Hoplias australis, Oyakawa & Mattox, 2009

Oyakawa, Osvaldo T. & Mattox, George M. T., 2009, Revision of the Neotropical trahiras of the Hoplias lacerdae species-group (Ostariophysi: Characiformes: Erythrinidae) with descriptions of two new species, Neotropical Ichthyology 7 (2), pp. 117-140 : 119-122

Hoplias australis , new species

Fig. 2

Holotype. BRAZIL. Santa Catarina State. Uruguay basin: MCP 40175, 220.0 mm SL, rio das Antas, rio do Ouro drainage, on Formosa do Sul-Irati road, Formosa do Sul , 26º38’55’’S 52º48’05’’W, 25 Jan 2006, C. A. Lucena, E. Pereira, V. Bertaco & J. P. Silva.

Paratypes. ARGENTINA. Misiones. Uruguay basin : MCP 13318, 2 , 41.9-42.2 mm SL, arroyo Itacaruaré , 27º53’S 55º17’W, 28 Jun 1989, E. Lerner ; MCP 13320, 1 , 59.3 mm SL, arroyo Santa Maria , 27º56’S 55º27’W, 28 Jun 1989, E. Lerner . BRAZIL. Rio Grande do Sul State. Uruguay basin . MCP 18561, 1, 200.6 mm SL, rio Dourado between Três Barras and Mariano Moro , Mariano Moro ,

21 Sep 1995, E. Filho, V. Schulz, S. Meurer & P. Iaczinski; MCP 19344, 1 , 64.5 mm SL, rio Uruguay near mouths of rios Canoas and Pelotas , 27º36’ 22”S 51º27’40”W , 13 Nov 1996, E. Pereira, J. Silva & R. Reis; MZUSP 99307 , 1, 225.3 mm SL, rio Uruguay, nearly 3 km from the Salto do Yucumã , Parque Estadual do Turvo , 27º08’13”S 55º31’55”W , 29 Oct 1991, L. Camara, L. Hanh, T. Melo & E. Silva; MZUSP 39791 , 1, 166.2 mm SL, arroio Lageado União in Linha dos Lima , Palmitinho , 22 Dec 1985, L. Malabarba, R. Reis & S. Mallmann; UFRGS 4940 , 2 , 98.9-151.7 mm SL, rio Cerquinha, São José dos Ausentes , 7 Apr 2000, Equipe Ictio UFRGS; UFRGS 7064 , 1 , 59.1 mm SL, stream on the road to Pirapó, São Nicolau , 5 Mar 2005, M. Azevedo, J. Ferrer, L. Malabarba & C. Oliveira. Santa Catarina State. Uruguay basin: MCP 12090, 1, 243.8 mm SL, rio Jacutinga, on Seára-Concórdia road, Concórdia , 22 May 1988, R. Reis, E. Pereira, P. Azevedo & A. Bergmann; MCP 12410, 2 , 217.1 - 234.6 mm SL, same locality , 2 Oct 1988, E. Pereira, A. Bergmann, P. Azevedo & A. Ramires; MCP 12741, 1, 211.7 mm SL, rio Canoas, on Abdon Batista-Anita Garibaldi road, Campos Novos , 11-12 Nov 1988, C. Lucena, E. Pereira, P. Azevedo & A. Ramires ; MCP 13146, 1, 253.6 mm SL, same locality , 30-31 Mar 1989, A. Bergmann, E. Pereira, P.Azevedo,A. Ramires & M. Vargas; MCP 18516, 2 , 140.0- 227.1 mm SL, rio Riacho Grande, on Piritiba- BR 153 road, Concórdia , 17 Sep 1995, E. Filho, V. Schulz , S. Meurer & P. Iaczinski; MCP 18820, 1, 199.8 mm SL; MCP 18821, 1, 198.8 mm SL, same locality , 29 Jul 1995, same collectors; MCP 18923, 2 , 114.3 - 176.8 mm SL, same locality , 11 Jan 1996, same collectors; MCP 20847, 7 , 25.2-37.2 mm SL, arroio Lageado Grande, 3 km Northwest of Linha Santana, Santa Helena , 26º53’35”S 53º36’4”W , 27 Jan 1998, C. Lucena, M. Lucena, E. Pereira & J. Pezzi; MCP 20860, 1 , 45.1 mm SL, rio Jundiá, on São Pedro-Tunápolis road, 27º01' 17”S 53º38’58”W , same date and collectors; MCP 20866, 1, 120.9 mm SL, Arroio da Taipa, on Mondaí-Itapiranga road, Mondaí 27º07’46”S 53º28’27”, same date and collectors; MCP 40088, 1 , 56.1 mm SL, rio Lageado Sertão, under bridge of BR 158 road, Cunha Porã , 27º02’42”S 53º13’33”W , 25 Jan 2006, V. Bertaco, C. Lucena, J. Pezzi & E. Pereira ; MCP 40093, 1 , 32.9 mm SL, rio Burro Branco , border between Serra Alta and Sul Brasil, 26º41’12”S 52º49’2”W , same date and collectors; MCP 40117, 1 , 34.9 mm SL, rio Pesqueiro, on Irati-Três Amigos road, Irati , 26º39’39”S 52º55’34”W , same date and collectors; MZUSP 99306 , 1, 210.4 mm SL, rio Saudade, bridge after town of Modelo towards BR 282 , Modelo , 26º47’10”S 53º2’43”W , same date and collectors; MCP 41287, 7 , 32.9-87.5 mm SL, collected with the holotype; UFRGS 7531 , 2 , 246.6 - 252.9 mm SL, rio Jacutinga, downstream from water capture, Concórdia , 30 Oct 2004, J. Scalcon. URUGUAY. Cerro Largo. Uruguay basin: MCP 9909 , 1 , 352.0 mm SL; MCP 9910 , 1, 443.9 mm SL, rio Negro, Arreria , 31º50’S 54º28’W , 19 May 1984, C. Lucena .

Diagnosis. The number of pores of the laterosensory canal along the ventral surface of dentary distinguished Hoplias australis from H. lacerdae (always 5 vs. 6-8 pores, respectively). The possession of an anterior profile of the head rounded in lateral view distinguished H. australis from H. brasiliensis and H. intermedius , which have the anterior profile of head angular. Hoplias australis can be further distinguished from H. curupira in the number of scales along lateral line (40-45 vs. 34-39 respectively).

Description. Morphometric data presented in Table 1. Body cylindrical, deeper than wide. Greatest body depth at vertical through third scale anterior to dorsal-fin origin in specimens smaller than 90 mm SL, and through sixth scale anterior to dorsal-fin origin in larger specimens (ca. 220 mm SL).Anterior profile of head rounded in lateral view, but more angular in specimens smaller than 40 mm SL. Dorsal profile of head varying from slightly convex in specimens smaller than 40 mm SL to almost straight in larger individuals. Dorsal margin of orbit at horizontal through dorsal profile of head in specimens smaller than 40 mm SL, but not reaching dorsal profile of head in specimens larger than 90 mm SL. Dorsal profile of body convex from vertical through first series of scale to dorsal-fin origin; slightly straight and posteroventrally inclined along dorsal-fin base; slightly concave from vertical through base of last dorsal-fin ray to origin of dorsal most procurrent caudal-fin ray. Latter portion of profile slightly straighter in specimens smaller than 90 mm SL. Ventral profile of lower jaw distinctly angular in region of dentary symphysis, straight to slightly convex from vertical through anterior nostril to posterior margin of lower jaw. Medial margins of contralateral dentaries approximately parallel ( Fig. 1 a-c). Ventral profile of body slightly convex to pelvic-fin origin; approximately straight from latter point to anal-fin origin; straight and posterodorsally inclined along anal-fin base; slightly concave to straight from base of last anal-fin ray to anterior most ventral procurrent caudal-fin ray.

Upper jaw usually as long as lower jaw, but slightly shorter in some specimens. Posterior portion of maxilla dorsally enlarged and extending medially to anterior margins of second and third infraorbitals. Upper and lower lips fleshy with short skin projections covering canines externally. Anterior nostril tubular with anterior slit along its distal half. Anterior and posterior nostrils situated along horizontal through center of orbit, anterior nostril located at point two-thirds of orbital diameter from anterior margin of orbit. Posterior nostril situated closer to anterior nostril than to anterior margin of orbit. Eye proportionately larger in smaller specimens. Infraorbital bones well developed and horizontally elongate. Infraorbitals 3, 4, and ventral portion of 5 partially covering preopercle. Ventral margin of infraorbital 3 convex. Posterior margin of infraorbital 4 relatively straight and margins of infraorbitals 5 and 6 slightly convex. Small specimens (ca. 90 mm SL) with infraorbital 3 barely reaching orbital rim and proximal portions of infraorbitals 2 and 4 almost in contact with each other. Larger specimens (ca. 220 mm SL) with infraorbitals 3 and 5 completely excluded from orbital rim and infraorbital 4 barely reaching rim.

Teeth in both jaws conical or canine. Premaxillary teeth in single row. First premaxillary tooth large canine, second, seventh and ninth teeth medium sized. Eighth tooth canine and almost as large as anterior most premaxillary canine in large specimens (ca. 220 mm SL). Third to sixth premaxillary teeth small. Maxilla with single row of approximately 30 relatively small teeth. Dentary with anterior external row of teeth and posterior internal row. External series with three small anterior teeth followed by two well-developed canines, with posterior one larger. Posterior canine followed by 11 conical teeth, some half size of anterior most dentary canine. Internal series beginning proximate to small conical tooth posterior to last conical tooth of external series and composed of approximately 12 very small teeth.Accessory ectopterygoid and ectopterygoid toothed; latter with series of small conical teeth along its ventrolateral margin and many smaller viliform teeth medially along its ventral surface. Endopterygoid edentulous.

Distal margins of all fins rounded. Total dorsal-fin rays 12-14 (n = 22; ii,10-12; mode: ii,11, n = 11). Dorsal fin located at midbody, its origin at vertical through approximately second scale anterior on series along pelvic-fin origin. Length of longest dorsal-fin rays two-thirds of body depth. Anal-fin base short. Total anal-fin rays 9-11 (n = 21; ii,7-9; mode: ii,8, n = 12). Tips of longest rays of depressed dorsal fin not extending beyond vertical through anal-fin origin. Total pectoral-fin rays 11-13 (n = 22; i,10-12; mode: i,11, n = 9). Pectoral-fin origin located at vertical through posterior region of opercle. Tip of pectoral fin separated from pelvic-fin origin by four to six scales, and falling short of vertical through dorsalfin origin. Pectoral, pelvic and anal fins of similar sizes. Pelvicfin rays i,7-8 (n = 22, i, 8 in one specimen). Pelvic-fin origin situated at midbody and approximately three scales posterior of vertical through dorsal-fin origin. Tip of pelvic fin separated from vertical through anal-fin origin by three scales in specimens smaller than 90 mm SL, and by up to eight scales in larger specimens (ca. 220 mm SL). Caudal-fin rays i,15,i (n = 9).

Well-developed, imbricated cycloid scales along body. Dorsal scales begin in series at posterior margin of parietals and overlap supraoccipital spine. Last vertical series of scales on caudal peduncle forming slightly convex arch on caudalfin base. Anterior margin of scales with small recess and posterior margin rounded. Approximately twelve radii extending from center of scale to its anterior margin and around twenty-two radii, some anastomosed, extending from center of scale to its dorsal, posterior and ventral margins. Lateral line straight and complete, extending from posteroventral margin of supracleithrum to posterior most scale in body. Lateral line with 40-45 perforated scales (n = 38, 44 in one specimen and 45 in one specimen; mode: 41, n = 12) ( Table 2). Lateral-line scales with single laterosensory canal. Longitudinal series of scales between lateral line and dorsalfin origin 4.5-5.5 (n = 21; mode: 4.5, n = 15). Longitudinal series of scales between lateral line and pelvic-fin origin 3.5- 5.5 (n = 20; mode: 4.5, n = 18). Longitudinal series of scales around caudal peduncle 19-20 (n = 21; mode 20, n = 20).

Approximately 12 gill rakers on first epibranchial, most in form of small denticulated plates. Lower branch of first branchial arch with five more elongate rakers and approximately 10 plate-like rakers (n = 9). Laterosensory canal along ventral surface of dentary always with five pores (n = 43, Table 3).

Color in alcohol. Ground coloration of head and body dark brown or dark grey, darker dorsally and paler ventrally, latter region white or dark yellow to light brown in most specimens. Dark brown midlateral stripe along lateral line weakly evident in specimens smaller than 90 mm SL and almost absent in larger specimens (ca. 220 mm SL).Approximately seven dark blotches along lateral line with width of blotches about six longitudinal series of scales; pattern more conspicuous in specimens smaller than 90 mm SL. Dark coloration of body obscuring dark midlateral stripe and blotches in larger specimens. Three or four dark blotches present along dorsal surface of body. Some specimens with several small dark spots located on dorsolateral portion of body. Dorsal surface of head dark brown or grey. Numerous small black spots on dorsal surface of head of several specimens. Lips dark grey, with small vertical light bands in specimens smaller than 40 mm SL. Coloration of infraorbital region similar to that of dorsal surface of head. Some specimens with one or two dark stripes radiating posteriorly from eye across opercular series. Ground coloration of opercular series similar to rest of head. Opercle membrane usually as dark as opercle, but slightly lighter in some specimens.

All fins light brown or grey with dark spots on rays and interradial membrane forming pattern of irregular dark stripes. Dark and light stripes of similar width in specimens smaller than 90 mm SL, with dark stripes wider than light ones in larger specimens. Ventral surfaces of pectoral and pelvic fins either lighter or with pattern similar to that of dorsal surface but less conspicuous.

Distribution. Throughout rio Uruguay basin, including its tributary rio Negro ( Fig. 3 ).

Etymology. The name australis , an adjective, refers to the southern range of this species, one of the southern most in the genus.

Remarks. Valenciennes (1846) described Macrodon auritus based on one specimen collected in Montevideo, Uruguay, from rio Uruguay basin. It is not clear, however, from the original description whether the species belongs to the Hoplias lacerdae group or to either of the two taxa of this group documented from the rio Uruguay in this study. Unfortunately, the type specimen of M. auritus has not been located in MNHN, contrary to the other type specimens of the Erythrinidae described in Valenciennes (1846) [P. Pruvost, pers. comm.]. Macrodon auritus is therefore considered a nomen dubium ( ICZN, 1999).

Two species of Hoplias lacerdae group, H. australis and H. lacerdae , occur in sympatry and syntopy in the rio Uruguay basin, and were collected together at some localities. Hoplias lacerdae also occurs in the rio Ribeira de Iguape (see below), and H. australis is, thus, the only Hoplias species apparently endemic to the rio Uruguay basin. Judging from the amount of material in museum collections, H. australis is much less common in the rio Uruguay than H. lacerdae .

Figures

Fig. 2. Hoplias australis, holotype, MCP 40175, 220 mm SL, rio dasAntas, Formosa do Sul, Santa Catarina State, Brazil.

Fig. 1. Ventral view of head of (a) Hoplias curupira, MZUSP 24403, 55.5 mm SL; (b) H. curupira, MZUSP 24403, 92.2 mm SL; (c) H. curupira, MZUSP 24403, 162.2 mm SL and (d) H. malabaricus, MZUSP 90416, 101.7 mm SL.

Fig. 3. Map of South America showing geographic distribution of species of the Hoplias lacerdae group based on material examined in this study. Some symbols may represent more than one lot. Numbers indicate type localities of (1) Hoplias australis (squares); (2) H. brasiliensis (losanges); (3) H. curupira (triangles); (4) H. intermedius (dots); and (5) H. lacerdae (inverted triangles).