Linking genetic diversity and morphological disparity: biodiversity assessment of a highly unexplored family of harvestmen (Arachnida : Opiliones : Neopilionidae) in New Zealand

Abstract

In Opiliones, one of the largest orders within the class Arachnida, with more than 6000 described species, sexual dimorphism can be widespread and exaggerated. This great variety of forms of gender-based dimorphism suggests that sexual selection may play an important role in the diversification of some lineages. It also impacts species identification, assignment of females to described species and biodiversity assessments. Here we use DNA-sequence-based species discovery methods (the Poisson Tree Processes model with Bayesian support values, bPTP, and the Generalized Mixed Yule–Coalescent approach, GMYC, accounting for phylogenetic uncertainty) to shed light on the morphological disparity displayed in several species of neopilionid harvestmen from New Zealand. Both species delimitation analyses recovered many clades that coincide with our prior assignment of morphospecies, based solely on males, and allowed us to assign females and juveniles to these species as well as to identify putative new species and to assign some unidentified species to genera. Several genetic species, particularly Forsteropsalis inconstans and Pantopsalis cheliceroides-listeri, showed complex morphological disparity in the size and shape of the male chelicerae, but also in the general size and coloration patterns of the males. The systematic implications of our results and a possible ecological explanation for the exaggerated traits are discussed. Following our findings, the following taxonomic action is taken: Forsteropsalis nigra is considered a junior synonym of F. inconstans (new synonymy).

Geodiversity inclusiveness in biodiversity assessment

“…Infrequent approaches included snorkelling, scuba diving, Winkler bags and soil cores (Fig S1). Metabarcoding and other molecular techniques were the common laboratory-based approaches used to assess biodiversity (Bakker et al, 2019; Fernández et al, 2014; Prié et al, 2020; Serrana et al, 2019) such as DNeasy PowerSoil DNA Isolation Kit (Qiagen) to extract DNA (Bakker et al, 2019), use of mass-PCR amplification of the COI barcode gene (metabarcoding) from arthropods (Yu et al, 2012), use of eDNA metabarcoding from predator species to assess biodiversity and determine dietary composition (Nørgaard et al, 2021), and others (Fig S2).…”

Species limits and phylogeography of Newportia (Scolopendromorpha) and implications for widespread morphospecies

“…This approach is likely to be valuable in other groups of taxonomically-difficult centipedes that rely heavily on characters of the ultimate leg pair but often lack those legs in fixed specimens, such as Cryptops , where the numbers of tibial and tarsal saw teeth are fundamental taxonomic characters. The identification of developmental stages or adults without key taxonomic characters is becoming standard for many groups of animals, including other arthropod groups, such as insects ( Monaghan et al 2009 ; Gattolliat and Monaghan 2010 ) and arachnids ( Fernández et al 2014 ).…”