History

Described in the genus Austrolebias nubium

Abstract by description: Two new species of Austrolebias are described based on specimens collected from temporary pools located in natural grassland landscape within the Araucaria Forest domain at exceptionally high altitudes (~1000 meters a.s.l.). Austrolebias botocudo sp. n. and Austrolebias nubium sp. n. occur, respectively, in drainages of upper rio Apuaê-Inhandava (upper rio Uruguay basin) and upper rio Taquari-Antas (upper rio Jacuí, Laguna dos Patos basin), in the Meridional Plateau of southern Brazil. Despite an intensive survey conducted in the area, only two populations of each species were recorded. Both new species occurs at altitudes that are among the higher recorded for species of the genus, and both are assigned to the subgenus Acrolebias. The new species described herein are easily distinguished for its congeners by the colour pattern of males, by presence of melanophores irregularly distributed in different parts of the body, contact organs cover the body and anal fins, position of fins related with vertebrae, by preopercular and mandibular series of neuromasts united, by a series of morphometric features and by larger maximum standard length. Austrolebias botocudo and A. nubium are distinguished from each other by colour pattern of males, length of contact organs in the flank and number of contact organs in scales of lateral line, dorsal profile of head, number of neuromasts in the preopercular + mandibular series, body depth in females, and by basihyal cartilage length. Additionally, we discuss the conservation status of the new species, and provided an identification key for the species of the subgenus Acrolebias. 

Diagnosis. Austrolebias botocudo differs from its congeners allocated in the subgenus Acrolebias by a unique male colour pattern consisting of body flank lilac grey with bluish white vertical bands (vs. flank pale yellowish brown, with dark brown bars in A. araucarianus; flank golden with purplish grey bars in A. carvalhoi; and flank dark bluish brown with yellowish golden or light grey vertical bands in A. nubium). The new species additionally differs from A. araucarianus and A. carvalhoi by males presenting melanophores irregularly distributed across the body (vs. melanophores absent in A. araucarianus and A. carvalhoi).

Austrolebias nubium, MCP 54457, holotype, male, 41.1 mm SL; (B) Austrolebias nubium, MCP 54458, paratype, female, 34.5 mm SL from upper rio Santana, a tributary of upper rio Taquari-Antas drainage, upper rio Jacuí basin, Laguna dos Patos hydrographic system, Bom Jesus, Rio Grande do Sul State, Brazil. 

Austrolebias botocudo differs from the remaining species of the subgenus Acrolebias, except from A. nubium, by presenting contact organs on anal fin in males (vs. contact organs absent). Austrolebias botocudo differ from A. nubium by the presence of discrete contact organs in the flank (vs. conspicuous contact organs), presence of generally only one contact organ by scale of lateral line (vs. two prominent contact organs by scale of lateral line), by presenting jaws slightly prognathous (vs. jaws short); by dorsal profile of head slight concave (vs. nearly convex), more neuromasts in the preopercular + mandibular series (36–43 vs. 26–35), a lower body depth in females (28.2–32.3 % SL vs. 32.6–37.8 % SL), and by presenting basihyal cartilage about 40–50% of basihyal length (vs. 60–70% of basihyal length). The new species differ from A. araucarianus by presenting neuromasts of the supraorbital series united (vs. first three neuromasts of the supraorbital series separated from the remaining neuromasts), preopercular and mandibular series of neuromasts united (vs. separated), by presenting pelvic fin well-developed (vs. pelvic-fin girdle rudimentary or absent), fewer scales in the longitudinal series (27–30 vs. 31–33), and by presenting more neuromasts in the ventral opercular series (2–4 vs. 1). Austrolebias botocudo differ from A. carvalhoi by presenting more neuromasts in the supraorbital (2–3+22–27 vs. 3+20) and lateral mandibular series (5–9 vs. 4), preopercular and mandibular series of neuromasts united (vs. separated), and by presenting basihyal cartilage about 40–50% of basihyal length (vs. 65% of basihyal length). 

Garcialebias nubium (new combination)

To breed most Austrolebias, you need a tank with about 10 to 25 liter water in it, a small jar or plastic container of about 10 to 15 cm high, a little bit of well-boiled peat moss, or coco-peat, and a water temperature between 18 and 24 C. It is wise to add a small filter to that tank and change the water regularly for 90 %. Bring one male and, if possible, two or more females in the tank and feed the fishes daily with live food like daphnia, red- and black mosquito larvae, and white worms. Austrolebias does not accept dry food quickly, and also, the prepared cow-heart is not preferred if live food is offered. If possible, breed this genus in larger tanks with more than one pair or trio and give some hiding places if you do so. When breeding with more than one male, you should also provide more than one spawning container. Every male must have one, and you will see they show interesting territorial behavior to attract females into their spawning place.

The male "flinders" around the female, displaying his fins high- up with the most intense colors. As the female is willing to spawn, she follows the male, pressing his head towards the layer of peat, and when the female contact the male's belly, both will dive into the peat layer. This layer should have a thickness of at least the length of the largest animal or, better, some deeper so they can dive entirely into it.

The spawning occurs during the whole fertile life of the fishes, starting at 5 to 6 weeks of age, till they become old and weak or die from the lack of water in their natural environment. This "end-of-life" will be within 8 to 11 months, depending on the temperature. Higher temperatures will trigger more rapid aging.

In the wild, Austrolebias live in colder environments during the wintertime. Temperatures in Uruguay, Paraguay, and Argentina can get very low. Incubation time usually is six weeks if stored at high temperatures ( 25 C.) and more extended if kept at lower temperatures. The development can last five to six months also. So it is wise to check the eggs regularly to see if the eyes inside the eggs are fully developed and the iris is well visible. When "eyed-up," put a part of the peat with the eggs in water at cool (ca. 18 C) temperature. If the fry usually hatches- and swims within a few hours, wet the rest of the peat. After hatching, feed the fry immediately with freshly born Artemia nauplii. A day or so later, I pour the water together with the fry off and place them in a well-filtered tank without any peat moss to grow up. Austrolebias are not used to strong currents, and juveniles can die if turbulence is too strong. The remaining peat will still have eggs inside that are not ready to hatch yet. Re-pack the peat and store it for some extra time. This hatching delay is nature's answer to short rain showers that fill pools only temporarily, followed by another dry period. Such an event would kill the entire population of the species in that area if all eggs were hatched with first rains. These (late) eggs will hatch later, sometimes very much later, and the fishes that were born earlier will eat these youngs.

As stated before, young's are growing fast and will produce their first eggs after 5 to 6 weeks already, if not even sooner. This breeding information applies to most Austrolebias. However, if the above Austrolebias- species have different behavior or extreme adult size, find these adaptions below in this chapter under <remarks>.

Remarks;

No data of reproduction on this new species are given, but it is likely they reproduce like most other Austrolebias of small to medium size.

Max. size 29.1–52.7 mm in males - female smaller.
Dorsal (average, male only ) 21–24,
Anal (average, male only ) 21–24,
D/A (average, male only ) 0.0,
LL scale count (average) 00.0
Pre- dorsal length to SL – 48.6–54.8 %
Depth to SL – 31.2–37.3 %
Vertebrae count (average) 00.0

Lanéz L.E.K., M.V. Volcan and L. Matchik 2021. Two new annual fishes (Cyprinodontiformes: Rivulidae) unexpectedly discovered in the highlands of southern Brazil. Zootaxa 4949 (3) 499-520, Fig. 4, Tab. 1. 

Alonso F., G.E. Terán, W.S. Serra Alanís, P. Calviño, M.M. Montes, I.D. Carcía, J.A. Barneche, A. Almirón, L. Ciotek, P. Giorgis, J. Casciotta, 2023. From the mud to the tree: phylogeny of Austrolebias killifishes, new generic structure and description of a new species (Cyprinodontiformes: Rivulidae) Zool. Journ. of the Linnean Society, XX, 1-30, Fig. 15, Tab. 2.