The mating behaviour of the seed shrimpParapolycope spiralis(Ostracoda: Cladocopina), with insight into the evolution of mating systems in cryptic interstitial habitats

Abstract

The mating behaviour of the interstitial ostracod Parapolycope spiralis Tanaka & Tsukagoshi, 2010 is reported here for the first time. This species is adapted to an interstitial environment, and is typified by having tiny body size and being completely blind. In this paper it is presumed that the characteristics of the mating behaviour are typical for species in an interstitial environment. Observations by microscopy on mating behaviour in the laboratory showed various distinct stages: (1) the male captures the female by a sucker on the antennula; (2) the male clasps and maintains the mating position using the endopodite, the endopodite claw, and the exopodite of the antenna; (3) the male makes contact using the distal part of the upper lip; and (4) copulation takes place. These observations indicate that the sequence of stages of the mating behaviour of miniaturized animals is not necessarily always a simplified process. During the process, it seems that the male upper lip establishes physical contact stimuli with the female. Because the interstitial environment is cryptic and consists of a three-dimensional space with reduced connectivity, direct physical contact is likely to be one of the most effective and successful courtship behaviours.