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Monday, May 4, 2015
 3:00 PM US Eastern Daylight Time
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Tuesday, May 5, 2015
 4:00 AM Japanese Standard Time
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Gradual evolution of bioluminescence in millipedes
Reconstructing the evolutionary history of a recently discovered bioluminescent millipede
suggests that luminous millipedes likely experienced a gradual escalation of bioluminescent
intensity through evolutionary time. The rediscovery of the California millipede Xystocheir
bistipita after 50 years unexpectedly revealed that the species is bioluminescent. Paul Marek
and Wendy Moore demonstrate that X. bistipita is the evolutionary sister of Motyxia, a New
World bioluminescent millipede, and that bioluminescence likely originated in the group’s
common ancestor and incrementally grew in intensity through evolutionary time. Faint light
originated in the most recent common ancestor of Motyxia and gradually brightened through
the evolutionary diversification of the genus. Millipedes with brighter bioluminescence
possessed larger cyanide glands, suggesting that millipede toxicity appears linked to the
intensification of luminescence. The authors suggest that luminescence in Motyxia may have
initially evolved in response to metabolic stress associated with a hot, dry environment at low
elevations and may have been coopted for use as a warning signal by species that occupy
high-elevation habitats with increased predation risk. The authors conclude that luminescent
intensity in Motyxia exhibits evolutionary escalation through species diversification, and
suggest that the discovery of bioluminescence in X. bistipita provides insights into the
evolution of bioluminescence.
Article #15-00014: “Discovery of a glowing millipede in California and the gradual evolution
of bioluminescence in Diplopoda” by Paul Marek and Wendy Moore
MEDIA CONTACT: Paul E. Marek, Virginia Polytechnic Institute and State University,
Blacksburg, VA; tel: 540-231-5653, 520-904-5884; e-mail: <paulemarek@gmail.com>
Images accompanying this article are available.
AFTER THIS ARTICLE PUBLISHES, it will be available at
http://www.pnas.org/cgi/doi/10.1073/pnas.1500014112