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Eleocharis ×myogiensis (Cyperaceae): A New Hybrid from Myoginohana Marsh, Lake Kasumigaura, Japan

Katsuhiro Yashiro* and Yasuhiko Endo

Graduate School of Science, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki, 310-8512 JAPAN*Corresponding author: yashirokatsuhiro@ybb.ne.jp

(Accepted on January 5, 2017)

A new plant hybrid was identified in Myoginohana Marsh, Lake Kasumigaura, Ibaraki Prefecture, Japan, and named Eleocharis ×myogiensis Yashiro (Cyperaceae). Its putative parents are E. petasata (Maxim.) Zinserl. and E. tsurumachii Ohwi. The hybrid has the floral and culm features intermediate between the putative parents, and a lower pollen stainability than that of the parents.

Key words: Cyperaceae, Eleocharis ×myogiensis, Eleocharis petasata, Eleocharis tsurumachii, Japan, Lake Kasumigaura, Myoginohana Marsh.

J. Jpn. Bot. 92(3): 157–164 (2017)

Myoginohana Marsh, in Inashiki-shi, Ibaraki Prefecture, occupies an area of approximately 52 ha located on the southwestern shores of Lake Kasumigaura (Nishiura)—the second largest lake in Japan. A total of 19 endangered plant species have been observed in the marsh, including Eleocharis tsurumachii Ohwi (Nozoe et al. 2010, Fujii 2015).

In our preliminary study, one of us (Yashiro) found four distinct morphotypes of Eleocharis in Myoginohana Marsh. Three of them were E. petasata (Maxim.) Zinserl., E. tetraquetra Nees, and E. tsurumachii Ohwi, whereas the fourth morphotype was morphologically intermediate between E. petasata and E. tsurumachii.

In the present study, we aimed to clarify whether the fourth morphotype was a hybrid between Eleocharis petasata and E. tsurumachii.

Materials and MethodsWe examined 17 individuals of Eleocharis

from Myoginohana Marsh, and the voucher specimens were deposited at the Ibaraki Nature

Museum (INM), Bando, Ibaraki Prefecture, Japan (Table 1). The length of spikes, scales, achenes, and hypogynous bristles, as well as the width of culms were measured from dried herbarium specimens using a Peak scale loupe 7× (Tohkai Sangyo, Bunkyo-ku, Tokyo, Japan) (Table 1). The lengths of spinules on the bristles were measured using an ocular micrometer under a transverse light microscope. For the measurements, more than five organs from one individual were examined, e.g., the length of spikes is an average of more than five spikes of one individual.

The culms of dried herbarium specimens were rehydrated by soaking in 5% aqueous KOH for 5 h (Lu et al. 2004, Both et al. 2009), washed with water, and then deposited in 70% aqueous ethanol. The rehydrated culms were manually sectioned into approximately 0.2 mm thick slices, using a razor blade. These sections were stained with aqueous safranin and observed under a transverse light microscope to count the number of vascular bundles and ridges at the

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Noguchi T. 1986. A study on Cyperaceae at Northern part of Kanto District in Japan (1) – on Eleocharis tsurumachii Ohwi. Ibaraki-Shokubutsu-Kenkyu 1: 83–85 (in Japanese).

Nozoe K., Nishiro J., Hotes S. and Washitani I. 2010. Importance of Ischaemum aristatum var. glaucum as an indicator of plant species richness in Myoginohana

Marsh, Lake Kasumigaura, Japan. Jpn. J. Conserv. Ecol. 15: 281–290 (in Japanese with English abstract).

Ohwi J. 1933. Symbolae ad Floram Asiae Orientalis 7. Acta Phytotax. Geobot. 2: 25–36.

Ohwi J. 1937. Corrigenda graviora ad “Symbolae ad Floram Asiae Orientalis”, “Plantae Novae Japonicae”, etc. Acta Phytotax. Geobot. 6: 151.

Yano O., Katsuyama T., Tsubota H. and Hoshino T. 2004. Molecular phylogeny of Japanese Eleocharis (Cyperaceae) based on ITS sequence data, and chromosomal evolution. J. Plant Res. 117: 409–419.

谷城勝弘，遠藤泰彦：霞ヶ浦妙岐の鼻産ハリイ属（カヤツリグサ科）の新雑種ミョウギノハリイ　茨城県霞ヶ浦（西浦）の湖岸である妙岐の鼻において，同地固有の絶滅危惧種カドハリイ Eleocharis tsurumachii Ohwiとユーラシア大陸東部に広く分布するミツカドシカクイ E. petasata (Maxim.) Zinserl.の推定雑種を発見し，産地に因んでミョウギノハリイと命名し，E. ×myogiensis Yashiroという学名を与えた．　カドハリイは刺針状花被片に，先端が漸尖形となる比

較的短い刺毛をつけることで近縁な他種から識別できる．一方，ミツカドシカクイは刺針状花被片に，先端が鈍形の長毛をつけることで特徴づけられる．これに対し，ミョウギノハリイは先端の尖った比較的長い毛をつけるという特徴を示し，前述の 2種の特徴をモザイク状に持っている．また，その花粉の染色性が低下する．

（茨城大学大学院理工学研究科）