| Ludlow's Bhutan Swallowtail | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Papilionidae |
| Genus: | Bhutanitis |
| Species: | B. ludlowi |
| Binomial name | |
| Bhutanitis ludlowi Gabriel 1942 |
|
Ludlow's Bhutan Swallowtail (Bhutanitis ludlowi) is a species of butterfly in the family Papilionidae. It belongs to the subfamily Parnasiinae which also contains the Apollo butterflies.
Until recently, Bhutanitis ludlowi was known from five specimens collected in Bhutan during 1933-1934 by the botanists Frank Ludlow and George Sheriff. Four of these specimens were referred to in the type description, which contained little information on the species' biology other than they were collected at an altitudinal range of 2000-2200 metres in forest. A second collection from China is claimed by Chou (1994), who illustrated a fresh specimen of B. ludlowi. Yunnan was cited as the collection locality. Although the validity of this record has been questioned by subsequent authors, B. ludlowi was still cited as occurring in Yunnan by Chou (2000). A distribution map for B. ludlowi in Coote (2000) also appears to designate southwestern Sechuan, China, as a locality. Although no reference is directly used to substantiate this record, references cited by Coote (2000) include a paper on Bhutanitis in China by Chou (1992). As Chou did not refer to Sechuan as a locality in subsequent publications on Bhutanitis (Chou 1994; Chou 2000), the source and validity of the Sechuan record needs clarification.
In August 2009, a Bhutanese forestry officer collected a specimen of B. ludlowi in the Bumdeling wildlife sanctuary, located in Bhutan's remote Trashiyangtse Valley. This specimen provided the first unambiguous evidence in some 75 years that the species was extant. In August 2011, some mating pairs of B. ludlowi were sighted and captured at Bumdelling Wildlife Sanctuary in Bhutan by research team from Bhutan in collaboration with the Butterfly Society of Japan (BSJ) and NHK Japan (Bhutan Government official release 2011; Kuenzang 2011). Amazingly, the expedition sighted their first B. ludlowi on August 12, the same date that Ludlow and Sherrif took the first specimen in 1933. Thanks to the rediscovery of the butterfly on the expedition, B. ludlowi became the national butterfly of Bhutan.
The 2011 expedition also revealed considerable biological information about B. ludlowi (Choden, 2011). Its hostplant is Aristolochia griffithi, which is also utilised as a hostplant by other Bhutanitis taxa. Bhutanitis ludlowi eggs are smaller than in other Bhutanitis and are laid on top of each other in a stacked pile arrangement. Video footage of live adults (external links 3 and 4) show that their flight is rapid with a deep wingbeat and frequent gliding. The forewings provide all propulsion, while the hindwings are unpowered during normal flight and trail behind the butterfly. Unlike many swallowtail butterflies, B. ludlowi does not continuously flutter its wings while feeding. Viburnum cylindricum flowers were the most commonly used adult food source.
As so few specimens are known, B. ludlowi is rarely illustrated. It is similar in appearance to the allied B. lidderdalii but has broader wings with the transverse bands grey instead of white (Chou, 2000). The distribution of both B. ludlowi and B. lidderdalii may overlap in Bhutan and Yunnan, China (Chou 2000), although it is unknown whether they co-occur in the same habitat.
As with all other members of the genus Bhutanitis, B. ludlowi is listed on Appendix II of CITES, restricting any international trade. As of 2011, there were no reports of the species having entered trade, but it is highly sought after by collectors. Its most recent IUCN assessment is Vulnerable (Gimenez Dixon, 1996). Although collecting butterflies in Bhutan is prohibited, the BSJ is building butterfly rearing capacity with the Bhutanese government for B. ludlowi and other species. Sustainable commercial rearing of this species has potential to eliminate the need for specimens to be continually harvested from wild populations, or to at least reduce the impact of harvesting so it is negligible. As with similar butterfly ranching programs in Indonesia and Papua New Guinea, sustainable harvesting may also provide wealth to remote communities with few other sources of legitimite income.