Reproduction and division of labour in Platythyrea cf. cribrinodis (Gerstaecker 1858) (Hymenoptera Formicidae): comparisons of individuals, colonies and species

Abstract

The social structure of three colonies of Platythyrea cf. cribrinodis (Gerstaecker 1858) (tribe Platythyreini) was compared. All three were queenless, diploid reproduction being performed by a single mated worker in each nest. Individual variability in behaviour mapped on to a distinct system of roles, perhaps mediated by the localization of tasks within the nests. The behaviour of the monomorphic workers was biased by their age, but not their size. Workers could be grouped according to their social role, each role having a spatially-localized focus, e.g. larvae or prey, in the nest. Colonies varied in the role structure of their work-force, probably as a function of the different contingencies in each nest. This general pattern resembled other queenless species of Platythyrea Roger 1863. The regulation of reproduction was identified as important in maintaining a cohesive division of labour in colonies of this species.

Mated workers shared a distinctive behavioural profile, and were not integrated into the work-force, unlike mated workers of P. schultzei Forel 1910 and P. lamellosa (Roger 1860).

Unlike other species of Platythyrea, reproduction in P. cf. cribrinodis seems to be regulated at the level of embryonic development, since virgin workers laid eggs that appear to be in viable. This mechanism was unknown in the genus. Regulation of receptivity to courtship may limit the number of mated ants in a colony.

Key Words:

• Ponerinae
• Platythyreini
• queenlessness
• roles
• polyethism
• reproduction