Triploidy in parthenogenetic Chinese Helophorus aquila Angus et al., 2014

Triploidy in parthenogenetic Chinese Helophorus aquila Angus et al., 2014 Robert B. Angus1,2, Fenglong Jia1 1Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, Guangdong, China 2Department of Life Sciences (Insects), The Natural History Museum, Cromwell Road, London SW7 5BD, UK Corresponding authors: Robert B. Angus (r[email protected]); Fenglong Jia ([email protected], [email protected]) Academic editor: Ilya Gavrilov-Zimin|Received 20 August 2025|Accepted 16 September 2025|Published 7 October 2025 https://zoobank.org/A40110AD-6BE8-4F01-ACE7-3ED848A6A335 Citation: Angus RB, Jia F (2025) Triploidy in parthenogenetic Chinese Helophorus aquila Angus et al., 2014. Comparative Cytogenetics 19: 167–169. https://doi.org/10.3897/compcytogen.19.169353 Abstract Checking old unphotographed slides of chromosome preparations in the possession of R.B.A. revealed one slide labelled “frater ♀7g 6/6/13 ✓”. The beetle with these data is a female paratype of H. aquila Angus et al., in the general collection of the Natural History Museum, London. One almost complete dividing nucleus was found, with 32 chromosomes, indicating a triploid nucleus with one chromosome lost in the course of preparation of the slide. Keywords China, chromosomes, Helophorus aquila, triploid Introduction Angus et al. (2014) noted that the A. aquila material was originally thought to belong to H. frater d’Orchymont, 1926 and only recognised as a separate species following discovery of males with a distinctive aedeagus. Angus et al. noted that only three male H. aquila were found out of 102 specimens listed as the type series and in the key to species (p.217) described the species as “parthenogenetic to some extent, males absent or very rare”, contrasted with H. frater “clearly bisexual species with males and females present in approximately equal numbers”. CompCytogen 19: 167–169 (2025) doi: 10.3897/compcytogen.19.169353 https://compcytogen.pensoft.net Copyright Robert B. Angus & Fenglong Jia. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. SHORT COMMUNICATION COMPARATIVE Cytogenetics International Journal of Plant & Animal Cytogenetics, Karyosystematics, and Molecular Systematics A peer-reviewed open-access journal Robert B. Angus & Fenglong Jia / Comparative Cytogenetics 19: 167–169 (2025) 168 The discovery of the nucleus reported here shows H. aquila to be a third species, along with H. brevipalpis Bedel, 1881 and H. orientalis Motschulsky, 1860 to include triploid parthenogenetic females (Angus 1992; Angus, Jia 2020). Material and methods The material studied comprises one slide with the label “ frater ♀7g 6/6/13 ✓”, originally prepared in 2013. ♀7 is the specimen number, g is gut and ✓ means R.B.A. thought there was useful material present. The details of preparation are as described by Angus (2025). No C-banding could be attempted as when the slide was cleaned by immersion first in xylene, then in absolute ethanol, the triploid nucleus could no longer be found, although most other material was still present. Loss of a nucleus from the slide is an unavoidable hazard with this procedure. Results The collection site is shown in Fig. 1a. The principal target of collection at this site Boreonectes emmerichi (Falkenström, 1936) (Angus et al. 2015) and a small sieve was used for collecting. The triploid nucleus is shown in Fig. 1b (as found), c (with sections slightly separated for ease of counting). Fig. 1d shows the chromosomes arranged as a karyogram. The existence of triploid sets is very clear. Figure 1. a collection site for the triploid female H. aquila b, c the triploid nucleus b as found c with sections separated for ease of counting d the chromosomes arranged as a karyogram. The missing chromosome is indicated by a bold dot. Scale bar: 5 μm. Conclusion Helophorus aquila is shown to include triploid parthenogenetic females. Acknowledgements We thank Zhen-ning Chen for hosting us in the Qinghai Normal University and for organising our travel and accommodation on the Tibetan Plateau. Triploid Helophorus aquila 169 References Angus RB (1992) A chromosomal investigation of Helophorus brevipalpis Bedel (Coleoptera: Hydrophilidae) with triploid Spanish females a possible source of American parthenogenetic material. The Entomologist 111(1): 56–60. Angus RB, Angus EM, Jia F-l, Zhang Y (2015) Further karyosystematic studies of the Boreonectes griseostriatus (De Geer) group of sibling species (Coleoptera, Dytiscidae)–characterisation of B. emmerichi (Falkenström, 1936) and additional European data. Comparative Cytogenetics 9(1): 133–144. https://doi.org/10.3897/CompCytogen.v9i1.4463 Angus RB, Jia FL, Chen ZN (2014) A review of the Helophorus frater-praenanus group of species, with description of a new species and additional faunal records of Helophorus Fabricius from China and Bhutan. (Coleoptera: Helophoridae). Koleopterologische Rundschau 84: 209–219. Angus RB, Jia F (2020) Triploidy in Chinese parthenogenetic Helophorus orientalis Motschulsky, 1860, further data on parthenogenetic Helophorus brevipalpis Bedel, 1881 and a brief discussion of parthenogenesis in Hydrophiloidea (Coleoptera). Comparative Cytogenetics 14(1): 1–10. https://doi.org/10.3897/CompCytogen.v14i1.47656 ORCID Robert B. Angus https://orcid.org/0000-0002-3860-5617 Fenglong Jia https://orcid.org/0000-0003-2391-5038