New morphological and DNA evidence supports the existence of Calligonum jeminaicum Z. M. Mao (Calligoneae, Polygonaceae) in China.

Wei Shi,Jun Wen,Borong Pan,Pei-Liang Liu,Ying Feng

doi:10.3897/phytokeys.132.34981

Abstract

Calligonum jeminaicum Z. M. Mao, a species regarded as endemic to China, was thought to be nonexistent owing to a lack of scientific records. The similarity of C. jeminaicum to C. mongolicum Turcz. warranted an investigation into the taxonomical relationship between these species. In this study, a naturally occurring population of C. jeminaicum was discovered and the taxonomical relationships of this species with C. mongolicum were resolved. Morphological traits, including fruit and flower characteristics, as well as nuclear (ETS, ITS) and chloroplast (psbA-trnH, ycf6-psbM, rpl32-trnL, rbcL, and trnL-F) DNA sequence data were studied to confirm the taxonomic status of C. jeminaicum. The nrDNA data (ITS1-2 and ETS) from C. jeminaicum reflected variability from the whole C. mongolicum complex, showing distinctive haplotypes in the Calligonum sect. Medusa Sosk. & Alexandr. The cpDNA data supplied similar evidence, showing unique branching in Bayesian and ML tree analyses. The specific status of C. jeminaicum is confirmed based on both morphological and molecular analyses. Here we present a revised description of C. jeminaicum along with its DNA barcode and discuss suggestions for the conservation of this species. Based on current evidence, this species was evaluated as Critically Endangered (CR) according to the IUCN criteria.

Highlights

Calligonum L. species are as ecologically important as some of the dominant shrubs and semi-shrubs in both active and inactive sand dunes in the African Sahara (Dhief et al 2011, 2012) and the deserts of Central Asia (Losinskaya 1927; Bao and GrabovskayaBorodina 2003; Amirabadi-zadeh et al 2012)
The classical identification key was used to differentiate these species mainly based on fruit characteristics and geographic locations, and the C. mongolicum complex has been identified by its fruit characteristics (Mao 1992; Bao and Grabovskaya-Borodina 2003), primarily based on quantifiable differences in fruit and bristle size, such as fruit length (LF), fruit width (WF), bristle length (BS), bristle distance (BD), rib distance (RD), achene length (AL), achene width (AW), and fruit shape (FF) (Shi et al 2012, 2016; Fig. 2A)
Some fruit characters appeared simultaneously in the two species and led to difficulty in distinguishing C. jeminaicum from C. mongolicum, the shape of perianth segments in fruit could be regarded as an effective character for their identification (Fig. 2D)

Summary

Introduction

Calligonum L. species are as ecologically important as some of the dominant shrubs and semi-shrubs in both active and inactive sand dunes in the African Sahara (Dhief et al 2011, 2012) and the deserts of Central Asia (Losinskaya 1927; Bao and GrabovskayaBorodina 2003; Amirabadi-zadeh et al 2012). They are natural resources of tannins, food, medications, nectar, and antidotes (Liu et al 2001; Badria et al 2007; Askariyahromi et al 2013; Essam et al 2014). There has been no further record of this species to demonstrate its existence, leading to the question: does this endemic species exist? This question was resolved by specific field work in 2013 when a naturally occurring population with eight individuals of C. jeminaicum was found

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Conclusion