taxonID	type	description	language	source
03A087D9E72CFF9E12D0723AFAC0F8E4.taxon	materials_examined	Lectotype & Epitype (designated in Tuji & Williams 2006, p. 198): — Lectotype: figure 4 in O. F. Müller (1788) Nov. Acta Acad. Sci. Imp. Petropol. 3: 91; Epitype: an individual from slide BM 101152 in BM! (located at England finder L 33 - 3: Fig. 4 B in Tuji & Williams 2006), “ New river near Hornsey, March 5, 1802 ”. Type locality: — DENMARK, In palustribus Hauniensibus [in swamps near Copenhagen]. Material examined: — UNITED KINGDOM, Dillwyn’s original packet labelled “ New river near. Hornsey, Mar 5 1802 ” (BM 101152 - 3, slide BR- 4891); GERMANY, Gohlis (Leipzig), aus ein Gräben in Gohlis, Rabenhorst exsiccata sample n ° 2143 (BR- 4892).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72CFF9E12D0723AFAC0F8E4.taxon	description	Light microscopy (Figs 1 – 18): — Frustules solitary or in pairs, rectangular in girdle view (Fig. 1). Valves linear to rarely narrowly lanceolate with almost straight to rarely weakly convex margins. Apices distinctly protracted, subcapitate to rostrate. Valve dimensions (n = 20): valve length 25 – 40 µm, width 4.0 µm. Sternum narrow throughout its entire length, only slightly widening near the central area. Central area large, occasionally buttressed, either unilateral with large hyaline zone on one side and slightly shortened striae on the opposite side, or forming a transapical fascia. Ghost striae weakly discernible in LM (Figs 3, 5, 14). Striae almost entirely parallel throughout the entire valve, alternating, 15 – 17 in 10 µm. Areolae not discernible in LM. Scanning electron microscopy (Figs 19 – 24): — Girdle composed of several open, perforated bands (Fig. 19). Striae on the mantle composed of only a few small areolae continuing with a shallow slit (Fig. 19). Marginal spines absent to very rudimentary (Figs 21 & 22), usually reduced to small papilla-like siliceous outgrowths (Fig. 22, small arrows). Striae uniseriate, composed of very broad virgae (Figs 20 & 21) and series of areolae in depressed grooves (Figs 21 & 22). Ghost striae in the central area visible as shallow grooves (Fig. 22). Raised ridges present on the virgae. Areolae small, rounded (Fig. 21), covered by individual cribra. Large rimmed rimoportula present at one apex on the sternum. Rimoportula located on the last stria, replacing some of the areolae (Figs 20 & 21). Apical porefield of the ocellulimbus type, very large, composed of five long rows of small pores, located on the mantle covering the entire apex mantle (Fig. 21). Internally, rimoportula large, transverse (Figs 23 & 24). Virgae broad, raised (Fig. 23).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72CFF9E12D0723AFAC0F8E4.taxon	biology_ecology	Ecology and associated diatom flora: — The Dillwyn sample is dominated by a large Eunotia species forming long, ribbon-like colonies that was originally identified as Eunotia pectinalis (Kützing) Rabenhorst. Tuji & Williams (2005) examined original Kützing material from Jever and reported that since the type of Himantidium pectinale did not produce colonies, it is unclear how the Eunotia species in Dillwyn’s material should be identified. Other species in the sample include Fragilaria radians (Kützing 1844: 64) D. M. Williams & Round (1988: 269), Melosira varians C. Agardh (1827: 628), Tabularia cf. fasciculata (C. Agardh 1812: 35) D. M. Williams & Round (1986: 326) and an at present unidentified Ulnaria species. Based on this species composition it is, however, not possible to determine the ecological conditions of the type sample. The Rabenhorst sample 2143 from Leipzig is almost entirely dominated by F. pectinalis. Several other species occur in much lower numbers: Gomphonema parvulum (Kützing 1844: 83) Kützing (1849: 65), Fragilaria campyla (Hilse in Rabenhorst 1861: no. 1024) Van de Vijver et al. (in Van de Vijver et al. 2022: 97), Surirella terricola Lange-Bertalot & E. Alles (in Lange-Bertalot & Metzeltin 1996: 107), Planothidium lanceolatum (Brébisson ex Kützing 1846: 247) Lange-Bertalot (1999: 287) and Nitzschia palea (Kützing 1844: 63) W. Smith (1856: 89). These species point to more eutrophic, neutral to weakly alkaline conditions (Lange-Bertalot et al. 2017).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72CFF9E12D0723AFAC0F8E4.taxon	discussion	Taxonomic remarks: — The second investigated population in Rabenhorst sample 2143 (Gohlis near Leipzig), was initially identified as Synedra vaucheriae (Kützing) Kützing (1844: 65). The population spans a larger length range with the smallest observed valves being on 12 µm long. The apices are a little bit more elongated than in the epitype population. Nevertheless, we consider these differences insufficient to split both taxa as separate species.	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72AFF9C12D071EFFB34FC3F.taxon	description	Registration: http: // phycobank. org / 105483	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72AFF9C12D071EFFB34FC3F.taxon	materials_examined	Lectotype & Epitype (designated in Tuji & Williams 2008, p. 139): — Lectotype: Grunow in Van Heurck (1881): PI. 40, Fig. 26 b; Epitype: An individual from slide 2657 a with the description of Arnott 507 in Grunow collection in W. Material examined: — UNITED KINGDOM, Haverfordwest, Wales, Grunow sample 2657, leg; Okeden, W 2011 - 0002610, new slide made at Meise Botanic Garden based on original Grunow material (BR- 4893)	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72AFF9C12D071EFFB34FC3F.taxon	description	Light microscopy (Figs 63 – 101): — Frustules solitary or in pairs, rectangular in girdle view (Fig. 63). Valves narrowly lanceolate with weakly (longer valves) to clearly (smaller valves) convex margins. Apices distinctly protracted, clearly capitate. Valve dimensions (n = 40): valve length 14 – 30 µm, width 4.0 – 4.5 µm. Sternum very narrow throughout its entire length, only slightly widening near the central area. Central area very large, buttressed, shallowly depressed, clearly unilateral, with large hyaline zone on one side and almost not shortened striae on the opposite side. Ghost striae not discernible in LM. Striae parallel to very weakly radiate throughout the entire valve, alternating, 14 – 17 in 10 µm. Areolae not discernible in LM. Scanning electron microscopy (Figs 102 – 104): — Marginal spines absent (Fig. 102). Striae uniseriate, composed of very broad, raised virgae compared to the small vimines (Figs 102 & 103). Very low raised ridges present on the virgae. Areolae small, rounded (Fig. 103). One large, rimmed rimoportula at one apex, located on the last stria, replacing some of the areolae, close to the sternum (Figs 102 & 103, arrows). Apical porefield of the ocellulimbus type, relatively large, almost quadratic, composed of five rows of small pores, entirely located on the mantle (Fig. 103). Internally, rimoportula large, transverse (Fig. 104). Virgae broad, raised (Fig. 104).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72AFF9C12D071EFFB34FC3F.taxon	biology_ecology	Ecology and associated diatom flora: — Sample 2657 from Haverfordwest is almost entirely dominated by two species: Fragilaria striis-distantioribus and Meridion circulare (Greville 1822: 213) C. Agardh (1831: 40). Gomphonema parvulum and Planothidium lanceolatum were also found in the sample but in very low numbers. The dominance of M. circulare points to running waters with moderate electrolyte contents and usually lower nutrient levels (Lange-Bertalot et al. 2017). The presence of G. parvulum and P. lanceolatum may point to a slightly higher nutrient level.	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E72AFF9C12D071EFFB34FC3F.taxon	discussion	Nomenclatural note: — The taxon under discussion was described by Grunow in Van Heurck (1881, plate XL [40], figs 26 B. C.) and published as “ S. CAPITELLATA GRUN. FORMA STRIIS DISTANTIORIBUS. | 15 à 17 stries en 0,01 mm. ” The question, if Grunow described an unnamed forma with image and measurements and a short diagnosis “ striis distantioribus ” or a forma named ‘ stiis distantioribus’ with image and measurements was answered by Tuji & Williams (2008: 139) by using ‘ striis distantioribus’ as the epithet, hyphenated according to the ICN (see Turland et al. 2025 60.12 a 2 and b 1). This procedure is accepted here and the name used as the basionym.	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E728FF9C12D075D8FC22F852.taxon	description	Light microscopy (Figs 105 – 145): Frustules solitary or in pairs, rectangular in girdle view (Fig. 105). Valves linear-lanceolate with usually slightly convex margins throughout the entire cell diminution series. Smaller valves with more distinctly convex margins (Figs 141 – 145). Apices protracted, rostrate to subcapitate, broadly rounded. Valve dimensions (n = 50): valve length 15 – 25 µm, width 3.0 – 4.0 µm. Sternum narrow throughout its entire length, only weakly widening near the central area. Central area very large, buttressed, shallowly depressed, in part of the population unilateral, with large hyaline zone on one side and shortened striae on the opposite side. Other part of the population having large, fascia-like central area (e. g. Fig. 136). Ghost striae rarely discernible in LM (Figs 115, 136). Striae usually parallel to rarely very weakly radiate throughout the entire valve, alternating, 16 – 17 in 10 µm. Areolae not discernible in LM. Scanning electron microscopy (Figs 146 – 149): Marginal spines absent (Fig. 146). Very large mantle plaques present at the mantle margin (Fig. 148, arrow). Striae uniseriate, composed of very broad, raised virgae compared to the small vimines (Figs 146 – 148). Areolae small, rounded to very slightly apically elongated (Figs 146 – 147). One small, rimmed rimoportula present at one apex, located on the last stria, replacing some of the areolae, close to the axial area (Fig. 147). Apical pore field of the ocellulimbus type, relatively large, composed of six rows of small rimmed pores, entirely located on the mantle (Fig. 147). Internally, rimoportula large, oblique (Fig. 149). Virgae clearly raised (Fig. 149).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E728FF9C12D075D8FC22F852.taxon	materials_examined	Type: — FRANCE, Beaume River at Rosière, coll. date 18 / 05 / 2011, leg. M. - Y. Bey; (Holotype slide: BR- 4894, Fig. 111 represents the holotype). Registration: — http: // phycobank. org / 105484	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E728FF9C12D075D8FC22F852.taxon	etymology	Etymology: — The new species is named in honour of our late friend and colleague Luc Ector († 2022).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
03A087D9E728FF9C12D075D8FC22F852.taxon	biology_ecology	Ecology: — Wetzel & Ector (2015) reported the presence of the new species (as F. pectinalis) in several French rivers characterised by hard water and a relatively good water quality. The holotype sample was collected from the small (length 44 km) river Beaume in the Department of the Ardèche. In 2011 (the year of sampling) the river had a pH ranging between 7.6 – 8.4, a conductivity ranging between 38 and 499 µS / cm with the higher values in spring and summer and the lower values only in the winter months, and very low nutrient values of nitrate and phosphate. In Wetzel & Ector (2015, p. 282) a list of dominant taxa in the sample is added mainly composed of several Achnanthidium and Fragilaria species. According to Bey & Ector (2013, p. 228) the species is observed in the Rhône-Alpes region in watercourses of good quality. The species is very rare in the Rhône-Alpes region: observed only on the lower Drôme, the Romanche, the Baume, and the Eygues rivers (Wetzel et al. 2015).	en	Vijver, Bart Van De, Kusber, Wolf-Henning, Wetzel, Carlos E., Williams, David M. (2025): A revision of the Fragilaria pectinalis-complex in Europe (Bacillariophyceae, Fragilariaceae) with the description of a new species. Phytotaxa 726 (2): 61-73, DOI: 10.11646/phytotaxa.726.2.1, URL: https://doi.org/10.11646/phytotaxa.726.2.1
