Rhizomyia Kieffer, 1898: 56.

T y p e s p e c i e s: Rhizomyia perplexa Kieffer, 1898: 57 (monotypy).

D i a g n o s i s (fig. 5, 1–8, 7, 6, 7). Wing, body and legs are conspicuously covered by scales. Head almost completely covered by eyes or eye bridge wide. Antennae are 2+9–10-segmented. Male flagellomeres are subcylindrical with neck and swollen basal enlargement with numerous swollen peritremae of setae. Neck of male middle flagellomeres is longer, equal or slightly shorter than basal enlargement. Female flagellomeres are elongated, sessile, subcylindrical, without neck or with very short neck. Male fore tarsi usually with teeth, middle and hind tarsi with or without teeth. Palpi are 3–4-segmented, labrum is triangular. Wing is broad, R1+2 joins costa before its midlength. R4+5 is straight, joining C rather near wing apex or at wing apex; C broken at junction with R4+5; Cu forked. Claws with tooth. Genitalia are transversal. Gonocoxites are short, ovoid or parallel-sided. Gonostylus is long, narrowing apically, terminated by very little apical claw. Cerci with very deep excision. Hypoproct is slightly caved or excavated. Aedeagus is usually shorter than gonocoxites or equal in length. Basal outgrowths (or parameres) of gonocoxites absent. Ovipositor very short, not protrusible, apically with two terminal lamellae.

S p e c i e s i n c l u d e d. Holarctic and Oriental genus with 29 species, 21 of them Palaearctic ones (Skuhravá, 1997; Mamaev, 1998; Mamaev, Zaitzev, 2002; Fedotova, 2004; Gagné, 2004, 2010; Fedotova, Sidorenko, 2005, 2006 b). Extinct species of Rhizomyia were unknown until now.

B i o l o g y. Larvae of Rhizomyia perplexa Kieffer, 1898 and R. circumspinosa (Rübsaamen, 1899) develop on roots and in sheath of leaves of a sedge (Carex spp., Cyperaceae) (Mamaev, Krivosheina, 1965).