AbstractAcrostichus puri n. sp., isolated from the body of a sweat bee, Augochlora pura mosieri, is described and figured. The new species is morphologically, molecularly and biologically very similar to A. halicti, i.e., these two species share a very complicated gubernaculum structure, distally hooked spicules with a triangular flap-like rostrum, stomatal polymorphism and synchronised associations with halcitid bees. The new species can be distinguished from A. halicti by its spicule morphology, distinctive squared manubrium and sharply bent (= ca 90° or L-shaped) distal tip vs an indistinctive rounded manubrium and a strongly recurved (= ca 180° or U-shaped) distal tip; gubernaculum with narrower, longer, anterior part and more complex posterior part than A. halicti, and tail of both sexes, with a long and filiform spike on the male or female tail vs a short spike (male) or conical tail (female). These two species also differ from each other by significant molecular sequence differences in SSU (2.0%), D2/D3 LSU (4.5%) and mtCOI (9.2%), and are reproductively incompatible in mating tests.