A Fine Morphological Study of the Rare Anillidris bruchi Santschi (Hymenoptera: Formicidae: Dolichoderinae) Male and Queen

Simple Summary: In this study, based on specimens collected in the city of Sao Paulo (Brazil), we redescribe and illustrate the rare Neotropical ant Anillidris bruchi male and queen by using optical and scanning electron microscopy (SEM), supplying new morphological distinctive characters, and improving the previous descriptions. This work will be useful for identifying the alate castes of this species and for using the characters of the male and queen to infer relationships with other dolichoderine ants. Using optical and scanning electron microscopy, we describe the following new morphologically distinctive characters of the rare Neotropical ant Anillidris bruchi Santschi, 1936, male and queen: scattered setae inter-ommatidia, semicircular hypostomal notch, antennal cleaning, metatibial spurs, and the remnant of the M2 vein in the hindwings. In males, we show for the first time the morphology of maxillary and labial palpi, the absence of metapleural glands, and, in external genitalia, for the first time in ants, a new mechano-sensory area on the volsella that we called "volsella sensorium", composed of several spine-like sensilla. Additionally, we give an updated morphological diagnosis of the alate caste, which will be useful for future studies to clarify the phylogeny of the genus Anillidris.