Key to males of the world species of Pachyseius

1. Peritrematal shield fused exopodal shields; holoventral shield present; spermatodactyl long and pointed tip............................................................................................... P. quadrigeminus sp. nov.

- Peritrematal shields free, not fused with exopodal shields; sternogenital and ventri-anal shields present; spermatodactyl short and with truncate tip................................................................................... 2

2. Almost all dorsal shield setae slightly spatulate; anterior section of ventri-anal shield well expanded, much longer than posterior section of sternogenital shield...................................................... P. iraola Moraza, 1993

- Almost all dorsal shield setae needle like; anterior part of ventri-anal shield equal length to posterior section of sternogenital shield....................................................................... P. anisimovi Marchenko, 2015