Hypostomus commersoni Valenciennes, 1836

Garavello, Julio César, Britski, Heraldo Antônio & Zawadzki, Claudio Henrique, 2012, The cascudos of the genus Hypostomus Lacépède (Ostariophysi: Loricariidae) from the rio Iguaçu basin, Neotropical Ichthyology 10 (2), pp. 263-283 : 267-269

Hypostomus commersoni Valenciennes, 1836 Fig. 2

Hypostomus commersoni Valenciennes, 1836 :(266) 495-497 (type locality: rio de La Plata); Valenciennes, 1847:8 (ref.); Isbrucker, 1980:21 (ref.); Weber, 1986:994, rio da Prata (ref.); Reis et al., 1990:736 (lectotype, rio da Prata); López & Miquelarena, 1991:20 (ref.); Garavello et al., 1997:79 (rio Iguaçu); Weber, 2003:357 (ref.); Zawadzki et al., 2005:272 (upper rio Paraná, allozymes); Carvalho & Bockmann, 2007:92 (medium and lower rio Paraná, rio Uruguai).

Hypostomus aff. commersoni : Baumgartner et al., 2006:3 (Salto Osório reservoir, rio Iguaçu ; check list).

Hypostomus aff. commersonii : Zawadzki etal., 1999:96 (allozymes and morphometrics); Zawadzki et al., 2001:914 (isozymes).

Plecostomus commersonii : Günther, 1864: 232 (rio Grande); Regan, 1904: 206 (rio da Prata); Miranda Ribeiro, 1907:188 (Iporanga, São Paulo); Eigenmann, 1910:404 (ref.); Nichols, 1918: 414 (São Paulo); Gosline, 1945: 78 (ref.); Fowler, 1954:179 (La Plata).

Plecostomus commersoni : Miranda Ribeiro, 1911:50 (rio Paraná); Miranda Ribeiro, 1918:710 (São Paulo).

Material examined. Uruguay: rio de la Plata: MNHNA.9444, 425.0 mm SL, syntype . Brazil: Paraná State: LISDEBE 2652 , 2 , 147.0- 193.0 mm SL, rio Iguaçu, Salto Segredo reservoir, Municipality of Mangueirinha , Apr 1993, Nupélia. MHNCI 9061 , 1, 148.7 mm SL, rio Iguaçu , Municipality of Lapa , 25º46’10”S 49º16’23”W, 20 Sep 2001, F. X. Wegbecher & I. A. Rodriguez. NUP 552 , 3 , 216.0-253.0 mm SL, Cavernoso reservoir, rio Cavernoso , tributary of rio Iguaçu , Municipality of Candói , 25º29’30”S 52º12’52”W, 23-24 Aug 1999, Copel. NUP 596 , 2 , 67.9-287.5 mm SL, córrego Passo do Aterrado , tributary of rio Jordão , Municipality of Foz do Jordão , 25º45’S 52º10’W, 17 Nov 1997, Copel. NUP 1592 , 3 , 232.4 - 244.2 mm SL, downstream Salto Segredo reservoir, rio Iguaçu , Municipality of Mangueirinha / Reserva do Iguaçu , 25º45’S 52º05’W, 3 Feb 1995, Nupélia. NUP 1627 , 2 , 196.2 - 210.3 mm SL, upstream Salto Caxias reservoir, rio Jaracatiá , tributary of Iguaçu, Municipality of Capitão Leônidas Marques / Nova Prata do Iguaçu , 25º32’12”S 53º29’11”W, 28 Oct 1999, Nupélia. NUP 2541 , 4 , 123.6 - 270.6 mm SL, Foz do Areia reservoir, rio Iguaçu , Municipality of Cruz Machado / Bituruna, 26º00’S 51º37’W, 27 Oct 1998, Nupélia. NUP 2991 , 9 , 135.4 - 249.9 mm SL, Foz doAreia reservoir, rio Areia , tributary of rio Iguaçu , Municipality of Cruz Machado / Bituruna, 26º00’S 51º37’W, 14 Nov 2000, Copel. NUP 2998 , 4 , 212.8 - 249.1 mm SL, Foz do Areia reservoir, rioAreia, tributary of rio Iguaçu , Municipality of Cruz Machado / Bituruna, 26º00’S 51º37’W, 16 Nov 2000, Copel. NUP 4587 , 1 , 271.0 mm SL, Salto Santiago reservoir, rio Iguaçu , Municipality of Saudade do Iguaçu / Rio Bonito do Iguaçu , 25º38’03"S 52º36’03"W, 1 Nov 2004, Gerpel. NUP 4588 , 2 , 155.5 - 189.9 mm SL, Salto Santiago reservoir, rio Iguaçu , Municipality of Saudades do Iguaçu / Rio Bonito do Iguaçu , 25º38’03”S 52º36’03”W, 1 Nov 2004, Gerpel. NUP 5838 , 2 , 66.3-182.9 mm SL, Jordão reservoir, rio Jordão , tributary of rio Iguaçu , Municipality of Foz do Jordão / Reserva do Iguaçu , 25º45’13”S 52º05’09”W, 15 Sep 1997, Copel. NUP 5890 , 1, 176.1 mm SL, Salto Segredo reservoir, rio Iguaçu , tributary of rio Iguaçu , Municipality of Mangueirinha / Reserva do Iguaçu , 25º45’S 52º05’W, Nov 2001, Nupélia. NUP 5891, 158.6 mm SL, Salto Segredo reservoir, rio Iguaçu , Municipality of Mangueirinha / Reserva do Iguaçu , 25º45’S 52º05’W, Jun 2002, Nupélia. NUP 5915 , 2 , 130.2 - 147.9 mm SL, Foz do Areia reservoir, rio Areia , tributary of rio Iguaçu , Municipality of Pinhão /Bituruna, 26º00’S 51º37’W, 6 Oct 1999, Nupélia. NUP 5916 , 1, 205.8 mm SL, Foz doAreia reservoir, rioAreia, tributary of rio Iguaçu , Municipality of Pinhão /Bituruna, 26º00’S 51º37’W, 24 May 2000, Nupélia .

Diagnosis. Hypostomus commersoni can be distinguished from the species of the H. cochliodon group of species, except H. hemicochliodon , by having bifid not spoon-shaped teeth and with the lateral cups not fused to the mesial one (vs. spoon-shaped teeth with lateral cups usually fused to the mesial one). It is also distinguished from the remaining congeners, except H. carinatus , H. hemicochliodon , H. hoplonites , H. plecostomus , H. tapijara , and H. watwata by having strong keels along each of the lateral series of plates (vs. lacking strong keels). From H. carinatus , H. hemicochliodon , H. hoplonites and H. watwata it is distinguished by having a higher number of teeth on each dentary, 23-53 (vs. 13-18 in H. carinatus , 7-23 in H. hemicochliodon , 12-21 in H. hoplonites , and 19- 29 in H. watwata ). It is further distinguished from H. watwata by having the upper and the lower unbranched caudal-fin ray length almost to just equaling predorsal distance length (vs. clearly surpassing this distance in adult individuals; e.g. In MNHN A.8919, syntype of H. watwata ). From H. tapijara it is distinguished by cleithral width 26.6- 35.7% in SL (vs. 23.5-27.2), by caudal peduncle depth 8.9- 10.4% in SL (vs. 8.0-9.0), and by dorsal-spine length 32.6- 45.0% in SL (vs. 27.6-34.3).

Description. Dorsal profile of head slightly curved from tip of snout to anterior orbit; supraoccipital profile high and curved to the dorsal-fin insertion. Head elevated and slightly compressed, totally covered by dermal bones with dense covering of odontodes.A conspicuous keel on posterior region of pterotic-supracleithrum behind orbit, followed by continuous keel of odontodes along each lateral series of plates to caudal peduncle; two inconspicuous and divergent keels from median region of supraoccipital; followed by dorsal series of plates along caudal peduncle, giving to upper caudal peduncle a quadrangular aspect. Snout narrow and compressed, covered by irregular series of small plates. Mesethmoid forming inconspicuous bulge from snout tip to upper region of orbit. Orbit elevated, almost lateral; orbit diameter 11.4-14.3% in head length. Posterior region of head between supraoccipital and dorsal fin formed by two pair of large plates followed by an unpaired nuchal plate enclosing the first dorsal-fin spinelet. Supraoccipital and pterotic-supracleithrum densely covered with odontodes; larger odontode rows on keels of pterotic-supracleithrum just behind orbit on each side. Dorsal profile of trunk arched at dorsal-fin insertion, slightly declining to caudal fin. Adipose-fin spine short, joined to dorsal caudal peduncle by a slim membrane.Dorsal, mid-dorsal, middle, and mid-ventral series of plates in bent plates forming a keel of hypertrophied odontodes from posterior region of scapular bridge to caudal fin; ventral series of plates moderately angled from posterior region of pelvic fin to lower trunk, giving to caudal peduncle a rectangular aspect. Maximum width slightly decreasing from scapular bridge to caudal fin in dorsal view. Dorsal fin II,7; its origin slightly anterior to vertical through pelvic-fin insertion; elongate, surpassing the adipose-fin spine when adpressed; its distal margin convex. Pectoral fin I,6; elongate, surpassing the pelvic-fin insertion; first ray with large odontodes at upper distal region; its distal margin almost straight. Pelvic fin i,5; surpassing half of anal-fin first ray; its distal border slightly convex. Anal fin, i,5; distal border slightly rounded. Caudal fin i,14,i; slightly concave, lower unbranched ray longer than upper.

Body covered by five longitudinal series of large plates, four of them forming conspicuous keels along whole body and with pungent odontodes on median region of each keel. Rostral margin of snout aciculate. Tip of snout covered by irregularly dispersed platelets and with odontodes extending to upper limits of supraoccipital and posterior pterotic-supracleithrum. Scapular bridge totally covered by small plates with odontodes covering practically whole abdomen; only a small naked area in front of each pelvic-fin insertion; two pair of small plates between anal-fin base and anus. Twenty eight plates in lateral line. Lips with dense papillae; labial barbel elongate and free from the labial border; 23-48 teeth on premaxilla and 24- 53 on dentary; teeth slender and long with internal cusps larger than external ones.

Color pattern. Ground color of head and trunk reddish dark brown, irregularly black spotted with small spots on head and larger and more spaced spots on dorsum. All fins dark brown and interradial membranes hyaline and irregularly black spotted with small spots; unbranched rays dark brown. Abdominal region light brown, usually without spots but some species exhibit dark spots.

Distribution. Known from Paraná-Paraguay basin, rio Iguaçu, rio Uruguay and coastal rivers from south Brazil. In the rio Iguaçu basin H. commersoni is found mainly in the main channel of the rio Iguaçu, where it was frequently captured in the several reservoirs from the rio Iguaçu as Foz do Areia, Jordão, Salto Caxias, Salto Santiago and Segredo reservoirs. Hypostomus commersoni was also captured in some direct tributaries of the rio Iguaçu as rios Cavernoso, Jaracatiá, and Jordão as well as, in a tributary of rio Jordão the córrego Passo do Aterrado.

Figures

Fig. 2. Hypostomuscommersoni, NUP 552, 216.0 mm SL, Cavernoso reservoir, rio Cavernoso, tributary of rio Iguaçu, Municipality of Candói, Paraná, Brazil.