Rotala juniperina A.Fern. ( Fernandes 1974: 126 )

Prasanth, Arun, Sharma, Oshin A. & Sardesai, Milind M., 2021, New distributional record of Rotala juniperina (Lythraceae) for Asia with typification of three names, Phytotaxa 514 (2), pp. 167-172 : 168-170

Rotala juniperina A.Fern. ( Fernandes 1974: 126) . ( Figs. 1 & 2 )

≡ Rotala decumbens A.Fern. ( Fernandes 1974: 127) .

Lectotype (designated as “Type” by Cook 1979):—AFRICA. Malawi, Mulanje (formerly Mlanje) District, 16 Km N. W. of Likabula Forest Depot , 700 m, 15 June 1962, Robinson 5353 ( SRGH); isolectotypes: BR [ BR0000006259914 !], K [000049162!], M [0106632!].

Description: —Emergent aquatic or amphibious perennial herb. Stems ascending or erect, branched, up to 30 cm long, submerged stems 4-angular or inflated, aerial stems strictly 4-angular with wings. Leaves sessile, decussate or occasionally in whorls of 3, at apex of young branches 1.5–2 × 0.5–0.8 cm, lanceolate, acute at apex and cuneate at base. Bracts foliaceous, 1.5–2.0 × 0.3–0.5 cm lanceolate, smaller in flowering branches; bracteoles 2, linear, scarious, 1.0– 1.5 mm long, as long as the floral tube. Flowers solitary, in axils, monomorphic, born mostly on lateral inflorescence branches. Floral tube campanulate, 1–1.5 mm long at anthesis, up to 2 mm long in fruit, tri-merous, pinkish; calyx 3, shallowly triangular, alternating with 3 calyx appendages, 0.5–1 mm long, exceeding the calyx lobes. Petals 3, elliptic, ca. 0.5 mm long, white, persistent. Stamens 3, inserted below the middle of floral tube. Ovary globose to sub-globose, sessile; style ca. 0.25 mm long; stigma capitate. Capsules subglobose, 1.5–2 mm long, included within the calyx, 3- valved; seeds many, semi-ovoid, up to 0.6 mm long.

Phenology: —August to October

Distribution and habitat: —Africa (East Zaire of Congo, Zambia, Malawi ( Cook 1979, Hyde et al. 2021)) and India (Maharashtra). Plants grow along the fringes of seasonal ponds on lateritic plateaus, muddy roadside and in paddy fields during monsoon, at 600–700 m alt.

Specimens examined: — AFRICA. ZAIRE. Shaba (Katanga), Mitwaba , Simama , Dikuluwe , 12 July 1956, Bryneart 505 ( BR0000016869424 ). ZAMBIA. Kabulamwanda Dam, 108 Km North of Choma, 1150 m, 24 April 1954, Robinson 723 ( K000049163 ). ASIA . PENINSULAR INDIA. Maharashtra, Mahabaleshwar , Venna Lake, 14 October 1957, S . D. Mahajan 24692 ( BSI); Talegaon , 12 October 1956, S . D. Mahajan 8311 ( BSI); Paud , south hill, north slope, 27 October 1956, S. K . Jain 8822 ( BSI); Panchgani Plateau , 13 October 1960, M. Y . Ansari 67730 ( BSI); Junnar , Fagulgahan, 16 October 2003, S. B . Nagarkar 23203 ( AHMA); Pune, Pimpri, 12 September 2020, Arun Prasanth APR14 ( SPPU, CAL); Pune, Lonavala, Plateau above INS Shivaji, 15 September 2020, Arun Prasanth & Milind Sardesai APR017 ( SPPU); Pune, Visapur Fort, 08 October 2020, Arun Prasanth APR24 ( SPPU, AHMA) .

Notes: — Rotala juniperina ( Figs. 1 & 2 ) is so far known only from Malawi and Zambia of Africa and there is no record of collection of this taxon after the type collection in 1962 ( Cook 1979, Hyde et al. 2021). After a gap of more than half-a-century, we collected the specimens of R. juniperina from northern Western Ghats of Maharashtra, India, which constitute a new distributional record for Asia and rediscovery of the taxon. The specimen from India matches the African specimen in accordance with its habit and flower characters. The specimens of R. juniperina from peninsular India were formerly misidentified as R. densiflora (Roth) Koehne (1880: 164) . Although, the herbarium specimens of Asian species R. densiflora and R. cordata Koehne (1880: 172) resemble R. juniperina in exsiccatae, they can be easily distinguished from the latter based on tri-merous flowers. R. juniperina can also be differentiated from R. malampuzhensis R.V. Nair ex C. D. K. Cook ( Cook 1979: 98) on the basis of quadrangular stems and absence of a nectar scale. Recently, R. pseudojuniperina Lekhak & S.R. Yadav (2017: 432) was described from Western Ghats of Maharashtra, India. It is closely similar to R. juniperiana in having tri-merous flowers, included capsules and insertion of stamens below the middle of the floral tube. But R. juniperina differs in following: bracteoles as long as the floral tube 1–1.5 mm long (vs. exceeding the floral tube ca. 3 mm), floral tube 1–1.5 mm long (vs. ca. 3 mm), sepal appendages 0.5–1 mm long, exceeding the sepal (vs. exceeding sepal ca. 1.5 mm), capsule globose (vs. ovoid) and seed semi-ovoid (vs. ellipsoid) ( Lekhak & Yadav 2017).

Figures

FIGURE 1. Rotala juniperina:A. Habit; B. Flowering branch; C-D.Young and mature flower with bracteole; E. Capsule; F. SEM of seed; G. Spermoderm. Scale bars: 3 cm (A); 1 mm (C, D); 0.5 mm (E). Photographs:Arun P.R. and M.M. Sardesai (B).

FIGURE 2. Rotala juniperina: A. Habit; B. Flower with bracteole; C. Flower opened; D. Capsule; E. Seed. Illustrated by- Arun P.R. based on APR014.