Justiciathailandica, a new species of Acanthaceae from Thailand.

Yi Tong,Yunfei Deng

doi:10.3897/phytokeys.124.33745

Abstract

A new species of Justicia (Acanthaceae), J.thailandica, is described and illustrated from Thailand. The new species belongs to Justiciasect.Harnieria and is similar to J.quadrifaria and J.championii, but differs on account of the obviously densely white indumentum in the inflorescence bracts and calyx, ovate leaf blades with margin usually entire, spathulate inflorescence bracts and length ratio of calyx to mature capsule. It is assessed to be “Near threatened” (NE) according to IUCN Red List Category and Criteria. Pollen and seed morphology characters are also reported. Species of Justiciasect.Harnieria in Thailand are discussed and a key to the three recognized species is presented.

Highlights

Justicia L. is the largest genus in the family Acanthaceae and consists of about 600 species distributed in tropical and temperate regions of the world (Graham 1988; Hu et al 2011; Mabberley 2017)
Pollen grains and seeds were taken from dried specimens (Beusekom et al 3759, MO2366671) and mounted on aluminium stubs coated with gold in a sputter coater after being cleaned in water using ultrasound, and examined using scanning electron microcopy (SEM; JSM-6360LV)
Characters of pollen grains and seed testa have proved valuable in sectional delimitation in the genus Justicia (Graham 1988)

Summary

Introduction

Justicia L. is the largest genus in the family Acanthaceae and consists of about 600 species distributed in tropical and temperate (to a lesser extent) regions of the world (Graham 1988; Hu et al 2011; Mabberley 2017) Is characterized by the abbreviated axillary spikes, leaf-like inflorescence bracts, fusiform capsules and tuberculate seeds (Tong et al 2016) It comprises approximately 76 species distributed in the tropical and subtropical regions of Africa and Asia with two species extending to Australia (Barker 1986; Hedrén 1989; Tong et al 2016). Anderson appear to represent an undescribed species, which differs from the latter two species by the characters of indumentum, leaves, petiole, calyx, inflorescence bracts and length ratio of calyx to mature capsule

Materials and methods

Discussion