Menezes, R. E. Reis & E. H. L. Pereira. MCP 17620, 9 , 30.0- 40.3 mm SL, Caraá, rio dos Sinos, at praia João Fernandes, about 4 km of Caraá and 5 km of Vila Rodolfo Tetour, 29º45’53”S 50º25’41”W, 12 Jan 1995, L. R. Malabarba, P. A. Buckup, A. R. Cardoso & G. M. Guazelli .

Non-type material. All from Brazil, Rio Grande do Sul, laguna dos Patos system. Rio Jacuí drainage: MCP 25459 15, 16.3- 38.7 mm SL and MCP 25719, 15 + 3 c&s, 24.1-39.1 mm SL, Ibarama, lageado do Gringo about 2 km from hidroeletrical power plant Dona Francisca, 29º26’49”S 53º15’36”W . MCP 26568, 6 , 26.5-36.8 mm SL, Nova Palma, arroio Caemborá near Caemborá, 29º28’50”S 53º 17’50”W . Rio Taquari drainage: MCP 38766, 15 + 3 c&s, 16.9-38.2 mm SL, Lageado, arroio Saraquá, near Botanic Garden of Lageado , 29º27’42”S 52º00’14”W . UFRGS 8812 , 14 , 32.5-39.9 mm SL, Lageado, confluence of arroio Pinheirinho with rio Forqueta. 29º19’21”S 52º14’03”W . MCP 41550, 4 , 14.6 -20.0 mm SL, Cotiporã, rio Carreiro at bridge on road between Dois Lageados and Cotiporã, 29º59’43”S 51º45’16”W . Rio Caí drainage : MAPA 1750 , 1 , 40 , 6 mm SL, Nova Petrópolis, rio Cadeia , between Joaneta and Pinhal Alto. MAPA 1751 , 2 , 33.0-40.0 mm SL, Nova Petrópolis, affluent of rio Cadeia at Picada Café . MAPA 2625 , 1 , 40.4 mm SL, Nova Petrópolis, arroio Macaquinhos tributary of rio Cadeia. Rio dos Sinos drainage : MAPA 724 , 1 , 22.9 mm SL, Taquara, rio Rolante between Taquara and Rolante. MAPA 1868 , 3 , 32.9-41.2 mm SL, Santo Antônio da Patrulha, rio dos Sinos, bridge at Santo Antônio da Patrulha . MAPA 2422 , 2 , 17.3-23.4 mm SL, Taquara, rio da Ilha entre Padilha e rio da Ilha . MAPA 2627 , 4 , 29.7-41.2 mm SL, Santo Antônio da Patrulha, rio dos Sinos, bridge at Nossa Senhora de Monte Serrat. MCN 6455, 1, 38.7 mm SL, Três Coroas , arroio José Velho between Canastra Alta and Linha Café. MCN 6920, 1, 36.0 mm SL, Três Coroas , arroio Moreira at confluence of arroio Quilombo. MCN 6863, 1, 39,3 mm SL, Três Coroas , arroio Quilombo at Sander. Rio Gravataí drainage : MCP 23875, 3 , 29.7-35.2 mm SL, arroio Itajacu, Glorinha, 29º47’34”S 50º42’07”W . Hisonotus cf. vireo: All from Brazil, Rio Grande do Sul, laguna dos Patos system. Rio Jacuí drainage: MCP 26855, 3 , 36.0- 41.7 mm SL, Júlio de Castilhos, arroio Tipiáia, about 13 km north of Júlio de Castilhos on road to Cruz Alta, 29º06’14”S 53º34’24”W . MCP 41074, 4 , 39.0- 44.2 mm SL, arroio Tipiáia (or arroio Passo dos Buracos), on road from Júlio de Castilhos to Cruz Alta, 29º06’48”S 53º39’01”W .

Diagnosis. Hisonotus vireo differs from its congeners, except from H. aky , H. brunneus , H. carreiro , H. charrua , H. heterogaster , H. laevior , H. megaloplax , H. montanus , H. nigricauda , H. notopagos , H. prata , H. ringueleti , and H. taimensis by having the anterior margin of the snout with an odontode-free band ( Fig. 38); vs. anterior margin of the snout complete covered by odontodes. Differs from those above, except H. carreiro , H. prata , and H. ringueleti by the caudalfin pigmentation, when well defined, composed of a dark background with a pair of hyaline areas, in the middle portion of upper and lower lobes, vs. a dark background without hyaline areas or a transverse hyaline band at the middle of caudal-fin length. Hisonotus vireo differs from H. ringueleti by having the posterior margin of the pectoral-fin spine smooth in specimens between 25 and 35 mm SL, vs. posterior portion of spine serrate in specimens between 25 and 35 mm SL, and by having the abdomen completely covered by abdominal plates ( Fig. 8f), vs. abdomen having a large naked area medially on the anterior portion. Differs from H. carreiro and H. prata by the absence of a raised tuft of odontodes on the posterior parieto-supraoccipital tip on adults, juvenile specimens presenting slightly enlarged odontodes, vs. a conspicuous tuft of enlarged odontodes at posterior parietosupraoccipital tip, and median lateral plate series complete, not truncated ( Fig. 4f), vs. median lateral plate series truncated ( Fig. 4 d-e).

Description. Morphometrics and meristics in Table 10. Adult size moderate for members of this genus (larger than 40.0 mm in SL). Body stocky, robust, without conspicuous keels. Caudal peduncle round in cross section. Dorsal profile convex from tip of snout to dorsal-fin origin, except for almost straight portion anterior to parieto-supraoccipital. Dorsal-fin base straight and posteroventrally sloped, straight to slightly concave from posterior end of dorsal-fin base to caudal-fin origin. Ventral profile almost straight from snout tip to analfin origin, concave from this point to caudal-fin origin. Greatest body depth at dorsal-fin origin. Least body depth at middle of caudal peduncle. Posterior profile of caudal-fin margin pronounced concave. Head and snout broad, snout rounded to slightly pointed in dorsal view, body progressively narrowing posterior of pelvic-fin insertion. Snout region anterior to nares slightly concave, interorbital region convex. Upper margin of orbit slightly elevate. Eye dorsolaterally positioned. Iris operculum present.

Pectoral fin I,6, posterior-fin margin almost straight, when depressed tip extending beyond middle of pelvic fin. Posterior margin of pectoral-fin spine smooth in adults, juveniles with serrae along distal half of pectoral-fin spine. Pectoral-fin axillary slit present, located below ventral margin of cleithral process. Pelvic fin i,5. Tip of depressed fin almost reaching anal-fin origin in females, but extending far beyond anal-fin origin in males. Dorsal II,7. Dorsal-fin origin located slightly posterior of vertical through pelvic-fin origin. Dorsal-fin spinelet somewhat rounded. Anal fin 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 areas around base of paired fins. Rostral plate with posterior notch articulation with mesethmoid. Rostral plate thickened, with odontode-free band between dorsad and ventrad series of odontodes ( Fig. 38). Snout plates anterior to nares reduced, small unplated area at lateral portion between rostral plate and prenasal plates. Three rows of predorsal plates. Lateral line incomplete, with gap without pores along middle length of body. Median plate series complete, not truncated ( Fig. 4f). 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 row, pre-anal shield region formed by small to median size plates ( Fig. 8f). 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 slightly larger than those of surrounding areas, mostly in smaller specimens. Head, fin-spines, and body plates covered with odontodes, larger on anterior surface of all fin spines, and on ventral margin of rostrum, slightly enlarged on dorsal margin. Odontodes medially directed on pelvic-fin unbranched ray. Anterior margin of compound pterotic with median-to-large size perforations. Infraorbital canal entering infraorbital series via sphenotic. Lips roundish and papillose, posterior margin of lower lip fimbriate. Maxillary barbel present.

Premaxillary and dentary teeth slender proximally and flattened distally; bifid, major (medial) cusp rounded to spatulate, minor (lateral) minute pointed ( Fig. 27a).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, with slight median notch on the posterior margin of caudal-fin skeleton. Total vertebrae 27-29 (3 c&s). Color in alcohol. Ground color of dorsal and lateral surfaces of body light to dark brown. Dorsal and lateral surfaces of head darker than body, except for light area in ventrolateral region contrasting with dark blotches. Region anterior to nares lighter than surrounding areas, forming paired longitudinal light stripes from snout tip to posterior end of parieto-supraoccipital, bifurcating and inconspicuous posterior to that point. Midlateral surface of body darkish, forming darker brown wide longitudinal stripe above lateral line. Ventral surface of body pale yellow, sometimes with scattered round blotches, mostly on cheeks and belly. Unbranched rays of pectoral, pelvic, dorsal, and anal fins mostly brown pigmented, except for narrow lighter spots, forming striped pattern. Branched rays of these fins mostly hyaline except for darker transverse bands. Caudal fin mostly dark brown, except for pair of hyaline areas, somewhat triangular, on anterior portion of upper and lower lobes. Hyaline areas sometimes contacting each other at middle of caudal fin, forming hour-glass-like mark. Posterior portion of branched rays of caudal-fin hyaline. Unbranched rays of caudal fin with striped pattern of transverse light bands. In life, ground color of dorsum and flanks bright green ( Fig. 37).

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. Presence of a fleshy flap on medial portion of the first and second branched rays of pelvic fin. In juvenile males, flaps are smaller or absent. Males have a longer pelvic fin that extends far beyond the anal-fin origin, with the pelvic fin never reaching the anal-fin origin in females.

Distribution and habitat. Hisonotus vireo is widely distributed in the rio Jacuí basin from the eastern rio Gravataí and rio dos Sinos drainages to the lower portions of the western rio Jacuí drainage ( Fig. 32). In the rio Jacuí basin, the new species was not found in the southern tributaries or in the headwaters of rio Jacuí and rio Taquari drainages. This species inhabits medium to fast flow watercourses, with clear waters running over sandy or rocky bottoms, being collected in marginal or aquatic submersed vegetation. Hisonotus vireo is sympatric along almost its entire distribution with H. armatus .

Geographic variation. The specimens from arroio Tipiáia (MCP 26855 and MCP 41074) differ to a certain degree in pigmentation from other populations in the rio Jacuí basin. These specimens of arroio Tipiáia differ from other conspecifics by the darker pigmentation of caudal fin, which present reduced hyaline areas to complete dark brown in some specimens, contrasting with a pair of hyaline triangular areas on upper and lower lobes and no pigments at posterior portion of caudal fin rays. The condition observed in the caudal-fin pigmentation of specimens from arroio Tipiáia, resemble that of Hisonotus brunneus and H. heterogaster . However, when well defined, the hyaline areas in the specimens from arroio Tipiáia clearly are alike the triangular hyaline areas presented by other populations of H. vireo . A PCA was performed to compare morphometric data of that population to others of H. vireo , in rio Jacuí, rio Taquari, and rio dos Sinos (type locality). No discriminant differences were found between the populations of H. vireo , except when compared with the species H. brunneus ( Fig. 39). For these reasons, we tentatively identified these specimens from arroio Tipiáia as belonging to the species H. vireo , and restricted the type series to specimens collected close to the type locality.

Etymology. The specific epithet, vireo , from the Latin meaning “greenish”, in allusion to the greenish coloration of live specimens of this species.

38 Taxonomic review of Hisonotus from the laguna dos Patos system