Euphorbia sahyadrica Sardesai & Malpure, 2021

Malpure, Nilesh V., Raut, Prashant S., Sardesai, Milind M. & De Jong, Bruce E., 2021, Euphorbia sahyadrica (Euphorbiaceae), a new species of succulent shrub from the wet zone of the northern Western Ghats, Maharashtra, India, Phytotaxa 500 (4), pp. 285-293 : 286-291

Euphorbia sahyadrica Sardesai & Malpure , sp. nov. ( Figs.1–3 )

Diagnosis:— Lactiferous, armed succulent allied to E. nivulia but differing in its spreading shrub-like habit, light grey bark with closelypacked horizontal branch scars and fissures, fleshy elliptical leaves with obtuse apices, short petioles, and easily visible lateral nerves, protruding tubercles in a spiral pattern, spine shields bearing two pairs of spines, cymes with short peduncles that usually have a bisexual cyathium in the central position, and capsules with cocci that are tapering laterally and do not have a prominent suture between lobes.

T ype:— INDIA. Maharashtra: Raigad district., Harihareshwar , 18°01.052’N, 73°01.415’E, elev. 53 m, 16 February 2019 , N. V. Malpure 0030 (holotype CAL!; isotypes BSI!, SUK!).

Spreading, profusely branched shrub up to 4(−5) m tall, wider than tall with persisting lower branches. Stem woody, rough, with somewhat compressed spiral rows of spines. Bark silvery grey with persistent scars of tubercles and branches, and with closely packed horizontal fissures. Branches terete, 3–5 cm diam., whorled or not, often nearly horizontal. Tubercles protruding up to 1 cm, arranged in a spiral pattern. Spine shields circular, pale brown when young then becoming ashy grey, each with 2 pairs of spines, the upper pair 1 mm long, sometimes caducous, the lower pair dominant and usually persistent, divergent, 2–5 mm long. Leaves 12−18 × 5−8 cm, subsessile with petiole 0.5–1 cm long, attenuate at base, usually elliptic or obovate, apex obtuse and mucronulate, fleshy, slightly hyaline, margin entire with prominent midvein and visible lateral nerves, falling in dry season, leaving a large light-coloured leaf scar. Cymes 1(−2) per flowering eye, terminal or subterminal, in dichasium, often branching up to two levels, the central cyathium sessile, most often bisexual, lateral cyathia on peduncles, bisexual. Peduncles 0.8−1.2 cm long, 3–4 mm thick, smooth, glabrous, green. Bracts opposite, 2.5–3 × 1.4–2.5 mm, ovate to obtuse, minutely fimbriate, yellowish, sub-keeled. Involucre broadly cupular, 7–10 × 3–4 mm. Glands 5, transversely oblong, 6–7 mm, with a wavy border, convex, yellowish green. Involucral lobes 5, 1.2–1.5 × 1.3–1.6 mm, broadly ovate, fimbriate, quincuncial in bud stage. Male florets in 5 fascicles, 6−7 per fascicle, 1.8–5.0 mm long, subtended by laciniate bracteoles, pedicellate; pedicel 2.0− 3.5 mm long, colourless, shiny, persistent and protruding; filament 1.0− 1.5 mm long, yellow; anther 0.6−0.7 × 0.8−1.0 mm, dull orange to yellow, basifixed, orbicular, longitudinally dehiscent. Female florets: gynophore 2 mm when unfertilised, becoming 1.2−1.5 cm long, recurved when immature, green, perianth lobes 3; ovary trigonous; styles 3, connate up to middle; stigma bifid, papillose. Capsules exserted, trilobed 1.1−1.3 cm diam, smooth, glabrous, green with stippled reddish margins converging on septa, cocci tapering laterally without prominent suture between cocci. Seeds globose c. 5 × 4 mm, blackish grey, mottled with tan spots converging around the medium raphe.

Chromosome number:—2n = approx. 240.

Phenology:— Flowering January–April and fruiting February–May.

Distribution and habitat:— Currently E. sahyadrica is only known in the coastal hills of Raigad District of Maharashtra near Harihareshwar and Alibag. These sites are separated by approximately 100 km (Map 1). The new species grows in shallow soil on the rocky basaltic hills facing the sea. Our survey found more than 150 fully grown individuals within this scrub vegetation habitat. Other species growing in association with Euphorbia sahyadrica were Bombax ceiba L., Carissa carandas L., Cordia myxa L., Grewia asiatica L., Helicteres isora L., Lantana camara L., Leea indica (Burm.f.) Merr., Santalum album L., and Lannea coromandelica (Houtt.) Merr.

MAP 1. Distribution of Euphorbia sahyadrica Sardesai & Malpure (green squares) and Euphorbia nivulia Buch. -Ham.(blue dots).

Additional specimen examined (paratype):— INDIA. Maharashtra: Raigad district, on the way to Varasoli , 18°65.849’N, 72°87.737’E, 15 March 2019, N. V . Malpure 109 (MH!).

Additional specimens of E. nivulia examined:— INDIA. Andhra Pradesh: East Godavari Dt., Ontimamidi Vagu Thed Palandi , Jamladugu, 27 March 1988, N . Rama Rao & T . Ravishankar 86546 ( MH!). Kadappa Dt., Palkonda Hills, 1500 ft, July 1884, J . S . Gamble 14028 ( CAL!). Vishakhapatnam Dt., Kilagada, 9 March 1965, G . V . Subbarao 22577 ( MH!); Jalaput, 7 January 1969, G . V . Subbarao 33306 ( MH!); Simhachalam Hill eastern slope, 6 May 1964, G . V . Subbarao 19379 ( MH!) . Chhattisgarh: Bijapur Dt., Kandla Patri-Indravati Tiger Reserve forest , 20 May 1987, A . Kumar 16278 ( CAL!) . Karnataka: Bagalkot Dt. , Badami, 8 March 1909, S . V . Shevare s.n. ( BSI!). Hassan Dt., Nagpuri Forest , Arasikere, 1 April 2015, R . K . Swamy & A . Singh 0694 ( JCB!). Mandya Dt., Shivasamudram, in dry deciduous forest, 3 March 1978, S . M . Ahamed KFP324 ( JCB!). Shivamogga Dt. [Mysore], Talguppa, October 1908, A . Meebold 7305 ( CAL!) . Kerala: Trissur Dt., Solayar to Malakkampara ghat road, 1300m, 5 February 1984, K . Ramamurthy 80846 ( CAL!) . Madhya Pradesh: Damoh Dt. , Damoh, 2 October 1908, J . R . Parno 29935 ( CAL!). Hoshangabad Dt., Dhupgarh, 430m, 20 August 1949, V . Narayanabirami 3380 ( CAL!). Nimar Dt., 7 December 1907, D. O . Witt 27835 ( CAL!). Sagar Dt., Hirapur, 450m, 3 March 1960, K . Subramaniyam 10171 ( CAL!); Sagar Cantonment, 19 Oct. 1906, A . Blythe 28728 ( CAL!) . Odisha: Khorda Dt., Chandaka Forest , 24 Feb. 2016, A . Singh , R . K . Swamy , N . Page & K . Sankara Rao 0470 ( JCB!). Mayurbhanj Dt., Simlipal Forest , Baniabasa, 23 March 2002, D. D. Bahali & D. K . Agarwala 560 ( CAL!) . Tamil Nadu: Dharmapuri Dt. , Hogenakkal, 14 March 1965, E . Vajravelu 23543 ( MH!); Dharmapuri to Jhalwania, 10 February 1987, M . Prasad 39455 ( CAL!). Kanyakumari Dt., Poovathu Odai, Boothapandy Range via Karumparai Palrulum, 23 February 1983, A . N . Henry 77127 ( CAL!). Nilgiri Dt., Mayar River bank, 16 February 1972, B . D. Sharma 39809 ( MH!). Ramnad Dt., Aiyanar Kovil forest , 12 March 1970, E . Vajravelu 33683 ( MH!). Salem Dt., Chinnakalrayans, 700 m, 20 February 1979, T . S . Jeyaseelan 21871 ( RHT!). Yercaud, 23 March 2016, R . K . Swamy , N . Page , A . Singh & K . S . Rao 361 ( JCB!). Tenkasi Dt., Honey Falls to Courtallam, 20 March 1958, K . Subramanayam 5598 ( CAL!). Tiruchirapalli Dt., Pachaimalais, 1000m, 23 March 1977, D. I . Arockiasamy 7004 ( RHT!); Pachaimalais, 100m, 29 March 1983, K . M . Matthew , S . J . Britto , & N . Rani 29409 ( RHT!). Telangana: Bhadradri Kothagudem Dt. [Godavari], Dummagudem 500ft., February 1885, J . S . Gamble 15196 ( CAL!) . West Bengal: Burdwan Dt., n.d., A . J . Dutt 1163 ( CAL!) .

SRI LANKA. Anuradhapura Dt : Padaviya, Wahalkada Saddle Dam, rocky dry zone forest, 17 August 2014, S. P . Ekanayaka Y14 ( PDA!) .

Conservation status:— A detailed study of the distribution and range of E. sahyadrica has not been conducted. The IUCN redlist category would be DD (Data Deficient) ( IUCN Standards and Petitions Committee, 2019). These plants are somewhat threatened by the presence of nearby touristic activity at Harihareshwar beach and by the presence of grazing animals which endanger seedlings. Though the extant populations appear healthy, our impression is that these plants could later be found to be Vulnerable or even Endangered.

Etymology:— The specific epithet ‘ sahyadrica ’ refers to the northern Western Ghats which are popularly known as the Sahyadris.

Discussion:— Mehra & Choda (1978) carried out cyto-taxonomical studies in the genus Euphorbia and proposed x = 10 as the primary base number. Considering that a wide range of polyploid taxa from 2 n = 12 to 2 n = ca. 200 occur within the genus, Hans (1973) proposed x = 7 and x = 10 as the primary base numbers for the genus Euphorbia . Our cytological studies found that E. sahyadrica has approximately 2 n = 240 chromosomes. The level of ploidy is 24x taking the base number as x = 10. It was noted that E. nivulia samples from both the above locations have only 2 n = 60 chromosomes ( Fig. 4 ). This confirms the work of Mehra & Choda (1978) who reported n = 30 as the chromosome number for E. nivulia .

A side by side comparison of E. nivulia and E. sahyadrica shows a number of distinguishing characteristics that separate the two species ( Table 1).

Figures

FIGURE 1. Comparison of Euphorbia sahyadrica Sardesai & Malpure and Euphorbia nivulia Buch.-Ham. (A–C) Euphorbia sahyadrica Sardesai & Malpure. (A) Habit, (B) Leaves, (C) Spine shield. (D–F) Euphorbia nivulia Buch.-Ham. (D) Habit, (E) Leaves, (F) Spine shield. Photos A–C by Milind Sardesai, D–F by Nilesh Malpure

FIGURE 2. (A–E) Euphorbia sahyadrica Sardesai & Malpure. (A) Flowering branch, (B) Capsules, (C) Involucral lobe, (D) Bract, (E) Seed; (F–J) Euphorbia nivulia Buch.-Ham. (F) Flowering branch, (G) Capsules, (H) Involucral lobe, (I) Bract, (J) Seed. Photos: A–J by Nilesh Malpure.

FIGURE 3. Illustration of Euphorbia sahyadrica Sardesai & Malpure. (A) Habit, (B) Stem and spine shields, (C) Leaf, (D) Cyme, (E) Bract, (F) Bisexual cyathium, lateral view, (G) Bisexual cyathium, top view, (H) Staminate flowers, (I) Involucral Lobe, (J) Capsule, lateral view, (K) Capsule, top view, (L) Seeds, top and lateral view. Illustrated by B. De Jong from N.V. Malpure 0030.

FIGURE 4. Mitotic plate comparison of Euphorbia sahyadrica Sardesai & Malpure (A) and Euphorbia nivulia Buch.-Ham (B).