A new species of Smicromorpha ( Hymenoptera , Chalcididae ) from Vietnam , with notes on the host association of the genus D

Smicromorpha masneri Darling, sp. n. is described from Bach Ma National Park, Th ua Th ien-Hue Province, Vietnam. Th is is the fi rst confi rmed record for the genus on mainland southeast Asia. It is generally accepted that species of Smicromorpha are parasitoids of green tree or weaver ants, Oecophylla smaragdina (Fabricius) but this is fi rst rearing record of these parasitoids from the nests of weaver ants.


Introduction
Th e genus Smicromorpha remains "the least known and perhaps the most bizarre subfamily of chalcidid wasps" (Naumann 1986).Th ese wasps -there are currently 6 described species distributed across Southeast Asia -may not even be a subfamily in a phylogenetic system.Based on morphological characters, Wijesekara (1997) argues that Smicomorphinae is not a clade but rather a highly derived genus of Chalcidini (Chalcidinae).Th is hypothesis is certainly not universally accepted (e.g.Bouček 1988) and ongoing molecular studies have yet to clarify the affi nities of Smicromorpha, but preliminary results suggest they are not members of Chalcidini (John Heraty, pers. comm.).About the best we can do at the present time is regale in the notable features of this enigmatic genus, which includes pale coloration, huge eyes and ocelli, and narrow metasoma inserted high on the propodeum (Figure 1).
Th e center of species diversity and abundance of the genus is in Australia.It is therefore not surprising that Smicromorpha attracted the attention of A.A. Girault, who published information including the description of the genus in fi ve papers between 1913 and 1930.Th e genus received little attention for the next fi ve decades.Smicromorpha keralensis was described from southern India (Narendran 1979), but, as noted by Naumann (1986), the genus was represented in collections by "a handful of specimens, most of which were in poor condition".Extensive collecting along the northern coast of Australia in the 1970s and 1980s dramatically increased the number and the quality of the specimens in Australian collections.Th is collecting eff ort resulted in a comprehensive revision of the genus with the description of three new species and illustrations and standardized descriptions of the six species in the genus.Th e descriptive format in Naumann (1986) was in some ways idiosyncratic for Chalcidoidea, but will be used herein with some modifi cations for the new species from Vietnam to allow comparisons with the previously described species.
Smicromorpha is generally regarded as an associate of weaver ants in Australia.Naumann (1986), citing Girault (1913), states that S. doddi is a parasitoid of the larvae of the green tree or weaver ant (Formicinae).Th is host association is credited to the noted Australian entomologist F.P. Dodd.Girault (1913) states that "Mr.Dodd informed me that this species is parasitic upon larvae of the green ant, Oecophylla smaragdina, depositing eggs upon them when the workers are using their silk-spinning larvae for the purpose of binding the leaves together when building a new nest".F. P. Dodd was a "phenomenal observer" (Geoff Monteith, in litt.) and naturalist and spent a great deal of time studying weaver ants (Montieth 1991).Th ere are also reports of Smicromorpha hovering near nests of O. smaragdina (Naumann 1986:176 for S. minera, Narendran 1979:201 for S. keralensis andGeoff Monteith, in litt.).Strong circumstantial evidence for this host association comes from the geographic distributions of Smicromorpha and Oecophylla in Australia.Naumann (1986) illustrated the concordance of their distribution maps in northern Australia (his fi g. 2).However, this host association is still regarded as anecdotal.Naumann (1986) further states that specimens have not been reared from weaver ant nests and Bouček (1980) notes that this host association has not been confi rmed.
Given the broadly overlapping distributions of Smicromorpha and weaver ants in Australia and India, it is somewhat surprising that Smicromorpha has not been recorded from mainland southeast Asia.Oecophylla smaragdina ranges from southern India across almost all of tropical Asia (Hölldobler 1983) and north to southern China.Th e only literature report of Smicromorpha for mainland southeast Asia is an undescribed species (and genus?) from Singapore (Bouček 1988).
In this paper I describe a new species that confi rms the presence of Smicromorpha on mainland southeast Asia, and provide rearing information which strongly suggests that weaver ants (Oecophylla) are the hosts of these parasitoids.

Materials and methods
Th e format of the description follows Naumann (1986) to permit comparison with the standardized descriptions of the previously described species, with a few exceptions.Naumanns's terms for the carinae on the mesopleuron are not used (e.g., sternalus, omaulus); these are not generally used for descriptive purposes in Chalcidoidea.Terms not discussed in Naumann (1986) follow Gibson (1997).Th e clava, as Naumann notes is "unsegmented, hardly diff erentiated" and the fl agellar segments are herein simply numbered; in females F7 is the clava (sensu Naumann).Measurements also follow Naumann (1986).Th e new species is most similar to S. lagynos Naumann (see below) and specifi c side-by-side comparisons were made with a paratype female: Australia, Northern Territory, Bramston Beach, near Innisfail, 30.IV.1967, D.H. Colless, open savannah (ANIC Database No. 32 004729).Unless noted in the description, the characters agree with S. lagynos based on both this paratype and the original description.Th e only additional character added to the description was the dorsal carina on the petiole (Fig. 10, dc).Identifi ed specimens of the following species were examined to understand alternative character states (all ANIC): S. doddi, S. banksi, S. minera and S. keralensis.
Type material will be deposited at the Royal Ontario Museum, Toronto, Canada (ROME) and the Institute for Ecology and Biological Resources, Hanoi, Vietnam (IEBR).Amplifi ed DNA from paratype female #1 is deposited at the University of California, Riverside (UCR: contact, John Heraty).Comparative material, which formed the basis of Naumann's (1986) revision of the genus, was obtained on loan from the Australian National Insect Collection, Canberra, Australia (ANIC).
Petiole: Length/width approximately 3.5, length/height 3.6-4.1 (Figs. 5, 9).Dorsally minutely reticulate-punctate, without paired dorsal carinae (Fig. 9, cf.Fig. 10, S Diagnosis.Th is species is most similar to S. lagynos and will run to that species in the key of Naumann (1986).Diff erences noted in the description above are diagnostic with respect to S. lagynos.Smicromorpha masneri is most easily distinguished from other species of the genus by the shape and sculpture of the petiole  in combination with the size of the transverse lamina at the base of the petiole (Naumann 1986, his fi gs. 22, 24).Smicromorpha masneri does not have the strong paired dorsal carinae at the base of the petiole characteristic of S. lagynos (Fig. 10).In addition, S. masneri has distinct tentorial pits, which are absent in S. lagynos.Females of each of the other described species of the Smicromorpha have  Variation.Th ere is variation in the segmentation of the antenna in the type series of S. masneri, specifi cally concerning the apical fl agellomeres.In the holotype, the left antenna is collapsed and the right is slide-mounted.Figure 3 illustrates the right antenna and F6 and F7 are at least partially fused and the diff erentiation between the articles is most evident by the placement of the multiporus plate sensilla.Th is fusion of F6 and F7 is also evident in the paratypes but only for the left antennae (paratypes #2 and #3).In paratype #1(both antennae) and paratypes #2 and #3 (both right), F6 and F7 are distinctly separated and F7 is the same length as F6 and only slightly narrower than F6 (Fig. 3, inset).Th e signifi cance and occurrence of this variation in other species cannot be evaluated at this time.Naumann (1986) was uncharacteristically non-committal about the antennae of females and did not present relative measurements of F6 and F7 (his "clava") and only illustrated the female antenna of a single species.My notes taken at the ANIC in March 2001 indicate that similar variation occurs in other species of the genus but a much more comprehensive study would be required to fully document and understand this variability.I present these comments primarily as an explanation for Figure 3 and so that future workers will not suff er the anxiety that I have had while trying to reconcile the antennal structure under an assumption of bilateral symmetry.
Notwithstanding the above, the size of the clava and distal fl agellar segment (e.g., F6) does appear to have diagnostic value for males and females of the genus (Naumann 1986, his fi gs. 3-7).For example, when diff erentiated from F6, the F7 of S. masneri is distinctly shorter than F7 of S. lagynos, relative to F6.
Biology and rearing notes.Th e type material of Smicromorpha masneri was obtained by rearing nest pods of Oecophylla smaragdina in a greenhouse where there was no possibility of contamination.Th e weaver ant nest pods were attached to citrus trees obtained from a local nursery.Th ese trees were examined for possible contamination (e.g., scale insects and aphids) prior to use and the ants and their host trees were the only occupants of the greenhouse.Th is confi rms that these wasps are associated with the Oecophylla smaragdina and that in all likelihood these wasps are primary parasitoids of weaver ants.
Two nest pods -arboreal nest fragments made of leaves and held together with silk from the third-instar ant larvae -were collected at Bach Ma National Park on July 27, 2000 and transported by air in double-sealed containers to Toronto, Canada.Th e containers were delivered to Tom Mason and Lydia Attard at the Toronto Zoo on July 1; on arrival one nest pod contained only dead ants and the other was assigned #35747.By July 5 new pods were being constructed by the ants and on August 9 Tom Mason observed and later collected a small insect fl ying in front of one of the new weaver ant pods -the specimen was sent to me for identifi cation.On August 13, three more specimens were caught hovering in the vicinity of the weaver ant pods.Th ese four specimens comprise the type series of S. masneri.Given that the parasitoids were associated with a weaver ant nest in a secure indoor facility and far outside its normal range it is virtually certain that the wasps emerged from the ant nest that was transported to Toronto -and that the type locality is properly indicated as Vietnam.Th e ant colony survived at the Toronto Zoo for almost a year but no additional Smicromorpha were observed.It is curious that no males were collected but males wouldn't necessarily be expected hovering around the weaver ant pods, unless they were searching for mating opportunities.

Discussion
Weaver ants are most vulnerable to predators and parasitoids that are active outside the nest when workers use the fi nal-instar larvae for nest pod construction and repair.Th e larvae are brought outside the nest pod in the mandibles of the workers and moved back and forth while producing silk to fasten the leaves together (Hölldobler and Wilson 1990, Plate 24).In Th ailand, the larvae are rarely used for external weaving during the daytime, but this activity increases at night (Hemmingsen, 1973).Th is helps explain unusual aspects of both the behaviour and morphology of Smicromorpha.Naumann (1986) notes that at least 4 of the 5 previously described species are attracted to light and are probably nocturnal, which is unusual for Chalcidoidea.Many of the distinctive morphological features of these wasps, including the large eyes and ocelli, light non-metallic body color (the so-called "ophionoid facies", Gauld and Huddleston 1976), and extremely slender and apparently mobile gaster, are consistent with a highly specialized nocturnal parasitoid lifestyle.
"talking hyms".In the long term, his greatest legacy will probably be overlooked.In my opinion, this will not be the excellent Hymenoptera collection in the Canadian National Insect Collection in Ottawa, or the specimens of "proctos" he has identifi ed and distributed to many museums worldwide.His legacy will be the specimens of all groups of insects, collected in all parts of the world, by fi eld biologists who have fallen under his spell!Th ese specimens, many of them from habitats that no longer remain in their pristine form, and languishing in freezers and in the deepest reaches of collections, will continue to throw light on the diversity of life on earth for the foreseeable future.Th e discovery of this new species was facilitated in part by a Discover Grant from the Natural Sciences and Engineering Council of Canada (NSERC).Th e impetus to collect the weaver ant colonies came from Tom Mason and Lydia Attard (Toronto Zoo) and the collections were made by Brad Hubley.Antonia Guidotti assisted with the manuscript and the illustrations were prepared by Patrice Stephens-Bourgeault.