Resolving the phylogeny of a speciose spider group, the family Linyphiidae (Araneae)

On a desmitracheate “micronetine” Nippononeta alpina (Li & Zhu, 1993), comb. n. (Araneae, Linyphiidae)

“…Two mitochondrial genes, cytochrome c oxidase subunit I (CO1) and 16S rRNA (16S), and two nuclear genes, 18S rRNA (18S), and 28S rRNA (28S) were amplified and sequenced for Macrargus alpinus and added to the dataset of Wang et al (2015) to test its placement in Linyphiidae. Given that the primary analysis resulted in Macrargus alpinus as a sister group to Nippononeta coreana , the four genes data of one additional Nippononeta species was downloaded from GenBank and added to test the monophyly of the genus Nippononeta and its relationship with Macrargus alpinus .…”

“…Given that the primary analysis resulted in Macrargus alpinus as a sister group to Nippononeta coreana , the four genes data of one additional Nippononeta species was downloaded from GenBank and added to test the monophyly of the genus Nippononeta and its relationship with Macrargus alpinus . Based on the dataset of Wang et al (2015), a total of 132 taxa was included in our matrix: 130 linyphiid species including the type species of Macrargus , seven species from four genera as representatives of desmitracheate “micronetines”, and two representative species of Nippononeta . Most outgroup taxa of Wang et al (2015) were removed; only two representatives of Pimoidae, the sister group of Linyphiidae, were included as outgroups to root the tree.…”

“…Such a classification for “erigonines” has long been puzzled by the observations that some “erigonine” species have genitalia of simple type, but possess haplotracheate systems (Hormiga 2000, Miller and Hormiga 2004), while some “micronetine” species have genitalia of complex type, but possess desmitracheate systems (Millidge 1984, Dupérré 2013, Yan et al 2015). Results of phylogenetic analyses based on molecular data recovered the monophyly of the Linyphiidae, in which the taxa of “micronetines” and “erigonines” nest (Arnedo et al 2009, Wang et al 2015); however, all “micronetine” species with a desmitracheate system form a monophyly (addressed as “desmitracheate micronetines” clade hereafter). Ancestral state reconstructions indicate that both tracheal features and genital characters used in subfamily classification are homoplastic.…”

“…However, Macrargus alpinus Li & Zhu, 1993, occurring in China, was found to have a desmitracheate system, different from its congeners. The “desmitracheate micronetines” clade resulting from phylogenetic analyses is distantly related to Macrargus (Wang et al 2015). Some putative synapomorphies for the desmitracheate “micronetine” genus Nippononeta Eskov, 1992 and for the clade Nippononeta + Agyneta proposed by Yan et al (2015) can also be found in Macrargus alpinus , yet none of them is present in other Macrargus species.…”

“…To test the phylogenetic placement of Macrargus alpinus and its relationships with other desmitracheate “micronetines”, we added the newly sequenced DNA sequence data of Macrargus alpinus into the dataset of Wang et al (2015). In the present study, we propose a new generic placement for Macrargus alpinus based on the result of phylogenetic analysis of the new dataset.…”