The species was described in a paper from Hrbek et al. in 2005 that was set up to make a complete revision of the genus. In that major paper it was mentioned together with 3 other new species and in which A. myersi was removed from synonymy to A. limnaeus. DNA studies showed the differences in the species. The results where supported by the supposed development of the region in millions of years in agent history. See the PDF from this work at the bottom of this page.

The species was named in honor of Ing. Oscar Leon Mata, a Venezuelan scientist well known for his work on the Killies and other genera in his country.

The type locality is in Venezuela, Zulia collected in a temporary pond 5 km north of Campo Mara, collected on 25 June 1972 by J. E. Thomerson. Other sites are Venezuela, Zulia, Libertad, Caño antes de la Hacienda Las Mercedes, collected 22 July 1974, by C. Lilyestrom, D. Spiers, V. Sabril. Also from Venezuela, Zulia, Perijá, Saliendo de la población de Sartaneja, 10° 6´ 35” N, 72° 19´ 7” W by O. Leon. Further from Venezuela, Zulia, Préstamo cerca de la Hacienda el Japon, 30 June 1978, collected by D. Taphorn, E. Sutton. Diagnosis. This species is distinguished from all species of Austrofundulus by strong reddish-brownish background body colours observed in all sexually mature males. Relative to other species, the caudal peduncle is slender. The caudal fin is also large and slender with long extensions.

Females have a light greyish translucent caudal fin. The anal fin of males is patterned similarly to the dorsal fin. The background colour is brown reddish with a few large indistinct grey flecks in the basal half of the anal fin. The large grey flecks coalesce and become darker to form a blue-black distal margin. The base of the anal fin is creamy white, grading into this same colour on the belly. The anal fin often has a long extension. The anal fin of females is clear or light grey, with a few faint basal spots. The pectoral fins of males are uniformly translucent brownish-red with a greyish edge. The pelvic fins of males are similar to the pattern found on the anal fin. The background colour is brownish-red with a few large dull grey spots in the basal portion of the fin, although in some males the spots are absent. The base of the pelvic fin is almost white, and blends with the colour of the belly. Females have translucent, light grey pectoral and pelvic fins. The basic background colour is brownish-red with grey overtones. Few dull light grey to almost white spots are present in the posterior two thirds of the body, while the anterior one third of the body has several dark brown to black colored spots. Just above, and across the opercle, the spots are arranged into several diagonal rows. The ventrum is light grey to almost white, without spots, while the dorsum is darker than the rest of the body. In females, the sides are light brown to light grey colored. The body is not spotted. As in males, the abdomen of females is lighter than the rest of the body, while the dorsum is darker. An indistinct black bar passes through the eye of both sexes, passing obliquely through the eye onto the head posteriorly above and anteriorly below the eye. The iris is silver. The upper portion of the head is dark grey, the lower light grey to cream. In females the head is predominantly grey or olive dorsally, and lighter ventrally. A few iridescent golden scales are present on the males’ opercle, which has an overall yellowish tone. For meristics and morphometrics see Table 7. Austrofundulus leoni attains up to 29.4 mm. SL with a mean length of 26.0 mm SL. Females reach up to 33.6 mm. SL with a mean length of 25.9 mm SL.

All Austrofundulus become robust fishes that need a tank of at least 50 litres and where one male and 2 or more females are kept together. Males can be very aggressive to each other and females can be aggressive to each other to.

They eat a lot of food and grow rapidly as they do not have much time in the wild to live there live and produce there eggs. Because the habitats are mostly open and sunny, water temperatures can get 35 C during the day. Than lower to 25 C in the night. There courtship is very turbulent and if females are fed properly the number of eggs can become enormous.

Normally the Austrofundulus need to dive into the soft clay bottom and the layer of clay need at least have a thickness of there body length or more. However, without a soft layer of clay, or an substitute of peat moss they spawn eggs also on the substratum. As I collected in Colombia the A. aff. myersi and the A. guajira I was running out of proper plastic bags because I was not prepared to catch such massive killies and so much of them. Therefore I took some big garbage- bags to put the fishes in. These bags were stored under the bed in my hotel room and as I opened the bag to the daily change of water hundreds of eggs were spawned and fertilised inside the bags.

If you store the eggs in peat it is wise to add some Maërl or other pH neutralizing materials to it. Clay will also do . There eggs are sensitive to acid environments and normal peat can become to acid during the many months of storage. The use of well boiled coco- peat has proved to be the best medium so far to me. Development can be vary from 30 days to 12 months depending the way we store them.

I separated some eggs (about 20 in total) in a very wet peat and wetted them after 30 days. Three fry hatched, the others didn't show any development yet. For sure, you can speed up the development by storing the eggs at 30 degrees Celsius or even higher.

The fry need direct life artemia nauplii and if fed 2 times a day and change water once a week, they grow within 4 to 6 weeks to an stage they can produce there first eggs already. Austrofundulus is one of the very few South American genera that accept all type of food, even dry food en also frozen hart. Be careful with the fat that comes with the hart, you need to cut that of very secure as the fat will make these animals become sick after a while because it causes constipation.

Max. size 8.0 cm.
Dorsal 15.5,
Anal 16.7,
D/A 6.0,
LL scale count (average)31.3
Pre- dorsal length to % SL – 66.8 %
Depth to % SL – 31.8 %

Hrbek T., D.C. Taphorn & J.E. Thomerson 2005. Molecular phylogeny of Austrofundulus Myers (Cyprinodontiformes: Rivulidae), with revision of the genus and the description
of four new species. Zootaxa, 825:25, figs. 12-13. (PDF)