Mozambique Diary: Is this tortoise broken?

Apr12
An adult Hingeback tortoise (Kinixys belliana) from Gorongosa. What looks like a wound on its carapace is a flap of skin that allows the shell to close and protect the hind legs and tail.

An adult Hingeback tortoise (Kinixys belliana) from Gorongosa. What looks like a wound on its carapace is a flap of skin that allows the shell to close and protect the hind legs and tail.

Some time ago I was driving in Gorongosa when I noticed a large tortoise laying in the middle of the road, stuck upside down in the mud. The animal was alive but had what appeared to be a large wound in the posterior part of its cracked carapace. There were fresh tracks of a civet all around it in the mud, and I assumed that the civet found an injured tortoise (I didn’t think a civet could do it itself) and was hoping to eat it. I pulled the animal out of the muck and only then recognized what I was looking at – the tortoise was not injured at all, and what I took for a wound was a flap of skin that connected the front part of the shell with its movable back. Because it was not an ordinary tortoise, but a Hingeback tortoise (Kinixys), a member of a remarkable group of reptiles that are capable of closing shut the back of their shells to protect the hind legs and the tail. This, combined with the head tightly pulled into the front of the shell and blocked by its heavily armed front legs makes the hingeback tortoise virtually immune from attacks by smaller predators. Judging by the dense trail of civet tracks around the tortoise it seemed that the mammal had spent a lot of time in frustration, unsuccessfully trying to get to the soft parts of the reptile.

A juvenile Hingeback tortoise; its hinge is not yet developed.

A juvenile Hingeback tortoise; its hinge is not yet developed.

Although the movable carapace is a great way to protect the rear part of the body, the flap of skin that connects the two components of the carapace is a favorite location for another enemy of the tortoises to attack – the ticks. Every tortoise I found in Gorongosa carried several huge, heavily armed ticks (mostly of the genus Amblyomma), whose body shape and sculpturing was surprisingly similar to that of the tortoise. Carrying a bunch of blood-sucking ectoparasites is no fun, but the burden of being drained by them is probably particularly heavy on smaller, younger animals. A few days ago I found a tiny Hingeback tortoise, one whose hinge was not yet fully developed, and it carried on its leg one of the largest ticks I have ever seen. It was as if I had a parasite the size of a football permanently attached to my body. I removed the tick from the tortoise, put one of the animals into a vial of alcohol, and applied some antiseptic to the other and let him back on his merry way.

An enormous tick (Amblyomma sp.) on the tortoise's leg.

An enormous tick (Amblyomma sp.) on the tortoise’s leg.

Hingeback tortoises are quite common in Gorongosa, and I see them often as they cross the network of trails. But across Africa their numbers are declining as the result of habitat loss and collecting for the pet trade. Every year about 20,000 of these animals are exported to be sold in pet stores in the US and Europe, and Mozambique alone sends out about 3,000 of these animals every year (this is the official quota allowed by CITES, the actual number is undoubtedly higher). Luckily, recently the importation of most of Hingeback species was banned in the US. The reason – ticks. Some of the ticks carry a disease which, while not harmful to the reptiles, is often fatal to cattle – the Heartwater disease, caused by rickettsia Ehrlichia ruminantium. And so, the same parasite that makes the tortoises’ life miserable may in the end help them survive in the wild. I guess you never know who your true ally is.

Tortoise tick (Amblyomma sp.) actually looks like a tortoise, and its opisthosma is almost as hard as the reptile's shell.

Tortoise tick (Amblyomma sp.) actually looks like a tortoise, and its opisthosma is almost as hard as the reptile’s shell.

Mozambique Diary: Sylvan katydids of Gorongosa

Apr8
Male Elegant sylvan katydid (Acauloplax exigua) in his typical resting position.

Male Elegant sylvan katydid (Acauloplax exigua) in his typical resting position.

A few nights ago, as I was walking towards my cabin along the edge of the Chitengo Camp, I heard a call of a cricket that I did not quite recognize. Cricket calls are unmistakable for their clean, almost melodious quality, very different from the call of a cicada or a katydid, which tend to be more “noisy.” But his call was very pure, almost bird-like, and it was coming from high in a tree. I expected to find a black, wide-winged Homoeogryllus cricket among the leaves, but to my delight the mystery caller turned out to be a gorgeous Blue-legged sylvan katydid (Zabalius ophthalmicus). This and a few related species produce some of the most pure tone, almost whistle-like calls, a rarity among katydids.

Sylvan katydids (Pseudophyllinae) are uncommon in this part of the continent. The greatest diversity of these insects is found in the rainforests of Central and West Africa, where most live high in the canopy. In Mozambique I expected to find only four species, and indeed found them all in Gorongosa (which of course is not to say that more are not to be discovered.) Virtually all sylvan katydids, true to their common name, are associated with forests and other woody habitats, and few are found in the open savanna.

Southern African sylvan katydids display two very distinct types of mimesis (camouflage). Species found in the canopy of broad-leaved trees (e.g., Ficus) are superb mimics of foliage, complete with leaf-like venation of their wings and fake fungal spots or other “damage.” During the day they rest with their wings spread flat against the lower surface of the leaf, and are absolutely impossible to find. (Interestingly, this type of behavior does not occur in any katydid species found in the New World – all North and South American katydids hold their wings in a vertical position, and during the day rest on twigs with their wings facing up in an imitation of a small leaf.)

Greater bark katydid (Cymatomerella spilophora)

Greater bark katydid (Cymatomerella spilophora) in the woodland of Gorongosa

The second group of species of Mozambican sylvan katydids are bark mimics. These species are associated with more open habitats, mostly miombo or mopane woodland, and spend the day resting on trunks of small-leaved trees, such as Acacia or Brachystegia. Their wings are held similarly flat against the bark, and their coloration is mottled, resembling the surface of the trunk. In addition, their legs are strongly flattened and covered with dense hairs, which helps them eliminate the shadow cast by their bodies.

One of the Mozambican species, The Common bark katydid (Cymatomera denticollis), is unusual among katydids in its ability to produce chemical defenses. Production of repellant chemicals has been documented in a few Neotropical species, but this is the first example of such a behavior in an African species. These insects, when threatened by a predator, fan their wings and reveal a brightly colored, red, orange, and black abdomen. At the same time a gland on their abdomen sprays a strongly smelling liquid. I have had no chance to look into the chemical composition of this substance, but its smell is very much reminiscent of that produced by their (unrelated) South American counterparts. In those katydids the repellant substances were identified as methylpyrazines, and I would not be surprised if the African species produced related compounds.

A song of the Blue-legged sylvan katydid (Zabalius ophthalmicus). Click here to listen to the recording: first played at the normal speed, followed by a fragment slowed down by a factor of 10 (for the katydid-challenged listeners, i.e., most males over 35).

A song of the Blue-legged sylvan katydid (Zabalius ophthalmicus). Click here to listen to the recording: first played at the normal speed, followed by a fragment slowed down by a factor of 10 (for the katydid-challenged listeners, i.e., most males over 35).

Female Elegant sylvan katydid, showing fake leaf damage and leaf-like venation on her wings.

Female Elegant sylvan katydid, showing fake leaf damage and leaf-like venation on her wings.

Sylvan katydids of Gorongosa in their typical daily resting poses: Blue-legged sylvan katydid (Zabalius ophthalmicus), Elegant sylvan katydid (Acauloplax exigua), Common bark katydid (Cymatomera denticollis) and Greater bark katydid (Cymatomerella spilophora).

Sylvan katydids of Gorongosa in their typical daily resting poses: Blue-legged sylvan katydid (Zabalius ophthalmicus), Elegant sylvan katydid (Acauloplax exigua), Common bark katydid (Cymatomera denticollis) and Greater bark katydid (Cymatomerella spilophora).

Mozambique Diary: Manticora

Apr5

A male Monster Tiger Beetle (Manticora latipennis) killing one of his favorite prey items, a grasshopper (Humbe tenuicornis) [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

A male Monster Tiger Beetle (Manticora latipennis) killing one of his favorite prey items, a grasshopper (Humbe tenuicornis) [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

Things have been busy here in Chitengo, and I am struggling to find time to update the blog amidst the preparations to our upcoming biodiversity survey of the Cheringoma Plateau. But I simply cannot resist mentioning one of the most remarkable creatures that I have had the pleasure to meet in Gorongosa. Every biologist has a list of organisms that he or she is particularly keen on seeing at least once in the wild. My list is long, but a few days ago I managed to check off it Manticora, or the Monster Tiger Beetle.

With a name like this one would expect a rather extraordinary beetle, and one would not be disappointed. Named after a mythical beast with the body of a lion, head of a man, and the tail of a scorpion, the real-life Manticora may not be as monstrous, but it is nonetheless a stunning animal. It is the world’s largest tiger beetle (Cicindelinae), with a robust, heavily sclerotized body that easily reaches 65 mm in length. Its head, especially that of the male, is equipped with a pair of mandibles that would not look out of place on a stag beetle but, unlike the mostly ritualistic function of large mandibles in stag beetles, those of Maticora are very much functional.

The mandibles of a male Manticora latipennis are truly impressive. In addition to catching and killing prey, males use them hold and guard a female during copulation. [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

The mandibles of a male Manticora latipennis are truly impressive. In addition to catching and killing prey, males use them hold and guard a female during copulation. [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

Despite its size Manticora behaves in a way quite similar to smaller tiger beetle species. Its movements are agile, and it can run like hell and change direction in a split of a second; they cannot fly, however. These beetles hunt anything that moves, although prefer orthopterans, but unlike other tiger beetles it appears that the sense of smell rather than vision is their main tool for locating their victims. Once prey is located the beetle clasps it with its enormous mandibles and literally chops it to pieces. I watched it find and kill a large wolf spider – at first I thought that the spider would put up a fight, but about two seconds later what was left of the spider was a nicely masticated ball of tissue and a small pile of legs. After the main body was consumed the beetle picked the legs, one by one, off the ground and ate them, too. Interestingly, the beetle, which was a male and thus his mandibles ware particularly large, used its maxillae rather than the mandibles to pick up the leftover bits of prey, a behavior I have not seen before in a beetle.

A spider found by Manticora did not stand a chance – in a couple of seconds all that was left of the animal was a pile of body parts. [Canon 6D, Canon 16-35mm + an extender, Canon MT-24EX twin light]

A spider found by Manticora did not stand a chance – in a couple of seconds all that was left of the animal was a pile of body parts. [Canon 6D, Canon 16-35mm + an extender, Canon MT-24EX twin light]

Manticoras have a bimodal pattern of activity, hunting mostly early in the morning, and then again around sunset and, contrary to a frequently repeated misconception, they are not nocturnal. This is likely because of the competition from other, mostly nocturnal ground beetles (Anthia and Termophilum), which are also common here.

A male Manticora with prey [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

A male Manticora with prey [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

The discovery of Manticora in Gorongosa has also solved a small mystery for me. About a week ago I witnessed a strange sight – a very large antlion of the genus Palpares, an insect the size of a small bird, was slowly disappearing, head first, into a perfectly round hole in the ground. That just did not compute, and I had to see what was causing this behavior. I tried to pull the antlion out and something pulled back. But the mystery animal’s strength was no match for my mighty human strength, and I freed the antlion, but not before catching a glimpse of a large, flat head about the size and shape of a penny, disappearing deep into the perfectly vertical tunnel in the ground. Tiger beetles have larvae that behave in exactly this way, and now I am convinced that I stole the prey from a Manticora larva. Next time I see a similar tunnel I will try to find the larva and photograph it.

I have read in several places that the male Mantcora's enormous mandibles are not good at catching prey – not true, they are excellent killing devices! [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

I have read in several places that the male Mantcora’s enormous mandibles are not good at catching prey – not true, they are excellent killing devices! [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

 

Mozambique Diary: A talking grasshopper

Mar31

A male Cataloipus cognatus munching on grass. [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

A male Cataloipus cognatus munching on grass. [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

One of the most endearing characteristics of grasshoppers is their ability to produce sound. Some of the most wonderful memories of my childhood include sitting in a meadow bursting with sounds of insects and watching grasshoppers use their hind legs to produce soft, rhythmical songs, and not realizing that a seed that would eventually blossom into a full-blown career in entomology is sprouting in my brain.

Despite the strangely persistent misconception, the sound of grasshoppers is not produced by rubbing their legs together (in fact, no insect makes sound in this way), but rather by dragging the inner side of the hind femur against a thick vein on the front wing (depending on the group, either the femur or the vein is armed with a row of stridulatory pegs). But this ability to produce loud songs is far less common among grasshoppers than it may appear to somebody who grew up in Europe, one of the few places in the world where members of the vociferous subfamily Gomphocerinae dominate the grasshopper fauna. I was surprised how few grasshoppers sing in North American or Australian meadows, and tropical grasshoppers of South America and Africa are almost all silent.

Females of C. cognatus are much larger than the males; they are also completely silent, whereas males produce a loud mandibular stridulation. [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

Females of C. cognatus are much larger than the males; they are also completely silent, whereas males produce a loud mandibular stridulation. [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

I was therefore quite startled when I caught yesterday in Gorongosa a beautiful grasshopper Cataloipus cognatus, and the insect responded to this violation of its freedom by producing loud and persistent squeaks. It took me a while to discover how the sound was produced. At first I thought that it was using its hind legs to make the sound, but this lineage of grasshoppers (Eyprepocnemidinae) lacks stridulatory pegs on their legs, and besides, I was holding it by the legs and thus it couldn’t use them even if it wanted to. Looking closely I realized that the grasshopper’s sound was coming from its mouth. I knew of a katydid species that was capable of stridulating with its mandibles, but had no idea that some grasshoppers could also do it.

Just to be sure I caught a few more individuals, and some made the sound while others didn’t. Then I noticed that the silent ones were all females, while all males were producing the sound. Since I don’t have a microscope here in the Chitengo camp (yet, one is coming soon, fingers crossed), I could not look at the structure of the sound-producing apparatus. But I recorded the sound and looked at its oscillogram, which revealed a clean, evenly spaced pattern of pulses, which is indicative of the presence of a distinct stridulatory file. This, combined with the fact that only males produce sound, seems to suggest that the sound might be used not only as a defensive signal, but rather that it may play a role in courtship. If this true, and I will try to confirm it by watching the courtship behavior of this species, it would make a very interesting case of independent evolution of courtship stridulation in eyprepocnemidine grasshoppers.

An oscillogram of the mandibular stridulation of C. cognatus; click here to listen to the sound.

An oscillogram of the mandibular stridulation of C. cognatus; click here to listen to the sound.

Mozambique Diary: Playing a detective

Mar30

Mysterious beetle larvae in a tree cavity in Gorongosa. [Canon 6D, Canon 100mm macro, Canon MT 24EX twin light]

Mysterious larvae in a tree cavity in Gorongosa. [Canon 6D, Canon 100mm macro, Canon MT 24EX twin light]

For an entomologist few pleasures in life are greater than arriving in a new geographic area and being stumped by unfamiliar and mysterious insects, often ones that he/she had never suspected existed. I had a moment like this last night, when I ran across a strange, metallic blue insect, about 25 mm long, walking on the sand in Chitengo. My first thought was that it must be a blattodean, some of which are wingless and have a dark, metallic sheen. But when I picked it up I realized that it was a beetle larva. I knew it because the insect lacked well-developed tarsi or any traces of wings or wing pads, and its antennae consisted of only two articles (although one was exceptionally long). But what family? Ground beetles (Carabidae) often have strange, active larvae that hunt insects in sandy areas, and this was my guess.

Then I happened to look up at the trunk of a nearby tree and saw several dozens of these larvae huddled in a small cavity about 2 m above the ground; the one I found must have fallen off the tree and was trying to find its way back home. I concluded that it couldn’t be a carabid as their larvae are ground-dwelling predators and thus unlikely to (a) live high in the trees and (b) form large aggregations.

A cluster of pupae in a tree cavity. [Canon 6D, Canon 100mm macro, illuminated with a headlamp]

A cluster of pupae in a tree cavity. [Canon 6D, Canon 100mm macro, illuminated with a headlamp]

A few meters away another tree had a second colony of these insects, but this one was a little older. Although it still had a few larvae moving around, most had already metamorphosed into pupae, which were hanging in grape-like clusters, eerily reminiscent of a scene from the movie “Alien”. There were about 50 of them hanging together, but the tree cavity was very deep and narrow, and I couldn’t get a good photo of the group. I had never seen beetle pupae hanging in a similar formation. The mystery deepened.

I shone a light into the cavity and squeezed my hand in to scoop one of the pupae. At that moment I noticed two adult beetles, which seemed to be guarding the cluster. They were clearly a male and a female since one individual was slightly larger and had distinctly thickened front legs with a pair of large spines; I assumed that it was the male. Both beetles ran away when I put my hand in, but quickly returned and assumed the same position near the clutch of pupae.

And they were darkling beetles, or Tenebrionidae! One of the first things you learn in an entomology class is that tenebrionids have elongate, vermiform larvae that burrow in the ground, and for this reason it never crossed my mind that the blue, free-running larvae in the tree might belong to this family. A cursory search of coleopterological literature revealed that my beetles may be members of a large, nearly cosmopolitan genus Strongylium, of which some species are arboreal. If any any entomologist reading this has another idea, I would love to know it – being stumped by an unknown insect is a pleasure, but never learning its identity is torture.

Update: The identity of this beetle has been revealed to be Pycnocerus sp. (Tenebrionidae: Lagriinae). Thanks to Kip Will and Rolf Albu for this information.

Three developmental stages of a mystery beetle, found together in the same tree "colony", tentatively identified as Strongylium sp. (Tenebrionidae). [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

Three developmental stages of Pycnocerus (Tenebrionidae), found together in the same tree “colony”. [Canon 6D, Canon 100mm macro, 3 x Canon 580EXII]

Mozambique Diary: It’s good to have my gear back

Mar29

To celebrate the miraculous recovery of my photographic equipment from the clutches of South African Airways, today I took my new Canon 400mm for a short spin around the Chitengo camp. I usually do not photograph birds and mammals, but there are so many of them around that it would be a shame not to point a lens at some.

This Yellow baboon (Papio cynocephalus) got in our cabin this morning and stole our bananas. Just a reminder to keep our doors and windows locked, we are on their turf here.

This Yellow baboon (Papio cynocephalus) got in our cabin this morning and stole our bananas. Just a reminder to keep our doors and windows locked, we are on their turf here.

There is a small colony of Village Weavers (Ploceus cucullatus) near my cabin. This male was finishing his nest and frequently displayed if any female was around.

There is a small colony of Village Weavers (Ploceus cucullatus) near my cabin. This male was finishing his nest and frequently displayed if any female was around.

African Pied Crow (Corvus albus) is a handsome, intelligent bird, but for some reason birders tend to ignore this species.

African Pied Crow (Corvus albus) is a handsome, intelligent bird, but for some reason birders tend to ignore this species.

Mozambique Diary: The real birds-of-paradise

Mar27
Once an adult male burrowing mayfly lands on the the surface of the water it dies within a few minutes. (The angel-like halo around this insect's head is a reflection of my flash, which normally I would not tolerate, but in this case it seems appropriate.)

Once an adult male burrowing mayfly lands on the the surface of the water it dies within a few minutes. (The angel-like halo around this insect’s head is a reflection of my flash, which normally I would not tolerate, but in this case it seems appropriate.)

Early Portuguese and Spanish explorers who visited the island of New Guinea in the 16th century were astounded by magnificent, brilliantly colored birds, whose plumage was used by the locals to adorn their headgear and bodies. European naturalists who examined skins of these birds brought back from New Guinea noticed that all specimens lacked legs, and concluded that the birds must have spent their entire life hovering above the ground, akin to angels, and never needed to walk or stand on solid ground. Even Linnaeus was not entirely immune to these legends, and named one of the species Paradisaea apoda, or The Legless Bird-of-Paradise. How silly! Surely, there cannot be an animal that spends its entire life in flight without touching the ground. Or can it?

Yesterday we had a pretty rainy day in Chitengo, which made a lot of insects very happy, including clouds of termites emerging from their underground nests and flying in search of mates. Among the many insect species coming to lights around the camp were strange flying creatures which, once they hit the ground, could never lift off again. At first I thought that those insects must have been injured, but when I picked one up I noticed that the insect, despite having two pairs of large wings, didn’t have functional legs.

Legs of burrwing mayflies (Polymitarcyidae) are reduced to useless stubs and are completely non-functional. Males' front legs are slightly larger and may by used during mating, which also takes place in the air.

Legs of burrwing mayflies (Polymitarcyidae) are reduced to useless stubs and are completely non-functional. Males’ front legs are slightly larger and may by used during mating, which also takes place in the air.

These strange animals turned out to be burrowing mayflies of the family Polymitarcyidae. As larvae these insects develop by digging in the mud of streams and, after completing their aquatic development, winged adults leave the water looking for love. But once in the air, they can never land again. Their legs, especially those of males, are completely atrophied, and cannot be used for walking or even standing. The few short hours that the male mayflies spend as adult insects take place entirely in the air – if they land, they die.

Legless birds-of-paradise from New Guinea turned out to be a fraud, but animals that spend their entire adult life in the air are very real. They may not be as colorful as the birds, but this does not make them any less fascinating.

P.S. Nearly two weeks later after  losing a Pelican case with my photo equipment on a flight to Johannesburg I was today reunited with my luggage, which makes me very happy.