Revision of the fern genus Orthiopteris (Saccolomataceae) in Malesia and adjacent regions Author Luong, Thien Tam Department of Ecology - Evolutionary Biology, Viet Nam National University Ho Chi Minh city (VNUHCM) - University of Science. 227 Nguyen Van Cu, Ho Chi Minh City, Vietnam & Naturalis Biodiversity Center, section Botany. PO Box 9517, 2300 RA Leiden, The Netherlands Author Hovenkamp, Peter H. Naturalis Biodiversity Center, section Botany. PO Box 9517, 2300 RA Leiden, The Netherlands Author Sosef, Marc S. M. Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium text PhytoKeys 2015 2015-07-21 53 39 71 http://dx.doi.org/10.3897/phytokeys.53.4955 journal article http://dx.doi.org/10.3897/phytokeys.53.4955 1314-2003-53-39 824BD167D1535A15FC27FF98FFD3A404 576284 6. Orthiopteris samoensis P.H.Hovenkamp & T.T.Luong spec. nov. Figs 2c , 3t , 3u, v , 4g, h , 6g, h Diagnosis . Differs from all other Orthiopteris species in relatively dense scales on lower surface of the lamina. Type. SAMOA. Savai'i , 31 December 1905, Vaupel 312 (holo: L, 3 sheets: L0319870, L0319927, L0319847, iso: MO, U). Description. Rhizome erect, rising at least 50 cm above ground, diameter unknown. Rhizome scales unknown. Fronds 150-200 cm (complete fronds not seen); stipes stout, ca. 70 cm long, 0.5-0.8 cm across (at base), light brown; lamina probably deltoid, quadripinnate, 100-150 cm long, at least 60 cm wide, firm- herbaceous, brownish green when dry, scaly with scattered scales on abaxial surface, denser at base of segments, and on veins and base of rachis; pinnae at 45-50° to rachis, separated or slightly overlapping, stalk 1.6 cm, including stalk up to 30-45 x 15-20 cm, lanceolate; ultimate segments 1.0-2.0 x 0.4-0.8 cm, sessile or very short stalked, narrowly trapezoid, apex obtuse to acute, margin with weak cartilaginous border; shallowly incised to 0.3-1.0 mm from veins; lobes obtuse to acute, veins in lobes form 3-6 forks, yellow green, weakly contrasting with lamina, percurrent. Scales on rachis irregularly triagular, basifixed, 0.4-1.4 x 0.4-0.9 mm. Sori lateral on lobes, symmetric, not reflexed, in one plane with lamina wings, 0.5-0.8 x 0.6-0.75 mm, suborbicular to funnelform, widest at mouth; inner indusium brown to dark brown, firm, slightly shorter or equal to outer indusium, rarely longer, apex with a rounded to truncate, 0.1-0.2 mm long lobe, eroded, ca. 1/4 length of sorus; outer indusium truncate, shallowly lobed or eroded; sporangia 5-10 per sorus, capsule globose and rounded at apex, gradually narrowed toward base, indurated annulus cells 17-19, clearly unequal; spores in polar view 30-33 µm , in lateral view 23-27 µm . Distribution. endemic to Samoa (Upolu, Savaii). Ecology. Terrestrial, medium wet forest, at 600-900m altitude Etymology. The specific epithet refers to the type locality. Discussion. The key character to separate this newly recognised species from the others are the many scales covering the abaxial surface of lamina. Orthiopteris campylura may have some scales on the lower lamina surface, but these are sparser, smaller and narrower. Apart from the laminal scales, Orthiopteris samoensis most closely resembles Orthiopteris campylura var. caudata in terms of frond and sori shape, but the inner indusia of Orthiopteris samoensis are not lobed.