A systematic revision of the aleocharine genus Rothium is presented. Rothium is redescribed, and five species are recognized, three of which are described as new (R. pallidus Ahn and Ashe, Type locality – Acapulco, Mexico, R. ashlocki Ahn and Ashe, Type locality – Punta Galera, Ecuador). Types and paratypes of the three new species are designated. The late-instar larva of R. sonorensis is redescribed and compared with that of R. giulianii. A key is provided for separation of known species of Rothium and illustrations of diagnostic features are provided. Rothium is hypothesized to be related to the tribes Myllaenini and Pronomaeini rather than the tribe Homalotini based on the very small gland opening on the anterior margin of tergite VII; antero-lateral angles of mentum prolonged into spinose processes; lacinia of maxilla elongate, slender, with distinctive distribution of spines interdigitating with spinose scales; galea shorter and much more slender than lacinia, with distinctive small patch of setae on apex, and without setae on mesal edge; base of galea flexible, allowing galeal base to bend at a right angle; cardo of maxilla very elongate; ligula short and entire; medial pseudopore field narrow, with few or no pseudopores; lateral pseudopore fields of prementum without pseudopores; and, labial palpi elongate. A cladistic analysis of the species of Rothium is presented. |