A taxonomic revision of Germainia ( Andropogoneae : Poaceae ) in Thailand

A taxonomic revision of the genus Germainia (Andropogoneae, Poaceae) in Thailand is presented based on herbarium and field studies, including evidence from morphology, habitats and geographical distribution. Six of the nine recognized Germainia species are found in Thailand. We include a key to the taxa that are currently known from Thailand or may be expected, lists of species synonymies, species descriptions and lists of representative specimens.


INTRODUCTION
Germainia Balansa & Poitr. is a small genus in the tribe Andro pogoneae (Poaceae) comprising nine species and distributed in E India (Assam), S Myanmar (Tenasserim), Indo-China (Cambodia, Laos, Thailand, S Vietnam), S China (Guangdong (Canton), Yunnan), Indonesia (Aru Isl., Indonesian Papua), Papua New Guinea (Central, Sandaun (W Sepik), Western Prov.), and Australia (Northern Territory, N Queensland) (Chai-Anan 1972, Chen & Phillips 2006, Chen et al. 2007). Germainia was treated as a member of subtribe Germainiinae Clayton (represented by Apocopis Nees, Germainia and Trachypogon Nees) by Clayton (1972) based on morphological and anatomical data and specifically on the shared reduction in the sessile spikelet. Recognition of this subtribe was supported by Teerawatananon et al. (2011) using molecular DNA sequence data. However, the relationships of species within Germainia are still very much unknown.
Currently Germainia includes three genera: Germainia s.str., Chumsriella Bor and Sclerandrium Stapf & C.E.Hubb., which were reduced to Germainia by Chai-Anan (1972). She proposed a new circumscription of the genus based on the presence of basal pairs of homogamous involucral spikelets surrounding the central fertile awned spikelets and the presence of a tough rachis. She enumerated five species for Thailand.
During the preparation of a revision of Germainiinae for the Flora of Thailand Project, a number of new results were acquired. In addition, it was necessary to consider the typification of some names that had not been previously typified in order to fix their applications. Six taxa of Germainia are here revised.

MATERIALS AND METHODS
There were two main sources of specimens used in this study: specimens collected from fieldwork in Thailand and herbarium specimens, also from other areas, obtained from the following herbaria: AAU, ABD, BK, BKF, BM, C, E, GH, K, KKU, L, NY, SING, TCD, US and the Herbarium of Natural History Museum, National Science Museum, Technopolis, Pathum Thani, Thailand. Four field trips, totalling a period of five months were made in Thailand during 2005 and 2006. Several specimens per species were examined and measured if available. Spikelets from herbarium specimens were softened in water containing a small amount of detergent (c. 1 % of washing-up liquid), and measured using a stereomicroscope (Leica MZ-12) with a micrometer. Information on their distribution, ecology and habitat was taken from herbarium specimen data and field observations. Typification and synonymizations are based on literature (Chai-Anan 1972) and herbarium studies. Habitat & Ecology -Occurring in moist sandy soil, tropical grassland, tropical forest, and deciduous forest and also open and moist rocky plain areas. Found at elevations of 0 -1300 m.
Note - Kuntze (1903) regarded the name as confusable with Germa nea Lam. (1788, Lamiaceae), possibly named after J.J. de Saint Germain (c. 1784) (Backer 1936: 232 Notes -Chai-Anan (1972) divided this species into two groups of high (1000 -2000 m) and low (5-50 m) altitudes. Of the specimens examined in this study, only the specimens collected from the summit of Phu Kradueng (1000 -1300 m) are assignable to the high altitude plants, while the specimens collected from the other places (0-800 m) are assignable to the low altitude plants. We agree with Chai-Anan that the distinction between the two forms is insufficient for any taxonomic recognition as some characters are inconsistent, e.g. the shape of the apex of the lower glume of sessile spikelet is variable and ranges from obliquely bifid to muticous which can be found in both groups of plants, although most specimens from low altitude tend to have obliquely bifid apices, while the specimens from high altitude tend to have muticous ones. More material for further study is needed to clarify this situation.
Habitat & Ecology -On moist sandy soil in open areas, along stream banks, deciduous dipterocarp and mixed deciduous forests, and also on open and moist rocky plain areas, 500-800 m altitude. Specimens examined. Chantanamuck 224;Esser 98207;Murata et al. 50818, 50864;Norsangsri 568;Sunarnakoses 2016;Teerawatananon & Kritsanachandee 949;Teerawatananon & Sungkaew 886. Note -Chai-Anan (1972) mentioned that the width of the lower glume of the pedicelled spikelet was 1-1.4 mm. However, we examined the holotype and isotype from BKF, L, as well as fresh specimens in the field and found that their lower glumes are not wider than 0.6 mm.
Habitat & Ecology -On sloping sandstone with seeping water areas and grasslands on limestone areas, 150-900 m altitude.

CONCLUSION
Almost all members of this genus prefer moist and open sandy soil especially sandstone areas with seeping water. Only G. la nipes is restricted to limestone hills and can be found in the western part of Thailand.