Aspidistra ronganensis C. R. Lin, J. Liu & W. B. Xu, 2016

Aspidistra ronganensis C. R. Lin, J. Liu & W. B. Xu View in CoL , sp. nov. ( Figs. 1 View FIGURE 1 , 2A–F View FIGURE 2 )

Type:— CHINA. Guangxi Zhuang Autonomous Region, Rongan County, Dongqi Township, limestone mountains, alt. 338 m a.s.l., 5 September 2014, Wei-Bin Xu 12005 (holotype IBK! , isotype IBK! ).

Herbs perennial, evergreen, rhizomatous. Rhizome creeping, subterete, 8–10 mm in diameter, densely covered with nodes, roots numerous. Sheathing leaves 6–8, purplish red, 2–12 cm long, enveloping base of petiole, fibrous when withered. Leaves solitary, 2–3 cm apart; petiole stiff upright, 20–48 cm long, 2–3 mm thick, sulcate adaxially; leaf blade oblong lanceolate, 30–45 cm long, 6.5–10 cm wide, green, inequilateral, apex acuminate, base cuneate, gradually tapered to petiole, margin entire. Peduncle erect or declining, 0.5–2 cm long, with 5–6 pale bracts, bracts gradually wider from base to top of peduncle, upper most ones at base of perigone broadly ovate, 8–10 mm long, 14–16 mm wide, apex acuminate. Flowers solitary, perigone tubular, fleshy, 20–25 mm long, 8-lobed apically; tube 18–20 mm long, 6–8 mm in diam., white; lobes unequal in shape, triangular-lanceolate, 4–5 mm long and 2–3 mm wide at base, pale purplish-red, apex gradually acuminate and usually slightly outcurved, with spurlike basal protuberances. Stamens 8, inserted on upper mid part of perigone tube, positioned much higher than stigma, anthers pale yellow, lineate, ca. 5 mm long, 0. 5– 1 mm wide. Pistil narrow obconical, white, 5–6 mm long, stigma slightly enlarged, 2–3 mm in diam., slightly concave and pale red adaxially, shallowly 4-lobed at margin, lobes unequal. Flowering from September to October.

Distribution and ecology:— Aspidistra ronganensis is currently known only from the type locality in Rongan County, northern Guangxi, China. It grows on shaded rocky limestone slopes in broad-leaved forests, together with species like Cephalotaxus hainanensis Li , Pteroceltis tatarinowii Maxim, Handeliodendron bodinieri (Levl.) Rehd., Bennettiodendron leprosipes (Clos) Merr. , Gomphandra tetrandra (Wall. in Roxb.) Sleum., Pilea sp. , Lecanthus sp. , and Cyrtomium fortune J. Sm.

Taxonomic relationships:— Aspidistra ronganensis is similar to A. retusa K.Y.Lang & S.Z.Huang in Lang (1981: 379, Figs. 2G–I View FIGURE 2 ) in the shape of the flower, but differs by the perigone tubular (vs. campanulate), 20–25 × 6–8 mm, lobes triangular-lanceolate (vs. deltoid-ovate), apex gradually acuminate (vs. subobtuse), with spur-like basal protuberances (vs. without keels), anthers lineate, ca. 5 × 0. 5– 1 mm (vs. ovate, 1.8 × 1.8 mm). Aspidistra ronganensis is also similar to A. australis S.Z.He & W.F.Xu in He et al. (2013: 305), however, the latter species differs in its flower shorter, perigone tube 8–10× 3.3–3.6 mm, stamens inserted slightly below middle of perigone tube lower than stigma. On the contrary, stamens are conspicuously higher than stigma in A. ronganensis , a rare feature in Aspidistra .

Additional specimen studied (paratype):— CHINA. Guangxi Zhuang Autonomous Region, Guilin City, Yanshan Township, introduced by Wei-Bin Xu from the type locality, cultivated, 27 September 2014, Chun-rui Lin 1047 ( IBK!) .

Karyology:—The chromosome number of Aspidistra ronganensis was determined to be 2n = 38 ( Fig. 3 View FIGURE 3 ), with the karyotype formula of 2n = 38 = 24m + 2sm + 12st + 1B ( Fig. 3B View FIGURE 3 ). A single B chromosome is marked by an arrowhead in Fig. 3A View FIGURE 3 ; No. 39 in Fig. 3B View FIGURE 3 . Among the 38 chromosomes, the first pair has median (m) centromeres and is longer than the remaining pairs; chromosomes from the pairs II to VIII gradually vary and have their centromeres at the subterminal (st) position, except the pair III which has submedian (sm) centromeres; the remaining chromosomes are smaller and have median (m) centromeres ( Fig. 3B View FIGURE 3 ). Secondary constrictions are observed on both smaller median chromosomes (arrows in Fig. 3A View FIGURE 3 ; Nos. 17 and 18 in Fig. 3B View FIGURE 3 ). Upon five individual karyotypes, the average length of chromosome complement is 4.22 μm, and the karyotype asymmetry indices CV CL and M CA are 63.24 and 26.20, respectively. Cytological data of 49 species in the genus Aspidistra have been reported by now ( Bogner & Arnautov 2004, Li 2004, Yamashita & Tamura 2004, Qiao et al. 2008, Hou et al. 2009, Lin et al. 2010, Liu et al. 2011, Lin et al. 2013, He et al. 2013, Meng et al. 2014). All Aspidistra species share a basic chromosome number of x = 18 or 19 ( Li 2004, Gao et al. 2015), and Aspidistra ronganensis is no exception. It is worth noting that a single B chromosome has been observed in Aspidistra ronganensis , which has an average length of 1.45 μm, and is smaller than all the other chromosomes. B chromosomes were reported only in some species of Aspidistra in literature. For example, two B chromosomes have been reported from Aspidistra fimbriata Wang & Lang (1978: 76) and different number of B chromosomes were found in different cells of Aspidistra tonkinensis Wang & Lang (1978: 77) ( Huang et al. 1997). The origin and evolution of the B chromosomes in Aspidistra deserve further studies.