taxonID	type	description	language	source
721687E2087A17654BB7489B9DEAFA99.taxon	description	Similarly, the presence of open girdle bands in W. angusta excludes it from belonging to the monospecific genus Tibetiella, that closely resembles Ulnaria except for the presence of 2 – 5 rimoportulae on each apex (Li et al. 2010).	en	Rioual, Patrick, Flower, Roger J., Chu, Guoqiang, Lu, Yanbin, Zhang, Zhongyan, Zhu, Bingqi, Yang, Xiaoping (2017): Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with a discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushforth. Phytotaxa 329 (1): 28-50, DOI: 10.11646/phytotaxa.329.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.329.1.2
721687E2087A177B4BB74F97995EF9B9.taxon	description	i) The absence of spines and colonial formation: Not all Fragilaria species form colonies and bear spines; there are numerous examples such as Fragilaria pennsylvanica Morales (Morales 2003 a), F. pectinalis (O. F. Müller) Lyngbye (1819: 185) as illustrated in Wetzel & Ector (2015), F. candidagilae Almeida, C. Delgado, Novais & S. Blanco (in Delgado et al. 2015: 4), F. boreomongolica Kulikovskiy, Lange-Bertalot, Witkowski & Dorofeyuk (Kulikovskiy et al. 2010: 36). In their comprehensive revision of the needle-shaped group of fragilarioid diatoms, Lange-Bertalot & Ulrich (2014) also reported that several of the long, needle-like Fragilaria are spineless and have a solitary life-form including F. perdelicatissima Lange-Bertalot & Van de Vijver in Lange-Bertalot & Ulrich (2014: 19), F. saxoplanctonica Lange-Bertalot & Ulrich (2014: 30), Fragilaria aquaplus Lange-Bertalot & Ulrich (2014: 32) and Fragilaria gracilis Østrup (1910: 190). More generally, within the Fragilariaceae the presence or absence of spines is not a stable character at the genus level. For example, in Stauroforma Flower, Jones & Round (1996: 53), the spinose species Stauroforma exiguiformis 1 Here the nomenclature is complicated as species in the genus Synedra, as understood by Round et al. (1990) are now placed in Ulnaria. This is a nomenclatural act not a taxonomic one (Williams 2011). Flower, Jones & Round (1996: 53) can co-occur with the non-spinose species Stauroforma inermis Flower, Jones & Round (1996: 54) (Flower et al. 1996). Species within Pseudostaurosira D. M. Williams & Round (1988: 276) generally possess spines but exceptions exist such as Pseudostaurosira parasitica (W. Smith) Morales (2003 b: 287). Another example was given by Flower (2005) who distinguished Pseudostaurosira microstriata var. spinosa Flower (2005: 65) from the non-spinose nominal variety, Pseudostaurosira microstriata (Marciniak) Flower (2005: 65). Conversely, while species in Ulnaria are typically spineless, Ulnaria ungeriana (A. Grunow) Compère (2001: 100) have welldeveloped linking spines (Williams 1986, Siver et al. 2006). Even at the species level, the presence or absence of spines is not always a good criterion for taxonomic separation. For example, Staurosira dimorpha Morales (2010: 103) can form two sympatric variants, one with spines the other spineless. Interestingly, for this latter species the lack of spines does not prevent formation of colonies (Morales et al. 2010). ii) A preference for saline versus freshwater To argue against the inclusion of their new species in the genus Fragilaria, Graeff et al. (2013) referred to Round et al. (1990) who stated that Fragilaria species are restricted to freshwater. This statement however, is not entirely correct as Fragilaria famelica (Kützing) Lange-Bertalot (1980: 749) is commonly reported from marine coasts (Witkowski et al. 2000) and saline springs (Wojtal 2013). Graeff et al. (2013) described Williamsella angusta from the main basin and the surrounding marsh of Blue Lake, Utah. There, the salinity varies from 5.5 ppt in the lake to 13.4 ppt in the marshes (see Table 1 in Graeff et al. 2013). From these values, Graeff et al. (2013) deduced that their new species was restricted to saline waters. For the taxon we found in the Badain Jaran lakes however, our data (Fig. 76) suggest that it optimally grows in subsaline conditions, i. e. in a range of salinity of 0.5 – 3 ppt following the classification proposed by Hammer et al. (1983). The three lakes in which this fragilarioid diatom is most abundant have a salinity ranging between 1.3 and 2.0 ppt, although it was also found (0.2 %) in one lake with much higher salinity (30.3 ppt). iii) The external coverings of the areolae In their description of Fragilaria, Round et al. (1990) wrote that the areolae of this genus have delicate, often disc-like, cribra (as illustrated in their fig. g, p. 347). A structure very similar to the one observed in W. angusta exists in Fragilaria longifusiformis P. Siver, E. Morales, B. Van de Vijver, M. Smits, P. B. Hamilton & H. Lange-Bertalot (2006: 185), a species described from the south-eastern USA (Hains & Sebring, 1981) but also reported in Europe (Siver et al. 2006) and in Brazil (Ludwig et al. 2015). Siver et al. (2006) went on to argue that the presence of these areolae coverings they called disc-like vola, was one of the important characters for attributing F. longifusiformis to the genus Fragilaria (instead of Synedra, i. e. Ulnaria). Recently, Lange-Bertalot and Ulrich (2014) distinguished the subspecies F. longifusiformis ssp. eurofusiformis Lange-Bertalot and Ulrich (2014: 37). SEM images of this subspecies indicate that external coverings of the areolae can also be present in this taxon (plate 18, fig. 3) but are often dissolved (plate 18, figs 6 – 8). External coverings of the areolae can be observed in other needle-like Fragilaria species such as F. tenera (W. Smith) Lange-Bertalot (1980: 746) as illustrated in Lange-Bertalot and Ulrich (2014, plate 3, figs 3 – 6) and in Almeida et al. (2016, figs 15 – 17), F. neotropica P. D. Almeida, E. Morales & C. E. Wetzel (2016: 171) (figs 43, 47, 49 in Almeida et al. 2016). Note that Almeida et al. (2016) used the term rotae when referring to these structures.	en	Rioual, Patrick, Flower, Roger J., Chu, Guoqiang, Lu, Yanbin, Zhang, Zhongyan, Zhu, Bingqi, Yang, Xiaoping (2017): Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with a discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushforth. Phytotaxa 329 (1): 28-50, DOI: 10.11646/phytotaxa.329.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.329.1.2
721687E2087A177B4BB74F97995EF9B9.taxon	description	In summary, it would appear that the disc-like external coverings of the areolae, usually referred as volae or rotae, seem to be a common feature of Fragilaria species. It is likely that difficulty concerning assessing the presence or absence of volae or rotae in some species is due to dissolution either in the field or as an artifact of the cleaning method as suggested by our observations (contrast Figs 42 – 44 taken from cleaned material derived from surface sediment samples with Figs 45 – 47 taken from untreated material observed on the glass fiber filters used for the chemical analyses of water samples). Molecular studies on Fragilariaceae also suggest that the various types of covering over the areolae do not correspond with monophyletic clades (Medlin et al., 2008, 2012). In addition to the three characters discussed above, Al-Handal et al. (2016, see their Table 1) listed the presence of four plate-like plastids in Williamsella as another feature that differentiate this genus from the two plate-like plastids generally reported for the other Fragilarioid genera such as Ulnaria and Fragilaria. We found the same number and distribution of plastids in the Badain Jaran population (see Figs 1 ‒ 5) as the one shown by Al-Handal et al. (2016, Fig 7) for W. iraqiensis and this suggests that the two taxa are closely related. It is, however, not strictly correct that all Fragilaria species have two plate-like plastids as other configurations have been reported like in Fragilaria longifusiformis ssp. eurofusiformis Lange-Berlatot & Ulrich, which has undivided chloroplasts (Lange-Bertalot & Ulrich 2014, plate 17, figs 5 ‒ 7) and in F. spectra, which has numerous and elongate plastids (Almeida et al. 2016, figs 54, 55). In addition, the number and position of the plastids has not been reported for a majority of taxa currently considered to belong to Fragilaria. Therefore, while this character may be useful for the purpose of distinguishing species, it may not be appropriate at the generic level, at least until a more systematic study of the issue is carried out. From the above, we conclude that erecting the genus Williamsella on the basis of the three characters presented in Graeff et al. (2013), i. e. colonial formation, habitat and areolae coverings and the additional character of the number of plastids (Al-Handal et al. 2016), cannot be justified using these criteria. In addition, the structure of the cingulum (composed of several open copulae with a single row of areolae present along the advalvar edge) conforms to the description given for Fragilaria in Round et al. (1990). One option is to emend the definition of both Fragilaria and Williamsella another is that W. angusta and W. iraqiensis should be re-assigned to the genus Fragilaria as it is currently defined. Based on the above, we propose the second option:	en	Rioual, Patrick, Flower, Roger J., Chu, Guoqiang, Lu, Yanbin, Zhang, Zhongyan, Zhu, Bingqi, Yang, Xiaoping (2017): Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with a discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushforth. Phytotaxa 329 (1): 28-50, DOI: 10.11646/phytotaxa.329.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.329.1.2
721687E20865177A4BB74B739BD8F901.taxon	materials_examined	Type: – CHINA. Inner Mongolia, Shaobai Jilin, 39 ° 34 ’ 04 N 102 ° 14 ’ 78 E, 1204 m a. s. l, surface sediment sample collected by P. Rioual in June 2007 (holotype IGGDC!, designated here, individual from slide SHAO-ss 07, illustrated in Fig. 12, located using England Finder K 35 / 4; Isotype BM!, slide 101 / 801, designated here, Natural History Museum, London, United Kingdom).	en	Rioual, Patrick, Flower, Roger J., Chu, Guoqiang, Lu, Yanbin, Zhang, Zhongyan, Zhu, Bingqi, Yang, Xiaoping (2017): Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with a discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushforth. Phytotaxa 329 (1): 28-50, DOI: 10.11646/phytotaxa.329.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.329.1.2
721687E20865177A4BB74B739BD8F901.taxon	etymology	Etymology: — The species epithet refers to springs: crenophile is an organism preferring spring environment; the variety epithet refers to China. Habitat and distributions in Asia and North America Although the analysis of epiphyton samples suggests that F. crenophila var. sinensis is epiphytic, we cannot exclude that it can survive in the plankton as it was also present in the water samples collected from these lakes as shown by the presence of numerous whole cells (Figs 45, 46) found on the surface of the filters observed under the SEM. It is also unclear what is the habitat (planktonic or epiphytic) of the nominate variety of F. crenophila (= W. angusta) as Graeff et al. (2013) only mentioned that this species was found in the main basin of Blue Lake (max. depth = 18 m) and in the surrounding marshes. The response curves for F. crenophila var. sinensis along the salinity and TP gradients in lakes of the Badain Jaran Desert are shown in Fig. 76. The highest abundances of F. crenophila var. sinensis were observed in subsaline and mesotrophic lakes. In North America, together with the occurrence of F. crenophila in Blue Lake, Utah, a very similar taxon was identified as Fragilaria cf. tenera by Cumming et al. (1995: 89, pl. 8, figs 8 – 9) in subsaline lakes of British Columbia (Canada). In Lange-Bertalot (1993) valves identified as Fragilaria aff. famelica (Kützing) Lange-Bertalot (pl. 12, figs 12 – 14), from the Nine Mile pond in the Everglades (Florida, USA), may also belong to this taxon, especially as it was found in association with Fragilaria synegrotesca Lange-Bertalot (1993: 49), a taxon also found in Blue Lake. Graeff et al. (2013) seem to have overlooked the existence of F. synegrotesca however, as they described the Blue Lake populations as a new species U. toolensis instead of a simple re-combination within the genus Ulnaria. The Everglades specimens, however, have narrower valves (1.5 – 1.9 μm) than F. crenophila or F. crenophila var. sinensis and may represent yet another species or variety. Slate & Stevenson (2007) found the same taxon (see their figs 25, 78) in their study on the diatom flora of the Everglades (although they called it Fragilaria cf. tenera instead of Fragilaria aff. famelica) where it was especially common in un-enriched conditions with an estimated TP optimum of 14 μm ± 13 μg. L- 1. Their results were in agreement with those of Lange-Bertalot (1993) who reported this taxon in oligotrophic to mesotrophic waters not only from Florida but also from Jamaica, Mexico and Central America. Unfortunately, salinity was not mentioned in these two studies. The geographic distribution of Fragilaria crenophila and its variety sinensis could therefore indicate a widespread or disjunct species dispersal pattern that includes North America and Eastern Asia. Similar trans-Pacific distribution patterns have been reported for gomphonemoid taxa (Kociolek et al. 2013, You et al. 2013), for the araphid genus Tetracyclus (Williams 1996; Williams and Reid 2006; Williams 2009) and for a few other taxa belonging to the genera Cymbella, Frustulia, Navicula, Neidium, and Synedra (Potapova 2014).	en	Rioual, Patrick, Flower, Roger J., Chu, Guoqiang, Lu, Yanbin, Zhang, Zhongyan, Zhu, Bingqi, Yang, Xiaoping (2017): Observations on a fragilarioid diatom found in inter-dune lakes of the Badain Jaran Desert (Inner Mongolia, China), with a discussion on the newly erected genus Williamsella Graeff, Kociolek & Rushforth. Phytotaxa 329 (1): 28-50, DOI: 10.11646/phytotaxa.329.1.2, URL: http://dx.doi.org/10.11646/phytotaxa.329.1.2
