Updated distribution of seven Trichosanthes L. (Cucurbitales: Cucurbitaceae) taxa in India, along with taxonomic notes

: In India, lack of revisionary work in the genus Trichosanthes L. (Cucurbitales: Cucurbitaceae) over the past 38 years had resulted in several taxonomic and nomenclatural issues, which had implications in determining actual distribution status of taxa. Based on field observations, collected specimens, data from various specimens in herbaria and critical study of all the resources available, here we confirm the extended distribution of T. anaimalaiensis Bedd. in the states of Manipur and Nagaland; T. cordata Roxb. in Uttar Pradesh and Bihar; T. cucumerina L. subsp. sublobata (Kundu) K. Pradheep, D.R. Pani & K.C. Bhatt in Gujarat, Madhya Pradesh and Odisha; T. dicaelosperma C.B. Clarke in Nagaland; T. kerrii Craib in Arunachal Pradesh and Manipur; T. majuscula (C.B. Clarke) Kundu in Arunachal Pradesh, Sikkim and Assam; and T. truncata C.B. Clarke in Nagaland. Two taxa, namely, Trichosanthes dicaelosperma and T. majuscula , earlier subsumed with T. ovigera Blume or T. cucumeroides (Ser.) Maxim., and T. dunniana H. Lév., respectively, have been resurrected at the rank of species. Lectotypes were designated for the names of above two species. For the first time, female plants of T. majuscula have been described. This communication provides an updated distribution status of seven taxa of Trichosanthes in India along with field and taxonomic notes, and additional taxonomic characters.


INTRODUCTION
Known as the largest genus in the family Cucurbitaceae, Trichosanthes L. consists of about 100 species with some having vegetable and medicinal importance, occurring from the Indian subcontinent in the west, to China and Japan in the north and the east, to Australia in the south (de Wilde & Duyfjes 2010, 2012. Chakravarty (1982) and Renner & Pandey (2013) had reported the occurrence of 22 species in India, with more than three-fourths occurring exclusively in the northeastern region of India. Incomplete herbarium collections in species-rich areas, dioecy, nocturnal flowering, heterophylly, and different juvenile morphology, together with the lack of recent revisionary works (since 1982) had resulted to taxonomic misidentifications and nomenclatural instability in the Indian taxa, which in turn led to non-detection of species in a given area, although present. Reporting of extended distribution of wild species related to crop species not only helps updating the floristic databases of the concerned region, but also in augmenting unrepresented germplasm from such regions for conservation and sustainable utilization (Pradheep et al. 2011(Pradheep et al. , 2018.

MATERIALS AND METHODS
This study was based on extensive survey and explorations (23 trips) carried out all over India during 2009-2020 and herbarium studies. Senior author had personally visited various Indian herbaria -ASSAM, BSD, BSHC, BSIS, BSJO, CAL, CUH, DD, KASH, LWG, MH, NEHU, NHCP, PBL, PCM, and RHT [herbaria codes according to Thiers (2020, continuously updated)]. Species geographic occurrence data from the Global Biodiversity Information Facility (GBIF) and various online herbaria -A, B, BM, BR, E, G, HIFB, FRLHT, GH, HBG, IIIM, JCB, K, KFRI, L, LINN, MO, NY, P, PE, and RPRC [herbaria codes according to Thiers (2020, continuously updated)], including type specimens were also consulted. All the specimens cited here were seen either as physical specimens or in the form of online digital images. Detailed observation on qualitative and quantitative characters was made and herbarium specimens were prepared as per standard procedure (Jain & Rao 1977). Thorough verification or cross-checking with floristic as well as other key literature pertaining to the concerned state (Table 1) and other pertinent works (Jeffrey 1980(Jeffrey , 1982Chakravarty 1982;Naithani 1990;Renner & Pandey 2013;Pradheep et al. 2014Pradheep et al. , 2015Pandey et al. 2016) was made and the status of species distribution was updated. This resulted in identification of seven Trichosanthes species with extended distribution in various Indian states. While herbarium vouchers of these species were deposited in the National Herbarium of Cultivated Plants (NHCP) at ICAR-National Bureau of Plant Genetic Resources (ICAR-NBPGR), New Delhi, germplasm collections are being conserved in the form of (live) seeds in the National Genebank at ICAR-NBPGR, New Delhi.
Flowering and fruiting: May-September and August-November, respectively.
Habitat: Evergreen broad-leaved forests up to 1,600 m; found in red lateritic soils.

J TT
to female, hence retaining bracts; such a kind of sex reversal is of common occurrence in Cucurbitaceae in general, and Trichosanthes in particular (Rugayah 1999).
In natural conditions as well as in herbaria, authors have come across such tendency in other species too ̶ T. costata Blume, T. cucumerina subsp. sublobata, T. dicaelosperma, T. longispicata Rugayah, T. pilosa Lour., T. quinquangulata A.Gray, T. majuscula and T. tricuspidata Lour. This species is well distinguished from T. bracteata (Lam.) Voigt through tomentose nature of leaves (at lower surface), prominent probracts, pinkishred flowers, highly laciniate bracts and male sepals, and oblong seeds. In herbarium specimens, dried leaves appear dark brownish-red in colour. Although C.B. Clarke (l.c.) (later Kundu 1943) agreed that T. palmata var. tomentosa deserves to be a good species with stable diagnostic characters, it appears that Clarke was unaware of T. anaimalaiensis, the species which had been published some 15 years back, therefore rule of priority favours latter as the accepted taxon. In agreement with Chakravarty (1959), type specimen (male specimen) study confirms the synonymization of T. burmensis and its var. alba with var. tomentosa (= T. anaimalaiensis); however ovoid-oblong fruit shape as mentioned in former's protologue indicates the possibility of erroneous choice of female specimens by Kundu in his herbarium-based study. Renner & Pandey (2013) mentioned its distribution in Andaman & Nicobar Islands, which is clearly outside its distributional range. A live collection (IC587669) at ICAR-NBPGR Base Centre, Cuttack, originally from Mayurbhanj district of Odisha had a close similarity with this species.
Flowering and fruiting: May-September and August-November, respectively.
Flowering and fruiting: August-September and October-November, respectively.
Habitat: In herbaria, it was mentioned to have a common occurrence in wastelands and gravelly rocky areas, up to 400 m.
Flowering and fruiting: August-September and September-November, respectively.
Distribution: India (Arunachal Pradesh, Sikkim, West Bengal (Darjeeling) and Meghalaya; new to Nagaland (Figure 1) Maxim., whereas Grierson & Long (1991) kept under southeastern Asian T. ovigera Blume. In agreement with Chakravarty (1982), here we recognise T. dicaelosperma as a distinct species owing to unlobed leaves, globose fruits, scarlet-red pulp and flat subquadrate seeds. Immature fruits emanate odour similar to that of snake gourd. Renner & Pandey (2013), Chakravarty (1982) and Khanna et al. (1999) reported its occurrence in Uttar Pradesh, which is clearly out of its distribution range and no authentic specimens available to substantiate. Though type specimens (CAL0000015132, K000742692) and other specimens (K000742694, L2988267, P03693959) were collected from Khasi Hills of Meghalaya some 150 years back, sincere efforts made to locate this species in original habitats were futile, possibly due to the extensive changes in landscape over the years; also not a single collection available in various herbaria visited. In Arunachal Pradesh, Hajra et al. (1996) reported this species only from Kameng, however we found its common occurrence in eastern parts of the state, i.e., Anjaw, Dibang Valley, and Lohit districts.
Notes: Out of available syntypes (K000742686, K000036897 and P06393544), former two were selected as lectotype and isolectotype (following Articles 9.3. and 9.12. of ICN;Turland et al. 2018) since Clarke himself annotated on these sheets as "Trichosanthes multiloba Miq. var. majuscula", in addition, they depict inflorescence characters such as thick and woody rachis, flowers borne from near the base, all of taxonomic value. This distinct species was originally described at reduced rank under a Japanese species T. multiloba, thereafter kept under T. wallichiana by A. Cogniaux (l.c.), later on synonymised under T. dunniana H. Lév. by Jeffrey (1982), which was adopted by Huang &Jeffrey (2011) andRenner &Pandey (2013). Probable reason for this confusion is the lack of details on female flowers, fruits and seeds. It is easily distinguished from T. wallichiana by membranous leaves (vs. chartaceous), small ovate probracts (vs. much elongate), shorter peduncle of male inflorescences (vs. very long), serrate male bracts (vs. laciniate), ovate-oblong fruits (vs. globose) and dark Image 6. Herbarium specimen of Trichosanthes majuscula from Assam at CAL. © Director, BSI, Kolkata.  (2004)).
Flowering and fruiting: May-August and June-October, respectively.
Occurrence in India: Arunachal Pradesh, Assam, Meghalaya, Sikkim, West Bengal; new to Nagaland (Figure 1) Chakravarty (1982) and Renner & Pandey (2013) mentioned this species from Andhra Pradesh which is outside its distribution range. Though type specimen was collected from Khasi Hills (almost 150 years ago), no further collections available thereafter and now failed to locate this species due to the extensive topographic change. This species could be a connecting link between Trichosanthes and Hodgsonia Hook.f. & Thomson owing to the distinct characters ̶ big chartaceous leaves, yellowish-white flowers, bigsized fruits as well as seeds, and whitish mesocarp and pulp. Hajra et al. (1996) mentioned its occurrence from Kameng, Subansiri and Tirap in Arunachal Pradesh; however, we noticed it occasionally in Lohit district as well.

Threatened Taxa
Author details: Dr. K. Pradheep is presently working as Principal Scientist at ICAR-NBPGR Regional Station, Thrissur, He is involved in Plant Genetic Resource (PGR) management activities in general, and germplasm collection and taxonomic studies in crop taxa, in particular. He has documented the Crop Wild Relatives (CWR) occurring in India. Mr. Soyimchiten is working as Scientist at the Division of Plant Exploration and Germplasm Collection, ICAR-NBPGR, New Delhi. He is specifically involved in collecting crop and CWR germplasm from all over the country. Dr. G.D. Harish is working as Scientist & Officer-in-Charge at the ICAR-NBPGR, Regional Station, Shillong. He is working on the PGR management activities such as germplasm collection from northeastern states of the country, their conservation and evaluation at Shillong. Dr. M. Abdul Nizar superannuated from service at ICAR-NBPGR, Regional Station, Thrissur. He has worked mainly on the PGR management activities such as germplasm collection from peninsular states of the country, their conservation and evaluation at Akola and Thrissur. Dr. K.C. Bhatt is working as Principal Scientist at the Division of Plant Exploration and Germplasm Collection, ICAR-NBPGR, New Delhi. He is specifically involved in collecting crop and CWR germplasm from all over the country. Dr. Anjula Pandey is working as Principal Scientist at the Division of Plant Exploration and Germplasm Collection, ICAR-NBPGR, New Delhi. Besides, being the curator of National Herbarium of Cultivated Plants (NHCP), she is specifically involved in collecting crop and CWR germplasm and taxonomic research and teaching. Dr. S.P. Ahlawat is working as Head of the Division of Plant Exploration and Germplasm Collection, ICAR-NBPGR, New Delhi. He is coordinating exploration activities of ICAR-NBPGR, in addition to the involvement in the collecting of crop and CWR germplasm.