龙南后蕊苣苔(苦苣苔科)的种内形态变异与补充描述

Intraspecific morphological variation and supplementary description of Oreocharis burttii(Gesneriaceae)

关键词:  马铃苣苔属, 后蕊苣苔属, 龙南后蕊苣苔, 种内形态变异, 形态补充描述

Key words:  Oreocharis, Opithandra, Oreocharis burttii, intraspecific morphological variation, supplementary description of morphology

摘要:

后蕊苣苔属是人为主观建立的属,其界定的特征为具有2枚可育的后位雄蕊,后被并入马铃苣苔属。该研究在中国广东省韶关市青云山自然保护区发现1种与龙南后蕊苣苔 [Oreocharis burttii (W. T. Wang)Mich. Möller & A. Weber]相似的马铃苣苔属植物,但该植物具有数目不定的可育雄蕊,为明确这一特殊种群的分类地位,并评估其是否应与龙南后蕊苣苔视为同种,该文通过形态比较与系统发育分析,对该居群进行物种界定。结果表明:(1)性状与分子数据支持在青云山自然保护区发现的待鉴定物种为龙南后蕊苣苔。青云山自然保护区发现的马铃苣苔属植物在核心鉴别性状(包括叶和花)上与龙南后蕊苣苔高度吻合,同时在系统发育树上,其样本与两个龙南后蕊苣苔样本聚成一枝。(2)青云山自然保护区的龙南后蕊苣苔居群与原白在形态性状大小上存在差异; 该居群相较于原始文献描述,其叶柄更长(5.7～13.5 cm vs. 0.5～5.4 cm),叶片更宽(4.6～5.4 cm vs. 1.7～4.0 cm),花序梗更长(5～12 cm vs. 2～6 cm),花萼更大(ca. 5 mm × 2 mm vs. 3.5～3.8 mm × ca. 1 mm),花冠筒更大(ca. 15 mm × 7 mm vs. 10～14 mm × ca. 3.5 mm)。(3)青云山自然保护区的龙南后蕊苣苔居群与原白在花序分枝数量、花数量、可育雄蕊数量上存在差异; 其花序分枝回数通常更多(2～3 vs. 1～2),花数量通常更多(5～14 vs. 2～7),具有数目不定的可育雄蕊[在观察的20个个体中:1枚(5%,罕见); 2枚(70%); 3枚(12.5%); 4枚(12.5%)] vs. 2枚。综上,该研究对龙南后蕊苣苔的形态性状进行了补充描述。该研究结果拓宽了龙南后蕊苣苔的形态变异区间,有助于更加全面地认识龙南后蕊苣苔的种内形态变异,为其后续的物种精确鉴定与分类修订提供了基础资料。

Abstract:

Opithandra B. L. Burtt, an artificial genus established on the basis of a single morphological character, namely having two fertile posticous stamens, was merged into Oreocharis Benth. In this study, we observed a plant species(Oreocharis sp.)which is similar to Oreocharis burttii (W. T. Wang)Mich. Möller & A. Weber in the Qingyunshan Nature Reserve of Shaoguan, Guangdong, China, but it exhibits variable numbers of fertile stamens. To clarify the taxonomic identity of this unusual population and to evaluate whether it should be treated as conspecific with O. burttii, we performed species delimitation on this population using both morphological comparisons and phylogenetic analyses. The results are as follows:(1)Both morphological and molecular data support that the unidentified species discovered in Qingyunshan Nature Reserve is O. burttii. It is highly consistent with O. burttii in core diagnostic characters, including the morphological characteristics of leaves and flowers. On the phylogenetic tree, its sample clusters into one clade together with the two samples of O. burttii.(2)The population discovered in Qingyunshan Nature Reserve differs from the protologue in the sizes of several morphological traits. Compared to the original description, individuals in this population possess longer petioles(5.7-13.5 cm vs. 0.5-5.4 cm), wider leaf blades(4.6-5.4 cm vs. 1.7-4.0 cm), cymes with longer peduncles(5-12 cm vs. 2-6 cm), larger calyxes(ca. 5 mm × 2 mm vs. 3.5-3.8 mm × ca. 1 mm)and larger corolla tubes(ca. 15 mm × 7 mm vs. 10-14 mm × ca. 3.5 mm).(3)The population discovered in Qingyunshan Nature Reserve differs from the protologue in quantity of the cyme branch orders, number of flowers and number of fertile stamens. Specifically, it has more orders of cyme branches(2-3 vs. 1-2), more flowers(5-14 vs. 2-7), and a variable number of fertile stamens [in 20 individuals: 1(5%, rare); 2(70%); 3(12.5%); 4(12.5%)] vs. 2. In conclusion, this study provides a supplementary morphological description for O. burttii. These findings expand the known range of morphological variation for this species, contribute to a more comprehensive understanding of its intraspecific morphological variation, provide essential foundational data for future accurate identification and taxonomic revision.