Tuesday, 2 September 2014

A Small Mystery Solved

By the way, Spring is springing and it is good to see some regulars back in the blog business (see Snail's blog noted to the left of this offering).

A trip out Dimbulah way seemed slightly less than successful the other night until a I took a closer look at three tiny black and white cockroaches that appeared at the light sheet.

It seems they are the second known representatives of what was described as Ectoneura hanitschi (Burmeister). The type was photographed and appears on p. 250 of the cockroach guide. It is a small species measuring only about 5 mm it was attracted to Blacklight on a cool and windy night.

This lovely photo by Buck Richardson does not portray the dry, dusty and rather miserable habitat of the foreground. The light sheets were positioned not far from this "idyllic" setting. Trees included several eucalypts, Acacia, Grevillea and several small shrubs. The understory was largely grass, Speargrass, Heteropogon contortus, and Kangaroo Grass, Themeda. There were termite mounds close by and these may harbour this cockroach. But with 3 specimens showing up at light, the cockroaches could spend the day under loose bark or in leaf litter or elsewhere, who knows?

A few words about "hanitschi". This species was described from Burnside, Northern Territory. This locality is hundreds of kilometres from the Dimbulah site. Burnside is probably in the vicinity of what is now Marrakai, NT. We are a bit unsure of the precise location at this point. The original specimen was collected by Edward Handschin many years ago and described by Princis in 1965 as a "replacement" name for a taxon described by Richard Hanitsch in 1934.

The Burnside habitat is probably ecologically similar to the site near Dimbulah. In fact, several katydids reflect a broad distribution across the Top End of Australia. They include Conocephalus upoluensis (Karny), Nicsara bifasciata (Redtenbacher) and Chlorobalius leucoviridis Tepper just to name a few. So it is not entirely surprising to find an insect from two such widely separated localities. It seems quite possible that this cockroach will be found at locales between the two places should someone care to look.

Based on the specimens found near Dimbulah, this cockroach is misplaced in the genus Ectoneura. It is more appropriately ascribed to the related genus Choristima based on the presence of a single apical spine on the fore femur and the minute punctures on the pronotum. Chortistimas are typically more robust than most Ectoneura cockroaches.

Seems like an unduly amount of verbiage for a few little cockroaches. But there is a story for all creatures large and small!

Rentz, D. 2014. A Guide to the Cockroaches of Australia. CSIRO Publishing 318 pp.