Impatiens piufanensis Hook. f. var. villosa G.W. Hu, S.X. Ding & S. Peng, 2022

Ding, Shi-Xiong, Liu, Hui-Hua, Wang, Ben-Zhong, Peng, Shuai, Jiang, Hui, Mutie, Fredrick Munyao, Waswa, Emmanuel Nyongesa & Hu, Guang-Wan, 2022, Impatiens piufanensis var. villosa (Balsaminaceae), a new variety from Hubei and Hunan, China, Phytotaxa 560 (2), pp. 241-246 : 243-245

Impatiens piufanensis Hook. f. var. villosa G.W. Hu, S.X. Ding & S. Peng , var. nov. ( Figure 1 )

Type. CHINA. Hubei, Enshi Tujia and Miao Autonomous Prefecture, Xianfeng county , Pingbaying township , Jingzhuquan village , elev. 764 m, 30 Jun 2021, S.X. Ding, H. Jiang, F.M. Mutie, E.N. Waswa PBY-399 (holotype: HIB!, isotypes: HIB!, PE!) .

Diagnosis. This new variety can be distinguished from the nominate variety by its stem, leaves, lateral sepals, lower sepal, and the midvein of upper petal covered by dense white villus and puberulent peduncles and pedicels.

Description. Plants perennial, with many orange-yellow tuberous roots. Stem succulent, erect, 20−50 cm tall, whole plant densely white villous; base usually procumbent, branched in upper part, white villous, densely so above; nodes on lower part of stem swollen to tuberiform, densely white pubescent. Leaves alternate, crowded on upper part of stem, petiole short, 0.3−2 cm long; leaf blade ovate or ovate-lanceolate, 6−20 × 3−9 cm, base cuneate, apex acuminate, margin coarsely serrate, teeth mucronulate; lateral veins 8−12 pairs, sparsely tiny spinose on veins, petiole and blade white villous on both surfaces, trichomes denser on veins. Inflorescences racemose, 1−3 flowered, axillary in upper leaves, peduncles longer than petioles, slender, 3.5−5.5 cm long; pedicels 4−5 cm long, bracteate at base, bracts narrowly long lanceolate, ca. 1 cm long; peduncles and pedicels sparsely white villous. Flowers red, ca. 3.5 cm long. Lateral sepals 2, lanceolate, ca. 0.7 mm long, apex long rostellate, abaxially white villous. Lower sepal funnelform, ca. 2.5 cm deep, sparsely or densely white villous and with red striae on both surfaces, narrowed into an inner-curved and slender spur ca. as long as limb at base. Upper petal suborbicular, apex middle concave, 1−1.5 cm in diameter, adaxially red striate; abaxial midvein thickened, densely white villous, carinate, apex curved, mucronulate, lateral united petals 2-lobed with red striae, not clawed, 2−2.5 cm long, basal lobes orbicular, apex obtuse, distal lobes dolabriform, apex rounded. Anthers acute. Ovary erect, 5-carpellate, fusiform, glabrous. Capsule linear, striate, 1−2 cm long, glabrous, pedicels puberulent. Seeds brown, subglobose, ca. 3 mm in diameter, smooth. Fl. Jun−Sep, fr. Jul−Oct.

Paratypes. CHINA. Hunan, Xiangxi Tujia and Miao Autonomous Prefecture, Baojing county , Lüdong Mountain , elev. 1000 m, 31 Aug 2021, H.H. Liu HGW-001494 (HIB!)

Distribution and habitat. The new variety is currently known only from Wulingshan Region in Southwestern Hubei and Northwestern Hunan, where I. piufanensis var. piufanensis is also distributed ( Figure 2 ). It grows in moist roadside ditches on the forest margins in mountains at elevations of 700–1000 m.

Etymology. The varietal epithet “ villosa ” refers to the long soft hairs on the stem, leaves, peduncles, pedicels, lateral sepals, lower sepal and the midvein of upper petal of the new variety. The Chinese name is “ 多ffi块节凤仙 ″ ”.

Phylogenetic analysis. Total genomic DNA of two samples of the new variety and one sample of the nominate variety I. piufanensis were extracted from the dried leaves with Mag-MK Plant Genomic DNA extraction kits (Sangon Biotech, Shanghai) ( Janssens et al. 2006). In total, 27 ITS (internal transcribed spacer) DNA sequences (25 taxa) were used to construct a maximum likelihood (ML) phylogenetic tree. Of these, 24 sequences of Impatiens sect. Impatiens species were downloaded from GenBank. The phylogenetic relationship shows that the samples of the new variety and the nominate variety are clustered into a monophyletic clade with strong support. However, neither the two samples of I. piufanensis var. villosa nor the two samples of nominate variety are clustered into a monophyletic clade ( Figure 3 ).

Discussion. The phylogenetic analyses support the samples of I. piufanensis var. villosa and I. piufanensis var. piufanensis belong to a species. Morphologically, I. piufanensis var. villosa highly resembles I. piufanensis var. piufanensis in key characters, such as nodes on lower part of stem swollen to tuberiform, funnelform limb of lower sepal ca. as long as spur and lower sepal, upper petal and lateral united petals with red striae. The main difference between the new variety and the nominate variety is the indumentum on several organs like the stems, leaves, peduncles, pedicels, sepals and the midvein of upper petals. Thus, we treat those newly found hairy plants of I. piufanensis as a different variety.

According to our field observations, some characters have a broader range of variation than that in the protologue of I. piufanensis ( Hooker et al. 1908) , such as inflorescences (1–3 flowered vs 1-flowered in the protologue), leaf blade size (3−15 × 1.5−5 cm vs 3−6 × 1.5−2.5 cm in the protologue) and number of lateral veins (4−10 pairs vs 4−5 pairs in the protologue). These variations are shown in Figure 4 (based on Hu et al. HGW-001231, deposited at HIB).

The natural distribution center of I. piufanensis var. piufanensis is Wulingshan Region at elevations of 900–2000 m according to the collection records in China and related literature ( Chen et al. 2007, Yu 2012), while the new variety is distributed at a lower elevation from 700 m to 1000 m in the same area. Thus, habitat heterogeneity caused by different elevations likely resulted in the variation of I. piufanensis and hence the formation of the new variety.

Figures

FIGURE 1. Impatiens piufanensis var. villosa A habitat B root C root and basal part of stem, showing node D fruiting branch, adaxial view E fruiting branch, abaxial view F−I flowers J flowers, top view and side view K dissection of a flower L infructescence. (Scale bars: A−E: 4 cm; J−L: 2 cm.)

FIGURE 2. Distribution of Impatiens piufanensis. The different colours represent the collection density of I. piufanensis var. piufanensis in different provinces. Black dots represent the two populations of I. piufanensis var. villosa.

FIGURE 3. Maximum likelihood (ML) phylogenetic tree based on nuclear ITS DNA sequences of Impatiens sect.Impatiens. The samples of I. piufanensis var. villosa and I. piufanensis-2 are highlighted in red, and bootstrap values are shown at each branch node. The vouchers of I. piufanensis var. villosa-1, I. piufanensis var. villosa-2 and I. piufanensis-2 are Ding et al. PBY-399, Liu HGW-001494 and Hu et al. HGW-001231, respectively, all deposited in HIB.

FIGURE 4. Impatiens piufanensis var. piufanensis A habitat B−D inflorescences E−G flower’s detailed morphology H inflorescence with two young fruits and one flower I dissection of a flower. (Scale bars: G−I: 2 cm.)