Autocrates maqueti in South Korea: current status, evolutionary origin, and conservation

Among the six species of Autocrates, the disjunct distribution of A. maqueti in the mountains of central mainland China and the eastern part of the Korean Peninsula has drawn significant attention. Since it was first described from the Guangxi and Guizhou provinces in 2006, it has also been reported from the northwestern Qinghai Province in 2006. The species A. maqueti, previously reported erroneously from Korea as A. aeneus or A. vitalisi before its description, was suspected to be an exotic species in Korea owing to its distribution ranging from Southeast Asia to the Himalayas. After being re-identified as A. maqueti (Telnov and Lee 2008) based on a specimen collected in the southeast region, it was later discovered by military personnel in 2008 at the North Korean frontier in Goseong and in 2009 along the northeast coast in Yangyang. Eventually, the species was shown to be distributed nationwide along the east coast, although it has never been reported on the west side of Baekdudaegan Mountain Range (Fig. 1A). The discovery of the beetle from Gyeonggi Province presented on the ‘YouTube’ movie-sharing platform was a fake, in fact collected from Goseong, Gangwon Province (see Supporting Information, Fig. S2). Many intentional fake discoveries in South Korea of Callipogon relictus Semenov, 1899 ( Coleoptera: Cerambycidae) (see Supporting Information, Fig. S3), a critically endangered species and a national symbol, have also been reported online. Distribution records provided by citizen science must be verified and validated carefully.

Our divergence time estimation and ancestral range reconstruction suggest an expansive ancient range of A. maqueti towards East Asia, from central mainland China to the Korean Peninsula during the Neogene, ~5–15 Mya (Fig. 3; node 1) after the divergence between A. maqueti and A. oberthueri occurred in mainland China ~17 Mya (Fig. 3; node 1). The divergence between the Korean and Chinese A. maqueti is heralded by, most possibly, a vicariance event that led to the separation of the Korean A. maqueti subpopulation during the middle Pleistocene at ~1.286 Mya with 95% HPD 0.754 –2.966 Mya (Fig. 3; node 2). This vicariance event can be addressed most plausibly by large-scale marine transgression in the Yellow Sea starting in the Pleistocene, which had been dominated by continental environments since the early Palaeogene (Qin et al. 1989, Zhang et al. 2019). Near the estimated divergence time, the Yellow Sea was land except for a Central Palaeolake during 3.5–0.8 Mya (Qin et al. 1989, Liu et al. 2018; Zhang et al. 2019). The Korean Peninsula was connected to mainland China by the Min-Zhe uplift that connected the south of the Korean Peninsula to Shanghai, and Shandong Peninsula was connected to the central Korean Peninsula by the Qianliyan uplift and to Liaodong Peninsula by the Miaodo uplift (Qin et al. 1989, Li et al. 2014, Liu et al. 2018; Zhang et al. 2019). Considering the current distribution of A. maqueti in the Korean Peninsula, being found only on the eastern side of Baekdudaegan Mountain Range, the most reasonable distribution seems to be related to the Min-Zhe uplift (see Figs 1A, 3C). However, the lack of studies on the natural history of Trictenotomidae is a significant hindrance to further understanding of their phylogeographical history. Surveying the presence of A. maqueti in eastern mainland China and obtaining a more definitive understanding of its current distribution is essential to improve our understanding of its phylogeography, given that the distribution of the beetle is inadequately known. Additionally, their natural history, for example, the oviposition sites of adult females and diets of larvae in nature, remaining unknown, having been inferred only from observations from indoor breeding studies (Lin and Hu 2019, Cho et al. 2022). Such studies will provide valuable information about the conditions optimal for the survival of the species and aid in the observations of its natural history in the wild. Integrating biological traits (e.g. preferred habitat, diet, or climate) with palaeoclimatic and palaeogeographical data provides a more comprehensive understanding of the phylogeographical history of the species and supports conservation planning efforts.

In our study, we aimed to identify whether the population in the Korean Peninsula is true A. maqueti, a similar species, or a migrant population. To reinforce the species delimitation, we used the type specimens of A. maqueti . Unfortunately, all PCR attempts on the type specimens were unsuccessful. Nonetheless, we obtained one sequence (AM_CN_3; see Fig. 2; Supporting Information, Table S 1) from a specimen from Mount Leigongshan, which is situated in the same province as the type locality. All four molecular species delimitation results revealed that A. maqueti in the Korean Peninsula and mainland China belong to a single species (Fig. 2A). The results of phylogenetic and haplotype network analyses showed that the individuals collected from the Korean Peninsula formed independent clades and had clear genetic differences from the Chinese populations (Fig. 2A–C). The absence of noticeable morphological differences makes it impossible to assign subspecies status to the Korean A. maqueti . However, its reciprocal monophyly using neutral markers and current geographical separation might warrant its recognition as an evolutionarily significant unit (Conner and Hartl 2004). Although the population is secure, and breeding has been successful in Korea (Cho et al. 2022; personal communication with local insect breeders: see Fig. 1D–F), it appears to be a globally rare species with severely fragmented distribution, which requires well-planned conservation management strategies. Adopting measures used for other giant forest beetles, such as Callipogon relictus in South Korea (Lee et al. 2021) and Cheirotonus jambar Kurosawa, 1984 ( Coleoptera: Scarabaeidae) in Okinawa Island (Aoyagi 2017), could provide a useful reference for these efforts. The ecology and distribution of both species, Callipogon relictus (Kim et al. 1976, Byun et al. 2007, Yi et al. 2018, Lee et al. 2019, 2021, Kang et al. 2021) and Cheirotonus jambar (Kurosawa 1984, Mizunuma 1984, Aoyagi 2017), were researched comprehensively prior to formulating their conservation plans. Likewise, acquiring accurate information on the ecology and distribution of A. maqueti is vital for implementing effective conservation measures. Thankfully, the recent advances in indoor breeding techniques offer a rare chance to study the ecological requirements of A. maqueti in controlled conditions (Cho et al. 2022; H. K. Jang). Furthermore, maintaining populations through indoor breeding would be needed, as for other gigantic endangered beetles (Yi et al. 2017, Bonacci et al. 2020, Watanabe et al. 2021). Prior to formulating a conservation plan for A. maqueti, it is also crucial to obtain a comprehensive understanding of its ecology and distribution.