Range extension of Christisonia scortechinii from mainland Southeast Asia into Borneo, and notes on the distinction between Aeginetia and Christisonia (Orobanchaceae)

K M Wong,Antony Van Der Ent

doi:10.1186/s40529-015-0109-3

Abstract

Background Christisonia is a little-documented and poorly studied root-parasitic genus in the Orobanchaceae occurring in India, China, Indochina and part of the Malesian region. Recent collection of a Christisonia taxon in Kinabalu Park in Sabah, Borneo, taxonomically identical to earlier Sabah collections that have hitherto not been recorded in the literature, led to an assessment of the taxonomic identity of the species against Christisonia scortechinii, C. siamensis, C. sinensis and related species.ResultsSome taxa in China, Indochina, the Malay Peninsula, and the Philippines are morphologically identical to the Borneo taxon except in the number of calyx lobes, but differ by several distinctive characters from other well-distinguished species in the region. Studies of dried herbarium specimens, augmented by photographic images of different stages of fresh flowering material and a scrutiny of available descriptions confirmed that the calyx has two primary lobes in the bud that may separate into 3–5 portions, giving a variable number of apparent lobes in specimen material collected at different localities. This new scrutiny of the calyx also permitted an improved description of the calyx differences that separate Christisonia and the closely related Aeginetia, which have not been clearly elucidated in the past.Conclusions Christisonia scortechinii Prain (Orobanchaceae), the only species that was described as having an initially spathaceous calyx among species of this root-parasitic genus, is newly recorded for Borneo (including Kinabalu Park, where its presence has been overlooked). The range of the species in mainland Southeast Asia, previously extended from Peninsular Malaysia to Thailand and Vietnam, is here further extended to Laos and China. Christisonia wightii Elmer (relevant to the Philippines) and C. sinensis Beck (China) are reduced to synonymy.

Highlights

Christisonia is a little-documented and poorly studied root-parasitic genus in the Orobanchaceae occurring in India, China, Indochina and part of the Malesian region
The root-parasitic genus Christisonia Gardn. has ca. 20 species distributed from India to China and the Malay Peninsula (Parnell 2001, 2008), Philippines, SW Celebes and Flores (Van Steenis 1967)
Christisonia newly recorded for Borneo Cedric E. Better known for his orchid collecting (Kiew 2003), was apparently the first person to collect a Christisonia from Mount Kinabalu and Borneo, this was never recorded in any publication, including the recently completed Plants of Mount Kinabalu where Beaman and Anderson (2004) had missed Carr’s number SFN 26457 of this taxon in the Singapore Herbarium

Summary

Introduction

Christisonia is a little-documented and poorly studied root-parasitic genus in the Orobanchaceae occurring in India, China, Indochina and part of the Malesian region. Most Christisonia spp. have largely white corollas, and most Aeginetia spp. lilac, purple, red or yellow corollas, this is not mutually exclusive and a purplish corolla form has been reported for C. scortechinii (Yong 1989) (Fig. 1d) and species such as A. indica have white corolla forms (Parnell 2012). Another general difference is that Christisonia flowers are typically on short pedicels borne on short or obscure stems that do not protrude much from the ground level, whereas Aeginetia species often have taller stems 10–40 cm long that carry the flowers clearly above ground level

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