Thrinchostoma (Diagonozus) asianum sp. nov.: Discovery of an African Subgenus of Long-malared Halictine Bees from Sumatra, with some Observations on its Oligotrophy to Impatiens

Thrinchostoma asianum sp. nov. is described from Sumatra as the first record of the subgenus Diagonozus known by four African species. T. asianum shares the unusually long lower part of the head with these species but is less differentiated in some features. This species is probably oligo-trophic to Impatiens korthalsii flowers.