Reproductive biology and egg production of Hyalella longistila (Faxon, 1876) (Amphipoda: Hyalellidae), a freshwater amphipod in southeastern Brazil

Abstract

The reproductive biology of Hyalella longistila (Faxon, 1876), a freshwater amphipod found in streams in southeastern Brazil, was investigated. We assessed body-size relationships between paired and unpaired males and females as well as the egg stage, fecundity, relationship between number of eggs and their stage, number of eggs and female size, and pairing and reproductive success. A positive Spearman rank correlation was observed between the cephalothorax length (CL) of paired males and females. The mean CL of paired males and females was positively related, indicating a size-assortative mating. The mean fecundity was 12.88 ± 2.00 eggs per female, with peaks in August 2012 and September 2012, with 16.82 and 15.08 eggs per female, respectively. The developmental stage and the number of eggs found on the brood pouch were negatively correlated, indicating that as the embryo developed, fewer eggs remained in the egg pouch (marsupium). Higher values for male pairing success were observed for size classes between 0.59 and 0.67 mm, and both sexes presented higher values for reproductive success between 0.63 and 0.68 mm. Our results could support conservation practices or even studies using such amphipods as model organisms.