Megachile pluto Smith, 1860

Wood, T. J., Risch, S., Orr, M. C. & Hogan, J. E., 2025, An illustrated type catalogue of the bee species collected by Alfred Russel Wallace and described by Frederick Smith from Southeast Asia (Hymenoptera: Apoidea), European Journal of Taxonomy 1028, pp. 1-144 : 87-88

56. Megachile pluto Smith, 1860

Fig. 55

Megachile pluto Smith, 1860b: 133 , ♀.

Type material examined

Holotype

INDONESIA • ♀; Bac. [Bachian]; [ 21 Oct. 1858 – 13 Apr. 1859]; OUMNH, ENT-HYME2813 .

Type locality

Bachian [= Bacan].

Notes

The specimen is labelled “Bac. 59”. Examination of Wallace’s 5 th notebook ( Beccaloni 2025) reveals the following information:

“gigas! immense jaws,- flying round in mountain forest with loud beetle like hum!! Megachile pluto. Sm.!!!”.

Baker (1993: 212) wrote the following:

“ A ♀ labelled ‘Bac. 59’ [white disc] and ‘ Megachile Pluto. Smith’, in the UMO type collection, is the HOLOTYPE of this species. It is intact and in fair condition.

In view of recent mis-statements [e.g., in Messer, 1984] concerning the distribution and supposed endangered status of this species, commonly but erroneously referred to as the largest known species of bee, the following occurrences may be placed on record:-

Zuid Halmaheira [the ‘Noord’ of the printed label altered in ink], pre-1863 (H.A. Bernstein), ♀. Ternate, Ake Abdas, 1500 m., 1 ix 1951 (native collector), ♀.

NW Obi, Laiwui, 0- 200 m., 15 ix 1953 (A.M.R. Wegner), ♀ ”.

Baker did not give a repository for the records of M. pluto he listed, presumably targeted at Messer’s (1984: 165) statement that “The species, which is the world’s largest bee ( Michener, 1965), was previously known from only two specimens ( Friese, 1909), and presumed extinct ( Wells et al., 1983)”. Debate continues to surround this species, whether it genuinely is the largest bee in the world ( Michener 1965: 191), how rare it genuinely is, its current conservation status, and its current legal protection (e.g., Vereecken 2018). Whilst it now appears to be the case that it is present across the North Maluku islands, focused rather than sporadic sampling and monitoring efforts are needed to genuinely establish its current status. The OUMNH specimen has now been labelled as the holotype.

Current status

Megachile ( Callomegachile) pluto Smith, 1860 ( Ascher & Pickering 2024).

Distribution

Indonesia ( North Maluku: Bacan, Halmahera, Obi, Ternate, Tidor) ( Smith 1860b; Messer 1984; Baker 1993; Ascher & Pickering 2024). A recent Facebook posting indicates that M. pluto is also present on Morotai Island, broadening its distribution across the North Maluka region (MCO unpubl. data).