Morphology and distribution of some marine diatoms, family Rhizosoleniaceae, genus Proboscia, Neocalyptrella, Pseudosolenia, Guinardia , and Dactyliosolen in Korean coastal waters
- Author: Yun Suk Min, Lee Jin Hwan
- Organization: Yun Suk Min; Lee Jin Hwan
- Publish: ALGAE Volume 26, Issue4, p299~315, 30 June 2011
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ABSTRACT
The morphology, taxonomy, and distribution of species belonging to the diatom family Rhizosoleniaceae were stud-ied from the marine coastal waters of Korea. Rhizosolenid diatom taxa were collected at 30 sites from September 2008 to February 2010 and were analyzed by light and scanning electron microscopy. We identified 6 rhizosolenid genera, including
Rhizosolenia, Proboscia, Pseudosolenia, Neocalyptrella, Guinardia , andDactyliosolen . We describe 5 genera in this study, exceptRhizosolenia . Five genera were compared in detail with congeneric species. Six genera within the fam-ily Rhizosoleniaceae were divided into two groups based on morphological diagnostic characters including valve shape, areolae pattern, the shape of external process, and girdle segments in the column. The first group had a conoidal valve and loculate areolae, which comprisedRhizosolenia, Proboscia, Pseudosolenia , andNeocalyptrella , and the second group ofGuinardia andDactyliosolen showed a flat or rounded valve and poroid areolae. Important key diagnostic characters were based on valve shape, areolae pattern on the segment, external process, position of the tube, and the valve margin.D. phuketensis was new to Korean coastal waters.
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KEYWORD
Dactyliosolen , diatoms , distribution , Guinardia , morphology , Neocalyptrella , Proboscia , Pseudosolenia , Rhizosolenia
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Peragallo (1892) regarded the genera
Dactyliosolen Castracane,Lauderia Cleve,Attheya T. West,Guinardia H. Peragallo, andRhizosolenia Brightwell as members of Rhizosoleniees. Thereafter, Hustedt (1930) suggested that 23 marine and 4 freshwater species belonged to this family. He synonymized several species, as several ear-lier studies described variations of seemingly the same species.Sundstrom (1986) suggested that only those species with valves bearing an external process, otaria, claspers, and copulae perforated by loculate areolae should be included in the genus
Rhizosolenia . According to Sund-strom (1986), the genusProboscia Sundstrom andPseu-dosolenia Sundstrom were separated fromRhizosolenia because they have external processes. The two species ofR. calcar-avis Schultze andR. alata Brightwell were subsequently transferred toPseudosolenia calcar-avis Sundstrom andProboscia alata Sundstrom, respectively (Sundstrom 1986).R. robusta Norman was also trans-ferred toNeocalyptrella robusta Hernandez-Becerril and Meave (Hernandez-Becerril and Meave del Castillo 1996, 1997).More recently, the family Rhizosoleniaceae included
Neocalyptrella, Pseudosolenia, Proboscia , andUrosolenia . Representatives of these genera are commonly found as solitary cells in marine environments, exceptUrosolenia , which is restricted to freshwater (Edlund and Stoermer 1993, Rott et al. 2006, Li et al. 2009). The generaGuinardia andDactyliosolen have been allocated to the family Rhi-zosoleniaceae.In Korea, the genera
Rhizosolenia, Guinardia , andDac-tyliosolen were recorded by Shim (1994). Many authors (Moon and Choi 1991, Yoon et al. 1992, Chang and Shim 1993, Kim et al. 1993, Yoon and Koh 1994, 1995) and Lee (1995) addedPseudosolenia andProboscia to his check-list. Additional studies on the family Rhizosoleniaceae in Korea have been conducted sporadically (Yun and Lee 2010, Yun et al. 2011), but species identification, synon-ymies, and the phylogeny the family Rhizosoleniaceae have been insufficiently investigated. The present study provides a detailed survey of marine diatoms belonging to the generaProboscia, Pseudosolenia, Neocalyptrella, Guinardia , andDactyliosolen from the coastal waters of Korea. This survey provides detailed light and scanning electron microscopy illustrations and a critical review of the taxonomical and distributional data.Field samples were collected in Korean coastal waters from September 2008 to February 2010 (Table 1). Phyto-plankton was collected using a 20 μm mesh-sized net by vertical towing. Samples were immediately fixed in neu-tralized formalin (final concentration 4%), glutaraldehyde (final concentration 2%), and Lugol’s solution. Organic material in the samples was removed using the methods of Hasle and Fryxell (1970) and Simonsen (1974). The ma-terials were examined under a light microscope (Axios-kop 40; Carl Zeiss, Jena, Germany), photographed with a MRc5 camera (Carl Zeiss) and a scanning electron micro-scope (JSM-5600LV; Jeol, Tokyo, Japan). Sizes of cells were measured using image calculation software (AxioVision AC v. 4.5; Carl Zeiss).
Terminology was from that recommended in the first report of the working Committee on Diatom Terminol-ogy (Anonymous 1975) from the third Symposium on Recent and Fossil Marine Diatoms, Kiel. Other terminol-ogy follows Ross et al. (1979), Sundstrom (1986), Round et al. (1990), Hernandez-Becerril (1995), and Hasle and Syvertsen (1996).
We identified 6 rhizosolenid genera, including
Rhizo-solenia, Proboscia, Pseudosolenia, Neocalyptrella, Guinar-dia , andDactyliosolen . We described five of these genera exceptRhizosolenia . The morphological characters ob-served in the generaProboscia, Neocalyptrella, Pseudoso-lenia, Dactyliosolen , andGuinardia species are shown in Table. 2-4. According to the system suggested by Sund-strom (1986), 9 phytoplanktonic diatom taxa represent-ing 1 order, 1 suborder, 1 family, 5 genera, and 9 species were identified in this study. The systematic accounts are as follows:Class Bacillariophyceae Haeckel 1878Order Centrales Hustedt 1930
Suborder Rhizosoleniineae Simonsen 1979
Family Rhizosoleniaceae De Toni 1890
Genus Proboscia Sundstrom 1986
Proboscia alata (Brightwell) Sundstrom 1986
Proboscia indica (H. Peragallo) Hernandez-Becerril 1995
Genus Neocalyptrella (Norman) Hernandez-Becerril & Meave 1996
Neocalyptrella robusta Hernandez-Becerril & Meave 1996
Genus Pseudosolenia Sundstrom 1986
Pseudosolenia calcar-avis (Schultze) Sundstrom 1986
Genus Guinardia H. Peragallo 1892
Guinardia delicatula (Cleve) Hasle 1995
Guinardia flaccida (Castracane) H. Peragallo 1892
Guinardia striata (Stolterforth) Hasle 1995
Genus Dactyliosolen Castracane 1886
Dactyliosolen fragilissimus (Bergon) Hasle 1995
Dactyliosolen phuketensis (Sundstrom) Hasle 1995
> Proboscia alata (Brightwell) Sundstrom 1986 (
Fig. 1 , A-H)Brightwell 1858, p. 95, Pl. 5, Fig. 8; Peragallo 1892, p. 115, Pl. 18, Fig. 11-20; Hustedt 1920, Pl. 317; Hustedt 1930, p. 600, Fig. 345; Cupp 1943, p. 90, Fig. 52A & B; Oku-no 1952, p. 353, Pl. 2, Fig. 5 & 6; Okuno 1960, p. 310, Pl. 1, Fig. 1; Hendey 1964, p. 146, Pl. 2, Fig. 2; Drebes 1974, p. 57, Fig. 39c & d; Navarro 1981, p. 430, Fig. 33 & 34 as R. alata; Sundstrom 1986, p. 99, Fig. 258-266; Jordan et al. 1991, p. 65, Fig. 1-9; Takahashi et al. 1994, p. 413, Fig. 2-7; Hernandez-Becerril 1995, p. 252, Fig. 2-4; Hasle and Syvertsen 1996, p. 159, Pl. 30; Sunesen and Sar 2007, p. 639, Fig. 82-88 & 98.
Synonyms .Rhizosolenia alata Brightwell 1858,Rhizo-solenia alata f.gracillima (Cleve) Gran 1905.Cells are solitary or in pairs, narrow cylindrical, bilat-erally symmetrical, 3.3-13.3 μm in diameter, 270.0-485.7 μm long. Valve is sub-conoidal, the ventral part longer than the dorsal part and proboscis structure is slightly curved, tapering towards the apical part of the valve, cir-cular in cross section, 15.0-30.0 μm long. Apical surface of the proboscis is composed of variously sized spinules. Number of spinules is 7-16, 0.1-0.4 μm long. Contiguous area is convex towards the valve surface, distally limited by asymmetric claspers. The valve areolae are rounded, 52-90 in 10 μm, arranged in longitudinal striae, converg-
ing towards the apex. Girdle segment areolae are loculate, arranged in columns, with the external velum perforated by central pores, and internal circular foramina, 25-62 in 10 μm. Interlocular pores are commonly surrounded by six loculi. Segment horizontal axis and perpendicular axis are 3.3-13.3 and 10.0-26.7 μm long, respectively.
Distribution .Proboscia alata has frequently been re-ported in the Argentine Sea (Ferrario and Galavan 1989 asR. alata andR. alata f.gracillima ). During this study,P. alata was frequently observed in September 2008 and June 2009 at the Wolsung coast, Jeju Island, and the Korea Strait.Remarks . Sundstrom (1986) did not share the biogeo-graphical limits ofP. alata because synonyms were used for probably all taxa included in the genus. The specificlimits of the taxa including
Proboscia have been deter-mined by many authors (Jordan and Priddle 1991, Jordan et al. 1991, Takahashi et al. 1994, Jordan and Saito 1999, Jordan and Ito 2002, Jordan and Ligowski 2004, 2006). Takahashi et al. (1994) reported that the genus contains five modern species distributed from polar to temperate regions. Jordan and Ligowski (2004) stated thatP. alata is not cosmopolitan, because it appears to be a com-plex cryptic species. SomeP. alata representatives are commonly found in polar waters. However, Hernandez-Becerril (1995) found thatP. alata is distributed from tropical to subtropical waters.> Proboscia indica (Peragallo) Hernandez-Becerril emend. Jordan & Ligowski 1995 (
Fig. 2 , A-F)Hustedt 1930, p. 602, Fig. 346; Cupp 1943, p. 93, Fig. 52C; Hendey 1964, p. 147, Pl. 2, Fig. 4; Hernandez-Becerril 1995, p. 254, Fig. 5 & 6; Moreno et al. 1996, p. 15, Pl. 29, Fig. 6 & 7; Jordan and Ligowski 2004, p. 98, Pl. 4, Fig. 5-7; Gomez and Souissi 2007, p. 287, Fig. 4g-h; Sunesen and Sar 2007, p. 639, Fig. 89-97 & 99.
Synonyms .Rhizosolenia indica H. Peragallo 1892,Rhi-zosolenia alata f.indica (Peragallo) Gran 1905.Cells are solitary or in pairs, cylindrical, bilaterally symmetrical, 25.0-125.0 μm in diameter, 193.4-764.2 μm long. Valve is sub-conoidal, the ventral part longer than the dorsal part. Proboscis structure is strongly curved, ta-pered towards the apical part in the valve, circular in cross section, 39.0-83.3 μm long. Apical surface of the proboscis is composed of varied sized spinules and the slit is pore shape situated below the apex. Spinule number is 8-13 and 0.2-0.5 μm long. Contiguous area is convex towards the valve surface, distally limited by asymmetric claspers. The valve areolae are rounded, 30-60 in 10 μm, arranged in longitudinal striae, converging towards the apex. Gir-dle segment areolae are loculate, arranged in columns, and the external velum is perforated by central pores and internal circular foramina. Interlocular pores are com-monly surrounded by four loculi. The horizontal axis of the segments is 25.0-125.0 μm and the perpendicular axis is 10.6-16.0 μm.
Distribution . Hendey (1964) reported thatP. indica is common in temperate and sub-tropical seas asR. alata var.indica . This species has been reported from Buenos Aires marine waters (Marques Da Cunha and Da Fonseca 1917, Balech 1964, 1971, 1979, Lange 1985 asR. alata var.indica ). During the present study,P. indica was rare but distributed widely at Geoje Island, Daebu Island, Dae-cheon Harbor, the Yangyang coast, and the Yellow Sea from September 2008 to October 2009.Remarks .Proboscia indica andP. alata are fairly simi-lar species. However,P. indica differs fromP. alata by the larger diameter of the frustule and valve morphology. The valve shape ofP. indica is sub-conical, round, and tapers into a strongly curved proboscis. Additionally, the pat-tern of the interlocular pores also differs between the two species, similar to a feature previously described by Hasle (1975) and Takano (1990).P. indica have interlocular pores surrounded by four loculae, but theP. alata inter-locular pores are surrounded by six loculae, as observed by Sundstrom (1986).> Neocalyptrella robusta (Norman) Hernandez-Becerril & Meave 1996 (
Fig. 3 , A-H)Pritchard 1861, p. 866, Pl. 8, Fig. 42; Peragallo 1892, p. 109, Pl. 14, Fig. 1; Hustedt 1920, Pl. 320, Fig. 1-3; Hustedt 1930, p. 578, Fig. 330; Cupp 1943, p. 83, Fig. 46; Okuno 1957, p. 105, Pl. 2, Fig. 1; Okuno 1968, Fig. 1(6), 10A, 17 & 18; Navarro 1981, p. 430, Fig. 43 & 45; Sundstrom 1986, p. 104, Fig. 289 & 290 as
R. robusta ; Hernandez-Becerril and Meave del Castillo 1996, p. 199, Fig. 1-20 asCalyptrella robusta ; Hasle and Syvertsen 1996, p. 159, Pl. 30 asR. ro-busta ; Gomez and Souissi 2007, p. 287, Fig. 4i; Sunesen and Sar 2007, p. 637, Fig. 62-67.Synonyms .Rhizosolenia robusta Norman in Pritchard 1861,Calyptrella robusta (Norman) Hernandez-Becerril and Meave 1996.Cells are solitary, large, bilaterally symmetrical, 108.3-190.6 μm in diameter, 413.3 μm long, elliptical in cross sec-tion, crescent shaped in lateral view and of sigmoid form in ventro-dorsal view. Valve is conoidal with a rounded or truncated apex and with longitudinal undulations. Pro-cess is a cylindrical external tube, straightened towards the distal part, merging with the calyptra structure and circular pore in the distal part of the tip, 6.7-7.3 μm long, 0.8-1.0 μm in diameter. Valve areolae, 13-16 in 10 μm, are arranged in regularly straight striations, with a secondary quincuncial pattern. Otaria, claspers, and contiguous ar-eas are absent. Girdle segments are oriented in a straight line and arranged in two dorsiventral columns. Segment areolae, 17-22 in 10 μm, are arranged in regular, straight striations, with a secondary quincuncial pattern, loculate areolae, with the velum perforated by slit-like pores and internal foramina, circular to subcircular. Horizontal axis and perpendicular axis of segments are 108.3-190.6 and 11.7-25.0 μm in length, respectively.
Distribution .Neocalyptrella robusta is distributed from tropical to temperate waters (Hasle and Syvertsen 1996, Hernandez-Becerril and Meave del Castillo 1996). It has been reported to occur in littoral Argentinean wa-ters (Ferrario and Galavan 1989, asRhizosolenia robusta ). During this study,N. robusta was rare but observed in September 2008 and June 2009 at Geoje Island, the Korea Straight, the Wolsung coast, and the Yellow Sea.> Pseudosolenia calcar-avis (Schultze) Sundstrom 1986 (
Fig. 4 , A-H)Schultze 1858, p. 339, Pl. 13, Fig. 5-10; Peragallo 1892, p. 113, Pl. 17, Fig. 9; Hustedt 1930, p. 592, Fig. 339 as
R. cal-car-avis ; Cupp 1943, p. 89, Fig. 51 asR. calar-avis ; Navarro 1981, p. 430, Fig. 36 & 37 asR. calcar-avis ; Sundstrom 1986, p. 95, Fig. 40-46 & 247-257; Hernandez-Becerril 1995, p. 254, Fig. 7-10; Hasle and Syvertsen 1996, p. 160, Pl. 30; Sunesen and Sar 2007, p. 637, Fig. 68-81.Synonym .Rhizosolenia calcar-avis Schultze 1858.Cells are usually solitary, elongated, of cylinder shape, bilaterally symmetrical, circular in cross section, 9.3-90.0 μm in diameter, 206.7-793.8 μm long. Valve is sub-conical, asymmetrical, with the ventral part slightly longer than the dorsal part. Contiguous area is a narrow groove, sig-moid, extended from the basal part of the process to the margin in the ventral part of the valve. Process is claw or screw shaped, slightly or strongly curved, and tapered towards the distal part, 10.7-51.4 μm long. Otaria and claspers are absent. Valve areolae are poroid, circular, 16-34 in 10 μm. Striations are regular and straight, with a secondary quincuncial pattern. Girdle segments are scale-shaped to rhomboidal, arranged in two or multiples of two columns, with a sub marginal seam-like structure close to the advalvar margin with entire hyaline edges. Horizontal axis and perpendicular axis of segments are 9.3-90.0 and 9.3-46.2 μm long, respectively. Segmented areolae are 21-38 in 10 μm in a secondary quincuncial pattern.
Distribution .Pseudosolenia calcar-avis is a circum-globally distributed species (Sundstrom 1986) and occurs in warm waters and occasionally in temperate waters (Hasle and Syvertsen 1996). It has been reported several times in both oceanic and near-shore waters along the coastline of Argentina (Ferrario and Galavan 1989, asRhizosolenia calcar-avis ). In the present study, this spe-cies was rarely observed in September 2008 to September 2009 in the oceanic waters of Jeju Island and the Yellow Sea.> Guinardia delicatula (Cleve) Hasle 1995 (
Fig. 5 , A & B)Cleve 1900, p. 28, Fig. 11; Hustedt 1930, p. 577, Fig. 328; Cupp 1943, p. 83, Fig. 44; Hendey 1964, p. 147, Pl. 4, Fig. 2; Drebes 1974, p. 49, Fig. 35a; Sundstrom 1986, p. 103, Fig. 272 & 273.
Basionym .Rhizosolenia delicatula Cleve 1900.Cells form fairly straight chains and are bilaterally sym-metrical. Cells are 7.9-13.2 μm in diameter, 24.9-30.0 μm in length. Valve margins are round. External process is thin and short, and narrow, tube-shaped, and oblique to the pervalvar axis. External processes are 2.1-5.0 μm long. External process fits into a depression on the adjacent valve. Girdle segments are composed of open bands, with poroid areolae, and are not noticeable. Segment horizon-tal axes are 7.9-13.2 μm long.
Distribution . Hasle and Syvertsen (1996) reported thatG. delicatula is a cosmopolitan species in temperate and tropical waters. During the present study, this species was recorded in July 2009 and January 2010 in the coastal wa-ters of Sacheon, Incheon, and Mokpo.> Guinardia flaccida (Castracane) H. Peragallo 1892 (
Fig. 5 , C-E)Castracane 1886, p. 74, Pl. 29, Fig. 4; Peragallo 1892, p. 107, Pl. 1, Fig. 3-5; Bergon 1903, p. 78, Pl. 2, Fig. 1-3; Hustedt 1930, p. 562, Fig. 322; Cupp 1943, p. 78, Fig. 40; Hendey 1964, p. 147, Pl. 5, Fig. 5; Drebes 1974, p. 58, Fig. 43a; Hasle 1975, p. 116, Fig. 64, 65 & 81-89; Navarro 1981,
p. 430, Fig. 31 & 32; Takano 1990, pp. 260-261.
Basionym .Rhizosolenia flaccida Castracane 1886.Cells are solitary or form fairly straight chains, and are bilaterally symmetrical. Cells are 14.0-42.5 μm in diame-ter, 50.0-125.0 μm in length. Valves are flat or slightly con-cave. External processes are short and tube-shaped. Short tube-shaped external processes are located on the exter-nal valve surface. External processes are 1.5-1.8 μm long. Girdle segments composed of open bands with poroid areolae. The segment horizontal axis and perpendicular axis are 14.0-42.5 and 1.3-5.0 μm in length, respectively.
Distribution .Guinardia flaccida shows a cosmopoli-tan distribution except the two polar bodies of water (Hasle and Syvertsen 1996). During the present study,G. flaccida was frequently observed in September 2008 and August 2009 in the coastal waters of the Yellow Sea, Geoje Island, Namhae, Sacheon, Tongyeang, and Incheon.> Guinardia striata (Stolterforth) Hasle 1995 (
Fig. 5 , F-H)Stolterforth 1879, p. 836, Fig. a & b; Peragallo 1888, p. 82, Pl. 6, Fig. 44; Peragallo 1892, p. 108, Pl. 13, Fig. 17 & 18; Bergon 1903, p. 57, Pl. 1, Fig. 1-8; Hustedt 1920, Pl. 320, Fig. 4 & 5; Hustedt 1930, p. 578, Fig. 329; Cupp 1943, p. 83, Fig. 45; Hendey 1964, p. 148, Pl. 4, Fig. 5; Drebes 1974, p. 49, Fig. 35b; Hasle 1975, p. 113, Fig. 66-73; Sundstrom 1980, p. 580, Fig. 2-4; Navarro 1981, p. 430, Fig. 48 as
R. stolterforthii ; Sundstrom 1986, p. 103, Fig. 274 & 275; Von Stosch 1986, p. 319, Fig. 13 & 14; Hernandez-Becerril 1995, p. 262, Fig. 53-56.Basionym .Rhizosolenia stolterforthii (Stolterforth) H. Peragallo 1888.Cells form curved chains, rarely spiraling chains, and are bilaterally symmetrical. Cells are 10.0-20.0 μm in diameter, and 50.0-120.0 μm in length. Valve flat and rounded at margin. External processes are thin, and hook-shaped to the pervalvar axis, and the external pro-cesses are 4.3-6.7 μm long. External process fits into a de-pression on the adjacent valve. Girdle bands composed of open bands with poroid areolae. Segment horizontal axis and perpendicular axis are 10.0-20.0 and 4.3-4.6 μm long, respectively.
Distribution .Guinardia striata is cosmopolitan, but it does not occur in polar bodies of water (Hasle and Sy-vertsen 1996). During the present study,G. striata was rarely observed in September 2008 and August 2009 in the coastal waters of Namhae, Daebu Island, Incheon, and Yeongdeok.> Dactyliosolen fragilissimus (Bergon) Hasle 1995 (
Fig. 6 , A-D)Bergon 1903, p. 49, Pl. 1, Fig. 9 & 10; Hustedt 1930, p. 571, Fig. 324; Cupp 1943, p. 80, Fig. 41; Drebes 1974, p. 48, Fig. 34b & c; Hasle 1975, p. 114, Fig. 61, 62 & 74-78; Navarro 1981, p. 430, Fig. 38 as
R. fragilissima ; Sundstrom 1986, p. 103, Fig. 268 & 269; Takano 1990, pp. 262-263.Basionym .Rhizosolenia fragilissima Bergon 1903.Cells are cylindrical with rounded marginal parts, forming straight chains. Cells are connected in loose fit-ting chains at the center of the valve surface. Cells are 8.3-20.0 μm in diameter, and 25.0-33.4 μm in length. Valves are flat or convex at the central part. External process is a thin, oblique tube in the central part of the valve. External processes are 1.1-4.3 μm long and fit into a depression on adjacent cells. Girdle bands composed of half bands with poroid areolae.
Distribution .Dactyliosolen fragilissimus is probably cosmopolitan (Hasle and Syvertsen 1996) but was rarely observed in February 2010 in Goseong.Remarks . Cell length ofDactyliosolen fragilissimus varies from 30.0-80.0 μm (Gran and Angst 1931), 50.0-80.0 μm (Cupp 1943), 42.0-67.0 μm (Hendey 1964), and 42.0-300.0 μm (Hasle and Syvertsen 1996). During this study,D. fragilissimus was not observed with a length of pervalvar axis up to 100 μm.> Dactyliosolen phuketensis (Sundstrom) Hasle 1995 (
Fig. 6 , E-G)Sundstrom 1980, p. 579, Fig. 1-3; Sundstrom 1986, p. 103, Fig. 270 & 271; Von Stosch 1986, p. 323, Fig. 15-17; Hernandez-Becerril 1995, p. 262, Fig. 50-52.
Basionym .Rhizosolenia phuketensis Sundstrom 1980.Cells are cylindrical with a rounded marginal part, forming curved chains. Cells are connected in fairly fitting chains and are bilaterally symmetrical. Cells are 10.0-20.0 μm in diameter, and 31.3-129.2 μm long. Valves are flat or slightly convex. External process is usually an obtuse, short tube in the valve marginal part. External processes are 1.3-6.7 μm long and fit into a depression in adjacent cells. Girdle bands are composed of half bands with po-roid areolae. Segment horizontal axis and perpendicular axis are 10.0-20.0 and 1.3-6.6 μm in length, respectively.
Distribution . Sundstrom (1986) reported thatD. phuketensis occurs in warm water regions to temperate regions including the North Sea and Skagerrak. During this study,D. phuketensis was newly recorded in June 2009 and October 2009 from the coastal waters of Geoje Island, Sacheon, Tongyeang, Yeongduk, and the Yellow Sea.Remarks .Dactyliosolen phuketensis was recorded for the first time in Korean coastal waters, but this species was already observed a long time ago, resemblingG. stri-ata . Although the two species belonged to different gen-era and were recorded in Korean coastal waters, they can be easily misidentified using the curved cell and colony shape as discriminating characters. The external process shapes are different between two taxa. The external pro-cesses ofG. striata are hook shaped, whereas those ofD. phuketensis are short external tubes. The position of the external process is not the same, and segment (band) shape also differs. Representatives of the genusGuinar-dia are composed of an open band, but the genusDactyli-osolen is composed of a half band.The family Rhizosoleniaceae includes
Rhizosolenia, Proboscia, Pseudosolenia, Neocalyptrella, Guinardia, Dactyliosolen , andUrosolenia . The key morphological characters of the family Rhizosoleniaceae are cylindrical cells in solitary or chain form, unipolar and symmetrical valves, numerous chloroplasts, and a few resting spores. The genera within Rhizosoleniaceae are very common in the marine ecosystem and sometimes dominate the phytoplankton biomass in highly productive oceanic re-gions (Sundstrom 1986, Hernandez-Becerril and Meave del Castillo 1996, 1997). Some species of the family Rhi-zosoleniaceae are causative bloom organisms in various regions of the world (Jordan and Priddle 1991, Jordan et al. 1991, Takahashi et al. 1994). These species are very im-portant diatoms in marine environments.As shown in Table 2 of Yun and Lee (2010), Table 2 in Yun et al. (2011), and Table. 2-4 in the present study, we divided the 6 genera within the family Rhizosoleniaceae into two groups by morphological diagnostic characteris-tics including the shape of the external process and girdle segments in the column (Yun and Lee 2010, Yun et al. 2011). The first group had a conoidal valve and loculate areolae and was comprised of
Proboscia, Pseudosolenia, Rhizosolenia, Neocalyptrella , and the second group had a flat or rounded valve and poroid areolae and was ofGui-nardia andDactyliosolen . In the present study, 2 species belonged toProboscia , 3 species toGuinardia , 2 species toDactyliosolen , 1 species toPseudosolenia , and 1 species belonged toNeocalyptrella .Cell diameters of
Proboscia alata were 3.3-13.3 μm, but previous studies reported 7.0-18.0 μm (Cupp 1943 asRhi-zosolenia alata ), 8.5-11.5 μm (Sundstrom 1986), 2.5-42.0 μm (Jordan et al. 1991), 7.0-24.0 μm (Hernandez-Becerril 1995), 2.5-13.0 μm (Hasle and Syvertsen 1996), and 7.0-11.0 μm (Sunesen and Sar 2007). Cell diameters ofP. indi-ca were 25.0-125.0 μm. Our specimens closely resembled those described previously (Cupp 1943, Hernandez-Becerril 1995, Jordan and Ligowski 2004), but their cell diameters were smaller (16.0-73.0 μm) than those of our specimens. Cell diameters ofN. robusta (108.3-190.6 μm) andP. calcar-avis (9.3-90.0 μm) were smaller than those of Hasle and Syvertsen (1996) and Sunesen and Sar (2007), respectively.Cell diameters of
G. delicatula were 7.9-13.2 μm,G. flac-cida were 23.3-42.5 μm, andG. striata were 10.0-20.0 μm. No differences were observed in the 3 species cell diam-eters compared with those of many studies (Cupp 1943, Hernandez-Becerril 1995, Hasle and Syvertsen 1996).Cell diameters of
D. fragilissimus andD. phuketen-sis were 8.3-20.0 μm and 10.0-20.0 μm, respectively. Our specimens were similar to those of Hasle and Syvertsen (1996), but their cell diameters were wider than those of our specimens.External processes varied from short tube-shaped in
N. robusta andD. phuketensis , claw or screw-shaped inP. calcar-avis , narrow tube-shaped inG. delicatula , slight hook-shaped inG. striata , and oblique tube-shaped inD. fragilissimus . The genusProboscia was distinguished within the first group because the external processes were longer, and the valve was changed to a probosic structure. As the external process ofRhizosolenia was in the shape of a needle and tube, this genus is separated from other genera (Yun and Lee 2010, Yun et al. 2011). The external process of the family Rhizosoleniaceae is an important taxonomic key character.Areolae occurred in various forms on the external view; circular to sub circular pore-shaped in
P. alata, P. indica , andN. robusta and circular to slightly oval pore-shaped inPseudosolenia calcar-avis . We were unable to count the number of areolae inG. delicatula, G. striata, D. fragilis-simus , andD. phuketensis , but areolae ofD. phuketensis are slit-like with a parallel to pervalvar axis (Hernandez-Becerril 1995).The number of areolae in the valves varied from 52-90 in 10 μm in
P. alata , 30-60 in 10 μm inP. indica , 13-16 in 10 μm inN. robusta , and 16-34 in 10 μm inP. calcar-avis . Hasle and Syvertsen (1996) reported thatN. robusta (asRhizosolenia robusta ) had 19-20 in 10 μm and 28-32 in 10 μm inP. calcar-avis . Sunesen and Sar (2007) reported thatP. alata had 54 in 10 μm, 17 in 10 μm inN. robusta , and 23-32 in 10 μm inP. calcar-avis . No differences were observed from previous reports. The number of areolae in the seg-ments varied from 25-62 in 10 μm inP. alata , 17-22 in 10 μm inN. robusta , and 21-38 in 10 μm inP. calcar-avis .N. robusta has 24-26 in 10 μm (Hasle and Syvertsen 1996 asRhizosolenia robusta ), 22-23 in 10 μm inN. robusta , and 28-32 in 10 μm inP. calcar-avis (Sunesen and Sar 2007). Our specimens had a similar number of areolae in the segments compared with those of previous reports. We could not count number of areolae inP. indica, G. delicat-ula, G. flaccida, G. striata, D. fragilissimus , andD. phuke-tensis , because of delicate cells.Abundant distributions of
G. flaccida andP. indica were found in Korean coastal waters.G. flaccida was widely distributed at 6 stations, andD. fragilissimus andN. robusta were sporadically found at 4 stations in Korean coastal waters.P. calcar-avis has been frequently found in the Korean coastal waters, and this species is a warm and temperate water species (Cupp 1943, Hendey 1964, Sundstrom 1986, Hernandez-Becerril 1995, Hasle and Sy-vertsen 1996).Dactyliosolen phuketensis was new to Ko-rean coastal waters.-
[Table 1.] Sampling sites for the genera Proboscia, Neocalyptrella, Pseudosolenia, Guinardia, and Dactyliosolen of the family Rhizosoleniaceae
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[Table 2.] Morphological characteristics of the Proboscia species examined in this study
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[Table 3.] Morphological characteristics of the Pseudosolenia and Neocalyptrella species examined in this study
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[Fig. 1.] Proboscia alata. (A) A complete cell, light microscopy (LM). (B) A complete cell, scanning electron microcopy (SEM). (C) Apical part of the valve, noticeable clasper (arrow), LM. (D) Apical part of valve, noticeable clasper (arrow), SEM. (E) Details of proboscis structure varied spinule size, SEM. (F) Details of clasper (arrow) and contiguous area, SEM. (G) Girdle segments, LM. (H) Girdle segments, SEM. Scale bars represent: A & B, 50 μm; C, 20 μm; D, & H, 5 μm; E, 0.5 μm; F, 1 μm; G, 10 μm.
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[Table 4.] Morphological characteristics of the Dactylisolen and Guinardia species examined in this study
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[Fig. 2.] Proboscia indica. (A) A complete cell, light microscopy (LM). (B) Apical part of valve, clasper (arrow) LM. (C) Apical part of the valve, clasper (arrow), scanning electron microcopy (SEM). (D) Details of Fig. 9, proboscis structure; longitudinal slit-like pore below the tip (arrow), SEM. (E) Details of the proboscis structure, varied spinule size, SEM. (F) Girdle segments, LM. Scale bars represent: A & B, 50 μm; C & F, 10 μm; D, 5 μm; E, 1 μm.
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[Fig. 3.] Neocalyptrella robusta. (A) A complete cell, light microscopy (LM). (B) Apical part of valve, external tube at the valve apex (arrow), LM. (C) Apical part of valve, valve with part of the cingulum, LM. (D) Apical part of valve, valve with part of the cingulum, scanning electron microscopy (SEM). (E) Striation at valve apex, SEM. (F) Valve apex showing calyptra structure and external tube, SEM. (G) Detail of cingulum; cingulum ends in an obtuse straight line, SEM. (H) Details of Fig. 3E loculate areolae, SEM. Scale bars represent: A, 100 μm; B & C, 20 μm; D, 50 μm; E & G, 10 μm; F, 0.5 μm; H, 2 μm.
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[Fig. 4.] Pseudosolenia calcar-avis. (A) A complete cell light microscopy (LM). (B) Complete cells, scanning electron microcopy (SEM). (C) Apical part of valve, internal structure of external process (arrow), LM. (D) Apical part of valve, claw or screw shaped external process (arrow), SEM. (E) Details of girdle segments, regularly straight striation, SEM. (F) Girdle segments, LM. (G) Apical part of valve, sigmoid contiguous area, SEM. (H) Screw shaped external process, SEM. Scale bars represent: A & B, 50 μm; C-E & H, 10 μm; F & G, 5 μm.
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[Fig. 5.] Guinardia delicatula. (A) Chain formed four cells, light microscopy (LM). (B) External process in valve marginal part (arrow), LM. (C-E) Guinardia flaccid. (C) A complete cells, LM. (D) Detail of girdle segments, LM. (E) Apical part of valve (arrow), LM. (F-H) Guinardia striata. (F) Chain formed two cells, LM. (G) External part of process, LM. (H) Girdle bands (arrow), LM. Scale bars represent: A-E, G & H, 10 μm; F, 20 μm.
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[Fig. 6.] Dactyliosolen fragilissimus. (A) Chain formed two cells light microscopy (LM). (B) Detail of external process in valve apex (arrow), LM. (C) Chain formed two cells, LM. (D) Detail of external process in valve apex (arrow), LM. (E-G) Dactyliosolen phuketensis. (E) Chain formed two cells, LM. (F) Apical part of valve, external process in valve marginal, LM. (G) Detailed girdle bands, half band, LM. Scale bars represent: A-D, F & G, 10 μm; E, 50 μm.