Ermentrude the liolaemine

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!).

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].

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.

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

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

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., Núñez, 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. & Núñez, 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.