Phytotaxa 231 (3): 260–270 www.mapress.com/phytotaxa/ Copyright © 2015 Magnolia Press
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PHYTOTAXA
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http://dx.doi.org/10.11646/phytotaxa.231.3.4
Two new Nitzschia species (Bacillariophyceae) from China, possessing a canalraphe-conopeum system BING LIU1,2, SAÚL BLANCO3 & BANGQIN HUANG2 College of Biology and Environmental Science, Jishou University, Jishou 416000, China. College of the Environment & Ecology, Xiamen University, Xiamen 361005, China. 3 Department of Biodiversity and Environmental Management, University of León, 24071 León, Spain. Current address: The Institute of the Environment, La Serna, 58, 24007 León, Spain. *Corresponding author (e-mail:
[email protected]) 1 2
Abstract Two new species in the diatom genus Nitzschia were found in the middle intertidal zone, Xiamen Bay, southern China. Both new taxa belong to the subgenus Nitzschia, as inferred from the presence of a canal-raphe-conopeum system. The valves of both new species are dorsiventral. In Nitzschia arierae sp. nov., the raphe system is positioned centrally, the conopea fuse to the valve face at supporting points, and the zone of valve face subtended by the conopeum has areolae. In Nitzschia gaoi sp. nov., the raphe system is centrally positioned or slightly eccentric, two large conopea extend out from near the raphe while two small conopea extend out from each transverse costa and cover the striae, most part of the zone of valve face subtended by the conopeum has no areolae, and there are two long produced rostrate apices that both arch toward the ventral side or one apex arches and the other is straight. Both new species are epipelic forms inhabiting the coastal environment. Key words: Benthic diatom, Nitzschia, intertidal mud-flats, nitzschioid symmetry, Xiamen Bay
Introduction Nitzschia Hassall (1845: 435) is a long-established and taxonomically difficult genus of raphid diatoms. Smith (1853) divided this large genus into six sections for the first time. Grunow (1862) further distinguished 11 unranked groups in this genus and later amended his own system (in Cleve & Grunow 1880) into 24 groups. Grunow’s system is still in use with some modifications (e.g. Mann 1986, Round et al. 1990). Despite Nitzschia taxa are commonly recorded in most diatom assemblages from fresh to brackish and marine waters (Denys & Lange-Bertalot 1998), the determination and delimitation of many taxa with overlapping diagnostic criteria still remain difficult and unclear, because of the lack of comprehensive descriptions of nomenclatural types and undescribed variability of diagnostic features that often overlap (Hlúbiková et al. 2009). Mann (1986) reviewed the infrageneric classification of Nitzschia and erected the subgenus Nitzschia, which possesses a suite of characters that, notably the presence of siliceous flaps on either side of the raphe system, are not found in other Nitzschia or Hantzschia species. Lobban & Mann (1987) examined Nitzschia martiana (C.A. Ag.) Van Heurck (1896: 406; basionym: Homoeocladia martiana C.A. Agardh 1827: 629) and transferred it into the section Spathulatae within the subgenus Nitzschia. Knattrup et al. (2007) gave a detailed description of Nitzschia sigmoidea (Nitzsch) W. Smith (1853: 38; basionym: Bacillaria sigmoidea Nitzsch 1817: 104) which is an important member in the subgenus Nitzschia. Furthermore, Mann & Trobajo (2014) added three new dorsiventral conopeum-bearing diatoms to the subgenus Nitzschia. Based on these previous references, it can be concluded that two important structures, canal raphe and conopeum, form a unique combination in the subgenus Nitzschia. This unique combination can be termed as the canal-raphe-conopeum system. Both new Nitzschia species analyzed in the present study possess this system. Here we describe these two new members of the subgenus Nitzschia and add two new examples for the canal-rapheconopeum system. Because China possesses an enormous coastline from north to south, there is a great potential to discover new diatom species in this littoral zone. Nevertheless, there are only few studies which presented new species in this area. 260
Accepted by Rafael Riosmena-Rodriguez: 7 Oct. 2015; published: 23 Oct. 2015
Two new species, Gyrosigma rostratum Liu, Williams & Huang in Liu et al. (2015a: 256) and Gyrosigma xiamenense Liu, Sterrenburg & Huang in Liu et al. (2015b: 261), have been recently described from Xiamen Bay, China. In this location we found two Nitzschia species both possessing the canal-raphe-conopeum system. However, they differ from all other described species within the subgenus Nitzschia and neither matches any other known described taxon. Thus we describe these as taxa new to Science, Nitzschia arierae and Nitzschia gaoi, discussing their taxonomic position within the genus and reporting their habitat and ecology.
Materials and methods Site description:—The study site (24°31′54″N, 118°20′16″E) is in the middle intertidal zone of Yangtang Village, Dadeng Island, Xiamen Bay, southern China. Xiamen Bay is located in the west of Taiwan Strait, between longitudes 117°40′ and 118°40′ E, latitudes 24°6′ and 24°40′ N. The tide of Xiamen Bay is a typical semidiurnal tide with a mean tidal range of 3.79 m and maximum range of 6.24 m (Lakhan 2003). The tidal range is meso-tidal according to Davies (1964). Sampling:—We arrived at the sampling site half an hour before the low tide time according to the tide forecast (http://www.tide-forecast.com/locations/Xiamen-China/tides/latest). At low tide, two sediment surface scrapes and three sediment (grain size) samples were collected at the middle intertidal zone. Surface sediment scrapes (5–6 mm deep) were placed in 10 mL test tubes and fixed with 70% ethanol. GPS coordinates and several water and sediment characteristics were recorded for the sampling site in the field. The salinity was measured using Salinity Refractometer (Model: MASTER-S/MillM, Atago U.S.A., Inc.) and pH value was measured using direct soil pH meter (Model: HI99121, HANNA instruments, U.S.A). Methods:—The samples were processed by boiling in nitric acid and rinsing three times with deionized water following the procedure described in Mann (1978). Permanent slides were prepared using Naphrax® mountant. The permanent slides were examined and photomicrographed using a Leica DM3000 light microscope (LM) and a Leica DFC425C camera. For each taxon, morphometric parameters were measured in 30 individuals. Sediment grain size samples were analyzed using a Mastersizer 2000 particle size analyzer in the Third Institute of Oceanography, State Oceanic Administration, China. Locations of holotype and isotype valves on the slides were determined by the method described in Sterrenburg et al. (2012). The holotype slide was deposited in the Herbarium of the Department of Biology of Jishou University, Hunan, People’s Republic of China (JIU), and an isotype slide is kept in the personal Liu collection at Jishou University, Hunan, People’s Republic of China. For scanning electron microscopic analyses, several drops of cleaned diatom material were air-dried on glass coverslips. The selected air-dried coverslips were attached to the stub using a double-sided adhesive conductive carbon tape and sputter-coated with gold. Samples were examined and photomicrographed using either LEO 1530 Scanning Electron Microscope at 10–20 kV in Xiamen University, China, or Sirion 200 Scanning Electron Microscope at 10–20 kV in Central South University, China. Morphological terminology follows Ross et al. (1979), Mann (1986), and Man & Trobajo (2014).
New species description Division: Bacillariophyta Class: Bacillariophyceae Order: Bacillariales Family: Bacillariaceae Genus: Nitzschia Subgenus: Nitzschia Nitzschia arierae Bing Liu, S. Blanco et B.Q. Huang, sp. nov. (Figs 1–22) Valves dorsiventral, 54–156 μm long, 6.5–10.9 μm broad. Canal raphe prominent, centrally positioned. Fibulae distinct, 5.0–7.5 in 10 μm. Conopea present on either side of the raphe, recognizable as two parallel lines. TWO NEW NITZSCHIA SPECIES FROM CHINA
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Type:—China. Fujian: Xiamen Bay, Dadeng Island, the middle intertidal zone of Yangtang Village, 24°31′54″ N, 118°20′16″ E, 0 m a.s.l., 15 July 2013, Bing Liu 20153G (holotype JIU! G201503, illustrated in Fig. 3, 8.9 mm south by 9.7 mm east from the benchmark cross on the slide; isotype CL! 201303, illustrated in Fig. 1, 5.0 mm south by 15.6 mm east from the benchmark cross on the slide).
FIGURES 1–7. Nitzschia arierae, sp. nov., LM. 1–7. Seven valves showing size reduction. 1. Photograph of isotype specimen, note the two rows of dark spots (six arrows) and the two parallel lines on either side of the raphe. 3. Photograph of holotype, note the centrally positioned raphe system. Scale bar = 10 μm for all figures.
Description:—LM: Valves dorsiventral, with a concave ventral margin, slightly tumid in the middle, and an arched and convex dorsal margin (Figs 1–7), 54–156 μm long, 6.5–10.9 μm broad (N=30). Valve outline constant, but very variable in length, and less so in width (Figs 1–7). Poles cuneate, ventrally bent. Striae not resolvable under LM. Canal raphe prominent, centrally positioned, lacking central raphe endings. Fibulae distinct and irregularly spaced, 5.0–7.5 in 10 μm. Interspaces of the fibulae rectangular to square. Two conopea present on either side of the raphe, recognizable as two parallel lines. A row of dark spots, which supports the conopeum, are placed on the margin of each parallel line from pole to pole (Fig. 1, six arrows). At poles, helictoglossae distinctly marked as dark dots.
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FIGURES 8–11. Nitzschia arierae, sp. nov., external views, SEM. 8. A whole valve, note the constant width of conopeum. 9. Apex, showing the apical pore field (wavy arrows), the hooked terminal fissure towards the dorsal side (arrowhead), and the supporting points (arrows). 10. Central area, note the supporting points (arrows). 11. Another apex, note the hooked terminal fissure towards the dorsal side (arrowhead) and the supporting points (arrows). Scale bars = 10 μm (Fig. 8), 1 μm (Figs 9–11).
FIGURES 12–16. Nitzschia arierae, sp. nov., internal views, SEM. 12. A whole valve, note the interspaces narrower towards the poles. 13. Apex, note the distinctive apical pore field and the poroids in the keel zone (two arrows). 14–16. Central areas, showing the subtended zone different from the uncovered zone (Fig. 14, double-head arrows), shortened striae (arrows), dichotomous striae (wavy arrows), and poroids present in the keel zone (Figs 14–15, arrowheads). Scale bars = 10 μm (Fig. 12), 1 μm (Figs 13–16).
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SEM: External views: Valve conopea extending out from the raphe canal on either side (Figs 8–11). Conopea slightly arched, attached to both the raphe sternum and the wall of the raphe canal, strutted by two rows of supporting points and the margins of the conopea not completely fused to the valve (Figs 8–11). Two rows of supporting points (appearing as dark spots in LM) irregularly spaced on both ventral and dorsal sides (Figs 9–11, arrows). Width of the conopeum constant except near each pole, where it becomes narrower (Figs 9, 11). At poles, conopeum fused to the valve face and two large rectangular openings into the space beneath each conopeum (Figs 9, 11). Apical pore field present (Fig. 9, wavy arrows). Striae uniseriate, 50–51 in 10 μm, formed by tiny round poroids. Raphe lacking central raphe endings; terminal fissures hooked towards the dorsal side ((Figs 9, 11, arrowheads).
FIGURES 17–22. Nitzschia arierae, sp. nov., canal-raphe-conopeum system, SEM. 17. External view of the apex, note that the conopea are fused into the valve (arrow). 18–19. External view of central area, note conopeal canal, raphe canal and supporting points. 20–22. Internal views, note keels and supporting marks. Abbreviations: c = conopeum, cc = conopeal canal, cv = zone of valve face subtended by conopeum, f = fibula, k = keel, r = raphe slit, rc = raphe canal, sm = supporting mark, v = uncovered zone of valve face. Scale bars = 1 μm (Figs 17–18, 20–22), 2 μm (Fig. 19).
Internal views: Raphe running continuously from pole to pole and subtended by bar-like fibulae (Figs 12–14). The interspaces between the fibulae become narrower transapically towards the poles than near the center of the valve (Fig. 264 • Phytotaxa 231 (3) © 2015 Magnolia Press
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12). Raphe always rising on a keel (Figs 13–14). Apical pore field distinctive and poroids in the keel zone present (Fig. 13, two arrows). The subtended zones markedly different from the uncovered zones (Fig. 14, double-head arrows). At the middle part of the dorsal side of the valve, one or two striae shortened (Figs 14–16, arrows) near a dichotomous stria (Figs 14–16, wavy arrows), and poroids in the raphe-sternum occur opposite to this dichotomous stria (Figs 14–15, arrowheads). Canal-raphe-conopeum system: Raphe slit centrally positioned (e.g. Figs 17, 20, r). Conopea themselves are not porous (Figs 17–18, c, rs). The supporting points are conspicuous (Fig. 19, arrows; Fig. 22, sm). The uncovered zones in valve faces are different from the zones subtended by conopea, which are arched inwards and present areolae (e.g. Figs 18, 20–22, v, cv). A keel (raphe canal wall) with areolae (Fig. 21, two arrows) supports both the conopeum and the raphe sternum (Figs 18, 20–22, k). Etymology:—From the Latin noun ariera (banana), referring to the valve outline just like a banana. Ecology:—In the sampling site of Yangtang Village, the sediment type (Wentworth scale) is classed as medium silt, salinity of water is 27 ± 1 ppt, pH is 7.98 ± 0.01, and water temperature is 28.1 ± 0.3 °C showing that N. arierae is epipelic and lives in the coastal environment.
FIGURES 23–29. Nitzschia gaoi, sp. nov., LM. 23–25. Three valves showing a slightly eccentric raphe system. 24. Photograph of holotype. 26. One valve showing a centrally positioned raphe system. 27–29. Three valves showing a slightly eccentric raphe system. 27. Photograph of isotype specimen. Scale bar = 10 μm for all figures.
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Observations:—Mann & Trobajo (2014) described three new dorsiventral species in the subgenus Nitzschia. Although N. arierae and these three species all possess the canal-raphe-conopeum system and dorsiventral valve outline, the former differs from the latter by the centrally positioned canal raphe. Except above four species, no other dorsiventral Nitzschia taxa belonging to the subgenus Nitzschia can be found in the literature. The epithet of Nitzschia arcuata Gregory in Greville (1859: 82) recalls a dorsiventral valve outline, but N. arcuata is curved only in girdle view and does not possess conopeum. The small individuals of N. arierae are similar to those of N. bacillariaeformis Hustedt (1922: 149), N. harderi Hustedt in Brendemühl (1949: 441), N. incrustans Grunow (1862: 566) or N. terricola Lund (1946: 100), all of them showing straight frustules along the whole life cycle. Nitzschia gaoi Bing Liu, S. Blanco et B.Q. Huang, sp. nov. (Figs 23–49) Synonym: Nitzschia sp. “(?) Als Nitzschia lorenziana in Cleve & Möller 209, Rovigno/Adria, evtl. Nitzschia behrei zuzuordnen” in Krammer & Lange-Bertalot (1988: fig 86, 5)
Valves dorsiventral, with long produced rostrate apices, 83–107 μm long, 3.8–5.7 μm broad. Canal raphe prominent and slightly eccentric or positioned along the central axis of the valve. Fibulae distinct, irregularly spaced, 8–11 in 10 μm in the middle, 8–13 in 10 μm at apices. Two conopea are present and recognizable as two parallel lines on either side of the raphe.
FIGURES 30–39. Nitzschia gaoi, sp. nov., external views, SEM. 30–31. Two complete valves, note the nitzschioid symmetry of the raphe system. 32–33. Apices, note the constant width of the conopeum. 34–35. Apices showing the apical pore fields and the hooked terminal fissures towards the dorsal side. 36. Intact central area, showing costae, conopea, and the fusing of costae with conopeal spines (arrowheads). 37. Eroded area showing small conopea occuring on each side of each costa, and a transverse row of areolae appearing in a girdle band. 38. Eroded area showing striae and areolae. 39. Broken central area, showing the canal-raphe-conopeum system (cc = conopeal canal). Scale bars = 10 μm (Figs 30–31), 1 μm (Figs 32–39).
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Type:—China. Fujian: Xiamen Bay, Dadeng Island, the middle intertidal zone of Yangtang Village, 24°31′54″ N, 118°20′16″ E, 0 m a.s.l., 15 July 2013, Bing Liu 20154G (holotype JIU! G201504, illustrated in Fig. 24, 2.2 mm south by 9.9 mm east from the benchmark cross on the slide; isotype CL! 201304, illustrated in Fig. 29, 5.5 mm south by 4.0 mm east from the benchmark cross on the slide).
Description:—LM: Valves dorsiventral, with a ventral margin straight in the middle but concave to almost straight at apices, which are long produced, rostrate, and an arched and convex dorsal margin (Figs 23–29), 83–107 μm long, 3.8–5.7 μm broad (N=30). The two long produced apices are slightly arched toward the ventral side (Figs 24, 26, 28), or only one apex arched and the other straight (Figs 23, 25, 27, 29). Canal raphe prominent and slightly eccentric (Figs 23–25, 27–29), or positioned along the central axis of the valve (Fig. 26). Fibulae distinct, irregularly spaced, parallel to the transapical axis, 8–11 in 10 μm in the middle, 8–13 in 10 μm at apices. Interspaces of the fibulae rectangular or round. Two conopea are present and recognizable as two parallel lines on either side of the raphe (Figs 23–29). Transapical striae are not visible with light microscopy. SEM: External views: Valve dorsiventral with long produced, rostrate apices arched towards the ventral side, raphe system present on both sides of the valves (nitzschioid symmetry, Figs 30–31). Conopea distinctive from pole to pole, constant in width (Figs 30–33). At the poles, the conopeum is fused to the valve face and apical pore fields are present (Figs 34–35). Transapical costae conspicuous in intact valves, 40 in 10 μm, connected through few short siliceous structures (Fig. 36). Some spines extend from the conopea, fusing into certain transapical costae (Fig. 36, arrowheads). Two small conopea flaps, which cover the areolae, occur on each side of each transapical costa (Figs 36–39), but not distinctive in eroded individuals (Figs 37–38). Striae uniseriate, 40 in 10 μm, formed by round poroids, 50 in 10 μm. Raphe lacking central raphe endings, terminal fissures hooked towards the dorsal side (Figs 34–38). A conopeal canal is present (Fig. 37, double-head arrows, Fig. 39, cc).
FIGURES 40–44. Nitzschia gaoi, sp. nov., internal views, SEM. 40. A whole valve, note the upper apex very slightly arched toward the ventral side. 41–42. Apices, note one apex bending toward the ventral side (Fig. 41, two arrows) and the other almost straight (Fig. 42, two arrows). 43. Central area, note that the zone of valve face subtended by the conopeum (cv) has no areolae in most part but these are present near or on the wall of raphe canal (arrow). 44. Detail of the apex, note the distinctive apical pore field (arrow). Scale bars = 10 μm (Fig. 40), 1 μm (Figs 41–44).
Internal views: One apex bending toward the ventral side and the other almost straight (Figs 40–42). Raphe running continuously from pole to pole and subtended by bar-like fibulae (Figs 40–43). Towards the poles the interspaces between the fibulae very slightly narrower transapically than near the centre of the valve (Fig. 40). Raphe always TWO NEW NITZSCHIA SPECIES FROM CHINA
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rising on a keel and the subtended zones markedly different from the uncovered zones (Fig. 43). The zone of valve face subtended by the conopeum has no areolae in most part but these are present near or on the wall of raphe canal (Fig. 43, cv, arrow). The distinctive apical pore field present (Fig. 44, arrow). Girdle band views: One girdle band open at one apex and close at another apex (Figs 45–47). One transverse row of areolae existing in this girdle band (Figs 46–48) and the areolae covered by hymenes and terminating near each apex (Figs 46, 49, arrows).
FIGURES 45–49. Nitzschia gaoi, sp. nov., girdle band views, SEM. 45. Internal view of a whole valve with one girdle band. 46–47. Apices, note that the girdle band is open at one apex (Fig. 46) but closed at the other (Fig. 47). 48. External view of the apex, note the girdle band (arrow). 49. Apex showing the areolae of the girdle band covered by hymenes and terminating near each apex (Figs 46, 49, arrows). Scale bars = 10 μm (Fig. 45), 1 μm (Figs 46–49).
Etymology:—Named after Professor Yahui Gao of Xiamen University, China, in recognition of his contributions to the study of diatoms. Ecology:—In the sampling site of Yangtang Village, the sediment type (Wentworth scale) is classed as medium silt, salinity of water is 27 ± 1 ppt, pH is 7.98 ± 0.01, and water temperature is 28.1 ± 0.3 °C showing that N. arierae is epipelic and lives in the coastal environment. Observations:—Taking into account the valve outline, N. gaoi resembles N. behrei Husted (1959: 99), N. bartholomei Grunow (in Cleve and Grunow 1880: 102), and a N. spp. described in Krammer & Lange-Bertalot (1988: 126, fig. 86: 5). However the valve of N. behrei is much longer (220–250 μm vs 83–107 μm), and the stria dense of N. bartholomei is much lower (13.5 in 10 μm vs 40 in 10 μm). Moreover, N. behrei and N. bartholomei both do not possess conopeum. The raphe system in N. williamsii Alakananda, P.B.Hamilton & Karthick in Alakananda et al. (2012: 19) is completely eccentric and its apices are not long produced. Nitzschia gaoi is very probably conspecific with the “Nitschia species” described in Krammer & Lange-Bertalot (1988: 126, fig. 86: 5) which was tentatively assigned to N. behrei or N. lorenziana Grunow in Cleve & Möller (1879: 208).
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Discussion Not only N. arierae and N. gaoi both possess the canal-raphe-conopeum system, but they also have other common characteristics such as the keel zone (raphe canal wall) with areolae (e.g. Fig. 21, arrows; Fig. 43, arrow), the hooked terminal fissures towards the dorsal side (e.g. Figs 9, 11, arrowheads; Figs 34–35), and distinctive apical pore fields (e.g. Fig. 9, wavy arrows; Fig. 13; Figs 34–35). In SEM images it can be observed a notable difference between N. arierae and N. gaoi in the zone of valve face subtended by the conopeum, which has areolae in this zone (e.g. Figs 13–16) in the former whereas the latter has no areolae in most part of this zone (e.g. Fig. 43). Species from sections Nitzschiae, Dissipatae, Spathulatae and Lanceolatae sensu lato were included in the subgenus Nitzschia (Mann, 1986), although these groups are probably not natural. As a marine species, N. arierae may fall into the section Spathulatae, with their characteristic ‘Begleitlinien’ present. In contrast, at first glance N. gaoi should fall into the section Nitzschiella because it possesses long, produced, rostrate apices. However, this species clearly belongs to the conopeum-bearing group within Nitzschia. Therefore, in the subgenus Nitzschia there is no section in which N. gaoi may be classified into. Anyway, it can be asserted that N. arierae and N. gaoi are two singular and distinctive members of the subgenus Nitzschia because of their atypical asymmetry pattern and/or ultrastructural features. Further studies will provide a more accurate emplacement of both taxa within this genus, together with new ecological and biogeographic information.
Acknowledgements We are grateful to Mr. Hesheng Zhai of Xiamen University for help with SEM operation and SEM photography, to Mr. Hua Long of Jishou University for assistance with LM. We also owe thanks to two anonymous reviewers for their helpful comments and revision of the manuscript. This work was supported by the key course of Hunan Province (Ecology)/Jishou University and the open fund project of Key Laboratory for Ecotourism of Hunan Province (Grant No. JDSTLY1413).
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Hlúbiková, D., Blanco, S., Falasco, E., Gomà, J., Hoffmann, L. & Ector, L. (2009) Nitzschia alicae sp. nov. and N. puriformis sp. nov., new diatoms from European rivers and comparison with the type material of N. Sublinearis and N. pura. Journal of Phycology 45: 742–760. http://dx.doi.org/10.1111/j.1529-8817.2009.00692.x Hustedt, F. (1922) Bacillariales aus Innerasien. Gesammelt von Dr. Sven Hedin. Southern Tibet, discoveries in former times compared with my own researches in 1906–1908. Lithographic Institute of the General Staff of the Swedish Army. Stockholm 6: 107–152. Hustedt, F. (1959) Die Diatomeenflora der Unterweser von der Lesummündung bis Bremerhaven mit Berücksichtigung des Unterlaufs der Hunte und Geeste. Veröffentlichungen des Institut für Meereforschung in Bremenhaven 6: 13–176. Knattrup, A., Yde, M., Lundholm, N. & Ellegaard, M. (2007) A detailed description of a Danish strain of Nitzschia sigmoidea, the type species of Nitzschia, providing a reference for future morphological and phylogenetic studies of the genus. Diatom Research 22: 105–116. http://dx.doi.org/10.1080/0269249X.2007.9705698 Krammer, K. & Lange-Bertalot, H. (1988) Bacillariophyceae. 2 Teil. Bacillariaceae, Epithemiaceae, Surirellaceae.-Die Süsswasserflora von Mitteleuropa 2/2. Gustav Fischer Verlag, Jena, 596 pp. Lakhan, V.C. (2003) Advances in Coastal Modeling. Elsevier, Amsterdam, 614 pp. Liu, B., Williams, D.M. & Huang, B.Q. (2015a) Gyrosigma rostratum sp. nov. (Bacillariophyta) from the low intertidal zone, Xiamen Bay, southern China. Phytotaxa 203 (3): 254–262. http://dx.doi.org/10.11646/phytotaxa.203.3.4 Liu, B., Sterrenburg, F.A.S. & Huang, B.Q. (2015b) Gyrosigma xiamenense sp. nov. (Bacillariophyta) from the middle intertidal zone, Xiamen Bay, southern China. Phytotaxa 222 (4): 259–266. http://dx.doi.org/10.11646/phytotaxa.222.4.3 Lobban, C.S. & Mann, D.G. (1987) The systematics of the tube-dwelling diatom Nitzschia martiana and Nitzschia section Spathulatae. Canadian journal of botany 65: 2396–2402. http://dx.doi.org/10.1139/b87-326 Lund, J.W.G. (1946) Observations on soil algae I. The ecology, size and taxonomy of British soil diatoms. Part 2. New Phytologist 45: 56–110. http://dx.doi.org/10.1111/j.1469-8137.1946.tb05047.x Mann, D.G. (1978) Studies in the Nitzschiaceae (Bacillariophyta). Vols. 1 & 2. Ph.D. Dissertation, University of Bristol, Bristol, 386 pp. Mann, D.G. (1986) Nitzschia subgenus Nitzschia (Notes for a monograph of the Bacillariaceae 2). In: Ricard, M. (Ed.) Proceedings of the 8th International Diatom Symposium. O. Koeltz, Königstein, pp. 215–226. Mann, D.G. & Trobajo, R. (2014) Symmetry and sex in Bacillariaceae (Bacillariophyta), with descriptions of three new Nitzschia species. European Journal of Phycology 49: 276–297. http://dx.doi.org/10.1080/09670262.2014.915063 Nitzsch, C.L. (1817) Beitrag zur Infusorienkunde oder Naturbeschreibung der Zerkarien und Bazillarien. Neue Schriften der Naturforschenden Gesellschaft zu Halle 3: 1–128. Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. & Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell. Nova Hedwigia, Beiheft 64: 513–533. Round, F.E., Crawford, R.M. & Mann, D.G. (1990) The diatoms: biology and morphology of the genera. Cambridge University Press, Cambridge, 747 pp. Smith, W. (1853) A synopsis of the British Diatomaceae with remarks on their structure, function and distribution; and instructions for collecting and preserving specimens. Vol. 1. John Van Voorst, London, 89 pp. Sterrenburg, F.A.S., Hamilton, P. & Williams, D. (2012) Universal coordinate method for locating light-microscope specimens. Diatom Research 27: 91–94. http://dx.doi.org/10.1080/0269249X.2012.688493
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