First reported occurrence of a heteromorph antennule in the freshwater prawn Macrobrachium acanthurus (Wiegmann, 1836) (Decapoda, Caridea)

Abstract

In contrast with holometabolous insects, crustaceans undergo periodic shedding of the old exoskeleton (ecdysis) throughout their adult life. The occurrence of successive moultings indicates that crustaceans can regenerate lost or damaged limbs, including the eye (Ventura et al., 2018), through the moulting cycle (Chang & Mykles, 2011). The eyes, however, are not always perfectly regenerated, resulting in an anomaly known as heteromorphosis, which is the regeneration of an appendage in a foreign location, generally as a response to a natural injury or artificial ablation (Bliss, 1960; Nevin & Malecha, 1991). Heteromorphic development, although considered rare, has been acknowledged since 1864 (Milne-Edwards, 1864), and was summarized for decapods by Von Buddenbrock (1954), who states that the most striking type of heteromorphosis was the growth of an appendage similar to an antenna or antennule in the expected position of one or both eyes.