68 
Card. Bull. Singapore 69(1) 2017 
M. curvinervis is a synonym of M. macrophyllus (Korth.) Miq. However, we were 
unable to match the Ladan Hills taxon to any of the Macrosolen species preserved 
in BO, BRUN and SING. Barlow (1997) enumerated 24 species of Macrosolen in 
Malesia, and a survey of all the species listed in his revision reveals that only one 
taxon, Macrosolen brevitubus Barlow was reported to have linear leaves, but only at a 
juvenile stage. The leaf width measurement recorded for Macrosolen brevitubus at the 
juvenile stage was 0.5-1 cm wide (Barlow, 1995, 1997), while the Ladan Hills taxon 
differs in having much narrower leaf width at 0.1-0.2(-0.25) cm wide. Hence, the 
Ladan Hills population which maintains this extremely narrow leaf even when mature 
is distinct and described here as a new species. 
Materials and Methods 
A review of all the Bornean Macrosolen species was conducted based on herbarium 
specimens preserved in BO, BRUN and SING. Conventional methods employed in 
herbarium taxonomy were applied in this study. All measurements for vegetative 
characters were taken from dried herbarium specimens, w hil e measurements of 
reproductive structures were taken from materials preserved in spirit collection. 
Photographic documentation was taken in the field. Type materials present at SING 
were examined, as well as type images of all Malesian Macrosolen species available 
at JSTOR® Global Plants website (http://plants.jstor.org). Botanical terms used in this 
study largely follow Beentje (2012). Provisional conservation assessments are made 
using the methodology proposed by IUCN (2012). 
New species 
Macrosolen brunsing Y.W.Low & Ariffin, sp. nov. 
Similar to Macrosolen brevitubus Barlow but differs in having narrow linear leaves 
((4-)8-14.5 cm long, 0.1-0.2(-0.25) cm wide), and inflorescence a raceme of two 
opposite pairs of flowers. - TYPE: Brunei, Tutong District, Rambai, Ladan Hills 
Forest Reserve, Nyamokning Dam, BRUN-SING botanical exploration campsite on 
the edge of forest near water body, lowland mixed dipterocarp forest on yellow sandy 
clay soils, 04°23'35.6"N 114°48'58.6"E, 75 m asl, 22 August 2016, Y.W. Low, M.I. Siti 
Nur Bazilah, A.K. Muhd. Ariffin, A. Watu, E. Jangarun, P. Azlan, K. Muhd. Khairul 
Nizam & Z.A. Muhd. Wafiuddin LYW 1081 (holotype BRUN (including spirit material 
as part of a single specimen); isotypes E, K, L, SAN, SAR, SING [[SINGO166300] & 
spirit material [SING0202921]). (Fig. 1, 2) 
Aerial stem hemiparasitic shrub with epicortical runners bearing secondary haustoria, 
glabrous. Leaves opposite, rarely sub-opposite; petioles 1-2 mm long; lamina 
narrowly linear, (4—)8—14.5 cm long, 0.1—0.2(—0.25) cm wide, base truncate, apex 
narrowly acute, coriaceous; midrib inconspicuous and sunken above, prominent and 
