Cowanomyia hillaryi Jaschhof & Jaschhof

Jaschhof, Mathias & Jaschhof, Catrin, 2009, Cowanomyia hillaryi gen. et sp. n., a remarkable new gnoristine (Diptera: Mycetophilidae: Sciophilinae) from New Zealand, Zootaxa 2117, pp. 43-48 : 45-47

Cowanomyia hillaryi Jaschhof & Jaschhof new species

( Figs 1–7 )

Description. Male. Head. Figs 1–2 . Antennal flagellomeres 3–5, see Fig. 4 .

Thorax. Fig. 5 . Wing. Fig. 3 . Length 1.5 mm.

Male terminalia. Figs 6–7 . Not rotated. Sternite 9 not traceable. Tergite 9 with straight apical margin and strongly concave basal margin, setae concentrated apicolaterally. Gonocoxites broadly merged ventrobasally, ventrobasal portion without mesal and basal setae; apicolateral processes terminating in narrow, bare projections that cross each other. Gonostylus inserted at midlength of gonocoxite, elongate, narrow, with apical broadening and 2 fine subapical setulae, otherwise bare. Ejaculatory apodeme with rodlike basal portion and complex, rhomb-shaped apical extension. Aedeagus/paramere complex largely membranous. Sternite 10 unipartite, with 2 large apical setae. Cerci rounded, with numerous dorsal and 4 large apical setae.

Etymology. We name this new species in memory of Sir Edmund Hillary, the Patron of the New Zealand Native Forests Restoration Trust until his death in January 2008, and to honour the Trust´s dedicated work from which forest-dwelling arthropods, such as fungus gnats, should benefit greatly.

Types. Holotype. Male, New Zealand, South Island, Westland, Westland National Park, Canavan´s Knob, in grassy clearing in mixed podocarp forest, 140 m, Oct.–Nov. 1982, by Malaise trap, A. B. Miller (in NZAC). Paratypes. 2 males, same data as the holotype (in NZAC and SMTD).

Discussion. Cowanomyia and Adicroneura are the only Mycetophilidae known to have only one complete median branch in combination with a furcate anterior cubitus. Apart from that, these two genera have little in common and are evidently not closely related. Even their vein patterns include a number of differences (character states in Cowanomyia in parentheses): in Adicroneura biocellata , the type spcies, Sc is strong and reaches C (faint and ending free); R1 is very long and ends far in the distal half of the wing (much shorter and ending in the basal half of the wing); Rs and r-m form almost a right angle (oblique); the basal half of M is very faint (M is comparatively faint throughout); and all longitudinal veins except CuP are described to have dorsal and ventral setae (only dorsal setae present on R, R1 and a part of R5). As regards characters other than those of wing, in Adicroneura biocellata the mesal ocellus is missing (present); mediotergite and laterotergites are setose (asetose); the hind coxae bear a vertical row of setae (such row absent); and the fore tibial organ is missing (well developed). There might be further differences, for instance in thorax structure, which however do not become apparent from Vockeroth´s description that does not fully illustrate the thorax of A. biocellata . Matile (1995) described and discussed a number of morphological differences between A. biocellata , on the one hand, and A. meridionalis and disjuncta , on the other hand. Contrary to his conclusion, we are not convinced that the species from Chile are congeneric with the type species. Further, there is no indication for the affinity of the two Chilean species and Cowanomyia hillaryi . If our view is correct, then the Adicroneura - like vein pattern must have evolved two or even three times in Mycetophilidae .

The genus Cowanomyia fits well the diagnosis for the Gnoristini as revised by Väisänen (1986: 203), irrespective of the fact that he did not distinguish between apomorphous and plesiomorphous character states. Characters supporting the affiliation of Cowanomyia to the Gnoristini are: the presence of 3 ocelli, the laterals distant from the eye margins; the sharply delimited sensory depression on the third palpus segment; the anapleural suture declining posteriorly; the bare mediotergite; the absence of setae on the wing membrane; the short, oblique r-m; CuA with a long stem; and CuA2 evenly bent, not sinuous. Among Gnoristini sensu Väisänen (1986), Cowanomyia is peculiar for its enlarged proepimeron; the lack of distinct bare stripes on the scutum; the faint, free-ending Sc; the short R1; the one-branched media; and the sparsely setose hind coxae. Some of these peculiarities, such as those regarding wings and legs, might result from miniaturisation: Cowanomyia males are among the smallest mycetophilids known to us and are actually as small as the micromyid gall midges with which they share the similar venation pattern.

Due to its peculiar assemblage of characters, the relationship of Cowanomyia to other Gnoristini remains obscure. To our knowledge there are no gnoristines in New Zealand and Australia, particularly Tasmania, in which adult morphology indicates an affinity to Cowanomyia . The same applies to the Gnoristini described from other southern hemisphere landmasses, which however are poorly known even on the generic level. For the time being this remarkable new genus holds an undefined position among world Gnoristini, both extant and fossil.

Figures

FIGURES 1 – 4. Cowanomyia hillaryi gen. et sp. n., male. 1: Head, lateral view. 2: Head, frontal view. 3: Wing, dorsal view, alar microtrichia and marginal setae drawn only partially. 4: Antennal flagellomeres 3 – 5, lateral view. Length of scale bar = 0.1 mm (for 1 and 2), 0.5 mm (for 3) and 0.05 mm (for 4).

FIGURES 5 – 7. Cowanomyia hillaryi gen. et sp. n., male. 5: Thorax, lateral view. 6: Terminalia, ventral view. 7: Terminalia, dorsal view. Length of scale bar = 0.1 mm (for 5) and 0.05 mm (for 6 and 7).