Austrolebias paucisquama, Ferrer & Malabarba & Costa, 2008

Ferrer, Juliano, Malabarba, Luiz R. & Costa, Wilson J. E. M., 2008, Austrolebias paucisquama (Cyprinodontiformes: Rivulidae), a new species of annual killifish from southern Brazil, Neotropical Ichthyology 6 (2), pp. 175-180: 176-179

publication ID

http://doi.org/ 10.1590/S1679-62252008000200004

DOI

http://doi.org/10.5281/zenodo.5072586

persistent identifier

http://treatment.plazi.org/id/96378445-3430-FFB5-FF34-F9C069D0FAD0

treatment provided by

Carolina

scientific name

Austrolebias paucisquama
status

new species

Austrolebias paucisquama   , new species Figs. 1 - 3 View Fig View Fig View Fig

Holotype. MCP 41879 View Materials , male, 34.2 mm SL, Brazil, Rio Grande do Sul, São Sepé, temporary pool close to BR-290 highway (30°22’27”S 53°33’42”W), rio Vacacaí drainage, rio Jacuí tributary, 15 Sep 2004, J. Anza, J. Giora & A. Pereira. GoogleMaps  

Paratypes. Brazil: Rio Grande do Sul: UFRJ 6522, 5 males (1 c&s), 25.2-27.7 mm SL, 5 females (1 c&s), 25.6-34.0 mm SL   ; MCP 41880 View Materials , 12 males (2 c&s), 22.4-31.7 mm SL, 14 females (1 c&s), 18.8-34.8 mm SL; and   UFRGS 9354 View Materials , 3 males (3 c&s), 22.1-24.9 mm SL, collected with the holotype   . UFRGS 9355 View Materials , 6 males, 21.0- 28.5 mm SL, 1 female, 21.4 mm SL, same locality of the holotype, 9 Jun 2005, J. Ferrer, J. Giora, R. Hirano & D. Rocha   .

Diagnosis. The dark gray pectoral fins combined with the bright blue iridescence in males distinguishes A. paucisquama   from other species of the genus Austrolebias   , except from those of the A. alexandri   species-group. The fewer scales around caudal peduncle (12 vs. 16 or more) and the fewer dorsal-fin rays in males (17-21 vs. 20 or more in A. litzi   and A. nigripinnis   ; 21 or more in A. affinis   , A. alexandri   , A. cyaneus   , A. juanlangi   and A. luzardoi   ; 22 or more in A. duraznensis   , A. ibicuiensis   , A. paranaensis   , A. periodicus   ) distinguish A. paucisquama   from other species of the A. alexandri   speciesgroup. The lack of contact organs on the inner surface of the pectoral fin in males and the color pattern of females – ground color light brownish, sides of body with a variable number of relatively large dark black spots distributed mostly on posterior portion of body – distinguish A. paucisquama   from all other species of the genus.

Description. Morphometric data on Table 1 View Table 1 . Largest male 34.2 mm SL; largest female 34.8 mm SL. Body compressed. Dorsal head profile slightly concave, more evident in females. Dorsal profile convex from nape to insertion of last dorsal-fin ray. Ventral profile concave from lower jaw to last anal-fin ray insertion. Dorsal and ventral profiles of caudal peduncle nearly straight. Maximum body width at least 2.21 in maximum body depth. Greatest body depth at pelvic-fin insertion. Snout blunt. Jaws short.

Dorsal and anal fins rounded. Anterior anal-fin rays in females prolonged forming anterior lobe; in males all anal-fin rays with approximately same length and not forming lobes. Anal-fin origin just posterior or just anterior to dorsal-fin origin in males; posterior to dorsal-fin origin, at vertical through base of second to fourth dorsal-fin rays in females. Base of dorsal-fin origin at vertical between 8th and 9th pleural ribs in males and between 11th and 12th pleural ribs in females. Base of anal-fin origin at vertical between 8th and 9th pleural ribs in males and between 12th and 13th pleural ribs in females. Urogenital papilla not attached to anal fin. Caudal fin rounded. Pectoral fins elliptical, posterior margin on vertical between urogenital papilla and base of 2nd anal-fin ray in males, reaching or almost reaching pelvic-fin base in females. Tip of each pelvic fin reaching base of 2 nd or 3 rd anal-fin rays in males, between urogenital papilla and base of 1st anal-fin ray in females. Pelvic-fin bases in close proximity, medial membrane not united. Dorsal-fin rays 17-21 in males and 15-21 in females.Anal-fin rays 19-23 in males and 17-19 in females. Caudal-fin rays 23-27, usually 25. Pectoral-fin rays 11, rarely 12. Pelvic-fin rays 4-5.

Scales large and cycloid. Trunk and head scaled, except ventral surface of head. No scales on dorsal and anal-fin bases, and two rows of scales on caudal-fin base. Frontal squamation H-patterned. Longitudinal series of scales 25-26, regularly arranged; transversal series of scales 11-13; scale rows around caudal peduncle 12. Minute contact organ on each scale of anteroventral portion of flank in males. No contact organs on fins.

Cephalic neuromasts: supraorbital 15-21, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 24-28, preorbital 2, otic 1-2, post-otic 1-3, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 19-22, mandibular 8-11, lateral mandibular 4-6. Six branchiostegal rays. Gill-rakers on first branchial arch 2+8. Total vertebrae 28-30.

Life coloration in males. Ground color dark gray. Sides of body with 6, 7 or rarely 8 iridescent greenish-blue vertical bars, two or three times narrower than space between each pair of bars, and not extended to dorsum. Urogenital papilla gray. Opercular and infraorbital regions greenish-blue, with vertical and near rectangular dark bar below eye and small dark grayish triangular spot dorsoposterior to eye not reaching parietal neuromasts. Iris white anteriorly and posteriorly; red and black pigmented vertical bar crossing center of eye. Dorsal and anal fins iridescent greenish-blue, sometimes with light spots; usually grayish near fins base. Caudal fin iridescent greenish-blue, except at distal portion. Pelvic and pectoral fins bright iridescent blue. Distal border of dorsal, anal, pectoral and pelvic fins black pigmented ( Fig. 1 View Fig ).

Color in males just after fixation in formalin. Color pattern of bars and spots basically same in life and just fixed specimens. General body color, however, changes drastically. Red pigments do not change, but iridescent greenish-blue pigments become very intense blue, giving general dark blue appearance to fish ( Fig. 2 View Fig ).

Life coloration in females. Ground color light brownish. Sides of body with variable number of relatively large dark black spots, distributed mostly on posterior portion of body. Purple line discernible approximately on distal border of hypural fan. Belly golden in all observed females. Urogenital papilla light. Opercular region, and sometimes infraorbital region bright green, with vertical and narrow dark bar below eye. Iris white anteriorly and posteriorly, and black pigmented below and above the pupil. All fins hyaline ( Fig. 3 View Fig ).

Distribution. Known only from the type-locality, a temporary pool in the rio Vacacaí drainage, rio Jacuí tributary, laguna dos Patos drainage ( Fig. 4 View Fig ).

Habitat. The type locality consists of a small temporary pool located close to the BR290 highway, and distant from any permanent freshwater flow in the altitude of 154 m ( Fig. 5 View Fig ). The specimens of Austrolebias paucisquama   were the only group, by sharing the apomorphic bright blue iridescence and pectoral fins dark gray in males. However, A. paucisquama   is easily distinguished from all species of the genus by the lack of contact organs in the pectoral fins of males, the reduced number of scales around caudal peduncle, the reduced number of dorsal-fin rays in males and the color pattern of females.

Most Austrolebias   species inhabit lowlands and inundated areas adjacent to permanent waters, in altitudes usually lower than 150 m ( Costa et al., 2004). These species seem to have larger areas of distribution (e.g. A. alexandri   , A. elongatus   , A. gymnoventris   , A. luteoflammulatus   , A. monstrosus   , A. prognathus   , A. vazferrerae   , A. wolterstorffi   , see Costa, 2006). So far A. paucisquama   has been recorded only from a temporary pool, without the proximity of a permanent water flow, in the altitude of 154 m and close to an area of extensive use as pasture. This situation places the new species as a critically endangered species of Austrolebias   .

fishes collected in two collecting efforts in September 2004 and June 2005, corresponding to winter and autumn in the southern hemisphere. Maximum depth observed was 50 cm. The environment was almost completely covered with emergent vegetation, serving as cattle pasture.

Etymology. From the Latin “ pauci ” meaning few, and “ squama ” meaning scales, in reference to the reduced number of scales around caudal peduncle. A name in apposition.

MCP

Pontificia Universidade Catolica do Rio Grande do Sul