Life cycle of the freshwater anomuran Aegla schmitti Hobbs, 1978 (Decapoda: Anomura: Aeglidae) from southeastern Brazil

Abstract

We describe the reproductive cycle, population structure, growth and longevity of Aegla schmitti Hobbs, 1978 from the Betari River, at the Alto Ribeira Tourist State Park (24°31′57″S, 48°42′09″W), on the southern portion of state of Sao Paulo. A total of 1528 specimens (1204 males and 324 females) were sampled from September 2010 to December 2011. Carapace length excluding rostrum (CL) was measured in all individuals, and females were inspected for late developing ovaries or eggs attached to the pleopods. Growth curve equations were CL t = 28 . 358 ( 1 − e − 0 . 058 ( t + 1 . 127 ) ) for males and CL t = 21 . 69 ( 1 − e − 0 . 060 ( t + 1 . 468 ) ) for females. Average longevity was estimated to be 34.03 and 38.40 months for males and females, respectively. Size at the onset of functional maturity of females was estimated as 12.92 mm of CL. Aegla schmitti from the Betari River has two reproductive cycles during the expected lifespan. Each reproductive cycle extends for 9 months and can be subdivided in two sequential periods of similar duration: a first, from April to July, characterized by higher reproductive intensity and including the hatching of most of the juveniles in July, and a second, from August to December, with less intense reproductive activity. We discuss regional variations in water flow velocity as a selective pressure that regulates the timing of juvenile hatching in Aegla schmitti as well as in other aeglid species.