On the morphology and evolution of cicadomorphan tymbal organs

Abstract

Cicadas and many of their relatives (Hemiptera: Cicadomorpha) generate vibroacoustic signals using tymbal organs located on their first two abdominal segments.Although tymbals are well-studied in Cicadidae, their systematic distribution in other Cicadomorpha and their possible homologies to the vibroacoustic mechanisms of other Hemiptera have been debated for more than a century. In the present study, we re-examine the morphology of the musculoskeletal system of cicadomorphan vibroacoustic organs, and we document their systematic distribution in 79 species drawn from across the phylogeny of Cicadomorpha. We also compare their morphology to the recently-described snapping organ of planthoppers (Fulgoromorpha). Based on the structure and innervation of the metathoracic and abdominal musculoskeletal system, we find that several key elements of cicadomorphan vibroacoustic organs that have previously been assigned to the first abdominal segment in fact belong to the second. We find that tymbal organs are nearly ubiquitous in Cicadomorpha, and conclude based on their phylogenetic distribution, that they are likely to be synapomorphic.The unusual tymbal-like organs of the Deltocephalinae and Typhlocybinae, represent derived modifications. Finally, we propose a standardised terminology for sternal components of the cicadomorphan vibrational organs, which can be used in future taxonomic descriptions.

Sexual selection and predation drive the repeated evolution of stridulation in Heteroptera and other arthropods

“…Sound production is one of the principal modes of signalling in animals (Hebets & Papaj, 2005; Ladich & Winkler, 2017; Ronald et al ., 2017) and has attracted scientific interest since the time of Aristotle (Weiss, 1929). Arthropods are champions of acoustic signalling, displaying an extraordinary diversity of sound‐producing mechanisms that are used in a variety of behavioural contexts (Cocroft & Rodriguez, 2005; Čokl & Virant‐Doberlet, 2003; Davranoglou et al ., 2020; Song et al ., 2020; Virant‐Doberlet & Čokl, 2004). At least 200,000 arthropod species also communicate with substrate‐borne vibrational signals that are inaudible to humans (Cocroft & Rodriguez, 2005; Hill & Wessel, 2016), in behavioural contexts that overlap with those used by sound‐producing species.…”

Mesozoic evolution of cicadas and their origins of vocalization and root feeding

“…Sound production behaviour of P. xiai gen. nov. sp. nov. may have been comparable to that of modern Cicadidae, in that the movement of the tymbal muscles in the cavity pulled the tymbal membrane back and forth, causing the inward buckling of the ribs that produce the tymbal membrane to create sound 11 – 13 . The abdominal cavity of Pr.…”

“…Extant Cicadidae consists of slightly more than 3000 worldwide species 2 – 7 , while Tettigarctidae is thought to be a relict group containing only one living genus with two species in Australia 1 , 8 – 10 . Members of Cicadidae are well-known for producing some of the loudest sounds among insects through their tymbal mechanisms that consist of intricate organs producing sound through vibration of a ribbed membrane 11 – 13 . By contrast, Tettigarctidae is a clade that lacks production of loud sounds, and instead uses vibrational signals transmitted through the substrate for communication 14 .…”

Moss bugs shed light on the evolution of complex bioacoustic systems

“…Conversely, various groups of the suborder Auchenorrhyncha employ specialised elastic recoil devices to generate complex vibroacoustic signals that would be impossible to achieve with muscle action alone. The most widely used elastic recoil devices in Auchenorrhyncha involve the buckling of drum-like tymbals in cicadas and their relatives (Cicadomorpha) [20,21] and the recently discovered snapping organs in planthoppers (Fulgoromorpha) [22]. Unsurprisingly, the evolutionary origins of complex traits such as hemipteran vibroacoustic elastic recoil mechanisms have remained a matter of debate [21][22][23][24].…”

“…The most widely used elastic recoil devices in Auchenorrhyncha involve the buckling of drum-like tymbals in cicadas and their relatives (Cicadomorpha) [20,21] and the recently discovered snapping organs in planthoppers (Fulgoromorpha) [22]. Unsurprisingly, the evolutionary origins of complex traits such as hemipteran vibroacoustic elastic recoil mechanisms have remained a matter of debate [21][22][23][24]. Their intricate and microscopic morphologies render them challenging to study, their extreme diversity makes homologizing structures between taxa very difficult, their vibroacoustic organs rarely fossilise, and the systematic placement of certain groups has remained inconclusive, thereby hindering our understanding of how hemipteran biomechanics has changed across time.…”