Psiloclada clandestina Mitt.
Psiloclada clandestina subsp. clandestina fo. major R.M.Schust., J. Hattori Bot. Lab. 48: 411. 1980, syn. nov.
Psiloclada major (R.M.Schust.) J.J.Engel, Phytologia 58: 324. 1985.
Type: New Zealand, South Is., Westland Prov., Haast Pass, Schuster 59641.
Plants filamentous and thread-like in smaller phases to leafy in aspect in vigorous phases, with wiry, rigid, brittle axes; shoots to 345 µm wide with leaves. Branches remote and irregularly pinnate to frequent, distinctly and regularly 1(2)-pinnate, the terminal branches frequently becoming flagelliform; branch half-leaf 4(5)-lobed; first branch underleaf 2–3-lobed. Rhizoids rare, lacking in distal shoot sectors. Leaves rigid, firmly attached, 120–175 µm wide × 100–175 µm long, on main stems (5)6–9(10)-lobed, moderately asymmetrical, the ventral 1–2 lobes larger, formed of 2–3 to 4–5 cells, the dorsal smaller, usually 1(2)-celled. Lobes each ending in a highly differentiated, erect, unicellular, conspicuously elongated, hyaline, rigid, setose apical cell, the apical lobe cell directed toward stem apex or inclined toward stem, basally often a little dilated and bulb-like, long-tapered, 10–12 × 84–110 µm. Disc asymmetrical, 2 cells high in dorsal half, to 4–5 cells high in ventral half, the disc 10–16 cells wide at base. Cells of disc and lobe bases thick-walled, small, the median disc cells 12–17 × 15–19 µm. Oil-bodies absent, but a few droplets present in some disc cells, when present, obscure, 1–2(3) per cell, hyaline, homogeneous or consisting of a few obscure inconspicuous spherules, much smaller than chloroplasts. Oil-droplets of stem cortex cells 0–5(7) per cell, homogeneous, colorless, 0.75–1.5 µm in diam., ellipsoidal or spherical or an irregular variant on spherical. Chloroplasts very large for cell size, in disc and all lobe cells except the long curved tip cell, which is devoid of contents. Underleaves of main stems (3)4–6(8)-lobed, the lobes usually consisting of a basal cell and a setose apical cell; disc rudimentary, spreading, 2 cells high. Fungal partner an ascomycete.
Androecia on abbreviated, tightly spicate branches from leading shoots; bracts ventricose, the lobes acuminate, terminating in a uniseriate row of 2–3 cells, the terminal cell very long and narrowing toward the tip, the lobe bases crenate-denticulate; margins of disc sparingly crenate-dentate, devoid of slime papillae. Gynoecia with bracts of innermost series much larger than leaves, erect and closely ensheathing the perianth but often with diverging lobes, the bracts concave, bifid; lobes caudate, the tip consisting of a uniseriate row of 2–3 very elongate cells, the lobe margins crenate-denticulate often by the variously projecting distal end of lobe cells; lamina composed of irregularly short- to long-rectangular, leptodermous cells, the margins sparingly crenate-dentate; bracteole similar in size and form. Perianth rather inconspicuous in situ yet rather large for plant size, straight to curved; mouth with cilia each consisting of a single elongate cell or a uniseriate row of 2 elongate cells (ca. 9–12 × 120–150 µm), the distal end of the penultimate cells often projecting and forming a shoulder-like process.
Capsule wall 2(very locally 3)-stratose, 16–20 µm thick, the outer layer 1.4–1.6× thicker than inner layer; outer layer of cells feebly tiered, ca. 28–34 × 45–48 µm, ± regularly short-rectangular, the alternating walls with thin, sheet-like thickenings and feebly nodule-like swellings lending the vertical walls a sinuous appearance, the transverse walls devoid of thickenings; innermost layer of cells longer and narrower, 8–12 × 45–75 µm, mostly with nodule-like to spine-like thickenings, with complete semiannular bands sporadic and often non-pigmented in median sector.
Spores 12.5–13.9 µm in diam., with a network of low, often furcate ridges that often anastomose to form irregular and weak areolae. Elaters 8.2–8.6 µm wide, feebly to moderately tortuous, only slightly tapering toward tips, bispiral to tips, the spirals 2.9–3.4 µm wide.
Distribution and Ecology : New Zealand: Auckland Islands, Stewart Island, South Island (0–660 m), North Island (200–580 m), Chatham Islands; Australia: Tasmania, Victoria. In New Zealand known from Fiordland, Westland, Western Nelson, Marlborough, Southern North Island, Volcanic Plateau (Lake Rotoehu), Taranaki (Mt. Taranaki), Auckland (Mt. Moehau) and Northland (Waipoua Forest) EPs. Very common in lowland forests of Westland and Fiordland, but the comparatively few collections from the North Island suggest it is relatively uncommon there.
In pure mats or woven through other bryophytes, on rotting wood and tree roots, humic soil, occasionally seen hanging in wefts from soil and other bryophytes, occasionally on rock surfaces. In the North Island usually on or at base of tree-fern trunks (with Calomnion complanatum, Bazzania tayloriana and Trichomanes venosum); rarely epiphyllic (on Hymenophyllum ferrugineum). Found under lowland to montane forest, mainly under lowland forests of Dacrydium cupressinum, Weinmannia racemosa, Quintinia serrata, Metrosideros umbellata, under Nothofagus solandri and N. menziesii forest, or under Lepidothamnus intermedius forest. Found most constantly in association with Bazzania nitida, Zoopsis argentea and Rhizogonium pennatum. Other species that sometimes occur with Psiloclada are Acrobolbus lophocoleoides, Acromastigum anisostomum, A. colensoanum, A. marginatum, Bazzania hochstetteri, B. monilinervis, B. novae-zelandiae, Clandarium xiphophyllum, Distichophyllum pulchellum, Ditrichum punctulatum, Heteroscyphus billardierei, H. decipiens, Kurzia hippuroides, Lembidium longifolium, Lepicolea scolopendra, Lepidozia kirkii, L. concinna, L. spinosissima, Leucobryum candidum, Marsupidium knightii, Podomitrium phyllanthus, Rhizogonium distichum, Riccardia cochleata, R. crassa, Saccogynidium australe, S. decurvum, Schistochila glaucescens, S. nobilis, Telaranea tuberifera, Trichomanes venosum, Trichotemnoma corrugatum, Tylimanthus diversifolius, Zoopsidella caledonica, Zoopsis bicruris, Z. ceratophylla, Z. leitgebiana, Z. matawaia and Z. setulosa.
Comments : Psiloclada clandestina is here defined to include plants that are variable in vigor, leaf lobe number and underleaf lobe number. Smaller phases are filamentous in aspect and have 5–6 leaf lobes and 3–4 underleaf lobes. This is the phase regarded as P. clandestina fo. clandestina in Schuster (1980a) and P. clandestina s. str. in Engel (1985). Subsequent detailed studies of New Zealand populations have revealed that a single species occurs within here and that an increase in vigor is coupled with an increase in the number of leaf and underleaf lobes. Particularly vigorous plants have leaves 8–9 to even 10-lobed and underleaves 5–6(8)-lobed; such plants are often leafy in aspect. This phase was recognized taxonomically as P. clandestina subsp. clandestina fo. major in Schuster (1980a) and as a distinct species, P. major, in Engel (1985).
In the field, Psiloclada clandestina may be recognized by the minute size, the very slender, wiry plants with tiny and mostly remote leaves with lobes stiffly oriented toward the shoot apex and by the dull olive-green or brownish green color.
