This post is about a real jewel of an ant.
Most myrmecologists know Linepithema for the pestiferous Argentine ant L. humile, a small, brown, rather dull looking creature. The genus contains 18 other species, however, and not all are as drab. Check out Linepithema leucomelas:
This colorful ant is endemic to Brazil’s highly-endangered Atlantic coastal rainforest. I spent 6 years working on the taxonomy of this genus for my Ph.D., yet I never saw a living L. leucomelas until Mrs. Myrmecos & I traveled to Paraná in May. I’m not generally one to keep a life-list of ant sightings, but this was a species I was thrilled to find.
The nest occupied narrow spaces between dead leaves at the base of a bromeliad, as I’d expected from previous literature records. The ants’ unusual coloration may serve as a sort of camouflage. Individual workers were difficult to see against a mottled background, especially when moving. They appeared like sprightly little ghosts, while their various dark spots made discerning the head from the tail surprisingly hard.
While identification of L. leucomelas would seem straightforward from the color, the genus Tapinoma has produced a sympatric ant of similar patterning, Tapinoma atriceps. The latter species is stubbier, with the waist constriction concealed under the gaster, and the two ants smell differently when squished. Any ecological reasons underlying the apparent mimicry of the two species are unknown. As for most tropical insects, neither species has received scientific attention beyond the initial taxonomic description.