Mygalomorph Spiders of the California Floristic Prov...

Mygalomorph spiders include the trapdoor spiders & tarantulas (and kin), a distinctive early-diverging group of spiders. These important ground-dwelling predators can be found in essentially all California Floristic Province (CAFP) habitat types, including coastal dune and scrub habitats, chaparral, oak woodlands, and conifer forests. Mygalomorphs possess life history traits remarkable for spiders – most species require 5-6 years to reach reproductive maturity, and some species live for as long as 15-45 years!! Individual mygalomorph species are generally habitat-specialists, are spatially clumped in appropriate microhabitats, and are extraordinarily sedentary.

The known CAFP mygalomorph fauna is one of the richest in the world, and in the US includes the highest familial (6), generic (12), and known species-level diversity (80). Over 90% of these species are endemic to the CAFP, and many of these are microendemic, known from one or a handful of geographic locations. This known taxonomic diversity is a clear underestimate of true diversity. Because mygalomorphs are highly sedentary and exhibit morphological and niche conservatism, cryptic diversification prevails. Past genetic studies on CAFP mygalomorphs have revealed numerous cryptic species, many of which remain undescribed.

Mygalomorphs are long-lived, habitat specialists with poor dispersal abilities and small geographic ranges: theory predicts that such taxa should be “extinction prone”, at the population and/or species level. Sadly, recent work has verified these theoretical predictions, with researchers documenting unprecedented population and species level extinctions in mygalomorphs from southern Australia, in Mediterranean habitats similar to the CAFP. Whether or not such extinctions are occurring in the CAFP remains largely unknown, although we do know that the original habitats of many CAFP type localities are now destroyed.

We have started this iNAT Project to help learn more about the diversity and spatial distribution of mygalomorph spiders from the CAFP. We hope that many others will participate in this important task. less ↑