Austral Hepaticae. 28. Plagiochila bazzanioides Engel & Merrill, a Remarkable New Species of Plagiochilaceae from New Zealand

Abstract

Plagiochila bazzanioides, a new species from New Zealand, is described and illustrated. Plagiochila is the largest genus of hepatics, with perhaps as many as 1600 described species (Bonner, 1962). As in other species-rich groups, the actual number of species will probably prove to be considerably less. According to Schuster (1980: 348), total number of valid species of Plagiochila may prove to be below 500. The genus is widely distributed and essentially cosmopolitan. Centers of taxic diversity are chiefly in the Neotropics and southeast Asia, and the genus is rather poorly represented in temperate areas. For example, Schuster (1980) included 20 species for North America, and Inoue and Schuster (1971) included 25 species from temperate Australasia. This paper describes an additional distinctive species occurring in New Zealand, as follows. Plagiochila bazzanioides Engel & Merrill, sp. nov. TYPE: New Zealand. North Island: North Auckland Province, Rangitoto Island, immediately E of Auckland, 50-160 m, 4 Feb. 1995, Engel 20769 (holotype, F; isotype, CHR). Figure 1. Species insignis foliis falcatis canaliculatis decurvatis, marginis foliorum pectinatis dentibus gracilibus uncinatis, ramis plurimis flagelliformibus, androeciis intercalaribus, paraphylliis caulis dentatis lamelliformibus a species nobis notis optime distincta. Plants bazzanioid in habit, ascending, without differentiation of a horizontal leafless axis, rich, deep olive green; leafy shoots medium, to 5 mm wide. Stems with paraphyllia inconspicuous, typically consisting of a single, short, sharply toothed lamella adjacent to dorsal leaf base; stem in cross section with cortical cells in (2)3 layers of very thick-walled cells, the medullary cell walls thin, colorless. Branching exclusively lateral-intercalary, sometimes with geotropic, microphyllous, rhizoidous, flagelliform, lateral-intercalary branches. Rhizoids rather dense on leafy shoots. Leaves horizontally spreading to ventrally secund, often conspicuously falcate, spreading at + right angles to stem, closely imbricate, frequently canaliculatesubtubular to the tips, the dorsal margins narrowly recurved and forming a distinct convex fold, lending the shoot a tightly pleated aspect in dorsal view, in ventral aspect the ventral margin aligned at right angles to the stem except for the basal sector, which lies parallel to the stem, in ventral view the ventral margins pectinate-toothed, the teeth often stiffly reflexed and hooked dorsally, the ventral surface of stem moderately or totally hidden; leaf insertion elongated, distinctly straight and steeply oblique for most of its length, abruptly recurved at ventral end; leaves asymmetrically narrowly elongate-trapezoidal, tapering to a markedly narrow, almost parallel-sided distal 0.2 to 0.3; leaf apex narrowly rounded to truncate, tending to become bidentate by 2 conspicuous, often diverging apical teeth that are often larger than adjacent teeth; dorsal margin nearly straight to broadly curved inward, with + regularly spaced, slender, recurved teeth to the base (best seen in ventral aspect); ventral margin + straight from a subauriculate base, conspicuously ciliate-dentate particularly in basal portion, the teeth stiffly reflexed (hooked dorsally), the margin often entire or subentire in the distal 0.5, decurrent, the decurrent strip dentate. Marginal teeth slenderly acuminate, 1-2 cells wide at the base, consisting almost entirely of a uniseriate row of 46 distinctly thick-walled cells, the terminal cell elongate, to 4.2:1. Underleaves consisting of an amorphous clump of cells, in part short-filamentous, at end of decurrent ventral leaf base. Cells in median portion of leaf thin-walled and with trigones bulging to knotlike; median cells 20-29 /m wide x 30-36 /m long; cells of leaf bases scarcely elongated and not forming a basal field; cuticle smooth. Asexual reproduction lacking. $ Plants + smaller than the Y ones, mostly simple; androecia on main shoot and leading lateralintercalary branches, becoming intercalary in position (often with several successive androecia occurring on a stem or branch); bracts many, in up to 15 pairs, strongly saccate in dorsal half of base; apex broadly rounded, spatulate, entire; ventral marNovoN 9: 29-31. 1999. This content downloaded from 207.46.13.126 on Sat, 24 Sep 2016 04:54:34 UTC All use subject to http://about.jstor.org/terms