The gonads of Aegla platensis Schmitt (Decapoda, Anomura, Aeglidae): a macroscopic and histological perspective

The aim of this study is to characterize the gonads of Aegla platensis, relating aspects of colour and size of ovaries, testes and vasa deferentia (VD) to histological observations. The ovaries are H‐shaped, extending from behind the stomach and ending at the 1st or 2nd abdominal somite. The male has a pair of testes from which the VD issue and extend over the pereon. For males and females, macroscopic categories of gonad development are defined. Stages of the male gonad are defined as types 1, 2 and 3. Type 1 includes the less developed gonads, and type 3 includes extremely developed testes and completely differentiated VD. The ovaries are classified into four stages according to their colour: I (white), II (yellow), III (orange) and IV (red), beginning with the least developed gonads. The number and size of oogonia and oocytes depend on the stage of the ovary and coincide with the different degrees of development as indicated by ovary colour. In males, the presence or absence of spermatozoa in the testes and VD is determined only for the more developed gonads. Neither spermathecae (female) nor spermatophores (male) were found. The lack of spermatophore in the present species is a rare characteristic among the anomurans.