Annuli and setal patterns in the flagellum of female micro-whipscorpions (Arachnida: Schizomida): Hypotheses of homology across an order

Two new species of Bamazomus Harvey, 1992 from southern China (Schizomida, Hubbardiidae)

Two new schizomid species belonging to Bamazomus Harvey, 1992 are described from China: B.shanghang sp. nov. (♂♀) from Fujian Province and B.songi sp. nov. (♂♀) from Guangdong Province. In addition to their descriptions, illustrations and diagnoses, a distribution map is provided. These are first Bamazomus species from the mainland China and the northernmost in continental Asia.

First description of the male genitalia in a short-tailed whipscorpion (Arachnida: Schizomida), description of the female, and comments on pygidial glands and cuticular ultrastructure of Surazomus algodoal Ruiz & Valente, 2017

The male genitalia of Surazomus algodoal Ruiz & Valente, 2017 are described. Since this is the first attempt to describe male genitalia in the schizomids, we propose new terminology to describe the sclerites of the male genital chamber in the order. We believe that the male genitalia may provide a large set of characters for taxonomic research in schizomids, as the female genitalia have proven to do. The setae and other cuticular structures were investigated using light and scanning electron microscopy (SEM). The female of S. algodoal is described for the first time, including the genitalia, and we highlight the sexual dimorphism present in the species. We also present descriptions of: 1) microtrichia, with respect to their presence/length/distribution, 2) cuticular sensilla, glandular openings and other cuticular structures, proposing new terminology, 3) setae of the pedipalpal trochanter and tarsus. Some changes on the terminology of setae of pedipalpal tibia are also given. These advances may be useful for description in other schizomids. The pygidial glands, mostly ignored in modern papers, were assessed and commented upon.

Patterns in schizomid flagellum shape from elliptical Fourier analysis

The arachnid order Schizomida is a relatively understudied group of soil-dwelling predators found on all continents except Antarctica. While efforts to understand their biology are growing, there is still much to know about them. A curious aspect of their morphology is the male flagellum, a sexually dimorphic, tail-like structure which differs in shape across the order and functions in their courtship rituals. The flagellar shape is important for taxonomic classification, yet few efforts have been made to examine shape diversity across the group. Using elliptical Fourier analysis, a type of geometric morphometrics based on shape outline, we quantified shape differences across a combined nearly 550 outlines in the dorsal and lateral views, categorizing them based on genus, family, biogeographic realm, and habitat, with special emphasis on Caribbean and Cuban fauna. We tested for allometric relationships, differences in disparity based on locations and sizes in morphospace among these categories, and for clusters of shapes in morphospace. We found multiple differences in all categories despite apparent overlaps in morphospace, evolutionary allometry, and evidence for discrete clusters in some flagellum shapes. This study can serve as a foundation for further study on the evolution, diversification, and taxonomic utility of the male flagellum.

Integrative systematics untangles the evolutionary history of Stenochrus (Schizomida: Hubbardiidae), a neglected junkyard genus of North American short-tailed whipscorpions

Until recently, the Nearctic short-tailed whipscorpion genus, StenochrusChamberlin, 1922, included 27 species distributed primarily in Mexico, the USA and Central America. Morphological disparity among its species, associated with their adaptation to diverse habitats, raised the question as to whether Stenochrus was monophyletic. The phylogenetic relationships among short-tailed whipscorpions have only recently begun to be explored, and the monophyly of Stenochrus had never been tested. The present contribution provides the first phylogeny of Stenochrus and related genera, based on 61 morphological characters and 2991 aligned DNA nucleotides from two nuclear and two mitochondrial gene markers, for 73 terminal taxa. Separate and simultaneous analyses of the morphological and molecular data sets were conducted with Bayesian Inference, Maximum Likelihood, and parsimony with equal and implied weighting. Terminals represented only by morphological data (‘orphans’) were included in some analyses for evaluation of their phylogenetic positions. As previously defined, Stenochrus sensuReddell & Cokendolpher (1991, 1995) was consistently polyphyletic and comprised eight monophyletic clades, justifying its reclassification into eight genera including Heteroschizomus Rowland, 1973, revalidated from synonymy with Stenochrus by Monjaraz-Ruedas et al. (2019). Rowland & Reddell’s (1980)mexicanus and pecki species groups were consistently paraphyletic. Orphans grouped with the most morphologically similar taxa.

Too hot to handle: Cenozoic aridification drives multiple independent incursions of Schizomida (Hubbardiidae) into hypogean environments

The formation of the Australian arid zone, Australia's largest and youngest major biome, has been recognized as a major driver of rapid evolutionary radiations in terrestrial plants and animals. Here, we investigate the phylogenetic diversity and evolutionary history of subterranean short-tailed whip scorpions (Schizomida: Hubbardiidae), which are a significant faunal component of Western Australian hypogean ecosystems. We sequenced two mitochondrial (12S, COI) and three nuclear DNA markers (18S, 28S, ITS2) from ∼600 specimens, largely from the genera Draculoides and Paradraculoides, including 20 previously named species and an additional 56 newly identified operational taxonomic units (OTUs). Phylogenetic analyses revealed a large and rapid species radiation congruent with Cenozoic aridification of the continent, in addition to the identification of a new genus in Western Australia and the first epigean schizomid from the Pilbara. Here, we also synonymise Paradraculoides with Draculoides (new synonymy), due to paraphyly and a lack of reliable characters to define the two genera. Our results are consistent with multiple colonisations of the subterranean realm from epigean ancestors as their forest habitat fragmented and retracted, with ongoing fragmentation and diversification of lineages underground. These findings illustrate the remarkable diversity and high incidence of short-range endemism of Western Australia's subterranean fauna, which has important implications for identifying and managing short-range endemic subterranean fauna. They also highlight the advantages of including molecular data in subterranean fauna surveys as all specimens can be utilized, regardless of sex and life stage. Additionally, we have provided the first multi-gene phylogenetic framework for Australian schizomids, which will enable researchers and environmental consultants to identify new taxa or align them to existing lineages.

Description of a new species of Surazomus (Arachnida: Schizomida), with comments on homology of male flagellum and mating march anchorage in the genus

Surazomus saturninoae sp. nov. is described from eastern Amazon. The male has a pentagonal flagellum, similar to those of three other species in the genus. These four species are herein gathered as the arboreus-group of Surazomus. We present a brief synopsis of chaetotaxy description in hubbardiines and several homology proposals for the flagellum of the species in the arboreus-group: the posterior lobes may be homologous to the lateral lobes of hubbardiine species with trilobed flagella; the setal brush with 4-5 setae on the posterior lobe may be composed of one Dl2 seta and enlarged lobular microsetae; the single, median posterior coupling pocket may be homologous to the pair of posterior pockets seen in other hubbardiines; the single, median anterior coupling pocket may be homologous to the pair of pockets on the anterior border of the flagellum seen in other hubbardiines. Based on the morphology of these pockets and the chelicerae within Surazomus, we discuss the anchoring mechanism during the mating march.

Total evidence phylogeny of the North American harvestman family Stygnopsidae (Opiliones : Laniatores : Grassatores) reveals hidden diversity

Systematic relationships among Laniatores have received considerable attention during the past few years. Many significant taxonomic changes have been proposed, particularly in the superfamily Gonyleptoidea. As part of this superfamily, the basalmost Stygnopsidae is the least known family. In order to propose the first total evidence phylogeny of the family, we produced four datasets: three molecular markers – partial nuclear 28S, mitochondrial ribosomal 16S, mitochondrial protein-encoding cytochrome c oxidase subunit I; and 72 morphological characters. With these data, we performed three different phylogenetic analyses: (1) Bayesian Inference with molecular data, and (2) Bayesian Inference and (3) Maximum Likelihood using combined data. Our results are congruent: a monophyletic Stygnopsidae subdivided into two major clades: Stygnopsinae and Karosinae, subfam. nov. The following genera are redefined: Stygnopsis, Hoplobunus and Serrobunus stat. rev. The following taxa are described: Iztlina venefica, gen. nov., sp. nov. and Tonalteca, gen. nov. Additionally, the following changes are proposed: Serrobunus queretarius (Šilhavý, 1974), comb. nov., Stygnopsis apoalensis (Goodnight & Goodnight, 1973), comb. nov., Stygnopsis mexicana (Roewer, 1915), comb. nov., Stygnopsis oaxacensis (Goodnight & Goodnight, 1973), comb. nov., and Tonalteca spinooculorum (Goodnight & Goodnight, 1973), comb. nov. We also discuss the status of the genera Isaeus stat. rev. and Mexotroglinus. Finally, we discuss the evolution of male genitalia and convergence of selected homoplastic diagnostic characters.

Rowlandius dumitrescoae species group: new diagnosis, key and description of new cave-dwelling species from Brazil (Schizomida, Hubbardiidae)

The Rowlandiusdumitrescoae species group is reviewed and rediagnosed, and its composition is revised. The group now includes Rowlandiuscousinensis, Rowlandiusdecui, Rowlandiusdumitrescoae, Rowlandiusinsignis, Rowlandiuslinsduarte, Rowlandiusmonensis, Rowlandiuspeckorum, Rowlandiuspotiguar, Rowlandiussul, Rowlandiusubajara, and Rowlandiuspedrosoisp. n. A new species is described from a cave in northeast Brazil (Santa Quitéria, Ceará). Identification keys and distributional maps are provided for the species of the group. Sixteen species of Schizomida, including five of Rowlandius, are currently recognized from Brazil.