20th International Congress of Arachnology

143

DENVER MUSEUM OF NATURE & SCIENCE

REPORTS

No. 3, July 2, 2016

attachment by fibrillar adhesion system for smooth surface.

Here, we have examined the whole tarsal appendages of

the jumping spider,

Plexippus setipes

with using scanning

electron microscope to reveal the fine structural charac-

teristics of its dry adhesion system. All eight legs have the

scopula with a pair of claw on the tip of feet. Each scopula

is composed of two groups of setae that are capable of dry

adhesion on smooth surface, however the hook structure

of the claw is advanced to move on the rough surface. The

setae distributed on the bottom side of the tarsal segment

are densely covered by numerous setules. The contact area

of each setule has a triangular shape, and cuticular surface

of the contact area is fully expanded with aid of its elon-

gated stalk. In addition, spontaneous self-adhesion between

the numerous setules and the setae was effectively blocked

due to the numerous microscopic hairs since these hairs

were interspersed on the upper side of the setae.

Keywords: nanostructure, dry adhesion, salticid spider,

tarsal appendage, Plexippus setipes

Poster presentation

Nanoscopic structure of the silk spinning

spigots in the cribellate spider

Nurscia

albofasciata

Myung-Jin Moon, Hoon Kim, Kyo-Jin Kim, Jae-Hwi Seo

Department of Biological Sciences, Dankook Univer-

sity, Cheonan 330-714, Korea

moonmj@dankook.ac.kr

The cribellar silk is considered as a quite different sort

of catching silk with dry-adhesive properties. Here, we

describe the functional significance of the cribellar silk

spigots for capture thread production and its peculiar

sieve-like structure in the titanoecid spider

Nurscia

albofasciata

. By our fine structural observation using the

field emission scanning electron microscopy (FESEM),

surface of the cribellum is covered by hundred of tiny

spigots and its microstructure is quite different from those

of the spigots on the spinnerets with respect to size. All of

these spigots are composed of five segments, and are all

approximately the same length (10 µm). These segmented

and flexible structure enable to bent itself and conjoin

together with adjacent other spigots to form congregate

bundles of spigots. Thus, the calamistrum of the spider

draws silk fibrils from its cribellum and helps combine

them with supporting strands to form a cribellar prey

capture thread. Our fine structural observation support

the hypothesis that physical interaction between cribellum

and calamistrum is likely be attributed to electrostatic

charging during the spinning of fibers on the nano-scale.

Keywords: silk, cribellate spider, nanofiber,

Nurscia

albofasciata

Oral presentation

Repeated evolution of color vision under-

lies rapid diversification of salticid male

coloration

Nathan I. Morehouse

, Daniel B. Zurek

, Lisa A. Taylor

Thomas Cronin

Department of Biological Sciences, University of

Pittsburgh; 2Entomology and Nematology Depart-

ment, University of Florida, Gainesville;

Department

of Biological Sciences, University of Maryland,

Baltimore County

nim@pitt.edu

A major goal of evolutionary biology is to understand

the events that lead to rapid diversification of form in

the living world. Sensory systems are likely to play an

important role in the diversification of signals, par-

ticularly when major changes to sensory systems enable

newfound sensory capabilities in specific taxa. We studied

whether major transitions in color sensitivity underlie the

rapid diversification of male courtship coloration in the

Salticidae, or jumping spiders. In many species of jumping

spiders, males perform elaborate courtship dances that

involve visual signaling as well as vibratory songs. Court-

ing males often showcase colored body parts during these

dances. In the majority of jumping spiders, these male

visual signals are limited to a restricted color gamut,

typically blues, greens, blacks, whites and browns. However,

several jumping spider taxa represent notable departures

from this trend, exhibiting an expanded color palette that

includes yellows, oranges, and reds. These jumping spiders

present something of a conundrum, because data collected

from closely related taxa suggest that their visual systems

International Congress of Arachnology