Compare

Planothidium lanceolatoides is very similar, in particular, rapheless valves are difficult to distinguish. The central area of the raphe valve of P. lanceolatoides is variable in shape and has 1-4 dash-like marks on the internal cell wall.

Other Planothidium species (P. frequentissimum, P. biporomum and P. potapovae) have a cavum, but they are much smaller. Planothidium delicatulum is also much smaller, and lacks a cavum.


LM scalebar = 10 µm
Planothidium apiculatum LM3 Planothidium apiculatum LM1 Planothidium apiculatum LM4 Planothidium apiculatum LM6 Planothidium apiculatum LM2 Planothidium apiculatum LM5 Planothidium apiculatum LM7
Length Range
25-31 µm
Width Range
9.0-12.7 µm
Striae in 10 µm
10-12

Planothidium lanceolatoides

(Sovereign) Lange-Bert. 1999

Planothidium lanceolatoide LM1 Planothidium lanceolatoide LM2 Planothidium lanceolatoide LM4 Planothidium lanceolatoide LM3 Planothidium lanceolatoide LM7 Planothidium lanceolatoide LM6 Planothidium lanceolatoide LM5
Length Range
17-36 µm
Width Range
9-13 µm
Striae in 10 µm
11-14

Planothidium frequentissimum

(Lange-Bert. in Krammer and Lange-Bert.) Lange-Bert. 1999

Gs119780 1 Ed Planothidium frequentissimum LM3 Planothidium frequentissimum LM2 Mo000019 1A Ed 5 Planothidium frequentissimum LM1 Gs181995 1B Ed Mo000019  Plfreq 1B Ed
Length Range
5-17 µm
Width Range
3-6 µm
Striae in 10 µm
13-18

Planothidium delicatulum

(Kütz.) Round and Bukht. 1996

Gs181995 2A Gc112144B  Nrsa0167  Pldelic1 Gs134565 1A Gs134565 3 1 Gs134565 6 Gc8031  Sabine  Pldel1B
Length Range
12-20 µm
Width Range
4.7-7.5 µm
Striae in 10 µm
13-15

Planothidium potapovae

C.E.Wetzel and Ector 2019

Gsn23403  Plrostr 3 Gsn23403  Plrostr 2 Gsn23403  Plrostr 5 Gc48893A 1A
Length Range
11.0-17.5 µm
Width Range
5.0-6.0 µm
Striae in 10 µm
11-13

Planothidium biporomum

(M.H.Hohn and Hellerman) Lange-Bert. 1999

Planothidium bipororum LM3 Planothidium bipororum LM1 Planothidium bipororum LM4
Length Range
12-25 µm
Width Range
5.4-7.0 µm
Striae in 10 µm
12-15