Asiorrhina, Blagoderov, Vladimir, Hippa, Heikki & Ík, Jan Šev Č, 2009

Blagoderov, Vladimir, Hippa, Heikki & Ík, Jan Šev Č, 2009, Asiorrhina, a new Oriental genus of Lygistorrhinidae (Diptera: Sciaroidea) and its phylogenetic position, Zootaxa 2295, pp. 31-45 : 35-37

Asiorrhina gen. nov.

Type species Lygistorrhina asiatica Senior-White, 1922

Differential diagnosis. The genus Asiorrhina differs from all other Lygistorrhinidae , both Recent and fossil except Palaeognoriste , in the double-lobed apex of the gonostylus. Asiorrhina is distinguished from all other Recent Lygistorrhinidae by having the apodeme of the male tergite 9 directed dorsad, not anteriad, and the tibial organ having a comb-like transverse row of stout vestiture and a flap-like lobe on its distal side, the latter character probably also distinguishing the unknown females. Seguyola , Loyugesa , Blagorrhina, Gracillorhina and Labellorrhina lack a recognizable tibial organ. In Lygistorrhina and Probolaeus there is a row of setae but these setae are fine and situated more apically. The exact structure of the tibial organ in Palaeognoriste is unknown, but the specimens we have studied probably do not have an organ similar to Asiorrhina . The genus Asiorrhina resembles Gracillorrhina in having the labium medially divided only on the apical part and by having the antennal flagellomeres flattened and expanded. In Gracillorrhina, however, the proboscis is very short, less than half the height of the head, and the flagellomeres are expanded only over the basal two thirds. Asiorrhina , like Blagorrhina and Gracillorhina, but not Palaeognoriste and the rest of the Recent Lygistorrhinidae , has pointed, not blunt mid tarsal claws.

Description. Small Lygistorrhinidae with medium-length proboscis.

Head. Number of ocelli three or two. Compound eyes widely separated, all facets/ommatidia equal in size, interommatidial setae longer than the diameter of ommatidium. Frons and vertex short setose, frons without conspicuously strong setae laterally. Face non-setose. Clypeus setose. Labrum setose. Proboscis about 1.5- 2 x height of head. Maxillary palpus a little longer than half of length of labellum. Labellum entire, only shortly divided at extreme apex ( Fig. 2 ). Hypopharynx nearly as long as labium. Antenna about two and a half times height of head. Flagellomeres flattened, broader than long, setosity uniform. Number of flagellomeres 14. Flagellomeres 1–13 with several strong dorsal setae; flagellomere 14 with a small constricted nib, more clear in A. parasiatica than in A. asiatica .

Thorax. Scutum roundly dome-shaped, anteriorly extending to the same level as base of coxa 1, setae evenly distributed, without a non-setose stripe between medial and lateral setae. Mediotergite evenly curved, bare. Posterior margin of metepisternum only slightly longer than anterior, not extending level of ventral margin of laterotergite. Pleural pit indistinct. Laterotergite slightly lobe-like posteroventrally, setose. Posterior margin of metepisternum only slightly longer than anterior, not extending level of ventral margin of laterotergite.

Legs. Long: tibia 1 slightly longer than scutum plus scutellum. Coxa 1 equal in length to coxa 3, coxa 2 conspicuously longer, its apex reaching the apex of coxa 3. Femora thickened, femur 3 thickest. Tibia 1 longer than femur 1. Tibial setae in rows. Tibial microtrichia absent. Tibia 1 with one spur, tibia 2 and 3 with two spurs. Tibia 3 rather slender, not club-like swollen on apical part, with transverse comb of strong setae subapically on prolateral side. Tibial organ on tibia 1 composed of transverse comb-like row of stout setae and flap-like lobe on the distal side of it ( Figs. 4 B, C). Basitarsomere 3 slender, slightly broader than basitarsomere 1, narrower than basal part of tibia 3.

Wing ( Fig. 5 ) relatively wide, length about 2.5x width; unicolorous greyish brown. Microtrichia on membrane short, 0.01-0.012 mm. Sc complete, weak and short, ending on costa. R1 meeting C at middle of wing. Costa reaches wing apex, ends at 5/6th of distance between R5 and M1 apices. RS not apparent. M1 and M2 basally weak but medial fork complete ( A. parasiatica ) or extreme basal part of M1 not visible so that medial fork absent ( A. asiatica ). C setose, R1 dorsally setose, other veins non-setose. Posterior margin of wing with alternating longer (dorsal) and shorter trichia. Haltere short, about half length of thorax.

Abdomen. Male sternite 8 simple. Setosity of male tergite 9 uniform or setae at apical part shorter and more curved; apodeme of tergite 9 short, without distinct stalk and directed dorsally. Gonostylus narrow, with two apical lobes. One long flagellate seta on mesial surface of gonostylus situated at midlength, not on basal half. Medial structures of hypopygium, parameres, tegmen and aedeagus, not studied.

Etymology. The generic name is a combination of Asia, with reference to the place of origin of the taxon, and - rrhina, a common ending in generic names in the family, derived from the Greek rhis, nose. The name is feminine.

Comments. Although the wing venation of Asiorrhina plesiomorphically resembles that of Palaeognoriste , phylogenetic analysis undoubtedly places it with the rest of Recent Lygistorrhinidae .

Figures

FIGURE 2. Male head, frontal view. A: Asiorrhina asiatica (Senior-White), comb. n.; B: Asiorrhina parasiatica, sp. n. (holotype).

FIGURE 4. Thorax, lateral view, (A) and tibial organ (B, C) of Asiorrhina. A, C: Asiorrhina parasiatica, sp. n. (holotype); B: Asiorrhina asiatica (Senior-White), comb. n.

FIGURE 5. Wings, dorsal view. A: Asiorrhina asiatica (Senior-White), comb. n.; B: Asiorrhina parasiatica, sp. n.; scale 0.5 mm.