The first record of the genus Belenois (Lepidoptera: Pieridae) from China

Abstract Background The family Pieridae is a large group of butterflies which plays an important role in evolutionary biology and contains many potential pests (Courtney 1986). Pieridae is a cosmopolitan family while the tropics harbour higher species richness. In a very recent expedition to the Chinese-Indian border area in Tibet Autonomous Region, a migratory species, Belenois aurota (Fabricius, 1793), was discovered for the first time, which comprises the first record of the genus Belenois in China and the highest altitude record of this species. New information The species B. aurota (Fabricius, 1793) is the first record of the genus Belenois from China. The specimen was collected at an altitude of about 3,000 m in Tibet Autonomous Region. Relevant details are presented for the species.


Introduction
The family Pieridae, which is a cosmopolitan family, includes over 1,000 species in 83 genera (Ackery et al. 1999, Braby 2005. The adults are of medium size and always sobre colour, typically white or yellow and with black or red patterns. Some species exhibit seasonal phenotypic variation (Braby 2005, Shou et al. 2006).
The genus Belenois Hübner, [1819] includes 29 species which are mainly found in the Ethiopian Region and there is only one species (Belenois java) that is distributed in the Oriental and Australian Realms. China is a country with mega-biodiversity, with new taxa and new records of butterflies discovered nearly every year in recent times (Hu and Zhang 2009, Hu and Zhang 2010, Hu et al. 2012a, Hu et al. 2012b, Zhang and Hu 2018, Zhang et al. 2020a, Zhang et al. 2020b. Even so, a large proportion of Chinese territory is still insufficiently surveyed. Belenois and Dixeia are sister groups and belong to the subtribe Aporiina of the tribe Pierini (Wahlberg et al. 2014). The genus Belenois was established by Hübner with Belenois calypso as its type-species. This genus has 29 known species which are mainly distributed in Africa and south-west Asia and also recorded in Oceania (Shou et al. 2006). However, there is no report of this genus occurring in China.
In this contribution, a well-known migratory species B. aurota (Fabricius, 1793) has been collected from Tibet Autonomous Region. The migration of the African colonies of this species almost every year has received lots of attention. The biology of B. aurota is also well studied. B. aurota larvae feed on plants of the family Capparidaceae, in particular the genus Capparis. Under some circumstances, the population erupts at local scale and defoliates the entire bush of Capparis; for example, in the Rwenzori National Park in Uganda, it has been a regular pest on C. decidua ( Chandra 1985). The specimens collected in this contribution are the first record of the genus Belenois from China.

Materials and methods
Photographs of the adult were taken with an interchangeable lens digital camera Olympus E-M1 with the lens M. ZUIKO DIGITAL ED 60 mm F2.8 Macro. After removal, the abdomen was soaked in 10% potassium hydroxide solution at room temperature for about 24 hours and was dissected under a Nikon SMZ18 microscope. The genitalia preparation was photographed by a Nikon D7500 digital camera attached to the microscope. Final plates were prepared in Adobe Photoshop CC (Adobe Systems Inc., San Jose, CA, USA). The specimen examined is deposited in the insect collection, Department of Forest Protection, Beijing Forestry University (BFU), Beijing.

Description
Male (Fig. 1). Forewing length 44 mm. Body blackish dorsally covered with grey hair and whitish ventrally. Antennae blackish, in typical club shape. Both wings white on the upperside, but with a creamy yellow hue on the underside. Wings with the following markings. Forewing upperside: costa grey, a short black band at the end of the discocell, a curved black subapical band running from costa to vein CuA and outwardly extending along veins to termen. Forewing underside similar to upperside, but all markings, especially the ones in the apical area, tinged with a golden-brown hue. Hindwing upperside: a black spot at the end of vein Sc+R , termen black fused with a series of subterminal black crescents before vein CuA . Hindwing underside: the previously-mentioned markings, all veins and a short discal band before vein Rs golden-brown. underside.
The first record of the genus Belenois (Lepidoptera: Pieridae) from China Male genitalia (Fig. 2). Highly sclerotised. Ring straight of moderate width; tegumen narrow in dorsal view; uncus broad at the base, but abruptly narrowed into the same width towards the tip in the dorsal view, while strongly curved ventrally in the lateral view. Saccus slender with a flattened tip. Valve triangulate, slightly elongated distally with an acutely pointed tip, with a long harpe running through the median part. Aedeagus slender and straight, with a pointed tip, Juxta fan-shaped in posterior view.

Distribution
South, Southeast and Central Asia; Tropical Africa; China (New record)

Discussion
Belenois aurota is found both in Asia and Africa, this species is migratory, the migration of the species in South Africa has received considerable attention in previous studies (Dickson andSchofield 1958, Taylor 1959), while, except for the populations of the Arabian Peninsula, few records of migration of the Asian populations have been observed; phylogenetic and phylogeographic patterns show that populations of Africa and Asia represent different clusters (Irungbam et al. 2019 We are more inclined to recognise this specimen as a stray butterfly based on its locationfar from the known distribution area and a single record for several decades. In previous studies, the Himalayan populations of B. aurota were mainly distributed in areas below 1,800 m, the highest altitude recorded for the distribution of this species being 2,400 m in Nilgiris, India (Bingham 1907, Cotton et al. 2015. However, in our field investigation, an individual of B. aurota was collected at an altitude of about 3,000 m which is the highest altitude record of this species. Colonies of an undetermined Capparis species were also found around Diya Township (Fig. 3); we speculate that this species might be Capparis himalayensis, which could be a suitable host plant for B. aurota larvae. Due to the existence of the host plant, we believe that our B. aurota specimen, collected in the Diya Township, was highly likely from a local population rather than a stray butterfly.