Argolebias guarani

Etymology: The name guarani is erected in honor of the Guaraní indigenous people, who live in several settlements very close to the type locality, as a vindication of their culture and history.

Distribution: Argentina: Northern Misiones Province: Reserva Natural de la Defensa Puerto Península: seasonal pond on the side of an internal road (coordinates 25°40'37.6104" S 54°34'42.402" W), Middle Paraná River basin. Elevation: 179 m a.s.l.; Coll.: F. Alonso, M. Montes, J. Casciotta, A. Almirón, P. Giorgis, L. Ciotek. October 2018.

Diagnosis: Argolebias guarani can be distinguished from all other conspecifics
by a unique color pattern that consists of the following: in adult living males, (1) scattered small dark brown to gray irregular spots on the laterodorsal surface of the head and anterior part of the trunk; (2) abundant and relatively large sub-square irregular iridescent turquoise, to pale blue spots on unpaired fins, evenly distributed, with those in the distal part elongated and confluent; (3) trunk and tail with anterocentral part of scales iridescent turquoise with gray edges forming a reticulated pattern; (4) thin outer edge
of scales in the dorsal part of the trunk, below the dorsal fin, iridescent
turquoise; and by (5) ventrolaterally directed anterior nostrils; and, in juveniles and young adults, (6) orange-yellow background coloration at base of unpaired fins and yellowish belly.

Further comparisons with species of Argolebias.

Argolebias guarani is similar and, based on our phylogenetic analysis, closely related to Argolebias nigripinnis and Argolebias paranaensis, sharing with Argolebias nigripinnis a unique character of preopercular and mandibular series of neuromasts separated (not evaluated in Argolebias paranaensis). This new species can be differentiated from Argolebias nigripinnis further by not presenting a bright iridescent subdistal stripe on the dorsal fin (vs. present) and by presenting an infraorbital bar narrower than the width of the orbit (vs. its dorsal portion approximately as wide as orbital diameter). It can be differentiated from Argolebias paranaensis by presenting the dorsal fin origin anterior to the anal fin origin (vs. posterior), more pectoral fin rays (12–13 vs. 10–11), shorter caudal fin length (22.9–28.1 vs. 34.5–35.3 in males; and 22.8–30.6 vs. 31.9–34.7 in females, in percentages of SL) and smaller eye diameter (27.2–31.6 vs. 34.8–38.4 in males; and 26.6–31.4 vs. 37.2–38.0 in females in percentages of HL). Also, Argolebias guarani can be differentiated further from Argolebias nigripinnis by the following: (1) presenting more pectoral fin rays (12–13 vs. 10–11); (2) a shorter caudal fin length (22.9–28.1 vs. 31.9–34.7 in males, and 22.8–30.6 vs. 31.9–34.7 in females, in percentages of SL); (3) a smaller eye diameter (27.2–31.6 vs. 32.8–37.1 in males, and 26.6–31.4 vs. 33.0–36.9 in females, in percentages of HL); (4) the presence of vertically elongated, dark grey blotches on the posterocentral portion of the trunk in females (vs. absent); (5) trunk and tail of mature males with anterocentral portion of scales iridescent turquoise with grey borders, generating a reticulated pattern (vs. black to grey general background with some scales with light blue anterocentral portion with grey borders arranged in irregular vertical lines); (6) a different colour pattern on the dorsal fin consisting of abundant, evenly distributed, relatively big and sub-square irregular iridescent turquoise to light blue blotches, with those in the distal portion elongated and merging (vs. fewer, smaller and rounded light blue blotches, mainly concentrated on the basal portion, and a subdistal light blue band); (7) dorsal portion between preopercle and opercle iridescent turquoise (vs. brownish); and (8) infraorbital bar thin and triangular (vs. wider, approximately same as eye width, and diffuse).

Coloration in life Males: Adult males present a markedly reticulated pattern on the body, with intense turquoise coloration. Scales on trunk, tail and dorsal portion of the head with dark grey borders. Anterocentral portion of most scales iridescent light blue to turquoise, except for those on the dorsal portion of the head and trunk, anterior to the dorsal fin origin, which present a grey central portion. The portion of the head posterior to the infraorbital band and ventral to the dorsal portion of the gill opening are light blue to turquoise. Small scattered irregular dark grey to brown blotches are present on the dorsal portion of the head. There is a dark brown blotch around the neuromast supraorbital series, posterior rostral series and orbital area. There is a short infraorbital band approximately as wide as the pupil. The pupil is black, horizontally elongated. There is a vertical black stripe on the eye, approximately the same width as the pupil. The iris is silver grey, with orange around the pupil. The ventral portion of the head and anterior abdominal region are light blue to whitish. The area over the dentary, maxilla and premaxilla is grey. The fins have a well-defined black border. With abundant, evenly distributed, relatively big and sub-square irregular iridescent turquoise to light blue blotches. Those in the distal portion are elongated and fused. The base of unpaired fins is orange in young individuals; grey with an orange hue in mature males. The first dorsal fin ray is dark black. The distal portion of dorsal fin rays is dark black, more marked on anterior rays, which can be completely black in some specimens. The pectoral fin is light grey, translucent, with a light blue to turquoise hue and light blue blotches on the medial distal portion, which, in some specimens, are scattered along the whole fin. Pelvic fins are dark grey with irregular light blue to turquoise blotches.

Coloration in life Females:

Females present a yellow to orange background coloration of the body and the basal portion of unpaired fins, which present light brown rays and a mainly hyaline interradial membrane. Anal and dorsal fins have light grey to light brown blotches, mainly concentrated on the basal portion and generally over the rays. Paired fins are hyaline. The caudal fin is hyaline. There are faint scattered irregular brown blotches on the trunk and tail. There are small, vertically elongated, dark grey blotches mainly concentrated on the central portion of the trunk. Thre is a small faint grey infraorbital band, thinner than the iris, which is light orange with a grey dorsal portion. The pupil is black. The ventral portion of the head and anterior ventral region are whitish. The opercle is light green, with scattered melanophores covering it. There is a dark brown blotch around the neuromast supraorbital series, posterior rostral series and orbital area. The area over the dentary, maxilla and premaxilla is grey.

The type locality is a seasonal pond, mainly covered with grass, in the Paraná Forest at ~185 m a.s.l., in an open space in the surrounding jungle, with abundant palm trees. The maximum depth measured was ~80  cm, and the water was clear. No submerged aquatic vegetation was observed. The bottom presented a soft sediment, with abundant organic matter.

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 by description;

The reproductive behaviour of this species in aquarium conditions appears to be like that described for other Austrolebias species (Belote 2004, García et al. 2008), as follows: (1) males present a lateral display in front of the females with deployment of unpaired fins and opening of the opercula; (2) males perform a lateral shaking of the body, pointing towards the substrate; (3) after the female pairs with the male, they burrow into the substrate; (4) the fish remain in the substrate for ~50 s, where the eggs are laid and fertilization occurs; and (5) afterwards, the fish emerge from the substrate (see Supporting Information, Appendix S10)

Max. size 00 mm in males - female smaller.
Dorsal (average, male only ) 00.0,
Anal (average, male only ) 00.0,
D/A (average, male only ) 0.0,
LL scale count (average) 00.0
Pre- dorsal length to SL – 00.0 %
Depth to SL – 00.0 %
Vertebrae count (average) 00.0