Species Differentiation Of Cheniella In Leguminosae

The genus Cheniella R.Clark & Mackinder(Leguminosae: Cercidoideae)comprises 10 species and three subspecies,of which the species diversity center is in southern China,the full distribution extending westward to India and southeastward through Indochina into Malesia.Eight species and two subspecies of Cheniella are distributed in China(five species and two subspecies are endemic to China),mainly in southern and southwestern China.The study of morphological,geographical distribution and pollination biology of Cheniella will not only reveal the species differentiation pattern of the genus,but also provide a good example for explaining the diversity and the origin of species in southern and southwestern China,and also provide a reference for biodiversity conservation in China.In this study,eight domestic species of Cheniella(includes two subspecies)were studied in detail on the plant morphology,geographical distribution and pollination biology.The main results and conclusions are as follows:1.Morphological study1).According to different morphological characteristics,the degree of leaf apex,the length of hypanthium,the height of filament with matrue anthers,the color of petals,bending degree of the fruit and the fruit will crack,these characteristics can easily distinguish Cheniella from others;2).We found three suspected new species which is not described by predecessors;3)There are significant differences between C.sp 4 and C.corymbose,maybe it should be independent a new species.2.Study on geographical differentiationCheniella is distributed in all provinces which in south of Shaanxi Province and east of Tibet Province(except Taiwan Province).C.tenuiflora is distributed in all areas of Cheniella except Hainan Province,and C.sp 4 is only found in Hainan Province.The west of Guangxi Zhuang Autonomous Region has the highest species diversity of Cheniella,which contains 7 species,1 subspecies and2 suspected new species.We speculate that the western part of Guangxi Zhuang Autonomous Region is the center of origin and differentiation of Cheniella.Geographical isolation was not significant among species but subspecies level,for example: C.quinnanensis subsp.quinnanensis and C.quinnanensis subsp.villosa distributed in different areas.Karst area in the west of Guangxi Zhuang Autonomous Region has the highest species diversity of Cheniella,including 7 species,1 subspecies and 3 suspected new species.This area is the differentiation center of Cheniella.Among the 8domestic species of Cheniella,C.tenuiflora is the most widely distributed,and overlaps with all other species;The role of geographical isolation in species differentiation of Cheniella is mainly reflected in some closely related species or subspecies units.For example,the distribution areas of C.quinnanensis subsp.quinnanensis(distributed in Guangxi,Guizhou and Yunnan)and C.quinnanensis subsp villosa(only found in Yangjiang,Guangdong)are far apart.3.Study on Pollination biology:Cheniella rely on outcrossing to breed their offspring,but also retain the possibility of selfing.Artificial hybridization between different species in the genus can bear fruit normally,it is speculated that the reproductive isolation among Cheniella is mainly before zygote.The color of flower,time of flowering,florescence,nectar amount,degree of nectar sugar and hypanthium length together lead to the difference of pollinators.The details are as follows.(1)The color of flower: According to the color of flower,Cheniella can be divided into four categories: white,pink,green and yellowish green;(2)Florescence: Usually from March to November.Overall,the flowering periods overlap seriously.But the distribution of C.corymbosa(March to May)and C.didyma(July to October)overlap in Enping,Guangdong,their flowering periods are staggered;(3)Time of flowering: According to the time of flowering,Cheniella can be divided into two types: daytime flowering and evening flowering;(4)Amount of nectar can be divided into three categories,(1)>5?L,(2)5?L-3?L,(3)<2.5?L;Degree of nectar sugar can be divided into two categories,(1)>45%,(2)<36%;(6)Hypanthium length can be divided into three categories(1)>28 mm,(2)17 mm-25 mm,(3)<13 mm.The pollinators of Cheniella included: Nectariniidae,Pieridae,Sphingidae,Papilionidae,Apidae,Nymphalidae.Analysis of pollinator importance index: Xylocopa,Macroglossum and Papilio are the most important pollinators of C.corymbose;Bombus flavescens and Xylocopa are the most important pollinators of C.quinnanensis;Pieris canidia and Delias pasithoe curasena are the most important pollinators of C.touranensis;Papilio memnon is the most important pollinators of C.ovatifolia;Psithyrus,Papilio and Macroglossum are the most important pollinators of C.didyma;Macroglossum and Sataspes tagalica Boisduval are the most important pollinators of C.quinnanensis subsp villosa;Macroglossum is the most important pollinators of C.tenuiflora(Menghai);Psithyrus and Amegilla are the most important pollinators of Suspected new species 1;Xylocopa is the most important pollinators of Suspected new species 2;Aethopyga christinae and Macroglossum are the most important pollinators of C.sp 3;Macroglossum,Hippotion rosetta and Nectarinia asiatica are the most important pollinators of C.sp 4.In conclusion,the domestic genus Cheniella may contain 12 species and 2subspecies.Interspecific morphological differentiation mainly includes leaf morphology and morphological differentiation of breeding organs;Geographical differentiation occurred in some interspecific and subspecific levels;Reproductive isolation may be mainly caused by geographical isolation and pollinator differentiation caused by diversification of flowering period,flower color,flowering time,nectar amount,nectar sugar degree and hypanthium length.