BunyipCo: Search results for Ellipsidion

Showing posts sorted by relevance for query Ellipsidion. Sort by date Show all posts

Tuesday, 2 February 2021

Incredible!

Allen Sundholm conveyed this image of a Jewel Beetle Castiarina maculicollis found by Robert Richardson near Goonoo Goonoo, New South Wales.

Castiarina mculicollis A. Sundholm photo

This beetle appears to be a classic example of Mullerian Mimicry. The beetle resembles at least three species of diurnal cockroaches in the genus Ellipsidion. The geographic range of the beetle coincides with that of the cockroaches.

Ellipsidions are cockroaches that look like anything but cockroaches. They are gaudy, brightly coloured and active mostly during the day. Their bright colours and patterns stand out. They can frequently be found on flowering plants such as Eucalyptus, Acacia or smaller shrubs and forbs. The beetle is also active during the day and Jewel Beetles frequently found on flowers.

The cockroaches mingle with the bees, wasps, beetles and other insects that visit the flowers. Insects with bright orange colours, such as those found in coccinellid beetles (lady beetles), cantharid beetles some flies and a host of moths are avoided by vertebrate predators such as lizards and birds. Chemicals incorporated in the bodies of these insects render them toxic. Young birds quickly learn to avoid lady beetles, for example, after their first encounter.

The Castiarina beetle seems to be uncommon (personal suggestion by A. Sundholm). This is one of the defining features of a Mullerian Mimicry system. That is, several members are toxic and a few others are not toxic but present in numbers much less than those of the others. If the non-toxic examples became more common than those that are toxic, the scheme would not work.

Of course, the geographic ranges of model and mimic have to overlap at some stage otherwise what is the point? In the case of the Castiarina beetle, it has been found in inland New South Wales, the Australian Capital Territory and Queensland. One of the Ellipsidion cockroaches, the Western Ellipsidion, E. australe Saussure has a fairly broad range extending across the top of Australia from the Northern Territory across to Cape York, central and southern Queensland, New South Wales and Victoria Rentz, 2014. Therefore, several of these cockroaches overlap in their distributions with that of the beetle.

Here are some examples of the cockroaches:

Ellipsidion australe Saussure

This species seems the closest match to the beetle. Note the dark legs and the antennae, the latter of which are black to the tip. C. Rowan photo

This is the Beautiful Ellipsidion Ellipsidion simulans Hebard. Note the antennae that are lighter towards the tip. This apparently gives the allusion that the antennae are shorter than they really are. The yellow cerci and reddish legs are not shared with the beetle.

Common Ellipsidion Ellipsidion humerale Hebard, or, perhaps, an undescribed species. This cockroach has the more pronounced difference in the antennae but lacks the dark spot present in the centre of the thorax found on the beetle and other roaches. The yellowish cerci are not shared by the beetle. D. Knowles photo

Tableland Ellipsidion Ellipsidion gemmiculum Hebard is a small species, often found in numbers feeding on grass seed heads during the day in full sunlight. It has few characters shared with the beetle.

To a vertebrate predator on the move the range of colours and patterns in Ellipsidion might just be a reinforcement to move on and avoid these orange critters, large and tempting that they may be but they could result in an unpleasant episode.

Thanks to Allen Sundholm and Robert Richardson and D. Knowles and C. Rowan for the photos which can also be seen in the Cockroach Guidebook.

Literature

Rentz, DCF 2014. A Guide to the Cockroaches of Australia. CSIRO Publications, Pp. 1-318, Collingwoood, Vic.,

Friday, 13 February 2015

Who Said Cockroaches Are Not Colourful!

On a recent trip with some James Cook University students, a few remarked that they had no idea tht cockroaches could be so colourful.

Well here are a few examples that will hopefully challenge your perception of these insects as being rather dull creatures that often invade human habitation. The fact is that most species have little to do with humanity and could not survive long in our homes, restaurants, hotels etc. We just don't
"offer" what they are looking for!

This one, the Inland Ellipsidion, Ellipsidion amplum Hebard literally flew into me while I was walking on a Cairns street in the centre of town. It is a diurnal species that lives on flowers where it feeds on pollen and nectar. The bright orange colour pattern suggests Mullerian Mimicry.

The Inland Ellipsidion Ellipsidion amplum Hebard, dorsal and ventral views.

Ellipsidon cockroaches are fairly common across the continent where they have a rather similar appearance. This is among the largest of species measuring 17 mm.

The above-noted specimen was a bit battered after being carried around in a shopping bag for a few hours. Here is an example of the species in much better condition. Note the orange-tipped antennae. Other species have the antennae with white tips. In addition, the antennae are very hairy (click on the photo to enlarge), a condition quite unusual in most Australian cockroaches.

Ellipsidion is a member of the large family Ectobiidae (formerly Blattellidae) and is in the subfamily Pseudophyllodromiinae. This is quite a mouthful. However, species in this subfamily are usually very attractive. Here are a few examples.

The Australian Allacta, Allacta australiensis Roth.

This species lives in rainforests where it can be found only on tree trunks. It seems to prefer certain trees and not others. It measures 11 mm and is active at night.

The Variable False Pseudobalta, Pseudobalta cinctella (Hebard)

Pseudobaltas are tropical cockroaches that are active at night. They have been found under bark during the day. The species has a broad distribution across the continent and the markings on the thorax (pronotum) are variable. It is small, measuring about 6 mm in length.

The genus Balta includes some 39 described species in Australia. There are many undescribed species, like the one above. Baltas are distinguished on the basis of colour and morphological structures. They are nocturnal and live in leaf litter during the day. Their numbers are often great and they probably serve as food for many other organisms. All known species are active after dark.

The Pretty Balta, Balta verticalis Hebard.

This Balta is aptly named. The specific name refers to the stripes between the eyes. It is a fairly common tropical species in northeast Australia where it can be found in rainforests and along rainforest margins. It measures about 12 mm in length.

The Grey Balta, Balta scripta (Shelford)

One of the commonest Baltas in the northern Tropics, this species spends the day in leaf litter and is active at night. It frequently comes to lights. The pattern on the pronotum and greyish colour is very characteristic.

The Small Mediastinia, Mediastinia australica (Shelford)

Mediastinias are more common than previously thought. They are very small, measuring less than 5mm in total body length. They are very colourful and have a very flattened appearance. This facilitates diurnal life in leaf axils and unfurling leaves. After dark they emerge to feed on particulate matter found on leaf surfaces.

The variable Speedy Cockroach, Choristima bimaculata Roth

This cockroach is another nocturnal species but it belongs to another ectobiid subfamily, the Ectobiinae. Seldom seen during the day, adults can be attracted to light late in the evening. This species has a number of different morphs based on the pattern of the pronotum and wings. They are small, measuring less than 5 mm in total length.

Sloane's Northern Wingless Cockroach, Cosmozosteria sloanei Shaw.

This is an example of the most characteristic group of Australian Cockroaches, the subfamily Polyzosteriinae of the Blattidae. Everyone who has wandered around in the outback or the mixed woodlands of the tropics has come across these large cockroaches abroad during the day. They are very conspicuous in their colour patterns and they seem to be walking bags of nasty chemicals. They are avoided by birds and lizards. This one is about the size of a 20 cent Australian coin.

But these insects are the topic of a future blog.

Thursday, 2 February 2012

Cockroaches By Any Other Name.........

I am writing a Guidebook to Australian Cockroaches for the Guidebook series published by CSIRO, Australia. For the past couple of years I have been taking many trips into the bush for the purpose of adding to the photographic content of the book. A recent trip to The Lynd in south central Queensland proved a bonanza for the cockroach enthusiast. But even this is a bit much.

Hundreds of primarily a single species congregated on the light sheet, apparently encouraged by the pheromones left by their "colleagues". What you see here is primarily two species. The blackish blattodeans are females of an undescribed species Parasigmoidella. The males are the ones with the tawny wings.

There are at least two other species in the photo. They are both in the genus Johnrehnia. They can be distinguished by the light yellow column on the pronotum (a part of the thorax) bounded by wavy black stripes. Not so pretty but the others that accompanied them were very attractive anyway you look at them.

Balta sp., probably yorkensis Hebard (Ectobiidae; Pseudophyllodromiinae)

Balta godeffroyi (Shelford) (Ectobiidae; Pseudophyllodromiinae)

Ectoneura pallidula Hebard (Ectobiidae; Ectobiinae)

Choristima bimaculata Roth (Ectobiidae; Ectobiinae)

Ectoneura minima (Tepper) (Ectobiidae; Ectobiinae)

Ellipsidion sp. (Ectobiidae; Pseudophyllodromiinae)

Ellipsidion humerale (Tepper) (Ectobiidae; Pseudophyllodromiinae)

Escala vestjensi Roth (Ectobiidae; Blsttellinae)

One seldom encounters native cockroaches by day. Many live in leaf litter where they are probably important decomposers, turning the litter into soil. The numbers of species, adults and nymphs in a square metre of leaf litter in the rainforest or eucalyptus woodland attests to how important these insects must be in the health of the bush. But for the most part, we really have no idea where these roaches are during the day. Some probably live under bark or in bark cracks, others in unfolding leaves.

The Ellipsidion species are a bit unusual in that they are diurnal in their activities. The often can be found on flowers of grasses and other flowering plants where they feed on the pollen and developing seeds. They surely must play some role in pollination. Many are brightly coloured and avoided buy birds and lizards.