Austrolebias queguay, Serra, Wilson S. & Loureiro, Marcelo, 2018

Serra, Wilson S. & Loureiro, Marcelo, 2018, Austrolebiasqueguay (Cyprinodontiformes, Rivulidae), a new species of annual killifish endemic to the lower Uruguay river basin, Zoosystematics and Evolution 94 (2), pp. 547-556: 547

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Austrolebias queguay

sp. n.

Austrolebias queguay  sp. n. Figs 1, 2A, B, G, 3A

Austrolebias  sp. in Loureiro et al. (2018)


ZVC-P 13576, male, 39.4 mm SL, Uruguay, Paysandú, wetlands of Río Queguay Grande, Estancia La Beba, 32°11 ’08” S, 57°26 ’08” W, M. Loureiro, A. Duarte, M. Zarucki, J. Bessonart and D. Hernández, Sep. 2011.


Uruguay: Paysandú: MHNM 3728, 2 males 29.9-33.6 mm SL, 2 females 27.4-33.3 mm SL, Río Queguay, 32°08 ’21” S, 57°26 ’19” W, M. Loureiro, A. Duarte, M. Zarucki, J. Bessonart and D. Hernández, Sep. 2011. MHNM 3729, 1 male 34.0 mm SL, 1 female 31.0 mm SL, same data of the holotype. ZVC-P 8657, 10 males 16.1-27.2 mm SL, 12 females 16.9-30.1 mm SL, Río Queguay, Rincón de Pérez, 32°08 ’23” S, 57°25 ’49” W, M. Loureiro and S. Clavijo, Aug. 2006. ZVC-P 11620, 37 males 22.8-39.4 mm SL (8 c&s 26.6-38.1 mm SL; 10 fixed in alcohol 95°, 21.9-28.4 mm SL, CAP 1193, GP 3353-3359 and GP 3364-3366), 60 females 24.2-40.1 mm SL (8 c&s 22.7- 37.4 mm SL; 4 fixed in alcohol 95°, 22.7-28.7 mm SL, CAP 1193, GP 3360-3363), Río Queguay, 32°08 ’21” S, 57°26 ’19” W, M. Loureiro, A. Duarte, M. Zarucki, J. Bessonart and D. Hernández, Sep. 2011. ZVC-P 11621, 28 males 22.1-34.9 mm SL (5 fixed in alcohol 95°, 22.1-27.7 mm SL, CAP 1181, GP 3367-3371), 33 females 21.2-29.9 mm SL (5 fixed en alcohol 95°, 23.4-27.8 mm SL, CAP 1181, GP 3372-3376), Río Queguay, 32°07 ’26” S, 57°30 ’45” W, M. Loureiro, A. Duarte, M. Zarucki, J. Bessonart and D. Hernández, 8 Sep. 2011. ZVC-P 12460, 33 males 25.7-39.1 mm SL (2 c&s 32.4-39.1 mm SL; 4 fixed in alcohol 95°, 27.1-29.0 mm SL, CAP 1194, GP 3377-3380), 25 females 24.9-37.4 mm SL (2 c&s 27.2- 33.1 mm SL; 3 fixed in alcohol 95°, 24.9-26.5 mm SL, CAP 1194, GP 3381-3383), same data of the holotype.


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).


Morphometric data in Table 1. Largest examined male 39.4 mm SL; largest examined female 40.1 mm SL. Body orbicular and compressed. Maximum body depth between pelvic-fin origin and anal-fin origin in both sexes. Dorsal profile of head straight to slightly concave. Dorsal profile of body convex between head and posterior insertion of dorsal fin. Ventral profile of body convex between anterior margin of mandible and the origin of anal fin; base of anal fin straight in males and straight to concave in females. Upper and inner margin of caudal peduncle usually straight. Snout short and rounded.

Posterior end of anal and dorsal fins rounded; presence of short filaments in distal margin of anal-fin in males. Anal fin in females triangular shaped (anteromedian rays prolonged forming anterior lobe). Caudal fin rounded. Pectoral fin elliptical, posterior margin on vertical between 2nd to 5th anal-fin ray bases in males, and between pelvic-fin origin and urogenital papilla in females. Pelvic fins medially united between 50-80%, with posterior tip reaching between urogenital papilla and base of 4rd anal-fin ray in both sexes. Urogenital papilla in males partially attached (only tip of papillae free) to anal fin. Base of dorsal-fin origin anterior to the anal-fin origin in males, between 8th to 11th vertebrae and 7th to 10th neural spine; in females usually vertical to posterior to the anal fin origin, between 12th to 14th vertebrae and 10th to 13th neural spine. Origin of anal fin between pleural ribs 8th to 9th and vertebrae 10th and 12th in males: between pleural ribs 9th and 12th and vertebrae 12th and 15th in females. Dorsal fin rays 22-25 in males and 17-20 in females; anal-fin rays 24-27 in males and 21-24 in females. Caudal fin rays 20-25; pectoral fin rays 11-13; pelvic fin rays 5.

Scales cycloid. Trunk and head scaled, except ventral surface of head. Longitudinal series of scales 28-33, regularly arranged; transversal series 11-16 (N=29 and one specimen with 21 scales); circumpeduncular series 13-20. Anal-fin base without scales; caudal fin with three rows of irregularly arranged scales. Contact organs present in all analyzed males, 1 to 8 contact organs per scale (usually 1 or 2); contact organs present in first 6 upper rays of pectoral fins; no contact organs on unpaired and pelvic fins.

Cephalic neuromasts: supraorbital 13-23, parietal 0-4, anterior rostral 1-2 (usually 1), posterior rostral 0-2 (usually 1), infraorbital 1-3 + 18-27, preorbital 2-4, otic 2-5, post-otic 1-5, supratemporal 1-3 (usually 1), median opercular 1-2 (usually 1), ventral opercular 1-3, preopercular 19-29, mandibular 11-15, lateral mandibular 3-7.

Basihyal cartilage anteriorly widened, about 50-60% of total length of basihyal; anterior margin of cartilage usually concave or with little commissures. Second pharyngobranchial with 3-8 teeth and 3rd with 17-37. First branchial arch with 3-4 epibranchial spines and 10-12 hypobranchial. Dermosphenotic ossifications present only in 5 % of specimens analyzed; proximal radials 3-5 (usually 4); ventral process posttemporal well-developed. Total vertebrae 27-30.

Color in life.

Males (Fig. 2 A–B). Ground color of body bluish green, darker in dorsal region, with 8-15 light sky blue vertical bands. Some specimens with dark green spots in the middle of the flank. Pectoral and ventral region whitish. Opercle and preopercle intense sky blue. Iris yellow; dark vertical band crossing the eye. Pectoral fins hyaline with black margin and iridescent blue sub-marginal band; pelvic fins blue to green. Dorsal and anal fins greenish blue with light sky blue dots on base; distal margin of anal fin darker. Caudal fin greenish blue with disperse light sky blue dots present or not, distal margin hyaline.

Females (Fig. 3A). Ground color light brown, darker in dorsal region; sides of abdominal area yellow; pectoral and ventral region whitish. Black spots in central area of flanks present or absent, when present usually horizontally aligned; rest of the body with diffuse brown spots or vertical bands. Iris yellow; diffuse gray vertical band crossing the eye. Opercle and preopercle with sky blue reflections. Paired fins hyaline; unpaired fins yellowish at base to hyaline on distal margin, sometimes with diffuse brown spots or bars in the space between rays.

Geometrical morphometric analyses.

Canonical variate analyses discriminated A. bellotti  specimens from the other species along Root 1 (84.7 and 83.7% of total variation in males and females respectively, Figs 4-5), and partially discriminated A. queguay  specimens from the other species along Root 2 (10.2 and 11.8 % of total variation in males and females respectively, Figs 4-5). In both cases, but especially in females, shape changes along Root 1 were associated to a deeper body in A. bellotti  in relation to the other species.


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.


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).


All its known locations are within "Montes del Queguay", a permanent protection reserve under the control and regulation of the Uruguayan government, with an area of about 200 km2, but without a management plan ( MVOTMA 2018; Furthermore, projected land-use changes for surrounding areas for the next decade may result in increases in forestry for cellulose production purpose ( Brazeiro 2015), and wetlands are potentially vulnerable to hydric changes in the region. For these reasons, considering UICN criteria ( IUCN 2012), and until a formal assessment is done, A. queguay  , could be considered preliminarily as an 'Endangered Species’.


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).