Lejeunea perichymidia, M. A. M. Renner, 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 : 205-206

Distribution and Ecology: Lejeunea perichymidia is known from Tasmania and New Zealand.

Lejeunea perichymidia is a facultative epiphyll and, in our experience, exhibits one of the broadest microsite ranges of any Australasian Lejeunea , growing on soil, tree trunks, branches, and leaves of both fern and broadleaved tree and shrub leaves. In all microsites except leaves L. perichymidia grows as part of established, low, bryophyte turfs. On leaves it colonises naked leaf surfaces, and may co-occur with another member of the Lejeunea epiphylla complex, L. demissa , as in the type of L. epiphylla Colenso.

Recognition: Lejeunea perichymidia is a fairly nondescript Lejeunea at first glance, not being endowed with any particularly distinctive features such as unusual lobule shapes, multicellular first lobule teeth, or unusual perianths. Rather it shares with many Lejeunea species the overall appearance of vegetative and reproductive parts, meaning it could conceivably be confused with many other Lejeunea species, hence identification of L. perichymidia is to some extent a matter of elimination. The first check on any suspected individual is to confirm that the leaf-lobe cell surfaces lack ornamentation. In living plants, smooth leaf cell surfaces will co-occur with numerous, small, fusiform, smooth oil-bodies arranged in each cell in a sub-marginal ring. The next check is to confirm that the first lobule tooth is always unicellular, even on the most well developed lobules, and that the perianths, if present, are penta-carinate. The third check is on shoot size, shoots of L. perichymidia are 1.2–1.4 mm wide, while a couple of species with which it could be confused, including L. sp. (p) have smaller shoots. Another character to confirm is the presence of a continuously rounded leaf-lobe margin, one which lacks a distinct rounded to obtuse apex as occurs in, for example, L. demissa . Finally, check the details of the lobule morphology, the second tooth is indistinct and level with the first, the keel should be deeply curved and the lobe-lobule junction is situated in a shallow notch. Lejeunea perichymidia may co-occur with L. demissa , so the possibility that a collection is mixed should always be considered. For guidance distinguishing L. perichymidia from L. demissa , see the recognition section of L. demissa .

Etymology: from the ancient Greek peri – all around and kàma – wave, and idia – the diminuitive suffix; surrounded by small waves referencing the shape formed by the lobe and lobule at their junction.

Conservation: Lejeunea perichymidia was listed in de Lange et al. (2020) as Lejeunea aff. flava (a) (AK 291280; Waitakere), where it was assessed as Not Threatened using the criteria of Townsend et al. (2008). We regard that assessment as appropriate, to which may be appended the qualifier?SO to reflect its Tasmanian occurrences.

Specimens examined: NEW ZEALAND, North Island, Wellington, west side of Hutt Valley , 18.V.1969, B. G . Hamlin 1195 ( WELT-H000645 ); Wadestown, Otari Reserve , 13.IV.1969, B. G .

Hamlin 1056 (WELT-H000471); ibid, B. G . Hamlin 1062 ( WELT-H000477 ); AUSTRALIA: TASMANIA: Cartwright Creek , 42° 56’S 147° 21’E, 25. I .1980, A. V . Ratkowsky H1063 ( HO303361 ) .