Rhynchostegiella azorica Hedenäs & Vanderpoorten, 2015

Vanderpoorten, Alain, Patiño, Jairo, Dirkse, Gerard, Blockeel, Tom & Hedenäs, Lars, 2015, Early divergence of an Azorean endemic species in the moss genus Rhynchostegiella (Brachytheciaceae), Phytotaxa 210 (1), pp. 60-69 : 65-66

Rhynchostegiella azorica Hedenäs & Vanderpoorten sp. nov. ( Fig. 2 )

Similar in leaf morphology to R. curviseta but differing from the latter by its long acuminate leaf apex. Characterized by one synapomorphic mutation from A to C in the trn L region and another from G to A in the atp b_ rbc L spacer.

Holotype: PORTUGAL. Azores: Flores, between Mosteiro and Lajedo, 39°N 24’, 31°W 14’, on rocks within a lowland vegetation dominated by Pittosporum undulatum , Erica azorica, Hedychium gardnerianum, Cyrtomium falcatum , and Selaginella kraussiana , January 2009, Vanderpoorten FLOR 2 ( LG).

Plants tiny, rigid, wiry, green or dark green, irregularly and sometimes repeatedly branched. Stem without central strand, cortex of 2–3 layers of small and slightly incrassate cells, cells inside large, thin-walled or slightly incrassate; pseudoparaphyllia foliose, triangular; paraphyllia absent; rhizoids inserted below leaves, red-brown, not or weakly branched, smooth; axillary hairs 1–2 per axil, strictly axillary or inserted on stem shortly above leaf, with 1–2 upper cells, 7.5–8.5 μm wide, hyaline, basal cell short-rectangular, hyaline or pale brownish. Stem leaves erecto-patent to spreading, straight or somewhat homomallous, (0.20-) 0.42–1.25 mm long, with a length to width ratio of 4.0–6.5, narrowly triangular, with long-acuminate apex (17–27 μm wide at 100 μm and 35–55 μm at 200 μm below apex), sometimes keeled near base, otherwise plane; costa single, ending 25–80% way up leaf, diffusely delimited, 19.0–31.5 μm wide near insertion, surface cells on both ad- and abaxial sides similar to adjoining lamina cells, smooth or occasionally ending in a spine; margin denticulate or finely and obtusely so above, entire or almost so below, plane; median lamina cells 25.0–82.0(-89.0) x 4.0–8.5 μm, linear, with a length to width ratio of 4–11 and shortly tapering ends, slightly incrassate, eporose, smooth; basal cells rectangular or elongate-rectangular, shorter and slightly wider than mid-leaf cells, incrassate or slightly so, eporose; alar cells undifferentiated from other basal cells or quadrate, shortly rectangular, or rectangular, slightly incrassate, eporose, and forming a weakly differentiated oblong group along leaf margin, extending from leaf margin 40–60% of distance to costa at insertion, not decurrent. Branch leaves similar to stem leaves or more strongly denticulate, proximal branch leaves triangular, acute or acuminate. Autoicous, or some shoots with only perichaetia. Perigonia laterally inserted on stem, intermixed with perichaetia; perigonial leaves from broad basal part suddenly narrowed to distinct acumen, acuminate; margin entire, bordered; paraphyses present, thin-walled. Perichaetia laterally inserted on stem, inner perichaetial leaves straight and erect or upper leaf portions slightly homomallous or spreading, from narrowly triangular or oblong-triangular base gradually narrowed to narrowly acuminate apex, smooth; costa absent or single, very short and indistinct; margin irregularly finely denticulate above; paraphyses 3–5-celled, thin-walled, sparse. Calyptra cucullate, 2–3 stratose, cells homogeneous, smooth, naked. Seta 3–8 mm, red, slightly (visible in compound microscope) to clearly rough, with narrow central strand and a cortex of 2–3(-4) layers of small and incrassate cells, when dry untwisted or dextrorse. Capsule of Brachythecium - type or sometimes short-cylindrical and curved in transition to seta, not furrowed, not constricted below mouth when dry, orthogonal; lid rostrate; annulus separating, of (1-)2 rows of cells; exothecial cells 19–48 x 12–23 μm, varying around quadrate to rectangular, thin-walled, but strongly collenchymatous with superficial thickenings, below mouth 0–2 rows of small, transversely oblong to shortly rectangular cells; stomata round-pored. Exostome well developed, reddish orange, on lower outside cross-striolate, sometimes with minute papillae on top of striolations, above papillose, not furrowed, margin weakly dentate above, border narrow below, gradually disappearing above zone of transition in outside ornamentation, primary peristomial layer normally developed. Endostome basal membrane 36–46% of endostome height, endostome yellow, finely papillose above, very finely so below, cilia 1–2, when two often merged, longest ones as long as processes or almost so, nodose, processes narrow and narrowly (<3 μm) perforate. Spores 11.5–16.0 μm, almost smooth, mature in winter half-year.

Additional specimens seen: PORTUGAL. Azores: Flores, Fajazinha, Poço das Patas , 260m, 39°N 25’15’’, 31°W 14’08’’, January 2009, Vanderpoorten 12/2, 12/11, 12/25, 12/26 ( LG) ; Flores: Faja Grande , 160m, 39°N 29’00’’, 31°W 15’19’’, January 2009, Vanderpoorten 14/3 ( LG) ; Faial : 260m, 38°N 45’22’’, 28°W 45’37’’, 8 March 2012, Vanderpoorten & Patino RHY832 ( LG) ; Terceira: Agualva , 70m, 38°N 47’31’’, 27°W 11’17’’, January 2009, Vanderpoorten 18/1 ( LG) ; Faial , 1937, H. Persson sn (S-B196675) ; Faial, Cedros , 1000 m, 19 March 1992, H. Greven sn (herb. Dirkse 29583) ; Terceira, Santa Barbara , 24 April 1937, H. Persson sn, (S-B9092) .

Figures

FIGURE 2. Rhynchostegiella azorica Hedenäs & Vanderpoorten (from Vanderpoorten FLOR2, holotype).A, habit; B, apex of branch; C, stem leaves; D, capsule lid; E, stem leaf apex; F, leaf lamina cells from mid-leaf; G, alar cells; H, axillary hairs. Scales: a, 2 cm (A); b, 2 mm (D), c, 100 μm (E–H); d, 450 μm (B, C).