A newly identified ant species in Japan exists without males or workers, a finding researchers describe as unprecedented in the insect world, according to Stern. A Japanese-German team that included zoologist Jürgen Heinze of the University of Regensburg documented the species, Temnothorax kinomurai. They called it a “spectacular discovery” that breaks typical social rules and has not been observed in any other ant species.
In most ants, infertile workers and short-lived males support reproductive queens. This species departs entirely from that model by consisting only of queens, according to Scinexx. Biologists determined that T. kinomurai produces offspring from unfertilized eggs, creating a queen-only lineage without males or workers. The team documented the queen-only system through field and laboratory observations. This absence of both workers and males distinguishes T. kinomurai from all known ant taxa and places it outside the standard eusocial template.
The reproductive strategy hinges on takeover behavior. Queens invade nests of the closely related species Temnothorax makora, kill the resident queen and some workers, and seize control. The surviving workers end up rearing the intruders’ offspring, which develop into new T. kinomurai queens from eggs laid after the takeover, according to Die Presse. The host colony’s labor force remains intact enough to sustain the nest, but its reproductive future is redirected to produce the invading species’ queens.
To confirm how the species reproduces, scientists examined the ants’ bodies, focusing on reproductive anatomy. The queens’ spermathecae were smaller than expected and empty. This showed no mating had occurred and that the species propagates through parthenogenesis. The anatomical evidence supports the takeover observations and the absence of males, reinforcing that the life cycle is maintained entirely by unmated queens.
The researchers also proposed an evolutionary pathway. They hypothesize that T. kinomurai evolved from a slave-making ancestor that relied on other species for colony labor. Its own worker caste was gradually lost because outside workers shouldered those duties. The loss of male production occurred later in the lineage’s evolution.