Inferring species boundaries using acoustic and morphological data in the ground cricket genus Gymnogryllus (Orthoptera: Grylloidea: Gryllinae)

Abstract

An important function of song production by male crickets is to attract conspecific females. These sound signals can be used to infer species boundaries as they can provide indirect evidence for reproductive isolation. However, many studies of orthopteran diversity in South-east Asia are based mainly on morphology and only occasionally acoustics. As such, there is a lack of information on how acoustic data can be congruent with morphological data when used to delineate species. Crickets of the genus Gymnogryllus (Grylloidea, Gryllidae), are such an example. Gymnogryllus are relatively speciose, but their calling songs have not been studied. We collected specimens and calling songs of five Gymnogryllus species from South-east Asia. The acoustic parameters of the calls, along with male tegminal venation and morphology genitalia, were compared. All data types showed congruency in distinguishing G. sylvestris and G. leucostictus from each other and from the other species. Inferring species boundaries for G. angustus, G. malayanus, and G. unexpectus using acoustics and tegminal morphometry proves to be more challenging. While acoustics, tegminal morphometry, and genital morphology are likely to be useful for inferring species of Gymnogryllus from different species groups, greater coverage of taxa is needed to resolve taxonomy of closely related Gymnogryllus.

Key words:

• genitalia
• morphometry
• systematics
• South-east Asia
• taxonomy
• tegmen

Acknowledgements

The authors thank Tony Robillard for helping to improve drafts of the manuscript. The collection of material in Kuala Belalong Field Studies Centre, Brunei Darussalam was granted by the Institute for Biodiversity and Environmental Research, Universiti Brunei Darussalam (UBD/AVC-RI/1.21.1 [a]). The authors are grateful to the Institute for Biodiversity and Environmental Research, Universiti Brunei Darussalam, for allowing us to work in Kuala Belalong Field Studies Centre, and to the Biodiversity and Research Innovation Centre (BioRIC), Ministry of Primary Resources and Tourism, Brunei Darussalam for the issuance of our export permits (BioRIC/HoB/TAD/51-73 and 51-80). Permission for the collection of material in Singapore was granted by the National Parks Board (NP/RP10-073). Permission for the collection of material in Peninsular Malaysia was granted by the Research Promotion and Co-ordination Committee, Economic Planning Unit, Prime Minister’s Department (UPE: 40/200/19/2923 and UPE: 40/200/19/3103) and supported by the Institute for Biodiversity, Department of Wildlife and National Parks (Perhilitan). The work of MKT was supported by the Lady Yuen Peng McNeice Graduate Fellowship of the National University of Singapore (NUS). The work of MKT, CYHY, and PMJ was supported in part by the Yale-NUS College’s grant R-607-265-084-121 and by Yale-NUS College’s Centre for International and Professional Experience (CIPE). Portions of this study were completed in partial fulfilment of the requirements for the Yale-NUS College Week-7 Learning Across Boundaries (LAB) module, Genomics in the Jungle.