Austrolebias botocudo, Lanés & Volcan & Maltchik, 2021

Lanés, Luis Esteban Krause, Volcan, Matheus Vieira & Maltchik, Leonardo, 2021, Two new annual fishes (Cyprinodontiformes: Rivulidae) unexpectedly discovered in the highlands of southern Brazil, Zootaxa 4949 (3), pp. 499-520 : 501-506

Austrolebias botocudo , new species

( Figs. 1–2 , Table 1 )

Holotype. MCP 54450, male, 47.8 mm SL, Brazil, Rio Grande do Sul, Vacaria, temporary pool near rio Socorro, rio Apuaê-Inhandava drainage, upper rio Uruguay basin, 28°22’43.6” S, 50°52’21.8” W, altitude 934 meters a.s.l., L.E.K. Lanés & M. V. Volcan, 26 July 2017.

Paratypes. All from Brazil, Rio Grande do Sul, Vacaria, rio Socorro , rio Apuaê-Inhandava drainage, upper rio Uruguay basin : MCP 54450, male, 51.6 mm SL, same locality as holotype, L.E.K. Lanés , R.S. Godoy & V. Weber , 13 October 2016 ; MCP 54451, 2 males, 35.7–40.8 mm SL, collected with holotype ; MCP 54452, 3 males, 44.7–55.6 mm SL, 3 females, 28.5–39.3 mm SL, same locality as holotype, L.E.K. Lanés & M . V. Volcan , 26 Jul 2017 ; MCP 54453, 4 males, 36.5–54.6 mm SL (1 C&S), 6 females, 31.2–35.3 mm SL (1 C&S), 28°22’47.9” S, 50°52’ 07.9” W, altitude 926 meters a.s.l., L.E.K. Lanés , R. S. Godoy & M. Fogaça, 23 November 2013 ; MCP 54454, 3 males, 37.4–43.5 mm SL, 1 female, 33.2 mm SL, 28°22’47.9” S; 50°52’07.9” W, altitude 926 meters a.s.l, L.E.K. Lanés & R. S. Godoy & M. Fogaça, 30 Aug 2013 ; MCP 54455, 2 males, 28.0– 34.7 mm SL (1 C&S), 1 female, 25.6 (C&S), 28°22’47.9” S, 50°52’07.9” W, altitude 926 meters a.s.l., L.E.K. Lanés & A.B. Moraes, 10 May 2013 ; MCP 54456, 1 male, 34.8 mm SL (C&S), 1 female, 31.8 (C&S) 28° 22’43.6” S, 50°52’21.8” W, altitude 934 meters a.s.l., L.E.K. Lanés & A.B. Moraes, 10 May 2013 .

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 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).

Description. Morphometric data are presented in Table 1 . Largest male examined 55.6 mm SL; largest female examined 39.3 mm SL. Dorsal profile slightly concave on head, convex from nape to the end of dorsal-fin base, nearly straight on caudal peduncle. Ventral profile convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body moderately deep and compressed. Greatest body depth at vertical of pelvic fin origin. Lower jaw relatively long and prognathous, snout blunt.

Dorsal-fin rays in males 22–24; in females 18–20. Dorsal fin sub-rectangular in males, with posterior tip rounded. Dorsal fin semi-circular in females. Origin of dorsal fin in males at vertical through neural spine of 7–9th vertebrae; in females through 10–11th vertebrae. Anal-fin rays in males 21–23, in females 18–20. Anal-fin sub-rectangular, with tip rounded in males. Anal-fin sub-triangular in females. Anteromedian rays of anal fin lengthened in females. Anal-fin origin at vertical through base of 3–5th dorsal-fin ray in males and through base of 2–4th dorsal-fin ray in females, and at vertical through pleural ribs of 8–9th vertebrae in males; and through 10–12th vertebrae in females. Caudal fin distal margin rounded, 24–27 rays in both sexes. Caudal-fin rays supported by last 4 vertebrae. Pectoral fin rays 12–14 in both sexes; pectoral-fin margin rounded. Pectoral-fin posterior tip reaching from before pelvic fin origin to 2nd anal-fin ray in males, from origin of pelvic fin or before it in females. Pelvic fins usually well-developed, with 5–6 rays, its tip extending from urogenital papilla to 2nd anal-fin ray in males, and to urogenital papilla in females. Urogenital papilla not attached to anal fin. Pelvic-fin bases medially separated by short interspace.

Scales large and cycloid. Head and trunk entirely scaled, except ventral surface of head. Frontal squamation F, G, or H, sometimes irregularly arranged. No scales on dorsal and anal fin bases. Longitudinal series of scales 27–30, scales regularly arranged; transverse series of scales 11–16; 18–22 scale rows around caudal peduncle. Few, scattered contact organs on scales throughout body in males, when present located mainly at mid-ventral region of the flank from immediately distal tip of opercle to caudal peduncle. Usually one contact organ per scale of longitudinal series; rarely two contact organs along some scales of longitudinal series (present in only three males). Contact organs on distal portion of anteriormost 1–4 anal fin rays, present in 25% of males. Contact organs on outer region of 1–4 uppermost pectoral fin rays in males.

Cephalic neuromasts: supraorbital 14–23, parietal 1–3, anterior rostral 1–2, posterior rostral 1, infraorbital 2–3+22–27, preorbital 2–3, otic 2–4, post-otic 2–5, supratemporal 1–2, median opercular 1, ventral opercular 2–4, preopercular + mandibular 36–43, lateral mandibular 5–9, paramandibular 1. Two neuromasts on caudal fin base.

Six branchiostegal rays. Dermosphenotic ossification absent. Urohyal deep. Total number of vertebrae 28–29. Gill rakers in first branchial arch 3+8–9. Basihyal subtriangular, width about 60–75% of length; basihyal cartilage about 40–50% of total basihyal length. One to three teeth on second pharyngobranchial. Vomerine teeth absent.

Colouration in life. Males ( Fig. 2A–D ). Ground colour of body lilac grey, brown in dorsal region, with 7–12 bluish white vertical bands, usually with narrower, overlapping or poorly defined stripes between well-defined bars. Some specimens in a dominant situation shown a darker coloured pattern, composed of a blue-purple background with vertical grey-green stripes. Pectoral and ventral region greyish. Melanophores irregularly distributed over the body, forming black dots, spots or irregular marks. Some specimens exhibit a concentration of melanophores in the middle of the flank, forming irregular black vertical bands. This pattern is more frequent in senile individuals. Opercle and preopercle greenish blue. Supraorbital and suborbital bars black. Pectoral fin hyaline, margin black. Pelvic fins dark blue or dark grey. Iris orange; dark vertical band crossing the eye. Dorsal fin dark blue with light grey elongated dots. Anal fin bluish-green with light, elongated grey dots; distal margin of anal fin darker. Caudal fin bluish grey with light grey dots and spots, distal margin hyaline.

Females ( Fig. 2E–H ). Ground colour of body pale yellowish brown, generally with brown, dark brown or black spots distributed over the flank. Some individuals presenting a spotted pattern with several circular marks, which extends from dorsum to the medium flank. Dorsum generally pale yellowish brown. Some specimens present black melanophores in the dorsal region. Venter light yellowish grey. Sides of head yellowish brown, opercular region pale golden or bluish golden. Suborbital bar grey. Iris light yellow with transverse grey bar through centre of eye. Unpaired fins yellowish hyaline, with sparse and little conspicuous grey dots. Pectoral fin hyaline. Pelvic fin hyaline.

Distribution. The species was recorded only in two temporary pools located in a highland grassland landscape at the rio Socorro, a tributary of upper rio Apuaê-Inhandava (upper rio Uruguay basin), in altitudes between 926 and 934 meters a.s.l., Vacaria municipality, Rio Grande do Sul State, southern Brazil ( Fig. 3 ).

Etymology. The specific epithet “botocudo” is a reference to an indigenous people, which formerly inhabited the region and belonged to the Xokleng Laklãnõ ethnic group, known during the 19th century as “Botocudos”, because adult men used a botoque (a plug-like wooden disk) to enlarge the lower lip. An allusion to a feature presented by the species, where the lower jaw seems more prominent than other species belonging to the subgenus Acrolebias .

Ecological notes. Austrolebias botocudo was found only in two isolated high-altitude temporary wetlands, located within a private farmland, with size areas of 2,500 and 13,000 m 2. These two biotopes present clear (sometimes turbid), still water, with a latosol soil type, and are located in a grassland landscape ( Fig. 4 ). The wetlands are close to each other (less than one kilometer apart) but are hydrologically isolated. A portion of the larger temporary pool was excavated, probably to become a water source for cattle. There are small intermittent drainages associated with the pools. The vegetation is composed mainly by stands of Peruvian watergrass ( Luziola peruviana ), peatbog ( Sphagnum sp.), and other emergent, floating and submerse macrophytes. During winter and early spring, when the temporary pools present water, the minimum air temperature reaches 0°C (often negative temperatures are recorded), and frost, dew, fog and even snow can occur. The area where the biotopes inhabited by A. botucudo lie within are used for extensive cattle ranching. In the surroundings, mainly soybean crops and orchards (apples and pears) have drastically altered the natural high-altitude grasslands landscape.

Conservation. In accordance with IUCN criteria, Austrolebias botocudo should be considered as “Critically Endangered”, with the criteria CR B2ab (ii, iii). The species presents an area of occupancy of 15,500 m 2 (AOO less than 10 km ²), present severely fragmented populations (a) with continued decline (b) in area of occupancy (ii) and quality of habitat (iii).

Figures

FIGURE 1. (A) Austrolebias botocudo, MCP 54452, holotype, male, 47.8 mm SL; (B) Austrolebias botocudo, MCP 54452, paratype, female, 39.3 mm SL (after preservation) from rio Socorro, rio Upuaê-Inhandava, upper rio Uruguay basin, Vacaria, Rio Grande do Sul, Brazil. Photo by Luis Esteban Krause Lanés.

FIGURE 2. Austrolebias botocudo living colouration (non-preserved specimens) from rio Socorro, rio Upuaê-Inhandava, upper rio Uruguay basin, Vacaria, Rio Grande do Sul, Brazil. Males (A–D), females (E–H). Photos by Matheus Volcan (Fig. 2A, C, D, E, and F) and Pedro Hoffmann (Fig. 2B, G, and H).

FIGURE 3. Map of southern Brazil indicating the known distribution of members of the subgenus Acrolebias: Red star: Austrolebias botocudo; yellow star: A. nubium; white circle: Austrolebias araucarianus; black circle: Austrolebias carvalhoi.

FIGURE 4. Biotopes of Austrolebias botocudo from the upper rio Socorro, a tributary of the upper rio Apuaê-Inhandava drainage, upper rio Uruguay basin, Rio Grande do Sul, Brazil. (A) Panoramic view from the type-locality; (B) Type-locality during flood season; (C) Type-locality drying; (D) Temporary pool after an intense cold period with occurrence of frost and snow. (E) Same temporary pool with recovered vegetation condition. Photos by Luis Esteban Krause Lanés.