20th International Congress of Arachnology

105

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

International Congress of Arachnology

Department of Biology, San Diego State University,

5500 Campanile Drive, San Diego CA 92182 USA;

Department of Biology, University of California

Riverside, Riverside, CA 92521, USA

mhedin@mail.sdsu.edu

The spider genus

Aliatypus

includes fourteen described

species, twelve of which are restricted to California. Aliaty-

pus are stocky, medium-sized (6–20 mm) subterranean

spiders that cover silk-lined burrows with a wafer-like

trapdoor. These spiders are generally highly dispersal-lim-

ited with strong preferences for cool, moist microhabitats,

and prior genetic studies have revealed geographically

localized population genetic structuring and evidence for

cryptic speciation. This study focuses on

Aliatypus janus

which is phylogenetically allied with members of the

californicus

group. While most

Aliatypus

species occupy

mid-elevation upland habitats and have relatively small

geographic distributions,

A. janus

has an atypically large

geographic distribution–populations occur in California

Coast Range xeric canyons, to upper montane forests

near the crest of the southern Sierra Nevada (>2400 m),

to lower xeric habitats in eastern California and western

Nevada. We reconstructed the phylogeographic history

of the

A. janus

complex (plus close outgroups) using

a mitochondrial COI and nuclear 28S sample of over

170 specimens from 102 geographic locations. Based

on congruent recovery of multiple geographic clades for

these gene regions, we gathered DNA sequences for six

additional nuclear genes for a subsample of specimens,

placing emphasis on paired low versus high elevation

populations from the western slopes of the southern

Sierra Nevada. Using this multigenic nuclear dataset we

conduct multispecies coalescent analyses to explicitly test

alternative riverine versus elevational gradient divergence

hypotheses. Our results support an elevational gradient

hypothesis, which is further supported by ecological niche

modeling. Overall, this research is novel in providing evi-

dence for cryptic, ecologically-mediated divergence in the

southern Sierra Nevada, in a taxonomic group otherwise

dominated by divergence via niche conservatism.

Keywords: molecular systematics, speciation, trapdoor

spiders, elevational zonation

Oral presentation

The good, the bad and the ugly: the asso-

ciation between a bromeliad, an ant and

a spider

Yann Hénaut

, Bruno Corbara

, Régis Céréghino

, Alain

Dejean

El Colegio de la frontera sur, Unidad Chetumal,

Av. Centenario, Chetumal, Quintana Roo. AP 424,

Mexico;

Clermont Université, Université Blaise

Pascal, Laboratoire Microorganismes, Génome et

Environnement, BP 10448, F-63000 Clermont-

Ferrand, France;

Université de Toulouse; UPS, INP,

Laboratoire Écologie Fonctionnelle et Environnement,

118 route de Narbonne, 31062 Toulouse, France

yhenaut@ecosur.mx

Many spider species live on tank bromeliads that host

arthropods and many other organisms. In Quintana Roo,

Mexico, the neotropical spider

I. caudata

(Dipluridae)

frequently installs its web on the tank-bromeliad

Aechmea

bracteata.

This bromeliad also hosts different ant species

and

I. caudata

appears to be associated with not only the

bromeliad but also with the hairy-panther ant,

Neoponera

villosa

that also inhabits the plant. This association appears

to be climate dependent as floods make the bromeliad a

Noah’s Ark for all spiders living in the inundated forest,

while during the dry season the plants are an attractive but

not obligatory host for arachnids. This association between

the funnel web tarantula, bromeliad and ants also has con-

sequences on the architecture of the web. We describe web

size and damage when associated with

A. bracteata

in the

presence of a

N. villosa

colony, when these ants are absent

but other species of ants are present, and when the spider is

not associated with the bromeliad. In association with the

tank-bromeliad and the hairy-panther ant, spiders have

bigger webs with less damage. This particular association

between a spider, a bromeliad and an ant may be explained

by a lower cost in terms of silk production and also due to

the defensive capacities of the hairy-panther ant towards

eventual spider predators. Such multiple associations may

be implicated in the evolution of spider-ant associations.

Keywords: tank bromeliad,

Neoponera villosa

, funnel

web tarantula, climate