Acoustic and vibrational signaling in true katydid Nesoecia nigrispina: three means of sound production in the one species

The males of Mexican katydids Nesoecia nigrispina (Stal) produce calling songs and protest sounds using the same stridulatory apparatus as in most of the other Ensifera at the base of the elytra. It includes pars stridens on the upper elytron and plectrum on the lower. Calling sounds are 2−pulse series, repeated with a frequency of 2−3 per sec. Protest signals in the form of short trills from the same pulse duration males produce with tactile stimulation. The pulse repetition rate is almost three times higher than that of the calling sounds - up to 10 per sec. The frequency spectra of these signals have maxima in the band of 14−15 kHz. However, in addition to the sounds described, both males and females are capable to produce protest signals of the second type with the help of another sound apparatus, namely with the help of the wings. Insects with removed elytra are unable to produce an audible sound. Thus, the sound is produced by the friction of the wings on the elytra, but there are no specialized stridulatory structures on them. In females, in response to tactile stimulation, short clicks are recorded, which they make, apparently, by the mandibles. Vibrational signals at tremulation are emitted by individuals of both sexes during courtship and males, completing the calling signal cycle and after copulation. It is possible that vibrational signals are an additional factor in reproductive isolation in sympatric species, since the calling sound signals in representatives of the genus Nesoecia are similar and exhibit significant variability.

Sound vs. light: wing-based communication in Carboniferous insects

Acoustic communication is well-known in insects since the Mesozoic, but earlier evidence of this behavior is rare. Titanoptera, an ‘orthopteroid’ Permian-Triassic order, is one of the few candidates for Paleozoic intersex calling interactions: some specimens had highly specialized broadened zones on the forewings, which are currently considered—despite inconclusive evidence—as ‘resonators’ of a stridulatory apparatus. Here we argue that the stridulatory apparatus hypothesis is unlikely because the Titanoptera lack a stridulatory file on their bodies, legs or wings. Instead, comparing these broadened zones with similar structures in extant locusts, flies, and fossil damselflies, we find evidence that the Titanoptera used their wings to produce flashes of light and/or crepitated sounds. Moreover, we describe the first Carboniferous (~310 Mya) Titanoptera, which exhibits such specialized zones, thus corresponding to the oldest record of wing communication in insects. Whether these communication systems were used to attract sexual partners and/or escape predators remain to be demonstrated.

An abdominal stridulation organ in Cyphoderris (Prophalangopsidae) and concerning the systematic classification of the Ensifera (Saltatoria)

Ensiferan insects (crickets, katydids, grigs and allies) are well known for rubbing parts of their cuticle together to produce sound: a process called stridulation. In this article Swedish entomologist Kjell Ander describes a novel (at the time) stridulatory apparatus in the great grig, Cyphoderris monstrosa (Prophalangopsidae), a relict ensiferan found in the mountainous regions of western North America. Ander used preserved specimens to predict the sound-producing function of a pair of abdominal file-scraper apparatuses, although he was never able to directly test his proposed mechanism nor did he speculate as to the adaptive significance of the structures. The article concludes with a review of the systematic placement of various higher level taxa within the order Orthoptera, of which Ensifera is one suborder.

Biology, sounds and vibratory signals of hooded katydids (Orthoptera: Tettigoniidae: Phyllophorinae)

The tettigoniid subfamily Phyllophorinae, distributed in Southeast Asia and Australia, is poorly known. Our study of the biology of Giant Katydid Siliquofera grandis (Blanchard, 1853) from a laboratory culture has shown that these insects mate more than once, the females lay a total of up to 400 eggs during their life, and these hatch after 2–2.5 months. The life cycle from egg to death takes longer than one year. In the laboratory, the insects fed mainly on leaves of various Rosaceae, Ficus, and lettuce, and on fruits. It is known that the males of hooded katydids lack the tegminal stridulatory apparatus typical for Tettigoniidae, but are capable of producing protest sounds using their coxosternal sound-producing organs for stridulation. Here, protest stridulation of the males and females and the sound-producing organs used to produce it have been analyzed in Phyllophorina kotoshoensis Shiraki, 1930 and S. grandis. In addition, nymphal protest sounds produced by friction of the metafemur against the edge of the pronotum and adult protest signals produced with the wings are described. In S. grandis, vibratory signals have been described and studied for the first time: territorial, protest, drumming and rhythmic low-amplitude vibrations emitted by adults and nymphs and pre- and postcopulatory vibrations of the males and females. The territorial signals not accompanied with visible movements of the body may be produced by contracting the antagonist muscles of the thorax and possibly of the legs. Using their coxosternal sound-producing organs males of S. grandis produced also an audible courtship song lasting for several seconds. Acoustic signals may thus both regulate intrapopulation relations and serve for interspecific communication (protest signals). The acoustic communication in Phyllophorinae is probably especially important during mating behavior.

Allometric scaling in two bushcricket species (Orthoptera: Tettigoniidae) suggests sexual selection on song-generating structures

In acoustically communicating bushcrickets (Orthoptera: Tettigoniidae), most signal properties are influenced by the dimensions of the stridulatory apparatus, which in turn reflects body size and condition of the signaller. Females can assess male quality based on acoustic signals, suggesting that male stridulatory structures may be under sexual selection. We investigated scaling relationships between stridulatory structures, body size and body mass in males of the bushcricket Poecilimon veluchianus veluchianus, in comparison to the congeneric Poecilimon ampliatus. Stridulatory structures in P. v. veluchianus exhibited strong left–right correlation and coupling with body size and mass, indicating stabilizing selection for functional integration. In addition, sound-generating (the width of stridulatory teeth) and sound-radiating (mirror area on the right tegmen) structures scaled hyperallometrically to tegmen area, suggesting that both are under sexual selection. Finally, interspecies comparison revealed a steeper slope in tegmen area and stridulatory file length in relation to body size in P. ampliatus than in P. v. veluchianus, implying stronger sexual selection in the former, smaller species. Our study emphasizes the significance of a comparative allometric approach in elucidating evolutionary patterns of sound-generating and -radiating structures.

Pseudolebinthus lunipterus sp. nov.: a striking deaf and mute new cricket from Malawi (Orthoptera, Gryllidae, Eneopterinae)

This article presents an intriguing new cricket species of the tribe Xenogryllini discovered in Northern Malawi. This is the first case of mute and deaf species in the subfamily Eneopterinae; it shows no stridulatory apparatus on short male forewings and no tympana on either side of fore tibiae in both sexes. We introduce the new species and its complete mitogenome and assess phylogenetic relationships based on molecular data obtained from next-generation sequencing genome skimming method. Phylogenetic analyses place the new species within the genus Pseudolebinthus in Xenogryllini, as the sister species of Pseudolebinthus gorochovi Robillard. We describe Pseudolebinthus lunipterus sp. nov., provide illustrations of main morphology, male and female genitalia, photographs of living specimens and information about habitat and update the identification key for species of genus Pseudolebinthus. We discuss the differences between the new species and related taxa and the striking loss of acoustic communication in this cricket.

Tainacanthus ferox, a remarkable new genus and species of katydids from the high mountains of Hispaniola (Orthoptera: Tettigoniidae: Pseudophyllinae: Polyancistrini)

The new genus and species of Polyancistrini katydids Tainacanthus ferox gen. nov., sp. nov. is described from specimens collected in the highest mountains of the Dominican Republic, island of Hispaniola. This is the third genus of Polyancistrini known from Hispaniola and the seventh genus of the tribe. Tainacanthus is distinctive due to the unique architecture of its pronotum, which is a large and bulbous shield with an extended metazona that covers and protects the stridulatory apparatus surrounded by a relatively small number of large and sharp spines. Additionally, all legs are armed with larger and more robust spines than those of Polyancistrus Audinet-Serville, 1831, its most likely closest relative. Tainacanthus inhabits the highest mountains of the Dominican Cordillera Central at over 2,400 m above sea level, living among hard-leaf evergreen vegetation interspersed with pine forests. The type locality is included within the Armando Bermúdez National Park, one of the most important protected areas in the Dominican Republic.

The earliest fossil record of true crickets belonging to the Baissogryllidae (Insecta, Orthoptera, Grylloidea)

Baissogryllidae is an extinct family of the insect superfamily Grylloidea, previously known from Late Jurassic – Early Cretaceous time. A new genus and species, Sinagryllus xinjiangensis gen. et sp. nov., is described here based on a well-preserved forewing from the Lower Jurassic Sangonghe Formation of Xinjiang, northwestern China. It can be attributed to Baissogryllidae based on the combination of the following characteristics: a true mirror in the male tegminal stridulatory apparatus; and a distinct widening of the area between CuA2, lateral part of the diagonal vein, and proximal part of the proximal branch of MP+CuA1. This find represents not only the earliest record of Baissogryllidae, but also the first fossil wing of Grylloidea reported from China.

Presence of a stridulatory apparatus in the manca stages of isopods (Crustacea, Isopoda, Oniscidea)

Armadilloofficinalis Duméril, 1816 (Armadillidae) is a widespread terrestrial isopod species in the Mediterranean basin and on the western coasts of the Black Sea. The species is adapted to live in xeric environments and has mainly nocturnal habits. This species is capable of producing stridulations, which is nowadays recognized as a synapomorphy of the genus. In both sexes, these vibrations are produced by a line of scales on the propodus of pereopod 4 and 5. The main goals of this study are: to describe the manca stages of Armadilloofficinalis; to detect the presence of the stridulatory apparatus in the manca stages; to evaluate the differences of such apparatus in the various manca stages. The manca stages (I, II, III) of Armadilloofficinalis are described for the first time showing: i, the shortest duration (known in literature) of the manca stage I (approximately 30 minutes); ii, the presence of a rudimental stridulatory organ that may be of great importance in terms of evolutionary aspects and adaptation to terrestrial life. Notes on the reproductive biology are also reported. Furthermore, some considerations on future perspectives for A.officinalis as a model species in biotremology are also discussed.