Female Megalopsalis nigricans, copyright Tony.

Belongs within: Palpatores.
Contains: Ballarrinae.

The Neopilionidae are a family of long-legged harvestmen found only on the southern continents, being most diverse in Australia and New Zealand.

Possibly the coolest thing I had published this year
Published 26 December 2009
Dorsal view of male Australiscutum hunti (missing a few legs, I’ll admit). Photo by yours truly.

In 1991, Hunt and Cokendolpher published a paper describing the new harvestman subfamily Ballarrinae and comparing to a selection of long-legged harvestmen from around the globe. In that paper, they referred to an undescribed species of the subfamily Monoscutinae from eastern Australia. For whatever reason, Glenn Hunt never completed a description of this new species before his death but I am happy to say that it has finally been brought into print by Taylor (2009) with the description of three species of the new genus Australiscutum.

Except for the minor detail that Australiscutum is not actually a monoscutine. Monoscutines are small harvestmen from New Zealand; despite belonging to the Phalangioidea, which are known as long-legged harvestmen, monoscutines have relatively short, robust legs. They also have the entire dorsal surface sclerotised (hence the name ‘monoscutine’ or ‘single shield’; in most other phalangioids, only the prosoma or cephalothorax is sclerotised) and ornamented with small nodules. Australiscutum resembles monoscutines in having relatively short legs and while the dorsal surface of the opisthosoma (or abdomen) is not sclerotised, it is covered in small spine-like setae. However, in other features such as genital morphology Australiscutum is quite distinct from monoscutines. Shorter legs and hardened bodies have evolved in a number of different harvestman lineages, such as troguloids and various groups of Laniatores, and are probably an adaptation to a soil-dwelling lifestyle. Though it hadn’t been run at the time I submitted this paper, my phylogenetic analysis of Monoscutidae (for which I’ll probably be submitting the manuscript in a few days’ time) corroborates the lack of a connection between Australiscutum and monoscutines and that the short-legged morphology has arisen twice within the family.

Neat as that is, though, that’s not the really cool thing about Australiscutum. This is:

These are the chelicerae (the pincers) of males of the three species of Australiscutum as seen from the front and to roughly the same scale. Except for the appearance of the chelicerae, the differences between each of the species are relatively minor (though A. hunti is the most distinct of the three). Australiscutum hunti has large swollen chelicerae; A. graciliforceps has much smaller slender chelicerae. But when we reach A. triplodaemon, we see that it has one larger, more swollen chelicera and one smaller, more slender chelicera*. This cheliceral asymmetry is unique among monoscutids and, so far as I’ve been able to find, is unique among harvestmen. In fact, I haven’t yet found any previous record of asymmetrical pincers like these for any arachnid.

*The species name of Australiscutum triplodaemon is a reference to the Triple Demons of Compromise in Norton Juster’s The Phantom Tollbooth. Of these three, one demon was very tall and thin, the second was very short and fat, and the third one looked exactly like the other two.

So far, I can only make a few vague inferences about why A. triplodaemon has these uneven chelicerae, based on comparisons with asymmetrical pincers in crustaceans (where they are known in a number of different lineages). One thing I can say for sure that it is a true morphological feature and not a pathology. If a crustacean such as a crab or lobster looses a pincer while growing, the new claw that grows back may be smaller, but A. triplodaemon can be inferred to have naturally asymmetrical pincers because (a) it’s always the left chelicera that is smaller, and (b) of the other two species in the genus, the one that is closest in appearance to A. triplodaemon (and hence the one that would represent its non-pathological form if it was a developmental accident) is the small-pincered A. graciliforceps and not the large-pincered A. hunti. Many crustaceans develop differently-sized pincers as an adaptation for handling food (for instance, they may use one pincer to hold a prey mollusc and they other to break open its shell) but, again, this seems unlikely to apply to A. triplodaemon as the asymmetrical chelicerae are only found in males. Female Australiscutum have small discrete chelicerae like other monoscutids; unless the females were eating a different diet from the males (not impossible, but unusual), we might expect both sexes to have asymmetrical chelicerae if they were related to food-processing.

The third role that has been recorded for asymmetrical pincers among crustaceans is as part of mating displays (fiddler crabs are the most famous example) and their presence in males only suggests that this is also they role they play for A. triplodaemon*. Determining just how A. triplodaemon uses its odd-shaped pincers will require observation of living specimens.

*Though I say that in the full knowledge that I am largely invoking the old line that “if you don’t know what it’s for, then it’s for display”.

I’d like to share one more interesting thing that came out of the review process for this paper. The two most similar species of Australiscutum, A. triplodaemon and A. graciliforceps, are in fact identical except for their chelicerae. Their recorded ranges also overlap, and the possibility occured to me when I was first describing them that they might be different male forms of a single species. Male dimorphism has been recognised in a number of harvestman species, including monoscutids, but because the mode of dimorphism in Australiscutum would differ from modes described previously I decided that the safest approach for now was to treat the two forms as separate species. I hemmed and hawed as to whether I should point out the possibility of their being dimorphs of a single species in the manuscript but eventually decided that it was perhaps too much speculation on my part and left it out (I tend to be fairly cautious in drawing inferences; I’ve never been able to decide whether this is a good or bad thing). However, when I received the reviewers’ comments, two of the three reviewers had thought of the same possibility without any prompting from me and suggested that I comment on it. So it’s there.

How to wipe out a family
Published 23 February 2011
Male Megalopsalis, probably M. eremiotis, photographed in Victoria by Kennedy H.

Taylor, C. K. 2011. Revision of the genus Megalopsalis (Arachnida: Opiliones: Phalangioidea) in Australia and New Zealand and implications for phalangioid classification. Zootaxa 2773: 1–65.

A morphological phylogenetic analysis is conducted of Australasian harvestmen previously included in the family Monoscutidae. Monophyly of Monoscutidae is not supported, and the subfamilies Monoscutinae and Megalopsalidinae are synonymised with the South American subfamily Enantiobuninae. Monoscutidae is re-synonymised with the family Neopilionidae. The analysis also demonstrates the polyphyly of species previously assigned to the genus Megalopsalis. Megalopsalis epizephyros new species, M. eremiotis new species, M. leptekes new species and M. pilliga new species are described and M. serritarsus and M. hoggi are redescribed, all from Australia. Hypomegalopsalis tanisphyros new genus and species is described from Western Australia. Megalopsalis linnaei is transferred to Tercentenarium new genus. Forsteropsalis new genus is established to include species from New Zealand (including Auckland Island): Macropsalis chiltoni (type species), Pantopsalis distincta, Macropsalis fabulosa, Pantopsalis grayi, Megalopsalis grimmetti, Megalopsalis inconstans, Megalopsalis marplesi, Megalopsalis nigra and Pantopsalis wattsi.

One of the quirks of my PhD thesis was that, by the time I’d finished, it seemed that the family of harvestmen I’d chosen to work on didn’t actually exist. My reasons for coming to that conclusion are presented in a paper published today.

The paper has two major components: one is a taxonomic revision of the genus Megalopsalis, the other is a phylogenetic analysis of what had been the family Monoscutidae. Because phylogenetic analyses of long-legged harvestmen are few and far between (in fact, I’m only aware of one earlier morphology-based numerical analysis), analysing the phylogeny of Monoscutidae required me to also analyse exemplars from other families of long-legged harvestmen, just to make sure that the Monoscutidae could be supported as monophyletic.

Which it couldn’t. When the results of the analysis came back to me, I saw that they had nested the South American Thrasychirus well within the Monoscutidae (everything from Spinicrus nigricans downwards in the tree above, reproduced from the paper, which is a consensus of a number of analyses done under varying parameters). Thrasychirus has not been previously regarded as a monoscutid, though Hunt & Cokendolpher (1991) had suggested that a relationship between the two was not outside the realms of possibility. Instead, Thrasychirus has been placed in the Enantiobuninae, treated as a subfamily of the family Neopilionidae. As well as the Enantiobuninae, Neopilionidae includes Neopilio australis, a species without close relatives from South Africa, and Ballarrinae, a group of tiny harvestmen with extraordinarily long palps found in Australia, South Africa and South America.

Male Forsteropsalis, probably F. inconstans, photographed by Alan Macdougall.

For a few reasons, I’m a little skeptical of the exact position of Thrasychirus in the above tree. The relationships between taxa were not strongly supported, and a couple of features of Thrasychirus look as if they may be consistent with a more basal position. Most notably, in most families of long-legged harvestmen the tarsus of each leg is divided into a basitarsus and distitarsus, with a distinct hinge allowing easy bending at the junction between the two. In most ‘Monoscutidae’, this hinge has disappeared and the junction between the two parts of the tarsus is fixed in a straight line. However, Thrasychirus (as well as Australiscutum) has a mobile hinge. However, whatever the exact position of Thrasychirus may turn out to be, I feel reasonably confident that the combination of ‘Monocutidae’ and Enantiobuninae will continue to be supported—in particular, the two share a unique spiracle morphology that has not been recorded from other families—and so I chose to recognise this clade as a single taxon. Enantiobuninae happens to be an older name than Monoscutidae, so it that was the name I had to use. In most analyses, this expanded Enantiobuninae was nested within a clade also including the other Neopilionidae*, so I chose to continue to treat Enantiobuninae as a subfamily of Neopilionidae.

*The exception was the analysis conducted with all characters given equal weighting, which gave some somewhat suspicious results (it failed to recover monophyly for some taxa that have been universally accepted in the past). It is my suspicion that these odd results were mainly due to the single included example of Ballarrinae; ballarrines have some features convergent with the Dyspnoi, another group of harvestmen, and these characters tended to pull the ballarrine towards the Dyspnoi. I have a manuscript currently in preparation that indicates that these unexpected results disappear as more taxa are included in the analysis.

The holotype of Hypomegalopsalis tanisphyros.

Most other results in the paper are reasonably straightforward. The genus Megalopsalis as recognised to date appears to be polyphyletic; in particular, the New Zealand species previously included in that genus have been moved to a new genus, Forsteropsalis, and are probably more closely related to other New Zealand enantiobunines in the genus Pantopsalis. The Western Australian Megalopsalis linnaei, a definite oddball among the Enantiobuninae, also gets its own genus Tercentenarium. And another new Western Australian species gets its own new genus in Hypomegalopsalis tanisphyros.

Let me be up front and say that I do not regard the establishment of Hypomegalopsalis as one of my greatest achievements. One of the failings of the binomial system of nomenclature, in my opinion, is that it doesn’t really allow for uncertainty. Including a new species in a pre-existing genus effectively makes a statement that that species is more closely related to the members of that genus than any other. On the other hand, many taxonomists would see the erection of a new genus as a statement that its member(s) are significantly different from those of pre-existing genera. In the case of tanisphyros, my initial expectation was that it would turn out to be a small species of Megalopsalis. However, none of the analyses I conducted supported such a clade. To include tanisphyros in Megalopsalis and keep the genus supported as monophyletic, I would have probably had to also include the heavily sclerotised species previously included in the ‘Monoscutinae’, which would have made the single genus Megalopsalis more morphologically disparate than probably the entire remaining Phalangioidea. If it was possible to describe a new species without placing it in a genus, I would have done so for tanisphyros, but the binomial system does not allow for such things. Placing it in a separate genus seemed the least objectionable option. Still, if anyone conducts a further study in the future that supports quashing Hypomegalopsalis, I won’t be protesting.

The saga of Forsteropsalis fabulosa
Published 21 February 2012
Male of Forsteropsalis fabulosa, copyright Danilo Hegg.

Technically, I had a paper last week. I say ‘technically’ because, at only one page long (excluding bibliography), I don’t that it counts much in the grand scheme of things. This commentary might be longer than the paper itself. Still, in its own way, this is a resolution for something that’s been hanging over me for the last ten years.

The article, published in Zootaxa, is titled Clarification of the type status of Macropsalis fabulosa Phillipps & Grimmett 1932. Macropsalis fabulosa is the harvestman species that currently goes by the name of Forsteropsalis fabulosa. It is one of the largest of New Zealand’s harvestmen, with a body length (excluding legs and chelicerae) a little shy of a centimetre (Phillipps & Grimmett 1932). As you can see in the photo at the top of this post, the male has chelicerae that are massively enlarged even by the standards of the group that it belongs to. The second inflated segment of the chelicera is about as large as the main body of the animal!

When I looked at all the (available) type specimens of New Zealand Enantiobuninae for my Master of Science thesis back in 2001, I discovered a problem with the type specimen of M. fabulosa. When a new species is described, the specimen(s) on which the description is based becomes the holotype (if a single specimen is used or designated) or the syntypes (if there is more than one specimen). However, sometimes the original type material of a species may become unavailable: it may be lost, destroyed, or subsequent researchers may not be able to identify what specimens the original author was using. In these cases, it may be necessary for an author to designate a neotype, a replacement type specimen. This is what had happened for M. fabulosa: Ray Forster had designated a neotype for it in 1944 because the original holotype had been destroyed. However, when I looked at Forster’s neotype and compared it with the illustration of the holotype in Phillipps & Grimmett’s original description, I realised that the two were not the same species! Here is the neotype, taken from the Te Papa online collection:

Compare the size and shape of the cheliceral fingers in that photo to the one at the top of this post. Also, while it is not clear in the photo, the neotype has a heavy covering of small spines over the top of the prosoma (cephalothorax), but Phillipps & Grimmett had specifically noted that, despite its size, M. fabulosa had a prosoma devoid of spines.

This raised a problem: should the name ‘Macropsalis fabulosa‘ be applied to the species represented in the original description, or to the species represented by the neotype? My own preference was towards the former option:

(1) Despite his choice of neotype, Forster (1944) had still maintained the characters of the original holotype in his verbal description of M. fabulosa. It is quite possible that his choice of neotype was a mistake.

(2) The neotype belonged to a named species, currently known as Forsteropsalis inconstans. Because fabulosa is an older name than inconstans, associating fabulosa with the neotype would mean that F. inconstans would have to be called F. fabulosa, while F. fabulosa would be unnamed.

However, to keep the name fabulosa with the original species would require replacing the neotype, and that is something that only the ICZN can do. So last year, myself and my supervisor at the Western Australian Museum, Mark Harvey, drafted an application to the ICZN asking that the neotype of M. fabulosa be replaced with one of the specimens I had attributed to that species in last year’s paper on Forsteropsalis (Taylor 2011). The application was duly submitted, but returned a few weeks later with explanations from the commissioners who had reviewed it that the ICZN would not be considering this case. Because they didn’t need to.

The ICZN, in its current form, has rather stringent requirements for establishing a neotype. Basically, you cannot designate a neotype for a species solely because it doesn’t have a holotype. There has to be an actual need for one, i.e. the species would not be properly identifiable without one. You also have to demonstrate that you took all the steps you could to make sure that the original holotype is honestly, truly lost (many specimens, for instance, may end up in a different museum from the one that the original author said they were in). Forster hadn’t done that, and he had also violated the requirements by selecting a specimen that didn’t match the diagnostic features of the species. So, according to the commissioners, there was no need to ask the ICZN to replace Forster’s neotype because it wasn’t valid in the first place.

But without the ‘neotype’ to confuse matters, there was no need for me to designate a new neotype either. Phillips & Grimmett’s original description is quite adequate to identify M. fabulosa (that was how I had identified specimens of it myself). So, after that long process, I end up writing an article explaining why I have nothing to explain. One interesting potential side-effect is that (as one of the commissioners explicitly noted) this case is not unusual: so stringent are the current requirements for neotypification, without any protection for past practices, that probably a great many past neotype designations are technically invalid. However, they remain unchallenged because, in the vast majority of cases, there is no actual need for a neotype.

More on the New Zealand Opiliones
Published 5 February 2013
Male of Pantopsalis listeri, photographed by Simon Pollard, used with permission in Taylor (2013).

New paper published today! Hurrah! Except I’ve already had it pointed out to me that the species descriptions are missing the type depository, and one of the new species names has been mis-spelt in a couple of places. So I must shamefacedly prepare myself a correction…

The paper in question is titled ‘Further notes on New Zealand Enantiobuninae (Opiliones, Neopilionidae), with the description of a new genus and two new species‘. It’s been published in ZooKeys, so it’s freely available online at the link just given. As well as the two new species of harvestmen mentioned in the title, the paper also does something that I personally am even more pleased with: it manages to make two nomina dubia not dubia any more!

It started with my own private little eureka moment. A few months back, I was looking through some of the New Zealand harvestmen material that’s been waiting for me to examine it. I pulled out one of the specimens and looked at it under the microscope. And as soon as I looked at it, I somehow had a thought pop into my mind: “That’s Pantopsalis cheliferoides“. Pantopsalis cheliferoides, I hasten to explain, is a species that was first described in 1882 by William Colenso, a missionary based in Ahuriri in Hawke’s Bay. Colenso was a fascinating character, living with one hand firmly on the Bible and the other up a native girl’s skirt (he was dismissed from the church in 1852 after fathering a child by his wife’s maid, and not readmitted to its services until 1894). He produced the first book to be printed in New Zealand, and was the first to translate the Bible into Maori. He was also a keen natural historian, particularly interested in botany. His endeavours in zoology were perhaps a little less sure: when he collected the first specimens of P. cheliferoides, he doesn’t seem to have been entirely sure if he was looking at a harvestman, a whip-spider, or a pseudoscorpion, so he kind of hedged his bets in giving it the name of Phalangium (Phrynus) cheliferoides. Unfortunately, P. cheliferoides then became something of a footnote in New Zealand arachnology. I had looked at the type specimen previously, but it wasn’t enough for me to be sure of it’s identity (and at the time, I was still a student and not confident enough to perform a genitalia dissection on a holotype). But it was enough that, when I came across more specimens of the species, I was able to recognise them for what they were. Hopefully, this will lift the animal that Colenso spent so much time trying to identify* out from its obscurity.

*In Colenso’s own words: “I have only seen four specimens in the woods, throughout three years, although from my first seeing one in 1879 (which I failed to capture), I have sought most diligently for specimens. In the following year I accidentally, and most unexpectedly, saw another in the same forest, and though I tried long and arduously to secure it without smashing, I failed to do so; it spread out its long flexible legs so prodigiously, that in the end it escaped among the thick vegetation” (Colenso 1882).

Male Pantopsalis cheliferoides, from Taylor (2013).

The other nomen ex-dubium dealt with in the paper is arguably even more important, as it is the type species of the genus Pantopsalis. This species was first described as Phalangium listeri by A. White back in 1849, in about three lines of text that are completely inadequate to recognise the species in question (with no further locality data given than ‘New Zealand’), and the type specimen(s) seem to have since been lost. The species was redescribed by the French arch-arachnologist Eugene Simon in 1879, who placed it in the new genus Pantopsalis. Recently, I was able to borrow Simon’s P. listeri specimens from the Muséum national d’Histoire naturelle in Paris; as it turns out, they belong to the same species that I had dealt with in 2004 under the name of Pantopsalis luna. Because the original type was lost, I’ve designated one of the Paris specimens as the neotype for P. listeri. It isn’t entirely certain that Simon was actually looking at the same species as White had been (indeed, as mentioned in the paper, there’s some cause to believe he wasn’t). But everyone since Simon has followed his lead on the identity of Pantopsalis, and naming one of his specimens as neotype has the advantage of confirming the status quo.

Male of Mangatangi parvum, from Taylor (2013).

The two new species in the paper are Forsteropsalis pureora (as it should have been throughout, dammit) and Mangatangi parvum. The latter species is particularly neat: it’s very small compared to some of the other long-legged harvestmen in New Zealand, and certain features suggest that it may represent the sister taxon to the clade containing the genera Pantopsalis and Forsteropsalis. I’m still doing some work to try and test that.

Bye, bye, Spinicrus
Published 5 September 2013
Female Spinicrus…no, sorry, Megalopsalis nigricans, photographed by Tony.

I’ve just had a paper out. The funny thing is, it’s making me feel both pleased yet a little maudlin, because it represents something of an end of an era. The last part of my PhD thesis has been published. The last remnant of my student days has been cast off. I think I need a hug.

The paper in question is: Taylor, C. K. 2013. Further revision of the genus Megalopsalis (Opiliones, Neopilionidae), with the description of seven new species. ZooKeys 328: 59–117. It’s open access, so go take a squizz. One thing that I also can’t resist pointing out, though I don’t know if it really makes much difference because it’s a primarily online journal and hardly anyone will see the print issue: it’s one of my images on the cover.

Technically, this paper represents my long-awaited (by me, at least) revision of the harvestman genus Spinicrus. In the end, though, I had to change the title of the paper, because on of the main results of this revision was that Spinicrus became a synonym of the older genus Megalopsalis. In an earlier publication, I cut Megalopsalis down to size by removing its New Zealand species to a new genus, Forsteropsalis. But now it’s back, and stronger than ever before!

Female Megalopsalis tasmanica, the erstwhile Spinicrus tasmanicum. Another photograph from Tony.

Previously, Spinicrus was primarily separated from Megalopsalis by one feature: the presence of a side branch on one of the segments of the pedipalps of Megalopsalis. Taxonomists tend to be wary of defining a group purely by the absence of features. It implies that the members of that group are united more by the idea that they just don’t belong in any other group, rather than anything that actually connects them per se. So, in this case, Megalopsalis was the species with a pedipalp side-branch, and Spinicrus was… the rest. It also didn’t help matters that a pedipalp side-branch is something that has evolved and de-evolved a number of times within harvestmen, leading to a bit of questioning about its significance. A few years ago, I separated a few of the more distinctive ‘Spinicrus’ as the genus Neopantopsalis. This made Spinicrus a bit less heterogeneous but still didn’t solve the underlying issue. It just meant that now you took out Megalopsalis and took out Neopantopsalis, and Spinicrus was still… the rest.

The answer, as so often in invertebrate taxonomy, came largely from the boy bits. When I looked at the male genitalia, I found that Megalopsalis and Spinicrus species shared a similar penis morphology, in which the end of the penis was fairly short, flat and shaped more or less like a rounded triangle:

This is what a ‘Spinicrus’ stewarti penis looks like.

In contrast, the end of the penis in Neopantopsalis species is longer, as demonstrated by N. thaumatopoios:

Put these features into a phylogeny of the family that these genera belong to (Neopilionidae), and I overall ended up with this:

Consensus of various phylogenetic analyses under various parameters (numbers at nodes represent the percentage of analyses in which that clade was recovered). Taxa coloured green are what would have been called ‘Spinicrus’ previously, while those in red would have been ‘Megalopsalis’.

Note that this is a bit of a faux phylogeny, because it’s a comparative summary of separate analyses under separate parameters (see the paper for details). Only those clades marked with a 100 were supported in all analyses. The important detail is the distribution of the green ‘Spinicrus’ relative to the red ‘Megalopsalis’: no matter what the analytical conditions, ‘Megalopsalis’ was always nested well within ‘Spinicrus’. Indeed, under most conditions, ‘Megalopsalis’ was polyphyletic within ‘Spinicrus’. Because of this, and because of the lack of any positive uniting features for Spinicrus species that were not also present in Megalopsalis, I felt the best course of action was to declare the two genera synonyms. Also subsumed under Megalopsalis was Hypomegalopsalis, a species that I had earlier established for a single species of uncertain affinities (Megalopsalis tanisphyros in the tree above). At the time, I commented that, “if anyone conducts a further study in the future that supports quashing Hypomegalopsalis, I won’t be protesting”. The fact that I got to do that myself just makes me all the happier.

There’s a lot more I could talk about here, but I’m sure you all stopped reading long ago. Just go to the paper.

The eater of light
Published 19 August 2014
The Waitomo harvestman Forsteropsalis photophaga, from Taylor & Probert (2014).

A little less than a year ago, I was contacted by a student at the University of Auckland in New Zealand, asking me about some harvestmen that she’d been trying to identify me from the Waitomo cave system. This incited a certain degree of excitement on my part, because I was not entirely unfamiliar with Waitomo’s harvestmen. I had first seen specimens from there while doing my MSc back in 2001 or 2002, and had realised then that they represented an undescribed species. However, for various reasons, I had not yet published a description of the species in question. So when Anna contacted me, I decided it was time to bump the Waitomo harvestmen up the to-do list, and I replied to her asking if she would be interested in collaborating on a paper on the Waitomo harvestmen. She agreed, and the resulting paper came out just last week: C. K. Taylor & A. Probert, “Two new species of harvestmen (Opiliones, Eupnoi, Neopilionidae) from Waitomo, New Zealand”.

Image of Waitomo cave, from here.

The Waitomo caves may be the world’s only tourist attraction centred around an infestation of flies. The caves are home to an abundant population of glow-worms, larvae of the fungus gnat Arachnocampa luminosa. These fly larvae live on the roof of the cave, held in place by a silken hammock, and produce spots of brilliant blue light. It is the spectacle of these lights that draw the tourists, but for the glow-worms they serve a different purpose: the lights attract insects flying in the cave. In flying towards the light, insects become entangled in sticky threads that each glow-worm suspends below its hammock, providing the glow-worm with food. You can see a video of the process here, taken from the BBC’s Planet Earth series.

But the glow-worms are not without predators of their own. With their long slender legs, harvestmen are able to carefully tip-toe between the sticky threads and pluck out the glow-worms, as from a luminous buffet (they also eat them at the pupal and adult stages). The harvestmen of Waitomo were studied by Myer-Rochow & Liddle (1988), who identified two species. One, a ‘short-legged harvestman’ Hendea myersi cavernicola (which actually has decidedly long legs, natch), is endemic to the cave system and was identified by Meyer-Rochow and Liddle as a strict troglobite (i.e. it spends its entire life within the cave). It has a number of features commonly associated with cave-dwelling, such as pale coloration and lengthened legs. It does differ from most troglobites in that it is not blind: while its eyesight is dim, it does retain enough to find its glowing prey.

Meyer-Rochow and Liddle also identified a ‘long-legged harvestman’ in the Waitomo caves, which they referred to as ‘Megalopsalis tumida‘. This name refers to a species first described from Wellington, quite some distance to the south, that now goes by the name of Forsteropsalis fabulosa. As it turns out, I identified two species of Forsteropsalis in material from the caves, neither of which was F. fabulosa. I can’t be certain which was the species being looked at by Meyer-Rochow and Liddle. For various reasons, I suspect that they may have been looking at examples of both, but, as I’ve never been able to locate any vouchers for their study, I can’t really say (remember, kids, vouchers are important).

Forsteropsalis bona, from Taylor & Probert (2014).

One of these species is indeed very similar to Forsteropsalis fabulosa, and has accordingly been labelled Forsteropsalis bona. Indeed, the two species are similar enough that I can now see that the photograph I used in my earlier post to illustrate F. fabulosa in fact shows an individual of F. bona. The primary difference between the two is in their pedipalps: in F. fabulosa, the patella of the pedipalp has a distinct finger-like process that is much reduced in F. bona. Forsteropsalis bona is not a strict troglobite: specimens have been collected at Waitomo both inside and outside the cave entrance. Instead, it is what is called a troglophile: individuals of F. bona probably use the caves as a cool, damp place to hang out during the day, emerging to forage outside the cave at night. This is the same pattern of behaviour found in New Zealand’s cave wetas.

The second species is the beauty pictured at the top of this post. Its species name, photophaga, means ‘eater of light’, referring of course to its probable predation on glow-worms. This is a stunning animal: the enormous chelicerae typical of New Zealand Neopilionidae are rendered even more eye-catching by the presence of rows of longer spines (offhand, we don’t yet know what the females of either of the Waitomo species look like, but they probably resemble other Forsteropsalis females in lacking the long chelicerae of the males). Whether Forsteropsalis photophaga is a troglobite or a troglophile is a bit more uncertain. I’m not aware of it having ever been collected outside the caves, but it doesn’t seem to have the obvious modifications for cave-dwelling of Hendea myersi cavernicola (though when t comes to assessing elongated limbs in what is already a long-legged harvestman… how are you going to tell?). At present, I’m guessing troglophile rather than troglobite, but future studies may easily prove me wrong.

Forsteropsalis photophaga is also an intriguing animal from a taxonomic viewpoint. In the past, the two New Zealand harvestman genera Pantopsalis and Forsteropsalis have been pretty easy to distinguish, but F. photophaga has some features that are more reminiscent of Pantopsalis than of Forsteropsalis. Recently, other things have been brought to my attention that suggest that, while Pantopsalis as we currently know it still seems fairly robust, Forsteropsalis is beginning to look decidedly fuzzy around the edges. The relationship between these two genera (if, indeed, they should still be recognised as two separate genera) has still not been resolutely ironed out.

Systematics of Neopilionidae

Characters (from Taylor 2011): Dorsum of opisthosoma usually coriaceous, rarely sclerotised. Glans of penis lacking lateral setae; lateral processes often present at shaft-glans junction. Spiracle lacking entapophysis, often with occluding spines. Pedipalp small, leg-like, without large spinose setae; tarsus longer than tibia.

<==Neopilionidae [Enantiobuninae, Megalopsalidinae, Megalopsalinae, Monoscutidae]T11
    |--+--Thrasychirus Simon 1884GS21, T11 [incl. Enantiobunus Mello-Leitão 1931T11]
    |  |    |--*T. dentichelis Simon 1884C92
    |  |    |--T. gulosus Simon 1884T11 [incl. *Enantiobunus spinulosus Mello-Leitão 1931C92]
    |  |    `--T. modestus Simon 1902R23
    |  `--Thrasychiroides Soares & Soares 1947P-RBT14
    |       |--*T. brasilicus Soares & Soares 1947C92
    |       |--T. moporanga Pinto-da-Rocha, Bragagnolo & Tourinho 2014P-RBT14
    |       |--T. toryba Pinto-da-Rocha, Bragagnolo & Tourinho 2014P-RBT14
    |       `--T. ybytyra Pinto-da-Rocha, Bragagnolo & Tourinho 2014P-RBT14
    `--+--+--Neopilio Lawrence 1931T13b, T11 [Neopilioninae]
       |  |    |--*N. australis Lawrence 1931C92
       |  |    `--N. inferi Lotz 2011L11
       |  `--BallarrinaeGS21
       `--+--Australiscutum Taylor 2009T13b, T11
          |    |--*A. hunti Taylor 2009T09, T11
          |    `--+--A. graciliforceps Taylor 2009T11
          |       `--A. triplodaemon Taylor 2009T11
          |--Martensopsalis Giribet & Baker in Giribet, Baker & Brouste 2021GBB21
          |    `--*M. dogny Giribet & Baker in Giribet, Baker & Brouste 2021GBB21
          `--+--Megalopsalis Roewer 1923GS21, T13b (see below for synonymy)
             |    |  i. s.: M. thryptica (Hickman 1957)T13b [=Spinicrus thrypticumT13b, S. thrypticus (l. c.)T04]
             |    |--M. nigricans (Hickman 1957)GS21, T13b [=Spinicrus nigricansT13b]
             |    `--+--+--M. suffugiens Taylor 2013T13b
             |       |  `--+--M. minima (Kauri 1954) [=Spinicrus minimum, S. minimus]T13b
             |       |     `--+--M. porongorupensis (Kauri 1954) [=Spinicrus porongorupense, S. porongorupensis]T13b
             |       |        `--M. walpolensis Taylor 2013T13b
             |       `--+--M. coronata Taylor 2013T13b
             |          `--+--+--M. caeruleomontium Taylor 2013T13b
             |             |  `--+--M. atrocidiana Taylor 2013T13b
             |             |     `--M. puerilis Taylor 2013T13b
             |             `--+--+--M. leptekes Taylor 2011T13b
             |                |  `--M. tanisphyros (Taylor 2011)T13b [=*Hypomegalopsalis tanisphyrosT11]
             |                `--+--+--M. sublucens Taylor 2013T13b
             |                   |  `--M. tasmanica (Hogg 1910)GS21, T13b (see below for synonymy)
             |                   `--+--+--M. stewarti (Forster 1949)GS21, T13b [=Spinicrus stewartiT13b]
             |                      |  `--+--M. hoggi (Pocock 1903) [=Macropsalis hoggi]T11
             |                      |     `--+--M. pilliga Taylor 2011T11
             |                      |        `--+--M. epizephyros Taylor 2011T11
             |                      |           `--+--*M. serritarsus (Sørensen 1886) [=*Macropsalis serritarsus]T11
             |                      |              `--M. eremiotis Taylor 2011T11
             |                      `--Neopantopsalis Taylor & Hunt 2009GS21, T13b
             |                           |  i. s.: N. continentalis (Roewer 1923)T11 (see below for synonymy)
             |                           |--+--*N. quasimodo Taylor & Hunt 2009TH09, T13b
             |                           |  `--N. pentheter Taylor & Hunt 2009T13b, TH09
             |                           `--+--N. psile Taylor & Hunt 2009T11
             |                              `--+--N. camelus (Forster 1949)T11 [=Spinicrus camelusTH09]
             |                                 `--N. thaumatopoios Taylor & Hunt 2009T11
            `--+--+--Mangatangi Taylor 2013GS21, FVG14
               |  |    `--*M. parvum Taylor 2013T13a
               |  `--+--Tercentenarium Taylor 2011T11
               |     |    `--*T. linnaei (Taylor 2008) [=Megalopsalis linnaei]T11
               |     `--MonoscutinaeT11
               |          |  i. s.: Acihasta Forster 1948T08
               |          |           `--*A. salebrosa Forster 1948T08
               |          |--+--‘Megalopsalis’ triascuta Forster 1944GS21, T11
               |          |  `--Monoscutum Forster 1948GS21, T09
               |          |       `--*M. titirangiense Forster 1948 [=M. titirangiensis]T08
               |          `--Templar Taylor 2008GBB21, T08
               |               `--*T. incongruens Taylor 2008T08
               `--+--Forsteropsalis Taylor 2011GS21, T11
                  |    |  i. s.: F. distincta (Forster 1964) [=Pantopsalis distincta, Megalopsalis distincta]T11
                  |    |         F. grayi (Hogg 1920) [=Pantopsalis grayi, Megalopsalis grayi]T11
                  |    |--F. turneri (Marples 1944)GS21 [=Megalopsalis turneriFVG14, Macropsalis turneriF44]
                  |    `--+--+--F. bona Taylor & Probert 2014GS21, TP14
                  |       |  `--F. photophaga Taylor & Probert 2014GS21, TP14
                  |       `--+--F. inconstans (Forster 1944)GS21, T11 (see below for synonymy)
                  |          `--+--F. fabulosa (Phillipps & Grimmett 1932)GS21, T11 (see below for synonymy)
                  |             `--+--*F. chiltoni (Hogg 1910)T11, GS21, T11 [=Macropsalis chiltoniT11, Megalopsalis chiltoniT11]
                  |                `--F. marplesi (Forster 1944)FVG14, T11 [=Megalopsalis marplesiT11]
                  `--+--+--‘Forsteropsalis’ pureora Taylor 2013GS21, FVG14 [=F. pureroaT13a]
                     |  `--‘Forsteropsalis’ wattsi (Hogg 1920)FVG14 [=Pantopsalis wattsiT11, Megalopsalis wattsiT11]
                     `--+--‘Forsteropsalis’ grimmetti (Forster 1944)GS21, T11 [=Megalopsalis grimmettiT11]
                        `--Pantopsalis Simon 1879GS21, T11
                             |  i. s.: P. halli Hogg 1920T04
                             |         P. johnsi Forster 1964 [incl. P. mila Forster 1964]T04
                             |         P. pococki Hogg 1920T04
                             |         P. rennelli Forster 1964T04
                             |--P. snaresensis Forster 1964GS21, FVG14
                             `--+--+--*P. listeri (White 1849)T13a, GS21, T13a (see below for synonymy)
                                |  `--P. cheliferoides (Colenso 1882)FVG14 [=Phalangium (Phrynus) cheliferoidesT04]
                                `--+--P. albipalpis Pocock 1903GS21, T11 (see below for synonymy)
                                   |--P. coronata Pocock 1903GS21, T04 [incl. P. trippi Pocock 1903T04]
                                   `--P. phocator Taylor 2004FVG14

Forsteropsalis fabulosa (Phillipps & Grimmett 1932)GS21, T11 [=Macropsalis fabulosaT11, Megalopsalis fabulosaT11; incl. Me. tumida Forster 1944TP14, Forsteropsalis tumidaT11]

Forsteropsalis inconstans (Forster 1944)GS21, T11 [=Megalopsalis inconstansT11; incl. M. chiltoni nigra Forster 1944FVG14, Forsteropsalis nigraFVG14]

Megalopsalis Roewer 1923GBB21, T13b [=Macropsalis Sørensen 1886 non Sclater 1866T13b; incl. Hypomegalopsalis Taylor 2011T13b, Spinicrus Forster 1949T13b]

Megalopsalis tasmanica (Hogg 1910)GS21, T13b [=Pantopsalis tasmanicaT04, *Spinicrus tasmanicumC92, S. tasmanicus (l. c.)T04]

Neopantopsalis continentalis (Roewer 1923)T11 [=Pantopsalis continentalisTH09, Spinicrus continentaleTH09]

Pantopsalis albipalpis Pocock 1903GS21, T11 [incl. P. jenningsi Pocock 1903T04, P. nigripalpis Pocock 1902T04, P. nigripalpis spiculosa Pocock 1902T04, P. nigripalpis spinulosa (l. c.)T04]

*Pantopsalis listeri (White 1849)T13a, GS21, T13a [=Phalangium listeriT13a; incl. Megalopsalis luna Forster 1944T13a, Pantopsalis lunaT13a]

*Type species of generic name indicated


Colenso, W. 1882. On some newly-discovered New Zealand arachnids. Transactions and Proceedings of the New Zealand Institute 15: 165–173.

[C92] Crawford, R. L. 1992. Catalogue of the genera and type species of the harvestman superfamily Phalangioidea (Arachnida). Burke Museum Contributions in Anthropology and Natural History 8: 1–60.

[FVG14] Fernández, R., S. Vélez & G. Giribet. 2014. Linking genetic diversity and morphological disparity: biodiversity assessment of a highly unexplored family of harvestmen (Arachnida: Opiliones: Neopilionidae) in New Zealand. Invertebrate Systematics 28: 590–604.

[F44] Forster, R. R. 1944. The genus Megalopsalis Roewer in New Zealand with keys to the New Zealand genera of Opiliones. Records of the Dominion Museum 1 (1): 183–192.

[GBB21] Giribet, G., C. M. Baker & D. Brouste. 2021. Martensopsalis, a new genus of Neopilionidae from New Caledonia (Opiliones: Eupnoi). Zootaxa 4984 (1): 98–107.

[GS21] Giribet, G., K. Sheridan, C. M. Baker, C. J. Painting, G. I. Holwell, P. J. Sirvid & G. Hormiga. 2021. A molecular phylogeny of the circum-Antarctic Opiliones family Neopilionidae. Invertebrate Systematics 35: 827–849.

Hunt, G. S., & J. C. Cokendolpher. 1991. Ballarrinae, a new subfamily of harvestmen from the Southern Hemisphere. Records of the Australian Museum 43: 131–169.

[L11] Lotz, L. N. 2011. Three new harvestmen species from southern Africa (Arachnida: Opiliones: Caddidae, Neopilionidae, Assamiidae). Journal of Afrotropical Zoology 7: 3–8.

Meyer-Rochow, V. B., & A. R. Liddle. 1988. Structure and function of the eyes of two species of opilionid from New Zealand glow-worm caves (Megalopsalis tumida: Palpatores, and Hendea myersi cavernicola: Laniatores). Proceedings of the Royal Society of London Series B (Biological Sciences) 233: 293–319.

Phillipps, W. J., & R. E. R. Grimmett. 1932. Some new Opiliones from New Zealand. Proceedings of the Zoological Society of London 1932: 731–740.

[R23] Roewer, C.-F. 1923. Die Weberknechte der Erde: Systematische Bearbeitung der bisher bekannnten Opiliones. Gustav Fischer: Jena.

[T04] Taylor, C. K. 2004. New Zealand harvestmen of the subfamily Megalopsalidinae (Opiliones: Monoscutidae)—the genus Pantopsalis. Tuhinga 15: 53–76.

[T08] Taylor, C. K. 2008. A new species of Monoscutinae (Arachnida, Opiliones, Monoscutidae) from New Zealand, with a redescription of Monoscutum titirangiense. Journal of Arachnology 36: 176–179.

[T09] Taylor, C. K. 2009. Australiscutum, a new genus of Monoscutidae (Arachnida: Opiliones) from eastern Australia, with the first record of asymmetrical chelicerae in Opiliones. Insect Systematics and Evolution 40: 319–332.

[T11] Taylor, C. K. 2011. Revision of the genus Megalopsalis (Arachnida: Opiliones: Phalangioidea) in Australia and New Zealand and implications for phalangioid classification. Zootaxa 2773: 1–65.

[T13a] Taylor, C. K. 2013a. Further notes on New Zealand Enantiobuninae (Opiliones, Neopilionidae), with the description of a new genus and two new species. ZooKeys 263: 59–73.

[T13b] Taylor, C. K. 2013b. Further revision of the genus Megalopsalis (Opiliones, Neopilionidae), with the description of seven new species. ZooKeys 328: 59–117.

[TH09] Taylor, C. K., & G. S. Hunt. 2009. New genus of Megalopsalidinae (Arachnida: Opiliones: Monoscutidae) from north-eastern Australia. Zootaxa 2130: 41–59.

[TP14] Taylor, C. K., & A. Probert. 2014. Two new species of harvestmen (Opiliones, Eupnoi, Neopilionidae) from Waitomo, New Zealand. ZooKeys 434: 37–45.

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