Geranium biuncinatum ( Geraniaceae ) : un nuevo registro para la flora de Irán

Geranium biuncinatum Kokwaro was collected during a fieldwork around (Khuzestan province, Shoshtar to Masjed Soleyman) in South West of Iran. It is added as a new record for the flora of Iran. Micromorphological features of mericarps and seeds are investigated by Scanning Electron Microscopy. Differences between Geranium biuncinatum and its relatives are discussed. Its diagnostic characters, geographical distribution map and detailed pictures are given.


Introduction
The genus Geranium L. is a member of Geraniaceae family with about 325 species which are distributed through most parts of the world except lowland tropical regions (Aedo, 2017).Different number of species from 23 to 25 is recorded for the flora of Iran (Schönbeck-Temesy, 1970;Janighorban, 2005;Esfandani-Bozchaloyi et al., 2017 a, b, c, d).Yeo (1984) classified the genus Geranium into three subgenera: subg.Geranium, subg.Erodioidea (Picard) Yeo and subg.Robertium (Picard) Rouy.The subgenus Robertium is recognized by the carpel projection method for fruit discharge.It has been divided into eight sections.One of these sections is Geranium sect.Trilopha Yeo, which consists of seven species: Geranium biuncinatum Kokwaro, G. favosum Hochst., G. mascatense Boiss., G. ocellatum Cambess., G. trilophum Boiss., G. yemense Deflers.and G. brevipes Hutch.& Dalziel.Two species of this section were previously recorded for Iran: G. mascatense and G. trilophum (Schönbeck-Temesy, 1970).Laundon (1961) and Kokwaro (1971) had completely studied the Geranium sect.Trilopha in the Northeast tropical Africa.Aedo et al. (2016) also studied this section in their recent revision and monograph.In the present paper we are adding G. biuncinatum for the Flora of Iran.With this new record the total number of Geranium species known from Iran rises to 23.This study provides the macro and micro-morphological characters used for the species delimitation in Geranium sect.Trilopha from Iran.

Material and Methods
During field investigation in Khuzestan province, south west Iran, an interesting Geranium specimen was collected in May 1992 (Figure 1).This specimen was identified as Geranium biuncinatum.Different references were used for the correct identification of the species (Davis, 1967;Schönbeck-Temesy, 1970;Zohary, 1972;Janighorban, 2005;Aedo et al., 2016).The positive identification of the specimen was done in the herbarium of Tehran University Herbarium (TUH) (Figure 2) by a digital stereomicroscope Dino-Lite Pro (AM413T Model).For detailed micromorphological study the scanning electron microscope (SEM, JSM-6380A, JEOL) was used.Dry seeds and pollen grains were directly mounted on metallic stub using double adhesive tape and coated with gold for a period of 6 minutes in sputtering chamber (BAL-TEC, SCDOOS) and observed under SEM.The terminology used is in accordance with previously published studies of Punt et al. (1994) and Hesse et al. (2009).Differences between this newly recorded species and its relatives are discussed.In addition, locality and the distribution map are given.All the species of Geranium section Trilopha are annual herbs, erect or ascending, pubescent with short and long hairs in form of glandular and eglandular hairs (Figure 3G-I).Leaves are usually opposite.Most species have palmatifid leaves (with the divisions reaching about the middle), polygonal in outline and with five segments (Figure 3E).The five sepals form a quincuncial calyx.The two inner sepals are usually smaller and less pubescent than the others.The external surface of each sepal is smooth (Figure 3F).The petals are erect-patent, with entire apex and gradually tapering towards the base, that was, without a distinct claw.Petal color is usually purple with a dark basal spot (Figure 3D).The petals of all species are glabrous on both surfaces and ciliate on the basal margin with short eglandular hairs.

Geranium biuncinatum
To provide better distinction between Geranium biuncinatum, G. trilophum and G. mascatense seed and fruit micromorphology were considered.Mericarps of G. biuncinatum have toothed wings continuing in a pair of recurved horns which is a typical feature in the genus (Figure 3A,J-L).Whereas mericarps of G. trilophum have two longitudinal toothed wings bent dorsally to form a trough-like structure with an evident ridge in the middle, protruding from the trough-like structure (Figure 3B,O-P).The main difference between G. trilophum and G. biuncinatum is the presence of horns on mericarps of G. biuncinatum (Figure 3A).Sepals continued the growth and cover the mericarp in the latter (Figure 3F).Geranium mascatense is recognized by its distinctive mericarps with strongly prominent ribs and consequently, deep furrows (Figure 3C,M-N).By studying seed and fruit ornamentations it was found that these features are of diagnostic importance in section Trilopha.
Distribution.Geranium biuncinatum is found in Eritrea, Oman, Saudi Arabia, Somalia, Sudan and Yemen (Aedo et al., 2016), where it occurs on mountain slopes, from 200 to 2,300 m asl.The present location (Figure 1) is about 1,200 km far from the nearest location, according to Aedo et al. (2016).
Habitat.Geranium biuncinatum occurs on dry and stony soils at 150 m asl.It grows together with G. trilophum.Flowering time: May.

Discussion
Previous studies showed that morphometric studies are capable of species separation in the genus Geranium of Iran.(Esfandani-Bozchaloyi & Sheidai 2018;Esfandani-Bozchaloyi & Zaman 2018;Esfandani-Bozchaloyi et al. 2018a, b, c, d).Aedo et al. (2016) mentioned that there are two common features in all species of sect.Trilopha: a) "Erodiumtype" pollen grains with striate exine ornamentation and b) fruit with twisted rostrum.Our findings are in concordance with these observations.The highest diversity of the group is located in Iran, the Arabian Peninsula and adjacent regions of northeast Africa (Aedo et al., 2016).According to the latter authors there are some similarities between three species of this section.The identification key for species separation in Geranium sect.Trilopha provided by Aedo et al. (2016) distinguishes different species based on mericarp shape and petal color.Our observations are in concordance with Aedo et al. (2016).
Geranium trilophum is found in the Northern parts of the Persian Gulf; it was previously reported from Saudi Arabia by Alfarhan & Thomas (2001).The presence of G. biuncinatum besides two other species of Northern Africa is very interesting due to the penetration of tropical elements to Southern parts of Iran.