Micrasterias jenneri var. semicirculare G.J.P.Ramos & C.W.N.Moura, 2019

Ramos, Geraldo José Peixoto, Costa, Fabiana De Matos, Santos, Maria Aparecida Dos & Moura, Carlos Wallace Do Nascimento, 2019, Taxonomic novelties, new records, and rare species of desmids from the Chapada Diamantina region, Brazil, Phytotaxa 391 (3), pp. 185-196 : 192

publication ID

https://doi.org/ 10.11646/phytotaxa.391.3.2

DOI

https://doi.org/10.5281/zenodo.13727247

persistent identifier

https://treatment.plazi.org/id/FB1D87F6-FFCF-FFC9-FF7D-D719FB472366

treatment provided by

Felipe

scientific name

Micrasterias jenneri var. semicirculare G.J.P.Ramos & C.W.N.Moura
status

var. nov.

Micrasterias jenneri var. semicirculare G.J.P.Ramos & C.W.N.Moura , var. nov. ( Figs 51–54 View FIGURES 51–65 )

Diagnosis— This variety differs from the nominate variety by having a semicircular outline, with lateral lobes broadly rounded, whereas M. jenneri var. jenneri has an oblong outline and lateral lobes concave. Another difference from the nominate variety is the incision between the lateral lobes that is about the same size as the incision between the apical and basal lobes, being shorter in the nominate variety

Cell dimensions: length 145–165 μm, breadth 109–123 μm, apical lobe 32–64 μm, isthmus 32–36 μm.

Holotype: material numbered ( HUEFS 244148 About HUEFS !) deposited at Herbário da Universidade Estadual de Feira de Santana , population illustrated here in LM ( Figs 51–54 View FIGURES 51–65 ).

Etymology: The epithet refers to semicircular outline of the cells.

Type locality and habitat characteristics: Collected at “Vale do Capão”, Palmeiras, Bahia state, Brazil. Lat. 12º 30’ 31” S, Long. 41º 29’ 10” W. Sample collected by G. J. P.Ramos s/n ( HUEFS 244148) on 26 February 2017. Micrasterias jenneri var. semicirculare occurred in periphyton, with quiet and warm waters, associated to filamentous algae.

Notes: Micrasterias jenneri Ralfs (1848: 76) has been rarely reported in floristic studies in South America, and the few existing records are from material collected in Brazil ( Bicudo & Ventrice 1968, Bicudo & Picelli-Vicentim 1988, Moresco et al. 2009, Bicudo et al. 2015), and generally identified as Micrasterias jenneri var. simplex West (1890: 287) .

Tomaszewicz (1977) and Sormus (1991) discussed the relationships between the nominate variety and var. simplex , and concluded that the latter variety is a developing morphological expression (i.e., an immature form) of the former, in which the lateral lobes have not undergone a division process. Currently, Micrasterias jenneri var. simplex is considered a taxonomic synonym of Micrasterias jenneri Ralfs ( Guiry & Guiry 2018) .

Regarding the new variety, Micrasterias jenneri var. semicirculare , a population analysis (ca. 50 specimens examined) indicated that the semicircular outline, broadly rounded in the lateral lobes, is consistent and distinct from the nominate variety (which has an oblong outline) described by Ralfs. The lateral lobes are also slightly different, being more concave in the nominate variety than in var. semicirculare . We therefore consider those features sufficient to propose this taxon as a new variety.

Micrasterias jenneri var. semicirculare can be confused with M. denticulata Brébisson ex Ralfs (1848: 70) , although the latter differs mainly by having lateral subdivided into lobules of the third or fourth order.

LM

Secçáo de Botânica e Ecologia

G

Conservatoire et Jardin botaniques de la Ville de Genève

J

University of the Witwatersrand

P

Museum National d' Histoire Naturelle, Paris (MNHN) - Vascular Plants

HUEFS

Universidade Estadual de Feira de Santana

Kingdom

Plantae

Phylum

Charophyta

Class

Conjugatophyceae

Order

Zygnematales

Family

Desmidiaceae

Genus

Micrasterias

Loc

Micrasterias jenneri var. semicirculare G.J.P.Ramos & C.W.N.Moura

Ramos, Geraldo José Peixoto, Costa, Fabiana De Matos, Santos, Maria Aparecida Dos & Moura, Carlos Wallace Do Nascimento 2019
2019
Loc

Micrasterias jenneri var. semicirculare

Ralfs, J. 1848: )
1848
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