The velvet spiders: an atlas of the Eresidae (Arachnida, Araneae)

A Study in Scarlet: Integrative Taxonomy of the Spider Genus Loureedia (Araneae: Eresidae)

The eresid spider genus Loureedia (Miller et al., 2012) was described a decade ago, despite its type species being described in the mid-19th century, which illuminates the difficulties in obtaining specimens. The genus was initially described as monotypic. Ever since, four other species have been assigned to Loureedia, including three newly discovered ones. Primarily due to the extravagant appearance of the males, stories about the discovery of species of Loureedia have been the subject of relatively wide media coverage over the years, leading to numerous new populations and putative undescribed species being documented by naturalists and citizen scientists. These species, although bearing distinct differences in their coloration patterns, typically vary only slightly in the structure of their copulatory organs, the primary traits used in spider systematics. This highlights an important taxonomic problem: while it is easy to diagnose the genus or recognize the species that belong to it, it is challenging to differentiate the species from one another, particularly when using only a single line of evidence. In this paper, we have tackled this issue using an integrative approach, i.e., a combination of molecular markers (the mitochondrial COI) and traditional morphological characters. The effects of different observational angles on the perceived shape of the conductor are discussed. Except for one species, we obtained DNA data of all members of the genus. Based on these data, the first phylogeny for Loureedia is presented, and two North African species, Loureedia maroccana (Gál et al., 2017) and Loureedia jerbae (El-Hennawy, 2005), are revalidated from synonymy. The distribution records of all described species are mapped.

Two new Eresus species (Araneae, Eresidae) from Xinjiang, China

Background

Eresidae C. L. Koch, 1845 contains nine genera and 102 species, of which 24 species belong to Eresus Walckenaer, 1805. Four species of the family are known from China: E.granosus Simon, 1895 (Beijing), E.kollari Rossi, 1846 (Hebei), E.lishizheni Lin, Marusik & Li, 2021 (Xinjiang) and Stegodyphustibialis (O. Pickard-Cambridge, 1869) (Yunnan).

New information

Two new species of Eresus are described from Xinjiang, China: Eresusda Lin & Li sp. n. and E.yukuni Lin & Li sp. n. Photos and morphological descriptions of new species are given.

Phylogeny- and morphology-based recognition of new species in the spider-parasitic genus Gibellula (Hypocreales, Cordycipitaceae) from Thailand

Thailand is known to be a part of what is called the Indo-Burma biodiversity hotspot, hosting a vast array of organisms across its diverse ecosystems. This is reflected by the increasing number of new species described over time, especially fungi. However, a very few fungal species from the specialized spider-parasitic genus Gibellula have ever been reported from this region. A survey of invertebrate-pathogenic fungi in Thailand over several decades has led to the discovery of a number of fungal specimens with affinities to this genus. Integration of morphological traits into multi-locus phylogenetic analysis uncovered four new species: G.cebrennini, G.fusiformispora, G.pigmentosinum, and G.scorpioides. All these appear to be exclusively linked with torrubiella-like sexual morphs with the presence of granulomanus-like asexual morph in G.pigmentosinum and G.cebrennini. A remarkably high host specificity of these new species towards their spider hosts was revealed, and for the first time, evidence is presented for manipulation of host behavior in G.scorpioides.

Phylogenetic analysis suggests that sociality is associated with reduced effectiveness of selection

The evolution of sociality in spiders is associated with female bias, reproductive skew and an inbreeding mating system, factors that cause a reduction in effective population size and increase effects of genetic drift. These factors act to decrease the effectiveness of selection, thereby increasing the fixation probability of deleterious mutations. Comparative studies of closely related species with contrasting social traits and mating systems provide the opportunity to test consequences of low effective population size on the effectiveness of selection empirically. We used phylogenetic analyses of three inbred social spider species and seven outcrossing subsocial species of the genus Stegodyphus, and compared dN/dS ratios and codon usage bias between social Inbreeding and subsocial outcrossing mating systems to assess the effectiveness of selection. The overall results do not differ significantly between the social inbreeding and outcrossing species, but suggest a tendency for lower codon usage bias and higher dN/dS ratios in the social inbreeding species compared with their outcrossing congeners. The differences in dN/dS ratio and codon usage bias between social and subsocial species are modest but consistent with theoretical expectations of reduced effectiveness of selection in species with relatively low effective population size. The modest differences are consistent with relatively recent evolution of social mating systems. Additionally, the short terminal branches and lack of speciation of the social lineages, together with low genetic diversity lend support for the transient state of permanent sociality in spiders.

A new ladybird spider from Hungary (Araneae, Eresidae)

According to the most recent taxonomic literature, three species of the genus Eresus are known in Central Europe, Eresuskollari, Eresussandaliatus and Eresusmoravicus. We recognized a fourth distinctive species from Hungary, which is described as Eresushermanisp. n.Eresushermani has an early spring copulation period, females have a light grey (grizzled) cephalothorax due to a heavy cover of lightly colored setae, and an epigyne with large flat areas posterior to the epigynal pit, while males are distinguished by a broad and blunt terminal tooth of the conductor. An updated and modified comparative table of Řezáč et al. (2008) to include all four Central European Eresus species, and a simple key to the species group’s species are given. Habitus, epigyne, vulva and conductor of Eresuskollari, Eresusmoravicus and Eresussandaliatus are also illustrated. An annotated list of papers illustrating Eresushermani due to misidentifications is presented.

A giant spider from the Jurassic of China reveals greater diversity of the orbicularian stem group

A large female spider, Nephila jurassica, was described from Middle Jurassic strata of north-east China and placed in the modern genus Nephila (family Nephilidae) on the basis of many morphological similarities, but, as with many ancient fossils, the single specimen lacked synapomorphies of the family (Selden et al. 2011). In order to test the placement within the nephilid phylogenetic tree, Kuntner et al. (2013) calibrated the molecular phylogeny using N. jurassica in three different scenarios based on inferred mitochondrial substitution rates. They concluded that N. jurassica fitted better as a stem orbicularian than a nephilid. Now, a giant male spider has been discovered at the same locality that yielded N. jurassica. The two sexes are considered conspecific based on their similar morphological features, size, and provenance. The male cannot be accommodated in Nephilidae because of its pedipalp morphology, so the new genus Mongolarachne and family Mongolarachnidae are erected for the species. Comparison with possibly related families show that Mongolarachnidae is most likely on the orbicularian stem, close to other cribellate orbicularians (e.g., Deinopoidea), which suggests a greater diversity of cribellate orbicularians during the Middle Jurassic.

Harvestmen of the BOS Arthropod Collection of the University of Oviedo (Spain) (Arachnida, Opiliones)

There are significant gaps in accessible knowledge about the distribution and phenology of Iberian harvestmen (Arachnida: Opiliones). Harvestmen accessible datasets in Iberian Peninsula are unknown, an only two other datasets available in GBIF are composed exclusively of harvestmen records. Moreover, only a few harvestmen data from Iberian Peninsula are available in GBIF network (or in any network that allows public retrieval or use these data). This paper describes the data associated with the Opiliones kept in the BOS Arthropod Collection of the University of Oviedo, Spain (hosted in the Department of Biología de Organismos y Sistemas), filling some of those gaps. The specimens were mainly collected from the northern third of the Iberian Peninsula. The earliest specimen deposited in the collection, dating back to the early 20(th) century, belongs to the P. Franganillo Collection. The dataset documents the collection of 16,455 specimens, preserved in 3,772 vials. Approximately 38% of the specimens belong to the family Sclerosomatidae, and 26% to Phalangidae; six other families with fewer specimens are also included. Data quality control was incorporated at several steps of digitisation process to facilitate reuse and improve accuracy. The complete dataset is also provided in Darwin Core Archive format, allowing public retrieval, use and combination with other biological, biodiversity of geographical variables datasets.

Rotational Scanning Electron Micrographs (rSEM): A novel and accessible tool to visualize and communicate complex morphology

An accessible workflow is presented to create interactive, rotational scanning electron micrographs (rSEM). These information-rich animations facilitate the study and communication of complex morphological structures exemplified here by male arthropod genitalia. Methods are outlined for the publication of rSEMs on the web or in journal articles as SWF files. Image components of rSEMs were archived in MorphBank to ensure future data access. rSEM represents a promising new addition to the toolkit of a new generation of digital taxonomy.