Hypsolebias tocantinensis, Nielsen, Dalton Tavares Bressane, Cruz, João Carlos & Junior, Arsênio Caldeira Baptista, 2012

Nielsen, Dalton Tavares Bressane, Cruz, João Carlos & Junior, Arsênio Caldeira Baptista, 2012, A new species of annual fish, Hypsolebias tocantinensis sp. n. (Cyprinodontiformes: Rivulidae) from the rio Tocantins basin, northeastern Brazil, Zootaxa 3527, pp. 63-71 : 64-68

Hypsolebias tocantinensis , new species

( Figs.1 and 2 ; Table 1 ).

Holotype. Deposited at Universidade de Campinas, Campinas, São Paulo, Brazil. ( ZUEC 7019) male 38.2mm SL: Brazil, Maranhão, Campestre do Maranhão, temporary pool near rio Lajeado, rio Tocantins basin, 06º-05'-12.43”S, 047º-22'-54.01” W, altitude 133m, 0 1 April 2011. Col. Arsênio Caldeira Baptista Junior and João Carlos da Cruz.

Paratypes. Deposited at Universidade de Campinas, Campinas, São Paulo, Brazil. ( ZUEC 7020), 1 male (37.4mm SL), 7 females (27.7–31.1mm SL), collected with the holotype.

Diagnosis. Hypsolebias tocantinensis differs from the remaining species of the H. flammeus species-group, except from H. multiradiatus , H. flammeus (Fig.3), and H.brunoi (Fig.4), by the male body color pattern, with reddish brown bars alternating in a bright blue background, by the male’s anal fin being bright blue (vs. pale yellow or brownish red), and by the presence of a metallic blue sheen surrounding the female’s black spots (vs. absence of such a pattern). Hypsolebias tocantinensis differs from all other Hypsolebias by the presence of short extensions in male dorsal and anal fin rays, starting at the 15th ray in the dorsal fin and 7th ray in the anal fin (vs. no ray extensions or long extensions in all rays). Hypsolebias tocantinensis is unique among the Cynolebiasini by having irregular light brown markings on the female anal fin. Additionally, H. tocantinensis differs from H. flammeus , H. multiradiatus and H. brunoi by the angle of the reddish brown bars on the body of the male. Whereas H. flammeus H. multiradiatus and H. brunoi have vertical bars, in H. tocantinensis the bars are slightly diagonal, approximately 15° from vertical.

Description. Morphometric data presented in Table 1 . Largest specimen examined 38.25mm SL. Body relatively deep, compressed, greatest body depth at level of pelvic fin base. Snout blunt. Urogenital papilla cylindrical and very short in males, pocket-shaped in females. Dorsal profile convex from snout to end of dorsal fin base, slightly concave or straight on caudal peduncle. Ventral profile convex from lower jaw to the end of anal fin base, nearly straight on caudal peduncle. Eyes positioned on upper portion of side of head.

Tip of dorsal and anal fin rounded in males and females. Short filamentous ray extensions from 15th ray on dorsal fin and 7th ray on anal fin in males; filaments absent in females.

Dorsal and anal fin unbranched in males and females. Caudal fin rounded. Pectoral fin elliptical. Posterior margin of each pectoral fin reaching vertical through base of fifth or sixth anal-fin ray in males, and between pelvic fin and urogenital papilla in females. Tip of each pelvic fin reaching base of first anal-fin ray in males and females. Pelvic fin bases close to each other. Dorsal-fin origin between origins of pelvic- and anal-fins in males; anal-fin origin on vertical through base of fourth dorsal-fin ray. Dorsal-fin origin posterior to anal-fin origin in females, on vertical through base of third anal fin ray. Dorsal fin origin between neural spines of vertebrae 6 and 7 in males, and neural spines of vertebrae 10 and 11 in females. Anal fin origin at 7th pleural ribs of vertebrae in males, and pleural ribs of vertebrae 9 in females. Dorsal-fin rays 19–20 in males, 13–15 in females, anal-fin rays 21–22 in males, 17–19 in females, caudal-fin rays 21–26, pectoral-fin rays 12–14,pelvic-fin rays 5.

Frontal squamation E-patterned; E-scales overlapping medially; no row of scales anterior to H-scale; supraorbital scales 2. Longitudinal series of scales 24–25; transverse series of scales 11–13; scale rows around caudal peduncle 12–13. Small papillae contact organ only on inner surface of three dorsal-most rays of pectoral fins in males, absent in scale of flank and ventral portion of opercular area. Total vertebrae 26–27.

Coloration in life ( Figs. 1–2 ). Males. Diagonally positioned 8–9, reddish brown bars alternating with a bright blue background. Head with dorsal and pre-dorsal areas light red. Opercular area greenish with a metallic blue tinge. Black transversal stripe crossing eyes vertically, iris light yellow. Dorsal fin with irregularly branching, reddish brown bars alternating with light blue blotches and spots. Caudal fin light blue with 4–5 reddish brown bars, with the first two bars irregularly branched. Anal fin with 5 reddish brown bars, in-line with bars on body, alternating with light blue stripes. Pectoral fins hyaline. Pelvic fins reddish brown. Females. Body sides light gray, with faint gray bars between the black spot and caudal fin. One or two black elliptical spots surrounded by metallic blue color, golden on ventral area. Opercular region light metallic green. Iris light yellow, with dark gray stripe through center of eye. Dorsal fins hyaline, anal fin hyaline with irregular reddish brown markings. Pectoral, pelvic and caudal fins hyaline.

FGURE 3. Hypsolebias flammeus from temporary pool close to rio Paranã, Brazil, Goiás (14º02'14.21"S 46º50'57.85"W), rio Tocantins basin.

Distribution ( Fig.5 ). Known only from the type-locality, a flooded area close to the rio Lajeado, rio Tocantins basin, Maranhão state, Brazil.

Habitat ( Fig.6 ). The temporary pool is located in a flooded area about 200 m from the rio Lajeado, in Campestre do Maranhão. The pool has been altered from its original state as it was cut in half by an interstate highway (Belém-Brasília, BR-010).Average depth of the pool is 1m, with deepest portions about 1.5m, with as lightly acid pH (6.4) and low electric conductivity (0,05µs). The substrate is composed of clay and sand with slightly dark water. The temperature on the water surface was approximately 27ºC and, in the deepest portion and banks, approximately 21ºC. The region’s annual average temperature is 26ºC, with maximum of 38.2ºC and minimum of 20.6ºC. The region has an annual average rainfall of 1400mm per year, with a rainy season from November to March. Marginal vegetation is composed primarily of grass for cattle pasture (altered from Amazonian Rain Forest).Aquatic vegetation is composed essentially of grass tufts, Echinodorus sp. and Nynphea sp. At the same locality two other rivulids were also found, Pituna compacta and Plesiolebias filamentosus , with Hypsolebias tocantinensis being the least abundant. This locality demonstrates the amazing ability annual fish have to survive in adverse conditions; even with the habitat being cut by a major road and having its vegetation completely altered, the pool was sustaining a very healthy population of fishes, with very large number of Pituna compacta and Plesiolebias filamentosus . The lower occurrence of H. tocantinens is in this locality might be related to the pool’s cycle, as the collection was done at the beginning of the dry season and the water level was already receding. Individuals of Hypsolebias spp. present an accelerated metabolism and normally start dying even before the pool dries out. The accelerated metabolism is even more accentuated in males, which can be observed in several other locations where Hypsolebias and Cynolebias occur ( Nielsen, 2008).

FGURE 4. Hypsolebias brunoi from a temporary pool close to ribeirão Canabrava, Brazil, Goiás, near the city of Vila Boa(15º03’0.4”S 47º04’3.3”W), rio Tocantins basin.

Behavior in captivity. Specimens of the new species demonstrated to be very pacific and not too prolific. Agonistic behavior was not observed among males, females or between males and females. No fighting was ever observed, with all specimens maintaining their fins intact for the duration of the observation period. Etymology. The name tocantinensis is in reference to the occurrence of the new species in the rio Tocantins basin.

Figures

FIGURE 1. Hypsolebias tocantinensis, male, holotype, 38.2 mm SL: Brazil, Maranhão, flooded areas close to rioLajeado. rio Tocantins basin.

FIGURE 2. Hypsolebias tocantinensis, female, paratype, 31.1 mm SL: Brazil, Maranhão, flooded areas close to rioLajeado. rio Tocantins basin.

FIGURE 5. Geographic distribution of members Hypsolebias from rio Tocantins basin.

FIGURE 6. Type locality of Hypsolebias tocantinensis near rio Lajeado, rio Tocantins basin.

Tables

TABLE 1. Morphometric and Meristic data for the holotype (H) and paratypes of Hypsolebias tocantinensis.

	H	Paratypes
	Male	Male n=1 Females n=7
Standard length (mm) Percents of standard length	38.2	37.4 27.7–31.2
Body depth	35.3	30.5 25.9–29.9
Caudal peduncle depth	13.0	11.7 10.5–12.2
Pre-dorsal length	44.7	42.7 53.9–60.4
Pre-pelvic length	43.0	39.3 45.8–49.9
Length of dorsal-fin base	38.5	35.3 21.2–24.2
Length of anal-fin base	34.8	35.3 21.8–25.6
Caudal-fin length	28.1	26.7 25.2–28.8
Pectoral-fin length	21.5	24.2 19.2–21.8
Pelvic-fin length	8.3	9.6 8.8–10.8
Head length	29.4	28.3 25.6–29.1
Percents of head length
Head depth	84.4	92.4 90.1–94.9
Head width	63.2	61.6 60.0–68.2
Snout length	11.9	11.2 11.2–14.1
Lower jaw length	18.1	16.0 15.0–18.7
Eye diameter	27.9	23.6 30.5–33.1
Counts
Dorsal fin	20	19 13–15
Caudal fin	21	26 21–23
Anal fin	22	21 17–19
Pelvic fin	6	6 6
Pectoral fin	14	14 12–13
Meristic
Scales in longitudinal series	25	25 24–25
Scales in transversal series	13	12 11
Horizontal scales around caudal peduncle	13	12 13