Bull. Natl. Mus. Nat. Sci., Ser. B, 35(1), pp. 11–16, March 22, 2009

The Transfer of Two Japanese Synedra Species (Bacillariophyceae)
to the Genus Ulnaria
Akihiro Tuji
Department of Botany, National Museum of Nature and Science, Amakubo 4–1–1, Tsukuba, 305–0005 Japan
E-mail: tuji@kahaku.go.jp

Abstract Two Japanese diatom species, Synedra japonica F. Meister and S. rostrata F. Meister,described by Friedrich Meister (1913) from Lake Suwa, are transferred to the genus Ulnaria. The
two species have diagnostic characters of the genus Ulnaria, including one rimportula at each apexof the valve and closed girdle bands.
Key words : diatom, new combination, nomenclature, Synedra japonica F. Meister, Synedra rostrata F. Meister, Ulnaria japonica (F. Meister) Tuji, Ulnaria rostrata (F. Meister) Tuji.

Introduction
Synedra japonica F. Meister and S. rostrata F.
Meister were described by Meister (1913) from
Lake Suwa. The type slides have been examinedby Tuji and Williams (2007), who designated lectotypes for these taxa. Morphological descriptions based on light microscopy are also done inTuji and Williams (2007).
The generic placement of Synedra ulna
Nitzsch and related species, including S. japonica and S. rostrata, which is discussed in thispaper, has been confused during the last twentyyears. Williams and Round (1986) separated thegenus Synedra Ehrenb. sensu lato into six genera
based on morphological characters. This reclassification is widely accepted by recent diatomists.
Williams (1986) mentioned the problem of thetype species of the genus Synedra noting “it will
be necessary to conserve the type of Synedra if
the most commonly associated species are to retain that name”. However, no proposal to conserve the type of Synedra has been submitted.
Compère (2001) notes that the taxon known as S.
ulna and related species do not belong to Synedra
if Synedra balthica Ehrenb. is recognized as thegeneritype. As a result, Compère (2001) formally
proposed the genus Ulnaria (Kützing) Compère,
based on Kützing’s previously unranked Synedra

Ulnaria Kützing (1844) and Frenguelli’s Synedra
subgenus Ulnaria (Kützing) Frenguelli (1929),
which are typified by S. ulna. Many monographs
such as Iconographia Diatomologica, Bibliotheca Diatomologica, etc.) are recognizing andusing Ulnaria. Furthermore, with the formal
recognition of Ulnaria at the genus level, it has
become increasingly difficult to revert back to thename Synedra through a proposal to conserve thetype.
Although Compère (2001) carefully worded
argument for recognizing Ulnaria at the genus
level and his transfer of five taxa was perfectly
valid, the lack of a summary description of thecharacters that are shared by Ulnaria species hasslowed the acceptance of Ulnaria. Furthermore,
there has not yet been a monographic treatmentof Ulnaria, and many taxa that clearly belong inthis genus await formal transfer. A summary of
the morphological characters that are shared
among Ulnaria species include: linear to lanceolate valves with uniseriate or biseriate striae composed of areolae occluded by simple vela, twoapical pore fields and rimoportulae (labiateprocess) per valve, one at each valve end, apicalpore fields of the ocellulimbus type, multiple
closed girdle bands, and two girdle-appressedplate-like plastids.
Because of the confusion of taxonomic posi-12Akihiro Tujitions of S. japonica and S. rostrata based on
characters resolved in the light microscope (Tujiand Williams, 2007), we examined the ultrastructure, especially the number and position ofrimoportulae per valve and band morphologies
using SEM, and discuss the synonymy andgeneric placement of these taxa.
Materials and Methods
Two collections of raw material housed in TNS(Department of Botany, National Museum ofNature and Science), were examined using an
SEM (JSM-6390 with LaB6 gun, JEOL, Japan).
The material for Synedra rostrata F. Meister,
TNS-AL-TW-12581 was collected from River
Tamagawa (R. Obonai), Akita Pref., Japan[39°41N, 140°43E] on 13/xi/1994 by Toshiharu
Watanabe. The electric conductivity at the timeof collection was 195 m S/cm, pH was 8.2, andwater temperature was 10.5 Celscius degrees.
This material was also used for Algae aquae dulcis Japonicae exsiccata: nos. 2 (Tuji, 2007).
The material for Synedra japonica F. Meister,TNS-AL-55265 was collected from Lake Yogo,
Shiga Pref., Japan [35°31.752N, 136°11.662E]
on 18/iv/2000 by Akihiro Tuji. The electric conductivity at the time of collection was 94 m S/cm,and pH was 8.1. This material is going to be distributed for the next issue of Algae aquae dulcis
Japonicae exsiccata.
Results and Discussion
Ulnaria rostrata (F. Meister) Tuji comb. nov.
Basionym: Synedra rostrata F. Meister, Arch.
Hydrobiol. 8: 312. pl. IV, f. 7. 1913.
Lectotype (designated in Tuji & Williams
2007): BRM “K2/57”!
Isotype: Slide no. 801 Tempère et Peragallo(2nd edition), BM69152!
Synonyms:
Synedra inaequalis H. Kobayasi in Kobayasi,
H., Idei, M., Kobori, S. & Tanaka, H. Diatom 3:
9–10. f. 2–13. 1987.
Ulnaria inaequalis (H. Kobayasi) M. Idei in

H. Kobayasi’s Atlas Jap. Diat. Electr. Microsc. 1:86. 2006.
Type locality: Lake Suwa, Nagano Pref.,Japan.
From SEM observations, two large rimoportulae exist, one at each end of the valves (Figs.
1–8). At least, three closed girdle bands were observed (Figs. 4–5). Small, rounded apical porefields surrounded externally by a slightly thickened siliceous rim are on each end of the valve.
SEM micrographs of this taxon were also presented by Kobayasi et al. (1987) and Kobayasi etal. (2006) as S. inaequalis. The variation observed for Synedra rostrata F. Meister is that ofSynedra inaequalis H. Kobayasi in Kobayasi etal. (1987), suggesting they are synonyms. Myobservation in this paper, that two large rimoportulae exist, one at each end of the valve, also
agrees these previous observations. A rimportulaat each valve apex was also observed using LM
in the designated lectotype in LM (Tuji andWilliams, 2007).
Because the characters of two rimportulae pervalve and closed girdle bands are those of thegenus Ulnaria (Compère, 2001), I hereby propose the transfer of Synedra rostrata to the genus
Ulnaria.

Ulnaria japonica (F. Meister) Tuji comb. nov.
Basionym: Synedra japonica F. Meister, Arch.
Hydrobiol. 8: 312. pl. IV, f. 5–6. 1913.
Lectotype (designated in Tuji & Williams
2007): BRM “K2/59” !
Isotype: Slide no 801, Tempère et Peragallo(2nd edition), BM69152!
Type locality: Lake Suwa, Nagano Pref.,Japan.
In SEM observations, two large rimoportulae
exist, one at each end of the valve (Figs. 11, 12,13 and 15). Three closed girdle bands are observed (Figs. 9–12). The central area is much
longer than broad (Fig. 14). A rimportula at eachvalve apex was also observed in LM in the designated lectotype (Tuji and Williams, 2007).
Because the characters, two rimportulae perSynedra japonica and S. rostrata

Figs. 1–5. Ulnaria rostrata (F. Meister) Tuji comb. nov., TNS-AL-TW-12581. 1–5. Outer view of a valve. 1–3.
same valve. 1. Whole valve, 2–5. A rimoportula is located at each apex. 4 and 5. At least, three closed girdlebands exist. 1. bar10 m m. 2 and 3 bar0.5 m m. 4 and 5. bar1 m m.

13

14Akihiro TujiFigs. 6–8. Inner view of a valve, all images of same valve. 6. whole valve. 7 and 8. A rimoportula and apicalpore field are found at each valve apex. 6. bar5 m m. 7 and 8. bar0.5 m m.

Synedra japonica and S. rostrata

Figs. 9–15. Ulnaria japonica (F. Meister) Tuji comb. nov. 9–12. TNS-AL-55265, three closed valves are exist.
11–15. A rimoportula and apical pore field are located in each valve apex. 9, 11 and 12. bar0.5 m m. 10, 13and 15. bar1 m m. 14. bar5 m m. 13–15. after Tuji and Williams (2007: p. 73).

15

16

Akihiro Tujivalve and closed girdlebands, are charactersshared among species in the genus Ulnaria(Compère, 2001), I hereby propose the transferof this taxon to the genus Ulnaria as U. japonica.
Acknowledgements
I express our thanks to Dr. Mark Edlund, Science Museum of Minnesota for the kind advice
and English check on this paper.
References
Compère, P. 2001. Ulnaria (Kützing) Compère, a newname for Fragilaria subgen. Alterasynedra LangeBertalot with comments on the typification of Synedra
Ehrenberg. In: Jahn, R., Kociolek, J. P., Witkowski, A.
and Compère, P. (eds.) Lange-Bertalot Festschrift,
Studies on diatoms dedicated to Prof. Dr. Dr.h.c. Horst
Lange-Bertalot on the occasion of his 65th birthday,
pp. 97–101. A.R.G. Gantner Verlag K.G.
Frenguelli, G. 1929. Diatomee fossili delle conche salinedel deserto cileno-boliviano. Bollettino della Societa
Geologica Italiana 47: 185–236.

Kobayasi, H., Idei, M., Kobori, S. and Tanaka, H. 1987.
Observations on the two rheophilic species of the genus
Synedra (Bacillariophyceae): S. inaequalis H. Kob. andS. lanceolata Kütz. Diatom 3: 9–16.
Kobayasi, H., Idei, M., Mayama, S., Nagumo, T. andOsada, K. 2006. H. Kobayasi’s Atlas of Japanese Diatoms based on electron microscopy. 531 pp. Uchida
Rokakuho Publishing Co. Ltd., Tokyo (In Japanese).
Kützing, F. T. 1844. Die Kieselschalien bacillarien oder
Diatomeen. W. Köhne, Nordhausen.
Meister, F. 1914. Beitrage zur Bacillariaceenflora Japan.
Archiv für Hydrobiologie und Planktonkunde 9:
226–232.
Tuji, A. 2007. Algae Aquae Dulcis Japonicae Exsiccatae.
Fasc. I. nos. 1–20. 29 pp. National Museum of Natureand Science, Tsukuba.
Tuji, A. and Williams, D. M. 2007. Type examination ofJapanese diatoms described by Friedrich Meister(1913) from Lake Suwa. Bulletin of the National Science Museum, Series B, 33: 69–79.
Williams, D. M. 1896. Comparative morphology of somespecies of Synedra Ehrenb. with a new definition of thegenus. Diatom Research 1: 131–152.
Williams, D. M. and Round, F. E. 1986. Revision of thegenus Synedra Ehrenb. Diatom Rsearch 1: 313–319.