No abstract

Discovery of cryptic species using molecular tools has become common in many animal groups but it is rarely accompanied by morphological revision, creating ongoing problems in taxonomy and conservation. In copepods, cryptic species have been discovered in most groups where fast-evolving molecular markers were employed. In this study at Yeelirrie in Western Australia we investigate a subterranean species complex belonging to the harpacticoid genus Schizopera Sars, 1905, using both the barcoding mitochondrial COI gene and landmark-based two-dimensional geometric morphometrics. Integumental organs (sensilla and pores) are used as landmarks for the first time in any crustacean group. Complete congruence between DNA-based species delimitation and relative position of integumental organs in two independent morphological structures suggests the existence of three distinct evolutionary units. We describe two of them as new species, employing a condensed taxonomic format appropriate for cryptic species. We argue that many supposedly cryptic species might not be cryptic if researchers focus on analyzing morphological structures with multivariate tools that explicitly take into account geometry of the phenotype. A perceived supremacy of molecular methods in detecting cryptic species is in our view a consequence of disparity of investment and unexploited recent advancements in morphometrics among taxonomists. Our study shows that morphometric data alone could be used to find diagnostic morphological traits and gives hope to anyone studying small animals with a hard integument or shell, especially opening the door to assessing fossil diversity and rich museum collections. We expect that simultaneous use of molecular tools with geometry-oriented morphometrics may yield faster formal description of species. Decrypted species in this study are a good example for urgency of formal descriptions, as they display short-range endemism in small groundwater calcrete aquifers in a paleochannel, where their conservation may be threatened by proposed mining.

No abstract

A previously unsurveyed calcrete aquifer in the Yilgarn region of Western Australia revealed an unprecedented diversity of copepods, representing 67% of that previously recorded in this whole region. Especially diverse was the genus Schizopera, with up to four morphospecies per bore and a significant size difference between them. Aims of this study were to: (1) survey the extent of this diversity using morphological and molecular tools; (2) derive a molecular phylogeny based on COI; and (3) investigate whether high diversity is a result of an explosive radiation, repeated colonisations, or both, size differentiation is a result of parallel evolution or different phylogeny, and whether Schizopera is a recent invasion in inland waters. More than 300 samples were analysed and the COI fragment successfully amplified by PCR from 43 specimens. Seven species and one subspecies are described as new, and three possible cryptic species were detected. Reconstructed phylogenies reveal that both explosive radiation and multiple colonisations are responsible for this richness, and that Schizopera is probably a recent invasion in these habitats. No evidence for parallel evolution was found, interspecific size differentiation being a result of different phylogeny. Sister species have parapatric distributions and show niche partitioning in the area of overlap.