Typhonium jinpingense, a New Species from Yunnan, China, with the Lowest Diploid Chromosome Number in Araceae Wang Zhonglang, Li Heng and Bian Fuhua Kunming Institute of Botany, Academia Sinica, Kunming 650204, Yunnan, China ABSTRACT. Typhonium jinpingense Z. L. Wang, H. MATERIALS AND METHODS Li & F. H. Bian (Araceae) from Yunnan, China, is described as a new species in Araceae. The kar- The plants were collected in the ®eld from Jinp- yotype of metaphase chromosomes in somatic cells ing, Yunnan, China, and cultivated in the Kunming Botanical Garden for the taxonomic and cytological is: 2n 5 10 5 2m12st16sm. This is the lowest study. diploid number so far reported in this family. For the taxonomic study, we ®rst checked the Key words: Araceae, chromosome numbers, Ty- characteristics carefully, using the key for Typhon- phonium. ium developed by Sriboonma et al. (1994) to de- termine which section the species belongs to. We then compared it to all described Typhonium spe- cies, including the species published subsequent to Fieldwork was conducted in the southeast part the 1994 revision. of Yunnan Province, China, in October 1999. The For the cytological study, growing root-tips were new species was found on a slope near a small pre-treated in 0.002 mol/L 8-hydroxyquinoline at stream with an elevation from 1000 to 1550 m in room temperature for 3 hours, then ®xed in Clarke Jinping County, Yunnan Province, China. This (ethanol/acetic acid, 3:1) solution at 48C for 30 plant was ®rst collected and identi®ed as Typhon- minutes. They were then hydrolyzed in 1 mol/L hy- ium blumei Nicolson & Sivadasan, as the leaves drochloric acid at 608C for 3±4 minutes. After be- were quite similar to this species. The plants were ing rinsed in distilled water 3 times, the root tips subsequently grown and propagated; so far, more were dyed in Carbol Fuchsin solution for 1 hour, than 20 individuals are cultivated in the Kunming then squashed and sealed. Photos were taken using Botanical Garden. From April to August 2000 four the method described in Li and Zhang (1991). The of them ¯owered, displaying quite different char- chromosomes were classi®ed by arm ratio accord- acteristics from T. blumei. After checking the chro- ing to Leven and Fredga (1964). The karyotype mosome number for several individuals, we found classi®cation followed the criteria developed by the lowest diploid chromosome number in Araceae Stebbins (1971). reported to date. We checked the morphological characteristics carefully and compared them to all RESULTS the species in the genus Typhonium, and realized this taxon is an undescribed species. CYTOLOGICAL STUDY According to the revision of Typhonium (Sri- The chromosome number was counted in more boonma et al., 1994) and our recent investigations, than 15 somatic cells, and the karyotype analysis 16 species and 4 varieties in the genus have been was carried out in 1 good cell. The karyotype of found in China thus far, belonging to 5 sections. the new species is described in Table 1 and illus- Recently, Hetterscheid and Boyce (2000) merged trated in Figure 2. The chromosome number in so- the genus Sauromatum Schott (all 3 species found matic cells is 10, and the karyotypical formula is in China) with Typhonium Schott (Wang & Li, 2n 5 2x 5 10 5 2m12st16sm. This species is a 1999). Thus the number of Typhonium species in diploid. The length in somatic mitotic cells ranges China is now thought to be 19. However, based on from 2.9 mm to 6.1 mm, while the relative length species richness in neighboring countries (Hetter- of the chromosomes ranges from 6.5 to 13.2. The scheid et al., 2001; Hetterscheid & Nguyen, 2001), ratio of the longest chromosome (No. 1) to the short- this is likely to be an underestimate of the actual est one (No. 10) is 2.04. The percentage with Long number of Typhonium species in China, especially Arm/Short Arm .2:1 is 80%. The karyotypical in the southern part of Yunnan Province. asymmetry belongs to the 3B type. NOVON 12: 286±289. 2002. Volume 12, Number 2 Wang et al. 287 2002 Typhonium jinpingense from Yunnan Table 1. The parameters of somatic chromosomes in Discussion. Typhonium is commonly accepted mitotic metaphase of Typhonium jinpingense. as comprising ®ve sections as described by Sri- boonma et al. (1994). This new species belongs to Pair TL AR PC section Typhonium. From the shape of the leaf 1 13.3 2.0 sm blade, this new species is easily differentiated from 2 12.7 2.6 sm the other Chinese Typhonium species, except T. 3 10.1 2.4 sm blumei. It is distinguished from T. blumei in having 4 7.7 3.3 st the spathe tube pale green, dark purple at the top 5 6.6 1.4 m (not entirely dark purple), the blade narrowly lan- Note: TL 5 Total relative length; AR 5 arm ratio; PC ceolate (not broadly ovate), dark purple, spreading 5 position of centromere. and arching, apex long acuminate but not twisted, clavate sterile rudiments, erect, and in its chro- mosome number, 2n 5 10. TAXONOMIC DESCRIPTION Based on recent comprehensive reviews of the Typhonium jinpingense Z. L. Wang, H. Li & F. cytology of the Araceae (Grayum, 1990; Mayo et H. Bian, sp. nov. TYPE: China. Yunnan Prov- al., 1997; Petersen, 1989, 1994), the chromosome ince: Jinping Xian, Shuangjin Bridge, road numbers vary greatly between and also within gen- side by stream, 1200 m, 30 Oct. 1999, F. H. era, from 2n 5 14 (Ulearum)to2n 5 168 (Arisae- Bian & R. Li 200 (holotype, KUN). [Cultivated ma). The lowest diploid number so far known in in Kunming Botanical Garden, 2n 5 10.] Fig- Araceae is 2n 5 14, observed in Ulearum sagit- ure 1. tatum Engler; based on our results, Typhonium jin- pingense (2n 5 10) has the lowest chromosome Haec species Typhonio blumei af®nis, sed spathae tubo number known to occur in the family. The chro- ovato, 1.5 cm longo, 5 mm diam., pallide viridi inferne, mosomes were easy to group into ®ve pairs (Fig. 2), atropurpureo superne, lamina angusta, lanceolata, 11 cm longa, medio 1 cm lata, basi atropurpurea, cretacea supra so Typhonium jinpingense is a diploid species and basin, ¯orum sterilium rudimentis clavatis, chromosoma- the basic chromosome number is 5. Other species tibus 2n 5 10 differt. of Typhonium have chromosome numbers of: 2n 5 16, 18, 20, 26, 36, 52, 54, 65, .100 (Mayo at al., Perennial herb, seasonally dormant, rhizome tu- 1997), making it one of the most variable genera berous, irregularly cylindrical, brown, horizontal or in this regard in Araceae. erect, producing small gemmules and many ®liform Primary basic chromosome number is a main roots, 2±2.5 cm long, 0.7±1.0 cm diam. Leaves 1± area of research in cytological studies. The discov- 3, petiole smooth, green, 10±17 cm long, 0.1 cm ery of the lowest diploid number in this study may diam., sheathing below ca. 1.5±2 cm long; blade spur further investigation of this aspect. Possibly chartaceous, green, cordate, usually cordate-hastate the following questions will be proposed: Was it or deeply cordate at base, 5±8 3 4±10 cm. Pedun- caused by extreme aneuploid reductions? Or is 2n cle about 1 cm long. Spathe: tube ovoid, pale green, 5 10 some kind of ``ancestral number'' only kept dark purple at the top, 1.5 cm long, 0.5 cm diam.; in Typhonium? We think the former is more likely. the blade narrowly lanceolate, chalky-white but It is well known that very low chromosome numbers dark purple at base, 11 cm long, 1 cm wide below (as well as very high ones) are more common in the middle, spreading and slightly arching, the advanced genera than in basal ones. Petersen apex long-acuminate but not twisted. Spadix ca. 14 (1994) postulated that very low chromosome num- cm long, pistillate portion ca. 0.5 cm long, green- bers were explained as aneuploid reductions, from ish, the style short, stigma dark purple, sterile por- an ancestral number x 5 12 or 14. Other authors tion ca. 0.4 cm long, densely covered proximally, proposed that there was an ``original'' series with x erect, yellowish, clavate rudiments, with naked in- 5 5, 6, 7, 8, and 9, and that all arose from 7 as terstice to 2 cm long; staminate portion to 0.5 cm they speculated the primary basic number as 7 long, densely congested, yellow; terminal appendix (Jones, 1957; Larsen, 1969; Marchant, 1973). As cylindrical, erect, purple, ca. 10 cm long, 2 mm stated by Mayo et al. (1997), reduction in diploid diam., sessile and not swollen at base, with very number occurs in various morphologically ad- strong odor. Flowering from the end of April to Au- vanced genera. We agreed with this opinion: Ty- gust. phonium is a much advanced genus in Araceae; Distribution. Known only from Jinping County, such a low chromosome number was possibly re- southeastern Yunnan, China, in wet ®elds and road- duced from a higher one. Other evidence came from sides by streams, altitude 1000±1550 m. our recent cytological studies in 9 Typhonium spe- 288 Novon Figure 1. Typhonium jinpingense Z. L. Wang, H. Li & F. H. Bian. Ð1. Plant with rhizome. Ð2. Rhizome. Ð3. Spathe. Ð4. Spadix. Ð5. Male portion. Ð6. Male ¯ower. Volume 12, Number 2 Wang et al. 289 2002 Typhonium jinpingense from Yunnan Figure 2. Cytological plates of Typhonium jinpingense. Ð1. Mitotic metaphase chromosomes in somatic cell. Ð2. Karyotype. Ð3. Idiogram. cies.