Megalopsalis (Megalopsalis) Roewer 1923
Creators: name: Taylor, Christopher K.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Opiliones
Neopilionidae
Megalopsalis

description: Megalopsalis (Megalopsalis) Roewer, 1923
Fig. 4c
Type species: Macropsalis serritarsus Sørensen, 1886, by original monotypy (as replacement name for Macropsalis Sørensen 1886).
Other included species (original combinations): Megalopsalis epizephyros Taylor, 2011; Megalopsalis eremiotis Taylor, 2011; Macropsalis hoggi Pocock, 1903a; Megalopsalis leptekes Taylor, 2011; Megalopsalis pilliga Taylor, 2011; Spinicrus stewarti Forster, 1949; Megalopsalis sublucens Taylor, 2013b; Hypomegalopsalis tanisphyros Taylor, 2011; Pantopsalis tasmanica Hogg, 1910; Spinicrus thrypticum Hickman, 1957.
Description: Pedipalp patella uniform in both sexes, either with well-developed, hypersetose mediodistal apophysis or lacking both distinct apophysis and hypersetose area; tarsal claw with ventral tooth-row. Penis (Fig. 4c) with glans short, subtriangular, basally deep but rapidly narrowing distally; bristle groups relatively long; shaft with strong to weak waist behind bristle groups. Spiracle with grate of mid-length to long, basally reticulate spines with multifurcate to palmate endings, sometimes anastomosing, with lace tubercles present in lateral corner. Distitarsi III and IV usually with paired ventral rows of enlarged, brush-like setae (Taylor 2011; reduced in Megalopsalis sublucens, absent in M. leptekes and M. tanisphyros).
Comments: Members of this subgenus remain morphologically diverse. Most species are united by a unique synapomorphy, the presence of a double row of thick, hollow setae with brush-like ends on the tarsi of legs III and IV (Taylor 2011, 2013b). The function of these structures is unknown though glandular and/or sensory functions have been attributed to comparable structures in Laniatores (Rodriguez & Townsend 2015; Townsend & Enzmann 2018; Gainett et al. 2019). However, brush-like setae have not been observed in M. leptekes or M. tanisphyros (Taylor, 2011).
Based on the features of brush-like setae and the presence or absence of a pedipalpal apophysis, Megalopsalis (Megalopsalis) may be divided between three groups: (1) the M. serritarsus species group of Taylor (2013b), with both brush-like setae and a pedipalpal apophysis; (2) the M. leptekes species group of Taylor (2013b), with a pedipalpal apophysis but no brush-like setae; and (3) a group of M. stewarti, M. sublucens, M. tasmanica and M. thryptica (referred to below as the ‘ M. tasmanica group’) with brush-like setae but no pedipalpal apophysis. The M. serritarsus group may also be distinguished by distitarsi III and IV being basally swollen (Taylor 2011), though M. thryptica has distitarsus IV only swollen (Taylor 2013b).
The names Hypomegalopsalis Taylor, 2011 (type species: M. tanisphyros) and Spinicrus Forster, 1949 (type species: M. tasmanica) are potentially available for the M. leptekes and M. tasmanica species groups, respectively, but are retained in synonymy herein. Both groups are essentially distinguished by the absence of key features only. In the phylogenetic analyses presented above, the M. serritarsus group is associated with the M. leptekes group under equal parsimony but with the M. tasmanica group under implied weights analyses. The M. tasmanica group is not recovered as monophyletic under either parameter. It should also be noted that the brush-like tarsal setae are reduced in number and regularity in M. sublucens, presumably in relation to that species’ small body size (Taylor 2013b). This raises the question of whether their apparent absence in the similarly small-bodied M. leptekes group may also be the result of secondary loss. In light of these considerations, further subdivision of the subgenus Megalopsalis should await the input of further data, hopefully including molecular analysis.
description: Published as part of Taylor, Christopher K., 2025, Further discussion of relationships within Australasian Neopilionidae (Opiliones: Phalangioidea), with description of two new species and eight new genera, pp. 52-82 in Zootaxa 5631 (1) on page 65, DOI: 10.11646/zootaxa.5631.1.2, http://zenodo.org/record/15326621