Orthiopteris samoensis P.H.Hovenkamp & T.T.Luong, 2015

Luong, Thien Tam, Hovenkamp, Peter H. & Sosef, Marc S. M., 2015, Revision of the fern genus Orthiopteris (Saccolomataceae) in Malesia and adjacent regions, PhytoKeys 53, pp. 39-71 : 56-57

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 × 15-20 cm, lanceolate; ultimate segments 1.0-2.0 × 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 × 0.4-0.9 mm. Sori lateral on lobes, symmetric, not reflexed, in one plane with lamina wings, 0.5-0.8 × 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. ¼ 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.

Figures

Figure 2. Ultimate segments. Arrows show distance from base of the shallowest sinuses to nearest costule / vein. a Orthiopteris ferulacea, Smith 8932 (K) b Orthiopteris cicutarioides, Carr 13257 (K) c Orthiopteris samoensis, Reinecke 97 a (L) d Orthiopteris trichophylla, Brass 12239 (L) e Orthiopteris campylura var. cautada, Carr 12518 (L) f Orthiopteris campylura var. laxa Mueller s. n. (L) g Orthiopteris campylura var. kingii, Brass 12941 (MICH) h Orthiopteris henriettae, Lam & Meeuse 5892 (L) i Orthiopteris campylura var. insularis Braithwaite 4110 (L). All scale bars 1 mm.

Figure 3. Sori of Orthiopteris seen from abaxial side. a, b Orthiopteris campylura var. campylura (Cuming 119, MICH) c Orthiopteris campylura var. kingii (Brass 12941, MICH) d Orthiopteris trichophylla (Brass 12239, L) e Orthiopteris tenuis (Smith 9154, L) f Orthiopteris tenuis (Smith 7274, L) g Orthiopteris campylura var. caudata (Carr 12518, L) h Orthiopteris cicutarioides (Carr 13257, K) i, j Orthiopteris campylura var. insularis (Braithwaite 4110, L) k Orthiopteris tenuis (small segment) (Degener 14648, L) l Orthiopteris ferulacea (Smith 8932, K) m, n Orthiopteris firma (Schlechter 14890, L) o, p Orthiopteris campylura var. laxa (Mueller s. n., L) q, r Orthiopteris henriettae (Lam & Meeuse 5892, L) s Orthiopteris henriettae. t Orthiopteris samoensis (Reinecke 97 a, L) u, v Orthiopteris samoensis (Vaupel 312, L). All scale bars 1 mm, oi = outer indusium, ii = inner indusium.

Figure 4. a-d Rhizome scales and e-h rachis scales of Orthiopteris. a Orthiopteris cicutarioides (Carr 13257, L) b Orthiopteris ferulacea (Smith 8932) c Orthiopteris firma (Green 1793, K) d Orthiopteris campylura var. kingi (Hoogland & Craven 10162, L) e, f Orthiopteris campylura var. kingi (Larhing 6910, L) g, h Orthiopteris samoensis (Reinecke 97 a, L). Scale bars: 1 mm (a-d), 0.1 mm (e-h).

Figure 6. Orthiopteris spores. a, b Orthiopteris firma (Guillaumin & Baumann-Bodenheim 10318, L) c Orthiopteris tenuis (Smith 9154, L) d Orthiopteris campylura var. campylura (Elmer 11717, L) e Orthiopteris campylura var. caudata (Ridsdale 30654, L) f Orthiopteris henriettae (Lam & Meeuse 5892, L) g, h Orthiopteris samoensis (Sledge 1563, L). All scale bars 10 µm.