taxonID	type	description	language	source
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	Description: — The raphe is filiform and continuous from the central area to the end of the row of areolae. Lateral depressions flank proximal raphe ends. Distal raphe ends appear to lack lateral depressions. Axial area is lanceolate. Valves are naviculoid tapering to rounded ends. There is a subtile construction near the ends of the valves. The striae are continuous through the length of the valve and flair in the center leaving a circular central area. We were not able to view specimens with SEM in girdle view nor valve interior. Collection Information: — ICELAND. Scrape and a bryophyte and lichen squeeze, collected from a rock outcrop in the Hengill watershed (~ N 64 3 23.0, W 21 17 1.0, WW 5 Table 1), P. C. Furey, 13 July 2013. (Cleaned material – GCAC 4212, and representative specimen circled on slide GCAC 4212 deposited in the diatom collection at Georgia College and State University, USA. Here illustrated as Fig. 8 N).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	discussion	Comments: — This unidentified taxon should be compared to Humidophila arctica (Lange-Bertalot et Genkel 1999: 40) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot et Kopalová (2014: 357) but differs in the valves being more naviculoid. Both taxa have areolae that are interrupted in the central area, but frustules of H. arctica have broadly rounded ends (Lange-Bertalot & Genkal 1999, Tafel 21 Figs 8 – 14) in contrast to the more tapered ends of Humidophila sp. 1. More information, especially around interal and girdle views are needed to establish details key to a new taxon description, therefore, we currently designated this taxon as unidentified Humidophila sp. 1 until more information can be gathered. Specimens were generally absent from most samples, but occasionally contributed <5 % to the relative abundance at sites in Hengill and Þingvellir rift valley, though at WW 5 relative abundance reached 5.5 % (Table 2). Humidophila eldfjallii sp. nov. (LM = Fig. 8 E – H; SEM = Fig. 8 A – D)	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	Description: — Valves strongly triundulate, length 12.2 – 14.9 μm, width middle 3.0 – 3.6 μm, width apices 3.0 – 3.6 μm; 33.0 – 35.4 striae in 10 μm (for n = 5 LM, n = 5 SEM). The raphe is filiform with distal ends bending slightly in opposite directions. The axial area is lanceolate leading to a round central area. Both distal and proximal raphe ends lack any lateral depressions. exceptionally sparse (<50 valves counted) are not included here). Listed alphabetically.	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	materials_examined	Holotype: — ICELAND. Surface scrape and a bryophyte and lichen squeeze collected from a rock face located river right of the River Hengladalsá in the Hengill watershed (~ N 64 3 23.0, W 21 17 1.0, WW 38 Table 1), P. C. Furey, 14 July 2013. Circled specimen on slide GCAC 4213, deposited in the diatom collection at Georgia College and State University Natural History Museum, USA. Here illustrated as Fig. 8 F). Type Material: — Cleaned type material deposited in the Georgia College and State University Natural History Museum, USA diatom collection. GCAC 4213.	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	etymology	Etymology: — This specific epithet refers to the Icelandic word for ‘ volcano’ – ‘ eldfjall’ (eldur – “ fire ”, and fjall – “ mountain ”) after the volcanic rock it was collected from in the Hengill watershed; also the location of the Hengill volcano.	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	discussion	Comments: — The strongly triundulate valves of H. eldfjallii are different than most species in this genus. Humidophila eldfjallii differs from H. costei (Le Cohu et Van de Vijver 2002: 122) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot et Kopalová (2014: 357) and H. ingeae (Van de Vijver in Van de Vijver et al. 2002: 338) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot et Kopalová (2014: 358) by valves that are much more strongly triundulate with bulbous valve ends, whereas H. costei and H. ingeae have more subtly undulated valves. Additionally, H. ingeae displays marginal aereola on the valve face while they are on the mantle in H. eldfjllii. Specimens occurred at> 5 – 10 % (WW 38) and> 10 – 20 % (WW 54) relative abundance in Hengill, but otherwise occurred at low relative abundances in Hengill and the Þingvellir rift valley (Table 2).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	Valve dimensions (for n = 9 LM, n = 3 SEM) length 7.2 – 9.1 μm, width middle 2.0 – 3.1, width apices 2.0 – 3.1; 34.0 – 34.9 striae in 10 μm. T-shaped depression of the proximal raphe ends absent. This species was earlier considered to be a variety of Navicula contenta Grunow in Van Heurck (1885: 109), and was moved (as a variety) to Diadesmis contenta (Grunow 1885: 109) D. G. Mann in Round, R. M. Crawford & D. G. Mann (1990: 666), but SEM views in this study show that it lacks the T-shaped depressions at the proximal raphe ends, a characteristic of D. contenta. Diadesmis arcuata (Heiden in Heiden et Kolbe 1928: 628) Lange-Bertalot in Moser, Lange-Bertalot et Metzeltin (1998: 136) lacks this depression, and therefore we consider this species to be more closely related to D. arcuata than to D. contenta. There is currently some question about the validity of D. arcuata, as it has a basionym that is illegitimate (Navicula arcuata Heiden in Heiden et Kolbe 1928: 628) because it was a later synonym of Navicula arcuata Pantocsek (1892: 64 (1905), pl. 6: fig. 97). Lange-Bertalot correctly considered the name arcuata available for a species in Diadesmis, but he incorrectly made a new combination with Heiden’s illegitimate taxon as basionym when he should have simply used arcuata as a replacement name (Moser et al. 1998). Lowe et al. (2014) made the same error in their new combination. Given that the recognition of subspecific taxa in diatoms is a less widespread practice than in prior decades, and the possible incorrectness of the recent combinations with Navicula arcuata, we decided to recognize this taxon at the species level. Valves generally were absent or contributed <2 % to the relative abundance of samples from Hengill and Þingvellir rift valley, though relative abundance reached 7 % at one site in Hengill (WW 3; Table 2). Humidophila biceps (Grunow in Van Heurck 1880: expl. Pl. XIV, fig. 31 B) comb. nov. (LM = Fig. 7 C – E; SEM = Fig. 7 A – B). Basionym: Navicula trinodis var. biceps Grunow in Van Heurck 1880: expl. Pl. XIV, fig. 31 B Valve dimensions (for n = 14 LM, n = 4 SEM): length 10.0 – 14.5 μm, width middle 2.5 – 3.5 μm; 39.3 – 41.6 striae in 10 μm. Valves had a slight convex area in the middle. Short, comma – like depressions flanking the proximal raphe ends were similar to those shown in SEM micrographs in Veselá & Johansen (2009, as Diadesmis biceps fig. 199). This taxon is synonymous to D. biceps G. A. Arnott ex Cleve (1894: 132) nom. inval. and D. contenta var. biceps. Frustules occurred at low relative abundance at several sites in the Hengill watershed, but also reached higher relative abundances at sites in both Hengill and the Þingvellir rift valley, four of which were> 20 % relative abundance (Table 2).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	Humidophila gallica, consistently present in the Hengill and the Þingvellir rift valley, consistently occurred at relative abundances> 5 %, and at 5 sites> 20 % (Table 2). Humidophila gallica is a typical on mosses and ferns (as Diadesmis gallica; Roldán et Hernández – Mariné, 2009).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	Humidophila paracontenta, absent from Þingvellir rift valley, typically comprised <1 % of the relative abundance of samples from Hengill, but was the only taxon observed from a sparse sample at WW 21 (Table 3).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A69FF8FFF00537FFA37F7AE.taxon	description	counted) are not included here). Listed alphabetically. ...... continued on the next page ...... continued on the next page	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A7BFF8AFF005551FE4BFF7F.taxon	description	This taxon only occurred at a few sites in Hengill and Þingvellir rift valley, but at <5 % relative abundance (Table 3). The checklist of algae from Iceland (Hallgrímsson 2007) includes E. arctica. Lange-Bertalot et al. (2011) show images of specimens from Iceland (type locality), along with valves from Spitzbergen (Svalbard) with a similar, but slightly different morphology (see outline of inflated areas; plate 73, figs 9 – 15).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A7BFF8AFF005551FE4BFF7F.taxon	description	Valves of E. bidens were only observed at <1 % relative abundance in a bryophyte squeeze in the Þingvellir rift valley (WW 41; Table 2).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A7BFF8AFF005551FE4BFF7F.taxon	description	The valves from Iceland align best with valve measurements for E. bigibba described from other populations in Lange-Bertalot et al. (2011; length 20 – 43 μm, width inflated area 8 – 14 μm, striae 10 – 12 in 10 μm, areolae ca. 30 in 10 μm). The shorter, narrower valves with higher striae density contrast with those of E. sarek Berg (1939: 449) (Length 40 – 57 μm, width inflated area 14 – 23 μm, striae 7 – 10 in 10 μm; Lange-Bertalot et al. 2011). The narrower depression between the inflated areas sets valves apart from those of E. suecica Cleve (1895: 29).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A7BFF8AFF005551FE4BFF7F.taxon	description	(1996: 48) (LM = Fig. 6 A – E; SEM = Fig. 6 F – J) The valve morphology of E. curtagrunowii measured at length 21 – 28 μm, width 7 – 8.5 μm, 9.4 – 13.0 striae (middle) in 10 μm, 14.4 – 18.0 striae (ends) in 10 μm, and areolae 30 – 35 in 10 μm (for n = 10 LM, n = 4 SEM). Valve measurements and morphological descriptions conform to those reported in Lange-Bertalot & Metzeltin (1996) and Lange-Bertalot et al. (2011). In our specimens, a single rimoportula occurred just below the midpoint of the valve apex with a simple, round opening externally (Fig. 6 G) and a raised opening internally (Fig. 6 I). Note the patterning, and single enlarged areola along the external, ventral margin (Fig. 6 H), also shown in other SEM micrographs (Lange-Bertalot et al. 2011; plate 196, fig. 9 – 12, 13). The narrower valves distinguish specimens from Iceland from those of E. ewa Lange-Bertalot et Witkowski in Lange-Bertalot et al. (2011: 93) from Greenland (width 9.5 – 13 μm). The rectangular girdle view of valves from Iceland (Fig. 6 D, E) contrast with the parallelogram-like shape of the girdle view of a similar shaped taxon, E. parallelogramma Van de Vijver, M. de Haan et Lange-Bertalot (2014: 274), reported from Antarctica. Frustules occurred in association with bryophytes and lichen at 11 % relative abundance at WW 1, and in low densities other sites in Hengill and the Þingvellir rift valley (Table 2). Eunotia curtagrunowii is reported as E. praerupta var. muscicola Petersen (1928: 377) from terrestrial habitats in Iceland (Petersen 1928 a, Broady 1978) and included in the checklist of algae from Iceland (Hallgrímsson 2007). Eunotia cf. neofallax Nörpel-Schempp et Lange-Bertalot in Lange-Bertalot et al. (1996: 3) (LM = Fig. 4 Q – W) Valves observed measured at length 9.0 – 22.0 μm, width 1.7 – 2.5 μm, and 16 – 20 striae in 10 μm (for n = 9 LM). Valves showed a similar outline to those of E. neofallax Nörpel-Schempp et Lange-Bertalot, though stria density in our specimens was slightly denser and the presences of a spine on the apex could not be confirmed. Relative abundance occurred at> 10 % at one site in the Þingvellir rift valley and> 20 % at one site in Hengill (Table 2). Previous reports of E. neofallax from intermittently wet subaerial habits included those with melting snow (Bouchard et al. 2018).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A7BFF8AFF005551FE4BFF7F.taxon	description	Frustules occurred in association with bryophytes and lichen at low relative abundances (<5 %) in Hengill and the Þingvellir rift valley (Table 3). Lange-Bertalot et al. (2011) show specimens from a variety of aerophilous locations including the type population in Germany (see also Werum & Lange-Bertalot 2004, plate 7, figs 10 – 18) and the synonym from Iceland (as E. arctica var. simplex Hustedt 1937: 169), as well as Tara Mountains Poland, Southern Alps, Italy, Pyrenees, Andora.	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A79FF8BFF00522DFEF2FC0F.taxon	description	Specimens from Iceland fit into the Orthoseira roeseana complex due to the presence of carinoportulae, linking spines, and a fairly deep mantle (Round et al. 1990). The radiate striae and number of carinoportulae distinguish Orthoseira roeseana from O. johansenii Lowe et Kociolek in Lowe et al. (2013: 46) (Lowe et al. 2013). The absence of rimoportulae (slits) between carinoportulae contrasts with Orthoseira species where this feature occurs such as O. verleyenii Van de Vijver in Lowe et al. (2013: 41) from lava tubes in Île Amsterdam (Lowe et al. 2013), O. gremmenii Van de Vijver et Kopalová (2008: 108) from the small volcanic Gough Island, southern Atlantic Ocean (Van de Vijver & Kopalová, 2008), O. limnopolarensis Van de Vijver et Crawford (2014: 248) from a sediment core Livingston Island (South Shetland Islands, Antarctica) (Van de Vijver & Crawford 2014), and Orthoseira taxon 1 and 2 from Madagascar (Spaulding & Kociolek 1998). Valves occurred infrequently in general, but relative abundance occurred at 12 % (WW 20) in Hengill and at 2.6 % (WW 51) along Landmannaleið. Both sites contained some moss, a typical association for this genus (Roldán & Hernández-Mariné 2009). This taxon is also commonly reported from moist soils, wet walls, waterfall spray zones, and wet but not submerged habitats (Lowe et al. 2013).	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
2E2D5A4B2A76FF86FF3555FAFE07FD2F.taxon	description	Valves linear with parallel margins and broadly rounded, not protracted ends (length 65 – 72 μm, valve width 12 – 13 μm, 5 striae in 10 μm, for n = 5 LM). Axial area narrow, linear. Central area rounded more than ½ of the width of the valve, asymmetrical in the middle due to the shortening of some striae on one side and on the other no visible striae on valve face and central area reaching margin. Raphe moderately lateral, slightly arcuate. Proximal raphe ends deflected towards one side and curved, no visible central pores.	en	Furey, Paula C., Manoylov, Kalina M., Lowe, Rex L. (2020): New and interesting aerial diatom assemblages from southwestern Iceland. Phytotaxa 428 (3): 173-208, DOI: 10.11646/phytotaxa.428.3.2, URL: http://dx.doi.org/10.11646/phytotaxa.428.3.2
