FIGURE 1
| Lateral view of A. Scleronema macanuda, new species, paratype (ZVC-P 9374; 74.5 mm SL) and B. S. milonga, new species, holotype (MCP 54165; 37.8 mm SL) showing the thick fleshy flap in the base of the maxillary barbel (red arrows), the skin flap in the posterior margin of the opercle (black arrows), the dorsal membrane in the caudal peduncle (white arrows), and the vertical black bar in the caudal fin (blue arrow).
FIGURE 2
| Ventral view of the autopalatine (au) and vomer (vo) of Scleronema operculatum (UFRGS 19654) showing the articulation ventrally located between these two bones (black arrow). Scale bar = 1 mm.
FIGURE 3
| Dorsal view of the autopalatine (au) and maxilla (ma) of Scleronema minutum (ZVC-P 12491) showing the arch-shaped process on its dorsal surface (black arrow). Scale bar = 2 mm.
FIGURE 4
| Geographical distribution of the genus Scleronema. Circles and squares indicate species of the S. minutum group and S. operculatum group, respectively. Some symbols represent more than one collection locality. AR = Argentina; BR = Brazil; PY = Paraguay; UY = Uruguay.
FIGURE 5
| Dorsal view of the head of A. Scleronema mate, new species, paratype (UFRGS 17418; 34.9 mm SL), B. S. ibirapuita, new species, paratype (UFRGS 27402; 49.4 mm SL), C. S. milonga, new species, paratype (LIRP 16775; 35.3 mm SL), and D. S. minutum (UFRGS 19651; 46.4 mm SL) showing the pores of the laterosensory system. “Ap” = additional pore.
FIGURE 6
| Scleronema guapa just after the fixation in formalin, holotype (UFRGS 23500; 36.4 mm SL), Brazil, Rio Grande do Sul State, Rosário do Sul, sanga Santo Antônio, tributary to rio Ibicuí da Armada, lower rio Uruguay.
FIGURE 7
| Scleronema guapa just after the fixation in formalin, paratype (UFRGS 18087, 32.0 mm SL), Brazil, Rio Grande do Sul, Rosário do Sul, sanga Santo Antônio, tributary to rio Ibicuí da Armada, lower rio Uruguay.
FIGURE 8
| Scleronema ibirapuita, new species, holotype (MCN 19470; 39.5 mm SL), Brazil, Rio Grande do Sul, Santana do Livramento, “Área de Proteção Ambiental (APA) Ibirapuitã”, rio Ibirapuitã Chico, rio Ibicuí drainage, lower rio Uruguay.
FIGURE 9
| Scleronema macanuda, new species, holotype (MCN 20230; 71.8 mm SL), Brazil, Rio Grande do Sul Sentinela do Sul, irrigation water channel draining to arroio Velhaco, laguna dos Patos system.
FIGURE 10
| Dorsal view of the head of A. Scleronema macanuda, new species, paratype (UFRGS 21635; 75.6 mm SL) and B. S. operculatum (UFRGS 19646; 56.1 mm SL) showing the pores of the laterosensory system.
FIGURE 11
| Specimens in life of Scleronema macanuda, new species, paratypes, (UFRGS 21635; A. 75.6 mm SL, B. 65.7 mm SL), Brazil, Rio Grande do Sul, Bagé, rio Piraí, tributary of rio Negro, lower rio Uruguay.
FIGURE 12
| Scleronema mate, new species, holotype (MCP 54183; 49.3 mm SL), Brazil, Rio Grande do Sul, Venâncio Aires, arroio Grande, tributary of arroio Castelhano, rio Taquari basin, laguna dos Patos system.
FIGURE 13
| Small specimens of A. Scleronema mate, new species, paratype (UFRGS 17616; 34.3 mm SL) and B. S. teiniagua, new species, paratype (LIRP 16776; 29.3 mm SL).
FIGURE 14
| Scleronema milonga, new species, holotype (MCP 54165; 37.8 mm SL), Brazil, Rio Grande do Sul, Dezesseis de Novembro, arroio Lageado Araçá, rio Ijuí drainage, lower rio Uruguay.
FIGURE 15
| Specimen just after the fixation in formalin of Scleronema milonga, new species, paratype (UFRGS 7685; 32.7 mm SL), Brazil, Rio Grande do Sul, São Nicolau, unnamed stream tributary to rio Ijuí, lower rio Uruguay.
FIGURE 16
| Scleronema minutum, lectotype of Trichomycterus minutus (BMNH 1891.3.16.84; 32.4 mm SL), Brazil, Rio Grande do Sul, São Lourenço do Sul, stream tributary to laguna dos Patos. Photograph taken by Sandra Raredon.
FIGURE 17
| Scleronema minutum (MCP 17514; 39.8 mm SL), Brazil, Rio Grande do Sul, São Lourenço do Sul, arroio São Lourenço, laguna dos Patos system.
FIGURE 18
| Specimens in life of Scleronema minutum (A. UFRGS 22100; 37.4 mm SL, Santana da Boa Vista, arroio das Neves, B. UFRGS 22128; 39.4 mm SL, arroio Igrejinha), Brazil, Rio Grande do Sul.
FIGURE 19
| Scleronema minutum, paratype of Pygidium angustirostris (BMNH 1944.6.20.1; 34.5 mm SL), Uruguay, Paysandú, cañada de las Piedras Blancas, tributary to río Queguay, lower rio Uruguay. Photograph taken by Sandra Raredon.
FIGURE 20
| Scleronema minutum, paratype of Pygidium angustirostris (MNRJ 3605; 32.4 mm SL), Uruguay, Paysandú, cañada de las Piedras Blancas, tributary to río Queguay, lower rio Uruguay.
FIGURE 21
| Scleronema operculatum (UFRGS 18086; 40.0 mm SL), Brazil, Rio Grande do Sul, Rosário do Sul, sanga Santo Antônio, tributary to rio Ibicuí da Armada, lower rio Uruguay.
FIGURE 22
| Specimen in life of Scleronema operculatum (UFRGS 18086; 42.3 mm SL), Brazil, Rio Grande do Sul, Rosário do Sul, sanga Santo Antônio, tributary to rio Ibicuí da Armada, lower rio Uruguay.
FIGURE 23
| Scleronema operculatum, paratype (FMNH 58520; 58.6 mm SL), Brazil, Rio Grande do Sul, Cacequi, rio Cacequi, tributary to rio Santa Maria, rio Ibicuí basin, lower rio Uruguay. Photograph taken by Sandra Raredon.
FIGURE 24
| Scleronema operculatum, holotype (FMNH 58080; 65.9 mm SL), Brazil, Rio Grande do Sul, Cacequi, rio Cacequi, tributary to rio Santa Maria, rio Ibicuí basin, lower rio Uruguay. Photograph taken by Sandra Raredon.
FIGURE 25
| Original drawings published by Eigenmann (1918Eigenmann CH. The Pygidiidae, a family of South American catfishes. Mem Carnegie Museum. 1918; 7(5):259-398.): A. lateral view of the holotype of Scleronema operculatum, FMNH 58080, (plate 44; fig. 1); B. neurocranium, suspensorium, opercular apparatus, and inferior jaw from dorsal view of one paratype of S. operculatum, FMNH 58520, (p. 282; fig. 2d-e); C. part of the distribution map (modified from original drawing) showing the occurrence area of Scleronema (dashed square) at that time (plate 36).
FIGURE 26
| Scleronema teiniagua, holotype (ZVC-P 14522; 45.2 mm SL) Uruguay, Artigas, arroyo Tres Cruzes, río Cuareím basin, lower río Uruguay.
FIGURE 27
| Specimen in life out of the water of Scleronema teiniagua (ZVCP 13763), Uruguay, Artigas, arroyo Catalán Grande at Paso Santiño, río Cuareim basin lower río Uruguay. Photograph taken by Sebastián Serra.
TABLE 1
| Species of Scleronema with authors, name-bearing types and type localities.
TABLE 2
| Morphometric data of Scleronema guapa, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
TABLE 3
| Distribution of pores of the laterosensory system for the species of Scleronema. Asterisks indicate the pattern present in the type specimens of Scleronema minutum and S. operculatum and the holotype for other species. Additional pores are present in the infraorbital line or posteriorly to the pore s6 of the supraorbital line.
TABLE 4
| Morphometric data of Scleronema ibirapuita, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
TABLE 5
| Morphometric data of Scleronema macanuda, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
TABLE 6
| Morphometric data of Scleronema mate, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
TABLE 7
| Morphometric data of Scleronema milonga, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
TABLE 8
| Morphometric data of Scleronema minutum (data of type specimens not included in the range of non-types). N = number of non-types; SD = standard deviation.
TABLE 9
| Morphometric data of Scleronema operculatum (data of type specimens not included in the range of non-types). N = number of non-types; SD = standard deviation.
TABLE 10
| Morphometric data of Scleronema teiniagua, new species (data of holotype included in the range). N = number of specimens; SD = standard deviation.
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