Heterocladium dimorphum (Heterocladiaceae, Bryophyta) – an old element of the Hungarian bryophyte flora rediscovered

Abstract

. (2016): Heterocladium dimorphum (Heterocladia ceae, Bryophyta) -an old element of the Hungarian bryophyte fl ora rediscovered. -Studia bot. hung. 47(2): 269-278.Abstract: Heterocladium dimorphum is considered to be a data-defi cient moss species that has been neither collected nor observed in the last 46 years in Hungary. During the systematic fi eld studies aimed at exploring the recent bryophyte fl ora of the Kőszeg Mts and in the framework of grid-cell based bryophyte recording, H. dimorphum was discovered in two new locations of the Kőszeg Mts and re-found in one of the old locations in the Visegrád Mts. Th e size of populations is estimated and the habitats are characterized. Illustrations and a short description of the species are provided. Th e previous occurrences of H. dimorphum in Hungary are listed based on the specimens of the bryophyte collection of the Hungarian Natural History Museum, Budapest (BP). Based on the extant populations, the species is considered as endangered (EN).

Keys for the identification of bryophytes occurring in Hungary

“…249-404. gametophyte a thallus gametophyte never a thallus leaves deeply lobed or segmented leaves never deeply lobed or segmented leaves never with costa ( but beware of vitta in Diplophyllum albicans) leaves with or without costa leaves without costa, cells isodiametric, never prosenchymatic leaves without costa, cells prosenchymatic, never isodiametric leaves arranged in 3 ranks, 2 ranks of lateral leaves and 1 rank of (smaller) underleaves, which may be lacking leaves not in 3 or 2 ranks (but beware of Fissidens, Distichium: leaves in 2 ranks, but leaves costate) rhizoids consisting of a single cell each rhizoids made up of more than one cell, with oblique cross-walls seta weak, hyaline, elongating rapidly and dying after a few days seta stout, brown, red, yellow, elongating slowly and long persisting, usually visible for a year spore capsule containing spores and elaters, but without peristomium spore capsule containing spores only, with peristomium in the majority of cases capsule globose or ovoid, without lid, splitting into 4 valves capsule pear-shaped to cylindrical, typically with lid and peristome capsule blackish, without chloloplasts and wall without stomata capsule green with chloroplasts when young, usually brown when ripe, wall often with stomata Thallus simple, furcate, pinnate, palmate or irregularly branched, more than 3 mm wide, glabrous; midrib indistinct or poorly distinct on the dorsal side; gametangia and sporophytes on dorsal side of thallus or on lateral branches.... Minute species, plants only 2-10 ( 12) mm long and 0.2 mm wide; lateral leaves slighty concave, ± transversely inserted, 2-lobed to 1/3-1/2, sometimes Baráth et al (2016).…”

“…. Myurella julacea (r) -Stem leaves plane or slightly concave, patent to squarrose, not imbricate; plants not julaceous.................................................... 5 5 Stem and branch leaves strongly dimorphic; stem leaves reflexed, abruptly contracted from broad base; branch leaves slightly concave, ovate, obtuse or shortly acute............... Heterocladiella dimorpha (Heterocladium dimorphum) (rr) Note: For an account of this species in Hungary, seeBaráth et al (2016).-Stem and branch leaves similar in shape, but differing in size; stem leaves erecto-patent to patent, not reflexed, gradually narrowed to acute apex. Heterocladium heteropterum (rr)Note: For an account of this species in Hungary, see…”