Studies on Schismatoglottideae (Araceae) of Peninsular Malaysia III: New species for the Schismatoglottis Calyptrata Clade

Three new colonial species of Schismatoglottis Calyptrata clade are described from Peninsular Malaysia and compared with the four already known morphologically similar species described from there. All seven species are illustrated from living plants and an identification key is provided.


INTRODUCTION
With the exclusion of Schismatoglottis calyptrata (Roxb.) Zol. & Moritzi (sensu Hay 1996;Hay in Hay and Yuzammi 2000) from the flora of Peninsular Malaysia Wong and Boyce 2020) the Schismatoglottis Calyptrata Clade  is currently represented in the Malay Peninsula by four described species: Schismatoglottis cordifolia Ridl. (Ridley 1911: 112; Figures 1 and 10B), S. guabatuensis S.Y.Wong & P.C.Boyce (Wong and Boyce 2020: 1; Figure 10C), S. lowiae S.Y.Wong & P.C.Boyce (Wong and Boyce 2017: 31;Figures 2 and 10E), and S. wallichii Hook.f. (Hooker 1893: 537;Figs. 3 and 10G). During pollination biology studies by the third author Hoe et al. 2018Hoe et al. , 2020Wong et al. 2016) it became evident that several populations encountered did not correspond to any of these four species, nor did they match any described species from Sumatera or further east. In conclusion we consider these populations to represent undescribed species and here describe three novel Peninsula Malaysian species belonging in the Calyptata clade. Geology in this paper is specified based on Tate et al. (2008).

Diagnosis
Schismatoglottis caesia is immediately differentiated from all other species of the Schismatoglottis Calyptrata clade by the glaucous pale grey leaf blades.

Etymology
The specific epithet is derived from the Latin noun, 'caesius', bluish grey, referring to the unique colouration of the leaf blades.

Distribution
Schismatoglottis caesia is only known from two populations in east Kelantan, separated by about 120 km.

Ecology
Perhumid lowland tropical forests, on alluvial sandstone-derived mud overlying Triassic granite, along track margins and on steep slopes along the margins of streams, 50-100 m asl.

Notes
The glaucous leaf blades of Schismatoglottis caesia are highly distinctive, even sterile juvenile plants are readily identifiable and immediately distinguished from the co-occurring S. lowiae. The type population occurs  adjacent to (although not associated with) Ordovician-Devonian Karst, suggesting that the species is not able to colonize karst. By the same token there are species in the Calyptrata clade (e.g., S. guabatuensis) that never occur away from limestone. Such geological obligations appear to be a contributing factor behind the high species diversity that aroids, and several other herbaceous and woody plant families, display in SE Asia (e.g., Wong

Diagnosis
Schismatoglottis laxipistillata is distinguished from the other species in the Calyptrata Clade by its laxly arranged pistils.

Distribution
Schismatoglottis laxipistillata is only known from its locality at Hutan Lipur Rekreasi Tupah where it is threatened by land clearance for quarrying.

Ecology
Perhumid lowland forest, occurring beside the margin of the waterfall and stream and restricted to steep Ordovician-Devonian Karst slopes in pockets of occasionally inundated mud. About 100 m asl.

Notes
Initially it was thought that the lax pistillate florets were an artefact of the first specimen encountered, but their occurrence is highly uniform through the known population.

Diagnosis
The spadix of Schismatoglottis pantiensis is superficially similar to that of S. lowiae differing by the pistillate zone extending to almost half the length of the spadix (vs about 1/3), by the interstice up to three times longer, and with the interstice staminodes and staminate florets readily distinguished (vs interstice staminodes and staminate florets almost indistinguishable until pollen is shed from the anthers), and consequently their respective zones easily discerned, and by a short bulletshaped appendix comprised of clearly individuated staminodes (vs appendix blunt-cylindrical with the individual staminodes not discernible.

Etymology
The specific epithet is derived from the name of the type locality plus the Latin suffix, -ensis, to indicate originating from.

Ecology
Lowland tropical forest on deep permanently moist podzols, below 25 m asl.