A multilocus phylogeny of Podoctidae (Arachnida, Opiliones, Laniatores) and parametric shape analysis reveal the disutility of subfamilial nomenclature in armored harvestman systematics

Abstract

The taxonomy and systematics of the armored harvestmen (suborder Laniatores) are based on various sets of morphological characters pertaining to shape, armature, pedipalpal setation, and the number of articles of the walking leg tarsi. Few studies have tested the validity of these historical character systems in a comprehensive way, with reference to an independent data class, i.e., molecular sequence data. We examined as a test case the systematics of Podoctidae, a family distributed throughout the Indo-Pacific. We tested the validity of the three subfamilies of Podoctidae using a five-locus phylogeny, and examined the evolution of dorsal shape as a proxy for taxonomic utility, using parametric shape analysis. Here we show that two of the three subfamilies, Ibaloniinae and Podoctinae, are non-monophyletic, with the third subfamily, Erecananinae, recovered as non-monophyletic in a subset of analyses. Various genera were also recovered as non-monophyletic. As first steps toward revision of Podoctidae, the subfamilies Erecananinae Roewer, 1912 and Ibaloniinae Roewer, 1912 are synonymized with Podoctinae Roewer, 1912 new synonymies, thereby abolishing unsubstantiated subfamilial divisions within Podoctidae. We once again synonymize the genus Paralomanius Goodnight & Goodnight, 1948 with Lomanius Roewer, 1923 revalidated. We additionally show that eggs carried on the legs of male Podoctidae are not conspecific to the males, falsifying the hypothesis of paternal care in this group.

The Opiliones Tree of Life: shedding light on harvestmen relationships through transcriptomics

“…The phylogeny of Laniatores has received recent attention at many levels (Giribet et al, 2010; Sharma and Giribet, 2011; Cruz-López et al, 2016; Sharma et al, 2016). In an unpublished thesis, Kury (1993) divided Laniatores into Insidiatores (Fig 2a–b) and Grassatores (Fig 2c–l), a division found here, but not in some studies that included a meaningful sampling of Laniatores (Giribet et al, 2010; Sharma and Giribet, 2011).…”

“…Resolution within Grassatores has remained elusive except for the recognition of a main division between Phalangodidae and the remaining Grassatores and of the superfamilies Gonyleptoidea, Assamioidea, Zalmoxoidea and Samooidea, and perhaps a clade of Southeast Asian families, Epedanoidea (Sharma and Giribet, 2011), although some of these clades were not supported in re-analyses of the Sharma & Giribet dataset (Cruz-López et al, 2016; Sharma et al, 2016). Here we find Phalangodidae (represented by Sitalcina lobata ) to be the sister group of the remaining Grassatores, a result supported in all analyses conducted to date.…”

“…Epedanoidea is monophyletic in all analyses (although sometimes without significant support), except for the PhyloBayes analysis of matrix VI (Fig. 4), and it is resolved with Epedanidae being sister group to a clade of Petrobunidae and Podoctidae (Fig 2d), although support for these relationships is not optimal (Fig 4; see also Sharma et al, 2016), as it may require additional taxa, including the missing family Tithaeidae and additional species. Epedanoidea has however been difficult to recover in a recent analysis focusing on Podoctidae (Sharma et al, 2016).…”

A new species of Tithaeidae (Arachnida: Opiliones: Laniatores) from Mindanao reveals contemporaneous colonisation of the Philippines by Sunda Shelf opiliofauna

“…The application of molecular phylogenetics to many of these understudied families in Southeast Asia is beginning to shed light on the complexity of harvestman origins in this biogeographic theatre. The harvestman lineages that have given rise to Philippine endemics mostly originated in continental Southeast Asia, with particularly strong biogeographic links to the Sunda Shelf Giribet 2007, 2010;Clouse et al 2011;Sharma andGiribet 2009c, 2011;Sharma et al 2017). This is especially the case for lineages endemic to the islands of Palawan and Mindanao, which have been transiently connected to Borneo and/or the Indo-Chinese Plate during the Cenozoic (Clouse et al 2011;.…”

“…Families with endemics in this archipelago include Epedanidae (particularly the subfamily Dibuninae), Podoctidae (several distantly related genera, corresponding to three erstwhile subfamilies; Sharma et al 2017), Sandokanidae (including the Philippine endemic genus Biantoncopus, as well as many species of Gnomulus) and Petrobunidae (whose type genus, Petrobunus, is endemic to the Philippine islands of Palawan and Panay). These four families are clearly of south-eastern Asian origin, as inferred from distributions and molecular phylogenies (Sharma and Giribet 2009b;Sharma and Giribet 2011;Sharma et al 2017). Another Laniatores family with Philippine endemics is the vagile family Zalmoxidae, which has been described from Luzon, Panay, Mindoro, Mindanao and Palawan (Sharma et al 2011b.…”