Tragia liberica Jongkind, 2015

Jongkind, Carel C. H., 2015, Tragia liberica Jongkind (Euphorbiaceae), a new forest species from Liberia, Candollea 70 (2), pp. 249-252 : 250-252

Tragia liberica Jongkind , spec. nova ( Fig. 1 , 2 ).

Typus: LIBERIA. Sino County: east of Greenville-Zwedru road, 5°20.66’N 8°53.20’W, 117 m, 25.IX.2013, fl. fr., Jongkind, de Wet & Sambolah 12145 (holo-: BR!) .

Tragia liberica Jongkind differs from its most similar congener, T. preussii Pax , by its acute, not cordate, leaf blade base and by only two pairs of lobes on the female sepals instead of 3-4 pairs.

Twining, woody climber, less than 1 m high. Twigs pilose. Leaves alternate; blade 6-17 × 2-4.5 cm, obovate, papery, with 8-11 pairs of main lateral nerves, apex acuminate, base very narrowly rounded-cuneate, margin irregularly serrulate with tooth apex minutely glandular, upper surface only hairy on the midrib, lower surface hairy on smaller nerves as well; petiole 3-25 mm long, pilose; stipules 5-7 mm long, triangular, with a few scattered hairs. Inflorescence a leaf-opposed, lax, short hairy, raceme, up to 14 cm long, with the first flower (the only) female and many male flowers higher up, bracts at the base of the pedicel, 3 subtending proximal flowers, one subtending distal flowers. Male and female flowers green and yellow. Male flowers with pedicel ca 3 mm long; 1 or 3 bracts up to 1.5 mm long, lanceolate; 3 sepals ovate, 1 mm or less long, glabrous, valvate, closed in bud; petals 0; stamens 3, alternating with sepals; anthers ca 0.3 mm long; filaments very short. Female flowers with pedicel ca 2 mm long, pale hairy; middle bract ca 2 mm long, ovate, side bracts shorter, lanceolate; sepals 6, ca 2 mm long, pinnatisect, with 2 slender lobes at each side, ending in a lobe of comparable shape and size, with the rachis about as wide as the lobes, with only few hairs; ovary 3-locular, densely short setose; styles in a stout column, glabrous, free above. Capsule 3-coccous; 3 bivalved mericarps separating from the columella, mericarps enclosing the seeds; sepals and pedicel somewhat enlarged in fruit; seeds 3, ca 3 mm in diameter, subglobose.

Distribution and ecology. − Undergrowth of evergreen forest, below 150 m altitude. Only known from Liberia.

Conservation status. − Tragia liberica is an inconspicuous plant that can easily be overlooked. With the only two known locations ca 300 km apart it is likely that it still can be found in evergreen forest in between. The species has not been found yet in a protected area but could occur in Sapo National Park, the south-eastern collecting location is close to this protected forest area. Considering all the economic development planned and in progress in the forests of Liberia, “Vulnerable” [VU C2a(i)] would be the appropriate status until more is known. Calculating its “Extent of Occurrence” and “Area of Occupancy” ( IUCN, 2012) does not make sense in this case without a special search for the species in forest in Liberia where it still may be expected.

Notes. − Most African Tragia species have irritating hairs in leaves, twigs and/or inflorescence. This character, that is usually very conspicuous, was not noted in the field for the two specimens of the new species. Stinging hairs are, according to KEAY (1958: 411), absent in T. preussii , another species from wet evergreen forest. It is not clear if the stinging hairs are really absent or maybe too small to have an effect on the human skin.

All herbarium specimens of Tragia from Liberia are mapped here ( Fig. 2 ), the new species is the only Tragia in Liberia that is found in the wet evergreen forest. The evergreen forest in Liberia is mainly confined to a belt of variable width from north-west to south-east starting close to the ocean and changing to drier forest, like semi-deciduous forest, more inland (a reliable vegetation map of Liberia does not exist.) Tragia plants are not very conspicuous and are probably more common than can be concluded from this distribution map but the pattern is obvious even with this small number of specimens. The other specimens from Liberia are not all identified to species level but are all of species with a conspicuous cordate to narrowly cordate-acute leaf blade base, such as T. mildbraediana Pax & K. Hoffm. , T. spathulata Benth. , and T. tenuifolia Benth. These three Tragia spp. are also known from the forest in Sierra Leone, Ivory Coast and Ghana and grow there in forest with a lower rainfall than where T. liberica is found.

Paratypus. – LIBERIA. Boporo District: Bangee , 16.XI.1947, Baldwin 10353 ( K, WAG).

Figures

Fig. 1. – Tragia liberica Jongkind.A. Habit with inflorescences; B. Leaf margin from below; C-D. Leafbase and stipules; E. Female flower with bracts; F. Male flower with bract; G. Male flower in cross-section; H. Lower part of pedicel and bracts after male flower dropped;I. Developing fruit; J. Female sepal; K. Large bract from I; L. Columella and sepals after dehiscence of the fruit; M-O. Mericarp of split capsule with enclosed seed from three different angels. [A-C, E-H, L-O: Jongkind 12145, BR; D, I-K: Baldwin 10353, WAG] [Drawing: Hans de Vries]

Fig. 2. – Distribution map of Tragia liberica Jongkind (squares) also showing all other Tragia L. specimens (stars) from Liberia from the BR, K, P and WAG herbaria.