Novel blend of life history traits in an inquiline ant, Temnothorax minutissimus, with description of the male (Hymenoptera: Formicidae)

Buschinger, A.; Linksvayer, T.A.

Abstract: Forty-five colonies of Temnothorax curvispinosus (Mayr, 1866) containing the rare inquiline ant T. minutissimus (Smith, 1942) have been collected near Bloomington, Indiana, USA. The colonies were censused and some were kept in laboratory culture. Dealate and alate females of T. curvispinosus and T. minutissimus were dissected. The parasite females have a total of six ovarioles. Both, T. minutissimus and the host species, are facultatively polygynous, and the parasite is host-queen tolerant. Alate males were found in August and September. High numbers of alate and dealate, mated but not yet reproductive, young females of T. minutissimus were present in colonies collected in early spring, a feature which had been known as "Intranidal Mated Offspring Hibernation" (IMOH). Mated young queens of T. minutissimus seem to disperse in spring to invade host colonies. Apparently they are accepted quite easily by host colonies. Rearing of colonies collected in the early spring, or hibernated in the laboratory, yielded first a brood of sexuals of T. curvispinosus, and subsequently considerable numbers of gyne pupae of T. minutissimus appeared. Only very few males were produced (sex ratio about 0.1 ♂/♀). Intranidal mating attempts were observed, and newly mated young females were detected in colonies having reared gynes and males of T. minutissimus. Life history of the species thus is a novel combination of traits found in different other parasitic ant species: Intranidal mating and Imoh as in a few European "degenerate slavemakers" of the genus Myrmoxenus, but the parasite is host-queen tolerant, as is the case in two of the three European inquiline species of Leptothorax (former Doronomyrmex). The development of the parasites after the host species sexuals is a novel trait. The male of T. minutissimus is described. It is characterized by a reduced number of antennomeres (9-11 instead of 12), and a certain "morphological feminization". Open access, licensed under CC BY 4.0. © 2004 The Author(s).

Myrmecologische Nachrichten 6: 67-76; printable