Gaultheria sect. Brossaea ser. Leucothoides

Fritsch, Peter W., Armstrong, Kate E., Aung, Mu Mu, Fujikawa, Kazumi & Lu, Lu, 2023, Gaultheria (Ericaceae) of Myanmar: an updated species list for the country, a new species, and a new species combination, Phytotaxa 595 (1), pp. 37-61 : 43-45

Classification — Gaultheria sect. Brossaea ser. Leucothoides .

Phylogenetic placement — Leucothoides s.l. clade.

Images — Figure 1 .

Illustration — Figure 2 .

Phenology —flowering April.

1

Habitat, elevation range, and distribution —Primary forest, Tsuga ( Endlicher 1847: 83) Carrière (1855: 185) forest margins, 2,386 – 2,800 m elevation. China (Xizang: Zayü; Myanmar (Kachin: Putao District).

Myanmar specimen — Kachin: Putao District. Hponganrazi Wildlife Sanctuary, between Hponyinrazi camp 1 and camp 2, 2,386 m, 27°36’47.1”N, 96°58’55.1”E, 30 April 2018 (fl), K. Armstrong et al. 4036 (ASM!, BRIT BRIT541063!, E!, NY 04290478!, RAF!) .

Notes — Gaultheria griffithiana var. insignis was described by R.C. Fang (1999) on the basis of a single collection from Zayü County, Xizang Province, China and stated by Fang to differ from the nominate variety by lanuginose rachises (versus pubescent), tomentose pedicels (versus pubescent), densely sericeous bracts and calyx interiors (versus subglabrous), and subcordate bases of the leaf blades (versus obtuse-rounded). In addition to these characters (although described slightly differently above), we find that it also differs by narrowly 3-winged stems (versus at most angulate), petioles 2–3 mm long (versus 4–12 mm), leaf blade secondary veins 9 to 12 on each side of midvein (versus 3 to 6), proximal secondary veins arcuate, distal secondary veins straight (versus not notably differentiated), leaf blade marginal teeth 73–93 per side (versus 40–75 per side), overwintering buds ovoid (versus linear), bracteoles 2.8–3.2 mm long (versus 1.5–2.0 mm long), and calyx lobes 3.0–3.9 × 1.9–2.4 mm (versus 1.5–2.8 × 1.3–1.8 mm), inside glabrous (versus white-tomentose at least apically). We consider these differences to align more with recognition at the species level and accordingly raise var. insignis to the rank of species.

Although Gaultheria insignis was originally described as a variety of G. griffithiana , in the key to Gaultheria in the Flora of China ( Fang & Stevens 2005) the taxon perhaps keys best to G. brevistipes by the key characters 1b, inflorescence racemose or corymbose, 10b, leaf blade more than 4 cm, 17a, twigs glabrous, 18a, leaf blade base rounded to auriculate-cordate, 19b, inflorescences racemose and secondary veins more than 3 pairs, and 20a, leaf blade auriculate-cordate at base, twigs trigonous and winged and rachis and pedicels pubescent. However, G. insignis is easily distinguished from G. brevistipes by the leaf blade marginal teeth with terminal setae borne at the notch formed by the serration and margin (versus at or toward the apex of the tooth); the leaf blade base shallowly cordate, with the basal sinus sharply angled and basal lobes not or just reaching the attachment point of the petiole to the stem or slightly below (versus base deeply cordate, with the basal sinus rounded and lobes extending well below the attachment point of the petiole to the stem); inflorescences placed below the leaves (versus usually above); peduncle and rachis villous (versus puberulous); bracts persistent (apparently—the fruits in the type material are immature) and sericeous-villous to -hirsute (versus caducous and glabrous); calyx lobes smooth (versus shrivelled; floral characters from Panda 2005); corolla globose or slightly depressed-globose (versus narrowly campanulate); and filaments glabrous (versus pilose).

Two specimens, i.e., CHINA. Xizang. [Motuo Xian,] Medog County, Hanmi Village, 2300–2400 m, 3 August 2007 (fr.), L. Lu 07404 (CAS 684674!), and South Tibet /Arunachal Pradesh: [Mechuka, Shi Yomi district], Pachakshiri District, Nyug La, 8,500 ft, 28°45’N, 94°00’E, 11 May 1938 (fl.), F. Ludlow et al. 3737 (E E00197191!) were identified by Lu and Fritsch, respectively, as Gaultheria griffithiana var. insignis . However, in both of these specimens the leaf bases are rounded or only slightly cordate, the inflorescence rachises are puberulent instead of lanate, the bracts and bracteoles are glabrous instead of lanate, and the calyx lobes are ovate-deltoid instead of lanceolate-deltoid. On this basis, we tentatively exclude these specimens from G. insignis . Whether they represent a variant of G. insignis or some other species, a hybrid, or an undescribed taxon requires further study beyond the scope of the current treatment.

A lectotype was selected because the KUN specimen cited as the holotype in the protologue and recorded as barcode 482924 in the Chinese Virtual Herbarium (www.cvh.ac.cn; but without image) is missing. Of the two specimens of the Qinhai-Xizang Complex Expedition 73-781 collection at PE, PE 00198242 was selected as lectotype because it has more leaves and inflorescences than PE 00198241.

Figures

FIGURE 1. Gaultheria insignis. A. Flowering branchlet. B. Leaf, abaxial view, and inflorescence. C. Leaf, adaxial view. D. Inflorescence. K. Armstrong et al. 4036. Photographs by KEA.

FIGURE 2. Gaultheria insignis. A. Flowering branchlet. B. Portion of leaf showing abaxial surface and margin. C. Inflorescence. D. Pedicel, bracteoles, and flower. E. Stamen, ventral view. F. Stamen, dorsal view. G. Dentate nectar disk and gynoecium. Based on K. Armstrong et al. 4036 (BRIT). Illustration by Samantha Peters.