Three new species of Impatiens (Balsaminaceae) from southern Western Ghats, Kerala

Abstract Three new species of Impatiens, Impatiensachudanandanii, I.danii, and I.shailajae, are described from Thiruvananthapuram and Idukki districts of Kerala state (SW-India). Impatiensachudanandanii is similar to I.courtallensis and I.herbicola; I.danii to I.goughii and I.shailajae is to I.minae and I.scapiflora. The newly described taxa are readily distinguished from their allied species by unique character combinations, viz. shape of lateral sepal, lower sepal, dorsal petal, seed and pollen morphology. Detailed descriptions along with illustrations and photographs are provided.


Introduction
Balsaminaceae A. Rich consists of about 1,000 species, mainly distributed in tropical Africa, Madagascar, southern India, and Sri Lanka (see e.g., Yuan et al. 2004). This family includes annual or perennial herbs (more or less succulent) or subshrubs. (Stevens 2012). It comprises the monotypic genus Hydrocera Blume ex Wight & Arn. and the genus Impatiens L. having variously united and characteristic petals with dehiscent fruits (Mabberley 2008;Bhaskar 2012). Impatiens is mainly distributed in the tropics and subtropics of the Old World, whereas few species occur in temperate regions of Eurasia and North America. Five diversity hotspots for Impatiens have been recognized, i.e. tropical Africa, Madagascar, southern India and Sri Lanka, the eastern Himalayas, and southeast Asia (Song et al. 2003;Yuan et al. 2004). During the past two decades, extensive contributions to the taxonomy of the genus Impatiens were made (Yu et al. 2015;Rahelivololona 2015a, b, c, 2016;Fischer et al. 2017). Yu et al. (2015) divided Impatiens into two subgenera Clavicarpa and Impatiens with 7 sections viz. Semeiocardium, Impatiens, Tuberosae, Racemosae, Uniflorae, Scorpioidae and Fasciculatae. The three new species described here belong to the subgenus Impatiens characterized by 5-carpellate (rarely 4) ovary, many ovules per locule; fusiform, linear, cylindrical or clavate capsule; pollen 4-aperturate (rarely 3-aperturate), oblong, circular, elliptic or quadrate.
Impatiens is represented by more than 210 taxa in India, mostly distributed through the Eastern Himalayas and the Western Ghats (see e.g., Bhaskar 2012). More than 106 species are endemic to the Western Ghats, of which 80% are endangered (Bhaskar 2012). Moreover, several endemic taxa have been recently reported from various parts of the Western Ghats (Hareesh et al. 2015;Chhabra et al. 2016;Vishnu et al. 2020).
The interiors of Kerala forest ranges are bestowed with rich biodiversity and many of which warrant keen exploration. During such field explorations, in a span of two years, we came across three interesting species of the genus Impatiens from Thiruvananthapuram and Idukki districts of Kerala. Critical analysis of the specimens revealed that these cannot be ascribed to any known species of Impatiens and hence described here as new.

Materials and methods
Extensive field surveys were conducted in Kerala during the period 2019-2021. Analysis of relevant literature (Hooker and Thomson 1860;Hooker 1875Hooker , 1904Hooker -1906Hooker , 1908aHooker , b, 1910Hooker , 1911Dessai and Janarthanam 2011;Bhaskar 2012;Hareesh et al. 2015;Ramasubbu et al. 2015Ramasubbu et al. , 2017Bhaskar and Sringeswara 2017;Mani et al. 2018) and careful examination of preserved specimens preserved at various herbariums (TBGT, KFRI, MH, USF, K, CALI, and CMPR) (acronyms according to Thiers (2021) [continuously updated]) were undertaken to complete the study. Furthermore, distribution map was created using QGIS Version 3.14. Diagnosis. Impatiens achudanandanii is similar to I. courtallensis Ramasubbu, from which it differs by the color of the flowers (whitish-creamy with yellow spot at throat in I. achudanandanii vs. milky-white in I. courtallensis), the shape of the fruit, the shape, number and hairiness of the seeds (ovoid, 2-3 seeded fruit and seed glabrous in I. achudanandanii vs. fusiform, 3-5 seeded and with minute hairs in I. courtallensis), the shape of the dorsal petal (ovoid-circular in I. achudanandanii vs. orbicular, recurved in I. courtallensis), the shape of the lateral united petals (basal lobe ovate-obovate, distal lobe round in I. achudanandanii vs. basal lobe oblong, distal lobe spherical in I. courtallensis), the shape of lower sepal (saccate and tip pointed in I. achudanandanii vs. boat shaped and tip outwardly curved in I. courtallensis) and the size and color of the pollen grains (10 × 16 µm whitish-yellow in I. achudanandanii vs. 16 × 18 µm squarish, milky-white in I. courtallensis).
Etymology. Impatiens achudanandanii is named in honor of Mr. V.S. Achudanandan, former Chief Minister of the state of Kerala for his ardent efforts in conservation of the pristine environment of Western Ghats, especially Mathikettan shola.
Phenology. August to November. Distribution and habitat. Impatiens achudanandanii is distributed in the highlands above 1200 m. So far, the specimen has been observed only in the type locality. The populations are scattered and under the threat of grazing and other anthropogenic pressures. The plants are found to grow associated with seasonal ditches near the shade of huge rocks. Species of Eriocaulon, Utricularia reticulata and Drosera indica were found to grow in the nearby vicinity of this species Conservation status. Impatiens achudanandanii is assessed as Critically Endangered (CE) according to the IUCN categories using the criterion d (IUCN 2019). There were only three to four populations (10-15 individuals per population) observed within 1 km. The habitat of the species was severely affected by stamping of wild elephants and land-slides.
Other notes. Impatiens achudanandanii belongs to the section Uniflorae under the subgenus Impatiens. characterized by ellipsoidal shape of seed and capsules that are short and conspicuously turgid at middle. The new species resembles I. courtallensis, a species reported from Courtallam hills of Tamil Nadu and also I. herbicola, a common high altitude species. The shape of dorsal petal, minute size of flower and the presence of spur distinguished the newly described species from its allied taxa. Impatiens achudanandanii is distinct from its other allied taxon I. herbicola with respect to spur (present in I. achudanandanii vs. absent in I. herbicola), color of the flower (whitish-creamy with yellow spot at throat in I. achudanandanii vs. bluish or yellowish in I. herbicola), size of the flower (2-3 mm in I. achudanandanii vs. 5-9 mm in I. herbicola), shape of the fruit (ovoid 2-6 seed in I. achudanandanii vs. gibbously ovoid with many seeded in I. herbicola), shape of lateral united petals (   in I. danii vs. ellipsoidal in I. goughii) and shape of seed (ellipsoidal with bands of hairs in I. danii vs. ovoid with short hairs in I. goughii).
Etymology. The specific epithet 'danii' is given in honor of Dr. Mathew Dan, Senior Scientist and Head, Plant Genetic Resource Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Thiruvananthapuram, Kerala, as a recognition of his immense contributions in the field of systematics and conservation of angiosperms in the Western Ghats.
Phenology. August to November Distribution and habitat. Impatiens danii is found to grow along the mud cliffs. Other taxa like I. herbicola, I. munnarensis and Selaginella ciliaris have been observed to grow along with this species.
Conservation status. Impatiens danii is known from a single location only (for a total of 50 individuals), and the AOO (Area of Occupancy) is 2 km 2 . On the basis of the IUCN Red List criteria (IUCN 2019) and the available data, we can apply the criteria B2 and C2ai and assess I. danii as Critically Endangered (CR).
Other notes. Impatiens danii belongs to the section Uniflorae, characterized by capsules that are short-fusiform, conspicuously turgid at middle, ca. 1 cm long, inflorescence a raceme with 2(-5) flowers and seed ellipsoid. Further the color of flower, blotches on throat, seed surface and shape of spur are distinct characters that delineate I. danii from other reported species.
Specimen examined. Impatiens danii India. Munnar, Idukki. 6 July 2020, M.G. Govind 987 (TBGT!). I. goughii India. Munnar, Idukki. 6 July 2020, M.G. Govind 988 (MH!). Diagnosis. Impatiens shailajae is similar to I. minae Ratheesh, Anil Kumar & Sivad. but differs with respect to the leaves (broadly ovate thin, rounded apex and green in I. shailajae vs. broadly ovate-orbicular, thick, fleshy, deep pink in I. minae), spur of the flower (straight and white in I. shailajae vs. slightly curved and pink in I. minae), lateral united petals (with white transparent papillae and small dorsal appendages in I. shailajae vs. red tipped white papillae and absence of dorsal appendages in I. minae) and seed (green with long bands of spiral hairs in I. shailajae vs. brown with short hairs in I. minae)
Etymology. Impatiens shailajae is eponymous to Mrs. K.K. Shailaja, former Health Minister of Kerala, honoring her efforts to tackle various epidemic and pandemic situations in the state of Kerala through scientific temper.
Phenology. August to November. Distribution and habitat. The species grows in the unexplored core forest area along steep slippery cliffs, continuously wet by water flow. The species is found to grow along with I. verticillata and Fimbristylis spp. in the near vicinity.
Conservation status. The species was scattered in 3-4 population with 7-10 individuals per population. The population is well conserved without any disturbance as it was obtained from the interiors of protected forest. However, considering the lesser   number of populations distributed across hardly 0.5 km, the species is assessed here as Critically Endangered (CE) by applying the criterion d (IUCN 2019).
Other notes. Impatiens shailajae belongs to section Tuberosae, characterized by many-flowered racemose inflorescence; capsule clavate or linear, seed ellipsoid or ovoid and lateral sepals 4 with inner 2 fully developed (Yu et al. 2015). Impatiens shailajae also shares similarity with I. scapiflora but is distinct with respect to the color and shape of papillae on the standard petal, tuberous stolon and trichomes on the leaf. Further, the shape of dorsal petal and its keel is distinct in this new taxon which is easily visible at first glance. All these character combinations along with its undisturbed habitat (localized distribution) and micromorphology (prominent seed hair banding pattern and pollen morphology) further support the status of newly described species.