Austrolebias periodicus (Costa, 1999)
photo by Volcan, M.V.

Family:  Rivulidae (Rivulines), subfamily: Cynolebiinae
Max. size:  5 cm TL (male/unsexed)
Environment:  benthopelagic; freshwater, non-migratory
Distribution:  South America: IbicuĆ­ and QuaraĆ­ (= Cuareim) river drainages, rio Uruguay basin in southern Brazil and northwestern Uruguay.
Diagnosis:  Dorsal soft rays (total): 16-26; Anal soft rays: 17-25; Vertebrae: 27-29. Can be diagnosed from other species of the Austrolebias alexandri group by the following combination of characters: posterior margin of each pectoral fin in male reaching a vertical between base of second and fifth anal-fin rays (vs. between urogenital papilla and base of second anal-fin ray); origin of dorsal fin either on vertical through anal-fin origin or posterior to it (vs. anterior); and presence of vertical rows of light blue dots on entire flank in larger males (vs. light blue bars) (Ref. 57613). Description: Dorsal-fin rays 22- 26 in males, 16-18 in females; anal-fin rays 21-25 in males, 17-23 in females. Longitudinal series of scales 26-28; and transverse series of scales 10-12; (Ref. 57613).
Biology: 
IUCN Red List Status: Not Evaluated (N.E.) Ref. (130435)
Threat to humans:  harmless


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