Syzygiella manca (Montagne, 1856) Jack & Stephani, 1892

Váňa, Jiří, Feldberg, Kathrin, Söderström, Jochen Heinrichs Lars, Hagborg, Anders & Konrat, Matt Von, 2014, Notes on Early Land Plants Today. 55. New taxa and synonyms in Adelanthaceae (Marchantiophyta), Phytotaxa 173 (1), pp. 80-86 : 81

Syzygiella manca

Recently Gradstein (2013) placed S yzygiella geminifolia ( Mitten 1864a: 164) Stephani (1902a: 467) in the synonymy of Syzygiella manca ( Montagne 1856:63) Jack & Stephani (1892: 14) . His opinion was based on a single specimen collected in Ecuador (Nöske 163, GOET) which he had assigned to Syzygiella manca . This specimen was resolved in a clade with African accessions of Syzygiella geminifolia by Feldberg et al. (2010a), who noted that (l.c., p. 302) “An Ecuadorian accession is nested in the Syzygiella geminifolia clade and morphologically inseparable from the African accessions”.

Syzygiella geminifolia and Syzygiella manca were separated by assumed differences in stem cross section, undulation of leaves, and cell surface ( Inoue 1966). However, our study of a larger series of specimens from the African mountains and South American material collected in the Andes ( Peru to Venezuela) and on Mt. Roraima (Guayanan/Brazilian border), shows that Syzygiella manca is highly variable in terms of gametophyte size, stem cross section, dimensions and also shape and undulation of leaves, and cell size. The South American taxa placed in the synonymy of Syzygiella manca [ Syzygiella quelchii Stephani (1901a: 96) , Syzygiella subundulata Inoue (1966: 188) and Syzygiella colombiana Robinson (1967: 322) ] are possibly habitat modifications caused by somewhat different growth conditions; as are African populations [ Syzygiella geminifolia , Syzygiella ruwenzorensis Stephani (1911: 117) ]. Large, well developed plants have a 2-3 layers thick stem cortex [ Syzygiella manca , Syzygiella colombiana Robinson (1967: 322) ], smaller and younger plants only +/- one, often ill-defined layer of cortical cells ( Syzygiella geminifolia , Syzygiella subundulata ). Some phenotypes have leaves with an undulate, reflexed ventral margin ( Syzygiella subundulata , Syzygiella colombiana and the isolectotype, but not the lectotype of Syzygiella quelchii ). The cell surface is usually smooth; trigones are large and nodulose. According to the key to the species of Syzygiella sect. Anomalae of Inoue (1966: 183), Syzygiella manca should have a smooth cell surface (cuticle) and Syzygiella subundulata a verrucose cell surface. However, in the original description of Syzygiella subundulata the cell surface is described as “cuticula laevi” (Inoue, l.c. p.188) or “cuticle smooth” (p. 190). Inoue (1966) was not able to examine the type of Syzygiella quelchii . He wrote that “according to the original description, this species seems to belong to sect. Anomalae and is very close to Syzygiella manca and Syzygiella anomala ” ( Inoue 1966: 210) . Grolle (in sched. 2002 and in So & Grolle 2003), after revising the “ holotype ” of Syzygiella quelchii (BM; must be regarded as lectotype instead), confirmed the conspecificity of Syzygiella quelchii and Syzygiella manca . The type of Syzygiella quelchii was collected in the same locality as the type of Syzygiella subundulata . Robinson (1967) apparently did not study the types of Syzygiella quelchii and Syzygiella subundulata . According to his description and determination key, plants of Syzygiella colombiana have larger leaves (3.5-4.0 mm long vs. 2.2-3.0 mm long) and a broadly auriculate ventral leaf base. He considered the leaf base of Syzygiella subundulata not auriculate, in contrast to that of Syzygiella colombiana . In fact, plants from Mt. Roraima identified as Syzygiella quelchii are somewhat smaller than the Colombian ones (also additional specimens from Colombia). Colombian and Guyanan plants are linked by a Venezuelan specimen ( Venezuela, Amazonas, Dept. Rio Negro, Cerro de Neblina, 1985, Halling 4355, F, NY) assigned to Syzygiella quelchii which is intermediate in size. All examined specimens, incl. the type of Syzygiella subundulata , have auriculate ventral leaf bases (cf. Inoue 1966: 190, who described ventral bases of leaves as “ampliate”). The only existing difference between Mt. Roraima specimens assigned to Syzygiella quelchii or Syzygiella subundulata and Colombian plants of Syzygiella colombiana is the size of the gametophytes, a character which is possibly influenced by environmental conditions and not suitable to separate taxa. A large variation in size was already demonstrated for Syzygiella concreta ( Feldberg et al. 2011) . In the absence of comprehensive molecular data we accept a wide species concept for Syzygiella manca .