The genus Pedicularis L. is the one of the most species-rich genera in the family Orobanchaceae, with approximately 680 species (POWO, 2025) worldwide. It is primarily distributed in the temperate to frigid zones of the Northern Hemisphere, and the Hengduan Mountains and Qinghai-Tibet Plateau in China constitute its distribution center, where over 386 species have been recorded (Tsoong, 1963; Yang et al., 2003; Yu et al., 2010, 2015a, 2015b, 2018). Owing to the complex morphological variation of Pedicularis species and their susceptibility to phenotypic differentiation induced by environmental factors, there have been numerous cases of synonymy in historical taxonomic treatments. This has posed challenges to species identification and research on the genus’ resources (Li, 1948, 1949; Tsoong, 1955, 1956a, 1956b, 1961).

Pedicularis brevilabris Franch. was described based on the collection collected by J. A. Soulié (Specimen No. 208) from northwestern Sichuan Province (Franchet, 1900). Its original description emphasized the characteristic that “the lower lip is distinctly shorter than the galea, with an ovate middle lobe.” In contrast, P. sima Maxim. was named and published by Maxim. (1881), based on Specimen No. 541 collected by Przewalski from western Gansu Province. The type specimen of P. sima records the features: “the lower lip is ciliate and shorter than the galea, with a rounded middle lobe.” For a long time, these two taxa have been recognized as distinct species, primarily due to differences in the “length of the lower lip.”

In recent field surveys conducted in Gansu, Qinghai, Sichuan, and other regions, a large number of Pedicularis individuals were found to have lower lips measuring 3–7 mm in length. Their other morphological characteristics, including leaf shape, inflorescence arrangement, and calyx features, were highly consistent with the original type descriptions of P. brevilabris and P. sima. Meanwhile, a re-examination of type specimens and related specimens deposited in the herbaria of the Institute of Botany, Chinese Academy of Sciences (PE), the Northwest Institute of Plateau Biology, Chinese Academy of Sciences (HNWP), and the Dendrology Herbarium of Gansu Agricultural University (GAUF) revealed that the “length of the lower lip” is not a stable diagnostic character. Based on these findings, this study uses multi-dimensional evidence to demonstrate the synonymy between P. brevilabris and P. sima.

In this study, specimens or high-resolution images of Pedicularis (including the type specimens of P. brevilabris and P. sima) deposited in the herbaria PE, KUN, LZU, HNWP, GAUF, K, and LE were examined in detail. Additionally, in-situ observations were conducted on living individuals of these two Pedicularis taxa, with one population sampled from the type locality of P. sima—namely Gannan Tibetan Autonomous Prefecture, Gansu Province. Morphological observations focused on leaves, flowers, and fruits, with particular attention paid to corolla morphology, the sizes of the galea and lower lip, and the size of calyx teeth.

The corolla lower lip length of the P. brevilabris type specimen ranged from 3.2–4.1 mm, while that of the P. sima type specimen was 5.3–6.8 mm. However, in specimens collected from the overlapping distribution area of the two taxa (Gannan Tibetan Autonomous Prefecture, Gansu Province, and Yushu Tibetan Autonomous Prefecture, Qinghai Province), the lower lip length showed continuous variation 3.0–7.2 mm. This rules out the possibility of using morphological discontinuity as a basis for species delimitation.

The type specimen of P. brevilabris (Soulié, J. A. 208), collected in 1893, exhibited obvious compression deformation of the corolla lower lip during specimen pressing (Fig. 1), and the flowers were at the early opening stage with the lower lip not yet fully expanded. In contrast, the type specimen of P. sima (Przewalski 541) was collected at the full flowering stage (Fig. 2), with well-preserved floral organs. The specimen contains a detailed description of floral anatomy (Fig. 2D, E). A comparison of field photos of living individuals of the two taxa at the same flowering stage (Fig. 3), and diagnostic morphological characters (Table 1), that the lower lip length of individuals at the early flowering stage was generally shorter than that at the full flowering stage. Furthermore, external force compression during specimen pressing could further shorten the apparent length of the lower lip. Additional specimens examined findings (Appendix 1.) indicate that the “short lower lip” characteristic of P. brevilabris is likely an artifact caused by the combination of individual developmental stage and specimen processing, rather than a stable heritable trait.

The type locality of P. brevilabris (northwestern Sichuan Province) is located at the edge of the core distribution area of P. sima (western Gansu Province). The two taxa form a continuous distribution zone in areas such as Gannan (Gansu Province) and Aba (Sichuan Province), with no obvious geographical isolation. Both grow in alpine meadows and at the edges of thickets at an altitude of 3,200–4,500 m, with highly consistent habitat conditions. This further supports the conclusion that there is no niche differentiation between the two.

According to Article 11 of the International Code of Nomenclature for algae, fungi, and plants (Editorial Committee of the Madrid Code, 2025), when a species is proven to be the same taxon as another previously published species, the earlier-published name shall be treated as the correct name, and the later-published name becomes a synonym. Pedicularis sima was published in 1881, while P. brevilabris was published in 1900. Since the publication date of P. sima is earlier than that of P. brevilabris, and there are no special circumstances for retaining the later name with priority, P. sima should be the correct name. Treating P. brevilabris as its synonym is consistent with the ICN provisions.

Pedicularis sima Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg 27: 514, 1881 (Fig. 3).—TYPE: CHINA. Gansu province, Western, 1880, N. M. Przewalski 541 (holotype: LE01034781!; isotype: PE00033024!).

Pedicularis brevilabris Franch. syn. nov., Bull. Soc. Bot. France 47: 33, 1900.—TYPE: CHINA. Sichuan province, Dajianlu, 1893, J.-A. Soulié 208 (lectotype!; isolectotypes with the numbers 226! and 236!).

Herbs, annual, 25–50 cm tall, not blackening when dried, with a slender root. Stem branched at the base or simple, bearing 4 lines of woolly hairs. Leaves lower ones opposite, upper ones in whorls of 3 and 4, densely curly-hairy on both surfaces; petioles up to 15 mm long; blades oblong, pinnately deeply lobed, with 5–7 pairs of lobes, lobes ovate to oblong and serrate margins. Inflorescence spicate or capitate, with 3 flowers per whorl; the lower whorls are lax and densely covered with long hairs; calyx short-cylindrical, 7–8 mm long, with 5 irregular teeth; the posterior calyx teeth smaller than others, triangular, entire; the other calyx teeth enlarged, serrate, often revolute; abaxial veins are densely long-hairy; corolla rose-colored or pale fuchsia; collora tube nearly straight, shorter than both calyx tube and galea; galea is slightly falcate-curved, with a rounded forehead, abruptly narrows apically into a short but distinct beak; lower lip ciliate, 6–8 mm long, 6–9 mm wide, slightly shorter than galea; middle lobe rhombic, smaller than lateral lobes; stamens glabrous. Fruits capsules, triangular-lanceolate. Seeds elongate ovoid.

Phenology: Flowering period: July–August; Fruiting period: August.

Distribution and habitat: Qinghai, Sichuan, eastern Tibet; in Gansu Province: Diebu, Zhuoni, Hezuo, Xiahe, Yongdeng (Liancheng), Tianzhu. Grows in alpine meadows or alpine thickets, at an altitude of 3,000–3,800 m.