Background:

The study of the morphological changes in embryonic development up to the stages of zoea and megalopa, is essential for the culture of crustacean and to distinguish one species from another in the classification of the decapods.

Goals:

Identify the morphological characteristics of the first zoea of Stenorhynchus debilis (Smith, 1871), to differentiate from the first zoeas of species of the same genus.

Methods:

S. debilis ovigerous females were collected and kept in captivity. From spawned eggs the stage of embryonic development was identified and the morphology of the first zoea was studied, using a bright field microscope equipped with a digital camera and Image Pro® software.

Results:

The orange eggs are 380-450 µm of diameter. The embryonic identified stages were: multiple divisions, blastula, gastrula and pre-zoea. The following morphological characteristics of the first zoea were identified: the straight spine 10% larger than the length of the carapace; a triangular spine in the frontal region of the carapace, a pair of chromatophores in the vicinity of each somite and fur branches of the telson with large and curved terminal spines.

Conclusions:

These morphological characteristics of the first zoea of S. debilis make it possible differentiate from the first zoeas of the same genus, such as S. seticornis and S. lanceolatus.