The genus Agraphydrus RÉGIMBART , 1903 (Coleoptera: Hydrophilidae) of the Republic of the Philippines is taxonomically reviewed aided by COI mtDNA barcodes. Nine new species are described, all currently regarded as endemic to the Philippines: A. abrasus sp.n., A. ampullatus sp.n., A. batak sp.n., A. brevilobatus sp.n., A. occultus sp.n., A. palawanensis sp.n., A. pelingeni sp.n., A. tenuipalpis sp.n., and A. zetteli sp.n. Agraphydrus coomani (O RCHYMONT , 1927), widespread in the Oriental and Australasian regions, is recorded from the Philippines for the first time. COI sequences and thorough morphological examination suggest that this and further species represent a group of closely related, partly cryptic species under current radiation. At least three of them are clearly distinguishable and summarized together with 16 other Oriental Agraphydrus species (A. coomani species group). Habitus, male genitalia and other morphological details are illustrated, distribution maps and a key to the species are presented. Their macro- and microhabitats are briefly discussed. All species are aquatic, although they were also caught at light and in emergence traps.
Albrecht Komarek, Hendrik Freitag, (2020), Taxonomic revision of Agraphydrus RÉGIMBART , 1903 V. Philippine species and their first DNA barcodes (Coleoptera: Hydrophilidae: Acidocerinae). Koleopterologische Rundschau / Coleopterological Review, 90, 201–242.