Colura sigmoidea Sangratt., Chantanaorr. & R.L.Zhu, 2019

Sangrattanaprasert, Jiroat, Chantanaorrapint, Sahut & Zhu, Rui-Liang, 2019, The genus Colura section Gamolepis (Lejeuneaceae, Marchantiophyta) in Malesian region, with the description of Colura sigmoidea, Phytotaxa 387 (1), pp. 40-54 : 43-44

Colura sigmoidea Sangratt., Chantanaorr. & R.L.Zhu , sp. nov. ( Figs. 3 & 4 )

Colura sigmoidea is similar to C. cristata but differs in having dioicous sexuality, ovate to lanceolate lobule sac ending with small laminar crest (consisting of 3–5 cells), small valves consisting of 30–40 cells, and basal median cells of valve adnate with one hinge cell to form together a sigmoid curve in outline.

Type: — MALAYSIA. Pahang State: Cameron highland district, Gunung Batu Brinchang , 04°30ʹ24ʺN, 101°23ʹ13.9ʺE, 1705 m. 15 February 2015, Sangrattanaprasert 263/15 C (holotype: PSU!; isotypes: BKF!, HSNU!) .

Plants pale green, 4–7 mm long; shoots 1–1.2 mm wide; irregularly pinnately branched, branches of the Lejeunea - type. Stems 55–80 μm in diameter, in transverse section consisting of 7 cortical cells (14–30 × 12–26 μm) and 3 medullary cells (12–18 × 6–10 μm); ventral merophytes of stem 2 cells wide. Rhizoids numerous, fasciculate at base of underleaves. Leaves remote, spreading from stem at 45°–50° angle. Lobes 0.59–1 mm long, 0.19–0.4 mm wide; dorsal margin entire. Lobe cells thin-walled, trigones large, intermediate thickenings distinct; marginal cells subquadrate to slightly rectangular, 18–30 × 14–22 μm; median cells rectangular to subquadrate, 22–38 × 14–22 μm; basal cells rectangular, 34–50 × 16–28 μm. Cuticle smooth. Oil bodies numerous per cell, homogenous to coarsely segmented, ellipsoid to spherical, 2–6 × 1–3 μm. Lobules narrowly tubular, flaring toward sac, 0.86–1.5 mm long. Lobule sacs ovate to lanceolate, strongly inflated, 0.44–0.8 mm long, 0.22–0.3 mm wide, sac surface mamillose, apex acute, ending in apical crest consisting of 3–5 cells, rarely entire. Valves intermediate-type, elliptic to ovate, 70–86 × 50–56 μm, composed of one circle of 17–21 hyaline marginal and 14–20 median cells with one basal median cell, basal median cell adnate with one hinge cell forming a sigmoid curve in outline. Hyaline papillae bulbous, (12–) 14(–16) μm in diameter. Valve frames outline semicircular with uniseriate cells, 80–115 μm wide. Underleaves distant, deeply bilobed, sinus obtuse; lobes lanceolate, 100–130 × 40–54 μm, 6–8 cells long, 3–4 cells wide at base; margin entire. Asexual reproduction by discoid gemmae, occurring on lobule sac apex and leaf lobe, sometimes on dorsal lobe of female bract; gemma cells subquadrate to isodiametric, consisting of ca. 24 cells.

Dioicous. Androecia terminal or intermediate on main stems and lateral branches; male bracts in 2–11 pairs, hemispherical, apical keel crenulate with one projecting cell row, free margin entire; bract lobes semicircular, 200–320 × 136–180 μm; bract lobules semicircular, 200–320 × 120–160 μm; antheridia 2 per bract; male bracteoles bilobed, 98–120 × 50–60 μm. Gynoecia terminal on lateral branches with 1 pycnolejeunoid innovation; female bracts obovate, 440–720 × 230–250 μm, apical keels crenulate with 1 projecting cell row; bract lobules narrowly oblong, 415–624 × 80–130 μm; female bracteoles bilobed, smaller than underleaf, 100–140 × 60–66 μm. Perianths oblong, ca 0.8 mm long, ca 0.44 mm wide, with 3 keels; keels short, ridged, entire or bearing small tooth at keel apex; beak 2–3 cells long. Sporophytes not seen.

Habitat and ecology: — Colura sigmoidea occurs on living palm leaves in lowland evergreen and montane forests at altitude between 200 and 1300 m. The species was associated with other epiphyllous liverworts, such as Cololejeunea dozyana ( Sande Lacoste (1855: 522)) Schiffner (1900: 199), C. grossepapillosa ( Horikawa (1932: 92)) Kitagawa (1981: 68), Colura acroloba , Drepanolejeunea pentadactyla ( Montagne (1848: 113)) Stephani (1913: 357), and Leptolejeunea foliicola Stephani (1896: 106) .

Distribution: — Colura sigmoidea is known only from Thai-Malay Peninsula.

Etymology: —The specific epithet “ sigmoidea ” refers to the adnation outline between basal median cell of valve and hinge cell of lobule.

Additional specimens examined: — MALAYSIA. Pahang Stage: Raub District, Fraser’s hill, 1230–1300 m, 8–11 April 2014, Sangrattanaprasert 75/14 B, 81/14 B, 82/14 B, 83/14 E ( PSU). Pahang Stage : Cameron highland district, Gunung Batu Brinchang , 04°30ʹ24ʺN, 101°23ʹ13.9ʺE, 1705 m, 15 February 2015, Sangrattanaprasert 265/15 ( PSU) ; Tanah Rata District , rainforest near downtown, 04°28ʹ1ʺN, 101°22ʹ41ʺE, 1460 m, 16 February 2015, Sangrattanaprasert 275/15 A, 277/15 C ( PSU) . THAILAND. Nakhon Si Thammarat Province: Phrom Khiri District, slope trail from Phrom Lok Peak to Phrom Lok Waterfall , on living leaves of palm, 08°32ʹ10.27ʺN, 099°45ʹ27.00ʺE, ca. 200 m, 23 April 2014, Sangrattanaprasert 105/14 B .

Taxonomic notes: —The characteristics of Colura sigmoidea : rather small plants 1–1.2 mm wide with leaves bearing ovate to lanceolate lobule sacs, the presence of apical crest at lobule sac apex, the basal median cell of valve adnate with hinge cells to form a sigmoid curve in outline, the dorsal leaf margin entire, the presence of crenulate projecting cells at keels of female bracts, and the presence of gemmae on the dorsal side of female bracts.

Colura sigmoidea is morphologically similar to C. cristata and C. verdoornii . The three species share many characteristics in apical crest of lobule sac, lobule sac surface, valve type, and others. However, Colura cristata is easily separated from C. sigmoidea by the autoicous sexuality, the elliptic lobule sacs with large apical crest consisting of 7–17 cells, large valve composed of 24–26 hyaline marginal and 31–33 median cells, and the basal median cell of valve fused with hinge cell not forming sigmoid curve. Colura verdoornii differs from C. sigmoidea in having the elliptic-ovate lobule sac, large elliptic valve (76–100 × 54–70 μm), and basal median cell of valve fused with hinge cell not forming sigmoid curve. The main morphological comparison between these three species are summarised in Table 1.

Figures

FIGURE 3. Colura sigmoidea Sangratt., Chantanaorr. & R.L.Zhu:A. Portion of plant with gynoecia, dorsal view. B. Portion of plant with androecia, ventral view. C. Stem in transverse section. D–E. Lateral leaves, D. ventral view, E. dorsal view with gemmae. F–G. Leaf lobe cells, F. median cells, G. marginal cells. H. Crest on the apex of lobule sac. I. Valve attached to valve frame. J. Valve (b = basal median cell, h = hinge cell, hy = hyaline papilla). K. Underleaf. L–M. Androecia, L. dorsal view, M. ventral view. N–O. Female bracts, N. dorsal view, O. ventral view. P. Female bracteole. Q. Perianth with bracts and bracteole. R. Perianth beak. A–B, N–R from Sangrattanaprasert 263/15C (PSU), C–K from Sangrattanaprasert 105/14 (PSU), L–M from Sangrattanaprasert 83/14E (PSU).

FIGURE 4. Colura sigmoidea Sangratt., Chantanaorr.& R.L.Zhu:A. Plant habit and habitat.B. Portion of plant with terminal androecium, dorsal view. C. Valve (b = basal median cell, h = hinge cell, hy = hyaline cell). D. Valve frame. E. Leaf, ventral side. F. Gemmae (g) occurring on dorsal side of female bract. G. Median cell of leaf lobe with oil bodies. A, C–G from Sangrattanaprasert 105/14B, B from Sangrattanaprasert 83/14E.