A quick Conocephalus primer

Conocephalus is a terrible terrible genus with 40+ species that all look the same, and the majority of them are undescribed. You will not get an ID. That's the end of this post.

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Okay, so not quite :P
We can definitely put some names on some of the species without difficulty, even though there are just so many undescribed species across Australia. We can roughly divide the species into an 'easy group' and a 'hard group', and in this post I'll give you a very quick overview of how to differentiate these species. I'll mostly stick to the described species but you can see some of the undescribed species here. Here are a couple of them:

We'll go through the described species more or less in order of 'ease of identification'.

Conocephalus tumultuosus is probably the easiest species to differentiate simply because of its colour scheme:

No other species has blue and orange as far as I'm aware. It's known from northern NT and does not appear to be common.

Conocephalus vaginatus should also be fairly easy to identify, or at least the group of species related to it should be. They are very elongate, slender katydids with long, straight ovipositors:

If you look closely you will see that this individual has very small wings. True C. vaginatus is completely wingless, but this undescribed species is closely related. They come in green or this pinkish brown. True C. vaginatus has been recorded from northern NT, whereas these undescribed species have also been recorded in inland Queensland.

Of the common species, the easiest to ID by far is Conocephalus semivittatus semivittatus. Males have extensive black on the surface of the abdomen and black stripes down the side of the abdomen:

Females have a brown dorsal surface to the abdomen with a black border of varying width. Sometimes it is very thin and almost nonexistent, and other times it is broad and extended downwards into stripes like in the male. This one has a decent amount of black:

C. s. semivittatus has a broad range from eastern Victoria up to SEQ. It's also found on Lord Howe Island and in New Zealand.

Although the short-winged form is much more common, a long-winged form is also known for both sexes. Abdomen colour is still probably the most useful way to distinguish it from other species, although that will be more difficult for females.

The northern 'subspecies', Conocephalus semivittatus vittatus, is broadly similar to C. s. semivittatus but there are several notable differences. I say 'subspecies' because in reality they are two different species, although they are certainly closely-related.

In the male, the abdomen has some brown on top, the black stripes are vague to absent, and there are usually a few white spots on the abdomen:

Females are even more distinctive - they are darker dorsally than their southern counterpart, and have an obvious row of white spots on each side of the abdomen:

Just as with C. s. semivittatus, long-winged forms exist but are much less common.

C. s. vittatus is found in FNQ in rainforest-adjacent areas including the Wet Tropics and Iron Range. It's also known from New Guinea and I think further afield as well.

C. bilineatus is another fairly easy-to-distinguish species, at least in females. The abdomen of both sexes is brown dorsally, and then this is bordered by a thin black stripe and a thicker pale stripe:

The overall body colour can be either brown or green. Males are similar in colour to females:

Long-winged forms of this species exist as well and they are harder to differentiate unfortunately. In the short-winged form though, the end of the male's tegmina are quite broadly rounded (this will be important later!).

Another very useful ID feature is the pronotum - almost always, the lateral lobe has a dark stripe and then immediately underneath this is a pale stripe. It's not always present, but no other species has both of these stripes.

C. bilineatus is found in southeastern Australia from the Eyre Peninsular up almost to the NSW-Qld border, although it seems to be quite rare in Sydney. Its range includes Tasmania where it is quite common. Outside Australia it is also found in New Zealand.

Now we start getting to the species that are a bit more difficult. Conocephalus redtenbacheri is distinctive but in a more subtle way. It has some obvious yellow patches on the sides of the abdomen and the posterior thorax:

These yellow patches vary a bit in intensity but are generally more extensive in the male, which also has some reddish areas on the dorsal surface of the abdomen:

C. redtenbacheri has a mesopterous form (the two pictured above) and a proper long-winged form, both of which seem to be about equally common.

Its known from coastal Queensland from the Wet Tropics down to near Mackay, and is also known from New Guinea and several Pacific Islands where there are also some lookalike species that are very difficult to separate.

Conocephalus maculatus is a very distinctive species once you see the difference between it and the other species, but if you don't know what you're looking for then it is very 'samey':

The key is the pattern on the wings - the costal region (the lowest section in the photo above) is completely patternless, and the region above this has a row of large black spots. Compare that with images of other macropterous species, which generally have the costal region darkened and no large spots anywhere on the wings.

C. maculatus is only known from long-winged forms, so these spots will always be clearly visible.

In Australia the species is known from north Queensland and northern NT, but it's very widespread outside of Australia and is known as far as Africa.

Conocephalus laetus is... an odd species. And it's mostly odd because it's hard to describe exactly how it's odd.

The stridulatory region is very large, the back of the pronotum is raised, and the colours are overall quite muted. Once you get a feel for Conocephalus you will start to notice that this species just 'feels' very odd though.

C. laetus is uncommon through the drier areas of northern Australia from WA to Qld. It's also widespread outside Australia and has similarly been recorded as far as Africa (supposedly).

Conocephalus willemsei is getting towards the harder end of the scale. It is fairly indistinctive, although the males have a significant amount of yellow on the abdomen:

Females are unfortunately very much less distinctive and I don't really have any good tips. The moderately long, straight ovipositor is useful at least:

C. willemsei is known from northern NT, and additionally in New Guinea.

Our final two described Australian Conocephalus are the problem children, the two most difficult to separate. Conocephalus albescens and Conocephalus upoluensis are both very common and are among our most-observed species.

Here are some individuals of C. albescens:

And here are some individuals of C. upoluensis:

So, what's the difference? Good question. Probably the most obvious and helpful thing is that C. albescens can be either long- or short-winged, whereas C. upoluensis is always long-winged. The short-winged males of C. albescens are quite similar to those of C. bilineatus, but C. albescens has the tegmina longer and distinctly more pointed, as compared with the tegmina of C. bilineatus which are shorter and much more truncately rounded.

Distribution is also very helpful. C. albescens is known in the southeast across a similar range to C. bilineatus, from the Eyre Peninsula all the way up to about Brisbane, including Tasmania. It's also found in New Zealand. C. upoluensis is incredibly widespread and is found over the entirety of Australia. It's probably our only species through most of central Australia and in the southwest. It does appear to be less common in Tasmania but everywhere else it is one of the most common species. It's also found on Norfolk Island, and additionally from New Guinea and through the Pacific (but not New Zealand, oddly enough).

So if you have a long-winged individual from where their ranges overlap, how do you tell them apart? Well, then it gets more difficult. I will list off some good features here, but sometimes it just won't be possible, especially with males. Nymphs are almost impossible for the most part, although subadult females can be identified.

• In female C. albescens, the ovipositor is long and extends beyond the end of the wings. In female C. upoluensis, it is much shorter and does not reach the end of the wings. Often it is tucked away so that the end is not actually visible at all. So if you can see the end of the wings in a female, you should be able to tell them apart.
• In male C. albescens, the cerci are very narrow distally and are often darkened. The tenth tergite (dorsal segment at the end of the abdomen) is also produced downwards on its posterior edge (sorry this is not as visible in the photo below). In male C. upoluensis, the cerci are not narrowed or darkened distally, and the tenth tergite is not produced downwards. Compare C. albescens on the left and C. upoluensis on the right:

• In C. albescens, the legs are sometimes a different colour to the abdomen. In particular, often the legs are brown and the abdomen is greenish. In C. upoluensis, the legs and abdomen are always more or less the same colour.
• In. C. albescens, the dorsal surface of the pronotum is always more than half brown, and it's almost always entirely brown. In C. upoluensis, the dorsal surface of the pronotum can be green or brown.

So there ends our quick little intro into the terrifying world of Conocephalus ID. As I said at the start, we have about 40 undescribed species across Australia, so there's a big job ahead to describe them all! At least the most common species are described. And like the last post, we can show them in a lovely little map that my computer struggles with. But hey, it looks nice!

And that's all done with Conocephalus.

Everything all wrapped up nicely.

No more species to look at.

Definitely not.

What's this, there's more???

Well we can't very well look at Conocephalus and not talk about everyone's favourite lookalike.

So, the question of the hour: how exactly do you tell Conocephalus from Conocephalomima?

Conocephalomima barameda is an odd katydid. It's in the subfamily Listroscelidinae, almost on the other side of the katydid family tree to Conocephalus, and yet it looks so incredibly similar to Conocephalus that it can be very difficult to tell the two apart unless you know what you're looking for. Why is it so similar?? I don't think anybody knows.

Anyway, how do we tell the difference then? There are numerous features, and the more you look at the two genera the more you will see that they are actually quite easy to differentiate.

Firstly, let's look at range - Conocephalomima is found only in the southeast of the country, from SEQ around the coast to western Victoria (but excluding Tasmania). Let's take a look at a female and compare her to the Conocephalus species above:

The most obvious difference should be the thick, curved, sickle-shaped ovipositor. No Australian Conocephalus has an ovipositor even approaching this, and it's by far the easiest difference to see. Of course, it's only visible on females but it's very visible and should become obvious even in thumbnails once you've looked at enough individuals.

The other differences are a bit more subtle but you start to get the hang of them. The tegmina are very narrow and don't narrow towards their ends (in fact the seem to slightly broaden), and importantly they're held well above the abdomen. In Conocephalus the wings are held quite close to the abdomen and it's rare that you would see the dorsal or even upper lateral portions of the abdomen.

The front and mid legs are proportionally rather more robust than in Conocephalus, and they have larger spines as well. The hind legs are also a bit longer, extending well past the end of the abdomen and almost to the end of the ovipositor.

The pronotal lobes are also rather shorter and do not completely cover the prothoracic holes, whereas in Conocephalus these holes should never be visible.

Barring the ovipositor, all of these features are present on males as well:

Males additionally have very different cerci to Conocephalus - they have no internal spine, and are instead strongly curved inwards and usually darkened as well.

Nymphs are similar to adults but of course lack wings:

And tiny babies are also quite distinctive:

But there's one feature I haven't mentioned yet, and it's the most important feature because it's easily visible on both sexes at all life stages. This one feature can always differentiate Conocephalomima from Conocephalus. It's got to do with the head!

So first of all, the head of Conocephalomima is much rounder and broader than that of Conocephalus, which tends to have quite a narrow and often pointed fastigium. But more importantly, have a look at the colour and the pattern. In both Conocephalomima and Conocephalus, the laterodorsal stripes on the pronotum extend onto the head. In Conocephalomima, these stripes diverge anteriorly and meet the eyes, where they stop, and the interior section between them becomes more green anteriorly until there are no brown markings at all. In Conocephalus, the stripes go between the eyes and meet up at the fastigium, and usually the interior section between them remains brown along the whole head. This is the most important differentiating feature, and luckily for us it's almost always visible because people tend to photograph the head end of most animals!

If you want to have a go at testing yourself on the difference between Conocephalus and Conocephalomima, have a scroll through the observations here and see if you can pick without looking at the names :P You'll get better the more you look at them until it will become easy peasy.

Anyway, that's about it for this post. No key or summary stats this time around because there are so many undescribed species and they're just a difficult group in general. And to be perfectly honest, the main point of this post is so that I don't forget everything I just spent the past few months learning!

Posted on September 27, 2023 08:00 AM by matthew_connors