Stylops!!

Remember to click on the photos to enlarge


Members of the insect order Strepsiptera are frequently collected by entomologists but few recognise them for what they are. These insects are internal parasites of a variety of insect orders. Most have complex life histories. First instar nymphs are free-living and look nothing like either parent. Females are obligate internal parasites of their hosts in all but one family whilst males are free-living for a very brief period during which they find the female, mate and then die.

Females often appear as a dark spot on the abdomen of the host. This can easily be overlooked as a wound or other imperfection by casual collectors.

Strepsiptera are believed to be most closely related to the beetles. The fore wings of male strepsipterans are reduced and the hind wings are expanded for flying. This is similar in some respects to beetles of the family Rhipiphoridae. 

Members of the order Strepsiptera are often called "stylops". This is a bit of a misnomer because the Stylopidae is only one of several families in the order. Insects that are parasitised by strepsipterans are said to be "stylopised" to add further confusion. 

Some 30 species of Strepsiptera have been described from Australia. They are parasites of a fairly broad range of insects. Silverfish, orthopteroid insects, bugs, flies, bees and wasps are known hosts. They have been studied extensively by J. Kathirithamby and her colleagues.

Recently my friend Graeme Cocks discovered a male "stylops" in one of his Malaise traps. His photos are of such excellence that they prompted this blog.

G Cocks photo

G Cocks photo

This appears to be a species in the family Corioxenidae, subfamily Corioxeninae. These insects are parasites of bugs (Heteroptera). 

The forewings are the dark twisted structures just behind the eyes. Both the eyes and the thickened grey antennae are peculiar and are probably involved with host-finding. Males have only a few hours to find their mates in some species.

A few days later while collecting and photographing insects on Mt Baldy, near Atherton, Queensland I found a female Cone-headed Katydid, Pseudorhynchus sp.,  with the tell tale dark mark of a stylops on its abdomen.

Pseudorhynchus sp., female

dark spot of a stylopised insect

Dissection of the abdomen of the katydid revealed that its eggs were intact seemingly unaffected by the parasite. The sac-like abdomen of the parasite was tightly affixed to the hosts abdominal wall where it did not seem to interfere with any bodily function of the host. If so, this is quite different from some of the examples of other hosts. Behaviour, structure and sexuality can be severely changed in certain bugs, for example. The only "odd" aspect of the katydid was that it is slightly smaller than I would have expected from a female of its species. 

From what I can tell, this is a very different species from the male Graeme photographed. It seems to be a member of the family Halictophagidae.

What you see is the opening called the brood passage, the mandible, maxilla and probably the antenna of the female. Males fertilise females through the brood passage. 

Katydid's abdomen opened to expose the entire female "stylops". 

The Strepsiptera are an unusual group of highly modified insects. Their morphology and biology  have been relatively well-studied compared to many other insect groups.

I am grateful to Graeme Cocks for allowing me to use his excellent photos of the male he found in his trap.

Christmas Stags

Some of the locals that are flying at this time of year.

Mueller's Stag Beetle-an iconic Queensland insect: Phalacrognathus muelleri male

Phalacrognathus muelleri male
38 mm

Phalacrognathus muelleri female

28 mm

Lucanidae: Cacostomus squamosus male
25 mm

Lucanidae: Prosopocoilus torresensis female

22mm

Special thanks to Jack Hasenpusch for identification of the last example.

A Couple of Nice Moths

There are thousands of species of moths in the northern tropics of Australia. Patterns and colours seem endless. Here are a couple that I found quite attractive.

The depressariid is very elegant. Larvae of some species are leaf feeders and tie leaves together with silk and use faecal pellets to form silken galleries.  this is a rainforest species.

 Despressariidae; Barantola pulcherrima

Limacodidae; Comana albibasis

Limacodids are called "cup moths". There are about 70 species in Australia. The larvae are slug-like and can defoliate trees. The biology of Comana species is largely unknown. 

Click on the images to enlarge

The holes in the light sheet are about 1 square mm.

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.

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.