Plaubelia involuta (Magill) R.H.Zander

Taha, Mai A., Shabbara, Hanaa M. & Aseeri, Manal M., 2020, New Pottiaceae genera to the moss flora of Saudi Arabia and the Arabian Peninsula, Cryptogamie, Bryologie 20 (1), pp. 1-9 : 8

Plaubelia involuta (Magill) R.H.Zander

( Fig. 4 )

In Bulletin oF the Buffalo Society oF Natural Sciences 32: 176 (1993). — Weisiopsis involuta Magill , Flora oF Southern AFrica, Bryophyta 1: 225 (1981).

SPECIMEN EXAMINED. — Saudi Arabia. Asir region, Muhayil Asir governorate, Qana; 18°29’676’’N, 41°57’000’’E; 427 m a.s.l.; grow on the side of the valley; soil thickness 7 mm; slope slop; 25.X.2011, 23.I.2012, 24.IV.2012, 26.VI.2012; air moisture 57, 65, 54, 29 respectively; leg. Manal Aseeri; 131 Ma-d (CAIA).

DISTRIBUTION. — In Africa; Botswana, Namibia and in Asia; South west China ( O’Shea 2006; Cao et al. 2010).

New to the Arabian Peninsula

FLORISTIC ELEMENT. — Palaeotropical element.

FLORISTIC REMARKS. — Plaubelia Bird. was recorded previously by Shabbara (2006) from Isthmic Desert (North Sinai), Egypt as P. sprengelii (Schwägr.) R.H.Zander. But this is the first record of P. involuta in the Arabian Peninsula.

DESCRIPTION

Plants

Yellowish green 2 mm high.

Stem

Simple, central strand present, sclerodermis well developed.

Leaves

Imbricate crisped when dry, open spreading when wet; broad oblong spathulate, 0.6-1.2 mm long, 0.03-0.5 mm wide; apex rounded; margins more or less incurved above, plane below, adaxial surface cells bulging, mamillose to simple papillose; costa ending up to 8 cells below the apex; single abaxial stereid band; upper lamina cells incrassate, ventrally convex and dorsally nearly flat, rounded or irregularly quadrate (5-) 7-10 µm long and wide; basal lamina cells more or less hyaline, sub quadrate to rectangular, 10-27 µm long, 9-15 µm wide, smooth.

Propagules

Rarely present, axillary, oval shape, multicellular.

Comment

Propagules are very rare in the studied Plaubelia involuta samples; although common found by both Magill (1981) and Zander (1993). According to Magill (1981) this species is known only from northern Botswana. The type locality is a near-vertical, soft, crumbly calcrete cliff along the Botei River. Thus, the rarity of gemmae in the studied samples may be attributed to the drier habitats here ( Dolnik 2006).

Figures

FIG. 4. — Plaubelia involuta (Magill) R.H.Zander: A, dry plant; B, wet plant; C-F, leaves;G, upper part of leaf; H, basal part of leaf;I-K, leaf cross sections; L, stem cross section; M, axillary propagule. Scale bars: A-F, 0,3 mm; G, I-M, 50 μm; H, 100 μm.