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A new melanistic variant of the caterpillar hunter Calosoma wilcoxi LeConte, 1848 from Texas, United States of America and a preliminary phylogeny of the genus Calosoma Weber, 1801 (Coleoptera: Carabidae)
Published online by Cambridge University Press: 18 July 2016
Abstract
Two aberrant ground beetle (Coleoptera: Carabidae) specimens from the genus Calosoma Weber, 1801 were collected in Waco, Texas, United States of America, in 2012–2013. The specimens, which are morphologically most similar to Calosoma wilcoxi LeConte, 1848, but are dark blue-black instead of the typical metallic green. We employed DNA barcoding and phylogenetic methods to confirm the identities of the aberrant specimens. Preliminary phylogenetic analyses of cytochrome oxidase subunit 1 (COI) sequences of central Texas and southwestern species place the aberrant specimens with 100% confidence as C. wilcoxi. The new variant of C. wilcoxi presumably occurs at low densities. Frequent collecting from 2011 to 2014 resulted in the discovery of only two of the aberrant coloured individuals among hundreds of typical green specimens. These specimens (to our knowledge) represent the first published record of melanistic Calosoma from North America. While the majority of North American species in the genus are naturally black, two of the most widely distributed and abundant species, C. scrutator (Fabricius, 1775) and C. wilcoxi, are typically green. We sequenced the aberrant form as well as all species co-occurring with the new colour morph at the collection locality and used records from GenBank and the Barcode of Life Data System to generate a preliminary phylogeny of the genus, which suggested that some of the currently established subgenera are likely not monophyletic.
- Type
- Systematics & Morphology
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- © Entomological Society of Canada 2016
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Subject Editor: Derek Sikes
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