Zoopsis nitida Glenny, Braggins & R.M.Schust.
Zoopsis nitida Glenny, Braggins & R.M.Schust., J. Bryol. 19: 776. f. 1. 1997.
Holotype: New Zealand, North Auckland, Waipoua Forest, Lookout track, 100 m, Glenny 5474 (WELT); isotype: (CHR).
Plants vermiform, creeping, pure green, highly nitid, to 550 µm wide. Branching sparing, the branches sporadically furcate, of Frullania type; ventral-intercalary branches common, frequently stoloniform. Axes flat or somewhat convex dorsally, rounded into the margins, the dorsal cortical cells in 2 rows, the cells prominent, convex, their inner margins forming a zigzag median line; lateral margins of axis on each side comprised of a row of inflated cells considerably smaller than those of the dorsal cortical cells; ventral surface comprised of 2 narrow, elongate cells (= ventral merophytes), these flanked on each side by (1)2(3) rows of larger subisodiametric cells; medulla of 9–12 rows of small, strongly elongated cells forming a well-defined central strand. Rhizoids few, short, at bases of underleaf vestiges and at lateral leaf bases, the apices sometimes dilated and/or incipiently lobed. Leaves rudimentary and ephemeral, visible only at shoot apex, usually a mere thin-walled, spur-like, hyaline solitary cell inserted laterally on one of the lateral (superficially dorsal) cells (the collapsed remnants of these visible at times on mature axis margins); the “leaf” usually elongate or acuminate and pointed, sometimes turned toward the axis apex, its anterior margin at times with a delicate, soon-collapsed hyaline papilla; leaf rudiments rarely 2–3-celled, then formed of vestigial lobes, each of 1–2 cells. Oil-bodies (Schuster, 1999a) finely granular or granular-botryoidal, smaller and fewer in dorsal cortical cells, ca. (3–4)5–16 per cell; ventral surface of axis with more numerous and larger oil-bodies, the lower lateral cortical cells adjoining the ventral cortical cells with ca. 14–25 oil-bodies per cell; oil-bodies in the elongated ventral cortical cells ca. 15–30, crowded, only marginally smaller than those of adjoining cells. Underleaves rudimentary and ephemeral, near shoot apices consisting of 2 subquadrate to subglobose cells (“disc”) from which rhizoids originate and 2 short-cylindrical 1-celled “lobes,” the lobe cells each terminating in an ephemeral, minute, hyaline papilla. Asexual reproduction lacking.
Androecia at apices of abbreviated, weak, ventral-intercalary branches; bracts few-celled, bilobed; antheridia 1 per bract, the stalk uniseriate. Gynoecia on feeble, ventral-intercalary branches; bracts oblong-ovate, 3-lobed, but often with a third smaller lobe or tooth; lobes acute, 2–5 cells wide at base, terminating in a uniseriate row of 2–3(4) cells. Perianth urceolate to obpyriform, wide at the mouth, deeply divided into 6 slender lobes, the lobes 2 cells wide near base, terminating in a uniseriate row of 2–3 progressively smaller cells.
Seta with 8 rows of outer cells surrounding an inner core of 12–13 rows of small cells. Capsule not seen.
Spores 15 µm in diam., delicately reticulate, the ridges low. Elaters bispiral, the spirals delicate.
Distribution and Ecology : Endemic to New Zealand: South Island (100–200 m), North Island (240–680 m). Known from Westland (Lake Matheson, Mt. Te Kinga, Bullock Creek) and Northland (Waipoua Forest, Tutamoe Ra.) EPs.
The species occurs in lowland forest among tree roots, in tree root caves on humus, on the lower side of a rotten tree trunk and on the base of the caudex of Cyathea dealbata, in humid, usually rather shaded situations (but not in so consistently strongly shaded habitat as Zoopsis bicruris). It occurs in various lowland forests: tall podocarp forest mostly comprising Dacrydium cupressinum (Lake Matheson, S Westland, 100–200 m), Weinmannia racemosa – Quintinia serrata – Metrosideros umbellata forest (Mt. Te Kinga, 400 m), Agathis australis – Metrosideros robusta forest with a Cyathea dealbata understory (at the type locality) and Weinmannia silvicola – Melicytus ramiflorus forest with an understory of Cyathea smithii, Ripogonum scandens and Freycinetia baueriana (Tutamoe Ra., Northland, 480 m). Accompanying species are Bazzania adnexa, Calomnion complanatum, Kurzia hippuroides, Leucobryum candidum, Mittenia plumula, Psiloclada clandestina, Saccogynidium australe, Schistochila appendiculata, Sticta filix, Telaranea herzogii, Zoopsis argentea, Z. bicruris, Z. ceratophylla and Z. setulosa.
Comments : Zoopsis nitida has the most reduced leaves of any species in the genus. The 1-celled rudimentary leaves with a hyaline papillae are present at the shoot apex but collapse as the shoot matures.
The species is most likely to be confused with the rudimentary-leaved Zoopsis bicruris. In the field, the two can be separated by the shape of the apex, uniformly tapering in Z. nitida whereas Z. bicruris has a clavate apex that narrows suddenly to the tip; Z. nitida has 4 rows of cells visible on the dorsal stem surface while Z. bicruris only has two. Terminal branches will confirm the presence of Z. nitida. Under the dissecting microscope the leaves are difficult to see in both species, but the difference in the number of dorsal stem cell rows easily differentiates them and is the easiest way to identify dried specimens. In Westland the two may be found growing together.
Schuster (1999a, p. 53) remarks that this species is “... one of the most distinctive of all hepatics” and it takes the trend toward the thallose condition further than any other Zoopsis species.
