Megalembidium insulanum (W.Martin & E.A.Hodgs.) R.M.Schust.
Type: New Zealand, Stewart Is., Pegasus Creek, near waterfall, 9 Jan. 1949, Martin 568 (CHR – absens).
Dendrolembidium martinii Herzog, Ark. Bot. II. 1: 500. f. 12, 13: a–e. 1951.
Type: New Zealand, Stewart Is., Table Hill, 5 Feb. 1947, Martin (CHR – absens).
Key
Distribution and Ecology : Endemic to New Zealand: Stewart Island (3–690 m), South Island (200–860 m). Known from Fiordland, Westland and Western Nelson EPs, the northern limit at Stockton Plateau.
The species typically occurs in scrub or stunted forest where light levels are moderately high, over peaty ground and may form low cushions or mounds, or grow over hummocks formed by mosses and other hepatics. On Stewart Island the species occurs near sea level at the type locality (Port Pegasus, near Belltopper Falls) under Leptospermum scoparium and Dracophyllum longifolium scrub and is common at that locality. At higher elevations on Stewart Island (330–340 m at Pryse Peak) it forms pure, deep cushions in an open forest that includes stunted Dacrydium cupressinum, Podocarpus hallii, Olearia colensoi, Gahnia, Blechnum and bryophyte cushions on the forest floor. It reaches its upper altitudinal limit at 600–690 m at the Mt. Rakeahua summit area, occurring in mosaic communities of penalpine cushion vegetation, herbfields, Chionochloa, prostrate Leptospermum scoparium, Olearia colensoi from 0.5 m to 2 m tall and significant areas of exposed rock; at this site the species formed a large mound with Riccardia sp. and Eotrichocolea admixed.
In Fiordland, it is recorded from Doubtful Sound Track at 455–490 m with Treubia lacunosa, Haplomitrium gibbsiae, Lembidium nutans, Pseudocephalozia lepidozioides, Lepidozia spp. and Riccardia spp. (Schuster, 1980a). At Omoeroa Saddle (Westland Natl. Park, 330 m) the species occurs in a bog with shrub heath vegetation that includes Juncus, Carex and stunted Libocedrus bidwillii surrounded by mature Dacrydium cupressinum forest. At this site it is found on the bog floor or, at times, on low-lying mounds. It also occurs at 860 m in the Alexander Ra. At Sewell Peak it occurs in extensive hummocks under stunted Nothofagus solandri var. cliffortioides and Halocarpus biformis forest near treeline, with Bazzania adnexa, Breutelia pendula, Dicranoloma billardierei, D. robustum, Heteroscyphus billardierei, Hymenophyllum multifidum, Hypnodendron colensoi, Lepidozia kirkii, Luzuriaga parviflora and Riccardia cochleata.
The generic description serves to characterize the single species.
Comments : Megalembidium may easily be mistaken for Isolembidium and to a lesser extent Kurzia tenax, both of which occur in New Zealand. The three genera are similar in plant organization, with a basal, prostrate, branched, stoloniferous, leafless system from which arises an erect, dendroid, 2–3-pinnate, photosynthetic system ± determinate in height, the stem and its branches resembling a “megaphyll.” Moreover, in all three the erect photosynthetic system is comprised of terminal branches of both Frullania and Microlepidozia types (see Fig. 118: 1 [Megalembidium] and Fig. 111: 1 [Isolembidium]). The three species may be distinguished by the following key:
Megalembidium is placed in subfamilyLepidozioideae by Schuster (1979a, 1980c, 1984e, 2000a). However, Engel and Braggins (2005) demonstrated that the genus should be removed from the Lepidozioideae and placed in an independent subfamily. Engel and Braggins (2005) also discussed the similarities of Megalembidium to Isolembidium of subg. Lembidioideae. A remarkable characteristic of the sporophytes of Megalembidium is the spiral dehiscence of the capsule wall (Fig. 118: 2, 3). Spiral capsule dehiscence also occurs in most members of the suborder Balantiopsidinae (sensu Schuster, 1973; see also Engel and Merrill, 1997), some Calypogeiaceae, in Geocalycaceae (Saccogynidium) and in Plagiochilaceae (Plagiochila gigantea).
