20th International Congress of Arachnology

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Comparative Genomics, California Academy of Sci-
ences, San Francisco, USA
Home to impressive and diverse adaptive radiations, the
Hawaiian Archipelago is a biodiversity hotspot of global
importance. In conjunction with its geographic isolation
and well known geology, the island chain is also considered
a natural laboratory for the study of island biogeography.
Although much of the Hawaiian biodiversity is comprised
of arthropods, very little is known about diversification
and assembly of Hawaiian arthropod communities. In a
collaborative project, we currently aim to understand the
processes underlying Hawaiian arthropod community
assembly. The emerging technologies of next generation
sequencing now allow for unprecedented insights into the
contribution of species interactions, abiotic factors and
island geology, in shaping Hawaii’s diversity. We have devel-
oped next generation sequencing based tools for rapid,
cost efficient and large scale analysis of taxonomy,
biogeography and species interactions. Here, we present
results from the application of Illumina sequencing to:
(1) Multi-locus phylogenetic and taxonomic analyses. By
simple amplicon sequencing, we are building a comprehen-
sive barcode reference library for Hawaiian arthropod taxa.
(2) Metabarcoding of mixed arthropod samples. We have
optimized barcoding protocols for qualitative and quantita-
tive analyses of the species composition in communities.
(3) Large scale population genetics. We have reestablished
microsatellites as cost efficient markers for large scale pop-
ulation genetic studies across multiple species. We present
an Illumina sequencing protocol for these markers and a
simple software solution for data analysis.
Keywords: Illumina sequencing, Hawaii, metabarcoding,
community analysis
Oral presentation
The hemolymph pressure pump of
armored spiders (Araneae)
Christian Kropf
Natural History Museum Bern, Department of Inver-
tebrates, Bernastrasse 15, CH-3005 Bern, Switzerland.
Institute of Ecology and Evolution, University of Bern,
Baltzerstrasse 6, CH-3012 Bern, Switzerland
Hemolymph pressure in spiders serves many functions,
e.g., extension of leg joints. The hemolymph pressure
pump is generally considered to be the prosoma that
can be flattened by dorsoventrally running muscles.
In many taxa of Araneomorphae, a peculiar sclero-
tisation of the body is seen, i.e. sclerotised prosomal
pleurae being immovably connected to carapace and
sternum, a sclerotised pedicel, and abdominal scuta.
A functional-morphological analysis of the armored
species Comaroma simoni (Anapidae), Perania nasuta,
and Indicoblemma lannaianum (Tetrablemmidae)
leads to the hypothesis of a hemolymph pressure pump
in the opisthosoma (and not in the prosoma) of these
(and presumably all armored) spiders. Armored spiders
transformed the prosoma into a stiff, inflexible capsule
by connecting carapace and sternum with a largely
sclerotised pleura, show a strongly thickened opistho-
somal cuticle, adaptations in areas of the opisthosoma
where the cuticle has to be membranous for functional
reasons (e.g., mechanosensitive organs), a pressure-
generating specialized muscular “abdominal sac” and
corresponding cuticular muscle attachments, a reduc-
tion of the prosomal musculi laterales, and a reduced
number of extrinsic coxal leg muscles. By transforming
the prosoma into a stiff capsule and by generating hemo-
lymph pressure in the opisthosoma, armored spiders
presumably protect their sensitive pleurae from predators
(e.g., pompilid wasps) and save energy: the leg coxae
move in a stiff frame provided by the hardened pleura,
in this way making the striated and energy-consuming
musculi laterales and a part of the extrinsic coxal
muscles superfluous. Juveniles of armored spiders show
no or only minor sclerotisation of the body and therefore
presumably generate hemolymph pressure “normally”
in the prosoma. This is explained by the need to retain
membranous pleurae as long as the animals have to
molt and it further explains why no armored species
occur in Mesothelae and Mygalomorphae.
Keywords: functional morphology, hemolymph pressure,
armored spiders, muscles
122 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing