Fottea, Olomouc, 13(2): 87–104, 2013 87 Epilithic diatoms of springs and spring–fed streams in Majorca Island (Spain) with the description of a new diatom species Cymbopleura margaleii sp. nov. Cristina DelgaDo1,2*, Luc ector2, Maria Helena Novais2, Saúl BlaNco3, Lucien HoffmaNN2 & Isabel ParDo1 1 Departamento de Ecología y Biología Animal, Universidad de Vigo, E–36330 Vigo, Spain; *Corresponding author e–mail: cdelgado.cristina@gmail.com 2 Department of Environment and Agro–biotechnologies (EVA), Public Research Centre – Gabriel Lippmann, Rue du Brill 41, L–4422 Belvaux, Luxembourg 3 Instituto de Medio Ambiente, Universidad de León, E–24071 León, Spain Abstract: The Island of Majorca (Spain) is characterized by a Mediterranean climate and a karstic geology that favors the formation of numerous springs and spring–fed streams on the island’s Northwester zone. Water and epilithic diatom samples were collected from two springs and four spring–fed streams, located at altitudes ranging from 0 to 756 m a.s.l., in different seasons between 2005 and 2008. Water chemistry in these systems is characterized by high concentrations of dissolved calcium and pH values ranging from 6.6 to 8.4. A total of 111 diatom taxa belonging to 40 genera were found and the most abundant taxa were illustrated with LM and SEM. The diatom communities of the studied sites were dominated by species such as Achnanthidium minutissimum, A. pyrenaicum, Amphora pediculus, Cymbella vulgata, Diploneis separanda, Encyonopsis minuta, Gomphonema lateripunctatum and Navicula cryptotenella, relecting the calcareous geological nature of Majorca Island. In the framework of the study 22 diatom taxa, which are new for Balearic Islands were recorded, such as Achnanthidium straubianum, Amphora indistincta, Cymbella lange–bertalotii, Encyonopsis subminuta, Karayevia kolbei, Navicula aff. margalithii, N. reichardtiana and N. subalpina. In addition, a new freshwater diatom species belonging to the genus Cymbopleura, C. margaleii was found in the Torrente of Deià. Cymbopleura margaleii is described as a new species based on LM and SEM observations, and compared with similar taxa. A checklist of the 309 diatom taxa recorded so far from the Balearic Islands is also presented. Key words: Bacillariophyta, Balearic Islands, diatoms, karstic springs, Mediterranean climate, new species, Serra de Tramuntana IntroductIon Mediterranean streams are subjected to high temporal variation inluenced by climatic factors (saBater et al. 1991) with high rainfall levels occurring in autumn and spring (ParDo & Álvarez 2006). Under the Mediterranean climate, groundwater hydrology is as important as surface hydrology for the persistence and functioning of aquatic ecosystems because a high number of streams are fed by springs. Diatom assemblages are adapted to the local environmental conditions in relation to changes in water residence time and to the variations in the ionic content in water due to variations in low volume (aBoal et al. 1996). Diatom communities inhabiting springs have been studied in several mountainous regions in Europe, including the Pyrenees (saBater & roca 1990, 1992), the mountains of central Germany (Werum & laNge– Bertalot 2004) and the Alps (caNtoNati et al. 2006, 2012; caNtoNati & laNge–Bertalot 2010; gesiericH & Kofler 2010). Majorca is the largest of the Balearic Islands that are located in the western part of the Mediterranean Sea. The island is geologically very homogeneous, constituted by calcareous rocks where rainfall water causes karstic erosion and favours water iniltration. Topographically, it is a heterogeneous island with mountainous regions in the Northwest and lowlands in the South. The Tramuntana mountain range extends parallel to the northwest coast and presents geological structures that favour the formation of numerous springs and spring–fed streams. Around 700 springs, all with different sizes and discharge categories, can originate from the limestone rocks (lloBera & ferriol 1994) where water mineralization is an important feature (moyÁ et al. 1991). These systems are geographically isolated and their chemical characteristics and temperature make them an exceptional type of habitat for the study of algae, especially diatoms, organisms that can be considered useful indicators of spring characteristics (saBater & roca 1990). The spring 88 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams is mainly viewed as the origin of a stream and this leads to an investigation of the physical and chemical characteristics and of the composition and structure of the communities (caNtoNati et al. 2006). Many temporary streams in the Balearic Islands have their origin in springs, and constitute refugia for the lora and fauna that colonise the streams when water low initiates each rainy season (ParDo & Álvarez 2006). The spring systems in Majorca Island have previously been studied by moyÁ et al. (1991) and lloBera & ferriol (1994), but none of these studies have provided information on the diatom lora composition. Some phycological studies performed in the Balearic Islands reported only some diatom species from Majorca, Minorca and Ibiza (see references in Appendix 1). There are also taxonomic checklists available, including diatom data exclusively from the Balearic Islands (alvarez coBelas & estévez garcía 1982; camBra et al. 1991; aBoal et al. 2003). Nevertheless, none of them illustrates the diatom species that appear in the Balearic Islands or provide information about their ecological preferences. The objectives of this study were: i) to increase the knowledge on the epilithic diatom communities inhabiting springs and spring–fed streams in Majorca Island; ii) to illustrate their most characteristic diatom taxa under light and electron microscopy and iii) to elaborate a checklist with all the diatom taxa identiied up to date in the Balearic Islands. for 25 ºC, and pH with a Termo Orion 290+. Water samples for chemical analyses were collected into polypropylene bottles and transported chilled to the laboratory. In the ield, water velocity was measured using a current meter Probe (Flow probe, model FP101; Global water instrumentation, Gold River, California), as an average of three recordings in one transect of the stream. Flow was estimated multiplying this value by the transect area. Epilithic diatoms were collected from hard natural substrata (stones), following the European Standard (ceN 2003), with a toothbrush and preserved with a formaldehyde solution (4% v/v) immediately after sampling. Ash free dry mass (AFDM) and chlorophyll a (Chl–a) were measured from epilithic samples from the upper side of three stones using a toothbrush and rinsed with distilled water. The surface areas of the stones were measured by wrapping them tightly in tin foil (for more information see DelgaDo et al. 2012). The samples were stored in ice, kept in darkness and transported to the laboratory. Three samples were used to estimate epilithon biomass as AFDM and the additional three samples were used for the analysis of Chl–a. Laboratory methods. Standard methods for the chemical analysis of water followed APHA (1995). Alkalinity was determined by the potentiometric method; N–NO3–, SiO2 and PO43– with a nutrient auto–analyzer (Auto–Analyzer 3, Bran + Luebbe, Germany), and ions Ca2+, Mg2+, K+ and Na+ with a mass spectrophotometer. Chlorides (Cl–) and sulphates MaterIal and Methods Study sites. The material included in this study was collected in two springs (Font de s’Olla and Font des Pí) and in four spring–fed streams (Tte. des Prat, Tte. de Son Vic, Tte. de Deià and Son Sant Joan). All sites are located in the Northern part of Majorca Island and have water during most part of the year. Five of them (Font de s’Olla, Font des Pí, Tte. des Prat, Tte. de Son Vic and Tte. de Deià) are located in the Tramuntana mountains at elevations ranging between 55 and 732 m a.s.l. (Fig. 1; Table 1). The Son Sant Joan spring is located at sea level, beside the S’Albufera of Majorca, which is the largest and most important wetland area in the Balearic Islands. It is a former lagoon separated from the sea by a belt of dunes, which for many centuries – but especially in the last two and as a result of human inluence – has been illed up with sediments converting it into an extensive lood plain. Water and epilithic diatom samples were collected in spring–fed streams during spring, autumn and winter between 2005 and 2008. A total of 31 samples were analysed in this study. Spring samples were taken at the same time in the spring–fed streams but only when water was present in these systems (Table 1). Sampling. Water samples for chemical analysis were collected from running water. Temperature (ºC), pH, dissolved oxygen (mg.l–1) and electric conductivity (µS.cm–1) were measured in situ with portable meters. Water temperature and dissolved oxygen were measured with a WTW Oxi 197 oxymeter, conductivity with an Orion Model 115 corrected Fig. 1. Location of sampled sites in Majorca Island (Spain): (1) Font de s’Olla ; (2) Font des Pí; (3) Tte. de Deià ; (4) Tte. des Prat; (5) Tte. de Son Vic; (6) Son Sant Joan. Fottea, Olomouc, 13(2): 87–104, 2013 89 Table 1. Characterization and sampling period of the study sites in Majorca Island. Site Site location Latitude Longitude Elevation (m a.s.l.) Spring Font des Pì Alaró-Escorça 39º 46‘ 14‘‘ N 2º 48‘ 26‘‘E 470 Font de s‘Olla Soller 39º 45‘ 23‘‘ N 2º 42‘ 42‘‘E 55 Tte. des Prat Escorça 39º 47‘ 01‘‘ N 2º 49‘ 53‘‘E 732 + Tte. Son Vic Puigpunyent 39º 39‘ 12‘‘ N 2º 32‘ 08‘‘E 356 + Son Sant Joan Muro 39º 46‘ 02‘‘ N 3º 05‘ 17‘‘E 0 Tte. de Deià 39º 44‘ 49‘‘ N 2º 38‘ 31‘‘E 178 2005 Deià (SO42–) were measured with Inductively Coupled Plasma – Mass Spectrometry (ICP–MS). Samples for chlorophyll–a (Chl–a) analysis were iltered through glass iber ilters and extracted with acetone for 48 h at 4 ºC in the dark. After extraction, Chl–a was measured spectrophotometrically (Hitachi Model U–2001 UV/Visible Spectrophotometer) and corrected (loreNzeN 1967). Three periphyton samples were iltrated and dried until constant weight (DM) at 70 ºC and ashed at 500 ºC for 2 hours to determine the ash free dry mass (AFDM). Diatom analysis. Diatom samples were treated to obtain a suspension of clean frustules. Organic matter was eliminated using hydrogen peroxide (33%) and HCl (37%) was added to remove the calcium carbonate (reNBerg 1990). Finally, after rinsing with distilled water, permanent slides were mounted using Naphrax®, a synthetic mounting medium with high refractive index. Diatoms were identiied to species or subspeciic levels using a Leica® DMRX light microscope (LM) with a 100× oil immersion objective and light microscopy photographs were taken with a Leica® DC500 camera. At least 400 valves were identiied and counted from each slide to estimate the relative abundance of each taxon. Diatom samples for scanning electron microscopy analysis were iltered through polycarbonate membrane ilters with a pore diameter of 3 μm, mounted on stubs, sputtered with gold (40 nm) with Modular High Vacuum Coating System (BAL– TEC MED 020) and studied with a Leica® Stereoscan 430i electron microscope, operated at 20 kV. Micrographs were digitally manipulated and plates containing LM and SEM pictures were mounted using CorelDRAW X5. Diatoms were identiied to the lowest taxonomical level according to usual current taxonomic literature, e.g. Krammer & laNge–Bertalot (1986–1991, 2004), simoNseN (1987), laNge–Bertalot & Krammer (1989), laNge– Bertalot (1993, 1999, 2001), laNge–Bertalot & moser (1994), Krammer (1997a, b, 2002), WitKoWsKi et al. (2000), tuji & HouKi (2004), Werum & laNge–Bertalot (2004), levKov (2009), levKov et al. (2010), Żelazna–Wieczorek (2011) and troBajo et al. (2013). New loristic records were determined checking the references of the phycological studies from the Balearic Islands since 1889 and also the diatom checklist with records from the Balearic Islands (alvarez coBelas & estévez garcía 1982; camBra et al. 1991; aBoal et al. 2003) (Appendix 1). + Autumn 2006 2008 + + 2005 Winter 2006 2008 + + + + + + + + + + + + + + + + + + + + + + + + + + results and dIscussIon Physical and chemical characterization of studied sites Benthic communities found in the Majorcan streams are inluenced by different factors, such as orography, pronounced seasonal irregularity in rainfall levels and predominance of the karstic geology (ParDo & Álvarez 2006). Calcium concentrations are high in the studied streams because of the dissolution of the calcareous substratum, ranging from 22.9 to 151.4 mg.l–1 (Table 2). In consequence water pH was neutral to alkaline (from 6.6 to 8.4). Water temperature ranged annually between 12.5 and 19.1 ºC, indicating high temperature stability in ive of these systems, except for Tte. des Prat. This site showed the largest annual luctuation (9.4 to 25.2 ºC), attributed to its mountainous location at 732 m a.s.l. The studied sites with higher values of SiO2 were Tte. de Son Vic and Son San Joan, with mean values around 5 mg.l–1 (Table 2). Son San Joan showed the highest N–NO3 and chlorophyll–a mean values with respect to other studied sites, while SO42– has mean values ranged between 74.0 to 139.5 mg.l–1 in most sites, except for Font des Pí that has the lowest mean value 28.0 mg.l–1. Tte. de Deià showed the highest AFDM mean values (29.4 g.m–2) with respect to other sites. Son San Joan also showed high values of water low, electric conductivity, Cl–, K+, Mg2+, Na+, N– NO3– and SO42– attributed to its location near to the sea and beside the S’Albufera that has a high human inluence in the last two decades, with large increase of agricultural activities in the area. Diatom assemblages A total of 111 diatom taxa belonging to 40 genera were identiied in this study, but only 19 species represented more than 5% in at least one sample (Table 3, in bold). These and other diatom taxa which characterized some sites, including new records for the Balearic Islands, were illustrated under LM and SEM (Figs 2–204). The diatom assemblages of the studied sites were characterized by high taxa richness especially within 90 Table 2. Range, average (AVG) and standard deviation (STD) values of physical, chemical, chlorophyll–a and AFDM data from the study sites. AFDM: Ass - free dry mass. Font des Pí (n=4) Range AVG ± STD Font de s‘Olla (n=4) Range AVG ± STD Tte. des Prat (n=6) Range AVG ± STD Tte. Son Vic (n=6) Range AVG ± STD Son Sant Joan (n=5) Range AVG ± STD Tte. de Deià (n=6) Range AVG ± STD Temperature (oC) 12.5 - 15.0 13.3 ± 1.2 15.6 - 18.8 16.5 ± 1.6 9.4 - 25.2 15.3 ± 6.4 14.4 - 17.2 15.7 ± 1.1 15.4 - 19.1 17.7 ± 1.5 14.9 - 18.3 16.6 ±1.4 Conductivity (mS.cm-1) 328.5 - 495.0 406.4 ± 69.3 440 - 621.5 559.4 ± 83.5 518.3 - 817.8 635.5 ± 110.0 791.0 - 1532.1 962.1 ± 290.6 2110 - 3084 2426.8 ± 383.9 472.0 -725.1 578.2 ± 102.1 pH 7.4 ± 0.6 7.2 - 8.2 7.6 ± 0.4 8.0 - 8.4 8.2 ± 0.1 6.9 - 7.9 7.3 ± 0.4 6.9 - 7.4 7.2 ± 0.2 7.4 -8.4 8.1 ± 0.4 8.4 - 10.5 9.3 ± 1.0 9.0 - 16.7 11.4 ± 3.7 9.2 - 10.7 9.8 ± 0.6 1.9 - 7.3 4.7 ± 2.0 7.2 - 8.5 7.7 ± 0.5 8.2 - 10.0 9.1 ± 0.7 Water low (l.s-1) 0 - 135.0 33.7 ± 67.5 0.0 - 42.2 26.0 ± 18.7 0.0 - 47.5 8.5 ± 19.1 0.0 - 16.6 5.7 ± 6.9 0.0 - 262.3 150.0 ± 103.1 0.0 - 110.9 20.8 ± 44.4 Chlorophyll-a (mg.m-2) 1.4 - 16.6 9.2 ± 6.2 0.9 - 62.4 17.5 ± 30.0 3.5 - 18.8 7.8 ± 5.9 0.4 - 70.2 21.8 ± 25.6 10.0 - 49.3 31.4 ± 15.4 6.7 - 31.4 16.1 ± 9.3 AFDM (g.m-2) 1.2 - 18.1 8.6 ± 7.5 1.0 - 18.9 7.8 ± 8.6 4.9 - 18.0 9.4 ± 5.0 4.5 - 43.1 14.8 ± 14.9 7.5 - 16.5 11.5 ± 4.1 4.9 - 48.8 29.4 ± 19.5 4.1 - 6.8 5.3 ± 1.2 4.3 - 6.1 5.4 ± 0.9 4.0 - 6.9 5.3 ± 1.2 6.2 - 10.1 8.2 ± 1.5 4.6 - 7.0 5.5 ± 1.0 3.5 - 6.8 4.9 ± 1.1 13.6 - 38.4 28.0 ± 11 56.6 - 100.4 74.0 ± 18.8 87.0 - 183.5 139.5 ± 31.1 76.9 - 116.6 95.5 ±13.7 112.3 - 140.3 127.4 ± 11.5 21.4 - 106.1 82.3 ± 30.6 0.1 - 0.8 0.5 ± 0.5 0.2 - 0.4 0.3 ± 0.2 0.0- 0.7 0.2 ± 0.3 0.1 - 1.4 0.5 ± 0.6 1.7 - 20.1 9.6 ± 9.5 0.2 - 0.6 0.4 ± 0.2 Alkalinity (meq.l-1) SO42- (mg.l-1) -1 - N-NO3 (mg.l ) -1 SiO2 (mg.l ) 1.4 - 2.5 1.9 ± 0.5 2.0 - 2.4 2.2 ± 0.2 1.9 - 3.9 2.7 ± 0.9 2.1 - 12.1 5.0 ± 3.6 2.5 - 6.2 4.6 ± 1.5 1.7 - 4.4 2.7 ± 0.9 Ca2+ (mg.l-1) 43.5 - 81.2 61.3 ± 19.8 49.6 - 97.5 64.5 ± 22.2 39.1 - 128.4 93.1 ± 32.8 54.7 - 151.4 85.2 ± 35.6 61.8 -115.0 74.3 ± 22.5 22.9 - 100.7 62.1 ± 25.9 15.7 - 185.7 59.9 ± 83.9 24.1 - 25.7 24.7 ± 0.8 21.4 - 57.8 30.9 ± 13.6 39.5 - 352.1 100.6 ± 123.7 156.5 - 846.5 379.9 ± 274.1 18.7 - 373.9 86.7 ± 140.9 0.5 - 1.0 0.8 ± 0.2 0.4 - 1.6 1.0 ± 0.5 0.4 - 1.9 1.1 ± 0.5 0.8 - 3.3 1.9 ± 0.8 7.5 -18.9 11.8 ± 5.4 0.5 - 1.8 1.1 ± 0.5 Cl- (mg.l-1) + -1 K (mg.l ) 2+ -1 Mg (mg.l ) 6.3 - 13.0 9.9 ± 3.6 8.2 - 22.5 13.4 ± 6.5 19.2 - 43.2 33.0 ± 9.3 13.2 - 39.3 29.6 ± 10.0 28.9 - 68.5 54.0 ± 17.8 11.9 - 23.4 18.6 ± 4.9 Na+ (mg.l-1) 9.7 - 13.2 11.0 ± 1.5 11.6 - 17.0 13.9 ± 2.5 6.6 - 24.7 15.5 ± 6.7 13.9 - 39.0 24.9 ± 9.4 163.5 - 410.7 252.6 ± 110.5 9.2 - 25.3 17.5 ± 6.5 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams 6.6 - 8.1 Dissolved oxygen (mg.l-1) Fottea, Olomouc, 13(2): 87–104, 2013 Figs 2–25. LM: (2–6) Achnanthidium minutissimum (KütziNg) czarNecKi. Tte. des Prat 15/05/06; (7–13) Amphora pediculus (KütziNg) gruNoW ex a. scHmiDt, Son Sant Joan 25/05/06; (14–18) Planothidium frequentissimum (laNge–Bertalot) laNge–Bertalot, Font de s’Olla 13/12/05; (19) Navicula subalpina e. reicHarDt, Font des Pí 13/05/06; (20–22) Navicula cryptotenella laNge–Bertalot, Tte. de Son Vic 19/05/05; (23–25) Navicula wygaschii laNge– Bertalot, Son San Joan 12/03/2006. Scale bar 10 µm. the genera Gomphonema, Navicula and Nitzschia as in studies carried out in different springs in the Alps (caNtoNati et al. 2006; gesiericH & Kofler 2010). Only three taxa appeared in all localities: Achnanthidium minutissimum (KütziNg) czar-NecKi sensu lato (Figs 2–6) showing high abundance in all samples, Amphora pediculus (KütziNg) gruNoW ex a. scHmiDt (figs 7–13) and Navicula cryptotenella laNge–Bertalot (Figs 20– 22) (Table 3). However, the most frequent taxon found in this study was A. minutissimum sensu lato, which is a common cosmopolitan component of the benthic diatom communities and is also abundant in the streams of Majorca (DelgaDo et al. 2012) and in Alpine springs (gesiericH & Kofler 2010). Planothidium frequentissimum (laNge–Bertalot) laNge–Bertalot (Figs 14–18), Gomphonema micropus KütziNg and Nitzschia inconspicua gruNoW appeared in this study in waters with the highest values of chlorophyll a and AFDM, whereas Gomphonema lateripunctatum e. reicHarDt et laNge–Bertalot, Fragilaria sp. and Encyonopsis krammeri e. reicHarDt occured with values of dissolved calcium above 80 mg.l–1. Spring–fed streams The Son Sant Joan spring had the most singular diatom community, with high abundances of Achnanthidium minutissimum, Amphora pediculus (Figs 7–13), Navicula aff. margalithii laNge–Bertalot (Figs 26–28), Nitzschia inconspicua (Figs 41–51) and 91 Rhoicosphenia abbreviata (c. agarDH) laNge– Bertalot (Figs 29–31). Noticeable was the presence of Navicula wygaschii laNge–Bertalot (Figs 23–25), Amphora indistincta levKov (Figs 39–40), A. ovalis (KütziNg) KütziNg, Karayevia kolbei (HusteDt) BuKHtiyarova (Figs 32–38), Encyonopsis sp. 2, Achnanthes coarctata (BréBissoN ex W. smitH) gruNoW and A. brevipes var. intermedia (KütziNg) cleve (Figs 52–57), species recorded only in this locality, usually related with brackish wetlands in Italy (Della Bella et al. 2007). These records reinforce the idea that this community is inluenced by marine water, in agreement with the high conductivity values found (mean values of 2427 µS.cm–1) (Table 2). According to troBajo et al. (2013), Nitzschia inconspicua extends from freshwater into brackish and marine water. Nitzschia inconspicua and Navicula aff. margalithii appeared under high conductivities such as the waters at this site, and N. aff. margalithii and Rhoicosphenia abbreviata also associated with the highest values of nitrates. Son Sant Joan spring rises at sea level presenting the highest conductivity and concentrations of sodium and chlorine ions, attributed to sea proximity inluence. In Son Sant Joan the value of N–NO3– was above 20 mg.l–1 (Table 2), which is related to the subterranean input of nutrients from agricultural surrounding areas of the S’Albufera de Majorca. Some springs in Sardinia Island also host diatom assemblages under high to very high electric conductivities values and strong alkaline conditions (laNge–Bertalot et al. 2003). Navicula wygaschii (Figs 23–25) is reported for the irst time out of its type locality (Thüler Moorkomplex, Germany). Tte. de Son Vic had high percentages of Navicula cryptotenella, Diploneis separanda laNge– Bertalot (Figs 58–64), originally described from German springs by Werum & laNge–Bertalot (2004), and Nitzschia denticula gruNoW (Figs 65– 68) in autumn. The occurrence of Brachysira vitrea (gruNoW) r. ross (Figs 76–79), Eunotia arcubus NörPel et laNge–Bertalot (Figs 69–72) and Cymbella afinis KütziNg (Figs 73–75) is remarkable. Cymbella afinis is a cosmopolitan taxon particularly abundant in alkaline waters, preferring waters with high electrolyte content (Krammer 2002), that many authors have previously misidentiied as C. tumidula Grunow. Our photographs of C. afinis (Figs 74, 75) it well with the light microscope photographs from England, France, Germany and Serbia published in Krammer (2002) but not with SEM photographs from West Germany and New Zealand in Krammer (2002) where the valves have slightly radiate and inely punctuate striae (Fig. 73). In Tte. de Son Vic, dissolved oxygen concentration reached a minimum value of 1.9 mg.l–1 in autumn, attributed to slow water low and high leaf litter accumulation (Table 2). Achnanthidium straubianum (laNge–Bertalot) laNge–Bertalot (Figs 80–91; 96– 98) and Fragilaria sp. (Figs 92–95) are two taxa with percentages of abundance above 5% in Tte. de Son 92 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams Table 3. List of taxa identiied in the studied sites. Percentage of abundance of each taxa: (1) rare, <1.5%; (2) frequent, 1.5–5%; (3) abundant, >5%. Bold: taxa with relative abundance above 5% at least in one site. Taxa Font des Pí Font de s‘Olla Tte. des Prat Tte. Son Vic Son Sant Joan Achnanthes brevipes var. intermedia (KütziNg) cleve 1 Achnanthes coarctata (BréBissoN ex W. smitH) gruNoW 1 Achnanthes parvula KütziNg 1 Achnanthes sp. 1 1 Achnanthes sp. 2 1 Achnanthidium minutissimum (KützIng) czarnecKI 3 3 3 3 Achnanthidium pyrenaicum (hustedt) h. KobayasI 3 1 2 2 1 2 1 Achnanthidium straubianum (laNge-Bertalot) laNge-Bertalot 3 3 3 2 Achnanthidium thermale raBeNHorst Achnanthidium sp. 1 Adlaia bryophila (j.B. PeterseN) gerD moser, laNge-Bertalot et metzeltiN 1 Amphora indistincta levKov 1 2 2 2 1 Amphora libyca eHreNBerg 1 Amphora ovalis (KütziNg) KütziNg Amphora pediculus (KützIng) grunow Tte. de Deià 2 3 2 1 2 3 3 1 Bacillaria paxillifera (o.f. müller) HeNDey Brachysira vitrea (gruNoW) r. ross 1 Caloneis lancettula (scHulz) laNge-Bertalot et Wit- 1 2 2 1 1 1 1 1 2 KoWsKi Caloneis sp. 2 Cocconeis euglypta eHreNBerg Cocconeis lineata eHreNBerg 1 2 1 2 3 1 Cymbella afinis KütziNg 1 Cymbella lange-bertalotii Krammer 2 1 2 Cymbopleura margaleii sp. nov. 3 2 1 1 2 1 Denticula subtilis gruNoW Denticula tenuis Kützing 3 1 Diadesmis contenta (grunow ex Van heurcK) d.g. Mann 3 3 Diploneis elliptica (KütziNg) cleve 2 1 Craticula halophila (gruNoW ex vaN HeurcK) D.g. maNN Cymbella vulgata KraMMer 1 2 1 1 Fottea, Olomouc, 13(2): 87–104, 2013 93 Table 3 Cont. Diploneis krammeri laNge-Bertalot et reicHarDt e. Diploneis ovalis (Hilse) cleve Diploneis separanda lange-bertalot 1 1 1 2 1 1 Diploneis sp. Encyonema minutum (Hilse) D.g. maNN 1 1 1 3 3 1 3 Encyonopsis minuta KraMMer et e. reIchardt Encyonopsis subminuta Krammer et e. reicHarDt 2 2 Encyonopsis cesatii (raBeNHorst) Krammer Encyonopsis krammeri e. reIchardt 3 2 1 1 3 1 1 Encyonopsis sp. 1 2 Encyonopsis sp. 2 Eolimna minima (gruNoW) laNge-Bertalot 1 1 1 1 2 2 Eunotia arcubus NörPel et laNge-Bertalot 1 Fallacia pygmaea (KütziNg) sticKle et D.g. maNN Fragilaria aff. rumpens (KütziNg) g.W.f. carlsoN 1 1 Eolimna subminuscula (maNguiN) gerD moser, laNge-Bertalot et metzeltiN Epithemia adnata (KütziNg) BréBissoN 2 1 2 1 Fragilaria vaucheriae (KütziNg) j.B. PeterseN 1 1 Fragilaria sp. 3 Frustulia sp. 1 Gomphonema bavaricum e. reicHarDt et laNge-Berta- 1 lot Gomphonema gracile eHreNBerg 1 Gomphonema lateripunctatum e. reIchardt et lange-bertalot 1 Gomphonema micropus KützIng 2 Gomphonema minutum (c. agarDH) c. agarDH 1 1 1 3 3 1 3 1 1 1 1 1 2 2 2 1 1 2 1 1 Gomphonema olivaceum (HorNemaNN) BréBissoN Gomphonema parvulum KütziNg 2 Gomphonema pumilum (gruNoW) e. reicHarDt et laNge-Bertalot 2 Gomphonema rosenstockianum laNge-Bertalot et e. reicHarDt 1 Gomphonema truncatum eHreNBerg Gomphonema sp. 1 Halamphora coffeaeformis (c. agarDH) levKov Halamphora montana (KrassKe) levKov Halamphora veneta KütziNg Hippodonta hungarica (gruNoW) laNge-Bertalot, meet WitKoWsKi tzeltiN 1 1 1 1 1 1 1 1 1 1 1 1 94 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams Table 3 Cont. 2 Karayevia kolbei (HusteDt) BuKHtiyarova 1 Luticola mutica (KütziNg) D.g. maNN Meridion circulare (greville) c. agarDH 2 Navicula antonii laNge-Bertalot et rumricH 1 Navicula cryptotenella lange-bertalot 2 Navicula cryptotenelloides laNge-Bertalot 1 Navicula cryptocephala KütziNg 1 1 2 1 1 2 3 1 1 1 3 2 Navicula radiosa KütziNg Navicula reichardtiana lange-bertalot 3 Navicula subalpina e. reicHarDt 1 Navicula tripunctata (o.f. müller) Bory 1 1 1 1 1 2 1 1 1 2 Navicula wygaschii laNge-Bertalot 1 Navicula sp. 1 1 1 Nitzschia amphibia gruNoW 1 1 1 1 1 2 2 1 1 1 Nitzschia denticula grunow Nitzschia dissipata (KütziNg) gruNoW 1 1 Navicula aff. margalithii lange-bertalot Nitzschia bacillum HusteDt 2 2 Navicula leptostriata e.g. jørgeNseN Navicula sp. 2 2 1 Navicula lanceolata (c. agarDH) KütziNg Navicula veneta KütziNg 1 1 1 Navicula gregaria DoNKiN 2 3 1 1 1 Nitzschia fonticola (gruNoW) gruNoW 1 1 Nitzschia frustulum (KütziNg) gruNoW Nitzschia inconspicua grunow 2 Nitzschia lacuum laNge-Bertalot 1 1 1 1 1 3 1 1 Nitzschia palea (KütziNg) W. smitH 1 1 Nitzschia recta HaNtzscH ex raBeNHorst 1 1 Nitzschia sigmoidea (NitzscH) W. smitH 1 1 Nitzschia tabellaria (gruNoW) gruNoW 1 Nitzschia sp. 1 Pinnularia sp. 1 Planothidium dubium (gruNoW) rouND et BuKHtiyarova Planothidium frequentissimum (lange-bertalot) lange-bertalot 1 1 3 2 Planothidium lanceolatum (BréBissoN ex KütziNg) laNge-Bertalot 1 1 Pseudostaurosira brevistriata (gruNoW) D.m. Williams et rouND 1 1 1 1 Fottea, Olomouc, 13(2): 87–104, 2013 95 Table 3 Cont. Reimeria sinuata (gregory) KocioleK et stoermer 1 Rhoicosphenia abbreviata (c. agardh) lange-berta- 1 2 3 lot 1 Rhopalodia gibba (eHreNBerg) o.f. müller 1 Sellaphora seminulum (gruNoW) D.g. maNN 1 1 Sellaphora stroemii (HusteDt) H. KoBayasi 1 1 2 Tabularia fasciculata (c. agarDH) D.m. Williams et rouND 1 Tryblionella apiculata W. gregory 1 Ulnaria acus (KütziNg) aBoal Ulnaria ulna (NitzscH) comPère 3 1 1 1 2 2 Figs 26–57. SEM and LM: (26–28) Navicula aff. margalithii laNge–Bertalot, Son Sant Joan 12/03/06; (29–31) Rhoicosphenia abbreviata (c. agarDH) laNge–Bertalot, Son Sant Joan 23/05/06; (32–38) Karayevia kolbei (HusteDt) BuKHtiyarova, Son Sant Joan 25/05/06; (39–40) Amphora indistincta levKov, Son San Joan 23/05/06; (41–51) Nitzschia inconspicua gruNoW, Son Sant Joan 13/03/06; (52–57) Achnanthes brevipes var. intermedia (KütziNg) cleve, Son Sant Joan 12/03/06. Scale bar 10 µm. 96 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams Figs 58–98. LM and SEM: (58–64) Diploneis separanda laNge–Bertalot, Tte. de Son Vic 06/11/05 ; (65–68) Nitzschia denticula gruNoW, Tte. de Son Vic 6/11/05; (69–72) Eunotia arcubus NörPel et laNge–Bertalot, Tte. de Son Vic 19/05/05; (73–75) Cymbella afinis KütziNg, Tte. de Son Vic 19/05/05; (76–79) Brachysira vitrea (gruNoW) ross, Tte. de Son Vic 19/05/05; (80–91, 96–98) Achnanthidium straubianum (laNge–Bertalot) laNge–Bertalot, Tte. de Son Vic 06/11/05; (92–95) Fragilaria sp., Tte de Son Vic 19/05/05. LM scale bar 10 µm, SEM scale bars 10 µm (Figs 64, 68, 73, 76, 92), 5 µm (Figs 62–63, 96–98), 1 µm (Figs 71–72, 93–95). Vic. Achnanthidium straubianum also appear in Tte. des Prat and is one of the new citations for the Balearic Islands (Appendix 1). Tte. des Prat is characterized by the presence of Achnanthidium pyrenaicum (HusteDt) H. KoBayasi, Cymbella vulgata Krammer (Figs 101–102; 151–154), Diploneis separanda, Gomphonema lateripunctatum (Figs 130–135; 150) and different species of Encyonopsis (Figs 103–129). Cymbella vulgata was recently found also in freshwaters in Lluc, Majorca (Krammer 2002). Different species of the genus Encyonopsis, formerly grouped under the Cymbella microcephala gruNoW complex, and separated by Krammer (1997b), were identiied in this locality indicating similarity in the ecological tolerance of these species. Encyonopsis minuta Krammer et e. reicHarDt (Figs 160; 163–164) is the most abundant taxon and appeared together with E. cesatii (raBeNHorst) Krammer (Figs 155–158), E. krammeri, E. subminuta Krammer et e. reicHarDt (Figs 142–144) and Encyonopsis sp. 1 (Figs 147–149). Gomphonema lateripunctatum is a highly alkaliphilous species of mountain and lowland watercourses and is Fottea, Olomouc, 13(2): 87–104, 2013 97 Figs 99–129. LM: (99–100) Cymbella lange–bertalotii Krammer, Tte. des Prat 25/05/05; (101–102) Cymbella vulgata Krammer, Tte. des Prat 15/05/06; (103–104) Encyonopsis cesatii (raBeNHorst) Krammer, Tte. des Prat 25/05/05; (105) Encyonopsis subminuta Krammer et e. reicHarDt, Tte. des Prat 25/05/05; (106–111) Encyonopsis sp. 2, Son Sant Joan 12/03/06; (112–117) Encyonopsis minuta Krammer et e. reicHarDt, Tte. de Son Vic 19/05/05; (118–123) Encyonopsis krammeri e. reicHarDt, Font des Pí 13/05/06; (124–129) Encyonopsis minuta Krammer et e. reicHarDt, Tte. des Prat 25/05/05. Scale bar 10 µm. commonly found in calcareous Mediterranean rivers (gomà et al. 2004; farrés et al. 2007). Cymbella lange–bertalotii Krammer (Figs 99–100; 166–169) was identiied in two seasons, and our photographs it with the specimens from Austria, Germany, Hungary and Russia presented by Krammer (2002). Although this species is very similar to Cymbella helvetica KütziNg and C. subhelvetica Krammer, its frustules are smaller than in C. helvetica and wider than in C. subhelvetica. Tte. de Deià had high percentages of Achnanthidium minutissimum, A. pyrenaicum and Encyonopsis minuta, and had similar values of electric conductivity, calcium, potassium, chlorine and sodium to Tte. des Prat (Table 2). The most remarkable fact is the presence of an undescribed species of the genus Cymbopleura that also appeared in Tte. des Prat. Springs The two springs studied, Font des Pí and Font de s’Olla, were sampled in four dates (Table 1). The benthic diatom community at Font des Pí was dominated by Denticula tenuis KütziNg, Encyonopsis krammeri, Achnanthidium pyrenaicum (Figs 170–179; 189–190), A. minutissimum, Diadesmis contenta (gruNoW ex vaN HeurcK) D.g. maNN and Navicula reichardtiana laNge–Bertalot (Figs 184–188). The presence of a new species for the Balearic Islands such as Navicula subalpina e. reicHarDt (Fig. 19) is also remarkable. Font de s’Olla was dominated by A. minutissimum, Diadesmis contenta (Figs 180–183) and Planothidium frequentissimum (Figs 14–18) in November, while in March the community was dominated by A. minutissimum. Diadesmis contenta, a typical aerophilous taxon, was present in both springs indicating seasonal dryness in these systems (caNtoNati et al. 2006; gesiericH & Kofler 2010). Taxonomic section Four species that did not it well with the species already described in the literature were found: Cymbopleura sp., Encyonopsis sp. 1, Encyonopsis sp. 2 and Fragilaria sp., but description of new taxa, based only on one or a very few cells, has been criticized. We are also considering this approach to be unproductive and possibly erroneous by omitting the whole range of morphological variation from the population in question. For this reason we propose only one new species of the genus Cymbopleura in this study and we used the material of the Tte. de Deià, where this species was more abundant. 98 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams obtusely rounded. Length 19–37 µm, width 6.5–9.0 µm, length/width ratio varying between 2.7 and 4.4; striae in the middle portion (dorsal) 11–12/10 µm, up to 13 towards the ends and puncta 40–45 in 10 µm (Table 4). Axial area narrow, curved, slightly ventrally displaced. Raphe distinctly lateral, narrowing towards the distal ends, appearing reverse–lateral near the proximal ends and terminal issures dorsally delected. Etymology: The new species is dedicated to Prof. Dr. Ramón Margalef (Barcelona, 1919–2004), in recognition of his extraordinary contributions to the limnological studies in the Balearic Islands. Holotype (hoc designatus): National Botanic Garden, Meise, Belgium (BR–4198). Isotype: British Museum of Natural History, London (BM–101403). Figs 130–141. LM : (130–135) Gomphonema lateripunctatum e. reicHarDt et laNge–Bertalot, Tte. des Prat 15/05/06; (136– 139) Gomphonema pumilum (gruNoW) e. reicHarDt et laNge– Bertalot, Font de s’Olla 13/03/06 ; (140–141) Gomphonema micropus KütziNg, Font de s’Olla 13/03/06; Scale bar 10 µm. Cymbopleura margaleii C. delgado, noVaIs, s. blanco et ector sp. nov., Figs 191–199 (LM), Figs 200–204 (SEM) Diagnosis: Valvae distincte dorsiventrales latae asymmetrice elliptico–lanceolatae, marginibuse dorsali arcuata, margine ventrali leviter convexa, apicibus late rotundatis. Longitudo 19–37 µm, latitudo 6.5–9.0 µm, ratio longitudo/latitudo circiter 2.7–4.4. Area axialis angusta curvata leviter ventraliter locata. Raphe distincte lateralis iliformis ad apices, reverse– lateralis ad aream centralem. Extrema proximalia leviter expansa ad poros centrales. Fissurae terminales dorsaliter delexae. Striae dorsales 11–12 in 10 µm in medio, usque ad 13 ad apices. Puncta 40–45 in 10 µm. Species nova dedicata est ad honorem Prof. Dr. Ramón Margalef (1919–2004) vir illustris in scientia hydrobiologica. Locus typicus: Deià torrentis, Maiorica Insula, Hispania (39º44’49’’N; 2º38’31’’E). Coll. Cristina Delgado in 22/05/2006. Description: Valves distinctly dorsiventral, broad, asymmetrically elliptical–lanceolate, with arcuate dorsal margin and slightly convex ventral margin, ends This new species was already described in DelgaDo (2011). Since this dissertation does not include an ISBN, the name of any printer, publisher or distributor, or any statement that it was intended to be effectively published under the requisites of the ICN (see art. 30.8) the description provided in this paper thus validates this taxon. Differential diagnosis: The new species is distinguished from the other taxa of the Cymbopleura austriaca (gruNoW) Krammer group by outline, length and width (Table 4). Krammer (2003) deined this group as presenting smaller valves with rhomboid–lanceolate outline and strongly reverse–lateral raphe. The valves of Cymbopleura margaleii may be confused, in the irst instance, with C. laeviformis Krammer or C. pyrenaica le coHu et laNge–Bertalot; nevertheless these species have a different outline and size (see Krammer 2003; le coHu et al. 2011). Cymbopleura margaleii is smaller and narrower than C. korana Krammer, C. rhomboidea var. angusta Krammer and C. laeviformis, with also denser puncta than the latter species (Table 4). Even though C. margaleii has a similar range of size as C. pyrenaica, the new species presents denser striae, coarser areolae and different shape of the areolae in both external and internal views (Table 4). Distribution: Thus far, only reported from alkaline and eutrophic springs in Majorca Island (Spain). New records: According to biogeographical theories, lower taxa richness is expected in isolated ecosystems such as islands. This is the case of the Hawaiian Islands, where the freshwater diatom lora is species poor and contains only 1.3% of endemic taxa (fuNglaDDa et al. 1983). However, islands frequently exhibit unusual diatom communities (e.g. moser et al. 1998; metzeltiN & laNge–Bertalot 2000). From a biogeographical point of view, the described diatom communities show low loristic singularities with respect to those described in the Iberian Peninsula and comparable European regions. After the revision of the bibliography and with the data collected during the present study, we can state Fottea, Olomouc, 13(2): 87–104, 2013 99 Figs 142–169. SEM : (142–144) Encyonopsis subminuta Krammer et e. reicHarDt, Tte. des Prat 25/05/05; (145, 146, 159, 161) Encyonopsis krammeri e. reicHarDt, Font des Pí 13/05/06; (147–149) Encyonopsis sp. 1, Tte. des Prat 25/05/05; (150) Gomphonema lateripunctatum e. reicHarDt et laNge–Bertalot, Tte. des Prat 15/05/06; (151–154) Cymbella vulgata Krammer, Tte. des Prat 25/05/05; (155–158) Encyonopsis cesatii (raBeNHorst) Krammer, Tte. des Prat 25/05/05; (160, 163–164) Encyonopsis minuta Krammer et e. reicHarDt, (160, 164) Tte. de Son Vic 19/05/05, (163) Font des Pí 13/05/06; (165) Gomphonema micropus KütziNg, Font de s’Olla 13/03/06; Cymbella lange–bertalotii Krammer, Tte. des Prat 25/05/05. Scale bars 10 µm (Figs 142, 145–147, 150–151, 158, 161–166), 5 µm (Figs 143–144, 148–149, 152, 154– 157, 167, 169), 1 µm (Figs 153, 159–160, 168). that 309 diatom taxa have been reported to date from the Balearic Islands, this paper adding 22 new records for the region (Appendix 1). The relatively large amount of loristic novelties could be explained by the lack of published works on diatoms from these islands. Several common taxa for the European lora have not been previously cited in Balearic Islands due to the scarcity of studies or because some of the taxa only have been recently described or separated from older species complexes such as Cymbella lange–bertalotii and C. vulgata (Krammer 2002), Diploneis separanda (Werum & laNge–Bertalot 2004), Encyonopsis krammeri, E. minuta, E. subminuta (Krammer 1997b) and Navicula antonii laNge–Bertalot et rumricH (laNge–Bertalot 1993). To our knowledge, the present study constitutes the irst record of Navicula wygaschii and Diploneis krammeri laNge–Bertalot et e. reicHarDt for the Iberian Peninsula (Spain and Portugal). The photographs of D. separanda for Majorca Island are the irst in Spain; it was irst recorded in a spring of the river Schutter (Franconia/Bavaria) and found in many other oligosaprobic waters of Germany by Werum & laNge–Bertalot (2004), later also in springs of Łódź Hills (Central Poland) by Żelazna–Wieczorek (2011). Gomphonema rosensto-ckianum laNge–Bertalot et e. reicHarDt has so far only been found in the Canary Islands (La Gomera, Tenerife), South Portugal, Balearic Islands, Duero Basin (Spain), and Cyprus (laNge–Bertalot 1993; Novais et al. 2009; BlaNco et 100 DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams Figs 170–190. LM: (170–179) Achnanthidium pyrenaicum (HusteDt) H. KoBayasi, Font des Pí 15/05/06; (180–183) Diadesmis contenta (gruNoW ex vaN HeurcK) D.g. maNN, Font des Pí 18/03/06; (184–188) Navicula reichardtiana laNge–Bertalot, Font des Pí 18/03/06. SEM: (189–190) Achnanthidium pyrenaicum (HusteDt) H. KoBayasi, Font des Pí 15/05/06. LM scale bar 10 µm, SEM scale bar 5µm. al. 2010; Kermarrec et al. 2011). According to fogeD (1984), spring environments have no speciic diatom loras; though taxa richness can be one of the largest within European freshwaters. The study by Werum & laNge–Bertalot (2004) in German springs reaches analogue conclusions. However, KaczmarsKa & rusHfortH (1983) detected several diatom taxa with disjunct geographical distribution patterns in certain North American springs. Likewise, diatoms in Sardinian springs have a remarkable degree of endemicity (laNge–Bertalot et al. 2003). This study contributed to improve the knowledge of the diatom lora in Majorca and the Balearic Islands, also providing a recent taxonomical overview on the modern benthic diatom lora of Majorca. It also adds information related to the physical and chemical factors and diatom communities, to previous works done in the island, being the irst study on epilithic diatoms from springs in the Balearic Islands. acKnowledgMents This article covers some of the results obtained in the context of a project dealing with the application of the Water Framework Directive in Balearic Islands. The inancial support for this study has been provided by Agència Balear de l’Aigua i de la Qualitat Ambiental and this also included the support of the University of Vigo (Spain) and the Centre de Recherche Public – Gabriel Lippmann (Luxembourg). We are grateful to the editor and anonymous reviewers for their criticism and comments that improved the inal manuscript. We thank Liliana García for the help with the sample collection, M. Dominguez with the chemical analysis, Gabriel Moyà with the bibliography of Balearic Islands and Christophe Bouillon with the SEM micrographs. Dr. Maria Angélica Oliveira (Universidade Federal de Santa Maria, Brazil) kindly revised the English. references Figs 191–199. LM: (191–199) Cymbopleura margaleii c. DelgaDo, Novais, s. BlaNco et ector sp. nov.; (191–195) Tte. des Prat 25/05/05; (196–199) Tte. de Deià 22/05/06, type material (Fig. 198 designated as holotypus). Scale bar 10 µm. aBoal, m.; Prefasi, m. & aseNcio, m.D. (1996): The aquatic microphytes and macrophytes of the Transvase Tajo–Segura irrigation system, southeastern Spain. – Hydrobiologia 340: 101–107. aBoal, m.; Álvarez–coBelas, m.; camBra, j. & ector, l. (2003): Floristic list of the non–marine diatoms (Bacillariophyceae) of Iberian Peninsula, Balearic Islands and Canary Islands. Updated taxonomy and bibliography. – Diatom Monogr. 4: 1–639. alvarez coBelas, m. & estévez garcía, a. (1982): Catálogo de las algas continentales españolas. I. Diatomophyceae Rabenhorst 1864. – Lazaroa 4: 269–285. aPHa (1995): Standard methods for the examination of water and wastewater. – AWWA, WEF. 19th ed. New York, American Public Health Association. BlaNco, s.; cejuDo–figueiras, C.; Álvarez–BlaNco, I.; Bécares, E.; HoffmaNN, L. & ector, L. (2010): Atlas de las Diatomeas de la cuenca del Duero, Diatom atlas of the Duero Basin., 1a ed. – 382 pp., Área de Publicaciones, Universidad de León, León. camBra, j.; saBater, s. & tomÁs, X. (1991): Diatom check– list from Catalonian countries (Eastern Spain). – Bull. Inst. Catalana Hist. Nat. 59, Secc. Bot. 8: 5–39. Fottea, Olomouc, 13(2): 87–104, 2013 101 Figs 200–204. SEM: (200–204) Cymbopleura margaleii c. DelgaDo, Novais, s. BlaNco et ector sp. nov.; (200–201, 203–204) Tte. de Deià 22/05/06, type material, (203) Tte. des Prat 25/05/05. Scale bars 5 µm (Figs 200–203), 1 µm (Figs 204–205). C. margaleii sp. nov C. korana 102 Table 4. Morphological characterization of Cymbopleura margaleii and closely related Cymbopleura taxa. C. rhomboidea var. angusta C. laeviformis C. pyrenaica Valve outline distinctly dorsiventral; asymdistinctly dorsiventral; broadly moderately to distinctly dormetrically elliptical–lanceolate subelliptical to elliptical–lansiventral; broadly rhomboid– ceolate lanceolate distinctly dorsiventral; asymdistinctly dorsiventral; semi– metrically elliptical–lanceolate lanceolate to rhomboid lanceolate Valve ends obtusely rounded obtusely rounded obtusely rounded obtusely rounded obtusely rounded, not protracted Length (mm) 19–37 31–59 23–58 27–46 13.8–39 Width (mm) 6.5–9 11–13 10–13 8.5–10.7 5.6–9.5 4.4 4.6 4.2 4.3 4.2 Areolae / 10 mm 11–12 9–10 8–10 11–13 12–17 40–45 29–32 30–36 30–35 35–40 Morphology of the areolae in external view (SEM) linear – – quadrangular reniform, cruciform, triphid Morphology of the areolae in internal view (SEM) quadrangular, with papillas on the top and bottom of the space between two areolae – – four ine ribs surrounding each ine ribs oblique over the viareola mines DelgaDo et al.: Epilithic diatoms of springs and spring–fed streams Maximum L/B ratio Striae / 10 mm Fottea, Olomouc, 13(2): 87–104, 2013 caNtoNati, m.; gerecKe, r. & Bertuzzi, e. 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(2011): Diatom lora in springs of Łódź Hills (Central Poland). Biodiversity, taxonomy, and temporal changes of epipsammic diatom assemblages in springs affected by human impact. – Diatom Monogr. 13: 1–419. Supplementary material the following supplementary material is available for this article: Appendix 1. Diatom checklist of Balearic Islands (*new record for Balearic Islands and **new record for Spain). Underlined the taxa identiied in the present study. This material is available as part of the online article (http://fottea.czechphycology.cz/contents) © Czech Phycological Society (2013) Received November 30, 2012 Accepted February 12, 2013