﻿Hemilophiacardiocarpa (Brassicaceae), a new species from Yunnan, southwest China

﻿Abstract Hemilophiacardiocarpa (Brassicaceae), the sixth species of the Chinese endemic genus Hemilophia, is described and illustrated. This plant is found in the Jiaozishan Mountains in Dongchuan District, northern Yunnan, southwest China. Morphologically, it shows close relationships with H.rockii and H.pulchella, but differs from it in the leaf shape and size, inflorescence, flower size, shape of fruit and length of its pedicel. An updated key to the taxa of Hemilophia is provided.


Introduction
Hemilophia Franch. is a small genus established by the French botanist Adrien René Franchet based on Delavay's specimens from Lijiang, southwest China (Franchet 1889 (Zhou et al. 2001). All are restricted to high-elevation habitats of the Hengduan Mountains in southwest China (Zhou et al. 2001;Al-Shehbaz 2015). The systematic position of Hemilophia in Brassicaceae is not well resolved up to now. Schulz (1936) placed it in the tribe Lepidieae DC., whereas this treatment was not supported by recent studies (Al-Shehbaz 2012;Nikolov et al. 2019;Walden et al. 2020;Francis et al. 2021;Liu et al. 2021).
During our botanical fieldwork to Jiaozishan Mountains in southwest China in August 2018, a showy plant of Hemilophia with cordiform fruits was collected. By thoroughly examining the specimens of this genus housed at herbaria KUN, PE and YUKU, and a survey of digital images available at the database Plant Photo Bank of China (http://ppbc.iplant.cn/), we found that this plant had been collected or photographed several times in Jiaozishan Mountains and was wrongly identified as H. rockii O. E. Schulz. Comparison with related species demonstrates that this plant actually represents a distinct species hitherto not described.

Taxonomy
Phenology. Flowering occurs from May to early September, and fruiting from August to October.
Etymology. The specific epithet cardiocarpa is derived from the Greek words "kardio" (heart) and "karpos" (fruit), referring to the fruit shape of this new species. Vernacular name. Chinese Mandarin: xin guo ban ji ji (心果半脊荠). Distribution and ecology. Hemilophia cardiocarpa appears to be a rare species endemic to the Jiaozishan Mountains, which are located in the northern Yunnan  Taxonomic notes. The presence of cordiform fruits is the most remarkable character to distinguish Hemilophia cardiocarpa from other species of this genus. Morphologically, H. cardiocarpa is most similar to H. rockii (Fig. 4) in having a similar habit and sharing similar indumentum, leaf shape, as well as flower size and arrangement. Nevertheless, it clearly differs from the latter by its cauline leaves usually ovate, rarely obovate or oblong (vs. oblanceolate to narrowly elliptic, or rarely ovate in H. rockii), 5-8 mm (vs. 3-4 (6)) long, 2-4 mm (vs. 1-1.5 (3)) wide, racemes usually 5-13 (vs. 5-6) -flowered, pedicels of fruits shorter than or nearly equal to its leaflike bract (vs. significantly longer than leaflike bract) and fruit cordate (vs. spindle or narrowly oblong) in shape. H. cardiocarpa is also similar to the type species of the genus, H. pulchella Franch., from which it is readily distinguished by the racemes usually 5-13-flowered (vs. 2-3-flowered in H. pulchella), and petals bluishwhite to white (vs. pink), 4-7 mm (vs. 2.5-3.5 mm) long, 2-3.5 mm (vs. 1.5-2 mm) wide. Taxa of Hemilophia can be distinguished through the morphological characters presented in the following identification key modified from Al-Shehbaz (2002, 2015.
Identification key to the species of Hemilophia