Nitella opaca (C.Agardh ex Bruzelius) C.Agardh 1824

Publication Details
Nitella opaca (C.Agardh ex Bruzelius) C.Agardh 1824: 124

Published in: Agardh, C.A. (1824). Systema algarum. pp. [i]-xxxvii, [1]-312. Lundae [Lund]: Literis Berlingianis [Berling].

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Publication date: probably September 1824

Type Species
This is the type species (lectotype) of the genus Nitella.

Status of Name
This name is of an entity that is currently accepted taxonomically.

Basionym
Chara opaca C.Agardh ex Bruzelius

Type Information
Type locality: "Habitat in aquis quietis, in Scania non rara. Mense Julio fructum fert."; (Bruzelius 1824: 17)

Origin of Species Name
Adjective (Latin), darkened, dull, not shining, opaque (Stearn 1983).

General Environment
This is a freshwater species.

Description
The plants are 5 - 50 cm high and green. The axis is up to 1 mm in diameter. The branchlets are simple or divided once with one-celled end segments. The species is dioecious. The gametangia are evenly distributed or in heads. The oogonia are solitary or geminate, up to 700 m long and 600 m wide. The oospore is dark - chestnut to black in colour and the antheridium is large, up to 800 m in diameter.

Habitat
Nitella opaca is found in many different habitats; lakes, brooks and it seems to prefer oligotrophic waters (Lobelia-lakes), but has also been reported from slightly brackish water. In Norway the species is quite common in high-mountain lakes and has here been found down to 17 m depth and up to 1250 m altitude. N. opaca is perennial, and has mature gametangia from May to August and ripe, black oospores from June to September.

Created: 12 April 2002 by M.D. Guiry.

Last updated: 17 January 2025

Verification of Data
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Taxonomic note
"Nitella opaca is combined with the monoecious N. flexilis by several European authors (e.g., Cirujano et al., 2008; Moore, 1986), following Wood's opinion about the significance of this character for charophytes in general (Wood, 1962). However, his opinion was criticised immediately after being published in more detail (Wood, 1965) by Sarma and Khan (1967), targeting on the consistent difference in chromosome number between N. flexilis (n = 12) and N. opaca (n = 6)." (Pall & al. 2024) - (22 January 2025) - M.D. Guiry

Distributional note
"Nitella opaca is a cosmopolitan species. Whereas it occurs almost everywhere in the northern hemisphere, findings in the southern hemisphere are documented only for the south-eastern and the south-western part of South America (Korsch, 2018; Blindow et al., 2018, respectively). In Europe the species can be found in nearly every country, records are missing only for Luxembourg, Kosovo and Moldova. The species may occur in Estonia as well but was not separated from N. flexilis in the recent monitoring therefore data from Estonia were not included in Fig. 64.4. Data from the Mediterranean and Maghreb can be found in Bla%u017Een%u02C7cic et al. (2006), Bazzichelli and Abdelahad (2009), Daoud-Bouattour et al. (2011), Mouronval et al. (2015), Muller et al., (2017), and Becker (2019)." (Pall & al. 2024). - (22 January 2025) - M.D. Guiry

Habitat note
Mostly in temporary habitats, and occasionally in permanent lakes, down to 12 m depth; prefers cold waters, with pH of 6-8 (Muller et al., 2017). - (01 November 2017) - G.M. Guiry

Conservational note
"Nitella opaca is frequently found all over Europe and, given its very broad niche, it might be surprising that the species is red-listed so often regionally as well as nationally. The reason for this is the declining trend. Being at least one of the most frequent, if not the most frequent species in many European countries, habitat loss and habitat destruction took their share the past 70 years. As well the European-wide loss of small water bodies is responsible for the decline of suitable sites for N. opaca (Becker and Wolff, 2016). Drainage, eutrophication resulting from agricultural activities and intensification of the use of water bodies for fishery and recreation are also threatening the stands (Becker and Wolff, 2016). On the other hand, newly created quarry ponds and waterbodies for conservation measures have been colonised by N. opaca during the last decade. Given the large distribution area and broad ecological niche, the species itself probably is not at acute risk on a European level. However, effective measures should be taken to stop this trend of decline in number and sites in order to prevent further fragmentation of populations." (Pall & al. 2024). - (22 January 2025) - M.D. Guiry

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Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 17 January 2025. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 31 March 2025

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