Staurastrum cf. cyrtocerum Brébisson

Adam, Chaidir, Kenins, Alex & Prabowo, Danang A., 2025, Diversity and new records of desmids (Zygnematophyceae, Charophyta) in Central Kalimantan, Indonesia, Phytotaxa 691 (2), pp. 125-150 : 145-146

Staurastrum cf. cyrtocerum Brébisson

Coesel & Meesters 2013, p. 88, pl. 78, figs 1, 2.

Fig. 8e

Comments: We have tentatively assigned these forms as Staurastrum cf. cyrtocerum Brébisson on the basis of the similar cell morphology: tri- and quadri-radiate, along with the processes being characteristically convergent and slightly inflexed. Occurs in slightly acidic to slighlty alkaline, mesotrophic waterbodies ( Coesel & Meesters, 2013).

Distribution: Coesel & Meesters (2013) considered it distribution as potentially cosmopolitan but not well understood due to its confusion with other, morphologically-similar species.

* Staurastrum distentum Wolle

Ling & Tyler 2001, p. 221, pl. 135, figs 5 & 6.

Fig. 8f

Comments: The processes are much shorter and the ornamentation is considerably diminished in some of our specimens.

Distribution: A new record for Kalimantan. Previously reported from Sumatra by Scott & Prescott (1961). Mostly (sub)tropical in distribution: North America, South America ( Brazil), Africa, China, Japan, Australia (Northern Territory).

* Staurastrum podlachicum Eichler & Gutwiński

Coesel & Meesters 2013, p. 134, pl. 65, figs 9–12.

Fig. 8g

Comments: Coesel & Meesters (2013) noted that this species may be a nascent stage of Staurastrum forficulatum P. Lundell. Similarly, Ling & Tyler (2001) included morphologically comparable forms as Staurastrum ehrengergianum (Nägeli) Archer , and stated that their material with the undeveloped processes were identifiable with the “ Staurastrum oligacanthum var. podlachicum (Eichler & Gutwiński) West & G.S.West morpha” described in Croasdale et al. (1994). Found in acidic, oligotrophic waters ( Coesel & Meesters 2013).

Distribution: North America, Europe and New Zealand. Australia is included when considering the reduced forms of S. ehrengergianum reported by Ling & Tyler (2001). A new record for Kalimantan and Indonesia.

* Staurastrum retusum W.B.Turner

Coesel & Meesters 2013, p. 142, pl. 33, figs 4–11.

Fig. 8h

Comments: Found in acidic, oligo-mesotrophic water bodies ( Coesel & Meesters, 2013). Only one specimen was found during our study indicating its rarety in nature. Consequently detailed observation could not be made, especially at the apical view. However, the specimen closedly resembled those of S. retusum reported in Coesel & Meesters (2013). More sampling effort for this species is required to determine it distinction to other morphologically similar species (e.g., species of Cosmarium ).

Distribution: A new record for Kalimantan. Regarded by Coesel & Meesters (2013) as very common in the INMAR desmid bioregion and practically rare elsewhere.

Figures

FIGURE 8. Pleurotaenium: (a) P. nodosum var. gutwinskii Willi Krieger, (b) P. ehrenbergii (Ralfs) De Bary, (c) P. ovatum var. inerme Möbius.Staurastrum: (d) S. bifidum Brébisson ex Ralfs, (e) S. cf. cyrtocerum Brébisson, (f) S. distentum Wolle, (g) S.podlachicum Eichler & Gutwiński, (h) S. retusum W.B.Turner. Staurodesmus: (i) S. convergens (Ehrenberg ex Ralfs) S.Lillieroth, (j) S. patens (Nordstedt) Croasdale. Tetmemorus: (k) T. cf. granulatus Brébisson ex Ralfs.