Isodon gongshanensis Y. P. Chen & C. L. Xiang, 2024

Chen, Ya-Ping, Peng, Hua, Paton, Alan J. & Xiang, Chun-Lei, 2024, Three new species of Isodon (Nepetoideae, Lamiaceae) from China, PhytoKeys 246, pp. 283-293 : 283-293

Isodon gongshanensis Y. P. Chen & C. L. Xiang sp. nov.

Fig. 3

Type.

China – Yunnan Prov. • Gongshan County, Dulongjiang Town ; alt. 2915 m; 27 ° 50 ' 33.93 ″ N, 98 ° 27 ' 27.85 ″ E; at the streamside in forests; 15 Aug 2020; Y. P. Chen et al. EM 1570 (holotype: KUN 1628216 !; isotypes: K!, KUN 1628214 !, PE!) .

Diagnosis.

Isodon gongshanensis is morphologically similar to I. rosthornii , but differs by having lanceolate (vs. triangular) and longer (ca. 1 mm vs. ca. 0.5 mm long) teeth of the posterior calyx lip, longer (6–7 mm vs. ca. 5 mm long) corollas with a pink (vs. white) posterior lip, but without spots (vs. with reddish-purple spots) and an ovary without glands (vs. with glands).

Herbs perennial, 50–150 cm tall. Stems erect, branched, quadrangular, 4 - sulcate, often claret, subglabrous to densely strigose. Leaves decussate; lamina ovate to broadly ovate, papery, 5–12 × 3–7 cm, apex acuminate, base cuneate to broadly cuneate, margin crenulate, adaxially green, sparsely strigose and glandular, abaxially light green, subglabrous, densely glandular; lateral veins 3–4 - paired; petioles 1–5 cm long, claret or green, strigose. Thyrses terminal and axillary, 10–20 cm long; cymes 3–7 - flowered, peduncles 1–2 mm long, pedicels 3–5 mm long, strigose; bracts ovate to broadly ovate, 2–30 mm long, apex lanceolate, margin crenulate or entire, petioles 0–5 mm long, bracteoles linear, ca. 1 mm long. Calyx campanulate, ca. 2.5 mm long, strigose and glandular outside; 2 - lipped to 1 / 2 its length, teeth narrowly triangular, apex acuminate, fruiting calyx dilated to ca. 5 mm long, posterior lip strongly reflexed. Corolla white, 6–7 mm long, declinate, strigose and glandular outside; tube 2.5–3 mm long, white, saccate abaxially near base, 1.5–2 mm in diameter; apex 2 - lipped, posterior lip pink, 4 - lobed, ca. 4 × 4 mm, reflexed, lobes subrounded, anterior lip entire, subrounded, concave, navicular, straight, 3.5–4 mm in diameter. Stamens 4, included; anther cells 2, confluent, divergent; filaments pubescent at base. Style included, glabrous, apex slightly subequally 2 - lobed. Ovaries glabrous. Mericarps not seen.

Phenology.

Flowering from July to September, fruiting from August to October.

Distribution and habitat.

Isodon gongshanensis is only known from Gongshan County in Yunnan Province, southwest China (Fig. 1 ). The new species usually grows in mixed needle-leaf and broadleaf forests at altitudes of 2700–2900 m.

Etymology.

The specific epithet is derived from the type locality of the new species, i. e. Gongshan County in Yunnan Province, China.

Chinese name (assigned here).

gòng shān xiāng chá cài (贡山香茶菜).

Additional specimens examined.

China – Yunnan Prov. • Gongshan County, Cikai Town, Danzhu Village ; alt. 2787 m; 27 ° 37 ' 17.14 ″ N, 98 ° 38 ' 1.04 ″ E; 25 Sep 2022; Y. J. Zhao et al. 22 ZYJ 023 ( KUN) ; • Gongshan County, Dulongjiang Town, near the Dulongjiang Tunnel ; 2 Jul 2015; Y. P. Chen & R. L. Stubbs EM 203 ( KUN!) ; • ibid.; 16 Oct 2019; L. Q. Jiang & Y. Y. Li LJ 28 ( KUN!) .

Figures

Figure 1. Geographic distribution of Isodon attenuatus (red triangle), I. gongshanensis (green circles) and I. sukungii (purple squares).

Figure 3. Morphology of Isodon gongshanensis from the type locality A habitat B habit C – E inflorescences F infructescence G leaves H corollas (Photographed by Ya-Ping Chen).