Abstract
The embryonic development of the spider crabs Leurocyclus tuberculosus and Libinia spinosa was divided into five periods based on the differentiation of: I) cleavage, II) embryonic primordium, III) optic lobes, IV) optic lobes pigmented and V) chromatophores presence. Different traits such as spines, setae and telson morphology distinguish the two species from period III until hatching. Egg volume was greater in Leurocyclus tuberculosus than in Libinia spinosa. The duration of each period was different during development. Whereas in Leurocyclus tuberculosus period II (morphogenesis) is the longest, in Libinia spinosa the period IV is the longest. Complete embryonic development at 14°C lasted 36.7 ± 3.1 days in Leurocyclus tuberculosus and 57.4 ± 4.4 days in Libinia spinosa.