Life history of Karualona muelleri (Richard, 1897) (Chydoridae, Aloninae)

Abstract

Many taxonomic issues still need to be solved for the family Chydoridae, but mainly in the subfamily Aloninae. The species Karualona muelleri is an example of a recent taxonomic redefinition, since it was decoupled from the genus Alona and translocated to another genus. In order to expand our knowledge on the species, we investigated population growth and compared the morphometry of the first and second instars, male, parthenogenetic female, ephippial female, and ephippium. An experimental population was obtained by hatching resting eggs collected from the sediment in a temporary lake located in the Serra da Canastra National Park (Minas Gerais, Brazil). The hatched individuals were subjected to morphometric analyses and used in experiments to assess population growth and fecundity. Reproductive age and lifespan were also monitored in two groups of females in different life stages: parthenogenetic and gamogenetic. The reproductive age occurred between the 1st and 15th days of life, and the greatest longevity was 17 days. The start of gamogenetic reproduction was stimulated by elevated population densities and it characterized the slowdown of exponential population growth. Morphometric analyses detected differences between the development phases, as well as similarities in the morphological features of the male, first and second instars, and the two types of females.