A novel genus and cryptic species harboured within the monotypic freshwater crayfish genus Tenuibranchiurus Riek, 1951 (Decapoda: Parastacidae).

Kathryn L Dawkins,Jane M Hughes,Clyde H Wild,James M Furse

doi:10.7717/peerj.3310

Abstract

Identifying species groups is an important yet difficult task, with there being no single accepted definition as to what constitutes a species, nor a set of criteria by which they should be delineated. Employing the General Lineage Concept somewhat circumvents these issues, as this concept allows multiple concordant lines of evidence to be used as support for species delimitation, where a species is defined as any independently evolving lineage. Genetically diverse groups have previously been identified within the monotypic parastacid genus Tenuibranchiurus Riek, 1951, but no further investigation of this diversity has previously been undertaken. Analysis of two mitochondrial DNA gene regions has previously identified two highly divergent groups within this taxon, representing populations from Queensland (Qld) and New South Wales (NSW), respectively. Additional testing within this study of both mitochondrial and nuclear DNA through species discovery analyses identified genetically diverse groups within these regions, which were further supported by lineage validation methods. The degree of genetic differentiation between Qld and NSW populations supports the recognition of two genera; with Qld retaining the original genus name Tenuibranchiurus, and NSW designated as Gen. nov. until a formal description is completed. Concordance between the species discovery and lineage validation methods supports the presence of six species within Tenuibranchiurus and two within Gen. nov. The recognition of additional species removes the monotypy of the genus, and the methods used can improve species identification within groups of organisms with taxonomic problems and cryptic diversity.

Highlights

Species are the fundamental unit of biodiversity, yet there has always been disagreement about criteria by which they should be recognised and the methods by which they shouldHow to cite this article Dawkins et al (2017), A novel genus and cryptic species harboured within the monotypic freshwater crayfish genus Tenuibranchiurus Riek, 1951 (Decapoda: Parastacidae)
Employing the General Lineage Concept (GLC; De Queiroz, 1998), where a species is defined as a metapopulation lineage evolving separately from other lineages, somewhat unites the various species concepts by allowing any evidence of lineage separation to be used as evidence for species delimitation (De Queiroz, 2007)
The genetic distances calculated between the Qld and New South Wales (NSW) groups using COI and 16S were 16.0% and 12.7%, respectively (Table 3)

Summary

Introduction

Species are the fundamental unit of biodiversity, yet there has always been disagreement about criteria by which they should be recognised and the methods by which they shouldHow to cite this article Dawkins et al (2017), A novel genus and cryptic species harboured within the monotypic freshwater crayfish genus Tenuibranchiurus Riek, 1951 (Decapoda: Parastacidae). Employing the General Lineage Concept (GLC; De Queiroz, 1998), where a species is defined as a metapopulation lineage evolving separately from other lineages, somewhat unites the various species concepts by allowing any evidence of lineage separation (and any property emphasised by the alternative concepts) to be used as evidence for species delimitation (De Queiroz, 2007) Does this concept allow multiple lines of evidence to be used, but it allows the evolutionary processes that have caused divergence between lineages to be examined. With the use of molecular techniques comes the potential for signatures of population-level and species-level histories to become confounded, (Edwards, 2008) This can occur when gene trees constructed from a single locus differ from the true genealogical history of a species (Hey & Machado, 2003; Sunnucks, 2000), this problem can potentially be overcome by estimating gene trees from multiple unlinked loci. Mitochondrial alleles accumulate nucleotide substitutions several times faster than nuclear genes due to their lower effective population size, thereby completing the coalescent process much faster and becoming diagnostic of taxa more rapidly (Sunnucks, 2000)

Methods

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Discussion

Conclusion