Megalyra wagneri (MEGALYRIDAE)
Workbook
Found 19/8/24 dead on window sill inside house, almost certainly having emerged from sticks/logs brought inside for firewood. Collected and stored dry, specimen ID 2408B.
[now added to iNaturalist: https://inaturalist.ala.org.au/observations/240078833]
[Note that this is the second Megalyra I’ve found in the same way within the past few weeks. The other is #2406C. And I’m convinced that they are different species!]
Genus = Megalyra
Specimen 2408B ticks all the boxes for Megalyridae, including the 14 antennal segments, subantennal grooves, reduced wing venation, and mesosomal structure. For details, see the Megalyrid Hub page. Megalyra is the only representative of that family in Australia. The lack of a distinct forewing pterostigma, coarse sculpturing of the head and mesosoma, open radial cells of forewing, and absence of a postorbital carina are also indicative of this genus.
2. Species level ID … Megalyra wagneri (?)
First, I conclude that 2408B is a male … no ovipositor, and the base of the mandibles shows the same male-specific striations as reported in another species (M. troglodytes).
Working through my summary list of features for Australian megalyrids (based on Shaw, 1990), I can try to narrow down the options.
Not M. shuckardi. That widespread and quite common species is much larger, is densely setose, and has entirely dark wings.
Not M. spectabilis. A northern species which is also densely setose and has an exceptionally broad, dark medial group.
Not in the fascipennis species-group. The small size of 2408B alone rules out M. fascipennis and M. caudata … both are much larger. In addition, all three species in this group (which includes M. australia) have distinct lateral patches of setae along the metasoma, whereas 2408B has only sparse rows of long setae.
Not M. rufipes. This is a widespread species, and several features fit with 2408B, including colouration, setal arrangement, head shape dorsally, & size range (just) … but I exclude it on the shape of the frons and vertex. Diagnostic features for M. rufipes include “face protruberant ventrally; frons and vertex flattened” (Shaw, 1990. p. 1035). The frons and vertex of 2408B are rounded when viewed laterally.
Not others in rufipes species-group (M. transversistriata, M. viridescens). Although based on only a few females, both species are much larger than 2408B. Also, they have a broad, dark medial band on the forewing & the mesoscutum is much shorter.
Not in the minuta species-group. According to Shaw’s key, the presence of the forewing costal vein excludes this group. In addition, the head is more spherical (width/length ratio of 1.29 cf 1.48-2.07 among the minuta group species). It is also larger than most minuta.
This leaves the wagneri species-group … and M. wagneri does indeed seem a good fit, including:
body length. The 13 males in the sample ranged from 4.2-5.7mm body length. 2408B is 5.7mm.
head shape. Near spherical, with a range of 1.26-1.33. 2408B is 1.29
mesoscutum shape. Shaw’s males ranged from 0.73-0.83. I measured 2408B as just slightly longer at 0.87.
body colouration. Males body colour is all black, legs yellowish-brown to orange, coxae black. Hind femur colour varies and may to partly or wholly black. Antennal scape, pedicel, F1-2 brown to orange (otherwise black).
forewing colouration. Wing generally lightly infused, sometimes with irregular medial blotches (not forming a discrete band). The blotches in 2408B could almost be viewed as a band, but without type images for comparison it is difficult to interpret Shaw’s use of ‘discrete’. Certainly, the blotches are not clearly delineated as a band.
forewing venation. Shaw only provided a description for females: M+Cu1, Cu1, 1mcu and apex of Rs spectral (faint infumation). This is largely consistent with 2408B, although 1mcu is entirely absent.
hindwing venation. For females, Shaw describes the Rs vein as “complete to near wing margin” (p. 1050). This matches 2408B, if a accept ‘complete’ to include both tubular (clearly sclerotised) and strongly infumate (but not sclerotised) sections.
setae on body. Sparse, and not in dense patches.
location. This is a relatively common and widespread species, with collection sites from Cairns to Melbourne and west to south-west WA.
This species, as currently defined by Shaw, shows variation in a number of features. This could account for the difference I see in the ocellar arrangement. 2408B has the lateral ocelli closer to the eyes than would be seem to the case for those in Shaw’s collection. That is, I get a POL/OOL of 1.15, while Shaw’s range from 1.67-2.29.
extract from the species description for M. wagneri, pp. 1050-1:
Shaw, S.R. 1990. A taxonomic revision of the long-tailed wasps of the genus Megalyra Westwood (Hymenoptera: Megalyridae). Invertebrate Taxonomy 3: 1005-1052
The other two species in the wagneri species-group can be excluded on the bases of location (M. globula), hindwing venation (M. globula & M. plana), scutellum sculpture (M. plana).
A second (outside) possibility. Although 2408B is quite unlike M. lilliputiana as described by Shaw (1990), there is an additional specimen from Batemans Bay that probably warrants a closer look. The female collected in 1952 was considered a new species by Riek, but never formally described. Shaw (1990) states that apart from its larger size “it does not differ significantly from the type of lilliputiana” (p. 1028). However, given that the relative proximity of the collection site, it would be good to take a closer look at the specimen in ANIC. For example, does it have a costa? What is the head shape?
extract from the species description for M. lilliputiana, p. 1028:
Shaw, S.R. 1990. A taxonomic revision of the long-tailed wasps of the genus Megalyra Westwood (Hymenoptera: Megalyridae). Invertebrate Taxonomy 3: 1005-1052
References (see also Megalyrid Hub page):
Shaw, S.R. 1990. A taxonomic revision of the long-tailed wasps of the genus Megalyra Westwood (Hymenoptera: Megalyridae). Invertebrate Taxonomy 3: 1005-1052
This is a workbook page … a part of our website where we record the observations and references used in making species identifications. The notes will not necessarily be complete. They are a record for our own use, but we are happy to share this information with others.