Species concepts in the psyllid genus Camarotoscena (Hemiptera, Psylloidea) associated with Populus (Salicaceae)

Species concepts in the psyllid genus Camarotoscena (Hemiptera, Psylloidea) associated with Populus (Salicaceae)

Abstract

The temperate Palaearctic genus Camarotoscena (Liviidae, Liviinae) is revised to contain ten species confirming previous morphology-based species concepts. The results of the molecular analyses were only partly conclusive, as the barcoding genes used did not provide sufficient resolution to recognise all species. Both markers showed no differences between the taxa in two species pairs: C. fulgidipennis - C. hoberlandti and C. speciosa - C. subrubescens, while cytb also failed to distinguish C. trjapitzini from C. fulgidipennis - C. hoberlandti. Morphological characters of fifth instar immatures, available for half of the species, supported the species diagnosed by adult characters. Five new synonymies are proposed: Camarotoscena subrubescens (Flor eighteen sixty-one b) equals C. ujenci Klimaszewski (nineteen eighty-two), syn. nov.; Camarotoscena bianchii Loginova (seventeen seventy-five b) equals C. pamirica Baeva (nineteen eighty-three a), syn. nov., equals C. wulingshanica Li (twenty eleven), syn. nov., equals C. wutaishanica Li (twenty eleven), syn. nov., equals C. xinjiangica Li (twenty eleven), syn. nov. The previously unknown female of C. lauta is diagnosed and its terminalia are illustrated. Illustrated identification keys are provided for the adults and, where known, for the fifth instar immatures. New country records are provided for C. fulgidipennis (India: Ladakh), C. hoberlandti (India: Ladakh), C. lauta (Turkey: Ankara) and C. trjapitzini (Iran: Tehran, Yazd; Spain). The record of C. hoberlandti from Jordan is a misidentification of C. trjapitzini. All species are, as far as known, narrowly oligophagous on Populus species (Salicaceae), and the immatures induce leaf roll galls.

Introduction

with some sixty recognised species, in addition to many hybrids. Some species or hybrids of these deciduous, broad-leaved trees are widely planted for timber, fuel, wind breaks or animal fodder.

Populus constitutes a predominantly temperate and, to a lesser extent, subtropical and tropical genus of Salicaceae.

In some mountain areas of India, such as Ladakh, poplars are among the principal cultivated tree species. Unsurprisingly, several insect species, mostly Coleoptera and Lepidoptera, inflict major damage to poplar plantations. Among the sap-sucking Sternorrhyncha developing on Populus are also psyllids, namely the species of the genera Camarotoscena Haupt, nineteen thirty-five (Liviidae, Liviinae) and Egeirotrioza Boselli, nineteen thirty-one (Triozidae), as well as one species of Anomoter- ga Klyver, nineteen thirty-two, viz. A. unicolor (Loginova, nineteen fifty-eight) (Liviidae, Liviinae). These taxa are Palaearctic while no psyllids are known to develop on poplars in North America or sub-Saharan Africa.

For the study and control of any pest, a sound taxonomic base is crucial. This base is available for Egeirotrioza and A. unicolor, but the identification of Camarotoscena species remains problematic. Camarotoscena species occur in the southern latitudes of the temperate deciduous forest belt from the Mediterranean Basin to the Far East. The genus is most species-rich in the arid mountain regions of Asia. Information on the distribution and biology is sketchy and sometimes inaccurate. Loginova reviewed the genus based on adult morphological characters and provided a key for the identification of adults. She concluded that the genus is morphologically 'monolithic' with minor differences between species. In particular, the male and female terminalia, providing usually reliable diagnostic characters, are unusually homogeneous.

Loginova recognised thirteen species, three of which were transferred to Diclidophlebia Crawford, nineteen twenty (Camarotoscena species equals D. xuani Messi, in Messi et al., nineteen ninety-eight) or Anomoter- ga Klyver (C. africana Loginova, nineteen seventy-five and C. unicolor). Li and Yang described Camarotoscena huashana Li and Yang, nineteen eighty-nine, which was synonymised with C. personata Loginova, nineteen seventy-five. Camarotoscena ujenci Klimaszewski, nineteen eighty-two was erected for two males from Mongolia. Baeva added a species from Tadzhikistan (Camarotoscena pamirica Baeva, nineteen eighty-three) and Li three species from China (Camarotoscena wulingshanica Li, twenty eleven, C. wutaishanica Li, twenty eleven, C. xinjiangica Li, twenty eleven), all four based on one or two females only. The three species from China were synonymised with C. bianchii Loginova, nineteen seventy-five by Luo in his Ph. D. thesis, a nomenclatural act which is not valid according to the ICZN. The twelve currently recognised species are probably oligophagous on Populus and possibly induce roll galls on the poplar leaves. The fifth instar immature has been described only for C. speciosa (Flor, eighteen sixty-one). It is not uncommon that closely related psyllid species develop on the same plant species and often on the same plant individual. In Camarotoscena, the two species pairs C. speciosa and C. subrubescens (Flor, eighteen sixty-one) (Flor eighteen sixty-one a, b; present paper) as well as C. fulgidipennis Loginova, nineteen seventy-five and C. hoberlandti Vondráček, nineteen fifty-two (present paper) have been collected together, some possibly on the same plants.

For psyllids, as for other insects, DNA barcoding is a useful and relatively quick and inexpensive tool broadly used for species identification, especially when morphological and ecological data provide insufficient diagnostic characters. A three percent cytochrome C oxidase subunit one threshold is commonly applied for species delimitation, although divergence levels can vary between and even within genera. This marker has been successfully used to delimit species of several genera from all seven currently recognised psyllid families, although with some exceptions. For example, the genetic difference in COI was less than one percent between the morphologically similar Aphalara avicularis Ossian- nilsson, nineteen eighty-one and A. freji Burckhardt and Lauterer, nineteen ninety-seven, while the intraspecific difference reached up to fourteen percent between specimens from the same or different populations in several Melanastera species. Similar patterns were encountered with the cytochrome B marker, which is often more variable and less frequently used for delimitating thresholds, but which generally supports the same species-level clusters as COI. Although species of Camarotoscena have never been compared using DNA barcodes, sequences of three species are already available.

In the current study, we review Camarotoscena by comparing the results from morphological and molecular analyses. As species in this genus are morphologically homogeneous, we examine whether DNA barcodes provide more reliable means of identification and whether their genetic divergences show congruence with morphological boundaries. We provide identification keys to adults and, where known, to fifth instar immatures. Illustrations are provided for selected species.