Gondwanan Origin of Tarantulas

Great to see that Saoirse Foley’s thesis chapter on the biogeography of tarantulas has been published (here). This work confirms their Gondwanan origins and, interestingly, demonstrates that at least one lineage of likely arboreal tarantulas and a separate lineage of likely fossorial tarantulas rafted on the Indian subcontinent from Africa to Asia.

Collecting in the Atacama Desert

In January, before COVID19 went global, I enjoyed a brief collecting trip with Andrés Taucare-Ríos. Of note, we discovered a Sicarius six-eyed sand spider preying on a gecko — an observation that has now appeared in the Revista de la Sociedad Entomológica Argentina. This observation is significant given the dominant abundance and potential competition between these two predators in Atacama.

Tarantula Phylogenomics

We are pleased to see that Saoirse Foley’s thesis chapter on the phylogeny of tarantulas is now published in Molecular Phylogenetics and Evolution. Our phylogeny recovers a monophyletic group of New World theraphosid subfamilies, including Aviculariinae, Schismatothelinae and Theraphosinae, as well as good support for what previously were questionable subfamilies, such as Poecilotheriinae and Psalmopoeinae.

Thanks to Martin Hüsser for the following interesting commentary:

21st International Congress of Arachnology

Canterbury New Zealand, 10-15 February 2019 — Chen, Foley, and I enjoyed attending the Arachnology Congress this year. Foley presented his research on tarantulas (“Tarantula phylogenomics: A first phylogeny of major theraphosid spider lineages inferred from transcriptome data sheds light on the evolution of urticating setae”) and Chen talked about building leaf retreats in orb weavers (“There’s more than one way to build a leaf retreat: Convergent solutions in orb- and pseudo-orb web spiders”).

Collecting Spiders in Armenia

Just returned from a productive collecting effort in Armenia. When you need lots of specimens of the same species, temperate habitats are often better than tropical habitats. In the tropics we find plenty of specimens, but but it’s hard to find many of the same species without investing considerable effort. At high elevations in Armenia, Aculepeira talishia is abundant and clustered into communal flocks.

The Global Latitudinal Diversity Gradient Pattern in Spiders

Pleased to see that this paper on global patterns of spider biodiversity has been published, reporting that species richness peaks over the Equator rather than the Tropic of Capricorn, as once claimed. We must caution that this result could easily be swayed by regional differences in taxonomic effort, so these patterns should be recalculated periodically. It’s also worth noting that the equatorial pattern only emerges after correcting for the species-area power law, and most prior claims about a southern-hemispheric peak in species richness for various taxa are probably failing to make this correction. Graphs below show without the correction (left) and with the correction (right).

Collecting Trechaleids in Uruguay

I’m returned from a fun time collecting trechaleids with María José Albo at the Instituto de Investigaciones Biológicas Clemente Estable, Uruguay, and two of her most dedicated and enthusiastic students, Mariana Germil and Mauro Martinez. We went to two sites: Río Santa Lucia, where Paratrechalea is found, and ‎Paysandu, where both Paratrechalea and Trechaleoides were recovered. A thoroughly enjoyable trip to a beautiful country with wonderful colleagues.

Testing the Hall Effect device on a Cockroach

Gluing a magnet to the back of a cockroach turned out to be a bigger challenge than expected: the cuticle is slick and moist, the magnet is heavy (so likes to slide off), and all my usual tools are metal and instantly snap to the magnet. In the end, the solution was to first superglue a piece of acetate to the roach, then score the magnet to make it less slick, and finally superglue the magnet to the acetate. Despite the heavy weight of the magnet, and having it somewhat improperly positioned a bit too far towards the posterior, it seems to record the tiny movements produced by cockroach heartbeats, here about 1.3 beats per second.