Ecdysteroids in the pycnogonid Pycnogonum litorale (STROM) (Arthropoda, Pantopoda)

Two ecdysteroids were isolated from juveniles and adults as well as from eggs of the pycnogonid Pycnogonum litorale Ström and characterized by bioassay, thin layer chromatography, gas liquid chromatography, and high performance liquid chromatography. One of the hormones could be identified as 20-hydroxyecdysone whereas the other behaves in HPLC in a way that is similar to but not identical with ecdysone. This unidentified ecdysone-like hormone exceeded 20-hydroxyecdysone in all developmental stages (1.67:1 to 3:1). Determination of moulting hormone titers by a radioimmunoassay showed highest amounts of hormones in juvenile females (150 ng/mg tissue dry wt). The results are compared with those obtained from other arthropods and are discussed in view of the evolution of hormonal systems.