Plaubelia involuta (Magill) R.H.Zander

Plaubelia involuta (Magill) R.H.Zander View in CoL

( Fig. 4 View FIG )

In Bulletin oF the Buffalo Society oF Natural Sciences 32: 176 (1993). — Weisiopsis involuta Magill View in CoL , 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).