A contribution to the systematics of Xylopia (Annonaceae) in Southeast Asia
Summary (2 min read)
Introduction
- The Annonaceae, a flowering plant family of 2500 species, including the economically important soursop, custard apple and ylang-ylang, is widespread across the tropics.
- Corlett & Turner (1997) determined that Annonaceae ranked fourth in species-richness among flowering plant families in Singapore; Appanah et al. (1993) found that Annonaceae ranked first in species diversity among lianas of Malaysian forests.
- A full treatment, including keys and distribution maps, is forthcoming.
- Conservation assessments using IUCN (2012) criteria are not included in this account as more data are required for these than the authors currently have available.
Xylopia ferruginea group
- The Xylopia ferruginea group is characterised by stilt roots, relatively long (5-19 mm) flower pedicels, a flat receptacle lacking a staminal cone (Fig. 2K ), flat narrowly oblong stamens with a tongue-shaped apex to the anther connective (Fig. 2J ), stigmas studded with small papillae (Fig. 2I ), and rugose seeds (Fig. 2C-D ).
- Seeds in a single row, parallel to long axis of monocarp, 6-12 per monocarp, 7.2-8.8 mm long, 5.5-5.6 mm wide, 4.7-5.1 mm thick, ellipsoid, elliptic in cross section, dark brown, rugose, flattened or a little concave at micropylar end, rounded at chalazal end, raphe and antiraphe distinctly raised; aril and aril plate absent.
- The bulk of the Sarawak and Brunei collections have come from either lowland peat swamp forest or heath forest (terminology following Saw, 2010) .
- These features are frequent in Sumatran specimens of Xylopia ferruginea s.s., which in general have larger and broader leaves than those of Peninsular Malaysian and Bornean plants, as well as a tendency toward a subcordate rather than truncate leaf base.
- The leaves are retuse at the apex and broadly cuneate and decurrent at the base.
Xylopia malayana group
- Species of the Xylopia malayana group are distinctive and well circumscribed with the exception of X. elliptica and X. malayana.
- The protologue, reproduced verbatim below, shows that the diagnosis emphasised the glabrous branches, the small elliptic, obtuse, membranous, glabrous leaves and the solitary flowers: 14.
- X. elliptica, Maingay mss.; branches glabrous, leaves small elliptic obtuse membranous glabrous, tip rounded, nerves faint reticulate, flowers small solitary erect pubescent, sepals subacute united to the middle, ovaries 1-3.
- Ridley (1922) subsequently maintained King's concept of the species intact.
Xylopia platycarpa
- Restricted to a small area of southern Thailand and northwestern Peninsular Malaysia.
- All localities are in lowland evergreen forest.
- Flowers in July and August, fruit collected in July.
Local name. Kerangi lotong (Kedah: Awang 42444).
- The species is named for its unusually flattened and beanlike monocarps.
- Twigs dark brown to brownish grey, eventually lenticellate, glabrous or finely but sparsely pubescent and soon glabrate; double-branching occasional.
- Material of this species is usually identified in herbarium collections as Xylopia malayana, but X. ngii differs consistently from that species in its smaller (2-2.9 mm long) sepals sparsely covered with pale brown pubescence and the longer (13.5-34.2 mm) and narrower (1-1.6 mm wide at the midpoint) outer petals.
Distribution
- The leaf blades are relatively small and oblong, often with a blotchy mottled appearance to the adaxial leaf blade surface when dried.
- Malaysia, Negeri Sembilan, Kuala Pilah, Pasoh F.R., Compt, also known as -TYPE.
- To confuse things further, this specimen was identified in turn as both Xylopia elliptica and X. malayana in the same publication by Corner (1978) .
Conclusion
- Six species are widespread across the Malay Peninsula, Sumatra and Borneo: Xylopia caudata Wall. ex Hook.f. & Thomson, X. ferruginea, X. fusca, X. malayana, X. ngii and X. sumatrana.
- Two species are shared between the Malay Peninsula and Borneo: Xylopia erythrodactyla and X. magna.
- Several species are large trees more than 40 meters in height, and this, coupled with sparseness of individuals in populations, may cause them to be overlooked.
- This explanation accords well with the extraordinary diversity of the genus found at sites such as the Pasoh Reserve, where in 2014 the authors verified the occurrence of seven Xylopia species in or near the Pasoh permanent 50-hectare research plot (Manokaran et al., 1992) .
- The authors results make clear, however, that further collecting and taxonomic analysis of the Malay Peninsula flora is still critically needed.
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Cites background from "A contribution to the systematics o..."
...This section is represented by 34 species in tropical Africa (Johnson & Murray 2018), 23 species on Madagascar, and c. 40 species in Southeast Asia. noteS Many of the sect....
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...Variation in climatic conditions in South and Southeast Asia from the early Miocene onward (Morley 2018), would, however, have permitted intermittent migration of Xylopia eastward, with the genus ultimately reaching New Caledonia and Fiji by long-distance dispersal (Johnson et al. 2013)....
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...Rugosperma D.M. Johnson & N.A. Murray (Asia), sect....
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...In conclusion, Madagascar may have played a role in the dispersal of the Stenoxylopia clade into Asia, but there is no current evidence, morphological, fossil, or molecular, to suggest that the sect....
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...Densely lenticellate oblong woody monocarps are unique among Madagascar Xylopia species, and rare in the genus, although this fruit morphology is known in species such as X. hypolampra in Africa (Johnson & Murray 2018) and X. ngii in Asia (Johnson & Murray 2015)....
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References
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"A contribution to the systematics o..." refers background in this paper
...Our results make clear, however, that further collecting and taxonomic analysis of the Malay Peninsula flora is still critically needed....
[...]
...Six species are widespread across the Malay Peninsula, Sumatra and Borneo: Xylopia caudata Wall. ex Hook.f. & Thomson, X. ferruginea, X. fusca, X. malayana, X. ngii and X. sumatrana....
[...]
...Two species are shared between the Malay Peninsula and Borneo: Xylopia erythrodactyla and X. magna....
[...]
...Xylopia elliptica, X. platycarpa, X. sessiliflora and X. subdehiscens (King) J. Sincl. are known only from the Malay Peninsula, and Xylopia coriifolia Ridl., X. kuchingensis I.M.Turner & D.M.Johnson, X. mucronata Boerl., X. orestera I.M.Turner & D.M.Johnson and X. pulchella Ridl. are unique to Borneo....
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...Two species are shared between the Malay Peninsula and Sumatra: X. dicarpa Hook.f. & Thomson and X. oxyantha (Wall. ex Hook.f. & Thomson) Hook.f. & Thomson....
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132 citations
"A contribution to the systematics o..." refers background or methods in this paper
...…with X. elliptica and even with X. fusca Maingay ex Hook.f. & Thomson: the specimens Wray 3562 and Yeob 5037 were identified as X. elliptica by Sinclair (1955), the specimens Ambriansyah & Arifin AA 891, Ambriansyah & Arifin W 801, and Ambriansyah & Arifin W 1007 were identified as X.…...
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...Gen. Pl. 8, 1891, which is based on Parartabotrys sumatranus Miq., now considered a taxonomic synonym of Xylopia malayana (Sinclair, 1955; Turner, 2011)....
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...The Curtis specimen, cited here as belonging to Xylopia platycarpa, was identified by King (1892), Ridley (1922), and Sinclair (1955) as Xylopia elliptica, but we found that it differs from the type of that name by its distinctly pubescent twigs and leaves, the leaves lanceolate rather than…...
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...MALAYSIA: Peninsular: Kedah: Perangin Forest Reserve, 30 Jul 1938 (fl), Awang 42444 ([Sinclair cites specimen at K, but this was not found in July 2014], KEP); Penang: Sungei Penang, Aug 1890 (fl), Curtis 2482 (BM, CAL (Sinclair, 1955), K, SING [2 sheets], US)....
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...Cantley 5842 (SING); Pahang: Tasek Bera FR, 22 Jul 1972 (fl), Chan FRI 16942 (A, K, KEP, L, SAR, SING); Perak: Without definite locality, without date (bud), Wray 3194 (CAL (Sinclair, 1955), SING [2 sheets])....
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