Diplophyllum novum J.J.Engel & G.L.Merr.
Diplophyllum novum J.J.Engel & Merrill, J. Hattori Bot. Lab. 84: 274. f. 8. 1998.
Holotype: New Zealand, South Is., Otago Prov., unnamed peak immediately NE of Mt. Cargill, N of Dunedin, ca. 550 m, Engel 17589 (F); isotype: (CHR).
Plants rather rigid, prostrate to loosely creeping, rather dull, light green, without reddish pigmentation in sterile portions (perianths sometimes castaneous); shoots medium, to 1.8 mm wide. Branches rather frequent, lateral-intercalary. Rhizoids scattered on ventral face of stem, often dense. Leaves rigid, contiguous to imbricate, conduplicate-bilobed, the dorsal lobe not appressed to the ventral but slightly elevated, the leaves somewhat dorsally assurgent when dry, when moist horizontal to slightly and broadly decurved, spreading at 90° to stem, not falcate, the keel 0.25(0.3) the leaf length, strongly arched, the sinus abruptly reflexed and often flaring, the opposing dorsal lobes (even when ventral lobes imbricate) not overlapping, not extending beyond the stem midline. Ventral lobe plane or the apex decurved, the insertion obliquely succubous, recurved at ventral end, or the ventral margin of lobe cordate to truncate at base and free, not decurrent, the lobe rather narrowly oblong to elliptic, distinctly lingulate, abruptly contracted at the keel; apex broadly rounded to subtruncate or sporadically bluntly acute, finely denticulate to subentire, rarely with a sharp 1(2)-celled apiculus; ventral margin rather straight to weakly arched, finely and regularly to somewhat irregularly denticulate to subentire, often ± repand. Dorsal lobe plane, asymmetrically ovate to short-elliptic, 0.5–0.6 the length of the ventral, 0.25–0.35 the area of the ventral lobe, the insertion ± transverse, not decurrent, the apex broadly rounded to subacute, rarely with a minute single-celled sharp apiculus; dorsal margin weakly arched, the margins with denticulation similar to that of ventral lobe, the teeth of dorsal base not differentiated, the margin ± straight and not contracted at the base. Marginal teeth unicellular, consisting of conical or papilla-like projections of the exposed marginal cell walls, the teeth at the ventral base spinulose, ± straight and sharply tapering, to 3:1. Cells of median portion of ventral lobe short-rectangular, 12–15 µm wide × 19–26 µm long (ca. 2:1 or a little more); subapical and marginal cells ± isodiametric, subquadrate, the walls slightly thickened, with minute trigones, 9–10 µm wide × 11–13 µm long, the median field of short-elongate cells extending into the distal half of the lobe, the lobe thus appearing subvittate, the subapical cells in ± regular arching tiers; marginal row of cells at times with anticlinal divisions, forming an indistinctly differentiated border; median basal cells of ventral lobe larger than the median cells, thin-walled, with minute trigones, 14–16 µm wide × (28)37–40(47) µm long (to ca. 2.5:1); dorsal lobe with a field of short-elongate, large cells extending laterally from keel to ca. 0.5 lobe width and distally to middle of lobe or a little less than keel length; surface coarsely papillose, the papillae rounded, 2–4(5) per cell in distal and marginal cells; elongate cells of median base finely striate-papillose. Gemmae common, 1-celled, pale green, 11–12 µm in diam., polygonal, with several blunt projections; gemmiparous leaves erose-margined, often with the apex of ventral (and sometimes dorsal) lobe(s) abruptly contracted to a broad, ragged mucro formed of elongate-rectangular cells, the gemmae produced along its margins.
Monoecious, with both paroecious inflorescences and with androecia on lateral-intercalary branches some distance below gynoecia, the androecia subfoliose, the bracts in 2–3 pairs, similar to leaves in shape and form except the dorsal lobe somewhat ventricose toward base and often narrowly reflexed at apex; antheridia 2 per bract, the stalk uniseriate. Subgynoecial leaves gradually increasing in size toward perianth, the dorsal lobe plane or at times ± inflated (these rarely with an antheridium), the bracts of innermost series largest, leaf-like except the dorsal lobe larger and ca. 0.5 the ventral (not smaller, deeply concave, and shallowly 2– 3-lobed as in Diplophyllum dioicum). Perianth clavate, plicate in distal 0.35(0.5), contracted to mouth, shallowly lobulate distally, the lobules spinose-dentate, the larger teeth with a uniseriate row of 2–3 somewhat elongated cells, intermixed with several 1-celled teeth; cells in region of mouth thin-walled, those of perianth proper distinctly thick-walled and with a rounded lumen.
Capsule short and broadly ellipsoidal, the wall 3(locally 4)-stratose, 28–36 µm thick, the outer layer equal in thickness to the 2 inner layers or a little less; outer layer of cells short-rectangular, with indistinct two-phase development, the longitudinal walls with rather thin, pigmented sheet-like thickenings and well-developed peg- to spur-like thickenings, 4–5 per longitudinal wall, the alternating walls with similar thickenings, but weaker and not or less strongly pigmented, the transverse walls without or with sporadic nodular thickenings; innermost layer of cells elongate-rectangular, the radial walls with nodular to spur-like thickenings, the thickenings often extending onto outer tangential wall as complete, narrow semiannular bands (especially in distal half of valve).
Spores 8.6–9.6 µm in diam., with distinct, sharply defined, broad, sinuous vermiculate markings. Elaters tortuous, 6.7–7.7 µm wide, bispiral to the tips.
Distribution and Ecology : Endemic to New Zealand: South Island (550–800 m). Known from only three sites in Fiordland (Lake McKerrow track), Otago (Mt. Cargill) and Canterbury (Governors Bush) EPs. Occurring in a rock crevice (type) and on a shaded, moist cliff face in a Nothofagus menziesii forest (Governors Bush, Mt. Cook Natl. Park, Canterbury). It has been found growing with Andreaea acuminata, Cryptochila grandiflora and Ditrichum punctulatum.
Comments : Diplophyllum novum is monoecious, but in addition to paroecious inflorescences, androecia are produced on lateral-intercalary branches some distance below the terminal inflorescence on leading shoots (Fig. 168: 1). This species differs from D. domesticum in the broadly rounded to subtruncate lobe apices (Fig. 168: 1, 2, 4, 7); the oblique (ventral half) leaf insertion (Fig. 168: 3); the variable monoecious condition (vs. strictly paroecious in D. domesticum); the less strongly armed leaf margins, at times being subentire; and the larger plant size, up to 1.8 mm wide (vs. 1.4 mm wide or less in D. domesticum).
The bracts subtending the gynoecia are sometimes inflated at the base, but after a careful examination of numerous shoots these were nearly always empty. In only two instances a single shriveled antheridium was found in the axil of a bract, whereas the antheridia of the androecia on lateral branches of shoots bearing mature sporophytes had not yet dehisced (Fig. 168: 1, ♂). This suggests that the species may be normally protogynous, with males produced subsequently on lateral-intercalary branches, but can also be protandrous, as in Diplophyllum domesticum, with the males preceding the females on the main shoot.
Diplophyllum novum and D. incrassatum differ from other Australasian Diplophyllum species in the oblique insertion of the ventral half of the leaf (D. novum, Fig. 168: 3), the others being ± transverse throughout. The broadly rounded to subtruncate ventral lobe apices and finely denticulate margins of D. novum are reminiscent of D. dioicum, but the areolation of the leaves is more like that of D. domesticum, with a rather broad median field of rectangular cells extending to the middle of the ventral lobe and beyond (Fig. 168: 4, 5). In D. dioicum the cells of the distal half of the leaf are uniformly isodiametric, and there is a ± sharply delimited vitta of elongate cells with pitted, sinuous walls, which scarcely exceeds the keel in length.
This species is probably normally green, although perianths in the type are reddish brown pigmented. Assuming that pigmentation is habitat-induced, it is noteworthy that the type is intermixed with plants of Balantiopsis diplophylla var. hockenii that are distinctly reddish tinged.
