Arisaema cordigerum Z.X.Ma, 2025

Ma, Zhengxu, 2025, Materia Revisionis Arisaemarum: III. taxonomic notes and five new taxa of the genus Arisaema (Araceae) from South China, Phytotaxa 697 (1), pp. 47-67 : 48-51

1.1. Arisaema cordigerum Z.X.Ma , sp. nov. ( Figs. 1–3 )

Arisaema cordigerum is allied with A. pachystachyum Hetterscheid & Gusman (2003: 37) but differs in having a strongly cordate white patch at the back of spathe, a spadix axis not distinctly swollen to the base, and a shortly recurving spadix-appendix, 3.5–5.6 cm long.

Type: — CHINA. Yunnan Province: Pu’er, Menglian County, along road G219, near Gongxincun, from Menglian to Jingxin, 12 June 2024, Y.E.Wang 784 (holotype BAZI!, isotype PE!).

Perennial geophyte, seasonally dormant, paradioecious. Subterranean stem tuberous, pale white, subglobose, to 4.5 cm in diam., bearing tubercles. Eophyll unknown. Cataphylls 3, membranous, free. Foliage leaves 1–2; petiole dull purplish green, mottled with dark purple, to 40.4 cm long, proximally sheathing into a upright pseudostem, petiolar sheath free; leaf blade trifoliolate, dull green, waxy, thickly membranous; laminae venation forming a smooth and clear brochidodromous collective venation close to the leaf margin, lateral veins raised at abaxial surface, strongly impressed at adaxial surface; lateral leaflets oblique oblong, 13.7–26.5 × 9.7–12.6 cm, base rounded, subsessile, apex acuminate and caudate, with a short tail 0.3–0.8 cm long; central leaflet elliptic to oblong, 15.7–30.7 × 11.1–17.1 cm, with petiolule 0.9–3.5 cm long. Inflorescence solitary, always below leaves; peduncle concolorous with petiole. Spathe tube green and mottled with dark dots on the abaxial surface, glossily pale green on the adaxial surface, cylindric, 5.2–5.5 cm long, 1.0– 1.3 cm in diam, with a long cordate white patch in the middle, ca. 1.9–3.5 × 1.6–2.3 cm; spathe mouth green, obliquely truncate, not auriculate; limb green, triangular–ovate, 1.7–2.0 cm wide (at base), long acuminate to the apex, with a short filiform tail. Spadix dioecious, 5.8–7.9 cm long; female zone subcylindric, 1.5–2.3 cm long, 0.4–0.7 cm in diam.; gynoecia densely arranged; ovary glossily green, obovoid; placentation basal; style short but obvious; stigma white, pubescent; male zone subcylindric, 1.3–1.5 cm long; androecia lax; synandrium consisting 2 bithecal anthers, cofiliment short; thecae dark purple, globose, dehiscing by a short slit resulting in an apical pore; connective inconspicuous; appendix purplish green, slender, 3.5–5.6 cm long, sessile at base, attenuate and curving forward at apex; neuters purplish green, subulate, curved, to 0.3 cm long, covering on proximal portion of female spadix; Infructescence and seed unknown. Anthesis form May to June.

Distribution: —Endemic to SW China (SW Yunnan, Pu’er), likely in E Myanmar.

Eponymy: —The Latin epithet “ cordigerum ” comes from “cordis” and “gerere”, meaning “bearing a heart” or “heart-bearing”, describing the diagnostic heart-shaped white patch on the back of the spathe.

Additional specimens examined (paratypes): — CHINA. Yunnan Province: Pu’er, Gongxin, Gongxincun , Xinzhai , Qiuyushan Hill , in forest valley, elev. ca. 1300 m, 11 May 2010, S.S.Zhou 7320 (HITBC [mounted on two sheets, sheet numbers: 138322, 138323]!) ; Jingxin, Jingxin Cun, on limestone hills along Nanlei River , elev. ca. 950 m, 20 May 2010, S.S.Zhou 7611 (HITBC [sheet number: 138617]!) ; Jingxin, Langdao , under the forest, elev. 1250 m, 5 June 2012, H.Dong, L.Chen & Q. Zhao 175 (KUN [barcode: KUN1227439 ]!) ; Simao, in forest west of Lake Heilongtang , 11 June 2024, Y.E.Wang 751 (BAZI!, PE!) .

2. Arisaema sect. Auriculata (Engl.) Z.X.Ma , stat. nov. Basionym:— Arisaema [infragen. unranked] Auriculata Engler (1920: 163, as “§ 4”). Type:— A. auriculatum Buchet (1911: 123) (Art. 10.8, Turland et al. 2018)

Small geophyte, paradioecious. Subterranean stem tuberous, globose, small, to 1.2 cm in diam. Phyllotaxy quincuncial. Cataphyll and petiolar sheath closed proximally; pseudostem subterranean, subtended completely by cataphyll. Foliage leaf pedate, leaflets entire or variously erose; leaf rachis present, rarely obscure. Spathe green or pale brown, densely flushed with dark purple or dark brown spots, auriculate at mouth. Spadix unisexual; androecia initiation subcentrifugal (not genuinely acropetal); synandrium consisting 2 bithecal anthers, cofiliment short, thecae globose, dehiscing by a short slit resulting in an apical pore; appendix terete or flagellate, swollen proximally and gradually narrowed to the base, often sessile, apex obtuse or filiform.

Species included: — Arisaema auriculatum Buchet [= A. lushuiense G.W.Hu & H.Li in Hu et al. (2012b: 684)] and A. meleagris Buchet (1911: 122) [= A. shimienense H.Li in Li et al. (1977: 108)].

Distribution: —Alpine regions in Central-Southwest China (Chongqing, Hubei, NW Hunan, S Shaanxi, Sichuan, NW Yunnan), elev. 1400–3100 m.

Notes: —The newly recognized Arisaema sect. Auriculata emerges from a revised classification of the species A. auriculatum Buchet and A. meleagris Buchet that previously being assigned to the A. sect. Nepenthoidea ( Gusman & Gusman 2002 pp. 221, 2006 p. 265, Li et al. 2010 p. 55, Murata 2011 p. 63). The section A. sect. Nepenthoidea was first proposed by Gusman & Gusman (2002 p. 221), based on the unranked infrageneric division of Engler (1920 p. 208). However, due to the lack of proper citation of basionym, this section was not validly published until Murata (2011 pp. 63). Arisaema nepenthoides , which automatically became the type, was the only species cited when the unranked group was established ( Engler 1920 p. 208), while A. wattii Hooker f. (1893: 498) was recognized as part of A. sect. Pistillata in the same publication ( Engler 1920 p. 199). The two species, A. nepenthoides and A. wattii , form a small coherent group, A. sect. Nepenthoidea sensu stricto, while phylogenetic analysis indicated ( Arunkumar et al. 2019), though holding a different interpretation here, a necessity of adopting a broader concept of the species A. nepenthoides to synonymize most of its satellite species, resulting a monotypic section.

Recently, well-sampled phylogenetic studies have shown A. sect. Nepenthoidea sensu lato being paraphyletic ( Ohi-Toma et al. 2016, Tran et al. 2022). Together with A. auriculatum-A. meleagris (A. sect. Auriculata) and A. sect. Decipientia ( Engler 1920: 195) H.Li (each a monophyletic group), A. sect. Nepenthoidea s.l. represents a paraphyletic group at the base of the Clade IX, and it is appropriate to accept A. sect. Auriculata as a separate section to maintain the monophyly of A. sect. Nepenthoidea s.l.

Additionally, the patterns of geographical distribution of A. sect. Auriculata and A. sect. Nepenthoidea s.s. highlights their distinct floristic associations. The distribution of A. sect. Nepenthoidea s.s. is largely eastern Himalayan, which begins from Nepal and extends through the entire eastern Himalayas ( Hara 1971, Li 1979a p. 177), northeastward to the northern end of the Gaoligong Mountains ( Li et al. 2000 pp. 1057, 1060–1062), and southward along the margin of Yunnan-Guizhou Plateau to the subalpine regions of southeastern Yunnan [ Li 1979b p. 821, as A. biauriculatum Smith ex Handel-Mazzetti (1936: 1365) ], southwestern Guangxi ( Qin & Fang 2003 p. 141), and northern Vietnam ( Luu et al. 2022, as A. vietnamense Luu, Q.B.Nguyen, H.C.Nguyen, & T.Q.T.Nguyen ), adjacent to the Gulf of Tonkin. In contrast, A. sect. Auriculata is endemic to the alpine regions of Central China-Hengduan Mountains ( Li et al. 2010 pp. 56, 60), where it consists of two species with nearly sympatric distribution that extends from the Wuling Mountains in central China across the Sichuan Basin to the Qinling Mountains in the north and high-altitude areas of the Hengduan Mountains in the west. The only known area where the distributions for these two sections overlap is Yunling-Gaoligong Mountains in northwestern Yunnan ( Li et al. 2000 pp. 1057, 1060–1062, Li 2003 pp. 613, 616), perhaps also in the alpine regions of the Kachin Mountains in Myanmar, which has yet been reported.

Consequently, based on their distinct distribution patterns and probable different geographical origins, I propose that A. sect. Auriculata and A. sect. Nepenthoidea s.s. represent different floristic associations: specifically A. sect. Nepenthoidea s.s. likely originated in the eastern Himalayas, with patchy distribution in the southeastern extension toward the Gulf of Tonkin possibly being a glacial relic, and, in contrast, A. sect. Auriculata likely originated in the Central China and East Hengduan Mountains, where it has continued to thrive.

3. Arisaema sect. Clavata ( Engler 1920: 171) H.Ohashi & J. Murata (1980: 283) Type:— A. clavatum Buchet (1911: 121)

Figures

FIGURE 1. Habit of Arisaema cordigerum. All photos are vouched by the holotype, Y.E. Wang 784 (BAZI!).

FIGURE 2. Leaf blade of Arisaema cordigerum. A.Abaxial surface with raised foliar venation; B. adaxial surface.All photos are vouched by the holotype, Y.E. Wang 784 (BAZI!).

FIGURE 3. Inflorescence of Arisaema cordigerum. A, B. Inflorescences in a bunch showing the pattern of variation, note the heart-shaped white patch at the back of the spathe; C. the heart-shaped white patch viewed from the adaxial spathe surface; D–F. inflorescence in different views; G. male spadix; H. female spadix; I. details on neuters of female spadix.All photos are vouched by the holotype, Y.E.Wang 784 (BAZI!).