A new species, family, and suborder of beetle for Aotearoa New Zealand – Distocupes varians (Lea, 1902) (Coleoptera: Archostemata: Cupedidae)

ABSTRACT

Distocupes varians (Lea, 1908) (Coleoptera: Cupedidae) is a species within the relictual suborder Archostemata. This suborder has a nearly worldwide distribution, which includes the Gondwanan regions and countries Australia, New Caledonia, southern South America, but not New Zealand. The larvae of Archostemata are woodborers, with several cupedid species known to feed on fungi-rich rotting wood, whereas the adults feed on pollen or sap. Until recently, these beetles were unknown from New Zealand, but in November 2021 two adult specimens were caught in SLAM traps in Laingholm, West Auckland. These specimens were collected two weeks apart, which suggests that there is an established population, rather than these being independent incidents of wind-assisted arrivals. This hypothesis is further corroborated by additional specimens of D. varians collected or photographed during November and December 2022, which were then recorded on iNaturalist (https://inaturalist.nz/), a citizen science platform to record, organise and identify biodiversity.

KEYWORDS:

• Australian beetles
• Gondwanan
• reticulated beetles
• SLAM traps
• wood-boring larvae

Introduction

Coleoptera is the most diverse insect order worldwide, with species divided into four suborders: Archostemata Kolbe, 1908, Adephaga Schellenberg, 1806, and including Hydradephaga (e.g. Dytiscidae) and Geadephaga (e.g. Carabidae) as per McKenna et al. (2015), Myxophaga Crowson (1955) and Polyphaga Emery, 1886 (Caterino et al. 2002; Maddison et al. 2009). Almost all (99%) of coleopteran species can be found within the sister groups of Adephaga and the hyper-diverse Polyphaga (Caterino et al. 2002), with only a small number of extant species in the relictual suborders Archostemata and Myxophaga. In Aotearoa New Zealand, the 4700 + described native beetle species are found within the two suborders Adephaga and Polyphaga (Watt 1981/1982; Leschen et al. 2003) and until now, there have been no recorded species of Archostemata in New Zealand, either extant or fossil.

Species of Archostemata appear in the fossil record ∼240 million years ago (McKenna et al. 2015). This suborder comprises 40 extant species in five families: Crowsoniellidae (monotypic), Cupedidae (31 spp.), Jurodidae (monotypic), Micromalthidae (monotypic) and Ommatidae (six spp.) (Kirejtshuk et al. 2016; Lawrence & Escalona 2019). There are many Archostemata in the fossil record from the Permian era including nine families, 74 genera and 186 species, with this suborder sharing some primitive morphological and biological characteristics with the extinct Protocoleoptera (McKenna et al. 2015; Hörnschemeyer 2016).

The most diverse family in Archostemata, Cupedidae Laporte (1836), with 31 species in nine genera, has a near worldwide distribution. This family includes two Australian endemic genera (Adinolepis Neboiss 1984 and Distocupes Neboiss 1984), with a total of five species, plus two endemic New Caledonia species within the genus Ascioplaga Neboiss 1984 (Kirejtshuk et al. 2016). Australia also has two genera and five species in the family Ommatidae (Hörnschemeyer & Beutel 2016), which is often referred to as a subfamily within Cupedidae but is clearly well supported as a monophyletic family by McKenna et al. (2015).

Cupedidae adults generally have narrow, elongated, dorsoventrally flattened bodies ranging in length from 5 to 25 mm (Figures 1–3). They most likely feed on pollen or sap (Neboiss 1984; Hörnschemeyer & Yavorskaya 2016; Kirejtshuk et al. 2016). In Australia, the adults have mostly been collected during the austral spring/summer months of November to March but are not recorded in large numbers (Atlas of Living Australia 2022). A common name used for cupedids is reticulated beetles, which is derived from the incomplete sclerotisation of the elytra seen in the adults (Figure 1). Only the longitudinal veins and numerous cross veins are sclerotised, while the interstices retain the transparent wing membrane giving the elytra a window-like look or reticulation (Figure 2) (Neboiss 1984; Hörnschemeyer & Yavorskaya 2016).

Figure 1. Dorsal habitus of Distocupes varians (Archostemata: Cupedidae), caught with a sea, land, air, Malaise (SLAM) trap in Laingholm, Auckland (November 2021). Manaaki Whenua – Landcare Research specimen number: NZAC04217627. Scale bar = 1.00 mm. [Photograph by Leanne Elder, Manaaki Whenua – Landcare Research.]

Figure 2. Distocupes varians elytra (A) with the sclerotised longitudinal veins and a detail (B) of the non-sclerotised interstices between the longitudinal veins. The detail (B) is indicated by the grey hash-lined rectangle over the right-wing case (A). Scale bar = 1.95 mm. [Photograph by Author.]

Figure 3. Distocupes varians dorsal (A) and ventral (B) views of the head and pronotum, with detail of the relatively large eyes, narrow head and pronotum. Scale bar = 1.57 mm. [Photograph by Author.]

Cupedidae larvae are woodborers that feed on fungi-rich rotting wood (Young 2001; Lawrence & Escalona 2019) and have been found in some construction materials (Neboiss 1968; Young 2001), including structural timbers in Australia. Most larvae are between 15 and 38 mm long, subcylindrical in shape and parallel sided, and are similar in appearance among the species (Hörnschemeyer & Yavorskaya 2016).

Methods

During November/early December 2021 (extended Auckland COVID 19 lockdown), I set a SLAM (Sea, Land, Air, Malaise) trap (purchased from Australian Entomological Supplies, NSW) in my semi-rural garden (Figure 4) in Laingholm, West Auckland (S36°58'03", E174°38'28"). The property has a very large puriri (Vitex lucens) tree with fallen wood debris, as well as continuous vegetation verges (two to six metres wide) of mostly native shrub and tree species, including kanuka (Kunzea robusta), red matipo (Myrsine australis), kauri (Agathis australis), totara (Podocarpus totara), kawakawa (Piper excelsum), pohutukawa (Metrosideros excelsa), kowhai (Sophora sp.), taraire (Beilschmiedia tarairi), ngaio (Myoporum laetum), Coprosma spp., mahoe (Melicytus ramiflorus), nikau (Rhopalostylis sapida), flax (Phormium tenax) and cabbage trees (Cordyline australis), that provide a constant supply of flowers/fruit/sap throughout the austral spring, summer and autumn.

Figure 4. The position of the Sea, Land, Air, Malaise (SLAM) trap in a semi-rural garden, Laingholm, Auckland, New Zealand. The top of the trap was set approximately two metres off the ground and was collecting invertebrates from early November to early December 2021.

A SLAM trap is a versatile trap combining the design of a Malaise, flight intercept and an emergence trap (terrestrial and aquatic), but the dimensions are generally smaller (110 cm × 110 cm × 110 cm) so fewer specimens are collected. This trap can be deployed in several ways to capture a variety of different insects, including free standing, floating on water, or suspended at different heights (e.g. Figure 4). An additional net can be attached that is suspended underneath to catch flying insects that drop when encountering an obstacle. However, I did not attach this additional net due to the large quantities of fine kanuka leaf material that can block the top of the collection pottle.

iNaturalist is a citizen science platform to record, organise and identify biodiversity in all ecosystems, whether on a local, regional, national, or global scale (Mesaglio & Callaghan 2021). The first Distocupes varians observation from New Zealand was recorded on iNaturalist on the 18th of November 2021 (Table 1).

Table 1. iNaturalist records of Distocupes varians (Cupedidae) collected or photographed in the suburbs of West Auckland, New Zealand, in 2021 and 2022.

Number of specimens	Locality and date	Collection	iNaturalist Link
1	Victory Road, Laingholm; semi-rural garden. 12–19 Nov 2021	New Zealand Arthropod Collection (NZAC), Auckland	https://inaturalist.nz/observations/101505953 S36°58'03" E174°38'28"
1	Victory Road, Laingholm; semi-rural garden. 26 Nov–03 Dec 2021	David Seldon Collection, Auckland	https://inaturalist.nz/observations/102381131 S36°58'03" E174°38'28"
1	Glen Eden; border of garden/native bush. 26 Nov 2022	Private Collection, Auckland	https://inaturalist.nz/observations/143128942 S36°91'58" E174°38'84"
1	Titirangi Road, New Lynn; on wall at night, attracted to light. 30 Nov 2022	Private Collection, Auckland	https://inaturalist.nz/observations/143300547 S36°91'82" E174°63'32"
1	Titirangi/Glen Eden border; on wall at night, attracted to light. 27 Dec 2022	Photograph only	https://inaturalist.nz/observations/145222536 S36°92'47" E174°64'54"

Results

When the photograph of the first Distocupes varians specimen (Table 1) was uploaded to iNaturalist, Samuel Brown (a Plant & Food Research entomologist) alerted me to the significance of this beetle species as a new record for New Zealand of the suborder Archostemata. Subsequently Alan Flynn, Biosecurity New Zealand (Ministry of Primary Industries), collected the specimen for identification from the author.

The initial specimen of Cupedidae (Archostemata) was identified as Distocupes varians (Lea 1902), by R.A.B. Leschen (Coleoptera expert), New Zealand Arthropod Collection, Manaaki Whenua – Landcare Research and then verified by B.P. Boyd, Biosecurity New Zealand (MPI). Information regarding the first Distocupes varians specimen identified as a new beetle incursion into New Zealand can be accessed on the NZAC database: https://scd.landcareresearch.co.nz/Specimen/NZAC04217627.

In 2021, two specimens were caught two weeks apart during November (Table 1), and even though the SLAM trap was left in situ until the end of January 2022, no more specimens were captured.

The first two specimens recorded were collected in Laingholm from SLAM trap samples by the author, whose iNaturalist name is ‘@carabidave’, in late 2021. The third and fourth specimens were collected by hand in late November 2022 and the photographs uploaded to iNaturalist by @invertebratist in the Titirangi/Glen Eden border (Figure 4). The fifth specimen was photographed in late December 2022 in the same general locality as the previous two specimens and uploaded by @greg_holwell. These specimens were caught or photographed in semi-rural gardens, near native bush in the foothills of the Waitakere Ranges (Figure 5).

Figure 5. The localities (red marker points) of the Distocupes varians specimens collected or photographed in West Auckland, New Zealand in 2021 and 2022 in Table 1. [Map sourced from iNaturalist.]

Discussion

Distocupes varians (Cupedidae), the only species represented in the monotypic genus Distocupes, is present in eastern Australia and Tasmania (Hörnschmeyer & Yavorskaya 2016; Lawrence & Escalona 2019) and it is most likely that the Auckland population originated from one of those areas. Specimens of Distocupes can be easily distinguished from all other Aotearoa New Zealand Coleoptera by the incomplete sclerotisation of the adult elytra (Figure 1). The transparent membrane interstices and the sclerotised longitudinal veins give the elytra window-like look, or reticulation (Figures 1–3), that is not a character of any New Zealand beetle species.

Because the two specimens initially collected in New Zealand were captured two weeks apart (Table 1), it has been proposed by Biosecurity New Zealand (B. P. Boyd pers. comm.) that D. varians had established somewhere in the Laingholm area, rather than being a wind-assisted incursion of individuals from Australia. Furthermore, the collection/observation of specimens in other western suburbs in 2022 gives strong evidence to support the presence of an established population of D. varians in Auckland. In Australia, the adults of this species are active from August to March (Atlas of Living Australia 2022). However, in Auckland the adults have only been observed or collected over a shorter period, i.e. November to December (Table 1).

There is little known about the larvae of most Cupedidae species, but in Australia they have been found in rotten pine logs and some building materials (Neboiss 1968; Lawrence 1987). Additionally, larvae of D. varians (Australia) have been found in partially decayed Norway spruce (Picea abies) (Neboiss 1968; Lawrence 1987), as well as some structural material. Neboiss (1968) noted that the infested P. abies wood was in contact with the ground, indicating a high moisture content was required for attack. He also commented that the feeding galleries followed the wood grain and avoided the harder autumn wood (Neboiss 1968). The larvae of D. varians are typical of all Cupedidae larvae in that they are a whitish colour, elongate, sub-cylindrical, parallel-sided, and with a slightly sclerotised head (Neboiss 1968, 1984). Pupation takes place within galleries in the rotting wood (Neboiss 1968; Hörnschemeyer & Yavorskaya 2016). Therefore, it is likely that this beetle species will be able to inhabit a variety of softwood tree species (e.g. Pinus) in New Zealand.

Even though D. varians larvae are wood-boring and have been found associated with timber building materials (Neboiss 1968; Lawrence & Escalona 2019), MPI Biosecurity New Zealand has determined that this species poses little threat to New Zealand’s construction and forestry industries (B. P. Boyd pers. comm.). Not much is known about the biology or ecology of the Australian cupedids as they have never been found or observed in large numbers (Atlas of Living Australia 2022). However, in New Zealand D varians has been collected at night when attracted to external house lights, resting on tree bark at night and by SLAM trap (Table 1). Distocupes varians is found in the eastern regions of Australia, including Tasmania (Atlas of Living Australia 2022), and it is assumed that this species will establish a similar ecology-limited distribution in New Zealand.

Acknowledgements

I would like to thank Samuel Brown (Plant & Food Research) for his initial identification to suborder of D. varians on iNaturalist and imparting the significance of the find to me. I acknowledge the important role of iNaturalist as a platform for identification and biodiversity records. Thanks go to Richard Leschen for identifying the specimen to species and encouraging me to publish. I thank the MPI Biosecurity staff Alan Flynn for coming onsite, collecting the first specimen (during COVID lockdown), and Ben Boyd for confirming the specimen’s identity. The photograph of the specimen for Figure 1 was taken by Leanne Elder (Manaaki Whenua – Landcare Research) and is greatly appreciated. Thanks to Thomas Buckley and Rich Leschen (Manaaki Whenua – Landcare Research) for comments on the initial draft.

Disclosure statement

No potential conflict of interest was reported by the author.