New staphyliniform beetles (Histeridae and Staphylinidae) from Iron Formation cave environments in Brazil

Beetles are recognized for their ability to inhabit a wide range of environments, including subterranean habitats, where they have achieved notable ecological success. In Brazil, research on beetle fauna has increased substantially, however this trend does not extend to cave-dwelling species. Staphyliniform beetles are no exception, and current knowledge of their subterranean representatives remains limited.

To address this gap, the present study describes two new taxa from the same Brazilian cave. One of these is a new species of Plagiogramma Tarsia in Curia, 1935 (Histeridae, Tribalinae), while the second taxon is the second species of the genus Tavakilianidia Orousset, 1985 (Staphylinidae, Osoriinae). For both taxa, this study represents the first record of these genera in cave environments and, for Tavakilianidia, the first record in Brazil.

Plagiogramma unicum Leivas, sp. nov., resembles P. amplistria Kovarik & Dégallier, 2021, but differs in its smaller size, light brown coloration, body dorsally and ventrally finely and sparsely punctate, reduced eyes, fronto-clypeal region strongly concave, a carinal striae of the prosternal keel that divergent anteriorly and subparallel posteriorly, and an indistinct median metaventral suture. Tavakilianidia flava Caron, sp. nov. differs from T. anophtalma Orousset, 1985 in having a lighter body, antennomeres 4–6 not pedicellate, and a perfectly globose spermatheca.

These findings increase the known diversity of these previously neglected beetle groups in Brazil and provide new insights into the biology of their genera.