Premna bhamoensis Y.T. Tan & B. Li, 2017

Tan, Yunhong, Li, Derong, Chen, Yongjun & Li, Bo, 2017, Premna bhamoensis (Lamiaceae, Premnoideae), a new species from Kachin State, northeastern Myanmar, PhytoKeys 83, pp. 93-101 : 93

Premna bhamoensis Y.T. Tan & B. Li sp. nov. Figures 1 , 2A-C , 3

Diagnosis.

The species is most similar in morphology to P. menglaensis B. Li, but differs from the latter in having branchlets and petioles densely tomentose (vs. glabrous or glabrescent), leaf blades papery with minute pubescence (vs. leathery and glabrous), flowers green to greenish yellow (vs. red flowers), calyces slightly 2-lipped with five equal lobes (vs. calyces distinctly 2-lipped with entire or minute emarginate lips), and stamens exserted from corolla (vs. included).

Type.

MYANMAR. Kachin State, Bhamo County, voucher from a cultivated plant at the Xishuangbanna Tropical Botanical Garden, Menglun Town , Mengla County , Yunnan Province , Alt. 550 m, 21.404408N, 101.152401E, 10 June 2011, B. Li LB0399 (fruiting branches) (holotype: IBSC!; isotypes: IBSC!, JXAU!, HITBC!) .

Description.

Woody shrubs, climbing. Branches brown, terete, with an interpetiolar ridge and sparse small yellow elliptic lenticels, sparsely and minutely pubescent to glabrescent. Branchlets grayish to brownish, densely tomentose, without bracts at the base. Leaves simple, opposite-decussate, ovate-oblong to elliptic, papery, 9.0-17 × 4.5-7.5 cm, apex long caudate to caudate-acuminate, base cuneate, subrounded to slightly cordate, margin entire; adaxial surface subglabrous except minutely hirsute on veins; abaxial surface densely pubescent with sparse, yellowish-brown glands; veins 4-8 pairs, abaxially raised and adaxially slightly compressed, secondary veins curved and jointed near margin; petiole 1.5-4.5 cm long, furrowed on upper part, densely yellowish-brown pubescent. Inflorescences terminal, mostly pyramid-shaped thyrse, densely dusty brownish-yellow pubescent, 4.0-7.5 cm long; peduncles 1.5-2.5 cm long; bracts ovate-lanceolate to lanceolate-linear, 0.6-1.2 cm long, easily deciduous; bracteoles linear or lanceolate-linear, 1.0-2.5 mm long; pedicels 0.5-1.5 mm long. Calyx campanulate, 2.5-3.0 mm long, slightly 2-lipped with five equal lobes, apex acute, outside minutely brownish pubescent with brown glands; fruiting calyx distinctly 2-lipped with one lip 2-lobed and another 3-lobed, apex obtuse to subrounded. Corolla green to greenish yellow, 2-lipped, 4.5-5.5 mm long; tube 2.5-3.0 mm long, outside glabrous, inside densely white villose around throat; upper lip 1-lobed, entire, broadly oblong-obovate, obovate, concave, apex subrounded, outside glabrous or slightly pubescent; lower lip 3-lobed, middle lobe rounded to obovate, lateral lobes broadly oblong-ovate or ovate. Stamens 4, didynamous, filaments greenish-white, glabrous, slightly exserted; anther white. Ovary obovoid, 1.0-1.5 mm long, minutely pubescent and golden glandular near the apex; style white, slender, 3.5-4.5 mm long. Fruits drupaceous, purplish dark brown, obovoid to obovoid-ellipsoid, 7.0-8.0 × 4.5-5.5 mm, sparsely dusty pubescent and glandular.

Phenology.

Flower buds were observed in early April. Flowering was observedfrom mid-May to early June and fruiting from late May to late June.

Distribution.

Per the introduction record, P. bhamoensis is originally collected from northeastern Myanmar, but currently known only from the cultivated type in the Xishuangbanna Tropical Botanical Garden (Figure 4 ). Based on our experience in examination of Asian Premna specimens, we suspect that the species is probably endemic to Kachin State of Myanmar and distributed in a very small area.

Etymology.

The specific epithet of this new species, " bhamoensis ", is derived from the name of the locality, Bhamo County, from where the species was originally collected.

Preliminary conservation status.

Since we have neither rediscovered the wild population of P. bhamoensis in Myanmar, nor identified any other specimens in the herbarium, very few details about its natural distribution and/or population status are currently known. Therefore, the information is inadequate to assess the species’ risk of extinction, whether directly or indirectly. In accordance with the IUCN Red List Categories ( IUCN 2012), we propose to temporarily list the species as a taxon under the Data Deficient (DD) category. Further field surveys in northeastern Myanmar are needed to gain more information on its abundance and/or distribution.

Other specimen examined.

MYANMAR. Kachin State, Bhamo County, voucher from a cultivated plant at the Xishuangbanna Tropical Botanical Garden, Menglun Town, Mengla County, Yunnan Province, Alt. 550 m, 21.404408N, 101.152401E, 31 May 2012, Y. H. Tan 120 [flowering branches] (XTBG!).

Note.

Among the seven Premna species recorded in the flora of Kachin State, Myanmar ( Kress et al. 2003), P. pyramidata (= P. tomentosa Willd.) and P. bengalensis have dense stellate hairs on branchlets, leaves, and petioles, P. racemosa (= P. interrupta Wall. ex Schauer) has spikelike inflorescences, and P. scandens is a large and glabrous vine. Thus, these four species are quite distinct from P. bhamoensis . P. barbata and P. khasiana both have bracts at the base of branchlets, whereas such bracts are absent in P. bhamoensis . P. pinguis differs from P. bhamoensis in having ovate leaves with strongly serrulate margins, and branches without interpetiolar ridges. All these differences make P. bhamoensis a distinct Premna species in Myanmar. A key to the Premna species in Kachin State of Myanmar is provided below.

Among the Asian Premna , P. menglaensis , as the introduction label indicated, is the species showing the maximum level of similarity to P. bhamoensis . Both are climbing Woody shrubs with ovate-oblong to elliptic leaves, and congested pyramid-shaped inflorescences. However, P. bhamoensis can be easily distinguished from P. menglaensis on the basis of the differences observed in a number of traits, e.g., branchlets and petioles (densely pubescent vs. glabrous or glabrescent), leaf blades (papery and minutely pubescent vs. leathery and glabrous), flower color (green to greenish yellow vs. red), calyx shape (slightly 2-lipped with five equal lobes vs. distinctly 2-lipped with entire or minute emarginate lips), stamens length (exserted from corolla vs. included) (Figure 2 ). P. bhamoensis also resembles P. fulva Craib in having a climbing habit, dense indumentum on branchlets and petioles, green to greenish yellow flowers, and calyces with five lobes, but clearly differs in leaf shape (ovate-oblong to elliptic with entire margins vs. ovate to subrounded with serrate margins) and inflorescence type (congested pyramid-shaped thyrse vs. flat-topped corymbose cyme) ( Chen and Gilbert 1994, Tan and Li 2016). Besides, branchlets, petioles, leaf blades, and inflorescences of P. fulva are densely covered with long, spreading, golden-brown hairs, which are different from the hairs found on P. bhamoensis .

Figures

Figure 1. Premna bhamoensis Y. T. Tan & B. Li, sp. nov. A habit B a branchlet with ovate-oblong to elliptic leaves C branchlet and petioles covered by dense brownish pubescences D abaxial surface of leaf blade.

Figure 2. Morphological comparison between Premna bhamoensis (A-C) and P. menglaensis (a-c). A, a branchlets with inflorescences B, b inflorescences, flowers and calyces (in the blank circle) C, c fruitescences and fruits (arrow show fruiting calyx).

Figure 3. Line drawing of Premna bhamoensis Y. T. Tan & B. Li, sp. nov. A abranchlets with inflorescence B inflorescence C fruitescence D corolla E calyx in flowering (left) and fruiting (right) F fruit.

Figure 4. Distribution map of Premna bhamoensis (green circle showing the type locality and red circle for the cultivated cite) and P. menglaensis (orange star).