Wednesday, February 17, 2021

[Botany • 2020] Involucrella lithophila (Rubiaceae: Spermacoceae) • A New Species from Guangxi, China

Involucrella lithophila M.D.Yuan & R.J.Wang,

in Yuan & Wang, 2020.

Involucrella lithophila from the limestone area of Guangxi, China, is described and illustrated here. It is most similar to Hedyotis kurzii and Involucrella chereevensis in having tetragonal stems, slender pedicels and loculicidally dehiscent capsules, but it differs from the former by its 3–5 (–7)-lobed stipules, heterostylous and white flowers and depressed seeds, and from the latter by its 2–4 secondary leaf veins and heterostylous flowers. The molecular phylogenetic analysis revealed that this new species was embedded in the Involucrella clade and closely related to I. chereevensis. It is evaluated as Least Concern according to IUCN Red List Categories and Criteria.

Keywords: Hedyotis-Oldenlandia complex, palynology, Phylogenetic analysis, seed morphology, taxonomy, Eudicots

Involucrella lithophila M.D.Yuan & R.J.Wang.
A: Habit; B: Inflorescence; C: Tetragonal stem and its transverse section; D: Stipule; E: Leaf blade; F & G: Short-styled flower; H: Long-styled flower; I: Young capsule; J: Dehisced capsule; K: Seeds.
(A & B: from Rui-Jiang Wang 2596; C: from Guo-Bin Jiang et al. 1491; D-G & I–K: from Sheng Chen YS49; H: from Rui-Jiang Wang 2597). 

Involucrella lithophila M.D.Yuan & R.J.Wang, sp. nov. 

Diagnosis:— Involucrella lithophila is similar to Hedyotis kurzii and Involucrella chereevensis and in their tetragonal stem, slender pedicels and cymose to paniculate inflorescences, but it differs from Hedyotis kurzii in its glabrous stipules, heterostylous and white flowers, turbinate or hemispherical capsule, and depressed seeds. It also distinguishes from Involucrella chereevensis in its smaller leaves, 2–4 secondary veins at each side, 3–5 (–7)-lobed stipules, and heterostylous flowers (Table 2).  

Etymology:— The specific epithet refers to the habitat of this species, which usually grows on the cliffs or gaps of limestone rocks.

 Ming-Deng Yuan and Rui-Jiang Wang. 2020. Involucrella lithophila (Rubiaceae: Spermacoceae): A New Species from Guangxi, China. Phytotaxa. 464(1); 59–68. DOI:  10.11646/phytotaxa.464.1.4