ICHNEUMONIDAE: : Megastylus Schiodte 1838
Diagnosis:Characteristics of Megastylus include: 1. Body size <10mm; 2. Position of spiracle on T1 at, close to, or before centre; 3. Shape of aerolet in forewing varies, usually pentagonal (open) but sometimes aerolet absent; 4. Colour of face variable; 5. Metasoma somehwat compressed dorsal-ventrally; 6. Size of ocelli varies (medium - small); 7. Length of antennae as long, or longer than body; 8. Length of ovipositor barely visible; 9. Wings present; 10. Colour of wings hyaline (clear); 11. Sternaulus varies (absent, short, long); 12. Shape of face in lateral view is weakly bulging; 13. Sternite on T1 (viewed laterally) extending past spiracle sometimes forming a long cylinder with tergite; 14. Shape of T1 (viewed laterally) elongate (tube-like), evenly curved; 15. Number of teeth in mandibles 2; 16. Metasoma yellow/brown/black with simialr coloured stripes and bands; 17. Length of T1 longer than T2; 18. Sculpture on mesoscutum smooth, very polished; 19. Width of T1 (viewed dorsally) uniform width (slightly widening posteriorly); 20. Glymma on T1 absent; 21. Sculpture on metasoma smooth with a semi-glossy or satin appearance at least on T2; 22. Propodeum reaching past coxal insertion, but not reaching halfway along metacoxae.
Similarity to Other TaxaMegastylus are most similar to Helictes . However, in Megastylus the antennal scape is 'goblet-shaped' (strongly obliquely truncate), whereas in Helictes the antennal scape is short but cylindrical.
Megastylus can be confused with some Cryptinae (especially Aclastus ), but these have a much more distinct ovipositor, and a more well defined pentagonal areolet.
Distribution in NZ
North Island: ND, AK, BP, CL, GB, HB, TO, WN. South Island: NN, SD, BR, MB, MC, DN, CO, OL, WD, FD, MK.
Species in NZEstimated at least ten undescribed endemic species.
Biology & hostsMegastylus is a large genus, with many species commonly encountered in wet forest habitats across the world (Gauld 1984). Little information is available on the genus in New Zealand. However, they are widespread and commonly collected from a range of habitats, including: orchards, urban, estuary, forest/bush and tussock.
Sources of informationGauld ID 1984. An Introduction to the Ichneumonidae of Australia. London, British Museum (Natural History). 413 p.
CitationWard DF & Schnitzler FR. 2013. Ichneumonidae of New Zealand. Genus Megastylus http://ichneumonidae.landcareresearch.co.nz
Accessed: 19 October 2019