Phylogenetic affinities of Phobetinus to other pirate spider genera (Araneae: Mimetidae) as indicated by spinning field morphology

Temperature fluctuations during embryonic development implicated in a naturally occurring instance of abnormal spinnerets in the spider Australomimetus maculosus (Araneae, Mimetidae)

We record developmental abnormalities of the spinnerets in a field-collected adult male specimen of Australomimetus maculosus. These include (1) a supernumerary right posterior lateral spinneret (PLS), (2) ectopic piriform silk gland spigots and tartipores on the left PLS that are normally restricted to anterior lateral spinnerets (ALSs), and (3) what appear to be ectopic ALS sensilla on the left posterior median spinneret (PMS). Published results of teratological experiments and climate data for the collection site indicate that fluctuating sub- and supra-optimal temperatures during embryogenesis may have been responsible for these anomalies. This specimen thus supports the view that spinneret abnormalities, among other aberrations, may be induced when embryos of entelegyne spiders are exposed to fluctuations between high and low temperatures, whether in the laboratory or, as here, in nature. To our knowledge, the ectopic structures seen on the left PLS and left PMS have not been observed previously. Their locations are consistent with a hypothesis by which only the lateral portion of the araneomorph ALS is serially homologous to the PLS, while the remainder of the ALS, along with the colulus/cribellum, is homologous to the PMS.

Hers and his: Silk glands used in egg sac construction by female spiders potentially repurposed by a 'modern' male spider

Cylindrical silk gland (CY) spigots distinguish a large clade of modern spiders, the CY spigot clade, which includes all entelegyne spiders and their closest relatives. Following a widespread paradigm, CYs and their spigots are only known to occur in female spiders and they produce silk used in the construction of egg sacs. Here we report the occurrence of a CY spigot or CY nubbin on each posterior median spinneret (PMS) in males (5th stadium and later) of the spider Australomimetus maculosus. Late juvenile males had a CY spigot on each PMS, whereas adult males either had a CY spigot or, more often, a non-functional CY nubbin. This indicates that potential CY use by males is at least largely limited to late juvenile instars and is not involved with egg sac construction. Despite the presence of CY spigots in both sexes, sexual dimorphism with respect to CYs was still evident since males lacked the CY spigot on each posterior lateral spinneret present in late juvenile and adult females, and CY spigots of males never had the wide shaft and opening of adult females. This study adds to our knowledge of spinning apparatus variability in modern spiders and demonstrates an exception to the paradigm that, in the CY spigot clade, such spigots are restricted to female spiders.

A morphological and combined phylogenetic analysis of pirate spiders (Araneae, Mimetidae): evolutionary relationships, taxonomy and character evolution

Mimetidae is one of the three families within Araneoidea whose members do not spin foraging webs, but are unique in displaying a complex prey-capture behaviour known as aggressive mimicry. Mimetids are distributed worldwide and are most diverse in the tropics of Central and South America. Here we provide a comprehensive phylogeny of pirate spiders (Mimetidae) based on analyses that combine morphological and multigene nucleotide sequence data. We scored 147 morphological characters for 55 mimetids and 16 outgroup taxa and combined it in a total-evidence approach with the sequence data of Benavides et al. (2017) which included two nuclear ribosomal genes, 18S rRNA and 28S rRNA, two mitochondrial ribosomal genes, 12S rRNA and 16S rRNA, the nuclear protein-encoding gene histone H3 and the mitochondrial protein-encoding gene cytochromec oxidase subunitI. We analysed the combined dataset using parsimony, maximum-likelihood and Bayesian inference methods. Our results support the monophyly of Mimetidae and of the genera Gelanor, Ero, Anansi and Australomimetus. Mimetidae is sister to Arkyidae + Tetragnathidae. Mimetus as currently circumscribed is not monophyletic under any analytical approach used, although several lineages within the genus are consistently found in our analyses. We describe, illustrate and discuss the morphological synapomorphies that support the main clades of Mimetidae. The following nomenclatural changes are proposed: Ermetus koreanus (Paik, 1967), the sole species of the genus, is transferred to Ero C.L. Koch, 1836 and thus Ermetus Ponomarev, 2008 is a junior synonym of Ero C.L. Koch, 1836 (new synonymy) and Ero koreana Paik, 1967 becomes a revalidated combination. Phobetinus sagittifer Simon, 1895, the type species of the genus, is transferred to Mimetus Hentz, 1832 and thus Phobetinus Simon, 1895 is a junior synonym of Mimetus Hentz, 1832 (new synonymy), which results in two changes: Mimetus sagittifer (Simon, 1895), new combination and Mimetus investus (Simon, 1909), new combination. Reo latro Brignoli, 1979, the type species of the genus, is transferred to Mimetus and thus Reo Brignoli, 1979 is a junior synonym of Mimetus (new synonymy), which results in the following two changes: Mimetus latro Brignoli, 1979, new combination and Mimetus eutypus Chamberlin & Ivie, 1935, revalidated combination. Arochoides integrans Mello-Leitão, 1935 is transferred to Tetragnathidae (new family placement). The type specimen of Arochoides integrans, the only species in this genus, is a subadult male of Azilia (Tetragnathidae), most likely Azilia histrio Simon, 1895. Arochoides is a junior synonym of Azilia (new synonymy). http://zoobank.org/urn:lsid:zoobank.org:pub:90F6B3DA-232B-428C-BF38-AEA8953D7685