Phenotypic plasticity of acoustic traits in high-frequency lebinthine crickets (Orthoptera: Eneopterinae: Lebinthina).

Driven by natural and sexual selection, calling behaviours and call parameters can vary within and between individuals. Phenotypic plasticity can be influenced by environmental conditions (e.g., temperature), size, body condition, and age. Crickets have been classic model organisms for studying the evolution of acoustic communication, but previous studies have focused on field crickets, for which males call at a low frequency, while females exhibit phonotaxis. This study holistically investigated the plasticity of calling behaviours and call parameters across a temperature gradient in a species of lebinthine crickets and examined plasticity between and within individuals. These crickets exhibit a unique communication system, including males calling at a near-ultrasonic frequency while actively searching for females. Ten recording assays at different temperatures were done on males of different sizes and body conditions, half of the assays when the males first became adults and another half 1 month later. Size, body condition, and age group of male crickets, as well as the ambient temperature, had different effects on different calling behaviours (e.g., number of songs produced) and call parameters (e.g., call duration, trill syllable period), even when the acoustic traits were correlated. The crickets also exhibited acclimatisation to the experimental conditions in their calling behaviours and acoustic traits to repeated assays. We also found that calling behaviours were less repeatable than temporal call parameters (e.g., call duration, trill duration), which in turn, were less repeatable than the spectral call parameter (dominant frequency).

Novel system of communication in crickets originated at the same time as bat echolocation and includes male-male multimodal communication.

Understanding the evolutionary origins of communication signals requires careful study of multiple species within a known phylogenetic framework. Most cricket species produce low-frequency calls for mate attraction, whereas they startle to high-frequency sounds similar to bat echolocation. Male crickets in the tribe Lebinthini produce high-frequency calls, to which females reply with vibrational signals. This novel communication system likely evolved by male sensory exploitation of acoustic startle to high-frequency sounds in females. This behavior was previously described for the Lebinthini from Asia. Here we demonstrate that this novel communication system is found in a Neotropical species, Ponca hebardi, and is therefore likely shared by the whole tribe Lebinthini, dating the origin of this behavior to coincide with the origin of echolocation in bats. Furthermore, we document male duets involving both acoustic and vibratory signals not previously described in crickets, and we tentatively interpret it as competitive masking between males.

Biogeographic patterns and diversification dynamics of the genus Cardiodactylus Saussure (Orthoptera, Grylloidea, Eneopterinae) in Southeast Asia.

Southeast Asia harbors an extraordinary species richness and endemism. While only covering 4% of the Earth's landmass, this region includes four of the planet's 34 biodiversity hotspots. Its complex geological history generated a megadiverse and highly endemic biota, attracting a lot of attention, especially in the field of island biogeography. Here we used the cricket genus Cardiodactylus as a model system to study biogeographic patterns in Southeast Asia. We carried out molecular analyses to: (1) infer phylogenetic relationships based on five mitochondrial and four nuclear markers, (2) estimate divergence times and infer biogeographical ancestral areas, (3) depict colonization routes, and summarize emigration and immigration events, as well as in situ diversification, and (4) determine whether shifts in species diversification occurred during the course of Cardiodactylus evolution. Our results support the monophyly of the genus and of one of its species groups. Dating and biogeographical analyses suggest that Cardiodactylus originated in the Southwest Pacific during the Middle Eocene. Our reconstructions indicate that Southeast Asia was independently colonized twice during the Early Miocene (ca. 19-16 Million years ago), and once during the Middle Miocene (ca. 13 Million years ago), with New Guinea acting as a corridor allowing westward dispersal through four different passageways: Sulawesi, the Philippines, Java and the Lesser Sunda Islands. Sulawesi also served as a diversification hub for Cardiodactylus through a combination of high immigration and in situ diversification events, which can be accounted for by the complex geological history of the Wallacea region.

Laying the foundations of evolutionary and systematic studies in crickets (Insecta, Orthoptera): a multilocus phylogenetic analysis.

Orthoptera have been used for decades for numerous evolutionary questions but several of its constituent groups, notably crickets, still suffer from a lack of a robust phylogenetic hypothesis. We propose the first phylogenetic hypothesis for the evolution of crickets sensu lato, based on analysis of 205 species, representing 88% of the subfamilies and 71% tribes currently listed in the database Orthoptera Species File (OSF). We reconstructed parsimony, maximum likelihood and Bayesian phylogenies using fragments of 18S, 28SA, 28SD, H3, 12S, 16S, and cytb (~3600 bp). Our results support the monophyly of the cricket clade, and its subdivision into two clades: mole crickets and ant-loving crickets on the one hand, and all the other crickets on the other (i.e. crickets sensu stricto). Crickets sensu stricto form seven monophyletic clades, which support part of the OSF families, "subfamily groups", or subfamilies: the mole crickets (OSF Gryllotalpidae), the scaly crickets (OSF Mogoplistidae), and the true crickets (OSF Gryllidae) are recovered as monophyletic. Among the 22 sampled subfamilies, only six are monophyletic: Gryllotalpinae, Trigonidiinae, Pteroplistinae, Euscyrtinae, Oecanthinae, and Phaloriinae. Most of the 37 tribes sampled are para- or polyphyletic. We propose the best-supported clades as backbones for future definitions of familial groups, validating some taxonomic hypotheses proposed in the past. These clades fit variously with the morphological characters used today to identify crickets. Our study emphasizes the utility of a classificatory system that accommodates diagnostic characters and monophyletic units of evolution. Moreover, the phylogenetic hypotheses proposed by the present study open new perspectives for further evolutionary research, especially on acoustic communication and biogeography.

A new species of Cardiodactylus (Orthoptera: Grylloidea: Eneopterinae) from Singapore.

Cardiodactylus is a speciose cricket genus belonging to the subfamily Eneopterinae. One new species of Cardiodactylus from Singapore is described: Cardiodactylus admirabilis Tan & Robillard n. sp. Acoustic analysis is also performed on the male calling song. A key to species of Eneopterinae from Singapore is provided.

Levels of Airborne Sound And Substrate-borne Vibration Calling Are Negatively Related Across Neotropical False-leaf Katydids.

Animals often signal in multiple sensory modalities to attract mates, but the level of signaling investment in each modality can differ dramatically between individuals and across species. When functionally overlapping signals are produced in different modalities, their relative use can be influenced by many factors, including differences in signal active space, energetic costs, and predation risk. Characterizing differences in total signal investment across time can shed light on these factors, but requires long focal recordings of signal production. Neotropical pseudophylline katydids produce mate advertisement signals as airborne sound and substrate-borne vibration. Airborne calls, produced via stridulation, are extremely short, high-frequency, and longer-range signals. Conversely, substrate-borne calls produced via abdominal tremulation are longer, low-frequency, relatively more energetically costly, and shorter-range signals. To examine patterns of stridulation and tremulation across species and test hypotheses about the drivers of signal use in each modality, we recorded multimodal signaling activity over 24 hours for males from ten pseudophylline species from a single Panamanian community. We also collected data on demographic and morphological species characteristics, and acoustic features of airborne calls, such as bandwidth, peak frequency, and duration. Finally, we generated a molecular phylogeny for these species and used phylogenetic generalized least squares models to test for relationships between variables while controlling for evolutionary relationships. We found a negative relationship between sound and vibration calling, indicating that substrate-borne vibrational signaling may compensate for reduced airborne signaling in these species. Sound call bandwidth and the proportion of males collected at lights, a proxy for the amount of male movement, also explained a significant amount of variation in sound calling across species, indicating that the overall relationship between the two types of calling signals may be mediated by the specific characteristics of the signals as well as other species traits.

Mechanisms of high-frequency song generation in brachypterous crickets and the role of ghost frequencies.

Sound production in crickets relies on stridulation, the well-understood rubbing together of a pair of specialised wings. As the file of one wing slides over the scraper of the other, a series of rhythmic impacts causes harmonic oscillations, usually resulting in the radiation of pure tones delivered at low frequencies (2-8 kHz). In the short-winged crickets of the Lebinthini tribe, acoustic communication relies on signals with remarkably high frequencies (>8 kHz) and rich harmonic content. Using several species of the subfamily Eneopterinae, we characterised the morphological and mechanical specialisations supporting the production of high frequencies, and demonstrated that higher harmonics are exploited as dominant frequencies. These specialisations affect the structure of the stridulatory file, the motor control of stridulation and the resonance of the sound radiator. We placed these specialisations in a phylogenetic framework and show that they serve to exploit high-frequency vibrational modes pre-existing in the phylogenetic ancestor. In Eneopterinae, the lower frequency components are harmonically related to the dominant peak, suggesting they are relicts of ancestral carrier frequencies. Yet, such ghost frequencies still occur in the wings' free resonances, highlighting the fundamental mechanical constraints of sound radiation. These results support the hypothesis that such high-frequency songs evolved stepwise, by a form of punctuated evolution that could be related to functional constraints, rather than by only the progressive increase of the ancestral fundamental frequency.

Systematics of cryptic species of Lebinthus crickets in Mount Makiling (Grylloidea, Eneopterinae).

In the present study, we address Lebinthus cricket species from Luzon (Philippines) being sympatric in Mount Makiling. We describe Lebinthus puyos new species and redescribe the species Lebinthus sanchezi Bolivar, 1889 and select a neotype series. The species Lebinthus makilingus Otte, 2007 is synonymized under Lebinthus sanchezi. For each species we provide complete descriptions of morphology, including male and female genitalia and forewing venation and we describe calling song for L. sanchezi.

The circadian calling activity of a lebinthine cricket with high-frequency calls is unaffected by cicada choruses in the day.

Background: Many factors can influence circadian rhythms in animals. For acoustically communicating species, both abiotic cues (such as light and temperature) and biotic cues (such as the activity of other animals), can influence the timing of signalling activity. Here we compare the 24-h singing activity of the cricket Lebinthus luae in the laboratory and field to assess whether the presence of other singing insects influences circadian rhythm. Methods: Acoustic monitors were placed in four localities in Singapore and the number of L. luae calls were counted for 10 min of each hour. Individuals from the same localities were captured and recorded in the laboratory in silence but with similar abiotic conditions (temperature and light cycle) as they experience in the field, and the number of calls over 24 h was quantified. Results: The 24-h pattern of L. luae singing was not significantly different between laboratory and field recordings. Singing activity peaked in the morning, with a secondary peak in the afternoon and a smaller peak at night. In the field, L. luae sang in the same locations and at the same time as diurnally singing cicadas, suggesting that the sympatric cicada chorus did not affect the circadian rhythm of communication in this species. Acoustic niche partitioning could potentially explain the ability of this cricket to call alongside cicadas: L. luae sings at higher frequencies than sympatric cicadas, unlike nocturnally singing cricket species that overlap with cicadas in frequency.

Notes on the Eneopterinae (Orthoptera, Grylloidea, Gryllidae) from eastern Sabah.

Based on material collected during recent fieldwork in eastern Sabah, the males of Nisitrus danum Robillard & Tan and Cardiodactylus variegatus Gorochov & Robillard are described for the first time, along with their calling songs. New locality records of N. danum, N. vittatus (Haan), Falcerminthus sandakan (Tan et al.), Cardiodactylus borneoe Robillard & Gorochov and C. variegatus are also presented. New material of Nisitrus species-N. danum and N. vittatus-allowed us to compare these syntopic species.

Description of one new species of the genus Gymnogryllus (Orthoptera, Gryllidae, Gryllinae) from Cameroon with a key for African species.

During a Gryllidae survey in the Southern Cameroonian Plateau, one new species of the genus Gymnogryllus (Orthoptera, Gryllidae, Gryllinae) was discovered and described, namely Gymnogryllus bilongi Um Nyobe & Kekeunou sp. nov. This finding extends the number of species known of this genus in Cameroon at two and proposes a key for African species.

Taxonomy and bioacoustics of little-known Grylloidea crickets (Orthoptera, Ensifera) from Mindanao, Philippines.

Orthopteran surveys were conducted recently on Mindanao Island of the Philippines. Four species new to science are described here: Mistshenkoana lunotan sp. nov., Mistshenkoana higaonon sp. nov. and Ectatoderus dubius sp. nov. from Misamis Oriental; and Phaloria (Phaloria) rotundata sp. nov. from Agusan del Sur. Based on new collected material, Madasumma fuscoirrorata Chopard, 1925, first described based on a single female from Mindanao, is transferred to Varitrella (Cantotrella) fuscoirrorata (Chopard, 1925) comb. nov. We also describe the male of this species for the first time. Madasumma zamboanga Otte, 2007, first described from Zamboanga del Norte (Mindanao), is also transferred to Mnesibulus (Amnesibulus) and redescribed: Mnesibulus (Amnesibulus) zamboanga (Otte, 2007) comb. nov. We also describe previously unknown calling songs of seven species: Falcerminthus parvus (Baroga-Barbecho & Robillard, 2020), Ajorama balatukanis Otte, 1988, Varitrella (Cantotrella) bakeri (Chopard, 1925), Varitrella (Cantotrella) fuscoirrorata (Chopard, 1925) comb. nov., Phaloria (Phaloria) rotundata sp. nov., Ornebius bioculatus Tan et al., 2019 and Ectatoderus dubius sp. nov.

A new species of Indigryllus (Orthoptera, Gryllidae, Eneopterinae, Xenogryllini) from Kerala, India, with first data on acoustics and natural habitat.

In India, the cricket subfamily Eneopterinae is represented by two known genera, Xenogryllus Bolívar, 1890 and Indigryllus Robillard & Jaiswara, 2019. The latter was recently described and is known from a single species I. kudremu Robillard & Jaiswara, 2019 from Karnataka, India. The species was known exclusively from its morphological features and there existed no information on its biology and acoustic features. The present study is a step ahead in understanding the natural history and acoustic signalling in the genus. Based on a collaboration initiated by citizen science observations on the website iNaturalist, we describe a new species, Indigryllus sagani sp. nov. from Kerala, India, with details on its habitat and acoustic signals.

A review of the genus Monseremus Ingrisch, 2018 (Orthoptera, Stenopelmatoidea, Gryllacrididae) from Borneo.

We review the taxonomy of the gryllacridids from a small genus Monseremus Ingrisch, 2018. Monseremus bellus (Tan Wahab, 2018) comb. nov., previously described from Brunei Darussalam before the description of Monseremus, is now added as a second known species in this genus. From a recent field trip, we also added new locality record for the type species Monseremus appendiculatus Ingrisch, 2018. First described from Mount Kinabalu in western Sabah, this species has now been reported also in Mount Silam in eastern Sabah. Males of the type species were also collected for the first time and are described here. Lastly, we provide a dichotomous key to separate these two species.

New taxa and notes on bark and bush crickets (Orthoptera, Grylloidea, Gryllidae, Landrevinae and Podoscirtinae) from Sabah.

From the eastern parts of Sabah, four new species of crickets are described, two of which are from the subfamily Landrevinae and two from the subfamily Podoscirtinae: Duolandrevus (Duolandrevus) nobilis sp. nov. and Odontogryllodes spinifer sp. nov.; and Brevimunda trilineata sp. nov. and Varitrella (Cantotrella) tabin sp. nov., respectively. We also describe the calling songs for three species: Duolandrevus (Bejorama) lambir Gorochov, 2017, Duolandrevus (Duolandrevus) nobilis sp. nov. and Varitrella (Cantotrella) tabin sp. nov. A new locality record (Sabah, Sepilok) for Duolandrevus (Bejorama) lambir Gorochov, 2017, previously known from western Borneo (Sarawak, Lambir Hill and Brunei Darussalam, Kuala Belalong), was also reported.

Taxonomy and bioacoustics of scaly crickets (Orthoptera, Mogoplistidae, Mogoplistinae) from Borneo and Singapore.

A species of scaly cricket is described here: Ornebius lupus sp. nov. from the mangrove forests in Singapore. Ornebius pullus Ingrisch, 2006 is recorded in eastern Sabah for the first time. The calling songs of Cycloptiloides bimaculatus Tan et al., 2021 and Ornebius pullus from Sabah are described. We also revise the diagnosis of Ectatoderus nigrofasciatus Tan et al., 2021 from Brunei Darussalam.

New taxa of the subtribe Lebinthina (Orthoptera: Gryllidae: Eneopterinae: Lebinthini) from New Guinea and nearby islands.

Four new species from three genera of Lebinthina crickets are described here. These include one species of Gnominthus: Gnominthus milneus sp. nov. from Papua New Guinea; two new species of Macrobinthus: Macrobinthus kei sp. nov. and Macrobinthus mamai sp. nov. from Maluka (Indonesia) and Papua New Guinea, respectively; and one species of Microbinthus: Microbinthus elegans sp. nov. from Papua New Guinea.

A review of the genus Changiola (Orthoptera: Grylloidea: Pteroplistinae) and description of the first species from Borneo.

The taxonomy of the little-known cricket genus Changiola from the subfamily Pteroplistinae is reviewed here. This genus consisted of three species, two from Malay Peninsula and one from Indochina. Here, we describe a new species from Borneo, the first from the island: Changiola sarawakensis n. sp. We also provide a key to the species, although it is likely that more species will be added to this genus with more sampling in the region.

New species of Phaloria (Orthoptera: Phalangopsidae: Phaloriinae) from West Papua (Indonesia).

The genus Phaloria belongs to the monophyletic cricket subfamily Phaloriinae. It is s speciose group comprising 68 species found across Southeast Asia and New Guinea and Australia. The numerical diversity of Phaloria in New Guinea is impressive, but more species still await discovery owing to the large size and remoteness of the island. Based on new material collected from Lobo and Kumawa in West Papua (Indonesia), we describe six new species: Phaloria dischidia Tan Robillard, sp. nov. from Lobo; Phaloria paradischidia Tan Robillard, sp. nov. from Kumawa; Phaloria tukul Tan Robillard, sp. nov. from Lobo; Phaloria brevis Tan Robillard, sp. nov. from Kumawa; Phaloria berbeda Tan Robillard, sp. nov. from Lobo; Phaloria lobulata Tan Robillard, sp. nov. from Kumawa. We also record new localities for a species widespread in Lobo and Kumawa: Phaloria nr. aspersa Gorochov, 1996.

A new species of Heminicsara (Orthoptera: Tettigoniidae: Agraeciini) from West Papua (New Guinea).

Heminicsara Karny, 1912 is a katydid genus of Agraeciini from the Axylus genus group. It currently comprises 62 species from mainly New Guinea and surrounding archipelagos. Based on recent fieldwork in Lobo in West Papua, Indonesia, a new species of Heminicsara is described here: Heminicsara incrassata sp. nov. It is most readily characterised from congeners and other species of the Axylus genus group by the male tenth abdominal tergite forming a large shield-shaped plate. This represents the first species of Heminicsara described and known from the south-west of New Guinea.