Sunday, 14 December 2014

The Complexities of Cockroach Systematics

Australia must be the centre of diversity for the cockroaches. It seems more species occur here than any other known place. More than 500 species have been described and it is estimated that half again that number await discovery and description. Just on this 1.6A site of regenerated rainforest here in Kuranda, I have recorded more than 90 species.
This bar graph shows the distribution of families against the number of species discovered. The Ectobiidae (formerly the Blattellidae) have more than seven times the next family (Blaberidae) represented.Within the Ectobiidae, there is a a rather balanced representation of subfamilies known for Australia.

The purpose of this blog is to relate some of the complex problems that a taxonomist faces when working in this ancient group of insects.

Cockroaches have been around for a long time. Fossil evidence suggests that cockroaches 200 million years ago looked pretty much as they do today. Being generalised feeders rather than specialised ones, they can find what they need most of the time. As a result they have occupied many and varied habitats. Within Australia, they can be found almost anywhere from the mountain tops, deserts and coastal islands. A few seem to be subaquatic.

Most entomologists who study cockroaches do so from collections in the great museums of the world. Some have never seen a cockroach in nature, except for some of the 6-8 species that exist in the kitchens and dwellings of humanity. These few domestic species have given the entire group a bad name. But the thousands of species that occupy natural habitats are interesting and their biologies varied.


Louis M. Roth photo: P. Naskrecki

Lou Roth spent a lifetime studying cockroaches. He probably named more species than anyone else. He had a "worldwide" view of cockroach systematics. That means that he knew whether genera were confined to rather restricted localities or covered vast expanses of territory that might include several continents.

In the end this may have contributed to a dilemma. Dr Roth spent many of his last years working on the Australian fauna. The reasons were simple: Australia has a varied and complex diversity of species and there was money around to help pay for the illustration and publication of his results. [He was active in the 70's and 80's when the Australian Biological Resources Survey was well funded and well-regarded by thoughtful governments concerned about the Australian biota.]

Lou published many generic revisions. His last had to do with cockroaches in the ectobiid subfamily Blattellinae. Several genera are worthy of attention here. They illustrate the complex nature of our fauna and the tough taxonomic decisions that await cockroach-ologists!

Three genera seemed to perplex Lou. They are Carbrunneria, Johnrehnia and Beybienkoa. [These are all named after famous cockroachologists, but that's another story.] Basically the three genera are distinctive in the following way:

"specialised" here means bearing a glandular opening or a patch of hairs.

Carbrunneria; In males first abdominal tergite (the dorsal part of the abdomen) not specialised; seventh tergite specialised;

Beybienkoa; In males the first abdominal tergite is specialised; seventh tergite not specialised;

Johnrehnia; There are no modifications on the tergites of males at all.

In compiling details heading towards the publication of this book,
I discovered some problems that suggest that the above genera need a bit of reorganisation. Perhaps, there are more genera that at first expected. All seem to occur in Australia and a few extend into New Guinea. All are nocturnal and live in leaf litter or under bark by day, and emerge after dark to feed.

At any given locality, all three genera may be encountered and one can frequently find more than one species in a given genus.

Let's examine two species in the genus Johnrehnia, found recently in mixed open forest north of Mareeba, Queensland. These species illustrate the extreme differences in appearance of Johnrehnia species as they are presently understood. Remember their distinguishing feature is that the males have no glandular openings on the dorsal abdominal tergites. Both species are undescribed and both very common.

This dark motif is present on may Australian species. Males can be told at a glance by the tawny colour of the wings.


 Females are uniformly black on top.

With cockroaches, especially the species in the Blattellinae, the male subgenital plate is differentiated and species' distinctive.

 Here we see the tip of the male's abdomen upside down. So his right is to the left. We an see two "styles". These are peg-like sensory devices that are on the margin of the subgenital plate. Taxonomists look at these structures first because they are distinctive and do not vary much form one individual to another.

In many cockroaches, especially the Blattellinae, the male genitalia are not bilaterally symmetrical. This just means that the right side is different from the left. The styles are a good example.
This is the dorsal view of the male showing the tenth tergite (the last body segment) and the subgenital plate with the highly modified, spiny right style and the more or less "normal" left style.

The elongate slender structures are bits and pieces of the concealed genitalia which are located under the subgenital plate and within the end of the abdomen.


Let's look at another Johnrehnia species found at the same locality on the same night.
This species of Johnrehnia, like the one above, has many examples that look just like this-golden colour, distinctive thorax (pronotum) yellow legs and head with a black band across the top and the face with a distinctive number of spots or bars.

Head of above species.
 Dorsal view of the male abdomen. This shows a pair of projections separated by a flexible tongue. Structures can be present or absent and varies in shape and direction depending upon the species. The surface is so colourless that you can see through it to the concealed genitalia within the abdomen.

Here we see the tip of the abdomen on end with the subgenital plate with a greatly modified, hook-like right style and the small left style which is "somewhat" modified.


The male subgenital plate removed. Ventral view showing a bit of the right style and most of the smaller left style.
An end on view of the male subgenital plate. The shape of the hook-like right style is very distinctive of this species. Others have it shorter and with a different base or twisted in a different direction.

What is the purpose, if any, of these outlandish modifications. There is an old "theory" called the "lock and key theory" which suggests that the structures borne by the male can only fit into specifically modified pockets within the abdomen of the female. This is said to maintain species' integrity. With many species of a given genus often present at any given locality, this could act to help prevent hybridisation. Cockroaches probably use chemicals to initially distinguish one another. The glands on the back of other genera probably produce substances that are very species distinctive.

But to conclude this story. It seems that the some of the above very different-looking kinds of Johnrehnia may not be Johnrehnia at all. Some of the species with the "golden appearance" have very faint traces of glandular openings on the seventh tergite. This would point them in the direction of Carbrunneria. 

And it seems that was what Lou Roth was thinking just prior to his death. We have discovered a number of species of the "golden morphs" labelled by Lou as various species of Carbrunneria. Many were previously described species of Johnrehnia. But we could find no written manuscript of Lou's discussing this switch in his thinking and so it will be left to others to sort out this problem.

In the meantime, we continue collecting examples from as many localities as possible to build up the stockpile of evidence so that any changes can be based on an abundance of evidence. DNA sampling can certainly help here.




Sunday, 7 December 2014

Just Like Clockwork

Each year in mid September, on a cold spring night, the Northern Green Grocer Cicada, Cyclochila virens, begins its curious serenade.

The co-ordinated cacophony begins after dark around 6.40 pm. The area pulsates with the calls of the males of the species for about 13 minutes each night. Then quiet.

This odd behaviour continues but it starts a few seconds later night after night. As at the 23rd of November, it started at 6.54 pm. Adding to the peculiarity of this symphony is that it seems geographically co-ordinated. Whether on the Atherton Tableland, the slopes of Mt Lewis, or here in Kuranda, the cicadas start calling at the same time each night. I am uncertain if it is the same individual cicadas that are singing over the course of the species' activity. This seems unlikely.

The Northern Green Grocer is a large cicada. An average male measures about 70mm in length from head to the tip of the wings. They seem to inhabit rainforest trees well off the ground.

When handled an individual will buzz and vibrate. But that does not seem to affect the behaviour of certain predatory birds. Distressed cicadas can often be seen in the grasp of Black Butcherbirds and Spangled Drongos.

I will attempt to monitor these cicadas and determine the finale of their symphony.

A Bit of Sad News



This year's chick is past history. About 2 weeks ago, the male showed up without the bub. He has wandered in several times since, each visit without his youngster.

What could have happened to this little fellow? Well it could have been taken by a predator. These include large goanna lizards, feral cats, dogs, snakes like pythons, or owls and hawks. Or it could have been the victim of an accident. Falling branches and limbs are a constant hazard in the rainforest. I was almost hit the other day by a big branch that crashed down under the weight of  its developing fruit. I was surprised at how quickly it all happened. No chance of stepping aside to avoid it. Or the chick could have been hit by a car. The latter seems unlikely as its body would have been seen by locals- unless it was removed by an embarrassed motorist.

Neighbours have seen the pair of cassowaries courting since the bub disappeared. Whether the male will attempt to bring up another clutch of young remains to be seen. We have not experienced his fatherhood with youngsters this late in the season.

Our area seems saturated with cassowaries. They have large home ranges and do not tolerate intruders even if they are their own kin. Once the chicks have fledged, that is it. They get driven out of each successive territory and end up at the extremes of favourable habitats. It is said that they eventually perish at the margins due to the potential hazards noted above or they simply starve because their specialised foods are not available.

Life is tough.

Sunday, 12 October 2014

He's Back!

We have been worried about Mr Cassowary. It has not been a good year for cassowaries around here. One of the new females was hit and killed by a car on Black Mountain Road a couple of months ago. We have seen the original Mrs Cassowary on a number of occasions. And we had heard that Mr Cassowary had two chicks this year some weeks ago. But we had not seen them. This did not worry us too much as logging and council trucks have been routinely using Black Mountain Road for over a year and it would be very dangerous for an adult cassowary to cross with one of more little chicks.

Well late on Sunday afternoon he appeared with one small chick. One is better than none!


there are lots of potential obstacles for this little fellow, especially this year. It is spring and hungry snakes and lizards are emerging from their winter slumber. It is exceptionally dry and food is scarce. With each footstep the cassowaries take, the leaves crackle and this could alert large predators like the 1m+ goannas that inhabit the forest. They could easily down a small cassowary but they would have to contend with its father and this would inhibit a goanna, especially if it had some experience along these lines. Pythons could also pose a problem at night but the chicks are usually tucked well under the father as they sleep. But a disturbance, like a troupe of marauding feral pigs, might cause him to bolt and abandon the chick.

Good luck to both. If the chick survives this season, it will be a very lucky bird. I will keep you posted.

A Small Mystery Solved

A recent trip to the dry (very dry) open mixed woodland north of Mareeba, Queensland started out as a bit of  bust. there was almost no insects activity during the day. But after dark it was different. Many moths and other insects were  attracted to the light sheets.

We usually wander around whilst the lights do their work. I stumbled (literally) upon this damaged mantis ootheca and right along side it there appeared to be some mysterious
"puparia".
At first glance I thought they must be the puparia of a parasitic wasp, for example the Braconidae, parasite wasps that produce similar-appearing puparia once they emerge from their host. But they are usually associated with caterpillars.

I took the branch back for closer examination.
This revealed that they were not puparia at all but eggs. But eggs of what? So I contacted several colleagues, both nationally and internationally. Prof Andy Austin of Adelaide University hit the nail on the head. He thought they might be eggs of an Assassin Bug, family Reduviidae.
Sure enough, that is exactly what they are. A couple of weeks after they were collected dozens of Assassin Bug nymphs emerged.
From the tangle of legs and antennae it is easy to recognise that they are Assassin Bugs.
There were two distinct colour morphs. The golden nymphs may be newly emerged and have not yet coloured up. Note the beak. Assassin Bugs are predators and puncture their prey and suck the bodily contents of the victim through the straw-like beak.

Now why are the eggs so close to the mantis ootheca? Did Mrs Assassin Bug have a feed of the eggs and deposit her eggs right there? Both the mantids and the bugs are predaceous and very hungry when they hatch. Was there a method in her madness, or was this just happenstance? Probably the latter as I know of no other instances of Assassin Bugs depositing eggs near a potential food source. Any thoughts on the matter? And if she ate the mantis eggs, there would be no mantis nymphs to emerge from the ootheca.


Wednesday, 8 October 2014

A Bit of Good Luck

Most gardeners, naturalists and entomologists have seen Green Lacewing (family Chrysopidae) eggs in nature. I must have seen hundreds of them but had not encountered the egg-laying female until the other night in the Daintree region of far north Queensland. Unfortunately it was very windy and it was very difficult to take the photos, shelter the female lacewing and steady the camera all at the same time. The eggs are usually laid on the underside of vegetation but they can be found on buildings, garden furniture and the like.

I managed to get some photos that are not too bad considering the less than favourable windy conditions at the time.
 After depositing an egg.
 The female actually laying the egg. An enlargement below.
A thread of silk(?) is made first followed by the egg. The eggs are on stalks supposedly to delay or prevent the hatching larvae from eating one another. One would think that staggering emergence times would solve that problem.

Once the larvae are ambulatory, they are voracious feeders. They consume any small insect they can subdue. This habit has earned them a good reputation as biological control agents. Several species are sold commercially to the agriculture trade.

Saturday, 4 October 2014

Spring Moths

It is spring in the Southern Hemisphere. The days are getting longer and the nighttime temperatures are higher than they have been. But it is dry in the north. Kuranda rainfall during August was 55 mm and for all of September only 4.00 mm.

Nevertheless, it does not seem to affect moth activity. Warmer nights have yielded a great variety of species that were not present just a couple of weeks ago. Here is a very small sample.

Thanks to Ted Edwards, Ian McMillan and Buck Richardson and Donald Hobern for aid with the identifications. Any errors are those of the ageing yours truly.

For an idea of scale, the squares of the light sheets measure approximately 1 mm across.
Drepanidae; Hypsidia erythropalis

 Xylorictidae; Cryptophasa flavolineata
 Erebidae; Ctenuchinae; Ceryx guttulosa 
 Crambidae; Glyphodes margaritaria
Crambidae; Pyraustinae Omiodes chrysampyx
 Saturniidae; Saturniinae; Coscinocera hercules- Male The Hercules Moth
  Saturniidae; Saturniinae; Coscinocera hercules- Male The Hercules Moth
 Erebidae; Lithosiinae; Termessa ANIC sp. 2
 Erebidae; Lithosiinae; Asura polyspila
Erebidae; Lithosiinae; Genus ?
  Crambidae; Pyraustinae; Proedema  inscisalis
Notodontinae; Syntympistis chloropa
Oecophoridae; Oecophorinae Garrha sp. ANIC 13
Oecophoridae; Oecophorinae Lophopepla triselena
Saturniidae; Saturniinae Opodiphthera fervida
 Pyralidae; Phycitinae genus ?
 Pyralidae; Endotrichinae Endotricha sp
 Crambidae; Pyraustinae Palpita unionalis
 Xylorictidae; Genus ?
 Xylorictidae Xyloricta sp
Cosmopterygidae; Trachydora sp
Erebidae; Hypeninae Meyrickiella torquesaria 
 Oecophoridae; Stathmopodinae Zatrichodes sp
 Crambidae; Pyraustinae Pleurotypa symphonodes
 Adelidae; Nemophora panaeola
  Adelidae; Nemophora panaeola
 Crambidae; Acentropinae Megarosticha sp
 Geometridae; Geometrinae Agathia distributa 
  Geometridae; Geometrinae Gelasma orthodesma
 Geometridae; Geometrinae Metallochlora venusta
 Crambidae; Crambinae Genus?
 Batrachedridae Batrachedra sp
 Geometridae; Ennominae Milionia queenslandica
 Gelechiidae undescribed genus
 Aganaidae; Agape chloropa
 Erebidae; Arctiinae; Amerila crokeri
 Plutellidae; Plutella ?xylostella-The Cabbage Moth
This moth is a garden pest of many vegetables of the cabbage family. As far as I know, this is the first record from my home in the rainforest. Many people attempt to grow veggies and this must be the source of this species which may be introduced in Australia. There is some confusion as to the identity of the species and, therefore, the precise application of the species' name.

Geometridae; Oenochrominae Oenochroma quadrigramma