Tetrapod Zoology

Ermentrude the liolaemine

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Thank you and well done to everyone who had a bash at identifying Ermentrude. For the most part, you were correct: Ermentrude was indeed an iguanian, and within Iguania a tropidurid… or tropidurine… I mean liolaemid… or liolaemine, or liolaemin.. and, within that group, a species of the large South American taxon Liolaemus. What species? Well, that’s a bit trickier to answer…

An average of about four new Liolaemus species are described every year, and there are currently around 200 species*, so it can be difficult to keep track of them. Ermentrude was labelled as a ‘spotted swift’ when I bought him: swifts are a mostly North American group of phrynosomatid iguanians, many of which are good at climbing (some are called fence lizards for this reason).

* It is thought by some that the genus will eventually exceed other particularly speciose iguanian groups, like Anolis (sensu lato!).

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However, swifts tend to have pointed, keeled scales on their dorsal and lateral surfaces (and hence are often called spiny lizards) and many species sport bold longitudinal or transverse stripes, chevrons, or collars. Ermentrude just didn’t match any of that, so I always thought the swift identification was wrong. So, more recently, I had decided that he was a species of Liolaemus, with the Chilean species L. nigroviridis being a reasonable guess (but not necessarily the right one). I asked Richard Etheridge, a herpetologist who has published a lot on these lizards, and this was his best guess too [adjacent image shows Yarrow’s spiny lizard Sceloporus jarrovi of southwestern USA and Mexico].

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Liolaemus is a pretty interesting taxon (hey: just like all the others!). Occurring in South America from the Pacific to Atlantic coasts, and from Peru to Tierra del Fuego, its diversification appears to have occurred in the Andean and/or Patagonian highlands (Schulte et al. 2000). Unlike a few other iguanian clades (like the Australian dragons and anoles), diversification within the group has apparently been slow and steady, rather than short and rapid (Harmon et al. 2003). While mostly inhabiting high altitudes, Liolaemus species dominate the scrubland lizard faunas of southern South America and in Chile it is typical to find four species partitioning the same habitat. Several species inhabit beaches and L. lutzae [shown in adjacent image] is restricted to the beaches of Rio de Janeiro. It is omnivorous, if not predominantly herbivorous as an adult (Rocha 1989, 1999), and has been very much affected by human development of its habitat. Some species inhabit places with strongly seasonal climates and can cope with very cold winters, and indeed L. magellanicus of Tierra del Fuego is the most southerly occurring lizard in the world.

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The adaptive value of viviparity in Liolaemus has been studied: viviparity has repeatedly evolved within the group, occurring in those high-altitude and/or high latitude taxa that have larger bodies (Cei et al. 2003). At least one Liolaemus species is parthenogenetic, meaning that this trait has evolved in iguanians as well as in most other squamate lineages. One subject which has been discussed quite a lot in lizards concerns which correlations, if any, occur between morphology and mode of life, with some studies on some groups finding no obvious correlations at all. Indeed some workers have reported exactly this for Liolaemus (Jaksic et al. 1980). Schulte et al. (2004) did further work of this sort on Liolaemus and found that different species had different escape strategies, and it was these escape strategies that tied to morphological differences [adjacent image show a member of the Patagonian L. elongatus species complex].

Paradoxical herbivory

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Among the liolaemids, Ctenoblepharys is insectivorous, but Phymaturus is entirely herbivorous and Liolaemus includes insectivores, omnivores and herbivores [Phymaturus shown in adjacent image: picture borrowed from Wiens lab page]. The widespread herbivory that occurs among Liolaemus is not well known and indeed has been repeatedly missed or ignored in reviews of reptilian herbivory. Espinoza et al. (2004) drew attention to the fact that, contrary to predictions made on the basis of other herbivorous lizards (most of which are large, live in warm places and maintain high body temperatures), herbivory had repeatedly evolved at small body size and in cool-climate Liolaemus species: in fact, herbivory has probably evolved more times within Liolaemus than it has within any other group of squamates, and about 66 times more rapidly than it has in non-liolaemid squamates (Espinoza et al. 2004, p. 16823).

As I noted previously, Ermentrude really loved banana and would do anything to get it, but I can’t recall him eating other plant material. He liked egg but failed to eat any bit of a pinky (that’s a dead baby mouse for those of you unfamiliar with reptile keeping). Among arthropods, he was particularly fond of woodlouse, mealworms, wolf spiders and baby stick insects. Never touched crickets.

The scattering to the winds of Iguanidae… or not

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Like most modern people interested in herpetology, I grew up with the idea that iguana-type lizards (the term Iguania wasn’t used much in them days) could be grouped into Iguanidae, Agamidae and Chamaeleonidae. So much has changed since then. Frost & Etheridge (1989) really kicked things off by bringing attention to the fact that no evidence for the monophyly of Iguanidae (sensu lato) had ever been presented (this is a recurring problem with lots of taxonomically inclusive groups, not only among squamates, but among living things in general); they started a trend by removing anoles and kin from ‘Iguanidae’ and calling them Polychrotidae. Frost et al. (2001) noted that ‘this approach met with some scepticism… but for the most part it was met with considerable enthusiasm and adopted wherever monophyly was taken seriously, which we were gratified to see was in most of the Western Hemisphere’ (p. 13) [ha! Take that Australasia! Joke].

More recent work has indicated that all of those iguanians once called iguanids can still be recognised as a clade – it can be called Pleurodonta Cope, 1864 – and it’s argued by some that the name Iguanidae is best restricted to the clade that includes Iguana and its close relatives. Frost et al. (2001) considered Pleurodonta to consist of Corytophanidae (basilisks, helmeted basilisks, coneheaded iguanas), Crotaphytidae (collared lizards, leopard lizards), Hoplocercidae (wood lizards and kin), Iguanidae (Galapagos iguanas, green iguanas, chuckwallas and kin), Leiocephalidae (curly-tailed lizards), Leiosauridae (leiosaurs, pristidactylines and kin), Liolaemidae (err, liolaemines), Opluridae (Malagasy iguanas), Phrynosomatidae (horned lizards, sand lizards, fence lizards and kin), Polychrotidae (anoles) and Tropiduridae (lava lizards, whorltail iguanas and kin)! However, not everyone agrees with this approach: Schulte et al. (2003) simply used Iguanidae instead of Pleurodonta, and regarded corytophanids and so on as iguanid ‘subfamilies’. It doesn’t really matter which system we use, but for the reason that ‘family’ and ‘subfamily’ ranks come loaded with preconceptions about diversity and phylogenetic distance I personally think that Frost et al.’s system is better [adjacent image shows the corytophanid, or corytophanine, Corytophanes cristatus].

For good, group-by-group coverage of all of these animals (many of which are obscure and little known), see Pianka & Vitt (2003). Hey, I’d cover them all myself, but not today…

Refs – –

Cei, J. M., Videla, F. & Vicente, L. 2003. From oviparity to viviparity: a preliminary note on the morphometric differentiation between oviparous and viviparous species assigned to the genus Liolaemus (Reptilia, Squamata, Liolaemidae). Journal of Zoological Systematics & Evolutionary Research 41, 152-156.

Espinoza, R. E., Wiens, J. J. & Tracy, C. R. 2004. Recurrent evolution of herbivory in small, cold-climate lizards: breaking the ecophysiological rules of reptilian herbivory. Proceedings of the National Academy of Sciences 101, 16819-16824.

Frost, D. R. & Etheridge, R. 1989. A phylogenetic analysis and taxonomy of iguanian lizards. University of Kansas Museum of Natural History, Miscellaneous Publications 81, 1-65.

– ., Etheridge, R., Janies, D. & Titus, T. A. 2001. Total evidence, sequence alignment, evolution of polychrotid lizards, and a reclassification of the Iguania (Squamata: Iguania). American Museum Novitates 3343, 1-38.

Harmon, L. J., Schulte, J. A., Larson, A. & Losos, J. B. 2003. Tempo and mode of evolutionary radiation in iguanian lizards. Science 301, 961-964.

Jaksic, F. M., Nez, H. & Ojeda, F. P. 1980. Body proportions, microhabitat selection, and adaptive radiation of Liolaemus lizards in central Chile. Oecologia 45, 178-181.

Pianka, E. R. & Vitt, L. J. 2003. Lizards: Windows to the Evolution of Diversity. University of California Press, Berkeley.

Rocha, C. F. D. da 1989. Diet of a tropical lizard (Liolaemus lutzae) of southeastern Brazil. Journal of Herpetology 23, 292-294.

– . 1999. Home range of the tropidurid lizard Liolaemus lutzae: sexual and body size differences. Revista Brasileira de Biologia 59, 125-130.

Schulte, J. A., Losos, J. B., Cruz, F. B. & Nez, H. 2004. The relationship between morphology, escape behaviour and microhabitat occupation in the lizard clade Liolaemus (Iguanidae: Tropidurinae: Liolaemini). Journal of Evolutionary Biology 17, 408-420.

– ., Macey, J. R., Espinoza, R. & Larson, A. 2000. Phylogenetic relationships in the iguanid lizard genus Liolaemus: multiple origins of viviparous reproduction and evidence for recurring Andean vicariance and dispersal. Biological Journal of the Linnean Society 69, 75-102.

– ., Valladares, J. P. & Larson, A. 2003. Phylogenetic relationships within Iguanidae using molecular and morphological data and a phylogenetic taxonomy of iguanian lizards. Herpetologica 59, 399-419.

Comments

  1. #1 Ethan Kocak
    February 28, 2008

    Growing up, I had a lizard just like the 2nd image in the post. It was sold to me only as a “Crevice spiny lizard,” and I really haven’t seen one in years. It too was extremely tame and would ride around in a pocket with me. It also had light blue markings on its belly.

    Anyway, love the blog, read it all the time.

  2. #2 John Conway
    February 28, 2008

    You’re wrong. It’s a ropen.

  3. #3 Sven DiMilo
    February 28, 2008

    Hee hee! I was thinking of Liolaemus when I guessed “tropidurine” (note the reference to herbivory), but I had forgottem that Frost et al. had elevated liolaemines to their own family…this is why we who study what animals do (as opposed to what they are) get pissed off at systematists. Tell me what to call the damn thing and I’ll call it that…but quit changing yer damn minds! (kidding, of course…progress of science and all that)

  4. #4 Darren Naish
    February 28, 2008

    John: when it’s a ropen, I’ll tell you it’s a ropen, ok?

    As for the common name mentioned by Ethan (for the sceloporine Sceloporus poinsettii), I’ve always tried to avoid using it: I just have an aversion to the word ‘crevice’. Even worse, you could get the order jumbled and end up saying ‘spiny crevice’. Sorry – it’s been a rough day :)

  5. #5 Ivy
    February 28, 2008

    His eyes gave it away. :) Nothing gives Stink Eye like an ig.

  6. #6 Zach Miller
    February 28, 2008

    Darren, now you have to do a post about chameleons. They are my favorite modern monkey-lizards!

  7. #7 Ethan Kocak
    February 28, 2008

    Wouldn’t want a lizard in ANY crevice–ESPECIALLY a spiny one. Ho ho.

  8. #8 Thylacine
    February 28, 2008

    I brushed one just like that off of my beer the other day.
    Florida is full of exotic reptiles now
    I saw a wild iguana in my bamboo a week ago.Any body know how far up the Florida coast the Nile Monitors have gotten so far? Last year I hit a python in Boca

  9. #9 Karl Zimmerman
    February 28, 2008

    Darren,

    Do you know if any of the herbivorous lizards in this clade are available as pets? Small, cold-tolerant, and not needing live insects makes them seem like the ideal pet for the more squeamish herp fan.

  10. #10 Ethan Kocak
    February 28, 2008

    @ Karl Zimmerman

    You should look into crested geckos (Rhacodactylus ciliatus). They can be kept at room temperature and fed a commercially available powder mixed with water. They’re also mild mannered and easily handled. And only rediscovered in 1994 after being thought extinct for a 100 years!

  11. #11 Doug M.
    February 29, 2008

    Herbivory has evolved multiple times in squamates… okay, but [stupid question here] are there any herbivorous snakes?

    I can’t think of any, and brief googling gives several hits for “there are no herbivorous snakes”. Still, zoology is full of surprises…

    But if not, then it would seem lizards can evolve secondary herbivory, but not snakes. Huh.

    Doug M.

  12. #12 neil
    February 29, 2008

    Aww now I feel like I really missed out. I wasn’t allowed a pet reptile due to the samonella risk. How long did you pet live darren?

  13. #13 Sven DiMilo
    February 29, 2008

    Hi Doug–yeah, huh. Not a single herbivorous snake. In fairness, “lizards” have been around a lot longer than snakes–which are actually just very specialized lizards. Specialized to eat relatively large prey, in most cases. So, starting off as a particularly carnivorous branch of lizards, it’s perhaps not so surprising that snakes have stuck uniformly to carnivory–the same could be said, actually, about most other squamate clades. True herbivory is still quite rare among lizards.

  14. #14 DouglasG
    February 29, 2008

    As an Green Iguana owner, I think it is often misconstrued that some lizards are not herbivorous. Since I have had my Iguana Hank (it has been 15 years now), he has never eaten any meat. I think it is often a misconception that some lizards are omnivorous or carnivorous. In fact, for many species, we just don’t know what they are eating. Many assume, it’s a lizard, thus it eats bugs. I think that it is a mistake to make such an assumption.

    Salmonella is only a problem if you do not wash your hands after handling the lizard. The salmonella live happily in the lizard digestive system, and it’ll only get into yours if you eat what was in their digestive system. How likely is that? Don’t eat their droppings, and you’ll be fine.

  15. #15 Sven DiMilo
    February 29, 2008

    DouglasG: Your Green iguana is one of the most specialized herbivores among lizards; this is well studied from ecological, physiological, morphological, and microbiological viewpoints. We have a pretty good idea about what almost all extant lizard species eat because peoplke have been collecting them for hundreds of years and pickling them in museum jars, and eventually somebody goes in and opens up their stomachs.

  16. #16 Alec T
    February 29, 2008

    Darren, do more of this species identification stuff! It’s very fun.

  17. #17 Andreas Johansson
    February 29, 2008

    Secondary herbivory? Squamata don’t derive from herbivorous ancestors, do they?

  18. #18 Sam Heads
    March 2, 2008

    Hi Darren,

    I was recently nominated for the Excellent Blog Award. As part of the award, I must nominate ten other blogs and Tet Zoo is certainly worthy of excellent blog status!

    All the best,

    Sam

  19. #19 Darren Naish
    March 2, 2008

    Sam, you are a king among palaeoentomologists. I thank you and only hope that I might return the favour :)

  20. #20 David Marjanovi?
    March 2, 2008

    Squamata don’t derive from herbivorous ancestors, do they?

    No.

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