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
Oral presentation
From the proximate to the ultimate:
vertically-integrated research on the evo-
lution of sociality in Anelosimus studiosus
(Araneae: Theridiidae)
Thomas C. Jones, Nathaniel Q. Hancock
Department of Biological Sciences East Tennessee
State University
Anelosimus studiosus is unusual in that it forms both
single-female subsocial colonies and multi-female social
colonies. Because of this variation, and the underly-
ing variation in individual personality, the species has
proven to be an outstanding model for studies on the
proximate underpinnings and ultimate selection for
the evolution of sociality. This talk will review what we
know about the ecology and neurobiology of aggression
and sociality in this species, and present some new data
illustrating vertically-integrated lines of inquiry. Results
from a study exploring how abiotic factors influence the
species’ distribution suggest that both insolation and
wind exposure affect both summer and winter colony
survival. Another study found that exposure to sub-lethal
levels of Cadmium significantly increases individuals’
boldness and metabolic rate, without affecting overall
coordination and activity. This latter study suggests that
through behavioral modulation, Cadmium could move
more quickly into the ecological food web.
Keywords: sociality, ecology, neurobiology, toxicology
Student - Poster presentation
Morphology of Mundochthonius (Pseudo-
scorpiones) in Western Oregon
David S. Johnston1, Susan E. Masta2
1726 SW 11th Ave Apt #104, Portland, OR 9720, USA;
2Department of Biology, P.O. Box 751, Portland State
University, Portland, OR 97207-0751, USA
Three species of the genus Mundochthonius (Pseudoscor-
piones, Chthoniidae) have previously been identified from
western Oregon; however, our work with other chthoniid
taxa suggests this may be an underestimate of the actual
number of species. This study attempts to identify distinct
morphological forms and determine the total number of
species of Mundochthonius present in western Oregon
and nearby areas. Pseudoscorpions were collected from
temperate wet forests in western Oregon, Washington, and
California; 14 morphological features in 28 individuals
were then examined and analyzed. Species were determined
based on key taxonomic features, particularly coxal spine
shape. Morphological features differed in their degree of
variability: chelal dentition, serrula shape, and flagella
shape did not vary, while overall color, male abdomen
shape, eye shape, epistome shape, tergite chaetotaxy, coxal
spine shape, intercoxal tubercle orientation, cheliceral
dentition, chelal hand appearance, right chela length,
and right palpal femur length varied among individuals.
Coxal spine shape varies more than currently documented
in existing species descriptions: spines often vary in teeth
distribution and number and position of incisions between
spines of the same individual. Updated species descriptions
using alternative taxonomic features may be required to
reflect observed morphological diversity.
Keywords: taxonomy, biodiversity, soil invertebrates,
geographic barriers, morphometrics
Oral Presentation
Species diversity of the endemic genus
Annandaliella in Western Ghats, India
Sunil K Jose
Department of Zoology, Deva Matha College,
Kuravilangad, Kerala, India-686633
Annandaliella Hirst, 1909 is a primitive genus endemic
to Western Ghats. The genus is established by Hirst (1909)
to accommodate the new species A. travancorica Hirst,
1909 collected from Trivandrum. Later two more species
are recorded from this genus: A. pectinifera Gravely, 1935
and A. ernakulamensis Jose & Sebastian, 2008. It is very
close to Plesiophrictus Pocock, 1899 but the presence of
cheliceral spines on the prolateral surfaces distinguishes
it from related genera of theraphosids. The genus is pres-
ently known only from two states of India, indicating