Algae Volume 22(4): 253-259, 2007 우리나라황해의해산돌말류 Ditylum brightwellii (West) Grunow 의형태학적특징에의한두유형 이진환 * 윤석제 ( 상명대학교자연과학대학생명과학과 ) Classification into Two Types Based on the Morphological Characteristics of the Marine Diatom Ditylum brightwellii (West) Grunow in Yellow Sea, Korea Jin Hwan Lee* and Seok Jea Youn Division of Life Science, Sangmyung University, Seoul 110-743, Korea This study deals with the taxonomy of the marine diatom Ditylum brightwellii (West) Grunow: shape, size and ratio, marginal ridge, labiate process, areolation, and seasonal distribution are all considered. Ditylum brightwellii were divided into two type; prism- and cylinder-shaped. Comparisons between specimens from the Yellow Sea were made on, (1) shape- prism types are prismatic-shaped and/or regular square or right-angled tetragon, cylinder types are cylinder-shaped and/or long right-angled tetragon in the girdle view, respectively; (2) size and ratiodiameters of prism types are 82.1 ± 2 µm, while those of cylinder types are 21.2 ± 5 µm and ratio of pervalvar axis/diameter- prism types cells are 1.0-1.5, but cylinder types are 3.9-5.5; (3) marginal ridges- prism types have dotted, while those of the cylinder-type cells have piece, slotted or fimbriated on the marginal ridge; (4) labiate process- both prism- and cylinder-types are central part in valve face, but length of labiate processes of prism types are longer than those of cylinder types; (5) cell margin- the girdle margin show many shallow furrows in prism type and smooth in cylinder type; (6) areolation- both prism- and cylinder-types are a radial pattern in the valve center, but areolae of prism types are larger than those of cylinder types; (7) seasonal distribution- cylinder types are dominated in summer and prism types in the other seasons. Key Words: cylinder type, diatoms, Ditylum brightwellii, morphology, prism type 서론 Ditylum 속에속하는분류군은외부형태가가장유사한 Triceratium 속과비교하여, 전자는 (1) 투명하고규질화된각 (frustules), (2) 길고견고한중심돌기 (process), (3) 뚜렷한각을이루는곳에서아래로경사진부분으로경계를이루는편평한중심을하고있는뚜껑 (valve) 의독특한형태, (4) 세포의직경이큰점등을고려하여 1861년 L.W. Bailey 에의해Ditylum 속을발표하고이듬해출판하였다. 이와같은특징을가진분류군을 Bailey의부친은발표하지는않았지만 Grymaia 라는속명으로기록한것을아들에의해신 *Corresponding author (jhlee@smu.ac.kr) 속 Ditylum으로하였다. 초기에는속명도 Ditylum 또는 Ditylium으로혼용되었으나 (Van Heurck 1881), De Toni(1894) 가바로잡았다. Bailey(1862) 는 Ditylum trigonum과 D. inaequale 2종의기재문과그림과함께신속을설정하였다. 이보다앞서 West(1860) 는 Triceratium Brightwellii로서기재하고, 이를기준종으로하였다. 아마도 Bailey가 West(1860) 의논문을알지못했을것이라고가정하고있다 (Hendey 1937). 따라서 Grunow(1881) 에의해 Ditylum brightwellii로조합하였으며, Triceratium Brightwellii는이명 (synonym) 으로처리하였다. Van Landingham(1964) 은이속에 Ditylum Brightwellii, Ditylum cornutum, Ditylum grovei, Ditylum pernodi, Ditylum sol 등 5종을유효한학명으로출판하였으며, 최근 Hasle and Syvertsen(1997) 은 Ditylum brightwellii, Ditylum buchannii,
254 Algae Vol. 22(4), 2007 Table 1. Sampling date and locations of the marine diatom Ditylum brightwellii in the coastal waters of Yellow Sea, Korea Season Date Locations Latitude(N) Longitude(E) Summer Jul. 7, 2005 Pyung Taek Habor 36 58.1 126 45.0 Aug. 14, 2005 Karorim Bay 36 57.2 126 19.1 Aug. 29, 2005 Yeongheungdo Is. 37 16.1 126 20.1 Aug. 31, 2005 Incheon coast 37 26.0 126 31.0 Aug. 4, 2006 Yeongheungdo Is. 37 16.1 126 20.1 Aug. 11, 2006 Youngjongdo Is. 37 29.4 126 23.0 Aug. 22, 2006 Yeongheungdo Is. 37 16.1 126 20.1 Aug. 4, 2006 Incheon coast 37 26.0 126 31.0 Jun. 8, 2007 Palmido Is. 37 21.0 126 30.1 Jul. 27, 2007 Incheon coast 37 26.0 126 31.0 Autumn Oct. 5, 2005 Incheon coast 37 26.0 126 31.0 Oct. 13, 2005 Yeongheungdo Is. 37 16.1 126 20.1 Oct. 17, 2005 Incheon coast 37 26.0 126 31.0 Nov. 12, 2005 Yeongheungdo Is. 37 16.1 126 20.1 Nov. 25, 2005 Incheon coast 37 26.0 126 31.0 Oct. 22, 2007 Incheon coast 37 26.0 126 31.0 Winter Dec. 17, 2005 Incheon coast 37 26.0 126 31.0 Feb. 15, 2006 Yeongheungdo Is. 37 16.1 126 20.1 Feb. 3, 2007 Yeongheungdo Is. 37 16.1 126 20.1 Feb. 6, 2007 Incheon coast 37 26.0 126 31.0 Feb. 10, 2007 Yeongheungdo Is. 37 16.1 126 20.1 Spring Apr. 4, 2006 Youngjongdo Is. 37 29.4 126 20.1 May. 7, 2006 Yeongheungdo Is. 37 16.1 126 20.1 May. 11, 2006 Incheon coast 37 26.0 126 31.0 May. 27, 2006 Yeongheungdo Is. 37 16.1 126 20.1 Apr. 24, 2007 Yeongheungdo Is. 37 16.1 126 20.1 Apr. 10, 2007 Palmido Is. 36 58.1 126 45.0 May. 2, 2007 Yeongheungdo Is. 37 16.1 126 20.1 May. 18, 2007 Incheon coast 37 26.0 126 31.0 Ditylum pernodii, Ditylum sol 등 4종의목록을수록하였다. 우리나라에서는 Ditylum brightwellii, Ditylum sol 2종이기록되어있고 (Lee and Cho 1985; Lee 1995; 이등 1995), 두종간에는명확한분류학적차이가있으며, 검색표가잘정리되어동정에는어려움이없다 (Hustedt 1930; 久 1955; Hendey 1964; Hasle and Syvertsen 1997). 본연구의목적은우리나라황해의연안역에서 4계절출현빈도가높은 Ditylum brightwellii가외부형태에서크기뿐만아니라돌기의차이가현저함에도불구하고단일종으로취급하고있어, 유형 (type) 으로구분하고또한분자생물학적연구의전단계로분류학적형질을논의하고자연구하였다. 재료및방법시료의채집은황해연안의 6개지역에서 2005년 7월부터 2007년 10월까지 29회에걸쳐총 229정점에서실시하였다 (Table 1). 시료의채집은 1L 폴리에틸렌병과망목 20 µm 의 plankton net를사용하였으며, 현장에서 4% 중성 formalin 또는 2% glutaraldehyde로고정한후실험실로운반하였다. 실험실에서는침전법에의하여시료를 24시간이상침전시킨후상등액을 siphon으로버리고 150-200 ml로농축하였다. 정성분석을위하여농축된시료는적당량을 slide glass 위에놓고 100-1,000까지배율을조정하면서검정및동정하였다. 특히형태적특징을관찰하기위하여, 시료를슬라이드위에올려놓고광학현미경 (Axioskop 40, Zeiss) 100-1,000하에서검정하였다. 분류군의미세구조를파악하기위하여 glutaraldehyde로전고정시킨후 (0-4 C, 15-16 min.), 2% osmium tetraoxide로 4 C에서 3-4시간동안후고정하였다. 고정후 Et-OH series(50%, 60%, 70%, 80%, 90%: 각각 10 분씩 1회 ; 100%: 15분씩 2회 ) 로탈수, isoamylacetate series 로치환시켜 Critical Point Dryer(SPI, Dry-CPD) 로건조시킨후주사전자현미경 (JSM 5600 LV, Japan) 하에서두께축
Lee & Youn: Morphology of Ditylum brightwellii (West) Grunow 255 (pervalvar axis) 과직경을각각검경및계측하였다. 결과황해해역에서출현하는 Ditylum brightwellii를총29회의채집에서 619 개체를동정하여형태를관찰하였다. 이종의일반적인구조는다른돌말류와마찬가지로윗뚜껑 (epitheca), 아랫뚜껑 (hypotheca), 둘레띠 (girdle) 로이루어져있었다. Ditylum brightwellii의세포에는작고구형의엽록체가뭉쳐져있었다 (Figs 1-3 and 5-7). 세포를둘레면 (girdle) 에서보았을때프리즘형과원통형으로각각구분되었다 (Figs 1-4, and Figs 5-8). 둘레면보기 (girdle view) 에서프리즘형은세포의두께축 (pervalvar axis) 과직경 (diameter) 의길이가거의비슷하여정사각형에가까운직사각형이었고 (Figs 2, 3), 뚜껑면 (valve face) 의모양이삼각형이었다 (Figs 9, 10). 원통형은세포의두께축이매우길고, 직경이짧아가느다란형으로뚜껑면은원통상이었다 (Figs 5-8). 프리즘형이세포벽둘레면표면에골이이어져있는것처럼보이는반면 (Fig. 4), 원통형에서는표면이매끄럽고부드럽게보였다 (Fig. 8). 프리즘형의각투는뚜껑면가까이에서갑자기경사져세포전체보다작은삼각형으로가장자리융기 (marginal ridge) 를이루며 (Figs 9, 10), 원통형의각투도갑자기좁아들거나 (Fig. 13), 프리즘형과달리뚜껑면가까이에서세포전체의직경과같은원형의가장자리융기를이루는경우도있다 (Fig. 15). 프리즘형에서삼각형뚜껑면위에가장자리에는짧은가장자리융기가존재하며그위에가시는일정한간격으로늘어서있으나 (Figs 9-11), 원통형에서는원형의얕은접시가장자리모양이일정한간격에서홈이파여져있거나 (Figs 13, 14) 또는길고넓은헝겊모양으로기부에서합쳐져있다 (Fig. 15). 프리즘형과원통형모두둘레면보기에서긴입술돌기 (labiate process) 가뚜껑면중앙에서돌출되어져있으며, 형태는긴막대형이다 (Figs 9-12 and Figs 13-16). 이웃세포를연결하는입술돌기의평균길이는프리즘형과원통형에서각각 45.0±6 µm, 41.1±7 µm로 (Figs 1-8, 11 and 13), 프리즘형의것이더길었다. 프리즘형과원통형의뚜껑표면에서그물눈의배열은돌기를중심으로방사상으로배열되어있었다 (Figs 9, 10, 12, and Figs 13, 14, 16). 그물눈의크기는중앙에서바깥으로갈수록작아졌으며 (Figs 12, 16), 중앙부에서그물눈의수는프리즘형이 10 µm당 4개, 원통형이 5개로프리즘의그물눈이악간컸다 (Figs 12, 16). 각투 (valve mantle) 의그물눈은프리즘형에서 10 µm에 12개, 원통형에서 17개가있어역시프리즘형의그물눈이약간컸다. Table 2. Morphological characteristics of Ditylum brightwellii Characters Prism type Cylinder type Qualitative characters Shape of valve triangular shape rounded shape Pattern of Areola radial pattern radial pattern Labiate process one process in center one process in center Marginal spines dotted or fimbriated connected in one on valve face piece, slotted, or fimbriated Shape of girdle prismatic shape cylinder shape Girdle surface many shallow smooth furrows Quantitative characters Valve diameter 82.1 ± 2 21.2 ± 5 (µm) Areolae in 10 µm valve face 4 5 valve mantle 12 17 Pervalvar axis 96.0 ± 2 99.3 ± 3 (µm) Number of cells 52 19 (n) 두께축의평균길이는프리즘형과원통형이각각 96.0±2 µm, 99.3±3 µm이었고, 직경의평균길이는프리즘형과원통형이각각 82.1±2 µm, 21.2±5 µm이었다 (Table 2). 한편직경과두께축의길이를계절별로살펴보면, 직경은프리즘형이겨울철과봄철에각각 92.4±13.4 µm, 84.0±18.0 µm, 여름철과가을철과각각 59.4 ±21.0 µm, 69.7 ±10.1 µm로계절별차이가약간있었다 (Table 3). 반면에원통형은겨울철과봄철과각각 23.62 ± 3.7 µm, 15.2±3.1 µm, 여름철과가을철에각각 22.2±3.9 µm, 21.2±2.9 µm로매우가늘었다. 프리즘형의두께축은여름철에최저 83.2±28.6 µm에서가을철에최고 104.1 ± 17.7 µm이었으며, 원통형에서는겨울철과봄철에 91.1±30.6 µm, 77.5±11.3 µm이고, 여름철과가을철에는각각 101.5 ±28.8 µm, 115.8 ±35.8 µm로모든계절에직경대비매우길었다. 직경과두께축의비는계절별차이가약간있으나프리즘형에서는 1:1.0-1.5 였으나, 원통형에서는 1:3.9-5.5 로정도로확연하게차이를보이고있었다. Ditylum brightwellii의계절적출현개체수를보면가을철, 겨울철, 봄철에프리즘형이많이출현한반면, 원통형은여름철에우세한개체수를보였다. 즉, 프리즘형은수온이낮아질수록개체수가증가하였고 (y = -0.11x + 3.91, R 2 = 0.17, p < 0.001), 반면에원통형은수온이증가할수록그개체수가증가하였다 (y = 0.17x - 1.06, R 2 = 0.23, p < 0.001). 특히 20 이상의수온이높은시기에는원통형이 80.77% 가출현하였고, 20 C 이하에서는프리즘형이 91.42% 출현하여 20 C를
256 Algae Vol. 22(4), 2007 Plate 1. Whole shape of Ditylum brightwellii: Figs 1-3 and 5-7. LM photographs. Figs 4 and 8. SEM photographs. Figs 1-4. Girdle view of prism shaped, Figs 5-8. Girdle view of cylinder shaped. Scale bar = 25 µm.
Lee & Youn: Morphology of Ditylum brightwellii (West) Grunow 257 Plate 2. Detail structures of Ditylum brightwellii: Figs 9-12. Prism shaped Ditylum brightwellii. Figs 13-16. Cylinder shaped Ditylum brightwellii. Fig. 9. Valve view triangular in outline. Fig. 10. Central labiate process and fimbriated marginal ridges on the valve. Fig. 11. Long labiate process and valve mantle. Fig. 12. Areolation in radial rows on valve surface. Fig. 13. Valve view circular in outline. Fig. 14. Marginal ridge on the valve face. Fig. 15. Mantle view and fimbriated marginal ridges surrounding valve rim. Fig. 16. Areolation in radial rows on valve surface. Scale bar = 20 µm (Figs 9, 11), 10 µm (Fig. 15), 5 µm (Figs 10, 12, 15, 16), 2 µm (Fig. 13).
258 Algae Vol. 22(4), 2007 Table 3. Seasonal morphometric data of Ditylum brightwellii prism and cylinder shaped in the coastal waters of Yellow Sea, Korea Season Prism type(µm) Cylinder type(µm) Ratio (D:P)* Diameter Pervalvar axis Diameter Pervalvar axis Prism Cylinder n Summer 59.4 ± 21.0 083.2 ± 28.6 22.2 ± 3.9 101.5 ± 28.8 1 : 1.4 1 : 4.6 23 Autumn 69.7 ± 10.1 104.1 ± 17.7 21.2 ± 2.9 115.8 ± 35.8 1 : 1.5 1 : 5.5 17 Winter 92.4 ± 13.4 094.0 ± 15.6 23.6 ± 3.7 091.1 ± 30.6 1 : 1.0 1 : 3.9 30 Spring 84.0 ± 18.0 099.8 ± 25.6 15.2 ± 3.1 077.5 ± 11.3 1 : 1.2 1 : 5.1 12 * D: Diameter, P: Pervalvar axis Table 4. Seasonal comparison with cell density of Ditylum brightwellii prism and cylinder type in the coastal waters of Yellow Sea, Korea Season Cell density ( 10 3 cells L 1 ) Rate (%) No. of indiv.(n) Prism Type Cylinder Type PT CT PT CT Summer 0.89 1.56 36 64 107 185 Autumn 0.87 0.04 96 04 038 006 Winter 1.90 0.23 89 11 144 019 Spring 0.88 0.10 90 10 106 014 * PT: Prism Type, CT: Cylinder Type 기준으로한수온에따라형태의차이를보이고있었다. 그러나염분에의한유의적차이는나타나지않았다 ( 미발표자료 ). Ditylum brightwellii 계절적출현개체수를비율로보면프리즘형은가을철부터겨울철, 봄철에 89-96% 를점유하는데비하여, 여름철에 36% 에그쳤다 (Table 4). 반대로원통형은여름철에만 64% 로비교적높은점유율을보이나가을철부터이듬해봄철까지 4-11% 를보여계절적차이가뚜렷하였다. 고찰본연구에서관찰한 Ditylum brightwellii의엽록체는작고구형의모양이가운데또는한쪽으로치우쳐뭉쳐있었으며, 기존의연구에서도유사하였다 (Hendey 1937, 1964; Cupp 1943). Ditylum brightwellii 프리즘형의세포벽은표면에수직으로얕은골이매끄럽고부드럽게파여져있으며, 그물눈도역시선형의무늬를보인다. 반면에원통형에서는매끄럽고작은그물눈으로덮혀있었다. 세포의크기는두께축의평균길이가프리즘형과원통형이각각 96 ± 2 µm, 99 ± 3 µm이었고, 직경의평균길이는프리즘형과원통형이각각 82 ± 2 µm, 21 ± 5 µm이었다. 본종의크기를기존의문헌에서보면직경은 76-80 µm(skvortzow 1932), 60-180 µm(hendey 1937), 14-85 µm(cupp 1943), 25-100 µm( 久 1955; Takano 1979; Hasle and Syvertsen 1997), 28-46 µm (Hendey 1964) 이었고, 두께축은 80-130 µm(hendey 1937, 1964; Hasle and Syvertsen 1997), 80 µm( 久 1955) 였다. 본연구에서프리즘형의두께축 / 직경비율은 1.0-1.5 이고, 원통형은 3.9-5.5 로차이가뚜렷하였고, 두형태를구분하지않은 Hendey(1964) 는두께축이직경의 3-8배에이른다고하여큰변이가있음을보고하였다. 프리즘형과원통형의이웃세포와의연결하는입술돌기의평균길이는각각 45.0 ±6 µm, 41.1 ±7 µm이었으나, Hendey(1937, 1964) 의두연구에서각각 60-76 µm, 20-50 µm으로보고하여변이가심하였다. 이돌기의명칭은초기에는뿔 (horn) 로 (Hustedt 1930; Skvortzow 1932), 가시 (spine)(hendey 1937, 1964; Cupp 1943; 久 1955), 최근에는 Ditylum brightwellii의세포벽의형성과정과입술돌기의형성과세포분열에서입술돌기 (labiate process) 로명확히하였다 (Li and Volcani 1985; Pickett-Heaps et al. 1988; Hasle and Syvertsen 1997). 프리즘형에서삼각형의가장자리융기위에가시는일정한간격으로늘어서있으나, 원통형에서는원형위에얕은접시가장자리모양이일정한간격에서홈이파여져있거나또는길고넓은모양으로기부에서합쳐져있어특징이매우달랐다. 그러나, 과거의광학현미경사진또는그림자료에서는이들모양과비교할수는없었다. 프리즘형과원통형모두뚜껑면의다공그물눈은뚜껑면중앙에서바깥쪽으로방사상배열을하며, 이는 Li and Volcani(1985) 의연구에서도동일하였다. 즉, 다공그물눈의크기는중앙의입술돌기에가까이있는것이크며각투에가까워질수록크기는점점더작아졌다. 단공은뚜껑면중앙에
Lee & Youn: Morphology of Ditylum brightwellii (West) Grunow 259 있는입술돌기주변을불규칙하게에워싸고있으며, 원통형에서더잘발달하였다. 다공그물눈과단공의전자현미경적미세구조를 Saitow and Chihara(1982) 와 Li and Volcani (1985) 의연구에서도관찰되었다. Ditylum brightwellii의생태적특징은연안성으로온대해역에서주로출현하며 (Hustedt 1930; Skvortzow 1932; Cupp 1943; 久 1955; Hendey 1964), 일부아열대및열대해역에서도관찰한바있다 (Hendey 1937; Sournia 1968). 우리나라에서는사계절출현하고있으며 (Lee 1995), 늦여름부터초가을에높은출현빈도를보인다고하였다 ( 심 1994). Ditylum brightwellii의원통형은여름철에우세하였고, 나머지계절에서는프리즘형이우세하여수온과밀접한관련이있는것으로판단된다. 프리즘형은수온이낮아지는가을철부터봄철에이르기까지출현빈도의거의 90% 이상을차지하여이를뒷받침하고있다. 다만, Ditylum brightwellii의수온과관련된형태학적연구가이루어지지않아기존의연구결과와비교하기어려우나앞으로수온에따른극단적인형태차이를나타내는유형을배양을통하여확인하거나분자생물학적연구에의해규명해야할것이다. 사 사 본연구는 2007학년도상명대학교연구비지원에의하여수행되었습니다. 본연구를위하여시료의채집과자료정리를해준상명대학교해양연구실원들에게감사를표합니다. 참고문헌 심재형. 1994. 한국동식물도감. 제 34 권식물편 ( 해양식물플랑크톤 ). 교육부 487 pp. 이경, 최중기, 이진환. 1995. 한국산돌말류 ( 규조류 ) 의분류학적연구 II. 출현목록. 한국조류학회지 ( 보유호 ) 10: 13-89. 久, 1955. 硅. 閣. 京. pp. 330. Bailey L.W. 1862. Notes on new species of microscopical organisms, chiefly from the Para River, South America. Bost. Journ. Nat. Hist. 7: 329-352. Cupp E.E. 1943. Marine plankton diatoms of the west coast of North America. Bull. Scripps Inst. Oceanogr., Univ. Calif. 5: 1-238. De-Toni J.B. 1891-94. Sylloge Bacillariearum omnium hucusque cognitarum. In: Sylloge algarum. Patavi, II. Bacillarieae, Sec. 1-3, 1556 pp. Grunow A. 1881. Ueber die Arten der Gattung Grammatophora mit Bezug auf die Tafeln LIII und LIII B, in Van Heurck s Synopsis der belgischen Diatomeen. Beil. Bot. Centralbl. 7: 1-15. Hasle G.R. and Syvertsen E.E. 1997. Marine diatoms. In: Tomas C.R. (ed.), Identifying Marine Phytoplankton. Academic Press, California. pp. 5-386. Hendey N.I. 1937. The plankton diatoms of the Southern Sea. Discovery Rep. 16: 151-364. Hendey N.I. 1964. An introductory account of the smaller algae of British coastal waters 5: Bacillariophyceae (Diatoms). In: Ministry of Agriculture, Fisheries and Food (ed.), Fishery Investigations Series IV. HMSO, London. 317 pp. Hustedt F. 1930. Die Kieselalgen Deutchlands, Österreichs und der Schweiz usw. Rabenhorst, Kryptogamen-Flora, Bd. 7, Teil I. Leipzig. Lee J.H. 1995. Additional check-list of marine planktonic algae in the coastal waters of Korea. I. Bacillariophyceae. J. Natural Sci., Sangmyung Women s Univ. 2: 71-198. Lee J.H. and Cho C.H. 1985. Check-list of marine planktonic algae in the coastal waters of Korea I. Bacillariophyceae. Ocean Reserach 7: 9-47. Li C.W. and Volcani B.E. 1985. Studies on the biochemistry and fine structure of silica shell formation in diatoms VIII. Morphogenesis of the cell wall in a centric diatom, Ditylum brightwellii. Protoplasma 124: 10-29. Pickett-Heaps J.D., Wetherbee R. and Hill D.R.A. 1988. Cell division and morphogenesis of the labiate process in the centric diatom, Ditylum brightwellii. Protoplasma 143: 139-149. Saitow M. and Chihara M. 1982. Laboratory culture and morphology of a marine centric diatom Ditylum brightwellii (1). General morphology and vegetative cell division. Jap. J. Phycol. 30: 225-233. Skvortzow B.W. 1932. Diatoms from the bottom of the sea of Japan. Philippine J. Sci. 47: 265-280. Sournia A. 1968. Diatomées planctoniques du Canal de Mozambique et de l ile Maurice. Mémoire O.S.T.O.M. 31: 1-120. Takano H. 1979. New and rare diatoms from Japanese Marine waters-iii. Lithodesmium variabile sp. nov. Bull. Tokai Reg. Fish. Res. Lab. 55: 1-7. Van Heurc H. 1880-1885. Synopsis des diatom es de Belgique, pp. 235, 132 suppl. A, B, and C plates, Antwerp. Van Landingham S.L. 1964. Catalogue of the fossil and recent genera and species of diatoms and their synonyms. Part III. p. 1087-1756. West T. 1860. Remarks on some Diatomaceae, new or imperfectly described, and a new desmid. Trans. Micr. Soc. Lond. N.S. 6: 147-153. Received 15 October 2007 Received 17 November 2007