Justicia thailandica Y.F.Deng & Y.Tong, 2019

Tong, Yi & Deng, Yunfei, 2019, Justicia thailandica, a new species of Acanthaceae from Thailand, PhytoKeys 124, pp. 11-22 : 12-15

Justicia thailandica Y.F.Deng & Y.Tong sp. nov. Figures 1 , 2

Type.

THAILAND. Kanchanaburi Province, Kanchanaburi District, Huay Bankau, 14°55'00"N, 98°45'00"E, mixed deciduous forest on limestone, 900 m alt., 13 Nov 1971, C. F. van Beusekom, C. Phengklai, R. Geesink & B. Wongwan 3759 (holotype: MO2366671!; isotypes: BKF!, C!, K!, L!, P!).

Diagnosis.

The new species is similar to Justicia quadrifaria (Nees) T. Anderson, but differs on account of the whole plant being white villous (not pubescent), leaf blade ovate (not oval, oblong to rarely ovate) with margin usually entire (not slightly undulate), apex shortly caudate or acute (not acuminate), base cuneate (not decurrent), petiole 8-12 mm (not 5-7 mm) long, calyx densely white villous (not pubescent), inflorescence bracts spathulate and villous (not ovate to obovate and sparsely pubescent) and capsule longer than the calyx (not shorter than the calyx). It is also similar to J. championii , but differs by the whole plant being white villous (not pubescent), and inflorescence bracts spathulate and villous (not obovate-spatulate with apex emarginate and sparsely pubescent).

Perennial herbs, 20-35 cm tall. Stems cylindrical or sometimes quadrangular, base decumbent and usually rooting at nodes then erect, densely white villous. Leaves opposite; petiole 0.8-1.2 cm long, villous; blades ovate, oval to sometimes lanceolate, 3.5-7.5 × 1.5-4 cm, papery, apex shortly caudate or acute, margin usually entire or slightly undulate, base cuneate to shortly attenuate, both surfaces densely white villous, mid-vein and secondary veins prominent on both surfaces, secondary veins (5 or) 6 on each side of mid-vein, covered with grayish white strip-like cystoliths. Spikes axillary, ca. 1 cm, usually several flowers in a cluster. Inflorescence bracts leaf-like, usually spathulate, rarely obovate, 7-8.5 × 4-5 mm, with a petiole 3-5 mm long, villous, pinnately veined with white strip-like cystoliths, apex round or sometimes obtuse, base decurrent onto petiole. Bracts and bracteoles linear, 1-1.2 mm long, white villous relatively sparsely below the middle. Calyx 7-9 mm, 5-lobed almost to base; lobes linear-lanceolate with conspicuous membranous margins, white villous, especially above the middle, apex acuminate. Corolla ca. 9 mm long, outside white villous, tube and upper lip white, lower lip white with purple spots; tube slightly longer than limb; upper lip triangular, minutely 2-lobed; lower lip 3-lobed, lobes imbricate, suborbicular. Stamens 2, attached to corolla tube, exserted; filaments ca. 2.2 cm long, basally villous; anther bithecous, thecae superposed, upper one smaller and muticous, lower one larger and with a white spur at base, anther connective pubescent. Ovary glabrous, green, fusiform with nectary flower disc bowl-shaped at base; style ca. 5 mm long, sparsely villous at base, stigma slightly 2-lobed. Capsule fusiform, 6-7 mm, glabrous, sometimes pilose at the tip. Seeds 4, compressed, ca. 1.1 × 1 mm, somewhat heart-shaped or obovate, brown or yellowish-brown, testa tuberculate.

Etymology.

The specific epithet “thailandica” is derived from Thailand, where the new species is found.

Phenology.

The new species was recorded in flowering from August to November and fruiting from October to December.

Distribution and habitat.

Justicia thailandica is only known from Thailand (Fig. 4 ). It grows in the thickets on the limestone hills or evergreen forest at elevations of 400-900 m.

Conservation status.

Currently, Justicia thailandica is only known from seven locations of Thailand with eight collections and the estimated extent of occurrence more than 20000 km2. We speculate that it may be widespread in Thailand, but is likely to qualify for a threatened category in the near future due to its vulnerable karst habitat and human activities leading to a decline in such habitats. It is therefore assessed as "Near threatened" (NE) according to the IUCN Red List categories and criteria ( IUCN 2017).

Additional specimens examined.

THAILAND. Chiang Mai: Chiang Dao District, Doi Chiang Dao, SE foothills near Ban Yang Pong Luang, 575 m alt., 30 Sep 1989, J. F. Maxwell 89-1169 (A, CAS, L). Kanchanaburi: Thong Pha Phum District, Krieng Kwia, 420 m alt., 27 Nov 1982, H. Koyama, H. Terao & T. Wongprasert 30402 (BKF, C, K). Khon Kaen: Phu Khieo Game Reserve, ca. 80 km east of Phetchabun, 16°50'00"N, 101°58'00"E, 850 m alt., 8 Nov 1984, G. Murata, C. Phengklai, S. Mitsuta, T. Yahara, H. Nagumasu & N. Nantasan T-41809 (A, BKF, TI). Loei: Nam Nao National Park, 101°23'00"-28'00"N, 16°48'00"-49'00"E, near check point of road to National Park, 280-350 m alt., 28 Oct 1984, Gen Murata, C. Phengklai, S. Mitsuta, T. Yaahara, G. Nagamasu & N. Nantasan T-51534 (TI); Pha Som Dej-Phataalern, Phu Luang NP., 1000 m alt., 14 Oct 2000, M. Norsaengsri 1075 (QBG). Nakhon Ratchasima: Pak Thong Chai District, Salika Forest, 40 km SE from Pak Thong Chai, 14°40'00"N, 102°2'00"E, 400 m alt., 25 Oct 1971, C. F. van Beusekom, Chan Wid & amp; R. Geesink 3362 (BKF, C, K, L, MO, P). Phetchabun: Nam Nao District, Nam Nao National Park, 25 Dec 1982, H. Koyama, H. Terao & T. Wongprasert T-31662 (BKF); Nam Nao, 24 Aug 2006, P. Chantaranothai et al. s.n. (BKF, QBG); Loam Gow District, Nahaw Now, 900 m alt., 17 Nov 1973, J. F. ± 614 (AAU).

Pollen and seed morphology

Pollen grains of Justicia thailandica are 2-colporate, bilaterally symmetrical, elliptic in both polar and equatorial view, polar axis [P]=33.0 ± 1.55 μm, equatorial diameter [E]=21.6 ± 0.85 μm, P/E=1.52 ± 0.06, aperture area with 2 rows of 6-7 unequal-sized insulae, ornamentation of the insulae microreticulate with few scattered granules between muri (Fig. 3 : A-B).

Seeds of Justicia thailandica are compressed, somewhat heart-shaped or obovate, brown or yellowish-brown, 1.1-1.2 × 1-1.1 mm, testa densely tuberculate with conspicuous rounded or oblong tubercles, ornamentation of tubercles irregular polygonal (Fig. 3 : C-D).

Figures

Figure 1. Justicia thailandica A habit B magnifying the portion of leaf blades showing the tomentum C adaxil surface of inflorescence bract D abaxil surface of inflorescence bract E bract F bracteoles G calyx H corolla I dorsal view of the anther J frontal view of the anthers K pistil with nectary disc L, M opened capsule N capsule with calyx O seed. (Drawn by Cui Dinghan from the holotype van Beusekom et al. 3759).

Figure 2. Justicia thailandica A adaxial surface of inflorescence bract B abaxial surface of inflorescence bract C bract D bracteoles E stigma F pistil with nectary disc G calyx H dorsal view of anther I frontal view of anther J opened capsule K outside of capsule L inside of capsule showing retinacula M seed.

Figure 3. Pollen and seed morphology of Justicia thailandica under SEM A pollen grain in equatorial view B exine ornamentation of pollen grain C seed D seed testa.

Figure 4. Distribution map of Justicia thailandica (black circle).