Lejeunea hodgsoniana, a newly described, long recognised Lejeunea (Jungermanniopsida, Lejeuneaceae) from lowland coastal forest habitats in New Zealand

Abstract Lejeunea hodgsoniana Grolle ex R.J.Lewington, P.Beveridge & M.A.M.Renner sp. nov., A taxon originally recognised by Riclef Grolle in 1980, but not described, known from a number of coastal sites in the North Island, the northern extremity of the South Island, the Kermadec Islands, and the Chatham Islands of New Zealand, is described and illustrated. The species is distinctive amongst species of Lejeunea in the Australasian flora in the combination of complanate shoots, relatively large broadly-ovate leaf lobes, with some lobules bearing prominent multicellular triangular teeth on a base of two to four cells, the flattened perianths having a faint dorsal carina. Its publication brings the number of species recognized for New Zealand to 14, seven of which are currently considered endemic.


Introduction
Th e Museum of New Zealand Te Papa Tongarewa herbarium (WELT) holds fi ve Lejeunea specimens bearing determinavit slips signed by the late Riclef Grolle, dated 1980 and carrying the name Lejeunea hodgsoniana. Th e specimens had been collected in 1969-1970 by B.G. Hamlin, botanist and curator of the herbarium, at that time in combined with complanate shoots, distant elliptic-ovate underleaves with deep sinus and narrow lobes that are usually capped by a single pointed apical cell, and an obcordate perianth with a broad fl attened dorsal surface before infl ation, and reduced dorsal carina.
Plants bright green, not pellucid, grey-green in herbaria, forming conspicuous more or less circular mats to 7.0 cm diameter, or more extensive mats by confl uent growth. (Figure 3) Shoots 1.0-1.5 mm wide, ca. 12 mm long. Branching of the Lejeunea -type frequent, shoots occasionally exhibiting more or less pinnate growth patterns but more often forming diff use complanate wefts by continued lejeuneoid branching.
Stem ( Figures 1G and 2D) 90-125 μm in diameter with 7 cortical cells, walls 2-3 μm thick, and with ca.12 rows of smaller medullary cells. Ventral merophyte of two rows with cells sub-quadrate to rectangular, 22-45 μm × 22-30μm. Lateral merophytes with shared mid-dorsal row, the alternate contribution of each lateral merophyte to the row, 5-6 (8) cells long, with cells quadrate to rectangular, 22-45 μm × 17-24 μm, the contribution boundaries marked by oblique cross walls, by the antical lobe insertion of the contributing merophyte encroaching weakly onto the mid-dorsal row and by the position of a papilla.
Lobules (Figure 1 A-E) polymorphic and relatively small, 0.023-0.125 of lobe area, best developed towards the apex of leading shoots, there 90-240 μm at insertion with a 100-300 μm carina, the free margin weakly infl ated, in-rolled or not, arcuate or more or less straight, bearing a multicellular sub-triangular apical tooth, two to four cells wide at the base, up to 15 cells in total, arched or straight, usually pointing towards the stem apex. Lobule papilla proximal to the tooth and a further papilla at the free margin-stem axil. More distant from the shoot apex the lobules are explanate, the tooth diminishing to three cells on a base of two cells, to two uniseriate cells, or to a single cell. Amongst and postical to the gametangia, the lobules are usually more uniformly small explanate triangular, insertion ca. 50 μm, with a single-celled tooth, carina ca. 50 μm.
Underleaves ( Figures 1F and 2A) usually distant, contiguous or imbricate only at the stem apex, appressed to stem, elliptic-ovate, widest below mid leaf, in leading shoots 320-350 μm long × 260-300 μm wide, smaller to 200 × 170 μm in branch shoots, sinus 0.5-0.6, narrow U or occasionally V-shaped. Attachment transverse, occasionally to two, typically to three cortical cells. Where three, to the lateral merophyte row bearing the adjacent lobule, as well as to the two ventral merophyte rows, with or without a pair of enlarged basal marginal cells. Lobes 6-9 cells wide at base, usually ending in a single cell, occasionally two uniseriate, very occasionally two cells juxtaposed.
Asexual propagules not seen. Autoicous. Androecia ( Figure 1F and 2B) ca. 500 μm long × 500 μm wide, usually on short determinate achlorophyllose lateral branches, often obscured from above by the shoot leaves, occasionally terminal on short leafy lateral shoots. One (2) proximal underleaves often connate on one side with a proximal small sterile bract. Fertile male bracts 2-4 pairs, becoming smaller distally, each bearing one or two spherical antheridia, each ca.100 μm diameter, supported by a fi lament of uniseriate cells.
Gynoecia ( Figure 1H-J) occasionally terminal on leading shoots, subtending a single subfl oral lejeuneoid innovation to continue shoot growth, more often terminal on lateral branches which may be repeated in continued lejeuneoid shoot sequences.
Perianths ( Figure 1H and I) before distortion by enlargement of the sporophyte, dorso-ventrally compressed, pentacarinate, with well-developed lateral and ventral carinae and a reduced dorsal carina. Perianth obcordate in profi le, broadest below the broadly rounded apices of the lateral carinae, 500-750 μm high by ca. 80 μm wide at the base, ca. 500 μm wide at the apex, the ventral carinae before infl ation as two conspicuous oblique plicae converging on the plane ventral surface below the rostrum, a short dorsal carina ca. 88 μm long as an obscure low-profi le ridge immediately below the rostrum on the broad plane dorsal perianth surface, sometimes wanting. Rostrum 45 μm wide, 37.5-50 μm, two to three cells high, positioned in a variably-expressed depression between spreading apices of the lateral carinae. Estipitate.
Cells of the valve outer layer diff erentiated into three distinct areas. Firstly, in the apical part of the valve, a marginal layer of quadrate to rectangular cells with fi rm walls, some with a single nodular thickening on median walls or broader sheet thickening, joined by a single row of rhomboidal cells with similar thickening to a conspicuous median cluster of about 12 large, relatively thin-walled elongate-hexagonal cells without wall thickening, the largest four, ca. 62.5 × 32.5 μm. Secondly, a median basal cluster of thin-walled quadrate cells. Th irdly above the junction of adjacent valves on each side, small quadrate marginal cells with conspicuous sheet thickening on the medial walls bordering a cluster of three to four rows of rhomboidal cells with sheet and nodular thickening and variably sinuose walls. Below the valve junction a row of four large quadrate-trapezoid cells extending to the hypophysis basal cell, together with the row of the adjacent valve, forming a conspicuous triangular group.
Cells of the capsule inner layer quadrate at the apex margin, otherwise rhomboidal, longer than outer layer cells with rounded ends, elliptical near valve junction, quadrate at the base.
Inner layer inner tangential walls with hyaline to light brown ornamentation in two valve regions. At the valve apex, bell and discoid thickening present at the points of attachment of the elaters and weakly extending onto adjacent cells along cell boundaries. A more extensive area of ornamentation at mid-valve with a dense array of bell and discoid thickening along axes with a more or less longitudinal orientation, not clearly related to cell boundaries, here the thickenings fl are slightly onto the inner radial cell wall. Th e precise relationship of the thickening to inner layer cell walls could not be resolved.
Elaters and pseudoelaters on familiar pattern of 5 (2) and 4 (2), with similar opposite valve pairs, two bearing fi ve elaters, one attached at the valve apex and two each side close to the valve apex, the other valve pairs ( Figure 2F) lacking the apical elater, all valves with two pseudoelaters attached by their length to the valve inner layer. Elaters with weak unihelical thickening.
Distribution and habitat. Lejeunea hodgsoniana is known from a number of locations in New Zealand ranging from latitude 29°14'39"S in the Kermadec Islands to latitude 44° 20'S on Pitt Island in the Chatham Islands. In the northern half of the North Island, it is recorded from off -shore islands on the eastern coast from Poor Knights Island, south through the islands of the outer and inner Hauraki Gulf including the Mokohinau Islands, Hen and Chicken Group, Little Barrier Island and Th e Noises, and from the Mercury Islands Group and Mayor Island east of the Coromandel Peninsula. Th ere are also a small number of northern mainland collections from North Cape south to Port Waikato and Hamilton. In the southern North Island, locations are mainly coastal in the vicinity of Wellington, including on Mana Island. On the South Island it is known from a single collection from the base of Farewell Spit. Elevation is generally less than 100 m with the altitudinal range from 1m to about 520 m, the latter in the Kermadec Islands.
Four of the collections are from shaded stream bed rock, serpentinite at North Cape, basalt or basaltic andesite elsewhere. In most of its locations, however, Lejeunea hodgsoniana has been corticolous in coastal forest or scrub. Species of Melicytus, M. aff .   for the bryophyte collection of the Field Museum of Natural History, Chicago (F) is: http://emuweb.fi eldmuseum.org/botany/search_bryo.php Recognition. Lejeunea hodgsoniana is a distinctive species that can be recognized by a number of features that are unique among southern temperate Australasian Lejeunea : 1) the habit of shoots, with relatively large leaf-lobes closely appressed to the substrate is characteristic; 2) the multicellular, triangular fi rst lobule tooth having a base up to four cells broad, is unique among Australasian species; 3) the elliptic-ovate, deeply divided underleaves with lobes capped (typically) by a single pointed cell are also unusual, occurring in no other Lejeunea from New Zealand; 4) the pentacarinate perianth with dorsal carina reduced or absent is also unusual, but not unique. Th e triangular, multicellular fi rst lobule tooth, is not unique to L. hodgsoniana but is shared by at least two other Lejeunea species, L. bidentula Herzog and L. kodamae Ikegami & Inoue. However, Lejeunea hodgsoniana diff ers from both in details of the lobule and underleaf, and in the overall size of the plants. Th e lobule second tooth in L. hodgsoniana is never well developed, at best it is a broad, low and triangular with a weakly obtuse apex. Both L. bidentula and L. kodamae have a prominent, readily identifi able second lobule tooth, which is triangular in both species and has an acute to obtuse apex (Asthana and Saxena 2011). Th e underleaves of L. bidentula are shallowly bifi d and broadly ovate, and those of L. kodamae are squat, almost rotund but for the sinus, in contrast to those borne by L. hodgsoniana. Both L. bidentula and L. kodamae, with shoots 0.7-0.9 mm wide, are smaller plants than L. hodgsoniana whose shoots frequently attain widths of 1.5 mm. Conservation. Lejeunea hodgsoniana is widely distributed in coastal and lowland habitats in northern and southern parts of the North Island. It is abundant in mahoe dominated forests on the mainland and many off shore islands, including large areas within the conservation estate such as Hauturu and the Poor Knights Islands. Th e species occupies a wide range of forest habitats associated with high light environments, including forest edges, riparian vegetation, successional forest, and fl oodplain scrub. Within these vegetation types L. hodgsoniana can be found in highly disturbed remnants, as well as original stands, for instance coastal forests at Bream Tail, Northland. As a result, we consider this species to be Not Th reatened according to the New Zealand Th reat Classifi cation System (Townsend et al. 2008).

Key to species with multicellular, triangular fi rst lobule tooth in SE Asia and Australasia
Variation. Th roughout its range, there appears to be little variation from the range of variability expressed in the type material. In contrast to the usual weakly bulging leaf lobe cells, those in the sample on stream basalt from Motion Creek in Auckland, AK 303709, are moderately bulging giving a moderately crenulated margin to the lobes. Variation otherwise is in the size and shape of the perianth before sporophyte enlargement. Th e perianths in a sample from the Spicer Botanical Park in Porirua, WELT H012566, lacked the usual distinctly obcordate profi le with the rostrum borne in a depression between the rounded apices of the lateral carinae. Instead, the apex of the perianth is truncate with rounded lateral carina apices. Th e rostrum is longer than usual at ca. 60 μm and the apical depression absent or almost so. Perianths in the samples AK 313726 from the summit of Raoul Island in the Kermadec Islands and AK 291289 from Lady Alice Island have similar truncate apices with a small or absent depression and, in the Kermadec sample, were smaller than usual at 350 μm high × 200 μm wide. study of the botany of the northern off -shore islands has provided at AK the extensive records of their bryophyte diversity and distribution. Th anks are due also to Graham Pritchard for his recent collection, now in WELT, extending the range of the species to the South Island, and to Peter de Lange for his extensive collection of bryophytes from the Chatham and Kermadec Islands.
Our thanks are expressed to Ewen Cameron and Dhahara Ranatunga at AK for the loan of their collection of this species, to Anthony Kusabs at WELT for his facilitation of this loan, and to Jessica Beever for additional location data on some early collections. During the preparation of this paper, David Glenny, Patrick Brownsey, Leon Perrie and Carlos Lehnebach gave valuable advice and support.
Th anks are also expressed for helpful comment of the anonymous reviewer.