Coleus hairulii Kiew, 2021

Kiew, Ruth & Kamin, Imin, 2021, Coleus (Lamiaceae) in Peninsular Malaysia including two new species, PhytoKeys 186, pp. 93-110 : 93

1. Coleus hairulii Kiew sp. nov.

Diagnosis.

Most similar to Coleus paniculatus Benth. (as Plectranthus glabratus (Benth.) Alston in Suddee et al. 2004) from southern Thailand in its habit (both are low, little branched or unbranched herbs), in their inflorescences with conspicuous side branches and cymules with more than 3 flowers, but Coleus hairulii (Figure 2 ) is different (Table 1 ) in its short branches from the inflorescence axis 2.5-4 cm long, i.e. 3-5 times shorter than the inflorescence length (vs. branches from the inflorescence axis 5.5-10 cm long and 2-3 times shorter than the inflorescence), and its calyx 6-7 mm long in fruit (vs. 4-6 mm long).

Type.

Malaysia. Peninsular Malaysia: Kedah, Baling District, Gunung Pulai, Kepala Gajah , trail to summit 5°40.05'N, 100°53.03'E, 19 Nov 2019, Wan Syafiq & R. Kiew FRI 99402 (holotype KEP!; isotypes K!, SAN!, SAR!, SING!) .

Description.

Soft unbranched herb, 15-30(-40) cm tall, erect becoming decumbent, not aromatic, stem quadrangular, ca. 2 mm thick, fleshy, glabrous. Leaves glabrous; petiole slender, 2-6.5 cm long, decreasing in length in the upper leaves; lamina thinly membranous, ovate to broadly ovate, 5-6 × 3.3-4.5 cm, base rounded to truncate, margin shallowly crenate, apex acute to acuminate, pale green beneath; veins 4-5 on either side of midrib. Inflorescence thyrsoid, terminal, erect, 13-18 cm long, shortly glandular pubescent, rachis and branches pale reddish, peduncle 7-9.5 cm long, 3-4 tiers of short side branches from the inflorescence axis, 2.5-4 cm long; cymes single-flowered; bracts sessile, foliose, lanceolate, apex acute, 6-7 × 2-3 mm; pedicels attached slightly above centre of calyx, 2.5-4 mm long at anthesis, 4-5 mm in fruit. Flower pendent; calyx obliquely campanulate, reddish brown, posterior lip rosy red, 2-3 mm long at anthesis, 10-veined, unequally 5-lobed, minutely puberulent, in fruit 6-7 mm long, 2.5-3 mm wide, posterior lip spathulate, apex subacute, 2-2.5 × 3 mm, anterior lip with 2 lateral and lower lobes sharply acute, slightly upcurved, lateral lobes ca. 2-2.5 mm long, slightly longer than the lower 2.5 mm; corolla (9-)20 mm long, minutely puberulent outside, pale or bluish purple except for the white posterior lip, tube sigmoid, basal ca. 3 mm very narrow ca. 1 mm wide, abruptly decurved and dilating to 3-4 mm wide across the mouth, posterior lip erect, ca. 8 × 6 mm, almost rounded with a broad median lobe deeply notched at apex, lateral lobes narrow, slightly longer than the median lobe, anterior lip boat-shaped and enclosing the stamens and style, 9-14 mm long, 5-6 mm deep and wide with a dense tuft of long translucent hairs in the inner lower half; stamens hardly exserted, only anther tips visible, in 2 pairs, filaments 7 and 8 mm long, anthers slightly obovoid, ca. 0. 5 mm long; stigma slightly bilobed, slightly exserted from tip of lower corolla lip. Nutlets orbicular in outline, bilaterally flattened, ca. 1 mm long; testa reddish brown, smooth.

Distribution.

Endemic in Peninsular Malaysia, Kedah, Gunung Pulai, known only from two populations (trail to Gunung Pulai and Kampung Sungai Limau) at a single locality (Map 1 ).

Provisional conservation status.

Critically Endangered B1ab(i,iii,iv). The species is known only from one locality, with a low population size, estimated at less than a hundred individuals. The hill is threatened by a proposal for a cement quarry. (Assessed by A.R. Rafidah).

Ecology.

Restricted to a limestone karst hill at ca. 90-155 m on lower slopes of the hill, growing in soil-filled cracks in the limestone rocks on or near wet, shaded vertical cliffs or between deep pinnacles on a low summit, locally common in a restricted area. It is not known if it is short-lived or an annual plant.

Etymology.

Named for Mohd. Hairul b. Mohd. Amin (b. 1984), field staff in the KEP Herbarium, Forest Research Institute Malaysia, who first collected this species (Figure 1 ).

Additional specimen examined.

Peninsular Malaysia, Kedah: Baling Hill, Kampung Sungai Limau, 5°40.38'N, 100°53.23'E, 17 Nov 2011, Mohd. Hairul et al. FRI 54055 (K!, KEP!, SING!).

Note.

In discussions with AJ Paton (pers. comm.), he pointed out that the type of Plectranthus glabratus (Benth.) Alston (now C. paniculatus ) from Chennai (Madras) is a more robust plant with a thicker stem, bigger leaves and relatively shorter branches of the inflorescence compared with the three specimens from southern Thailand. Coleus hairulii resembles specimens from southern Thailand that are also all from limestone rocks ( Suddee et al. 2004).

Figures

Map 1. Distribution of Coleus hairulii (circle), C. kunstleri (triangle) and C. rafidahiae (star) in Peninsular Malaysia.

Figure 1. Coleus hairulii Kiew, sp. nov. A Mohd. Hairul bin Mohd. Amin with a flowering specimen B habit and limestone habitat C inflorescence and flower enlarged. (Photographs: A by AR Ummul-Nazrah B by Wan Mohamad Syafiq bin Wan Putra and C by AR Rafidah).

Figure 2. Coleus hairulii Kiew A flowering plant B flower side view C flower side view with corolla cut away to show stamens D flower side view to show hirsute patch on anterior lip E calyx in flower F calyx opened G stamen apex H ovary side view I glandular hairs of the pedicel J calyx in fruit K seed. (All from FRI 94402. Drawn by N. Mohamad Aidil).