Nowellia asperilobula Thouvenot, 2021

Thouvenot, Louis, 2021, A new species of Nowellia Mitt. (Marchantiophyta, Cephaloziaceae) discovered in New Caledonia, Cryptogamie, Bryologie 20 (10), pp. 149-153 : 150-153

Nowellia asperilobula Thouvenot , sp. nov.

( Figs. 1 , 2 )

DIAGNOSIS. — Similar in size and overall aspect to Nowellia pusilla , but differing from it by the entire-margined leaves without any tooth-like or ciliate appendage, leaf lobes made of a single row of elongate cells from base to apex, and leaf lamina conduplicate with an ovoid, fully inflated lobule and a rounded keel typically ornamented by strongly protruding mammillose cells, the mammillae rounded to conical in shape.

TYPE. — New Caledonia. South Province, Yaté, Wé Toa, on dead wood in a low wet forest on ultramafic bedrock, interwoven in a mat of various liverwort species, 500 m a.s.l., 166°57’5”E, 22°13’10”S, 8.IX.2019, Thouvenot NC2953 (holo-, PC [ PC 0712112], isotype in the author’s private herbarium)

DISTRIBUTION. — New Caledonia; only known from the type collection in South Province (Yaté).

HABITAT. — This tiny species is easily overlooked and its ecology and distribution therefore remain little known. The type specimen was collected in a low rainforest characterized by small trees, to 5 m high, with thin trunks when growing on ridge or steep slopes, the trunks becoming larger when growing on flat or hollow spaces. Bryophytes occur mostly near the ground on dead wood, stumps and lower part of trunks, less than 2 m above ground level. Nowellia asperilobula sp. nov. was growing on dead wood, with tiny shoots creeping intermixed among the more robust liverworts Acromastigum adaptatum Hürl. , Neolepidozia heterotexta (Steph.) E.D.Cooper , Chiloscyphus heteromorphus (Steph.) J.J.Engel & R.M.Schust. , Tricholepidozia chaetocarpa (Pearson) E.D.Cooper and Zoopsis liukiuensis Horik. The rainforest where the species was found occurs near the ridge of the low coastal ranges in the ultramafic southern massif of New Caledonia. These forests stand like islands of moisture within large, drier shrubland areas. Nowellia asperilobula sp. nov. is the second endemic species recently described from this locality, together with Pycnolejeunea apiculata Thouvenot & Gradst. ( Thouvenot & Gradstein 2021).

DESCRIPTION

Dioicous

Habit

Plants light green to almost hyaline, often with red pigmentation, shoots creeping on the substrate or on larger liverworts, remotely branched, branches ventral-intercalary, similar to the main shoots, rhizoids scattered on ventral side, hyaline, smooth, ending in shortly branched tips.

Stems

Translucent stems 62-75 µm thick, cortical cells short rectangular, 35-45 µm long, 25-35 µm wide, in transverse section, seven cortical cells wider than the three medullar ones, external walls slightly thicker than internal ones, firm to thin, without or with small angular thickenings.

Leaves

Distant, alternate, succubous, narrowly inserted, 4(-5) cells at the insertion on the stem, dorsally secund, inflated lobules conspicuous on both lateral sides of the shoots, curved thread-like lobes dorsally exserted; leaves 250-400 µm long, 150-180 µm wide, bifid to half-length or more, the entire basal part inflated, (80-)100(-130) µm long, 150-180 µm wide when fully developed, conduplicate with a saccate dorsal lobule; lamina 4(-5) cells high, ventral margin nearly straight, entire, 3 cells long, sinus rounded and ± plane, (2-)3(-4) cells wide, laminal cells quadrate to rectangular, 12-25(-37) µm long, 10-15 µm wide, thin-walled, walls slightly sinuous; keel rounded, typically with some strongly mammillose cells, the mammillae rounded to conical in shape, but mammillae in some or many leaves low or absent; lobule ovoid, strongly and fully inflated, almost as large as the lamina, the lobule apex usually ending 1-2 cells below the sinus of the lamina, lobule free margin entire, not flattened against the lamina, the lobule apex narrow, 2(-3) cells wide, incurved, forming an obtuse to rounded tooth, lobule cells long rectangular, the median usually 37 µm long, 12 µm wide; leaf lobes filiform from base to apex, made up of a single row of (5-)6(-7) elongate cells, the lobe sometimes gradually narrowed to the tip or little, lobe cells thick-walled, somewhat thickened at the angles, 30-40 µm long, basal cells 20-27 µm wide, median cells 12-15 µm wide, dorsal lobe erect to typically patent and curved in the lower half, ventral lobe erect and nearly straight to curved, rarely 2-celled at the base.

Underleaves

Lacking.

Asexual reproduction

1-celled rounded gemmae produced on vestigial leaves made up of a flat, 2-3 cells wide lamina and two very short, 1-2 cells long lobes.

Androecia

Terminal on leading shoots or short ventral-intercalary branches, with frequent acroscopic innovations bearing normal or gemmiferous leaves; 3-9 pairs of male bracts, the bracts dorsally assurgent, oval, concave, 300 µm long, ⅓ bifid, apex incurved, sparsely toothed, ventral lobe acuminate in a linear apex 2(-3) cells long, ventral margin entire or with a small, rounded tooth below the lobe base, dorsal lobe smaller, angular tooth linear 1-2 cells long, dorsal margin crenulate or denticulate.

Gynoecia

Not seen.

Figures

FIG. 1. — Nowellia aperilobula Thouvenot, sp. nov.: A, vegetative shoots, habit; B, vegetative shoot, lateral view; C, male shoot; D, male shoot with acroscopic innovation Abbreviations: ms, main shoot; vb, vegetative branch; and, male branch with androecium; and, androecium; n, new vegetative shoot. All from the holotype. Scale bars: A, 500 µm; B, 200 µm; C, D, 500 µm.

FIG. 2. — Nowellia asperilobula Thouvenot, sp. nov.: A, B, leaf shapes with marginal cells shown; C, leaf, dorsal view; D, mammillose cells of the keel in profile view; E, F, leaf lobes; G, vestigial leaf; H, I, keel in profile view with basal cells of dorsal lobe shown; J, lobule cells, dorsal view; K, lamina cells, ventral view; L, stem transverse section; M, male bract flattened (dorsal lobe margin folded over); N, male bracts in situ, dorsal view; O, gemmiferous leaf. All drawn from the holotype. Scale bars: A-C, 100 µm; D, H-I, 50 µm; E-G, J-L, O, 20 µm; M-N, 50 µm.