Pleurozia acinosa (Mitt.) Trevisan (1877: 412)

Sukkharak, Phiangphak, 2017, A revision of the genus Pleurozia (Marchantiophyta: Pleuroziaceae) in Thailand and little known morphological features of the genus, Phytotaxa 309 (3), pp. 201-216 : 206

1. Pleurozia acinosa (Mitt.) Trevisan (1877: 412) .

Basionym:— Physiotium acinosum Mitten (1860: 102) . Type: SRI LANKA. Adam’s peak: 1846, Gardner 136 (lectotype, designated by Thiers 1993, NY; isolectotypes, BM) ( Thiers 1993).

= Pleurozia myriangium (De Not.) Trevisan (1877: 412) . Physiotium myriangium De Notaris (1876: 305) ( Thiers 1993).

= Physiotium heterophyllum Jack (1886: 82) , nom. inval. ( Thiers 1993).

Description:—( Figs. 1−3 ). Plants autoicous ( Thiers 1993), creeping, prostrate stems dominant, giving rise to short, multibranched upright stems bearing sterile gynoecia or fertile gynoecia; up to 1.5 cm long, 0.4−1.9 mm wide. Simple leaves dominant on vegetative branches and bases of upright branches, ovate, concave, 0.8−2.5 × 0.6−2.7 mm, apex acute to rounded, margins entire, base auriculate. Explanate-lobuled leaves not found (rare to common on branches bearing sterile gynoecia or fertile gynoecia in Thiers 1993). Saccate-lobuled leaves common on branches bearing sterile or fertile gynoecia; ventral lobes ovate, 2.1−2.3 × 1.2−1.3 mm, strongly concave, apex acute, margins entire, incurved, base auriculate; apical cells quadrate, 22−30 × 22−27 μm, marginal cells quadrate, 27−41 × 25−30 μm, median cells quadrate to rectangular, 50−61 × 41−47 μm, basal cells rectangular, 69−94 × 33−41 μm; dorsal lobules elliptical, 2−2.1 × 0.8−0.9 mm, aperture complex acinosa - type (subapical, basin oblong, lip discontinuous, overarching basin on proximal side); keel smooth, without appendage on neither side of stem. Androecia not seen. Fertile gynoecia terminal, bracts 0.7−1 × 3−3.3 mm, trilobed, lobes extending 1/2× bract length, lobes ovate, apices acute, margins entire; perianths lanceolate, tapering from near base to a small mouth, 5.0−6.0 × 1.75−2.0 mm, plicate in the upper 1/3, mouth ciliate. Sterile gynoecia terminal; bracts 0.4−0.9 × 4−4.2 mm, trilobed, lobes extending 1/2× bract length, lobes triangular, apices acute, margins entire, incurved; perianths oblong, 3−6.5 × 1.8−2.3 mm, mouth entire.

Additional illustrations:— De Notaris (1876: Tav. XXXIV as Physiotium myriangium ); Jack (1886: Tab. IX. Figs. 1 −16 as Physiotium acinosum ); Thiers (1993: Figs. 31–37); Bai & Li (1998: Fig. 1 : 1–7).

Ecology:— 1740–2500 m; on branches in evergreen forests.

Representative specimens:— Chiang Mai. INTHANON MT.: summit region, Tagawa & Kitagawa T2910 (BCU).— Nakhon Si Thammarat. KHAO LUANG: summit region, 8°30’ N 99°45’ E, Touw 11765 (BKF).

Additional distribution in Thailand:— Nakhon Si Thammarat. Tagawa & Kitagawa T4960 (G, NY) ( Thiers 1993).

Distribution:— Sri Lanka, China, Japan, Taiwan, Thailand, Malaysia, Indonesia, Philippines ( Thiers 1993).

Taxonomic notes:— The species is well distinguished and easily recognized from other species of Pleurozia in Thailand by its entire gynoecial bract margins and the absence of appendages on the keel of the dorsal lobule.

Figures

FIGURE 1. Pleurozia acinosa. A. Branch with saccate-lobuled leaves, dorsal view. B. Branch with saccate-lobuled leaves, ventral view. C. Saccate-lobuled leaves. D. Branch with simple leaves and gynoecium, dorsal view. E. Branch with simple leaves and gynoecium, ventral view. F. Simple leaves. [All from Touw 11765 (BKF)].

FIGURE 2. Pleurozia acinosa. A. Branch with sterile gynoecia, dorsal view. B. Branch with sterile gynoecia, ventral view. C. Bract of sterile perianth. D. Sterile perianth, dorsal view. E. Sterile perianth, ventral view. [All from Touw 11765 (BKF)].

FIGURE 3. Pleurozia acinosa. A. Bract of fertile perianth. B. Fertile perianth, dorsal view. C. Fertile perianth, ventral view. D. Apical cells of ventral lobe. E. Marginal cells of ventral lobe. F. Median cells of ventral lobe. G. Basal cells of ventral lobe. [All from Touw 11765 (BKF)].