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20 July 2010 DNA barcode data confirm new species and reveal cryptic diversity in Chilean Smicridea (Smicridea) (Trichoptera:Hydropsychidae)
Steffen U. Pauls, Roger J. Blahnik, Xin Zhou, C. Taylor Wardwell, Ralph W. Holzenthal
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Mitochondrial deoxyribonucleic acid (mtDNA) sequence data have been both heralded and scrutinized for their ability or lack thereof to discriminate among species for identification (DNA barcoding) or description (DNA taxonomy). Few studies have systematically examined the ability of mtDNA from the DNA barcode region (658 base pair fragment of the 5′ terminus of the mitochondrial cytochrome c oxidase I gene) to distinguish species based on range-wide sampling of specimens from closely related species. Here we examined the utility of DNA barcode data for delimiting species, associating life stages, and as a potential genetic marker for phylogeographic studies by analyzing a range-wide sample of closely related Chilean representatives of the caddisfly genus Smicridea subgenus Smicridea. Our data revealed the existence of 7 deeply diverged, previously unrecognized lineages and confirmed the existence of 2 new species: Smicridea (S.) patinae, new species and Smicridea (S.) lourditae, new species. Based on our current taxonomic evaluation, we considered the other 5 lineages to be cryptic species. The DNA barcode data proved useful in delimiting species within Chilean Smicridea (Smicridea) and were suitable for life-stage associations. The data also contained sufficient intraspecific variation to make the DNA barcode a candidate locus for widespread application in phylogeographic studies.

South America has high levels of biological diversity and associated high levels of endemism (Malcolm et al. 2006). The continent boasts several hyperdiverse regions (biodiversity hotspots) that contain >1500 endemic species of vascular plants and have lost at least 70% of their primary vegetation (Myers et al. 2000). The central Chilean Winter Rainfall-Valdivian Forests is one of these hotspots (Myers et al. 2000). The high levels of biodiversity and endemism in these forests are a result of their location at a crossroads between the Neotropical and ancient Gondwanan floristic and faunistic regions (Conservation International 2007). In addition, the central Chilean region (from latitude ∼32–48°S) is surrounded by the Pacific Ocean to the west, desert to the north, and very cold and arid regions of Patagonia to the south and east (Cabrera and Willink 1980). Thus, the temperate terrestrial and, particularly, the freshwater faunas of this area have been very isolated since the southern South American landmass began splitting from Australia in the Eocene, between 52 to 35 million years ago (Sanmartín and Ronquist 2004). The high levels of endemism in the aquatic fauna in this region could be the result of persistence of temperate Gondwanan relicts (de Moor and Ivanov 2008) and sustained isolation of this temperate region since the late Eocene.

In the Neotropics, Chile has one of the best known Trichoptera faunas (e.g., Schmid 1964, Flint 1967, 1969, 1974a, 1989, 2002, Holzenthal 2004), which has a high degree of endemism (Flint 1974a, Rojas 2006). At the species level, the Chilean caddisfly fauna is almost 100% endemic (Holzenthal 2004). Our current knowledge of Neotropical Trichoptera clearly indicates that central Chile is a center of diversification for caddisflies. High levels of diversity and endemism in central Chile also are known for other freshwater organisms, including freshwater crabs (Perez-Losada et al. 2009) and fishes (Dyer 2000, Unmack et al. 2009). One reason for the high level of endemism in Chilean caddisflies is that the biogeographic affinity of the Chilean caddisfly fauna lies primarily with Australia, New Zealand, and other biogeographically related regions (e.g., New Caledonia), and not the rest of South America (de Moor and Ivanov 2008). However, this pattern is somewhat different for the Chilean representatives of the genus Smicridea McLachlan 1871. The subgenus Smicridea (Smicridea) currently consists of 113 known species, all occurring in the New World, and most endemic to the Neotropics (Morse 2006). Its closest allies in the family Hydropsychidae are the Neotropical subgenus Smicridea (Rhyacophylax)