Bull. Natn. Sci. Mus., Tokyo, Ser. B, 30(4), pp. 151–154, December 22, 2004

Type Examination of Synedra delicatissima W.Sm. andIts Occurrence in Japan
Akihiro Tuji1 and Akiko Houki2
1

Department of Botany, The National Science Museum, Tokyo,
Amakubo 4–1–1, Tsukuba, 305–0005, Japan
E-mail: tuji@kahaku.go.jp
2
Faculty of Science, Nara Women’s University, Nara, 630–8506, Japan

Abstract A holotype specimen of Synedra delicatissima W.Sm. housed in the Dr. Henri vanHeurck Museum, Antwerp (AWH) was examined using scanning electron microscopes (SEMs)
and a light microscope (LM). Our observations are consistent with the original descriptions given
by Smith (1853) and Patrick & Reimer (1966). Japanese specimens from Lake Kizaki (NaganoPrefecture) and a pond in Tsukuba were belonging to this taxon.
Key words : Synedra delicatissima, holotype, Lake Kizaki.

Introduction
Two morphological types of Synedra delicatissima W.Sm. have been discussed by Patrick &Reimer (1966) and Krammer & Lange-Bertalot(1991). Patrick & Reimer (1966) present an original drawing of their proposed lectotype, basedon an isotype slide (BM22475) housed in the
Natural History Museum, London (BM). Krammer & Lange-Bertalot (1991) examined an isotype specimen and present a photograph of thistaxon. Since this photograph is quite different
from the drawing presented by Patrick & Reimer(1966), there has been a certain amount of confusion on the taxonomy of Synedra delicatissima
W.Sm.
Materials and Methods
The following materials were examined in thepresent study.
1. A raw material numbered Pg74 #1 in the W.
Smith collection sampled from Lough Neagh by
Dr. Dickie in 1850 and housed in the Dr. Henrivan Heurck Museum, Antwerp (AWH) (holotype),
2. A lectotype slide (BM22475) housed inBM,
3. A raw material sampled from Lake Kizaki(Nagano Prefecture) by A. Houki on April 5,2000 (TNS-AL-54215) housed in TNS (Department of Botany, National Science Museum,Tokyo), and
4. A raw specimen sampled from a pond in
Cyuo-Koen, Tsukuba by M. Watanabe on July11, 2004 (TNS-AL-55500 in TNS).
Results and Discussion
Two Synedra taxa were observed by lightmicroscopy (LM) on the lectotype slide(BM22475), the first of which is 30–60 m m longand shows 14–17 striae per 10 m m (Figs 1–2).
This taxon was dominant in the specimen, and isconsistent with the description and photographprovided by Krammer & Lange-Bertalot (1991).
The second taxon observed on the lectotype slide
has long frustules (150–250 m m) and a coarse
density of striae (10–11 striae per 10 m m) (Figs3–7). This species, though not dominant, is nevertheless common on the slide and is consistent
with the description and drawings presented byPatrick & Reimer (1986).
Smith (1853) was the first to describe S. deli-152Akihiro Tuji and Akiko Houki

catissima, and includes a description of the density of the striae (striae 28 in .001: about 11 striae per 10 m m) and length (.0048 to .0092: about
120–230 m m). This description and the figures
presented by Smith (1853) are more consistent
with the description and a figure in Patrick &Reimer (1986) than with those in Krammer &Lange-Bertalot (1991).
These two Synedra taxa were also observed byscanning electron microscopy (SEM) in the holotype specimen (Figs 8–15). S. delicatissima has
two large rimoportulae, one at each end of thefrustule (Figs 12–13, 15). A closed band with
punctum is also seen in Fig. 14. Another taxon,S. delicatissima sensu Krammer & LangeBertalot (1991), shows one rimoportula per frustule and should belong to the genus Fragilaria(Figs 8–11).
The specimens from Lake Kizaki (Figs 16–21)
and from a pond in Tsukuba were identified as S.
delicatissima. S. delicatissima is expected toexist in many Japanese lakes and ponds (Tanaka2002).

Figs. 1–7. Specimens from a lectotype slide ofSynedra delicatissima. BM22475. Bar
10 m m. 1–2. Synedra sp. (Synedra delicatissima sensu Krammer & Lange-Bertalot (1991)).
3–7. Synedra delicatissima W.Sm.

Synedra delicatissima W.Sm., Synops. Brit.
Diat. 72. pl. XII. f. 94. 1853.
(Figs 12–21)
Holotype: Pg74 #1 in the W. Smith collectionin AWH.
(Figs 12–15)
Type locality: North Ireland, Lough Neagh,Antrim.
Lectotype: BM22475 in BM designated byPatrick & Reimer (1986). (Plate 5, Fig. 2 inPatrick & Reimer 1986; Figs 3–7).
Synonym: Fragilaria delicatissima (W.Sm.)
Lange-Bert., Nov. Hedw. 33: 746. 1980.
non: Fragilaria delicatissima (W.Sm.) LangeBert. sensu Krammer & Lange-Bertalot, Bacill.
2/3. pl. 115. f. 13. 1991.
Hab.: Lake Kizaki, Nagano Prefecture (TNSAL-54215), a pond in Cyuo-Koen, Tsukuba,Ibaragi (TNS-AL-55500).
Acknowledgements
The authors would like to thank Dr. Guido Van
Steenbergen (Dr. Henri van Heurck Museum,Synedra delicatissima

153

Figs. 8–15. Specimens from a holotype raw material of Synedra delicatissima. Pg74#1 in the W.Smith collection. 8–11. Synedra sp. (Synedra delicatissima sensu Krammer & Lange-Bertalot (1991)). 8. Bar=10 m m. 9,
11. Bar0.1 m m. 10. Bar1 m m. 12–15. Synedra delicatissima W.Sm. Bar1 m m.

Antwerp) for his assistance in his museum andfor providing raw material from the W. Smithcollection. We would also like to thank to Dr.
David Williams (Natural History Museum, London) for his assistance in his museum.

References
Krammer, K. & Lange-Bertalot, H. 1991. Süßwasserflora
von Mitteleuropa. Bacillariophyceae. 3. Teil: Centrales,Fragilariaceae, Eunotiaceae, 2/3, 576pp. VEB Gustav
Fischer Verlag. Jena.
Patrick, R. M. & Reimer, C. W. 1986. The Diatoms of the154

Akihiro Tuji and Akiko HoukiFigs. 16–21. Synedra delicatissima W.Sm. A specimen from Lake Kizaki (Nagano Prefecture). TNS-AL-54215.
Bar1 m m.

United States Exclusive of Alaska and Hawaii. Monographs of the Academy of Natural Sciences of Philadelphia, 1, 688 pp., 64 pls.
Smith, W. 1853. A synopsis of the British diatomaceae.
89pp  31pls. John Van Voorst, London.

Tanaka, M. 2002. Illustrations of the Japanese Freshwater
Plankton. 584pp. The University of Nagoya Press,Nagoya (in Japanese).