Closterium pronum De Brébisson (1856: 157)

Coesel, Peter & Westen, Marien Van, 2013, Taxonomic notes on Dutch desmids V (Streptophyta, Desmidiales): new species, new morphological features, Phytotaxa 84 (2), pp. 46-54 : 46-47

publication ID

https://doi.org/ 10.11646/phytotaxa.84.2.1

persistent identifier

https://treatment.plazi.org/id/03CD87DE-E732-A149-FF72-FAB8FE01FD56

treatment provided by

Felipe

scientific name

Closterium pronum De Brébisson (1856: 157)
status

 

Closterium pronum De Brébisson (1856: 157) ( Figs. 1–4 View FIGURES 1–4 , 13–16 View FIGURES 13–16 )

In Europe, Closterium pronum is a widely distributed species in various types of acidic to circumneutral water bodies. Yet, up to now zygospores of this species were unknown (e.g., Růžička 1977, Coesel & Meesters 2007, Brook & Williamson 2010).

Admittedly, a single figure of a zygospore said to belong to Cl. pronum has been published by Wade (1952) but as adhering gametangium cells have not been depicted identification of that alga cannot be checked.

Recently (April 2012) an abundantly sporulating population of this species in ‘Alenburg’, an artificial pool on former agricultural soil at the Drenthian village of Smilde, was encountered. Morphological characteristics of vegetative cells ( Fig. 1 View FIGURES 1–4 ) fulfilled those stated in the above-mentioned authoritative floras. With an average cell length to breadth ratio of 38.9 (n = 20, SD = 4.0) the similarly shaped, but less slender species Closterium idiosporum West & West (1900: 290) was no serious option ( Růžička 1977). Zygospores appeared to be most peculiar in that they, when maturing, developed marked, undulate, longitudinal ridges on the spore wall.

Initially, the young, elliptic zygospore is smooth-walled ( Figs 2, 3 View FIGURES 1–4 , 13 View FIGURES 13–16 ). Already in this immature stage in its ectoplast a number of longitudinal series of closely set, fine punctae or striae may be distinguished ( Figs. 2 View FIGURES 1–4 , 14 View FIGURES 13–16 ). When maturing, those striae transform into more solid plasma extensions ( Figs. 3 View FIGURES 1–4 , 15 View FIGURES 13–16 ) which in their turn immerse in irregular, sclerotic thickenings forming longitudinal, undulate ridges on the outside of the zygospore ( Figs 4 View FIGURES 1–4 , 16 View FIGURES 13–16 ). At that time, the original smooth exospore wall has completely disappeared as is the case with the initially adhering gametangial cells.

In formation of the above-described costate zygospores Cl. pronum is rather unique. Only Cl. costatosporum Taft (1949: 212) , a North American species whose vegetative cells are quite different from those in Cl. pronum , exhibits somewhat comparable spores (at least in young stage). The peculiar, undulatecostate zygospores of Cl. pronum constitute an important additional differentiating feature with respect to Cl. idiosporum that, in all stages of maturing, is characterized by smooth-walled (at best punctate) zygospores ( Růžička 1977).

For that matter, considering the original illustration of Cl. pronum by De Brébisson (1856) and those in the floras by West & West (1904), Krieger (1937) and Růžička (1977) we cannot preclude that more than one species is at issue. Our vegetative cells most resembled those figured in Krieger (1937, pl. 13: 5, 6) and might represent a separate species.

Kingdom

Plantae

Phylum

Charophyta

Class

Zygnematophyceae

Order

Zygnematales

Family

Closteriaceae

Genus

Closterium

Loc

Closterium pronum De Brébisson (1856: 157)

Coesel, Peter & Westen, Marien Van 2013
2013
Loc

Closterium pronum De Brébisson (1856: 157)

De Brebisson, A. 1856: )
1856
Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF