Heteroscyphus etesseanus (Steph.) Thouvenot, 2023

Thouvenot, Louis, 2023, A taxonomic revision of the Lophocoleaceae Vanden Berghen (Marchantiophyta) of New Caledonia, Cryptogamie, Bryologie 20 (1), pp. 1-60 : 26

Heteroscyphus etesseanus (Steph.) Thouvenot , comb. nov.

( Fig. 13 )

Chiloscyphus etesseanus Steph. , Species Hepaticarum 3: 217 ( Stephani 1906).

—

Type: New Caledonia. Etesse s.n. (lecto-, here designated, G [“ex Herb. E. G. Paris, Nova Caledonia, in ditione Noumeana , 1904”, Etesse 12, G00061024 ]!).

FURTHER SPECIMEN EXAMINED. — New Caledonia. North Province, Poindimié, Amoa valley , Tipwadabwé , on rocks in wet mesophilous forest, 163 m, 13.X.2019, Thouvenot NC2752 ( PC [ PC0779851 ]).

DISTRIBUTION IN NEW CALEDONIA. — Hitherto only known from North Province, rarely collected on rocks at low altitude (160-250 m) in wet forest with tall trees. The mention “Nouméa” on the label of the type specimen is not reliable since Etesse’s specimens were not precisely located and were commonly labelled as having originated from the capital of New Caledonia. In fact, his bryophyte gatherings were made along the Tipindjé river in North Province ( Morat 2010), about 30 km from the locality of the recent collection.

TOTAL RANGE. — Endemic to North Province, on the north-eastern versant of the central range.

DESCRIPTION

Dioecious.

Habit

Plants small, wet shoots 1.60 mm wide, stems rigid, leaves horizontally spreading, slightly convex, contiguous, alternate.

Leaves

Rectangular, 0.60 mm long, 0.50 mm wide, apices truncate, concave, both distal angles triangular acute, usually with a short linear tooth three cells long, some leaves pseudo-trilobate, sometimes with a further tooth, apical or subapical on the ventral margin, margins otherwise entire.

Cells

Leaf cells hexagonal, 24-40 µm wide, firm walled without trigone.

Underleaves

Small, hardly wider than the stem, obconical, free on both sides, deeply bifid, the discs sometimes strongly reduced, lobes divergent, setaceous, sinus variable, V-like or lunate or nearly flat, both lateral margins with a single tooth at most, small to linear.

Gametangia

On short leafless, lateral-intercalary branches; gynoecia with laciniate bracts, bifid bracteoles with a single small tooth on both lateral margins; perianths about 1.5 mm hight, campanulate, deeply trilobate, lobes laciniate-toothed, calyptrae very shorter than the perianths; androecia in spikes of up to six pairs of bracts.

COMMENTS

Some vegetative features of the species such as the alternate leaves, the leaf cells without trigones and the small, free underleaves are suggestive of Chiloscyphus . But the spicate androecia on abbreviated ventral branches are typical of the genus Heteroscyphus . Recent studies on Heteroscyphus in Australasia treat species with similar vegetative features and highlight the importance of androecia and perianth types to discriminating these two genera (e.g. Engel & He 2010; Engel 2013, 2015). These studies warrant the transfer of Chiloscyphus etesseanus to Heteroscyphus . Heteroscyphus etesseanus (Steph.) Thouvenot , comb. nov. is superficially similar to H. argutus , but the latter species can be easily distinguished from H. etesseanus (Steph.) Thouvenot , comb. nov. by its larger size and the rounded instead of retuse leaf apices with at least four teeth.

Figures

FIG. 13. — Heteroscyphus etesseanus (Steph.) Thouvenot, comb.nov.: A, shoot portion,ventral view; B-D, leaves; E-I, underleaves;J, median leaf cells; K, tooth at leaf apex; L, androecium; M, female bracteole; N, perianth tearing showing the inserted calyptra; O, female bract; P, perianth. A, L, M-P, drawn from the lectotype of Chiloscyphus etesseanus Steph. (G00061024); B-D, K, from Thouvenot NC2752; E-J, from Thouvenot NC2753. Scale bars: A, L, 1 mm; B-D, M-P, 500 µm; E-I, 200 µm; J, K, 50 µm.