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Katydids produce sound for signaling and communication by stridulation of the tegmina. Unlike crickets, most katydids are known to sing at ultrasonic frequencies. This has drawn interest in the investigation of the biophysics of ultrasonic sound production, detection, evolution, and ecology (including predator-prey interactions) of these katydids. However, most of these studies are based on species from the Neotropics, while little is known about katydid species from the hyperdiverse region of Southeast Asia. To address this, a concerted effort to document, record, and describe the calling songs of Southeast Asian katydids, especially species that call at ultrasonic frequencies, was made. A study spanning two years (2018-2020) in the Malay Peninsula (Singapore and Malaysia), Borneo (Brunei Darussalam and Sabah), and the Philippines revealed previously unknown calls of 24 katydid species from four subfamilies. The calling songs of Southeast Asian katydid species are highly diversified in terms of time and frequency. Call structure can range from isolated syllables (e.g., Holochlora), continuous trills (e.g., Axylus philippinus), to short pulse-trains (e.g., Euanisous teuthroides) and complex echemes (e.g., Conocephalus spp.), with 87.5% of species having ultrasonic peak frequencies and 12.5% being considered extreme ultrasonic callers (peak frequency >40 kHz). The call spectrum ranges from tonal (e.g., spectral entropy is 6.8 in Casigneta sp. 2) to resonant (entropy is 8.8 in Conocephalus cognatus). Of the 24 species whose calls are described here, we imaged and described the soundproducing structures of 18. This study provides a preliminary overview of the acoustic diversity of katydids in Southeast Asia, and the authors hope to inspire further investigation into the bioacoustics of little-known katydids from these areas. Amassing a database of calling songs and soundproducing organ illustrations from different species is important to address taxonomic impediments while advancing our knowledge about the bioacoustics of Southeast Asian katydids. [ABSTRACT FROM AUTHOR]

The Lebinthini crickets are distributed in Southeast Asia, Western Pacific and tropical South America. They represent more than half of the described species in the subfamily Eneopterinae. These crickets are morphologically and behaviorally diverse, varying in body size, wing morphology (ranging from brachypterous to fully winged) and acoustic signals. They also have a distinctive communication system: high‐frequency calling, vibratory signalling, duetting, and lack of phonotaxis in females. To investigate how these traits evolved and diversified, a clear phylogenetic context is needed with taxonomic and biological data for as many species as possible. Since 2010, the numbers of known species and genera in the tribe have grown considerably, but the type genus Lebinthus and the tribe classification lacked a general revision based on phylogenetic inferences. In this paper, we study the systematics of the Lebinthini and present new phylogenetic results confirming the monophyly of Lebinthini and the relationships established by previous studies. The phylogeny allows us to define three monophyletic subtribes within the Lebinthini with clear morphological features and distribution areas: Cardiodactylina subtribe n., Lebinthina subtribe n., and Ligypterina subtribe n. We also redefine Lebinthus and described two new genera related to Lebinthus, Falcerminthusgen.nov., and Fadinthusgen.nov., each characterized by clear‐cut morphological, anatomical, and acoustic features. Using ancestral state reconstructions, we investigate the evolution of the diverse calling songs in Lebinthini. We demonstrate that both trills and monosyllabic calls were acquired multiple times instead of evolving from simple to complex temporal patterns as suggested from previous studies. We also find that temporal traits and the dominant frequency evolve in a very dynamic way, and that the harmonic of the call, i.e., the dominant frequency, seems to undergo diversification in the subtribe Lebinthina. [ABSTRACT FROM AUTHOR]