A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates

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  A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates Abstract Chelicerata is a megadiverse (over 120,000 species) arthropod clade that includes familiar taxa of profound ecological and economic importance, such as scorpions, spiders and mites 1 . Extant chelicerates share a unique anatomical character, the chelicerae—feeding first appendages terminated by a simple pincer-like chela 2 . The fossil record of these primarily predatory animals spans almost 500 million years 3 , suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods 4 , 5 , 6 , megacheirans 4 , 7 , 8 , 9 , habeliids 10 , 11 , 12 , 13  and mollisoniids 14 , 15  have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe  Megachelicerax cousteaui  gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Ut...

Multimodal courtship communication in a wolf spider

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Multimodal courtship communication in a wolf spider

Abstract

Many animals communicate using multiple sensory modes (e.g., vibratory, visual, chemical), and there is current interest in the role of multimodal signals in mate choice. We tested the hypotheses that male Gladicosa bellamyi wolf spiders (Lycosidae) court females using multimodal signals and that these signals were related to male mating success. Using a laser Doppler vibrometer and video camera, we characterized the vibratory and visual courtship signals of male G. bellamyi. Males courted females with a vibratory signal made of three components: pulses of stridulation, abdominal percussion, and a third unknown percussive element (presumed to arise from rapid abdomen tapping), along with two unique visual displays, a foreleg extension/tap and squared leg arch. Female G. bellamyi show no apparent vibratory signals, but possess visual receptivity displays comparable to some other female lycosid species. We found a strong correlation between the vibratory stridulation component and the visual foreleg extension/tapping display of males, suggesting a multimodal signal. Higher rates of courtship signaling, both visual and vibratory, were associated with increased copulatory success. We conclude that male G. bellamyi exhibits multimodal courtship communication, with simultaneous complex vibratory signals and visual displays, and that higher rates of these signals increase the probability of mating in this species.

Lallo, M. M., & Uetz, G. W. Multimodal courtship communication in a wolf spider. Journal of Zoology. https://doi.org/10.1111/jzo.13209