. Bulletin of the Natural History Museum Geology. . Fig. 2 Chaoburmus breviusculus Lukashevich, , paratype NHM (1), female in Burmese amber. determined as Helokrenia sp. was found in the Purbeck Beds, England, Lower Cretaceous (Berriasian); Ed. Jarzembowski, pers. comm.). Besides the short, broad R3+4 and Ml+2 forks, Helokrenia and Chaoburmus are similar in their small size and short Sc (ending at r-m level), being distinct in the anal vein length. Though the anal vein wasn't figured in the description of Helokrenia nana (Kalugina & Kovalev, 1985: 80, fig. 38), it can be see
. Bulletin of the Natural History Museum Geology. . Fig. 2 Chaoburmus breviusculus Lukashevich, , paratype NHM (1), female in Burmese amber. determined as Helokrenia sp. was found in the Purbeck Beds, England, Lower Cretaceous (Berriasian); Ed. Jarzembowski, pers. comm.). Besides the short, broad R3+4 and Ml+2 forks, Helokrenia and Chaoburmus are similar in their small size and short Sc (ending at r-m level), being distinct in the anal vein length. Though the anal vein wasn't figured in the description of Helokrenia nana (Kalugina & Kovalev, 1985: 80, fig. 38), it can be seen in the holotype as a long vein ending distal to m-cu as usual. The English specimen possesses a long anal vein as well. The short Sc is characteristic of Jurassic Dixidae (another family of the same superfamily, known since the Jurassic) and the oldest chaoborid, Rhaetomyia and therefore con- sidered a plesiomorphy. Preimaginal stages remain unknown. The combination of other characters is too unusual to assign Chaoburmus to either Eucore- thrinae or Chaoborinae at present state of our knowledge (the balance of possible synapomorphies is in favour of Chaoborinae, see Table 1). Chaoburmus breviusculus sp. nov. Figs 1-4 Figs la, lb Chaoburmus breviusculus Lukashevich, , holotype NHM , male in Burmese amber; views from opposite sides. NAME. From Latin breviusculus - rather short, alluding to the length of first tarsomere compared to the second. Holotype. NHM , inclusion of a well preserved male; Burmese amber; probably, Late Cretaceous (see Zherikhin & Ross, this volume). PARATYPE. NHM (1) - a well preserved female originat- ing from the same piece of amber, but now separate. Description. Small densely pubescent midges with pale legs. Wing unspotted, three times as long as wide, veins with short macrotrichia. Rl slightly displaced forwards, terminating proximad or level with R3+4 furcation. R3+4 fork 2 (female) (male) times shorter than R3+
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