IUCN threat status:

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Comprehensive Description

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Austrolebias paranaensis , new species

(Fig. 28)

Material examined

Holotype . UFRJ 6239 , male, 25.4 mm SL; Paraguay : Misiones : temporary pools adjacent to rioParana , about 2 km E of Ayolas , 27°24’0”S56º46’12”W ; J. N. Taylor & G. R. Smith , 26 Aug. 1979 .

Paratypes . Paraguay : Misiones : UFRJ 4975 , 7 males, 15.7-19.7 mm SL, 4 females, 16.3-25.0 mm SL; UFRJ 4974 , 1 male, 25.1 mm SL, 2 females, 21.0-21.9 mm SL (c&s); all collected with holotype .

Diagnosis

Distinguished from all other congeners except A. nigripinnis by possession of a wide infraorbital bar, its dorsal portion approximately so wide as orbital diameter (vs. conspicuously narrower than orbit). Differs from A. nigripinnis in having dorsal-fin origin posterior to anal-fin origin (vs. anterior) and a wide, nearly triangular basihyal, its width about 50 % basihyal length (vs. nearly rectangular, width about 35 % basihyal length).

Description

Morphometric data appear in Table 4. Males larger than females, largest male examined 25.4 mm SL, largest female 25.0 mm SL. Dorsal profile nearly straight to slightly concave on head, convex from nape to end of dorsal-fin base, approximately straight on caudal peduncle; small adipose ridge on frontal region of head in males. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Greatest body depth at level of pelvic-fin base. Body moderately slender and compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fins rounded. Anteromedian rays of anal fin of females not lengthened; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins rounded, posterior margin on vertical between base of 6th and 8th anal-fin rays in males, between urogenital papilla and anal-fin origin in females. Tip of each pelvic fin reaching between base of 3rd and 5th anal-fin rays in males, between base of 1st and 3rd anal-fin rays in females. Pelvic-fin bases united, sometimes medial margin about 40 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 1st and 2nd anal-fin rays; dorsal-fin origin between neural spines of 6th and 7th vertebrae in males, between neural spines of 9th and 11th vertebrae in females. Anal-fin origin between pleural ribs of 6th and 7th vertebrae in males, between pleural ribs of 8th and 10th vertebrae in females. Dorsal-fin rays 23-25 in males, 18-20 in females; anal-fin rays 22-24 in males, 20 in females; caudal-fin rays 22-24; pectoral-fin rays 10-11; pelvicfin rays 5-6.

Scales large and cycloid. Trunk and head entirely scaled, except on ventral surface of head. No scales on dorsal and anal-fin bases, and two rows of scales on caudal-fin base. Frontal squamation usually H, sometimes G or F-patterned; E-scales overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 25-27, scales regularly arranged; transverse series of scales 13; scale rows around caudal peduncle 16. One contact organ on each scale of ventral portion of flank and opercle in males. Row of minute contact organs on two uppermost pectoral-fin rays in males; no contact organs on unpaired fins.

Cephalic neuromasts: supraorbital 16-18, parietal 1-2, anterior rostral 1, posterior rostral 1, infraorbital 2 + 23, preorbital 3, otic 2, post-otic 2-4, supratemporal 1, median opercular 1, ventral opercular 3, preopercular 19, mandibular 9-10, lateral mandibular 5.

Basihyal subtriangular, width about 50 % of length; basihyal cartilage moderate in length, about 30-40 % of total basihyal length, without lateral projections. Six branchiostegal rays. Three teeth on second pharyngobranchial. Gill-rakers on first branchial arch 2 + 8. Dermosphenotic ossification absent. Ventral process of posttemporal vestigial. Total vertebrae 26-28.

Coloration (life colors unknown, description based only on preserved material)

Males: sides of body dark brown, with vestiges of about 8 vertical rows of light brown dots arranged in zigzag pattern; juveniles with 7-8 light brown bars. Opercular and infraorbital regions brown; melanophores concentrated on infraorbital region forming wide bar, about same width as orbit, and slightly concentrated on posterior portion of supraorbital area adjacent to orbit. Unpaired fins dark brown. Pectoral and pelvic fin dark gray.

Females: sides of body light yellowish brown, with small, coalesced dark gray spots; no black spots on anterocentral portion of flank and caudal peduncle. Opercular region light brown; infraorbital and supraorbital marks as in males. Unpaired fins hyaline, with small dark brown spots; paired fins hyaline.

Distribution

Known only from the type locality, ríoParaná floodplains, southern Paraguay (Fig. 20).

FIGURE 28. Austrolebias paranaensis , UFRJ 6239, male holotype, 25.4 mm SL, above, UFRJ 4975, female paratype, 25.0 mm SL, below; Paraguay: Misiones: Ayolas.

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Source: Plazi.org

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