Research Article |
Corresponding author: Korana Kocić ( korana.kocic@bio.bg.ac.rs ) Academic editor: Kees van Achterberg
© 2019 Korana Kocić, Andjeljko Petrović, Jelisaveta Čkrkić, Milana Mitrović, Željko Tomanović.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kocić K, Petrović A, Čkrkić J, Mitrović M, Tomanović Ž (2019) Phylogenetic relationships and subgeneric classification of European Ephedrus species (Hymenoptera, Braconidae, Aphidiinae). ZooKeys 878: 1-22. https://doi.org/10.3897/zookeys.878.38408
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In this study two molecular markers were used to establish taxonomic status and phylogenetic relationships of Ephedrus subgenera and species distributed in Europe. Fifteen of the nineteen currently known species have been analysed, representing three subgenera: Breviephedrus Gärdenfors, 1986, Lysephedrus Starý, 1958 and Ephedrus Haliday, 1833. The results of analysis of COI and EF1α molecular markers and morphological studies did not support this classification. Three clades separated by the highest genetic distances reported for the subfamily Aphidiinae on intrageneric level. Ephedrus brevis is separated from persicae and plagiator species groups with genetic distances of 19.6 % and 16.3 % respectively, while the distance between persicae and plagiator groups was 20.7 %. These results lead to the conclusion that the traditional subgeneric classification of Ephedrus needs revision. Species from persicae species group are raised to subgenus level as Fovephedrus Chen, 1986 and Lysephedrus syn. nov. is assigned as a junior synonym of subgenus Ephedrus. Key for identification of Ephedrus subgenera is provided. Ephedrus hyadaphidis Kocić & Tomanović sp. nov. is described and several species are confirmed as valid species for the first time. Furthermore, two species are synonymised: E. dysaphidis syn. nov. as a junior synonym of E. cerasicola and E. blattnyi syn. nov. as a junior synonym of E. plagiator.
molecular phylogeny, Ephedrus subgenera, Ephedrus hyadaphidis sp. nov.
Members of the subfamily Aphidiinae (Hymenoptera, Braconidae) display a fascinating life cycle as obligatory koinobiont parasitoids of aphids, regulating host population size and density and therefore they are considered as a beneficial insect group. Due to their importance in biological control of aphids, this is one of the most extensively investigated groups within the family Braconidae (
Approximately 40 species worldwide belong to the genus Ephedrus (
Several species from this genus were implemented in biological control programs, and some of them are commercially produced and packed as part of the cocktails containing different parasitoid agents (
Systematic position of Ephedrus within the subfamily Aphidiinae is still uncertain. There have been numerous hypotheses about which genus or group is most related to Ephedrus. Based on wing venation and several other symplesiomorphic characters, the genera Toxares Haliday, 1833 and Ephedrus were classified within the tribe Ephedrini (Mackauer, 1968), yet studies on larval morphology showed that they differ significantly (
The second uncertainty about the systematic position of the genus Ephedrus is whether or not it represents the basal group within the subfamily Aphidiinae. There are some, mostly molecular, studies which consider the tribe Praini as basal within the subfamily (
Until now, species of Ephedrus have only been used for molecular studies on the subfamily level (
We decided to investigate the taxonomic status and phylogenetic relationships of Ephedrus subgenera and species with European origin, with the combination of nuclear and mitochondrial markers and morphology. Here we propose a new subgeneric classification. Several species in this study are confirmed by molecular approach for the first time and phylogenetic relationships among European species of genus Ephedrus are presented. We describe Ephedrus hyadaphidis sp. nov., an additional member of the plagiator group, parasitoid of Hyadaphis foeniculi Passerini, 1860 on several plant species. Furthermore, we synonymise E. dysaphidis as a junior synonym of E. cerasicola and E. blattnyi as a junior synonym of E. plagiator.
Parasitoid specimens were sampled throughout Europe during the past two decades. Sampling was conducted in two ways, by net sweeping and by rearing of the parasitoids. The second method was preferred as rearing provides important data on their tri-trophic interactions. Parts of the plants infested with aphid colonies were stored in plastic containers with the lid openings covered with mesh. The samples were transported to laboratory and kept under controlled conditions until the emergence of the parasitoids. Aphids stored in 70% ethanol and plant samples were also collected and identified to species or genus level. Unfortunately, all specimens of E. lonicerae were slide mounted and thus couldn’t be used for molecular analyses (
Each specimen was examined under the ZEISS Discovery V8 stereomicroscope (Carl Zeiss MicroImaging GmbH, Gottingen, Germany). After DNA extractions, samples were dissected and slide-mounted in Berlese medium. When available, specimens were studied using the Jeol JSM–6460LV scanning electron microscope (Jeol USA, Inc., Peabody, MA, USA). Measurements for new species description were obtained using ImageJ software (
The examined material is deposited in the Insitute of Zoology, Faculty of Biology, University of Belgrade (Serbia), except for specimens of E. validus and E. koponeni that were loaned from the Zoological Museum, University of Helsinki (Finland) and 5♀9♂ of E. hyadaphidis paratypes that are deposited in the Croatian Natural History Museum, Zagreb, Croatia. Ephedrus specimens analysed in this study are presented in Suppl. material
Total genomic DNA was extracted from single individuals using the Qiagen Dneasy Blood & Tissue Kit (Qiagen, Valencia, CA, USA), following the manufacturers’ protocol. The extraction method was non destructive in order to preserve whole specimens that could be used in further studies of external morphology. Two molecular markers were used; mitochondrial cytochrome c oxidase subunit I (COI) and nuclear elongation factor 1 alpha (EF1α). The primers used for amplification of COI and EF1α fragments were LCO1490 and HCO2198 (
The sequences acquired after amplification were checked for pseudogenes, visualised in FinchTV Geospiza Inc. (Seattle, USA) and manually edited and aligned in BioEdit program (
Phylogenetic analyses of the two molecular markers yielded trees with similar branch topographies (Figs
According to the obtained results, the nominative subgenus Ephedrus is paraphyletic, consisting of two independent lineages, plagiator and lacertosus species groups. In addition to these groups E. validus, the only member of the Lysephedrus subgenus, also grouped within this clade. Moreover, E. validus is nested within the plagiator species group, forming a separate clade together with E. helleni. The second clade within the plagiator species group consists of specimens belonging to ten different species (Ephedrus blattnyi, E. cerasicola, E. dysaphidis, E. hyadaphidis sp. nov., E. koponeni, E. laevicollis, E. nacheri, E. niger, E. plagiator, and E. prociphili). One individual determined as E. blattnyi grouped with E. plagiator specimens, with the genetic distance ranging from 0.2 % to 0.7 %. The same was the case for one E. dysaphidis specimen which clustered within the E. cerasicola clade (genetic distance 0.0 %–1.6 %). Genetic distances between other species within this group vary greatly ranging from 1.1 % between E. nacheri and E. prociphili up to 7.6 % between the previous two and E. laevicollis. Ephedrus lacertosus is clearly separated as a distinct group with genetic distances from all other Ephedrus species above 8.9 %. The clade consisting of Ephedrus persicae species is the oldest within the genus and represents a separate subgenus. Within this clade all three analysed species were confirmed as valid. Additionally, within E. persicae two separate phylogenetic lines were determined with average genetic distance of 2.5 % (Fig.
Bayesian inference phylogram for cytochrome oxidase c subunit I mitochondrial sequences. Bayesian posterior probabilities above 50 % are shown. The traditional subgenera are marked in different colours: Lysephedrus (blue), Breviephedrus (green), and Ephedrus (yellow). The number of sequences with the same haplotype and countries of origin are presented in brackets. Country abbreviations: AT – Austria, BE – Belgium, CZ – Czech Republic, FI – Finland, HR – Croatia, ME – Montenegro, RS – Republic of Serbia, RU – Russia, SI – Slovenia.
With the second molecular marker EF1α, 14 sequences (four mined from GenBank), belonging to eleven species (Ephedrus cerasicola, E. helleni, E. hyadaphidis sp. nov., E. lacertosus, E. laevicollis, E. nacheri, E. niger, E. persicae, E. plagiator, E. prociphili, E. validus) were analysed. While the genetic distances between species groups and species were significantly lower than those based on COI sequences, the topography of the phylogenetic three remained similar (Fig.
The analysis of the COI molecular marker grouped sequences designated as Ephedrus sp. nov. into a distinct clade. Genetic distance parameters position sequences of this group as most closely related to E. plagiator (2.7 %–3.0 %) and other members of plagiator species group (4.3 %–8.0 %). Results of the EF1α phylogenetic analysis confirmed the position of these sequences in relation to other species.
Substantial morphological examination of all available specimens of genus Ephedrus resulted in discovery of one species new to science, designated as Ephedrus sp. nov. in the phylogenetic analysis.
Holotype ♀ from Montenegro: Durmitor-Sušica, 27.07.2012, reared from Hyadaphis foeniculi on Sanicula europaea. Paratypes: 2♂ (slide mounted) from Montenegro: Durmitor-Sušica, 27.07.2012, reared from Hyadaphis foeniculi on Sanicula europaea. 3♀6♂ from Montenegro: Crno jezero, 20.06.2004, from Hyadaphis foeniculi on Lonicera xylosteum. 5♂ from Montenegro: Durmitor-Sušica, 22.07.2004, reared from Hyadaphis foeniculi on Sanicula europaea. 5♀9♂ (2♀ mounted) from Croatia: Plitvička jezera-Milanovac, 20.06.2015, from Hyadaphis foeniculi on Anthriscus sylvestris.
The new species belongs to E. plagiator species group, due to fore wing venation. It is differentiated from other Ephedrus species by possessing considerably short first flagellar segment; F1 is 2.40–2.65 as long as wide (the closest ratio is in E. nacheri, 3.05–3.7). The new species is most closely related to E. plagiator. Beside the shorter F1, it can be distinguished from E. plagiator by a smaller number of longitudinal placodes on F2 (2–3 compared to 4–6) and wider pterostigma (4.15–4.35 compared to 4.4–4.75 in E. plagiator). The new species is a specialised parasitoid of Hyadaphis foeniculi, occurring in the Balkan Peninsula.
Female. Head (Fig.
Ephedrus hyadaphidis Kocić & Tomanović, sp. nov., female, scanning electron microscopy A Head, anterior view B Antennae, lateral view C First and second antennal segments, lateral view D Mesoscutum, dorsal view E Propodeum, dorsal view F Petiole, dorsal view G Ovipositor sheaths, lateral view H Forewing, with designated vein terminology. Abbreviations: ptl – pterostigma length, ptw – pterostigma width.
Name of the species is derived from its aphid host, Hyadaphis foeniculi.
The current species distribution is Balkan Peninsula.
Holotype is slide mounted and deposited in the collection of the Institute of Zoology, Faculty of Biology, University of Belgrade. Paratypes collected in National Park Plitvice, Croatia are deposited in the Croatian Natural History Museum, Zagreb, Croatia. The remaining paratypes are deposited at the Institute of Zoology, Faculty of Biology, University of Belgrade.
The molecular phylogenetic analysis clustered E. dysaphidis together with E. cerasicola, with the genetic distance ranging from 0.0% to 1.6%. We performed a detailed morphological examination of all available material of both species in order to test the obtained molecular results. Ephedrus dysaphidis is a species from plagiator species group, described in the study by
Material examined. E. dysaphidis: Holotype ♀ from Serbia: Belgrade, 08.05.1995, reared from Dysaphis sp. on Malus domestica. Paratypes 3♀ from Serbia: Belgrade, 08.05.1995, reared from Dysaphis sp. on Malus domestica. 1♀ from Serbia: Belgrade-Radmilovac, 22.04.1992, reared from Dysaphis sp. on Malus domestica. 3 ♀ Serbia: Belgrade-Zemun, 22.04.2014, from Dysaphis devecta Walker on Malus sp. 2 ♀ Serbia: Belgrade, 24.04.2014, from Dysaphis devecta on Malus sp. E. cerasicola: 1♀ from Montenegro: Zminje jezero, 04.08.1982. 1♀ Serbia: Belgrade-Crveni krst, 14.06.1997, from Myzus cerasi Fabricius 1775 on Prunus cerasus L. 1♀ from Serbia: Mladenovac, 11.06.1990. 1♀ from Serbia: Belgrade-New Belgrade, 17.06.1993, from Phorodon humuli Schrank, 1801 on Prunus cerasifera 1♀ from Serbia: Kopaonik, 05.07.1997, from Brachycaudus helichrysi Kaltenbach, 1843 on Myosotis sp. 2♀1♂ from Serbia: Subjel, 01.05.2017., from Dysaphis pyri Boyer de Feonscolombe, 1841 on Pyrus communis. 4♀ from Belgium: from Dysaphis plantaginea on Malus sp.
Ephedrus blattnyi is a specialised parasitoid described from one finding in the Czech Republic, reared from Pterocomma ringadhli (junior synonym of Pterocomma rufipes Hartig, 1841) on Salix caprea. Several authors during previous years questioned the validity of E. blattnyi species status. After the examination of type specimens
Analysing all obtained results (both molecular and morphological), we concluded that the current subgeneric classification of Ephedrus needs revision and here we propose a new one. Subgenus Lysephedrus
Fovephedrus radiatus Chen, 1986.
Name derived from presence of fovea on mesoscutum of type species
3Rsa vein shorter than 2Rsa (3Rsa / 2Rsa less than 1), petiole subquadrate.
F1 with smaller number of longitudinal placodes (0–3, rarely 4). Mesoscutum usually with one or two mesoscuteal foveae, sometimes lacking both. Scutellar sulcus always undivided. 3RSa shorter than 2Rsa (0.55–0.95). 3Rsb/3Rsa 2.65–3.4. Petiole short and broad, 1.3–1.5 times as long as wide, lacking post lateral excavations. Ovipositor sheaths varying from stout to slender.
Species in Europe: Ephedrus persicae Froggatt, 1904, Ephedrus chaitophori Gärdenfors, 1986, Ephedrus lonicerae Tomanović, Kavallieratos & Starý, 2009, Ephedrus tamaricis Tomanović & Petrović, 2016
For diagnosis and description see
Species. Ephedrus brevis Stelfox, 1941.
Lysephedrus Starý, 1958 syn. nov.
3Rsa longer or subequal to 2Rsa, petiole more or less elongated.
F1 with variable number of longitudinal placodes (0–5). Mesoscutum without mesoscuteal fovea, except in E. longistigmus, and rarely E. lacertosus. Scutellar sulcus undivided. 3Rsa varying from almost subequal to considerably longer compared to 2Rsa (1.1–1.5 times). 3Rsb/3Rsa 1.7–2.6. Propodeum and petiole in most species without rugosity, in E. validus very rugose. Petiole more or less elongated, with or without post lateral excavations. Ovipositor sheaths commonly slender and elongated, in some species stout and short.
Ephedrus cerasicola Starý, 1962; Ephedrus helleni Mackauer, 1968; Ephedrus koponeni Halme, 1992; Ephedrus laevicollis (Thomson, 1895); Ephedrus nacheri Quilis Perez, 1934; Ephedrus niger Gautier, Bonnamour & Gaumont, 1929; Ephedrus plagiator (Nees, 1811); Ephedrus prociphili Starý, 1982; Ephedrus vaccinii Gärdenfors, 1986; Ephedrus validus Haliday, 1833, E. hyadaphidis sp. nov.
Ephedrus lacertosus (Haliday, 1833) and E. longistigmus Gärdenfors, 1986.
1 | Scutellar sulcus divided into two (Fig. |
Breviephedrus |
– | Scutellar sulcus undivided (Fig. |
2 |
2 | 3Rsa visibly or slightly shorter than 2RS (Fig. |
Fovephedrus |
– | 3Rsa longer or subequal to 2Rs (Fig. |
Ephedrus |
Representative species of the subgenera Breviephedrus (E. brevis), Fovephedrus (E. persicae), and Ephedrus (E. plagiator). A–C Breviephedrus A mesoscutum dorsal view B petiole, dorsal view C forewing D–F Fovephedrus D mesoscutum dorsal view E petiole, dorsal view F forewing G–I Ephedrus G mesoscutum, dorsal view H petiole, dorsal view I forewing.
Continuously advancing molecular methods allow us to easily sequence gene fragments of interest and compare them with results of morphological and ecological analyses in order to obtain a clearer picture of phylogenetic relationships and evolution of the group of interest. In this study we used two molecular markers to reveal the taxonomic positions and phylogeny of species within the genus Ephedrus in Europe. As proposed by
Previous studies classified species from genus Ephedrus into three subgenera (Ephedrus, Breviephedrus (E. brevis) and Lysephedrus (E. validus)) based on morphology (
Based on the presence of the fovea on mesoscutum,
The redescribed subgenus Fovephedrus is raised from persicae species group and its inter-specific relationships are thoroughly discussed in authors’ recent study (
The fact that revealing new cryptic species within large generalist groups is an ongoing process (Derocles 2016,
Ephedrus koponeni is reported outside its known distribution, northern Europe (Finland and European part of Russia) (
The results of this study show close phylogenetic relationships among E. koponeni, E. prociphili, and E. nacheri. All three species are morphologically very similar to E. plagiator, distinguished from each other by subtle morphological differences and aphid host range (
The results of molecular analyses show that Ephedrus species, when multiple sequences for analysis are available, are rich in haplotype variety. Ephedrus plagiator is known as a broadly polyphagous species, distributed throughout Europe. Specimens analysed here were collected from various aphid hosts (Aphis Linnaeus, 1758, Brachyunguis Das, 1918, Sitobion Mordvilko, 1914, Rhopalosiphum Koch, 1854, Macrosiphum Oestlund, 1886, Anoecia Koch, 1857, Linosiphon Börner, 1944 and Pterocomma Buckton, 1879) and plants (Poa, Dactylis, Malus, Tamarix, Triticum, Sitobion, Galium, Salix, Prenanthes, Abies, Vicia, Ranunculus, Prunus, Heracleum); in 15 sequences eight haplotypes were identified, which all grouped together into one phylogenetic clade. Compared to E. persicae, where in 15 specimens 12 haplotypes (forming two clusters) were discovered (
In summary, our results show that the phylogeny of Ephedrus is more complex than previously thought. It is important to note that European species of Ephedrus comprise less than a half of currently described species, so in order to get complete insight into the phylogenetic relationships among species and their evolution, further studies are needed.
The study was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (III43001). We would like to thank Prof. Olivera Petrović Obradović (Faculty of Agriculture, University of Belgrade) for aphid identification, Plitvice (Croatia) and Durmitor (Montenegro) national parks for permits and assistance during material sampling, Zoological Museum of Helsinki University (Finland) for E. validus and E. koponeni material loans, Elena M. Davidian (Russian Institute of Plant Protection, Pushkin, Russia) for providing E. brevis specimens and Petr Starý (Laboratory of Aphidology, Institute of Entomology, Academy of Sciences of the Czech Republic) for E. prociphili samples. We thank Katica Poljak for remarkable help in collecting material in NP Plitvice.
Ephedrus specimens analysed in this study
Data type: specimens data
Estimates of evolutionary divergence between sequences
Data type: phylogenetic data