Heteroscyphus subacuminatus (Herzog) Thouvenot, 2023

Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, Cryptogamie, Bryologie 20 (1), pp. 1-60 : 36-37

Heteroscyphus subacuminatus (Herzog) Thouvenot , comb. nov.

( Figs 19 ; 20 )

Chiloscyphus subacuminatus Herzog, Arkiv för Botanik, n.s. 3 (3): 49 ( Herzog 1953).

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Type: New Caledonia. Slope above N. branch of the Yaté River , near the Forêt du Mois de Mai , 8.VII.1949, Selling B144 p.p., not seen.

SPECIMEN EXAMINED. — New Caledonia. North Province, Poindimié, Amoa valley , Tipwadabwé , on rocks along the trail when crossing a flooding creek, 211 m, 13.X.2019, Thouvenot NC2740.

DISTRIBUTION IN NEW CALEDONIA. — Rarely collected in both provinces of the main island, Grande Terre, at low elevation.

TOTAL RANGE. — Endemic.

DESCRIPTION

Dioecious.

Habit

Plants fragile, light olive green, brown in older parts, large shoots 3.50-4.50 mm wide, leaves subopposite, secund, dorsal margins conspicuously connate over the stem, dorsally assurgent at least in upper parts of the shoots, the lowest horizontally spreading.

Leaves

Leaf shape asymmetrically ovate acuminate, 2.00- 2.50 mm long, 1.30-1.70 mm wide, ventral margins rounded in lower 2/3-3/4, dorsal margin nearly right, apices widely acuminate, acute to narrowly rounded, rarely bifid, frequently broken ( Fig. 20C, D ).

Cells

Leaf cells hexagonal, 30-50 µm wide, walls thin with large subacute trigones, cell lumina round to ovate.

Underleaves

Narrowly connate to both nearest leaves, 0.75-1.00 mm long, 1.20-1.50 mm wide, the disc rounded with widely wedgeshaped bases, insertion in a deep sinus, apices 1/3 bifid, sinus narrowly lunate or acute, segments narrowly triangular, ending in piliform acumen, margins unevenly spinose-toothed all around.

Gametangia

Androecia at the end of very short lateral-intercalary branches lacking normal vegetative leaves, arranged in small spikes with up to 4 pairs of bracts, bracts very smaller than the vegetative leaves, imbricated, hemispheric, margins with a few short teeth, bracteoles oblong-rectangular, shortly bifid, margins entire or with rare teeth, slime papillae rare to numerous on the margins and tooth apices of bracts and bracteoles, antheridia stalks biseriate; gynoecia not seen.

COMMENTS

According to Herzog (1953), the type specimen of Chiloscyphus subacuminatus is sterile. The author collected male plants of the species in 2019, which showed the presence of androecia in short spikes on very short lateral branches and allowed the transfer of the species to Heteroscyphus . The transfer is also supported by the underleaves being connate with the nearest leaves on both sides, the subopposite, dorsally connate leaves, and the biseriate antheridial stalks.

Figures

FIG. 19. — Heteroscyphus subacuminatus (Herzog) Thouvenot: A, shoot portion, ventral view; B, C, leaf apices; D, F, half underleaves; E, mid-leaf cells; G, male bract with antheridium; H, leaf. All drawn from Thouvenot NC2740. Scale bars: A, D, F, H, 1 mm; B, C, 500 µm; E, 50 µm; G, 200 µm.

FIG. 20. — Heteroscyphus subacuminatus (Herzog) Thouvenot, comb. nov.: A, shoot in dorso-lateral view; B, antheridium; C, androecia on shoot portion, ventral view; D, shoot portion, dorsal view. All from Thouvenot NC2740. Scale bars: A, C, D, 1 mm; B, 100 µm.