Ultrasonic songs and stridulum anatomy of Asiophlugis crystal predatory katydids (Tettigonioidea: Meconematinae: Phlugidini)

Abstract

The behavioural ecology of ultrasonic-singing katydids is not well understood, and the general bioacoustics, barely known for a few Neotropical Meconematinae, tends to be overlooked for species from Southeast Asia. These include Asiatic species of Phlugidini, commonly known as crystal predatory katydids. One of its genera, Asiophlugis consists of 16 species for which acoustic signals and stridulum anatomy are broadly unknown. These characters can be used to understand species boundaries. Here, we sampled Asiophlugis from five sites in Malay Peninsula and Borneo Island, recorded the acoustic signals of five species plus one subspecies using ultrasound sensitive equipment, and examined their stridulum anatomy. The calling songs of the taxa involved were documented for the first time. We found that the stridulum anatomy (e.g., tooth distributions, tooth length and tooth density) is distinct between species but less so between subspecies. In contrary, songs of different taxa are different based on acoustic parameters (e.g., pulse duration, peak frequency) and descriptive patterns, even between the subspecies. We also did not observe that song signals are more different in sympatry than in allopatry. Whether this can be generalised requires further sampling, highlighting the need for more research on the ultrasonic acoustic communication in Asiatic katydids. ARTICLE HISTORY

Soundscape of urban-tolerant crickets (Orthoptera: Gryllidae, Trigonidiidae) in a tropical Southeast Asia city, Singapore

“…It was clear that the co-occurring urban-tolerant species partition their calls from each other, as predicted, since the partitioning of call properties between closely related sympatric species is crucial for reproductive isolation (Tan et al 2018(Tan et al , 2019. The distinct differences in both the frequency and time domains of the call properties (even within closely related crickets) reduce interspecific acoustic competition (Sueur 2002;Chek et al 2003), especially since these crickets must also compete with anthropogenic noises (e.g., vehicles and construction) in addition to singing hetero-and conspecific males.…”

“…In contrast, other gryllids which are typically forest-edge or grassland species are only sparsely heard (Tan 2017). Moreover, the acoustic community in the urban environment is limited to calls peaking at non-ultrasonic frequencies ranging from 3.5 to 12 kHz ( Figure 6), while the forests harbour more species which calls at ultrasonic frequencies (Tan et al 2019). These suggest that the harsh urban conditions can only permit very limited groups of crickets to exist.…”

“…Research on the orthopterans from Singapore has caught up in the past decade, particularly on species diversity (e.g., Tan 2010Tan , 2012Tan , 2013, new species discovery (e.g., Gorochov and Tan 2012;Tan and Robillard 2014), ecology (e.g., Tan and Tan 2017;Tan et al 2017a) and natural history (e.g., Tan 2011;Tan et al 2017b;Fung et al 2018). As many as 200 species of orthopterans can be found in the forest remnants of Singapore but studies incorporating bioacoustics data are relatively few (but see Gorochov and Tan 2012;Tan and Robillard 2014) and concerted investigation on the orthopteran calls from Singapore is scanty (but see Tan et al 2018Tan et al , 2019. Furthermore, most of these studies were done in the forested and natural environment rather than the highly urbanised parts of Singapore (but see Tan 2010Tan , 2012.…”

Ultrasonic bioacoustics and stridulum morphology reveal cryptic species amongLipotactesbig-eyed katydids (Orthoptera: Tettigoniidae: Lipotactinae) from Borneo

“…Acoustic recording and analysis generally followed that in Tan et al (2019). In the biological stations in Brunei Darussalam and Sandakan, the katydids were kept in insect cages with nylon netting.…”

“…These include whether their songs can be used to differentiate the species by bioacoustic signals because inter-individuals to inter-species variations are rarely examined (partly owing to insufficient specimens). Particularly, knowledge of bioacoustics of katydids from the hyperdiverse Southeast Asia remains remarkedly poor-owing to the sheer number of species, difficulty of identifying them and relative lack of regional expertise-until recently (Tan et al, 2019).…”