20th International Congress of Arachnology

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DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
20th International Congress of Arachnology
over 1,000 identifiable solifuge specimens collected. Series
of juvenile specimens collected can offer the potential of
further insight into some species’ life history. As well, diffi-
culty found in identification work of some species speaks to a
potential need of future taxonomic revisions being necessary.
Keywords: solifugae; solifuge; camel spider; biodiversity;
survey; Big Bend National Park; Texas
Oral presentation
The bizarre world of reproduction in
leiobunine harvestmen: the evolution of
mating behavior
Kasey Fowler-Finn
Saint Louis University, 1324 Lacelede Ave, Saint
Louis, MO 63110, USA
Mating behavior and associated traits are very quickly-
evolving aspects of phenotype in animals, and often highly
divergent among closely-related species. I study North
American leiobunine harvestmen, commonly known as
“daddy longlegs” (Opiliones: Sclerosomatidae). This group
exhibits amazingly diverse, often bizarre, and largely
undescribed mating behavior. During mating, males
secure females in face-to-face ‘embraces’ by hooking their
pedipalps behind the sensory legs of the female. I provide
the first detailed descriptions and quantitative compari-
son of these mating interactions across several species of
leiobunine harvestmen. All species studied exhibited
distinct pre-, peri-, and post-copulatory stages of mating
interactions. However, species differed dramatically in how
long each stage and the overall mating interaction lasted,
levels of aggression, duration of copulation, and likeli-
hood of multiple mating and re-mating. Many species also
exhibited species-specific behavior, most notably including:
sensory leg biting, violent shaking, and stroking the female.
Finally, the morphological traits that determine mating
success varied markedly among species. The high diversity
in mating behavior and variation in the traits determining
mating success suggests complex changes in selection have
contributed to diversification of mating behavior.
Keywords: mating behavior, species comparison, Opiliones,
Sclerosomatidae
Oral presentation
Exploring the chemo-textural familiarity
hypothesis for scorpion navigation
Douglas D. Gaffin, Brad P. Brayfield
Department of Biology, University of Oklahoma,
Norman, OK 73019, USA
The navigation by scene familiarity hypothesis provides
broad explanatory power for how bees and ants navigate
from hive to distant food sources and back with brains
the size of a pepper speck. The premise is that the visual
world is decomposed into pixelated matrices of informa-
tion that are stored and readdressed as the insects retrace
learned routes. Innate behaviors in these insects (including
learning walks/flights and path integration) provide the
important goal-directed views to allow the initial retracing
(i.e., the insect must learn the scene while moving toward
the goal since everything looks different while moving
away). Scorpion navigation may use a similar premise,
with the chemical and textural features of the environment
substituting for visual input. The pectines of scorpions
support dense matrices of about 10,000 chemo- and
mechano-sensitive units called peg sensilla, each contain-
ing at least 10 energetically expensive sensory neurons. We
have long wondered why pectines have so many pegs and
associated neurons. We chose desert grassland scorpions
(Paruroctonus utahensis) to test the chemo-textural
familiarity hypothesis because they emerge onto the sand
from their home burrows at night to pursue insect prey
and somehow find their way back to their burrows. We have
preliminary evidence of learning walks and path integra-
tion in these animals. In addition, given the measured
resolution of peg sensilla, sufficient information exists in
sand’s texture to enable scorpions to retrace previously
experienced paths with little to no chance of confusion. We
are developing behavioral and electrophysiological tests
to explore the possibility that these animals are using a
chemo-textural familiarity approach to relocate their home
burrows and that pectinal complexity reflects the informa-
tion content of the animals’ environment.
Keywords: behavior, electrophysiology, homing, sensory