Heteroscyphus supinopsis J. J. Engel, Thouvenot & Frank Mull.

Heteroscyphus supinopsis J.J.Engel, Thouvenot & Frank Müll. (Fig. 22)

Nova Hedwigia 113: 62 (Engel et al. 2021).

—

Type: New Caledo-nia. South Province, Mt. Ouin, epiphytic in mossy forest, c. 900 m, 1.IX.2003, Müller NC797 (holo-, DR; iso-, F, hb. Thouvenot).

DISTRIBUTION IN NEW CALEDONIA. — Only known from the type specimen in South Province.

TOTAL RANGE. — Endemic.

Further description and illustrations in Engel et al. (2021). Dioecious.

Plant medium sized, rather rigid, 2.8-3.8 mm wide when flattened; ventral intercalary branching infrequent; stem narrow for plant size, 0.15-0.20 mm wide; leaves subopposite, horizontal grading to obliquely dorsally assurgent, weakly to moderately convex in dorsal sector, moderately abaxially concave in ventral sector, loosely imbricate, the dorsal leaf bases connate and forming a laminar lip to c. 6 cells wide.

1.30-1.80 mm long, 0.80-1.40 mm wide, subsymmetrical, mostly lingulate occasionally ovate to trapezoid, widest near the insertion; apex variable: broadly rounded to truncate, often retuse, sporadically short bilobed with lobe apices rounded to broadly acute, otherwise entire; margins straight or nearly so, entire.

25-35 µm wide, 30-40 µm long, somewhat larger near the base; in median portion of leaves with knot-like trigones that are separated by narrow, thin-walled places.

3.8-6.5 times the stem width, connate with the leaves on both sides, imbricate, stoutly ovate to subreniform, 0.6-0.9 mm long, 0.6-0.8 mm wide; apex bifid to (0.2)0.35-0.55, the lobes ± parallel to weakly divergent, acuminate from a broad base, entire or with a tooth toward base of outer margin; lamina 9-12 cells high and c. 2-5 times wider than long, the margins on each side with 1-5 dentiform to subciliiiform to occasionnaly laciniiform processes.

Gynoecia seen only in juvenile state, at the end of short leafless branches, lateral-intercalary, bracts ciliate to laciniate; androecia not seen.

Heteroscyphus supinopsis resembles H. supinus of New Zealand and Tasmania and H. deplanche i of New Caledonia. Like these species it is easily separated from other New Caledonian Lophocoleaceae by: 1) leaves usually lingulate with the apices and lateral margins entire; 2) cells with conspicuous trigones; 3) large underleaves wider than long with apices deeply bifid and margins armed with processes laciniate to dentiform. Heteroscyphus supinopsis is separated from the former by: 1) leaves distinctly connate dorsally; and 2) underleaves less deeply bifid (to 0.35-0.55 vs 0.8), underleaf discs longer (9-12 cells high at insertion vs 4-7) and less transversally elongate (2-5 times wider than long vs 7). It can be distinguished from the latter by: 1) its smaller size with shoots up to 3.8 mm when flattened vs 5 mm; 2) the absence of shoot segments with emarginate to bifid leaves; 3) shorter lateral processes on the underleaf margins, toothed to ciliate vs long laciniate; and 4) less robust stems with c. 40 cells in diameter vs up to 100.