Notes on the biology, distribution, biosecurity status and history in New Zealand of Macrotrachelia nigronitens (Stål, 1860) (Heteroptera: Anthocoridae)

Abstract Macrotrachelia nigronitens (Stål, 1860) (Heteroptera: Anthocoridae) is permanently present in the wild in Auckland (AK), New Zealand. It should therefore be added to the New Zealand Organisms Register (NZOR). It is a specialised predator of thrips inside leaf-roll galls. It has been present in New Zealand since at least the 1980s. Aspects of its biology, distribution, biosecurity status and history in New Zealand are discussed. The first detailed specimen records from New Zealand are provided, and a biological association is noted for the first time with Teuchothrips disjunctus on Callistemon, probably its main association in New Zealand, where only two species of thrips cause leaf-roll galls. It has not been found associated with other thrips in New Zealand. Macrotrachelia nigronitens is not known to be present in Australia, but the poorly known Anthocoris austropiceus Gross, 1954 has been reported, in an easily overlooked publication, to be associated with Teuchothrips disjunctus on Callistemon in Canberra. This led to an early tentative identification, by the author, of New Zealand material of Macrotrachelia nigronitens as Anthocoris austropiceus, in collections. This likely misidentification can now be discounted, but further research in Australia is required to determine the true identity of both Anthocoris austropiceus, and whatever species of anthocorid was found in Canberra.


Introduction
Macrotrachelia nigronitens (Stål, 1860) (see Fig. 1) has recently been reported from New Zealand by Larivière and Larochelle (2014), but with few details. They say only (p. 365) that 'The grey literature suggests that this species is present in New Zealand since at least 2006. This can now be confirmed based on comparison between specimens from NZAC and MACN.' No "grey literature" was specified. Such publication of new records without supporting data is not particularly useful. Consequently, the present author herein takes the opportunity to publish data on this species from material currently accessioned in the collections of the Auckland War Memorial Museum (AMNZ), comprising 11 specimens collected between 1997 and 2014. NZAC also holds material of this species but, unfortunately, this material is now unavailable to the author, despite being responsible for most of it. The proper assessment of the biosecurity status of M. nigronitens in New Zealand, particularly in terms of how long the species has been present here, requires the tracking down and validation of all relevant material in collections, which has not yet been done, despite all the material being very easily located. Investigations by the author suggest that the species has been present in New Zealand since at least the 1980s. An application (see http://www.epa.govt.nz/Publications/proposal_form_macrotrachelia_ spp.pdf) has recently been submitted by Bioforce Limited to the Environmental Protection Authority (EPA) to have M. nigronitens declared as "not new", so that it can be legally propagated and/or distributed for the purposes of biological control of pest thrips. In fact, it shall be argued herein that M. nigronitens ought never to have been classified as a "new organism" (under the Hazardous Substances and New Organisms (HSNO) Act = not present in New Zealand before 29 July 1998) in the first place, had its biosecurity status been properly assessed. An AMNZ record from 1997 is presented, and an even earlier record from the 1980s is indicated to be held in NZAC. Notes are provided on the biology, distribution and history in New Zealand of M. nigronitens.

Distribution
Within New Zealand, Macrotrachelia nigronitens is present in at least the vicinity of Auckland City and suburbs (AK). The genus Macrotrachelia consists of 6 currently recognised Central American species, with only M. nigronitens extending (naturally?) into South America (Argentina, Brazil), and possibly also adventive in California (Carpintero 2002, Lewis et al. 2005.

Biology
Macrotrachelia nigronitens is a predator of thrips inside leaf-roll galls induced by the thrips. Two species of thrips (Thysanoptera: Tubulifera: Phlaeothripidae) are responsible for such galls in New Zealand, both of them adventive. One is Gynaikothrips ficorum on Ficus microcarpa (Moraceae). The other is Teuchothrips disjunctus on Callistemon (Myrtaceae). Ficus microcarpa is rare in New Zealand, present only in cultivation as an ornamental. Callistemon is far more common, and probably represents the main habitat of M. nigronitens in New Zealand. Note that Gynaikothrips ficorum in New Zealand appears to occur only on Ficus microcarpa, and not any of the other, more common species of Ficus. Note also that M. nigronitens has not been found feeding on any other thrips, at least not in New Zealand.
The data presented herein strongly indicates that Macrotrachelia nigronitens is present in New Zealand as a permanent wild population in suburban gardens and parks. It should therefore be added to the New Zealand Organisms Register (NZOR), as exotic and present in the wild.
The pathway of entry of Macrotrachelia nigronitens into New Zealand is unknown. It may have arrived here directly from the Americas, associated with Gynaikothrips ficorum, and then shifted host to the much more locally abundant Teuchothrips disjunctus on Callistemon. It is not known to be present in Australia, where both Teuchothrips disjunctus and Callistemon are native.

Discussion
In about 2004, the author noticed an unidentified anthocorid specimen in the collection of Auckland Museum (AMNZ 59842), which was collected in the Auckland suburb of Henderson in 1997. Subsequently, Dr. Jocelyn Berry (then hymenopterist at NZAC) gave the author some material collected from Auckland Regional Botanic Gardens in August 2005, and given to her privately by the collector. This material was associated with thrips ( Teuchothrips disjunctus) in leaf-roll galls on Callistemon sp. The species was subsequently found by the author in the same habitat in Auckland Domain. In the then absence of a clue to the identity of the species, the author noticed a published reference by Mound and Walker 1986 to Anthocoris austropiceus Gross, 1954. It had been found in leaf-rolls of Teuchothrips disjunctus on Callistemon, in Canberra, Australia (see p. 83.) The author tentatively identified the New Zealand species as A. austropiceus, based purely on the biological association. The identity of A. austropiceus remains somewhat unclear from the original description in Gross 1954. The Canberra material could not be located, and the (presumably) unique female holotype of A. austropiceus (AMSA K.67861) is apparently mounted on a microscope slide (see http://collections.australianmuseum.net.au/amweb/ pages/am/Display.php?irn=1564065), and has not been examined by the author. M. nigronitens has not been reported from Australia. Therefore, Australian entomologists are encouraged to double check the true identities of both Anthocoris austropiceus Gross, 1954, and whatever species of anthocorid was collected in Canberra (the basis for the identification of the latter as A. austropiceus is unknown, and therefore misidentification cannot at present be ruled out), as it is not impossible that one or other of them could turn out to be M. nigronitens. Note that Anthocoris austropiceus is the only known native Australian member of the tribe Anthocorini (see http://www.environment.gov.au/biodiversity/ abrs/online-resources/fauna/afd/taxa/ANTHOCORINI/checklist), the tribe to which Macrotrachelia is also assigned (Carpintero 2002). It therefore appears to be somewhat discordant with the remaining native Australian anthocorid fauna.
research entomologist) suggesting that the imaged specimen was in fact a species of Macrotrachelia, which he suggested was probably M. nigronitens, but with some reservations as the genus has not been taxonomically revised in recent times. Meanwhile, the author noted a specimen in NZAC collected in the 1980s ( David Horton initially intended to publish the New Zealand record of M. nigronitens, but it was apparently subsequently decided, after some correspondence with New Zealand entomologists, that the matter would be best left to them (D. Horton, pers. comm.) Note that the present author had already sent New Zealand material to Horton, who carefully examined it, including dissections of both male and female genitalia, and he determined it as Macrotrachelia nigronitens, based on the published literature. Larivière and Larochelle 2014 formally published the identification after 'comparison between specimens from NZAC and MACN', but without giving details how the comparison was made, or upon what the identification of the MACN material is based. Nevertheless, the present author accepts the determination as being certain enough to run with, in lieu of future taxonomic and/or molecular studies.