Phylogeny and classification of the trapdoor spider genus Myrmekiaphila: an integrative approach to evaluating taxonomic hypotheses

Testing mitochondrial marker efficacy for DNA barcoding in spiders: a test case using the dwarf spider genus Oedothorax (Araneae : Linyphiidae : Erigoninae)

The present study focusses on comparatively assessing the efficacy for DNA barcoding of the two most commonly used mitochondrial markers (cox1 and 16S) in a genus of erigonine spiders. In total, 53 specimens representing five species, including four multi-sampled species, were sampled from several European localities. Initial evaluation of species monophyly was performed through parsimony and Bayesian phylogenetic analyses. Efficacy of mitochondrial markers was tested using operational (including distance-, tree-based measures and Barcode Gap) and evolutionary criteria (using the General Mixed Yule-coalescent Model) for species delimitation. We propose that the cox1 marker can potentially overestimate analyses of biodiversity and thus might not be the preferred marker for DNA species identification and delimitation methods in Oedothorax. Instead, our results suggest that the 16S marker appears to be a promising candidate for such endeavour. Evaluating the contribution and suitability of markers to the re-identification of species, measured by their recovery of well established morphological species, is critical for future studies and for reliable results in species identification in spiders.

Taxonomic revision of the Trapdoor spider genus Eucteniza Ausserer (Araneae, Mygalomorphae, Euctenizidae)

The mygalomorph spider genus Eucteniza Ausserer, 1875 comprises 15 nominal species known only from the southwestern United States (Texas) and Mexico (Northern, Central, and the Baja Peninsula). Eucteniza atoyacensis Bond & Opell, 2002 is considered a nomen dubium; E. rex (Chamberlin, 1940) and E. stolida (Gertsch & Mulaik, 1940) are both considered junior synonyms of E. relata (O.P.-Cambridge, 1895). Twelve new species are described: E. caprica, E. coylei, E. diablo, E. cabowabo, E. huasteca, E. zapatista, E. chichimeca, E. ronnewtoni, E. hidalgo, E. golondrina, E. panchovillai and E. rosalia.

Phylogenetic treatment and taxonomic revision of the trapdoor spider genus Aptostichus Simon (Araneae, Mygalomorphae, Euctenizidae)

This systematic study documents the taxonomy, diversity, and distribution of 40 species of the predominately Californian trapdoor spider genus Aptostichus Simon, 1891. Thirty-three of these species are newly described: Aptostichus dantrippi, Aptostichus cabrillo, Aptostichus pennjillettei, Aptostichus asmodaeus, Aptostichus nateevansi, Aptostichus chiricahua, Aptostichus icenoglei, Aptostichus isabella, Aptostichus muiri, Aptostichus barackobamai, Aptostichus sinnombre, Aptostichus hedinorum, Aptostichus aguacaliente, Aptostichus chemehuevi, Aptostichus sarlacc, Aptostichus derhamgiulianii, Aptostichus anzaborrego, Aptostichus serrano, Aptostichus mikeradtkei, Aptostichus edwardabbeyi, Aptostichus killerdana, Aptostichus cahuilla, Aptostichus satleri, Aptostichus elisabethae, Aptostichus fornax, Aptostichus lucerne, Aptostichus fisheri, Aptostichus bonoi, Aptostichus cajalco, Aptostichus sierra, Aptostichus huntington, Aptostichus dorothealangeae, and Aptostichus chavezi. Most of these species are restricted to the California Floristic Province, a known biodiversity hotspot. Of the 40 recognized species, over half are considered to be imperiled or vulnerable and two have likely gone extinct over the past half-century; the conservation status of only 11 species is considered to be secure. Using 73 quantitative and qualitative morphological characters I propose a preliminary phylogeny for the genus that recognizes four major lineages: the Atomarius, Simus, Hesperus, and Sierra species groups. Additionally, the phylogenetic analysis indicates that adaptations favoring the invasion of the arid desert habitats of southern California have evolved multiple times across the group. The existence of both desert and non - desert species in three of the four species groups makes this genus an ideal candidate for the study of the evolutionary ecology of desert arthropods. A set of molecular characters based on the contiguous mitochondrial DNA genes 16S-tRNA valine-12S is used in an independent analysis to assist in placement of specimens into species. The taxonomy section explicitly identifies the concept employed in species delimitation. Niche based distribution models are constructed to predict the ranges of species for which an adequate number of sampling sites were known.

Phylogenetic reconsideration of Myrmekiaphila systematics with a description of the new trapdoor spider species Myrmekiaphila tigris (Araneae, Mygalomorphae, Cyrtaucheniidae, Euctenizinae) from Auburn, Alabama

The trapdoor spider genus Myrmekiaphila currently comprises 11 nominal species. A recent molecular phylogenetic evaluation of the group identified a number of problems with respect to how species and species groups were delineated by Bond and Platnick in their 2007 taxonomic revision of the genus. We report herein the discovery of a new species, Myrmekiaphila tigrissp. n. The phylogenetic position of the species is evaluated using a molecular phylogenetic approach based on a set of mtDNA markers. Our preferred phylogenetic hypothesis supports the recognition of a new species and further highlights the need to more carefully investigate species boundaries within the genus. These results further indicate that palpal bulb morphology is rapidly evolving and has likely been a contributing factor in rendering a number of species paraphyletic with respect to the molecular data.

Species delimitation and phylogeography of Aphonopelma hentzi (Araneae, Mygalomorphae, Theraphosidae): cryptic diversity in North American tarantulas

BACKGROUND

The primary objective of this study is to reconstruct the phylogeny of the hentzi species group and sister species in the North American tarantula genus, Aphonopelma, using a set of mitochondrial DNA markers that include the animal "barcoding gene". An mtDNA genealogy is used to consider questions regarding species boundary delimitation and to evaluate timing of divergence to infer historical biogeographic events that played a role in shaping the present-day diversity and distribution. We aimed to identify potential refugial locations, directionality of range expansion, and test whether A. hentzi post-glacial expansion fit a predicted time frame.

METHODS AND FINDINGS

A Bayesian phylogenetic approach was used to analyze a 2051 base pair (bp) mtDNA data matrix comprising aligned fragments of the gene regions CO1 (1165 bp) and ND1-16S (886 bp). Multiple species delimitation techniques (DNA tree-based methods, a "barcode gap" using percent of pairwise sequence divergence (uncorrected p-distances), and the GMYC method) consistently recognized a number of divergent and genealogically exclusive groups.

CONCLUSIONS

The use of numerous species delimitation methods, in concert, provide an effective approach to dissecting species boundaries in this spider group; as well they seem to provide strong evidence for a number of nominal, previously undiscovered, and cryptic species. Our data also indicate that Pleistocene habitat fragmentation and subsequent range expansion events may have shaped contemporary phylogeographic patterns of Aphonopelma diversity in the southwestern United States, particularly for the A. hentzi species group. These findings indicate that future species delimitation approaches need to be analyzed in context of a number of factors, such as the sampling distribution, loci used, biogeographic history, breadth of morphological variation, ecological factors, and behavioral data, to make truly integrative decisions about what constitutes an evolutionary lineage recognized as a "species".