Introduction
Phyllanthus L. (Phyllanthaceae) is represented by c.833 species in tropical and subtropical regions of the world (Govaerts et al., Reference Govaerts, Frodin and Radcliffe-Smith2000), with 51 species and two varieties found in India (Chakrabarty et al., Reference Chakrabarty, Gangopadhyay, Balakrishnan, Balakrishnan, Chakrabarty, Sanjappa, Lakshminarsimhan and Singh2012) of which 18 species and one variety are endemic. The critically endangered Phyllanthus talbotii has been poorly known taxonomically because earlier works (Webster, Reference Webster1956, Reference Webster1957, Reference Webster1958; Kathriarachchi et al., Reference Kathriarachchi, Samuel, Hoffmann, Mlinarec, Wurdack, Ralimanana, Stuessy and Chase2006) did not treat it, owing to its narrow endemism and lack of herbarium specimens. Finally, in 2007, Balakrishnan and Chakrabarty placed it in Phyllanthus subgenus Eriococcus (Hassk.) Croizat & Metc. (Balakrishnan & Chakrabarty, Reference Balakrishnan and Chakrabarty2007).
Phyllanthus talbotii was described by L. J. Sedgwick in 1921 from collections made at Jog Falls, Shivamogga district, Karnataka in 1883 by Talbot and in 1919 by Sedgwick & Bell, and at Supa, Uttara Kannada district, Karnataka in 1918 by Sedgwick & Bell. After a lapse of about five decades this species was rediscovered in 1969 by Raghavan at Agumbe Ghat, Shivamogga district. Subsequent surveys of this locality revealed, however, that it was no longer extant here so the species was listed in the Red Data Book of Indian Plants (Nayar & Sastry, Reference Nayar and Sastry1990). Later, in 1997 and 2010, the species was relocated in a few localities in Sanguem Taluka, South Goa district, Goa, near streams (Naik et al., Reference Naik, Pagare, Krishnan and Janarthanam2013). During an assessment of the endemic and threatened angiosperm taxa of the northern Western Ghats in Goa, Karnataka and Maharashtra from 2007 to 2012, an intensive search was carried out to locate Phyllanthus talbotii in the entire area. The existence of the species was confirmed in a few localities of Sanguem Taluka, South Goa district and, in 2012, during these surveys, it was also discovered in a new locality in Netravali Wildlife Sanctuary, South Goa district with an extant population of c.80 individuals. Phyllanthus talbotii is currently confined to the South Goa district of Goa state, having been lost from all previously recorded localities in Karnataka. These localities are all near to each other and exhibit narrow endemism within their confines.
The habitat-sensitive Phyllanthus talbotii thrives in the rocky beds of rivulets, streams, waterfalls and along the banks of reservoirs in the northern Western Ghats regions of Goa and formerly in Karnataka. Such a specific habitat is susceptible to alteration, with recurrent floods and anthropogenic pressures, which is probably one of the causes of its disappearance from its type localities as well as the rediscovered locality of 1969. The extant populations at Sanguem Taluka and the new site at Netravali Wildlife Sanctuary are exposed to similar threats which are detrimental to the survival of the species in nature. The exact causes of decline of this species in nature are the subject of further research.
After Phyllanthus talbotii was collected at the new site at Netravali Wildlife Sanctuary, the species was critically studied taxonomically and it was found necessary to select a lectotype. In carrying out this lectotypification, we have followed the guidelines of Art. 9.2 of the Melbourne Code (McNeill et al., Reference McNeill, Barrie, Buck, Demoulin, Greuter and Hawksworth2012).
Taxonomy
Phyllanthus talbotii Sedgw., J. Indian Bot. 2: 124, f. 2 (1921) (as ‘talboti’); M.P.Nayar & Sastry, Red Data Book Indian Pl. 3: 124 (1990); N.P.Balakr. & Chakrab., Fam. Euphorbiaceae India 374 (2007); N.P.Balakr. et al., Fl. Ind. 23: 461 (2012); S.S.Naik et al., Rheedea 23: 16 (2013). – Type: India, Karnataka, Shivamogga district, Gairsoppa Falls (now Jog Falls), 20 xi 1883, W.A. Talbot 828 (lecto BSI [barcode BSI-0000000352], designated here). Figs 1, 2.
Phyllanthus talbotii Sedgw.
Lectotype of Phyllanthus talbotii Sedgw. (BSI-0000000352, © Botanical Survey of India, WRC, Pune, India).
Subshrub, 1–1.6 m tall, monoecious; stem terete, woody up to middle region; leaf-bearing branchlets 8–30 cm long, puberulous when young, glabrescent. Leaves oblong, 4–8.5 × 2–3.5 mm, apiculate or shortly acuminate apically, rounded basally, thinly puberulous on both surfaces, mid nerves prominent, lateral nerves obscure; petioles 0.5–1 mm long, puberulous; stipules lanceolate-deltoid, 1.5–2.5 × 0.9–1.2 mm. Staminate flowers solitary or in clusters of 2 or 3 at the proximal axils, 2–2.5 × 1.8–2.1 mm; pedicels 1.5–2.5 mm long, capillary, slightly dilated at apex; bracts lanceolate-ovate, 1.5–2 mm long; bracteoles subulate, 0.7–0.9 mm long; sepals 2+2, obovate-orbicular, 1.9–2.1 × 0.9–1.3 mm, acute to rounded at apex, white with light purplish tinge in middle, wavy along margins; petals absent; disc glands 4, capitate, 0.15–0.25 mm long, yellow; staminal column 0.5–0.6 mm long; anthers 4, in two pairs, 0.3–0.4 mm diam., yellow. Pistillate flowers solitary, axillary, 2.5–3 mm diam.; bracts and bracteoles as in staminate flowers; pedicels 3–4 mm long, dilated at apex; sepals 3+3, ovate, 1.5–2 × 0.9–1.3 mm, white with light greenish or purplish tinge in middle, wavy along margins; petals absent; disk 0.6–1 mm diam., annular, slightly 5-lobed, greenish yellow; ovary 0.5–0.7 mm diam., 3-lobed, shortly stipitate; styles 3, 0.5–0.6 mm long, free, deeply bifid above, appressed to ovary. Capsules 2.5–3 × 3.5–4 mm, subglobose, distinctly 3-lobed, invaginated at apex, stipitate, hirsute, green; cocci 3. Seeds 2 in each coccus, 3-angled, 1.6–1.8 × 0.9–1.1 mm, smooth, brown.
Flowering and fruiting. August–December.
Distribution. Formerly endemic to the states of Goa (South Goa district) and Karnataka (Shivamogga and Uttara Kannada districts) in India. Presently restricted to South Goa district, Goa state.
Habitat. Grows in rocky beds of rivulets, streams of waterfalls and along water reservoirs of dam sites in northern Western Ghats regions of Goa and Karnataka.
Conservation measures. (1) Anthropogenic activity in riverbeds should be avoided as the first step to safeguard the extant population. (2) Seed dormancy and viability experiments are required to check the causes of failure of germination under ex situ conditions. (3) Propagation through culture techniques, acclimatisation and reintroduction of juvenile plantlets in natural habitat is suggested, followed by monitoring until they establish.
IUCN threat status. Field observation from 2007 to 2012 showed that Phyllanthus talbotii is localised in South Goa district of Goa state within some 5 km2 area of occupancy. Using the IUCN guidelines of 2013 (IUCN Standards and Petitions Subcommittee, 2013), Phyllanthus talbotii is categorised as Critically Endangered [B2b(ii,iii) c(ii,iii)].
Additional specimens examined. India. Karnataka: North Kanara, xi 1918, Sedgwick & Bell 4869 (BLAT); North Kanara, xi 1919, Sedgwick & Bell 7073 (BLAT, 2 sheets). Goa: South Goa district, Sanguem, ix 1997, Joshi & Rajkumar 1022 & 1070 (Goa University Herbarium); Selaulim dam site, viii 2010, Naik 4001 & 4002 (Goa University Herbarium); Collem stream, ix 2010, Naik 4003 & 4004 (Goa University Herbarium); Waddem stream, x 2010, Naik 4005, 4006 & 4007 (Goa University Herbarium); Dudhsagar waterfalls, xi 2010, Naik 4008, 4009 & 4010 (Goa University Herbarium); Netravali Wildlife Sanctuary, xii 2012, R.Kr. Singh 185299 (BSI).
In the protologue of Phyllanthus talbotii, Sedgwick (Reference Sedgwick1921) cited three gatherings, ‘In fluminibus Canarae in Provincia Bombaiensi, apud Supa, Sedg. et Bell 4869, Nov. 1918, et apud Jog (Gaisoppa) Talbot 828, A.D. 1883, Sedg. et Bell 7073, Nov. 1919’, but, in keeping with the practice of the time, he did not designate a holotype. Sedgwick’s herbarium is in the Blatter Herbarium (BLAT) in St Xavier’s College, Mumbai where one sheet of Sedgwick & Bell 4869 and two of Sedgwick & Bell 7073 have been located. One sheet of Talbot 828 has been found at BSI. Of these, Talbot 828 (BSI) is designated here as the lectotype as it agrees well with the protologue and is the best preserved. Sedgwick evidently believed this specimen to represent his new species because he used the collector’s name Talbot as the epithet.
Although Raghavan (Reference Raghavan1969) reported the occurrence of Phyllanthus talbotii at Agumbe Ghat, Shivamogga district, Karnataka, no specimens can be found to verify this statement.
Acknowledgements
The authors thank the Director, Botanical Survey of India (BSI), Kolkata and Head of Office, BSI, Central Regional Centre, Allahabad for access to facilities and the curators of BLAT, BM, BSI, CAL and K for information and images of type specimens. We are most grateful to the Forest Officials of Goa, Karnataka and Maharashtra for their generous support during field surveys.
