Whytockia W.W.Sm.

Whytockia W.W.Sm. View in CoL ,

Trans. Bot. Soc. Edinburgh 27: 338. 1919.

Type: Whytockia chiritiflora (Oliv.) W.W.Sm.

Perennial herbs. Stem base decumbent or creeping, rooting from the nodes, flowering stem ascending or erect; rarely branched or branching from the creeping part (from the axils of fallen leaves). Leaves strongly anisophyllous, thinly membranous, pubescent, with scattered, sessile chalk glands on the underside, sessile or the large-leaves with a short petiole, ovate, strongly unequal at base, apex acute, margins obscurely serrate. Cymes unilateral (pair-flowered cincinni) emerging from the axils of the large leaves, ebracteolate. Sepals free or connate at base, aestivation descending-imbricate, slightly striate (by the presence of secretory canals), chalk glands on inner sides. Corolla white or pink to light violet-purple, short tubular to infundibuliform, limb bilabiate, lobes rounded. Stamens 4, didynamous, inserted at corolla base; filaments hairy in the upper part; anthers coherent, thecae divaricate. Ovary globose or subglobose, glabrous, bilocular throughout or for the most part, placentation axile; style strongly set off from ovary; stigma capitate or bilobed. Capsule globose or subglobose, 2-valved or opening irregularly.

Brief taxonomic history of Whytockia

Whytockia is one of the seven genera of Gesneriaceae subfam. Didymocarpoideae tribe Epithemateae . Its closest ally is the unifoliate genus Monophyllaea R.Br. ( Weber, 1976), both forming the subtribe Monophyllaeinae within tribe Epithemateae ( Weber et al., 2013) . Whytockia was established by W.W. Smith (1919, honouring James Whytock, 1845-1926, then president of the Botanical Society of Edinburgh during the years 1917-1920) for a species originally described in Stauranthera Benth. , S. chiritiflora Oliv. Concomitantly, Smith (1919) also described a new variety of this species ( S. chiritiflora var. minor W.W.Sm. ). More than 20 years later, Burtt (1941) transferred a species of Rhychoglossum Blume (from Taiwan) to Whytockia ( W. sasakii (Hayata) B.L.Burtt ). More than 40 years later, another species of Stauranthera was transferred to Whytockia : W. tsiangiana (Hand.-Mazz.) A.Weber ( Weber 1982, with recognition of three varieties). More recently, and essentially by the work of Wang (1995, 2003) and Wang and Li (1997, 2000), the species number was raised to eight and one variety ( GRC, 2022), either by description of new species ( W. bijiensis Yin Z.Wang & Z.Yu Li , W. gongshanensis , W. hekouensis Yin Z.Wang , W. purpurascens Yin Z.Wang ), or raising a variety to species rank ( W. wilsonii (A.Weber) Yin Z.Wang ).

The nature of the species of Whytockia

Most of the species of Whytockia are known only from a single locality. The specific differences are rather slight. Only one species, W. tsiangiana , has a wide distribution, covering South and Central China (from Yunnan to Hunan provinces; Wang et al., 1998). This is followed by the close ally W. sasakii , known from the north-eastern part of Taiwan. The remaining species are known only from a single locality, with the newly collected Indian material having the furthest western distribution. Very little is known about the variability of W. tsiangiana across its distribution area, and a critical study of Whytockia , based on recollections and molecular data, is badly needed. Despite this shortcoming, we below critically compare the Indian material with its congeners, in particular with its morphologically closest, W. tsiangiana and W. sasakii , to establish its new species status.