Madagascar, the real Treasure Island! Malagasy uncharted diversity of a rare ancient lineage of armored harvestmen (Opiliones, Laniatores, Buemarinoidae)

Buemarinoidae Karaman, 2019 is an ancient lineage of armored harvestmen that comprises six genera with a widely disjunct distribution: Arbasus (Simon, 1911) from some caves in France, Buemarinoa Roewer, 1956, from some caves in Sardinia, Italy, Flavonuncia Lawrence, 1959, endemic to Madagascar, Fumontana Shear, 1977, found in the southern Appalachians, United States, Turonychus Derkarabetian Prieto & Giribet, 2021, from a cave in Spain and Phocyx Porto, Monnod & Pérez-González, 2024, from Australia. The examination of a large series of 375 specimens of Malagasy buemarinoids allows us to redescribe the type species Flavonuncia pupilla Lawrence, 1959, and describe four new species: Flavonuncia ubicki n. sp., Flavonuncia mahaka n. sp., Flavonuncia vazimba n. sp. and Flavonuncia zanahary n. sp. We found that male genitalia represent key elements in the taxonomy of this group. The genus Flavonuncia now comprises five species, making it the sole non-monotypic genus within Buemarinoidae. The Malagasy fauna of Flavonuncia represents an interesting and unique opportunity to study the diversification process of an ancient lineage where the majority of the species are extinct and are currently represented by rare relict taxa.