[Ichthyology • 2019] Austrolebias ephemerus • A New Annual Fish (Cyprinodontiformes: Rivulidae) from the upper Rio Paraguai basin, Brazilian Chaco

Austrolebias ephemerus

Volcan & Severo-Neto, 2019

  DOI: 10.11646/zootaxa.4560.3.6

Abstract

A new species of Austrolebias belonging to the A. bellottii species group is herein described from the Brazilian Chaco, Mato Grosso do Sul state, constituting the northernmost record of the genus in Brazil, as well as the first record of this genus on the left bank of the Rio Paraguai. The new species is distinguished from all other species of the A. bellottii group by the following combination of characters: pectoral fin posterior margin reaching vertical between base of 4th and 7th anal fin rays in females, a high number of gill rakers in the first branchial arch, a lower head width in both sexes, and a small number of neuromasts in the preopercular series. Additionally, we provide information on ecology and the conservation status of the new species.

Keywords: Pisces, Austrolebias bellottii species group, seasonal pool, conservation, killifish

Matheus Vieira Volcan and Francisco Severo-Neto. 2019. Austrolebias ephemerus (Cyprinodontiformes: Rivulidae), A New Annual Fish from the upper Rio Paraguai basin, Brazilian Chaco.  Zootaxa. 4560(3); 541–553.  DOI: 10.11646/zootaxa.4560.3.6

[Ichthyology • 2018] Austrolebias queguay • A New Species of Annual Killifish (Cyprinodontiformes, Rivulidae) Endemic to the lower Uruguay River Basin

Austrolebias queguay

Serra & Loureiro, 2018  

  DOI: 10.3897/zse.94.29115  

Abstract
In this article we describe a new species of the annual fish genus Austrolebias from the lower Uruguay river basin. The fusion of the urogenital papilla to the first anal fin ray in males and the pigmentation pattern, indicates a close relationship with the clade formed by A. bellottii, A. melanoorus, and A. univentripinnis. The new species can be differentiated from those by the following combination of characters: presence of well-defined light bands contrasting with the sides of the body, the distal portion of the anal fin dark gray, pelvic fins dark bluish green and bases united at about 50–80% on their medial margins, pectoral fins with iridescent blue sub-marginal band, and general coloration of body bluish green. The new species can only be found in wetlands of the Queguay river, an area included in the Uruguayan protected areas system and represents so far the only annual fish species endemic to the lower Uruguay river basin.

Key Words: Austrolebias bellottii species group, Systematics, La Plata basin

Austrolebias queguay sp. n. 
Figure 2. A. paratype male (ZVCP 11620); B. non type male, not preserved (right side, photo flipped)

Figure 2. A. Austrolebias queguay sp. n. paratype male (ZVCP 11620); B. A. queguay non type male, not preserved (right side, photo flipped); C. i non preserved male; D. A. univentripinnis male (UFRGS 18064, right side photo flipped); E. A. melanoorus topotype male (ZVCP13651); F. Detail of pectoral and pelvic fins of A. melanoorus; G. Detail of pectoral and pelvic fins of  A. queguay.

Figure 3. A. Austrolebias queguay sp. n. female: paratype ZVCP 11620; B. A. bellottii female (ZVCP 11560); C. A. univentripinnis female (UFRGS 18066); D. A. melanoorus topotype female (ZVCP 13651).

Austrolebias queguay sp. n.

Austrolebias sp. in Loureiro et al. (2018)

Diagnosis: The new species differs from all the other species of the genus except Austrolebias bellottii, A. univentripinnis and A. melanoorus, by the presence of the urogenital papilla attached to the anal fin in males (vs. free from the anal fin). It differs from A. bellottii and A. univentripinnis by the presence of well-defined light blue bands contrasting with the sides of the body in adult males (vs. vertical rows of light blue dots) (Fig. 2); from A. melanoorus, by the presence of dark gray coloration of the distal portion of the anal fin in males (vs. distal portion of anal-fin black), pelvic-fins dark bluish green (observed in ventral view) and bases united at about 50–80% on their medial margins (vs. dark gray and united about 50% or less), pectoral-fins with iridescent blue sub-marginal band (vs. sub-marginal band absent), and general coloration of the body bluish green (vs. grayish sky blue).

 Figure 6. Geographic distribution of Austrolebias queguay sp. n. (orange dots, Uruguay river basin), A. bellottii (yellow dots, Paraná and Uruguay river basins), A. melanoorus (red dots, Negro and Yaguarón river basins), and A. univentripinnis (green dots, Yaguaron river basin). Orange star indicates type locality.

Figure 7. Type locality of Austrolebias queguay sp. n., wetlands of middle Queguay river basin.

Etymology: The specific name, queguay, is in reference to Queguay river basin, the type locality of the new species, treated as a noun in apposition to the generic name.

Distribution: Austrolebias queguay is endemic to the wetlands of middle Queguay river basin (30 meters above sea level), Paysandú Department, Uruguay, which flows to the lower Uruguay river (Fig. 6).

Ecology: As many species of the family Rivulidae, A. queguay presents an annual life cycle which includes drought resistant eggs and diapausing embryos. All species of Austrolebias are obligate annuals (Berois et al. 2016). In the Pampa biome there is not a defined dry season, so dried environments can be found between mid spring to early fall (depending on the year), when evaporation is higher than precipitations (Williams 2006; García et al. 2017). Austrolebias species can be found in small grassland ponds and seasonal floodplain wetlands; however the new species has been found so far only in the latter environments (Fig. 7).


 Wilson S. Serra and Marcelo Loureiro. 2018. Austrolebias queguay (Cyprinodontiformes, Rivulidae), A New Species of Annual Killifish Endemic to the lower Uruguay River Basin. Zoosystematics and Evolution. 94(2): 547-556.  DOI: 10.3897/zse.94.29115

[Ichthyology • 2017] Austrolebias camaquensis • A New Annual Fish of the Genus Austrolebias (Cyprinodontiformes: Rivulidae) from Rio Camaquã basin, Laguna dos Patos system, Brazilian Pampa

Austrolebias camaquensis 

 Volcan, Gonçalves & Lanés, 2017

 DOI:  10.11646/zootaxa.4338.1.7 

Abstract

A new species of Austrolebias is described from the middle course of the Rio Camaquã, Laguna dos Patos system, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species group, which is distinguished from the remaining congeners by the presence of a dark gray pectoral fin with bright blue iridescence in males. The new species is distinguished from all remaining species of the A. alexandri species group by the following combination of characters: presence of well-defined bright blue bars on the flank in males, shorter caudal fin length in males and females, contact organs in the first three rays of the pectoral fin in males, one to two post-optic neuromasts (rarely three), basihyal width of 50% of the length, and basihyal cartilage about 50–60% of the basihyal length. The recognition of this new species belonging to the A. alexandri group endemic of the middle course of Rio Camaquã and the recent discovery of Austrolebias bagual in the same general region reinforces the claim of the middle Rio Camaquã basin as an area of endemism for annual fishes and as such, a priority area for conservation in southern Brazil.

Keywords: Pisces, Austrolebias, killifish, Rio Camaquã basin, temporary wetland, threatened fish, conservation

 Matheus Vieira Volcan, Ândrio Cardozo Gonçalves and Luis Esteban Krause Lanés. 2017. A New Annual Fish of the Genus Austrolebias (Cyprinodontiformes: Rivulidae) from Rio Camaquã basin, Laguna dos Patos system, Brazilian Pampa. Zootaxa. 4338(1); 141–152. DOI:  10.11646/zootaxa.4338.1.7

[Ichthyology • 2016] Melanorivulus polychromus • A New Species of Killifish (Cyprinodontiformes: Rivulidae) from the rio São José dos Dourados Drainage, middle rio Paraná Basin, southwestern Brazil, with A Redescription of Melanorivulus apiamici

Melanorivulus polychromus

Nielsen, Neves, Ywamoto & de Aguiar Passos,  2016

Abstract

A new species of Melanorivulus is described from the middle rio Paraná basin, São Paulo state, Brazil. Melanorivulus polychromus, new species, is found in a tributary of the left bank of the rio Paraná basin, the rio São José dos Dourados. It differs from all congeners by the combination of a metallic green to light green ground colour in males, with 6-8 oblique red bars forming chevronlike rows, the chevron tips along the midline of the body pointing toward the head, and irregular narrow red lines and incomplete red bars along the lower half of the body. Melanorivulus apiamici, also endemic from the middle rio Paraná basin, is redescribed.

Nielsen, D.T.B., Neves, P.A.B.A., Ywamoto, E.V. and de Aguiar Passos, M. 2016. Melanorivulus polychromus, A New Species of Killifish from the rio São José dos Dourados Drainage, middle rio Paraná Basin, southwestern Brazil, with A Redescription of Melanorivulus apiamici (Cyprinodontiformes: Rivulidae). aqua, International Journal of Ichthyology. 22(2); 79-88. 

[Ichthyology • 2013] Spectrolebias brousseaui • A New Annual Fish (Cyprinodontiformes: Rivulidae: Cynolebiatinae) from the upper río Mamoré basin, Bolivia

Spectrolebias brousseaui  

Nielsen, 2013 
  DOI: 10.1590/S1679-62252013000100009  

ABSTRACT

Spectrolebias brousseaui is described from a temporary pool from the upper río Mamoré basin, Departamento Santa Cruz, Bolivia. The new species is distinguished from all congeners, by the overall dark blue coloration on the posterior two-thirds of body with bright blue iridescent spots vertically aligned in males. Spectrolebias brousseaui differs from all other species of the genus, except S. filamentosus, for having pelvic fins separated by a space (vs. pelvic fins in contact), long filaments at the tip of the dorsal and anal fins in males (vs. absence of filaments or presence only on dorsal fin in S. semiocellatus and S. inaequipinnatus, or the presence on the anal fin in S. chacoensis), and presence of contact organs on the scales of the flanks in males (vs. absence of contact organs on flanks in all remaining Spectrolebias species).

Key words: Phylogeny; Spectrolebias filamentosus; Temporary pool

Distribution. Known from the type locality in río San Pablo basin, a tributary of the río Mamoré, Departamento Santa Cruz, Bolivia.

Habitat. The type locality lies at the plateau area (316 m.a.s.l.), just southwest of Llanos de Mojos, which occupy much of the río Mamoré basin in Bolivia (see Loubens et al., 1992). Water temperature at the surface of the pool was 31ºC, while at the depth of 1 m, 22ºC. In the marginal area of the pool, at the depth of 15 cm, water temperature was 35ºC. Only small specimens of Trigonectes sp. were collected in marginal areas. Specimens of Simpsonichthys brousseaui were collected in the deepest areas, at about 1 m deep. The pool presented dark water, pH 6.8 and water hardness 80 ppm. Other fish species collected syntopically were Trigonectes sp.

Etymology. The specific name is in honor to Roger D. Brousseau, discoverer of the species.

Nielsen, D.T.B. 2013. Spectrolebias brousseaui (Cyprinodontiformes: Rivulidae: Cynolebiatinae), A New Annual Fish from the upper río Mamoré basin, Bolivia.

 Neotropical Ichthyology. 11(1); 81-84.  DOI: 10.1590/S1679-62252013000100009 

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RESUMO: Spectrolebias brousseaui é descrita de uma poça temporária localizada na região superior da bacia do río Mamoré, departamento de Santa Cruz, Bolívia. A espécie nova distingue-se de todos os congêneres pelo padrão de cor azul escuro nos dois terços posteriores do corpo com pontos azuis claros iridescentes alinhados verticalmente em machos. Spectrolebias brousseaui difere das outras espécies do gênero, exceto S. filamentosus, por ter as nadadeiras pélvicas separadas por um espaço (vs. nadadeira pélvicas juntas), longos filamentos nas extremidades das nadadeiras dorsal e anal em machos (vs. ausência de filamentos ou a presença apenas na nadadeira dorsal em S. semiocellatus e S. inaequipinnatus, ou pela presença de filamentos na nadadeira anal em S. chacoensis), e presença de órgão de contato nas escamas do flanco em machos (vs. ausência)