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