Hisonotus armatus Carvalho, Lehmann, Pereira & Reis, 2008

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 : 23

Hisonotus armatus Carvalho, Lehmann, Pereira & Reis, 2008

Figs. 21 c-d, 23, and 27d

Hisonotus armatus Carvalho et al., 2008: 510 [original description, type locality: Brazil, Rio Grande do Sul, Pedro Osório, arroio Arambaré, about 5 km south of Vila Basílio on the road to Pedro Osório ].

Hisonotus nigricauda non (Boulenger, 1981). - Lucena et al., 1994 [listed].

Hisonotus sp. 3 . - Cramer et al., 2007: 54 [molecular phylogeny of Loricariidae ].

Hisonotus sp. 5 . -Reis & Carvalho, 2007: 84 [listed]. - Cramer et al., 2007: 54 [molecular phylogeny of Loricariidae ].

Diagnosis. Hisonotus armatus differs from all congeners except H. leucofrenatus , H. leucophrys , and Hisonotus notatus by the combination of having the anterior margin of the snout completely covered by odontodes, vs. anterior margin of the snout with a narrow or wide odontode-free band; and having large plates in the abdominal median series, usually comprising of one series of plates between the lateral abdominal plates, vs. abdominal median series of plates small, with several plate series irregularly arranged between the lateral abdominal plates. Hisonotus armatus differs from H. leucofrenatus and H. notatus by the presence on caudal fin of a series of light hyaline spots, forming one or more vertical light bands ( Fig. 21 c-d), vs. a rounded hyaline blotch or no hyaline area in the midventral portion of caudal fin ( Fig. 21 ab). Further differs from H. leucofrenatus and H. notatus by the color pattern of dorsal surface of the head, which is covered by vermiculate and ovoid white and dark spots, vs. dorsal surface of the head plain dark to light brown. Hisonotus armatus differs from H. leucophyrs by the absence of a conspicuous tuft of odontodes on parieto-supraoccipital tip, vs. presence of a conspicuous tuft of odontodes on parietosupraoccipital tip, and by the presence of comparatively narrower light stripes on posterodorsal portion of head, vs. broader light stripes on the posterodorsal surface of the head.

Description. Morphometrics and meristics in Table 6. This species was recently described by Carvalho et al. (2008) and will not be redescribed here.

Distribution and habitat. Hisonotus armatus is widely distributed in the laguna dos Patos system ( Fig. 24). This species inhabits slow to median flowing watercourses, with clear to brown waters over sandy bottom and is found in marginal or submerged aquatic vegetation. Hisonotus armatus is sympatric through its distribution with H. laevior . It was also collected together with H. nigricauda in some localities of the lago Guaíba drainage, with H. vireo in the rio Jacuí drainage, and with H. notopagos in the upper rio Camaquã drainage.

Material examined. In addition to the material listed in Carvalho et al. (2008) the following specimens were examined: All from laguna dos Patos system, Rio Grande do Sul, Brazil. MAPA 2624 , 10 , 21.9 -38.0 mm SL, Gravataí , arroio Passo dos Ferreiros. MNRJ 25583 , 22 , 11.2-37.8 mm SL, Barra do Ribeiro , rio Guaíba at mouth of arroio Ribeiro. MNRJ 25611 , 16 , 20.8-28.5 mm SL, Porto Alegre , rio Guaíba north of Ponta dos Quatis. MCN 6456 , 1 , 39.4 mm SL, Três Coroas , arroio José Velho between Canastra Baixa and linha Café Alta. MCN 14236, 8 , 14.6-21.8 mm SL, Canela, rio Paranhana at Larangeiro Dam, 29º23’54”S 50º45’26”W. MCN 14795, 1 , 33.5 , Canela, arroio Casca northeast of UHE Canastra, 29º23’53”S 50º44’37”W. MAPA 1752 , 6 , 15.0-42.0 mm SL, São Sebastião do Caí , left margin of rio Caí. MCP 41549, 4 , 12.8 -19.0 mm SL, Cotiporã , rio Carreiro on road between Dois Lageados and Cotiporã, 28º59’43”S 51º45’16”W. MCP 43107, 3 , 28.3-30 mm SL, Nova Roma do Sul, rio das Antas downstream to hydroeletric plant UHE Castro Alves. MCP 43549, 1 , 29.2 mm SL, Faria Lemos, córrego Pedrinho near Alcântara, 29º05’31”S 51º37’23”W. MCP 44023, 1 , 35.2 mm SL, Bento Gonçalves, rio das Antas near to hydroeletric plant UHE 14 de Julho, 29º04’S 51º40’W. UFRGS 9974 , 4 , 28.6- 40.3 mm SL, Veranópolis, rio da Prata downstream to hydroeletric plant PCH Jararaca, 28º56’S 51º26’W. MCN 8071 , 1 , 19.0 mm SL, Triunfo, rio Jacuí at south margin of Ilha das Cabras .