Whither Polyalthia ( Annonaceae ) in Peninsular Malaysia ? Synopses of Huberantha , Maasia , Monoon and Polyalthia s . s .

An updated classification of Polyalthia in Peninsular Malaysia is presented. A synopsis (listing of species with synonymy and typification, and keys to species) is presented for the genera Huberantha, Maasia, Monoon and Polyalthia sensu stricto. One new species (Polyalthia pakdin I.M.Turner & Utteridge sp. nov.) is described and a conservation assessment presented for it. Monoon xanthopetalum Merr. represents a new record for Peninsular Malaysia. Six new lectotypes are designated.


Introduction
When Sinclair (1955) revised the Annonaceae of the Malay Peninsula he recognised 32 species of Polyalthia Blume (including Polyalthia evecta Finet & Gagnep.from Peninsular Thailand still unrecorded from Peninsular Malaysia, and the cultivated Polyalthia longifolia (Sonn.)Thwaites).The 30 native species made Polyalthia the largest genus in the family as represented in the Malayan flora.The genus was characterised by Sinclair largely in terms of floral morphology including subequal corolla whorls of spreading, relatively flat, petals, numerous flat-topped stamens and many carpels with 1-5 ovules each.Sinclair considered the genus to be divisible into two sections that he called 'Polyalthia section Eu-Polyalthia' (correctly Polyalthia section Polyalthia) and Polyalthia section Monoon (Miq.)Benth.& Hook.f.Sinclair appeared confident in the classification, noting the Polyalthia was a large genus 'but very uniform'.However, in recent years the homogeneity of Polyalthia has come under close scrutiny with a growing conviction that it represented an unnatural grouping.Molecular analyses have confirmed the polyphyletic nature of Polyalthia sensu lato leading to a process of dismemberment as species have been transferred to various different genera.Of relevance to the species included in Polyalthia by Sinclair, section Monoon has been raised again to generic rank (Xue et al. 2012) (14 spp. of Sinclair's native Polyalthia species) and includes Enicosanthum Becc.(7 spp. recognised by Sinclair).Three of Sinclair's section Monoon species are now recognised in the new genus Maasia Mols et al. (Mols et al. 2008) and two in Huberantha Chaowasku in Chaowasku et al. [Chaowasku et al. 2015, originally named Hubera Chaowasku in Chaowasku et al. (Chaowasku et al. 2012) (1955: 321), Kochummen (1972: 88), Rogstad (1989: 209-212), Turner (2014: 74-75).

Remarks
Note that Polyalthia sumatrana var.macrocarpa was described from a mixed collection.Fruiting material of Monoon anomalum was confused with foliage of Maasia sumatrana.As the diagnosis focused on the characters of the fruits, we here designate the fruiting material as lectotype and exclude the foliage material.

Remarks
In studying material of Monoon from Peninsular Malaysia a group of specimens was found that did not match any of the species recorded from this area.The specimens were notable for the persistent goldenbrown tomentum on the twigs, the often dark brown shade of the dry leaves, petals linear-lanceolate c. 4 cm long and c. 5 mm wide, monocarps ellipsoidal, covered with a short dense pale brown tomentum with the stipe attached slightly eccentrically giving a similar appearance to those of some Uvaria species previously included in the genus Ellipeia.One of us (IMT) having worked on the Borneo species (Turner 2014)

Distribution and habitat
Recorded from the eastern side of Peninsular Malaysia from Kelantan and, with most records, Trengganu (Fig. 2).It occurs in lowland tropical rain forest.

Conservation status
Polyalthia pakdin sp.nov. is restricted to the lowland forests of eastern Peninsular Malaysia and currently known from seven collections from five localities (two are from the Sekayu area and two from Jambu Bongkok).The Extent of Occurrence (EOO) is 1,856 km 2 falling within the Endangered (EN) threshold of less than 5,000 km 2 , and the Area of Occupancy (AOO; based on a user-defined cell width of 2 km) is 28 km 2 falling within the Endangered (EN) threshold.Whilst none of the collections is contemporary (the most recent is 1972), nearly all are from forests reserves, and, in addition, one collection is from 'roadside forest' (J.Sinclair & Kiah bin Salleh SFN 40941).Whilst the EOO is within the EN threshold, the presence of the species within protected areas would not place the species within this category because recent satellite imagery shows the protected areas still with relatively large areas of intact forest (using the most recent Google Earth imagery).The Sekayu collections, for example, are on the edge of the very poorly known and under-collected Taman Negara National Park and more field collections are needed in such areas to better understand the distribution of this species.Without any other information, we must assume that the species is still present in these protected areas and that the protected areas still harbour the appropriate habitat for P. pakdin sp.nov.It is difficult to demonstrate trends in the reduction of habitat etc. without modern collections, and for these reasons we assign a preliminary conservation assessment of Near Threatened (NT).

Affinities
Polyalthia bullata, the species with which P. pakdin sp.nov.was formerly confused, was included in the informal group of Polyalthia species termed the Polyalthia insignis group by Johnson & Murray (1999).They characterised the group as follows: shrubs or small trees; leaves oblique, subcordate or auriculate at base, often drying grey above, brown below; inflorescences internodal to leaf opposed or sometimes cauliflorous; petals orange or red; apex of ovary woody and persistant as a short beak on the monocarp; stigmas capitate and cohering to drop as a cap at the end of anthesis, several ovules per carpel, laterally attached in vertical row and seed not pitted but with encircling groove.While Polyalthia pakdin sp.nov.does exhibit some of these characters, it does not have auriculate or cordate leaf bases and the stigmas do not seem to cohere.In fact, P. pakdin sp.nov.also comes close to the Bornean Polyalthia polyphlebia Diels which was not included in the P. insignis group by Johnson & Murray.The leaf form of P. pakdin sp.nov.and P. polyphlebia are similar but P. polyphlebia generally has greyish corky twigs, longer pedicels (8-15 versus 2-8 mm) with the flowers larger (outer petals 13-14 mm versus 6-10 mm) and the petals fleshy rather than thin in texture; with the monocarps on longer stipes (to 25 mm versus 6 mm).intervening 60 years which is perhaps fewer than might be expected and must reflect Sinclair's thorough study of the specimens available to him.There have been a large number of name changes, with fewer than half the species still having the same accepted name -all in Polyalthia s.s.The reason for this is primarily to create a more phylogenetically accurate taxonomy.It is clear that Polyalthia sensu lato was heterogeneous: uniting species with a roughly similar floral morphology.Users of taxonomy, such as foresters and ecologists, generally dislike name changes so there may not be much enthusiasm from them after these changes.The splitting up of Polyalthia will possibly have some practical advantages as large genera can be unwieldy and daunting to non-specialists.However, expanding the list of genera in a family that already has a large number to deal with may also discourage the users of taxonomy.Fortunately in this case, one of the three 'new' genera -Maasia -is easy to recognise because of the white or glaucous underside to the leaves giving a consistent gestallt to specimens that is soon learnt.

Polyalthia parviflora
Monoon and Polyalthia sensu stricto can be distinguished fairly readily, though some would doubtless have preferred the continued use of Enicosanthum rather than the resurrection of Monoon.
, the specimens were reminiscent of Monoon xanthopetalum Merr.Comparison of the specimens from Peninsular Malaysia with collections from Borneo (cf.Turner 2014: Fig.26) produced a close match.We have no doubt that Monoon xanthopetalum does occur in Peninsular Malaysia, representing a major range extension for the species.It is interesting to note that the Peninsular Malaysia collections of M. xanthopetalum are all from the East Coast which fits with the presence of the species in Borneo.