20th International Congress of Arachnology

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on females. We revise and describe all species of both
genera, including one new species of Jalapyphantes and
five new species of Selenyphantes. Preliminary analyses
of molecular data place Jalapyphantes and Seleny-
phantes as a monophyletic group sister to Pocobletus .
Keywords: taxonomy, Linyphiidae, neotropical, Araneoi-
dea, systematics
Student - poster presentation
Mechanical work of walking on level and
inclined surfaces in the tarantula Eupalaestrus
weijenberghi(Araneae, Theraphosidae)
*Valentina Silva-Pereyra1 , Gabriel C. Fábrica1, Carlo M
Biancardi2, Fernando Pérez-Miles3
1Unidad de Investigación en Biomecánica de la
Locomoción Humana, Facultad de Medicina, Univer-
sidad de la República, Montevideo, Uruguay; 2Polo
de Biomecánica, CENUR Litoral Norte, Universidad
de la República, Paysandú, Uruguay; 3Sección
Entomología, Facultad de Ciencias, Universidad de
la República, Montevideo Uruguay
The metabolic cost of locomotion in cursorial spiders is
directly correlated with the mechanical work done during
each movement cycle. The total mechanical work includes
the energy variations of the body center of mass (bCOM)
regarding the environment (external work) and energy
variations of the body segments in relation to the bCOM
(internal work). Males Eupalaestrus weijenberghi are
characterized by having relatively long legs in relation to
body size. During the sexual period males intensively walk
searching for females, hence locomotion is crucial for
reproductive success. We studied the mechanical work of
locomotion in males, both at level and on gradient (12°).
We registered free displacements of each individual using
four video cameras synchronized and analyzed the bCOM
and body segments movements, after 3-D reconstruction.
At mean speed of 0.025±0.006 ms-1 , the internal work
was lower than expected and did not show significant
differences between level and gradient. It seems that the
number and displacement of legs do not affect the total
mechanical work of this species. The external work,
based on the positive variations of the total mechanical
energy of bCOM, represented in fact the highest fraction
of the total work during locomotion. Great differences
were found in the amplitude of the two total energy
components, kinetic and potential. These differences are
responsible for a low value of pendular energy recovery. In
fact, most of the variations in total energy, and therefore
external work, are due to vertical displacement of bCOM.
On gradient, the external work significantly increased, due
to a larger component of positive gravitational work, and
the energy recovery decreased. The role of the mechanical
paradigms of locomotion in spiders can help to under-
stand the evolution of locomotion in tarantulas, however,
the pendulum mechanism seems not to be highly relevant.
Keywords: Theraphosidae, locomotion, kinematic,
mechanical work, energy recovery
Poster presentation
A new primitive trap door spider in Thailand
Deborah Smith2, Varat Sivayyapram1, Natapot Warrit1
1Center of Excellence in Entomology and Depart-
ment of Biology, Faculty of Science, Chulalongkorn
University, Bangkok 10330, Thailand; 2Department
of Ecology & Evolutionary Biology, University of
Kansas, Lawrence, KS, 66045, USA
The primitive trap door spiders of the genus Liphistius
Schiødte, 1849 (Araneae, Mesothelae) constitute the most
basal group of all extant spiders. These spiders retain
many plesiomorphic characters, such as a segmented
abdomen and spinnerets located on the median area
of the opisthosoma. Liphistius comprises 50 described
species endemic to Myanmar, Laos, Thailand, Malaysia,
and Sumatra; 32 of these species have been described from
Thailand. We found a large, previously unknown Liphistius
population in Mae Wong National Park, Kamphaeng Phet
province at elevations between 1000–1300 m above sea
level. We collected specimens and recorded behavioral
and ecological information, including length and width
of the nest entrances, number of trip lines radiating from
nest entrance, depth of the tunnels, number of openings of
each nest (one or two), nearest neighbor distance among
178 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing