Castiarina allensundholmi

As at October 2015, geographically this species is known from only two localities:

(1) Prior to October 2015 only three specimens were known, being the three specimens in the type series found by Alex Scott, Allen Sundholm and Joe Bugeja in October 2003. These were found west of Euabalong West, Lachlan Plains, central New South Wales, Australia.

(2) Twelve years later, in October 2015, Allen Michael Sundholm found two specimens in the Goobang Range, New South Wales. This locality extended the known range of the species 200 km to the east.

The species probably has a larger geographic distribution, but this cannot be confirmed without considerable additional field work. Nevertheless, despite considerable research undertaken by entomological enthusiasts in the areas to the west of the Euabalong West sites since 1980, no further specimens have been found, indicating that the Euabalong West sites (which are ecotonal between mallee habitats to the west and open woodlands to the east) may be at or near the western geographic limit for this species.

The altitude where the three specimens in the type series were found averages 170 m above the 2015 sea level. The altitude of the Goobang Range locality is 565 m above the 2015 sea level.

All five known adult specimens were found during October, from early October to late October.

The occurrence of emerged and active adult specimens at any particular site may vary several weeks earlier or later than typical for that site from one season to the next, due to natural variability in the seasons.

As with most species of Australian Buprestidae, nothing is known of the early stages of this species, including the other two species in the Castiarina balteata species group. Not only are the early stages of Castiarina allensundholmi unknown, but the larval host plant(s) are also unknown, nor how long it takes to complete its life cycle from one generation to the next. The adult host plant at the Euabalong West locality, Micromyrtus sessilis, does not occur at the Goobang Range site, but may occur nearby. The adult hostplant at the Goobang Range site, an undetermined species in Leptospermum, does not occur at or near the Euabalong west site.

Identification of the larval host plant(s) of Castiarina allensundholmi would assist delineating its geographic range and habitat requirements. Identification of the larval host plant(s) of the two other known species in the Castiarina balteata species group may also be of help. However, there are currently no public resources allocated to identifying the larval host plants of any Australian Buprestid species.

The five known (as at October 2015) adult specimens of this species were collected from the flowers of Micromyrtus sessilis (near Euabalong West, NSW) and an unidentified species in Leptospermum (Goobang Range, NSW). As is typical for species in Castiarina, the adults of this species are doubtless nectarivorous, feeding on the nectar of the adult host plants when in peak bloom. They may also feed on the petals.

Environmental factors such as climatic conditions, e.g. drought, or a certain amount of prior rainfall at a certain time of the season, may respectively either inhibit adult emergence or trigger pupation followed by adult emergence.

If the two known (as at October 2015) localities for this species are any guide, then there has been severe loss of this species habitat since human settlement. Continued land clearance in its known range generally, particularly the two known sites, neither of which lies within a nature conservation reserve, would likely be significantly detrimental to its survival.

No studies have been published to assess the impact of climate change on this species nor on any other described or undescribed species in the Australian Buprestid fauna, which comprises at least 1,600 species. However, given the very limited habitat within its known geographic range generally, rapid climate change (e.g. within 10 – 100 years) to a climate beyond the climate variations this species can consistently withstand would likely be significantly detrimental to its survival.