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- A-G
  - Actinotaenium
    - cucurbita
    - cucurbitinum
    - curtum
    - didymocarpum
    - diplosporum (forma maius)
    - inconspiquum
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    - acerosum
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    - striolatum
    - subscoticum
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  - Cosmarium
    - angulare
    - amoenum
    - anceps
    - biretum
    - botrytis
    - brebissonii
    - caelatum
    - cataractarum
    - commissurale
    - connatum
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    - cosmarioides
    - cyclicum
    - denboeri
    - difficile
    - excavatum
    - formosulum
    - granatoides
    - granatum
    - hexalobum
    - holmiense
    - humile
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    - margaritiferum
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    - microsphinctum
    - monomazum
    - nasutum
    - nymannianum
    - obliquum
    - obsoletum
    - obtusatum
    - ornatum
    - ovale
    - paragranatoides
    - perforatum
    - pericymatium
    - portianum
    - protractum
    - pseudoconnatum
    - pseudoinsigne
    - pseudopyramidatum
    - punctulatum
    - pyramidatum
    - quinarium
    - ralfsii
    - regnellii
    - regnesi
    - reniforme
    - sphyrelatum
    - striolatum
    - subexcavatum
    - subgranatum
    - subprotumidum
    - taxichondriforme
    - tetrachondrum
    - turpinii
    - ungarianum var. subtriplicatum
    - venustum
  - Cosmocladium
  - Cylindrocystis
    - brebissonii
    - gracilis
  - Desmidium
  - Docidium
    - baculum
    - undulatum
  - Euastrum
    - ampullaceum
    - ansatum
    - bidentatum++
    - binale
    - biscrobiculatum
    - coeselii
    - crassum
    - denticulatum
    - dubium
    - elegans
    - gayanum
    - germanicum
    - humerosum
    - insigne
    - insulare
    - lacustre
    - luetkemuelleri
    - oblongum
    - pectinatum
    - pinnatum
    - pseudotuddalense
    - pulchellum
    - ventricosum
    - verrucosum
  - Gonatozygon
- H-R
  - Haplotaenium
    - minutum
    - rectum
  - Heimansia
    - pusilla
    - species
  - Hyalotheca
    - dissiliens
    - mucosa
  - Mesotaenium
  - Micrasterias
    - americana
    - apiculata
    - brachyptera
    - crux-melitensis
    - denticulata
    - fimbriata
    - furcata
    - jenneri
    - oscitans
    - papillifera
    - pinnatifida
    - radiosa
    - rotata
    - thomasiana
    - truncata
  - Netrium
  - Penium
  - Pleurotaenium
    - archeri
    - coronatum
    - ehrenbergii
    - nodulosum
    - simplicissimum
    - trabecula
    - truncatum
  - Roya
    - closterioides
    - obtusa
- S-X
  - Sphaerozosma
  - Spirotaenia
  - Spondylosium
    - ellipticum
    - pulchellum
  - Staurastrum
    - alternans
    - arachne
    - bloklandiae
    - brachiatum
    - brebissonii
    - brevispina
    - chaetoceras
    - cingulum
    - controversum
    - crassangulatum
    - diacanthum
    - dilatatum
    - echinatum
    - elongatum
    - furcatum
    - furcigerum
    - habeebense
    - heimerlianum
    - hirsutum
    - hystrix
    - lapponicum
    - levanderi
    - margaritaceum
    - monticulosum
    - pileolatum
    - pingue
    - polytrichum
    - punctulatum
    - pyramidatum
    - scabrum
    - sexcostatum
    - spongiosum
    - teliferum
    - tetracerum
    - vestitum
  - Staurodesmus
    - convergens
    - cuspidatus
    - dejectus
    - dickiei
    - extensus
    - glaber
    - mucronatus
    - omearae
    - patens
    - pterosporus
    - triangularis
  - Teilingia
    - granulata
  - Tetmemorus
  - Tortitaenia
  - Xanthidium
    - antilopaeum
    - armatum
    - basidentatum
    - bifidum
    - cristatum
    - fascicultum
    - octocorne
    - tenuissimum
    - variabile
Year
Additions

Cosmarium regnesi
Image © Marien van Westen

Cosmarium regnesi. Notice widely open, U-shaped sinus, median indentation at the apex and stout (intra)marginal granules.

Cell dimensions (L x B): 13 x13 µm

Image © Alfred van Geest

Another cell of C. regnesi in which the cell wall granules stand out by iron impregnation.

Desmid of the month
April 2020

Cosmarium regnesi

Cosmarium regnesi is a small-sized species that may readily be distinguished by its widely open, U-shaped sinus. Semicells are about rectangular in shape with a wide indentation in the middle of the apex and a number of tubercle-like marginal and intramarginal granules giving rise to a somewhat undulate appearance of the semicell outline. In the Netherlands, C. regnesi is of incidental occurrence in both circumneutral, mesotrophic peat pits and acidic, oligotrophic moorland pools.

tSEM picture of C. regnesi in frontal view.

SEM picture of C. regnesi in oblique lateral view.

Desmid of the month April 2020

Cosmarium regnesi

Desmid of the month
April 2020