Rubus micropetalus Gardner (1848: 6)

Narayanan, Bhavadas, Prabhukumar, Konickal Mambetta, Kumar, Vannaratta Veetil Naveen, Harinarayanan, C. M., Chinnappan, Satheshkumar & Umesh, Balakrishnan Thara, 2023, Taxonomic delineation of two closely allied Rubus L. (Rosaceae) species with notes on the typification of the name R. fairholmianus, Phytotaxa 622 (5), pp. 271-280 : 275-279

Rubus micropetalus Gardner (1848: 6) . Figure 3

Type (Lectotype designated by Narayanan and Umesh, 2018): Sri Lanka, Ellia plains , 6000 ft. G. Gardner 263 ( K barcode no. K000737927 [digital image!]. Isolectotype, K barcode no. K000737929 , K000737930 [digital image!], BR barcode no. BR0000005294473 [digital image!] and BM (barcode no. BM000622290 ) [digital image!]) .

Synonym: R. moluccanus auct. non L.: Hook.f. (1878: 330), Pro Parte.

Vernacular name: Kattumunthiri ( M).

Straggling shrub with 3–6 m long. Stem terete, mature stem woody, green, glabrescent, glaucous, young twigs covered with short hairs with fulvous tomentum; prickles stout, irregularly arranged on the stem, 1–2 mm long, downwardly curved. Stipules adnate to stem, caducous, 8–14 mm long, linear, base round, margin pectinately elongated with 7–10 bristles, slightly pubescent on adaxial surface and densely pubescent on abaxial surface. Leaves simple, usually 3-lobed, sub-lobes absent, sub-chartaceous, terminal lobe very much larger, apex acute or obtuse; basal and lateral lobes acute, very often round. Petiole terete, 2–8 cm long, fulvous tomentum with golden yellow; prickles few, c. 1 mm long, curved downwards. Lamina of the leaves 7–13.5 × 4.5–7 cm, lanceolate, ovate or ovate-lanceolate, base cordate or sub cordate, margin serrate, apex acute or obtuse or round, distantly rugose, glabrescent with hirsute on the main nerves on adaxial surface and pubescent on abaxial surface with golden yellow beneath; prickles present on abaxial surface, yellow, c. 1 mm long, curved downwards. Blades of leaves penninerved with 6–8 pairs of veins, brochidodromous; midrib and lateral veins more raised below. Inflorescence in short cluster, branched raceme with 5–18 flowers, axillary or terminal in position, 8–10 cm long, compactly arranged; peduncle 1.5–2.5 cm long, terete, fulvous tomentum with glaucous; prickles minute, c. 1 mm long, downwardly curved. Flowers white, bisexual and actinomorphic. Bract persistent, 6–6.5 mm long; linear in outline with 2–3 bristles at apex, base round, margin entire, sparsely pubescent on adaxial surface and densely pubescent on abaxial surface, slight green beneath. Pedicel 0.5– 1.5 cm long, terete, pubescent. Sepals 5, free, 6–6.5 × 4–4.3 mm long; sub-equal, elliptic or ovate-lanceolate, base round, margin distinctly serrated at outer calyx and entire at inner calyx, apex acute or short acuminate, pubescent adaxially, sparsely pubescent abaxially. Petals 5, free, deciduous, 2.8–3 × 2.2–2.4 mm long; obovate, margin entire and irregularly incised towards apex, apex acute, white, glabrous, petals less than half the length of calyx lobes. Stamens numerous, dorsifixed; filaments 3.5–4 mm, narrowed towards apex, creamy; anther 2-celled, 0.8–1 mm, oblong, white. Carpels numerous; ovary 1.2–1.4 mm, ovoid, glabrous; style 3.3–4 mm, white-creamy, glabrous; stigma entire. Fruits aggregate of drupelets; 0.8–1.2 cm diam., globose; drupelets numerous, red fruit turned to black purple in mature.

Seed Morphology ( Figure 4 , D– F): —The seed colour red to black, and the proximal end towards ovary wall is oval and narrower towards the distal end; Seeds are prolate ( P / E ratio- 1.84 mm) with ovate or balloon shape in outline, polar view is asymmetric; Seed size 3.06 × 1.67–2.98 × 1.60 mm; micropylar end is broader than central and chalazal end; Seed stratification is irregularly reticulated with deep reticulum lumen having very thick and sharp muri; Lumen microreticulae, irregular in shape, poses uneven distribution on seed surface; Muri is uniformly ribbed at dorsal surface and fairly present on raphe region; Raphe is broader at apical end. Peripheral region not incised.

Phenology: —Flowering and fruiting observed during June–October.

Distribution: —The native range of species is India and Sri Lanka (POWO 2023). In India, the distribution is restricted to Kerala and Tamil Nadu states.

Habitat and Ecology: — Rubus micropetalus is generally found in evergreen and shola forests at an elevation of 1000–2000 m. It grows in upper montane zone, under growth of forest, under slight shade, along roadside and shola grassland ecotone.

Chromosome Number: —2n=14 ( Thompson 1997).

Specimen Examined: — Sri Lanka. 1 January 1854, Thwaites G . H .K. 1536 (P, BM). India. Kerala: Cannannore District, Chandanathode , 24 February 1979, V . S . Ramachandran 61393 ( MH); Cannannore District, Chanadarathode , 800 m, 17 June 1979, V . S . Ramachandran 62645 ( MH); Cannannore District, Chanadarathode , 790 m, 15 February 1978, V . S . Ramachandran 53974 ( MH); Palghat District, Silent Valley R . F ., 1050 m, 15 July 1969, E . Vajravelu 32118 ( MH); Palghat District, Silent Valley R . F ., 950 m, 10 October 1965, E . Vajravelu 26092 ( MH) ; Calicut District, Chedaleth , 925 m, 13 May 1965, J . L . Ellis 24102 ( MH). Idikki District, Panchakanam , 850 m, 22 September 1972, B . D. Sharma 40833 ( MH); Kattappana, Idukki District , 975 m, 28 September 1981, C . N . Mohanam & B . R . Ramujam 72058 ( MH); Puliyanmala, Idukki District , 975 m, 23 March 1981, V . S . Raju 71165 ( MH); Kursimala , 900 m, 13 September 1984, V . S . Antony 760 ( MH); Kottayam District, Deviculam, Munnar Road , 1620 m, 7 April 1963, N . C . Rathakrishnan 16250 ( MH); Trivandram District, Way to Chemnugi , 1275 m, 8 March 1979, M Mohanan 61714 ( MH); Trivandram District, Way to Chemnugi , 1350 m, 18 May 1979, M Mohanan 61814 ( MH); Tamil Nadu: Bethaji Shola, Kolegal, Coimbatore District , 4700 ft, 9 July, 1936, V Narayanswami 3765 ( MH); Muthunkuzhivayal, Kanyakumari District , 1500 m, 27 August 1976, A . N . Henry 47576 ( MH); Deviar Estate, Sethur Hills, Ramanathapuram District , 1200 m, 12 March 1980, S . R . Srinivasan 65917 ( MH); Kalivayalijol, Tirunelvelly, 31 May 1901, 3017 ( MH); Kalivayalijol , Tirunelvelly , 1 June 1901, 3042 ( MH); Tirunelvelli District , Way to Naterikal , 21 September 1967, 1300 m, E . Vajravelu 29282 ( MH); Kerala: Thiruvanthapuram district, Agasthyamala , 14 May 1988, N . Mohanan 9727 ( CALI). Tamil Nadu: Thalakaveri , 10 December 1989, V . K . Mini 2419 ( CALI). Kerala: Pathanamthitta, Gavi , 21 January 2018, N . Bhavadas 11785 ( CMPR). Tamil Nadu: Nilgiri, Kothagiri , 27 December 2016, N . Bhavadas and V . V . Naveen Kumar, 11771 ( CMPR) .

Notes on the occurrence of R. moluccanus L. in Western Ghats: Many species of Rubus such as R. fairholmianus , R. micropetalus , R. macrocarpus etc. were synonymised under R. moluccanus L. by Hooker, in his flora of British India (1878: 330). But he had also mentioned that the position of the names was uncertain, the statement is that “ I am quite unable to arrange the forms of this common and protean plant under recognisable varieties answering to its synonymy ”. Later, Focke, in his monograph of the genus Rubus (1911), resolved the identities of these taxa and confirmed that the distribution of R. moluccanus is native from Ambonia and distributed to Himalayan regions, Sri Lanka, southern China, Philippines, Malesia and north-eastern Australia. The literature also states that, Ambonian specimen is closely matches with large series of specimen in the herbarium of the Bureau of science of various parts of the Philippines and few specimens from Borneo and Java ( Merrill 1917). Perusal of Rumphiun figure and description provided in the protologue, it is revealed that R. fairholmianus , R. micropetalus and R. macrocarpus are distinct from the typical R. moluccanus and the latter is not distributed in Western Ghats of India.

Taxonomic note: —While working on species R. micropetalus and R. fairholmianus in southern Western Ghats, we found several characters (shrubby habit, simple leaf with lobulated leaf lamina, presence of white glaucous on stem, similar flower and fruit colour, small petals etc.) are overlapping between them even after the description provided by Focke (1911). During the study, we confirmed that, both the species are unique and distinct in many morphological attributes, which are provided in Table 1 .

Figures

FIGURE 3. Rubus micropetalus Gardner. A. Habitat; B. Inflorescence; C. Abaxial surface of leaves; D. Flower; E. Fruits; F & G. Stipules (showing adaxial and abaxial surface); H & I. Sepals (showing adaxial and abaxial surface); J. Petal; K & L. Bracts (showing adaxial and abaxial surface); M. Drupelet. (Photos: Bhavadas N).

FIGURE 4. (A–C): Rubus fairholmianus Gardner. A. Surface ornamentation, B. Dorsal side of seed, C. Raphe region. (D–F): Scanning electron micrographs of seed coat of Rubus micropetalus Gardner. D. Surface ornamentation, E. Dorsal side of seed, F. Raphe region.