DNA Barcoding and Taxonomic Challenges in Describing New Putative Species: Examples from Sootywing and Cloudywing Butterflies (Lepidoptera: Hesperiidae)

Edward Pfeiler

doi:10.3390/d10040111

Abstract

DNA barcoding has resulted in the ‘discovery’ of a vast number of new species and subspecies. Assigning formal scientific names to these taxa remains a major challenge. Names sometimes are newly designated. Alternatively, available valid names can be resurrected from synonymy, based on barcode analyses together with classical taxonomic characters. For the most part, however, new putative species revealed by barcoding studies go undescribed. This situation is most often attributed to insufficient taxonomic expertise with the authors conducting the study, together with a critical lack of formally trained taxonomists. However, even with formal training, and additional supportive data from morphological, ecological or life history characters, other factors can arise that impede new species descriptions. In the present paper, several specific taxonomic challenges that have arisen from barcode analyses in two groups of skipper butterflies (Lepidoptera: Hesperiidae), the Sootywings (Pholisora catullus and P. mejicanus) and the Coyote Cloudywing (Achalarus toxeus) are highlighted and discussed. Both P. catullus and A. toxeus show relatively large intraspecific genetic divergences of barcodes (2–3%) which suggests the possibility of previously unrecognized cryptic speciation within each group. Some of the challenges to providing formal names and clarifying taxonomic status of these cryptic taxa could be largely overcome by (1) barcoding type specimens, (2) clarifying imprecise and often vague or suspect type localities, and (3) by conducting in-depth comparative studies on genitalic morphology.

Highlights

Formal taxonomic descriptions of newly discovered cryptic species are critical for understanding the extent of regional biodiversity and for informing management decisions for conservation [1,2,3]. not often the case, assigning a scientific name to a cryptic lineage revealed by DNA barcoding can be straightforward and relatively rapid
P. mejicanus sourced from GenBank and Barcode of Life Data System (BOLD), revealed a single network and four distinct haplotype groups
Two complete barcodes for P. mejicanus from BOLD resolved in haplotype group 4 and were separated from haplotype group 1 by a minimum of six mutational steps

Summary

Introduction

Formal taxonomic descriptions of newly discovered cryptic species are critical for understanding the extent of regional biodiversity and for informing management decisions for conservation [1,2,3]. not often the case, assigning a scientific name to a cryptic lineage revealed by DNA barcoding can be straightforward and relatively rapid. Formal taxonomic descriptions of newly discovered cryptic species are critical for understanding the extent of regional biodiversity and for informing management decisions for conservation [1,2,3]. Taxonomic studies resulting in new species descriptions lag far behind the vast number of cryptic lineages being ‘discovered’ by barcoding. The most obvious reason for this backlog is a shortage of funding and scarcity of formally trained taxonomists to keep up with the workload generated by molecular studies, resulting in what has been called the ‘taxonomic impediment’ [2,7,8]. Even with formal training, additional challenges in describing new species can sometimes arise. These include a lack of designated types and type localities, or a vague

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Conclusion