Abstract
We collected Ectobiidae cockroach specimens from 44 locations in the south of the Yangtze valley. We obtained 297 COI sequences specimens and carried out phylogenetic and divergence dating analyses, as well as species delimitation analysis using a General Mixed Yule Coalescent (GMYC) framework. The intraspecific and interspecific sequence divergence in Ectobiidae cockroaches ranged from 0.0 to 7.0% and 4.6 to 30.8%, respectively. GMYC analysis resulted in 53 (confidence interval: 37–65) entities (likelihood ratio = 103.63) including 14 downloaded species. The COI GMYC groups partly corresponded to the ectobiid species and 52 ectobiid species were delimited successfully based on the combination of GMYC result with morphological information. We used the molecular data and 6 cockroach fossil calibrations to obtain a preliminary estimate of the timescale of ectobiid evolution. The major subfamilies in the group were found to have diverged between ~125–110 Ma, and morphospecies pairs were found to have diverged ~10 or more Ma.
Highlights
Cockroach species are often difficult to differentiate, both at the adult and juvenile stages
The COI General Mixed Yule Coalescent (GMYC) groups partly corresponded to the ectobiid species and 52 ectobiid species were delimited successfully based on the combination of GMYC result with morphological information
Most taxonomic keys for cockroaches are based on adult male genitalia, which means that the females of closely related cockroaches cannot be matched with males of the same species, or females may appear to be entirely different species (Wang, Z.Q., personal observation)
Summary
Cockroach species are often difficult to differentiate, both at the adult and juvenile stages. Cockroaches display high developmental stochasticity, which results in great variation in external spination, setation and coloration [4,5], making it difficult to distinguish species on the basis of morphological characters. The male genitalia is of great value in the discrimination of male adult cockroaches; but for some closely related species, it is very challenging (Zheng et al [6], Che, Y.L., personal observation). Most taxonomic keys for cockroaches are based on adult male genitalia, which means that the females of closely related cockroaches cannot be matched with males of the same species, or females may appear to be entirely different species (Wang, Z.Q., personal observation). The difficulty in distinguishing different developmental stages within a species and the nymphs of different species from each other makes it difficult to PLOS ONE | DOI:10.1371/journal.pone.0169006 January 3, 2017
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