Correction

Figures & data

Table 4. Morphological characters of C. olympicus compared with two similar chain-forming species: C. tenuissimus (this study) and C. wighamii (Bosak et al., 2015).

Morphological characters	C. olympicus	C. tenuissimus	C. wighamii
Apical axis range (μm)	3.4-5.2 (morph.1), 8.0-10.5 (morph.2)	2.9-6.0	14-26
Life form	Solitary or short-medium size chains	Solitary or short-medium size chains	Usually short chains
Frustules:
Valve shape	Elliptical	Elliptical	Elliptical
Valve margin	With moderate hyaline rim	With high or low hyaline rim	With high hyaline rim
Mantle	Low	Low	Low
Chloroplast	One	One	One
Aperture	Narrowly lanceolate	Narrowly lanceolate to elliptical	Slit shaped and very narrow
Setae:
Fusion	At the chain edge	At the chain edge	At the chain edge
Basal part	No	No	No
Divergence from chain axis (Terminal)	Almost at an angle of 45^o	In general, at an angle of almost 45^o, but it can be variable	U- or V- shaped
Divergence from chain axis (Intercalary)	Perpendicular or slightly oriented towards one end of the chain	Generally, at an angle of almost 45^o in the proximal part and perpendicular in the distal part	Variable
Divergence with respect to apical axis	Brunel group II	Brunel group II	Brunel group III (sometimes II)
Cross section	Circular	Circular	Circular
Fine structure and ornamentation	Slightly twisted of few rows of small rectangular poroids and some spines arranged in spiral	Strongly twisted of many rows of small rectangular poroids and several spines arranged in spiral	Longitudinal filaments arranged is spiral interconnected by very short transverse bars forming a spiral row of minute poroids. Helicoidal pattern of spines
Number of poroids in 1 m	16.7 ± 1.1	26.9 ± 1.7	16 (?)
Rimoportula:	Absent	Only in terminal valves	Absent
Number		One
Location		Centrally
Shape		Slit
Resting spores:	Yes	Not observed	Yes
Location	Toward one end of the cell
Primary valve	Vaulted with short to medium size spines		Valve covered with spines
Secondary valve	Smaller, rounded and smooth		Shaped as a truncated cone

Fig. 45. LSU rDNA phylogenetic tree including sequences of some Chaetoceros representatives of interest and sequences obtained in this study (in bold). Sequences of Bacteriastrum species were used as outgroup. Statistical support shown in nodes corresponds to boostrap values (%) and Bayesian posterior probability. Only values >70% and 0.95 respectively are shown and black dots represent maximum statistical support. The different phylogenetic clusters were labelled according to morphological sections proposed in De Luca et al. (2019a). N.A. = species not assigned to any existing section. *C. tenuissimus after this work, see Discussion.