Evolution, 56(6), 2002, pp. 1123–1135

CRYPTIC SPECIATION IN THE ANADENOBOLUS EXCISUS MILLIPEDE SPECIES

COMPLEX ON THE ISLAND OF JAMAICA

J. E. BOND1,2 AND P. SIERWALD2,3

1Department of Biology, East Carolina University, Howell Science Complex, N411, Greenville, North Carolina 27858

E-mail: bondja@mail.ecu.edu

2Department of Zoology, Insect Division, Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605

3E-mail: psierwald@fmnh.org

Abstract. Anadenobolus excisus is a large species of millipede endemic to the Caribbean Island of Jamaica. Initial

detailed morphological studies showed little or no discrete variation across this species’ distribution in somatic or,

in particular, genitalic morphology. However, a molecular survey based on ;1000 base pairs of the mitochondrial

(mtDNA) 16S rRNA gene that examines 242 individuals sampled from 54 localities reveals three highly divergent

mtDNA lineages. A lack of discrete morphological differentiation suggests that genetic and morphological divergence

may be decoupled, a pattern inconsistent with a number of evolutionary models. In contrast to minimal morphological

divergence, size variation among mtDNA lineages suggests that character displacement has occurred and that these

lineages are cohesive in sympatry. We conclude that A. excisus is actually a complex of three cryptic species and that

morphological approaches to delineating millipede species may sometimes underestimate evolutionary diversity.

Key words. Character displacement, Diplopoda, mitochondrial DNA, phylogeography, phylogenetic species, Rhinocricidae.