Rhapis subtilis subsp. subtilis

Henderson, Andrew, 2016, A revision of Rhapis (Arecaceae), Phytotaxa 258 (2), pp. 137-152 : 149

10a. Rhapis subtilis subsp. subtilis

Abaxial hastula usually incomplete, part of the petiole continuous with the costa; central segments 18.2(9.0–23.5) cm long, free almost to the base or joined at the base.

Distribution and habitat:—Central Laos, south-central Thailand, and western Cambodia ( Fig. 5 ) in lowland forest or riparian forest on granitic soils at 219(30–500) m elevation.

Taxonomic notes:— The type specimen of Rhapis subtilis , from central Laos, as well as another specimen (El Colani s.n. at P) from near there are here considered conspecific with specimens from further south in Thailand and Cambodia. However, these two northern, outlying specimens differ somewhat from those from further south in their shorter petioles and less numerous segments which are free to the base (versus usually joined at the base). More specimens from central Laos are needed to test for differences between the two populations.

Hodel (1998) noted that subsp. subtilis (as R. subtilis ) occurs in riparian or rheophytic habitats on granite soils and forms tight clumps, whereas subsp. siamensis (as R. siamensis ) occurs on limestone rocks and forms loose colonies by rhizomes.

Figures

FIGURE 5. Distribution maps of Rhapis robusta, R. subtilis subsp. subtilis, R. subtilis subsp. siamensis, and R. vidalii.