Lejeunea thalassoides M.A.M.Renner & Glenny, 2021

Renner, M. A., de, Lange P. J. & Glenny, D. S., 2021, A synopsis of Aotearoa / New Zealand Lejeunea (Lejeuneaceae: Jungermanniopsida) and new species in the Lejeunea epiphylla Colenso complex, Arctoa 30 (2), pp. 187-212 : 207-210

20. Lejeunea thalassoides M.A.M.Renner & Glenny sp. nov. Figs. 9 , 10 .

Diagnosis: Lejeunea thallassoides is distinguished by its ovate underleaves with a broad U-shaped sinus with obtuse to rounded vertex; the ovate leaf-lobes whose apex is obtuse; the smooth leaf cell surfaces; the lobules with a straight keel, with a first lobule tooth composed of a single-cell or rarely of two or more cells; the dimorphic shoot systems with branches smaller in stature than the primary shoot; gynoecia borne on short lateral branches subtended by a single subfloral innovation that is small-statured and does not continue vegetative growth; and the perianths with a long stipe.

Type: New Zealand, North Island, Hawkes Bay Ecological Region , Heretaunga Ecological District , Tangarewai Stream catchment, Monckton Scenic Reserve , 39° 57.816’S 176° 16.906’E, 290 m, 16.X.2009, M. A. M . Renner 4407 (holotype: AK314727 ) .

Description: Plants forming extensive pure mats lithophytic or terrestrial on limestone and other cation-rich substrates, including cation-rich greywacke and calcareous mudstone. Shoots large for genus, procumbent, sparingly branched, exclusively lateral-intercalary with a basal collar, up to 35 mm long, 1.2–2.5 mm wide. Stems 87–155 µm diameter, with 7 cortical cell rows, but up to 10 in vicinity of leaf insertion lines, and 11–31 medulla cell rows; cortical cell walls evenly and continuously thickened, medulla cell walls unthickened, hyaline. Leaves imbricate, insertion attaining dorsal stem midline, and interlocking across the dorsal cortical cell row, dorsal leaf-free strip absent; lobes ovate-triangular, 348– 1067 (643 ± 135) µm long by 378–1021 (657 ± 123) µm wide, plane or concave along the postical margin, obliquely spreading and weakly dorsally assurgent, postical margin straight or weakly curved from keel to apex, extending away from stem at 45–60° to shoot axis, apex obtuse to acute, antical margin weakly curved then lobe broadly rounded and auriculate to top of stem insertion, lobe medial cells with small triangular trigones, and 1–2 small medial wall thickenings occasionally developed on each wall, lobe cell surface with fine granular ornamentation; lobules approximately one sixteenth the lobe area, 57–304 (184 ± 48) µm long by 56–283 (187 ± 45) µm wide, trapezoid, keel and stem insertion approximately equal lengths, free external margin shorter than free antical margin; carinal region rounded, maximally inflat- ed at keel-stem junction, contoured and rounded outward from this point, inflation weak, carinal region indistinct; keel straight to slightly arched, running cleanly into lobe postical margin; first lobule tooth one or two celled, with cell long axis pointing slightly outward away from shoot apex, single celled tooth with cell fused along its base with one or two cells, usually slightly larger than the tooth cell, and fused along its interior margin with one or two cells for 0.5 to 0.8 of its length; two-celled first lobule teeth usually have cells one atop the other, rarely side by side, the two-celled teeth are hooked inward from their base, but still have their apex pointing outward away from the shoot apex; first lobule tooth separated from second tooth by one or two cells, one of which may be larger than surrounding cells; lobule second tooth indistinct, developed on lobules on robust shoots, broadly rounded, apex with two elongated cells whose long axis is parallel with margin; lobule margin interior of second tooth shallowly curved, marginal cells similar in size and shape to adjacent cells, sometimes down-rolled and obscured in ventral view, but usually visible its entire length. Underleaves contiguous to imbricate, typically obscuring stem and lobules in ventral view, ovate, broadest near base, 201–835 (450 ± 121) µm long by 204–691 (423 ± 96) µm wide, bifid to 0.3, sinus U-shaped, vertex obtuse to rounded, 61–264 (147 ± 45) µm deep, lobes acute, insertion strongly arched, underleaf base slightly cordate, lateral basal cells not inflated. Oil-bodies small, homogeneous, spherical to fusiform, in mature leaves near the shoot apex 16–35 per cell arranged in a submarginal ring. Asexual reproduction absent.

Paroicous. Antheridia on highly abbreviated determinate branches, either produced in pairs from adjacentopposite leaf bases, or scattered, not extending beyond shoot margin, hidden in dorsal view, bearing 2 or 3 pairs of hyaline antheridial bracts, each containing two antheridia, bract stature decreasing dramatically from branch base, sterile bract and underleaf at branch base, underleaves otherwise absent. Gynoecia on short lateral branches, either lacking subfloral innovations, or with one, rarely two Lejeuneoid innovations of reduced stature that grow a short distance before terminating growth. Female bracts united to bracteole on both sides, lobe, lobule, and bracteole more or less equal length, bract lobules lanceolate, sinus between bract lobe and lobule sometimes reflexed. Perianths around 3000 µm long overall, with free perianth c. 2000 µm long, equally pentacarinate, carinae extending around half way down perianth, unfertilized perianths sessile, fertilized perianths with a hyaline basal stipe 900–1010 µm long, of leptodermous cells. Sporophytes not seen.

Distribution and Ecology: Lejeunea thalassoides is endemic to New Zealand, where it occurs in the lower two-thirds of the North Island and throughout the South Island, including in subalpine regions. Lejeunea thalassoides usually grows as a lithophyte or on soil in association with cation rich bedrock such as limestone or calcareous mudstone, but it has been observed as an epiphyll and epimuscicol as well. At Hawkes Bay L. thalassoides was observed forming extensive yellow-green mats of procumbent shoots on calcareous mudstone exposed by a track cutting. At Takaka Hill L. thalssoides overgrew Echinodium hispidum (Hook.f. & Wilson) Jur. on karst under Nothofagus menziesii forest. At Matukituki Valley on the fronds of Polystichum vestitum , again in Nothofagus menziesii forest. In the vicinity of Ootepoti/ Dunedin L. thalassoides appears to be widely distributed and common, as most herbarium specimens came from here, many collected by John Child, at Frazers Gully on shaded rock wall at 100 m elevation; at Peel Forest L. thalassoides was an epiphyll on Austroblechnum lanceolatum (R.Br.) Gasper & V.A.O.Dittrich at the edge of a waterfall; at Flagstaff Hill on an earth bank at stream side in partial shade; at Bethune’s Gully on an earth bank; at Otari in suburban Whanganui-a-Tara/Wellimgton terrestrial on a clay bank in forest; and on the Old Man Range growing amongst Heteroscyphus coalitus alongside a small stream within Nothofagus forest.

Recognition: Lejeunea thalassoides is a distinctive species that, in most instances, should provide little difficulty in identifying. The microhabitat occupied by this species is a good first clue to identity, as the species is almost always associated with cation rich substrates, be they rock or soils derived from them. Not many other Lejeunea species in New Zealand occur as lithophytes or terrestrials on limestone or calcareous mudstone, on which L. thalassoides is found. The combination of characters from the leaf lobe, lobule, and gynoecium will serve to confirm L. thalassoides is at hand. The leaf lobes have a distinct apex, which is often obtuse but may appear acute in the field. The leaf lobe apex shape is best confirmed by dissecting and slide mounting flattened leaves so that their outline is unambiguous. The lobules have a straight keel, are trapeziform in outline and have a first tooth that may be multicellular, often it is composed of two cells sitting side by side, or is a triangular tooth composed of two or three cells. Thirdly, female plants have gynoecia subtended by small-statured subfloral innovations that terminate growth after a few gyres, and do not continue vegetative growth, occasionally gynoecia are not subtended by a subfloral innovation, which is an unusual circumstance within Lejeunea from Australasia.

The long basal stipe on the perianth is shared with L. amphinephea , and the two species are the most likely to be confused with each other in the New Zealand flora, for further guidance on differentiating L. thalassoides from L. amphinephea , particularly when small statured plants expressing a high percentage of explanate lobules are at hand, see the recognition section of L. amphinephea .

Etymology: from the ancient Greek qalassoeid»j, a descriptor of a light sea-green, such as that which occurs in near-shore coastal waters under an overcast sky, in reference to the luminescent green colour of the living plants, and the cation-rich rocks they are associated with.

Conservation: Listed in de Lange et al. (2020) as Lejeunea (a) (WELT H10386; Waitomo). Lejeunea thalassoides is currently known from two localities in the North Island but is more widely distributed in South Island. Often, but not always, L. thalassoides occurs in association with basicolous substrates including basalt and limestone. We suggest that the current listing ( de Lange et al., 2020) of Naturally Uncommon (Range Restricted) is appropriate.

Specimens examined: New Zealand: New Zealand, North Island, Hawkes Bay Ecological Region, Heretaunga Ecological District , Tangarewai Stream catchment, Monckton Scenic Reserve , 39°57.816'S 176° 16.906’E, 290 m, 16.X.2009, M. A. M. Renner 4408 ( AK314735 ); South Island : North West Nelson, Takaka Hill, Harwoods Hole track, 740 m, 30.X.2004, D. Glenny 9235 ( CHR 571826 ); Cass-Canterbury, Woolshed Hill, XI.1960, L. Visch ( CHR 631269 ); Pareora Ecological Region , Orari Ecological District , Peel Forest Scenic Reserve , Rata Falls track, 10.X.2015, D. Glenny 13030b ( CHR 638295 ); Canterbury, Waimate, in forest, V.1901, T. W. N. Beckett, ex herb Levier 2746 (G-19642); Otago, Matukituki Valley near East and West Branches junction, 360 m, 30.XI.2002, D. Glenny 8759 ( CHR 571529 ); Dunedin, Fraser’s Gully, 6 Apr 1973, J. Child ( WELT-H011266 ); Dunedin, base of Flagstaff Hill, 27.X.1949, K. W. Allison H4673 ( CHR 556139 ); Dunedin, Bethune’s Gully, 14.XI.1949, K. W. Allison H4932 ( CHR 556178 ); Dunedin, Fraser’s Gully, 6 Apr 1973, J. Child ( CHR 424338 ); Southland, Bluff-Invercargill-Winton, June-July 1874, S. Berggren ( CHR 263554 ); Old Man Range, I.1961, L. Visch ( CHR 631270 ); Dunedin, Apr 1874, S. Berggren (G-19654) ;

Figures

Fig. 9. Lejeunea thalassoides A: Eight lobules showing variation from fully developed with first lobule tooth of two cells through to few-celled explanate lobules. B: Four underleaves showing variation in size. C: Shoot in ventral view. D: Three lobe apices. E: Dorsal stem surface showing leaf insertion lines that interlock over the dorsal stem midline. F, G: Lobule pair and underleaf comprising single modules, with underleaf partially cut away. H: Three stem transverse sections showing variation in stature. I, J: Underleaf bases showing variation in stem attachment from two to four stem cells. A, B, F, J CHR571529; D, E, G, I, H, WELT-H10386; C, CHR424338.

Fig. 10. Lejeunea thalassoides A: Shoot sector with gynoecia on small stature lateral branches, with or without subfloral innovations. B: Androecia on short lateral branches. C: Two underleaves preceding gynoecia. D: Two sets of gynoecial bracts and bracteole. E: Shoot in ventral view showing production of male and female branches. F: Perianth transverse section. G: Perianth and gynoecium, showing the long stipitate perianth base. H: Nine cladograms showing variation in the production of reproductive structures among shoots. I, J: Two longitudinal sections of perianth base showing free perianth wall above long stipitate perianth base, note also the multiseriate calyptra stalk. A, B, I, H (upper 5) CHR424338; C, D(left) WELT-H10386; E CHR638295; D(right), F, G, H (lower 4), J CHR571529.