A revision of European species of the genus Tetrastichus Haliday (Hymenoptera: Eulophidae) using integrative taxonomy

Christer Hansson; Stefan Schmidt

doi:10.3897/BDJ.8.e59177

Biodiversity Data Journal : Taxonomic Paper

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Taxonomic Paper

A revision of European species of the genus Tetrastichus Haliday (Hymenoptera: Eulophidae) using integrative taxonomy

Christer Hansson^‡,§, Stefan Schmidt^|

‡ The Natural History Museum, London, United Kingdom

§ Biological Museum (Entomology), Lund University, Lund, Sweden

| SNSB-Zoologische Staatssammlung München, Munich, Germany

Corresponding author: Christer Hansson (christerdennis@gmail.com), Stefan Schmidt (schmidt.s@snsb.de)

Academic editor: Simon van Noort

Received: 30 Sep 2020 | Accepted: 20 Nov 2020 | Published: 16 Dec 2020

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: Hansson C, Schmidt S (2020) A revision of European species of the genus TetrastichusHaliday (Hymenoptera: Eulophidae) using integrative taxonomy. Biodiversity Data Journal 8: e59177. https://doi.org/10.3897/BDJ.8.e59177

ZooBank: urn:lsid:zoobank.org:pub:AD70B3AB-6763-4D28-85F2-90988225C5C8

Abstract

Background

The European species of the genus Tetrastichus (Insecta, Hymenoptera, Eulophidae, Tetrastichinae) are revised with 93 species, including 50 species described as new. The revision was conducted using an integrative taxonomic approach, based on DNA barcoding in combination with morphological characters. The Tetrastichinae are a biologically diverse and species-rich group of parasitoid wasps with numerous complexes of morphologically often very similar species that attack a wide range of hosts in over 100 insect families in 10 different orders. The genus Tetrastichus is, with almost 500 described species, the third largest genus of Tetrastichinae. Although biological information is lacking for most species, current data indicate that Tetrastichus species are gregarious koinobiont endoparasitoids developing on juvenile stages of mainly holometabolous insects. Due to their host specificity, several species of Tetrastichus are used as biological control agents.

New information

The European species of Tetrastichus Haliday (Hymenoptera: Eulophidae) are revised using a combination of externo-morphological and DNA barcoding data. This is the first integrative approach for any of the large genera of the Tetrastichinae. A total of 93 species are included, of which 50 are described as new: T. agonus sp. n., T. antonjanssoni sp. n., T. argei sp. n., T. argutus sp. n., T. asilis sp. n., T. ballotus sp. n., T. bledius sp. n., T. broncus sp. n., T. calcarius sp. n., T. calmius sp. n., T. clisius sp. n., T. cosidis sp. n., T. cumulus sp. n., T. cyprus sp. n., T. delvarei sp. n., T. doczkali sp. n., T. elanus sp. n., T. elodius sp. n., T. ennis sp. n., T. enodis sp. n., T. erinus sp. n., T. evexus sp. n., T. fadus sp. n., T. fenrisi sp. n., T. flaccius sp. n., T. gredius sp. n., T. iasi sp. n., T. illydris sp. n., T. incanus sp. n., T. inscitus sp. n., T. intruitus sp. n., T. johnnoyesi sp. n., T. lacustrinus sp. n., T. ladrus sp. n., T. lanius sp. n., T. lazius sp. n., T. lixalius sp. n., T. lycus sp. n., T. marcusgrahami sp. n., T. minius sp. n., T. mixtus sp. n., T. nataliedaleskeyae sp. n., T. nymphae sp. n., T. pixius sp. n., T. scardiae sp. n., T. splendens sp. n., T. sti sp. n., T. suecus sp. n., T. tacitus sp. n. and T. tartus sp. n. Two keys for the identification of species are presented, one for females and one for males. Based on DNA barcode sequences for 70 of the species, a Maximum Likelihood tree to assess phylogenetic relationships within the genus is presented. These 70 species are also characterised by a combination of CO1 and morphological data. The remaining 23 species, without a DNA barcode, are characterised by morphological data. Using a combination of data from the morphology and CO1 or morphological data only, the species are separated into three species groups (clito-, hylotomarum-, murcia-groups) with 41 unplaced species outside these groups. Hosts are known for 27 of the species and they are gregarious, koinobiont endoparasitoids on a wide range of immature stages of holometabolous insects and appear to be very host specific. The first host record for Lepidoptera (Tineidae) in Europe is included.

Keywords

integrative taxonomy, DNA barcoding, new species, parasitoids, Tetrastichinae, taxonomic revision, morphology, parasitoid, gregarious endoparasitoids, distribution.

Introduction

Tetrastichinae

The Tetrastichinae (Hymenoptera: Eulophidae) are one of the largest groups of parasitoid Hymenoptera. They are, with currently about 1650 species in 91 genera, the largest subfamily of the family Eulophidae, that include 297 genera and about 4500 species (Noyes 2020). Species of tetrastichines are found throughout the world and they occur in most habitats on Earth. The majority of species has been described and recorded from the temperate parts and mainly from Europe, but very little is known about this group from tropical areas. Thus, the recorded number of species is very probably a minor part of the actual number. Apart from species richness, it is also one of the biologically most diverse groups of parasitoids and the range of tetrastichine hosts comprise over 100 insect families in 10 different orders and, in addition, spider eggs and even (through their galls) mites and nematodes are targeted (LaSalle 1994).

The subfamily is a group of particular importance, even within parasitoid wasps that are generally essential for maintaining biological diversity in terrestrial ecosystems (LaSalle and Gauld 1991, LaSalle 1994, LaSalle and Gauld 1993). It is extremely species-rich and has been used in numerous ecological, biological and behavioural studies and several species have been successfully used as biological control agents (see Graham (1987), LaSalle (1994) and references therein). Despite their importance, virtually all genera lack comprehensive taxonomic revisions and the identification of species from most geographic regions is hampered by the lack of identification tools. Furthermore, the classification of Tetrastichinae has been subject to major re-arrangements throughout the history of the subfamily since it was established by A. Förster (Förster 1856) and is treated in further detail below for the genus Tetrastichus.

Taxonomists have largely ignored tetrastichines because they are taxonomically extremely difficult due to a large number of species and their morphological similarity. Both factors have been a major obstacle for taxonomic revisions, based on morphological characteristics. For the present study, we chose an integrative taxonomic approach, based on DNA barcoding combined with features in the external morphology. Barcoding allows for sequencing large numbers of specimens at a reasonable cost and it provides a standardised set of molecular characters that, together and in combination with morphological data, can be used to assess species boundaries. Examination of morphology allows the inclusion of species for which DNA data could not be gathered, for example, museum specimens of rare species that are often very old and pose problems for DNA sequencing.

The genus Tetrastichus

The genus Tetrastichus has been attributed to Haliday (1844), even though it was first described by Walker in 1842, but the Walker name has been suppressed by the International Commission on Zoological Nomenclature (1965). Haliday included a single species (Cirrospilus attalus Walker (= T. miser (Nees)) which then became the type species for Tetrastichus. The subsequent fate of Tetrastichus has been quite turbulent. Burks (1943) gives a detailed account of nomenclatural and classificatory events up to his publication. The history after 1943 is equally turbulent. Graham (1961) synonymised Tetrastichus with Aprostocetus Westwood (priority made Aprostocetus senior to Tetrastichus) and recombined all European species previously in Tetrastichus to Aprostocetus. Domenichini (1966) rejected this action by Graham, resurrected Tetrastichus and recombined all species back to Tetrastichus. Bouček (1977) published a key to all genera of Tetrastichinae and maintained the wide interpretation of Tetrastichus by Domenichini, as did Kostjukov (1977). Graham (1987) revised the classification of European genera in Tetrastichinae and kept Tetrastichus as a valid genus, but now in a very restricted sense, including only species in the so-called miser-group (sensu Graham (1961)Domenichini (1966)). The remainder of the species in Tetrastichus s.lat. were recombined to other existing, or newly created, genera. The bulk of species were transferred to Aprostocetus, which then became a very large genus with several hundred species on a world basis. Bouček (1988) and LaSalle (1994) followed the classification proposed by Graham. Finally, Graham (1991) revised the European species of Tetrastichus s.str., including 42 species, of which 20 were described as new. The species were classified into six species groups and with three unplaced species. In this publication, we follow the definition of Tetrastichus proposed by Graham (1987), Graham (1991).

Tetrastichus species have been found on all continents (Bouček 1988, Graham 1991, LaSalle 1994) and it is the third largest genus of the subfamily Tetrastichinae, after Aprostocetus and Baryscapus Förster (LaSalle 1994), including hundreds of species. Noyes (2020) lists 492 species names in the genus, but, due to the chaotic history of Tetrastichus, it is difficult to establish how many of these names actually represent species of Tetrastichus s.str. without examining the type specimens.

Biology

Biological information is known for about one-third of the species (29 out of 93) treated here. The available information from literature and from our own experience strongly indicate that Tetrastichus species are gregarious koinobiont endoparasitoids developing on juvenile stages of mainly holometabolous insects from all the four major orders: Coleoptera, Diptera, Hymenoptera and Lepidoptera (Table 1). Most species are associated with Coleoptera and mainly with phytophagous and xylophagous groups (Buprestidae, Cerambycidae, Chrysomelidae and Curculionidae). The Diptera host groups include a wide range of biologies: saprophagous (Brachyopa spp. Sargus sp.), xylophagous (Xylomyia cabrerae) and gall-making (Lipara lucens) species. In Hymenoptera, larvae and pupae of sawflies (Argidae, Tenthredinidae) are targeted. Prior to this article, no host was recorded from Lepidoptera in Europe, but here we present the first record from this order, Scardia boletella (Fabricius) (Tineidae), that develops in different species of shelf fungi. According to Bouček (1988), Indo-Australian species of Tetrastichus frequently target Lepidoptera, mainly various moths in rice fields, emerging from host pupae and sometimes also act as hyperparasitoids. The Neotropical species T. periplanetae Crawford targets cockroach oothecae (LaSalle 1994).

Table 1.

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Tetrastichus hosts

Tetrastichus species	Host
T. agrilocidus Graham	Agrilus sp. (Coleoptera: Buprestidae), Xylotrechus pantherinus Savenius (Coleoptera: Cerambycidae) (Graham 1991)
T. argei sp. n.	Gregarious endoparasitoid on Arge ustulata (L.) (Hymenoptera: Argidae)
T. atratulus (Nees)	Ptecticus tenebrifer (Walker) (Diptera: Stratiomyiidae) (in Japan) (Graham 1991)
T. brachyopae Graham	Gregarious koinobiont endoparasitoid on Brachyopa spp. (Diptera: Syrphidae), clutch size varying from 7–18 specimens, with a strong female bias (van Eck et al. 2016). Recorded from Brachyopa pilosa Collin (Graham 1991), B. bicolor (Fallén) & B. insensilis Collin (van Eck et al. 2016)
T. clito (Walker)	Cassida murraea L., C. rubiginosa Müller, C. deflorata Suffrian (Graham 1991), C. humeralis Kraatz new record. All hosts are Coleoptera: Chrysomelidae
T. coeruleus (Nees)	Crioceris asparagi (Coleoptera: Chrysomelidae), emerges from host cocoons, but oviposits already in the host eggs (Graham 1991)
T. crioceridis Graham	Crioceris duodecimpunctata L. (Coleoptera: Chrysomelidae), egg-larval parasitoid (Graham 1983)
T. cyprus sp. n.	Reared from an unidentified Coleoptera and from an unidentified leaf miner on broad bean (Vicia faba L.)
T. epilachnae (Giard)	Epilachna argus (Geoffroy in Fourcroy), E. chrysomelina F., Subcoccinella vigintiquattropunctata L. (Coleoptera: Coccinellidae) (Graham 1991)
T. halidayi (Graham)	Agropus ahrensi Germar (Coleoptera: Chrysomelidae) (Graham 1991)
T. heeringi Delucchi	Agrilus aurichalceus Redtenbacher, A. integerrimus Ratzeburg, A. viridis (L.) (Coleoptera: Buprestidae) (Graham 1991)
T. hylotomarum (Bouché)	Arge ochropus (Gmelin), A. pagana (Panzer) (Hymenoptera: Argidae), Athalia cordata Audinet-Serville, Cladius pectinicornis (Geoffroy) (Hymenoptera: Tenthredinidae), parasitising host larvae and pupae (Graham 1991)
T. julis (Walker)	Lema (Oulema) spp. (Coleoptera: Chrysomelidae), gregarious endoparasitoid of host larva (Graham 1991)
T. legionarius Giraud	Gregarious endoparasitoid of larvae and pupae of Lipara lucens Meigen (Diptera: Chloropidae) (Graham 1991)
T. leocrates (Walker)	Rhynchaenus alni (L.) (Graham 1991), R. testaceus (Müller) (new record) (Coleoptera: Curculionidae)
T. lyridice (Walker)	Plagiodera versicolora (Laich.)? (Coleoptera: Chrysomelidae). This record is doubtful, needs checking (Graham 1991)
T. macrops (Graham)	Probably Cis spp. (Coleoptera: Cisiidae) in Polyporaceae (Graham 1991)
T. melosomae Graham	Chrysomela vigintipunctata (Scopoli) (Coleoptera: Chrysomelidae) (Graham 1991)
T. miser (Nees)	Rhynchaenus alni (L.), R. fagi (L.), R. pilosus (F.), R. quercus (F.), R. salicis (L.), Ramphus oxyacanthae (Marsham) (Coleoptera: Curculionidae) (Graham 1991)
T. murcia (Walker)	Geosargus sp. (Diptera: Stratiomyiidae), endoparasitoid emerging from pupa (Domenichini 1966)
T. nymphae sp. n.	Gregarious endoparasitoid on Galerucella nymphaeae (L.) (Coleoptera: Chrysomelidae)
T. pilemostomae Graham	Pilemostoma fastuosa (Schaller) (Coleoptera: Chrysomelidae) (Graham 1991)
T. polyporinus Askew	Possibly Dacne sp. (Askew 2007); Triplax rufipes Fabricius and T. russica (L.) new records. All hosts are Coleoptera: Erotylidae
T. scardiae sp. n.	Scardia boletella (Fabricius) (Lepidoptera: Tineidae)
T. setifer Thomson	Lilioceris lilii (Scopoli) (Gold et al. 2001) and L. tibialis (Villa) (Kenis et al. 2002) (Coleoptera: Chrysomelidae)
T. solvae Graham	Xylomyia cabrerae (Becker) (Diptera: Xylomyiidae) in twigs of Euphorbia canariensis (Graham 1991)
T. telon (Graham)	Agrilus viridis L. (Coleoptera: Buprestidae) (Domenichini 1966)
T. temporalis (Graham)	Associated with Phalaris arundinacea (Poaceae) (Graham 1991)
T. ulmi Erdös	Scolytus rugulosus (Müller) and Leperisinus orni Fuchs (Coleoptera: Scolytidae), Agrilus sp. and possibly Anthaxia sp. (Coleoptera: Buprestidae) (Graham 1991)

Van Alphen (1980) investigated the life history of T. coeruleus (as T. asparagi) and T. crioceridis (as an undescribed Tetrastichus species). Both species are parasitoids of Crioceris spp. (Coleoptera: Chrysomelidae) on asparagus (Asparagus officinalis), T. coeruleus on C. asparagi and T. crioceridis on C. duodecimpunctata. The females of both species oviposit in eggs with advanced embryos or in the larvae of their respective host. Both species are monophagous and, in spite of occurring on the same host plant, they do not overlap with each other. In another paper, Duan et al. (2011) outlined the life history of T. planipennisi Yang. Tetrastichus planipennisi is an Asiatic species targeting the emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae). The wasp female oviposits in larval stages 2-4 and it took about four weeks to complete the development from egg to adult wasp.

The sex ratio of clutches is female biased (e.g. Duan et al. 2011 and through experiences from our own rearings). In some cases, no males have been reared, suggesting thelytoky, for example, T. coeruleus in North America (Graham 1991).

Materials and methods

Morphology

Species of Tetrastichus are, like most other Tetrastichinae, taxonomically exceptional amongst Eulophidae because of their high morphological similarity, hampering a taxonomic revision, based on morphology alone. Unless collected through rearing when the host is known, species of Tetrastichus are very difficult from which to get a series of specimens. Sweep netting and Malaise trapping only yield one or a few specimens at best per collecting event. The rarity of many species, with only very few specimens of each species available for study, prevents the assessment of intraspecific variation and further complicates the definition of species borders. To alleviate the situation, for the present study, an integrative approach was employed, with DNA barcoding as a first step to obtain operational taxonomic units that were subsequently examined morphologically, using criteria that were traditionally used for delimiting species, i.e. morphologically diagnostic characters. In the absence of sufficient morphological differences between OTUs, a conservative approach was followed in that the OTUs were regarded as conspecific until further evidence is available to assess their species status. In these cases, additional genetic markers are needed to disentangle complexes of closely-related species. In several species, the taxonomy has to rely on very few specimens, often with even fewer DNA barcodes and their species status will need to be evaluated as further specimens (and sequence data) become available. Furthermore, the number of species in Europe is probably much higher than currently known and there is, thus, a high probability that species of Tetrastichus that are not included in the present revision will be encountered in the future, in particular with material that is collected in areas other than the main study area in this article and in Graham (1991), i.e. Northern and Central Europe. For these reasons, DNA barcodes, in combination with a thorough morphological examination, will be essential for accurate species level identifications ofTetrastichus.

DNA sequencing

For DNA extraction, whole specimens were sent to the Canadian Centre for DNA Barcoding (CCDB) in Guelph, Canada, for DNA extraction and barcode sequencing and subsequent recovery of vouchers for preparation and morphological study. A complete list of voucher specimens included in the revision is given in Suppl. material S1. DNA extraction, PCR amplification and sequencing were conducted at CCDB, using standardised high-throughput protocols (Ivanova et al. 2006, deWaard et al. 2008). The 658 bp target region, starting from the 5’ end of the mitochondrial cytochrome c oxidase I (COI) gene, includes the DNA barcode region of the animal kingdom (Hebert et al. 2003). The DNA extracts are stored at CCDB. Specimens that were successfully sequenced are listed in Suppl. material S1. All specimen data are accessible in BOLD as a single citable dataset (dx.doi.org/10.5883/DS-TTSEUR).

The data include collecting locality, geographic coordinates, elevation, collector, one or more digital images, identifier and voucher depository. Sequence data can be obtained through BOLD and include a detailed LIMS report, primer information and access to trace files. The sequences are also available on GenBank (for accession numbers, see Suppl. material S1).

Due to the expected presence of complexes of cryptic species, i.e. species that are morphologically virtually indistinguishable, all suitable specimens were subjected to DNA barcoding, even at the risk of obtaining a long series of the same species. The final BOLD dataset (DS-TTSEUR) contains 1,128 specimen records, 1,126 of which are associated with a DNA sequence. Amongst the specimens with a barcode sequence, 860 were assigned a Barcode Index Number (BIN) by the BOLD system, resulting in 73 species with one or more BINs. A total of 60 species were represented by a single BIN, 24 species with two BINs and one species (T. sinope) with three BINs (with a single specimen each).

The initial concerns with obtaining multiple sequences of the same species turned out to be unwarranted. A total of 22% of the species were represented by singletons, almost two thirds (63%) by 1-5 specimens and only two species with over 100 specimens each (Fig. 1). The species with the largest number of specimens in our dataset includeTetrastichus atratulus (178 specimens), T. halidayi (155 specimens), followed by T. miser (80 specimens), T. temporalis (62 specimens), T. lyridice (34 specimens) and T. leocrates (31 specimens). The remaining 67 species were represented by at most 25 specimens.

Figure 1.

Number of specimens of 73 Tetrastichus species that were analysed by DNA barcoding.

Data analysis

Sequence divergence statistics were calculated using the Kimura two parameter model of sequence evolution (Kimura 1980). Barcode Index Numbers (BINs) were assigned by the BOLD system, representing globally-unique identifiers for clusters of sequences that correspond closely to biological species (Ratnasingham and Hebert 2013). For BIN assignment, a minimum sequence length of 500 bp is required and sequences between 300 and 500 bp can join an existing BIN, but will not create or split BINs. In the present study, BINs were used to delineate Molecular Operational Taxonomic Units (MOTUs) prior to a detailed taxonomic study, based on morphological characters. Sequences were aligned using the BOLD Aligner (amino acid-based hidden Markov models). The analyses are based on sequences with a minimum length of 500 bp and less than 1% ambiguous bases. Genetic distances and summary statistics were calculated using analytical tools in BOLD and are given as mean and maximum pairwise distances for intraspecific variation and as minimum pairwise distances for interspecific variations.

For phylogenetic analyses, the COI sequences were aligned using Muscle (Edgar 2004). Maximum Likelihood (ML) trees were inferred using IQ-TREE, version 2.0.6 (Minh et al. 2020). The best-fit substitution models were inferred separately for the DNA sequence and the gap data partitions using ModelFinder (Kalyaanamoorthy et al. 2017) as implemented in IQ-TREE, prior to tree reconstruction. Branch support was estimated with ultrafast bootstrap estimation (Hoang et al. 2018) using 10,000 bootstrap replicates. The phylogenetic inferences were based on sequences with a minimum length of 500 bp, resulting in a dataset with 748 sequences.

Museum acronyms

ETHZ Swiss Federal Institute of Technology, Entomological Collection, Zürich, Switzerland; GD Private collection of Gérard Delvare, Montpellier, France; HNHM Hungarian Natural History Museum, Budapest, Hungary; MZLU Biological Museum, Entomology, Lund University, Sweden; NHM the Natural History Museum, London, United Kingdom; NHRS Swedish Museum of Natural History, Stockholm, Sweden; NMW Naturhistorisches Museum, Wien, Austria; OUMNH Oxford University Museum of Natural History, United Kingdom; SMTP Swedish Malaise Trap Project, Station Linné, Ölands Skogsby, Sweden; UCRC University of California, Riverside, Entomology, USA; USNM United States National Museum of Natural History, Washington, D.C., USA; ZSM SNSB-Zoologische Staatssammlung München, Munich, Germany.

Abbreviations of morphological terms and nomenclature

With some exceptions (below), the morphological terms used here are explained and illustrated (figs. 6–12) in Graham (1987). Abbreviations of morphological terms not used in Graham (1987): Gt_1-7 gastral tergites 1–7; MG median groove on mid-lobe of mesoscutum (as median line in Graham (1987), Graham (1991)); MV marginal vein; OD diameter of lateral ocelli; ST stigmal vein; SLG sublateral groove on mesoscutellum (as sublateral line in Graham (1987), Graham (1991)); SMG submedian groove on mesoscutellum (as submedian line in Graham (1987), Graham (1991)); T1–4 tarsomeres 1–4.

To avoid the problems associated with the requirement by the International Code of Zoological Nomenclature (International Commission of Zoological Nomenclature 1999) that the gender of species names must agree with that of the genus, we follow Noyes (2004) in that all new names proposed in the present study, except indicated otherwise, must be treated as arbitrary combinations of letters or nouns in apposition. As a consequence, species names will not change if species are transferred to a genus with a different gender at any time in the future.

Imaging

The colour images of the type specimens of previously-described species were made using Canon camera equipment including an EOS 5D Mark IV body, MP E-65 macro lens and macro twin lite MT-24 EX. The camera was attached to a Cognisys stackshot macro rail system. The images of type specimens for the newly-described species were done with the same equipment, except that the macro lens was substituted with a Canon tele-zoom lens, 70–300 mm (using only 135 & 200 mm), with a 10× Mitutoyo microscope lens attached. The picture stacking was done with Helicon Focus version 6 software and Adobe Photoshop was used for image processing.

The SEM micrographs are from uncoated specimens and were done with a Hitachi SU 3500 scanning electron microscope, in low vacuum.

Taxon treatments

Tetrastichus Haliday, 1844

Nomenclature

Tetrastichus Haliday 1844:297–298. Type species Cirrospilus attalus Walker, by monotypy (=T. miser (Nees)). Not Tetrastichus Walker 1842:116, a name suppressed by the International Commission on Zoological Nomenclature (1965).

For a complete list of synonyms, see Graham (1991).

Diagnosis

European species of Tetrastichus can be diagnosed by a combination of three features: submarginal vein in fore wing with one dorsal seta, mid-lobe of mesoscutum with at least three adnotaular setae on each side and propodeum with a ± complete lateral longitudinal carina that splits into two in posterior part (like an inverted "Y", Fig. 2c). In addition, most species have a strong exoskeleton, preventing specimens from collapsing when dried. This last feature is not unique to Tetrastichus, but in combination with the other three features, it helps when diagnosing this group.

Figure 2.

Tetrastichus spp.

a: T. legionarius female nontype, ovipositor sheaths protruding beyond Gt7, lateral view.
b: T. coeruleus female nontype, ovipositor retracted, ventral view.
c: T. halidayi female nontype, propodeum, dorsal view.
d: T. legionarius male nontype, antennal F1-F3, lateral view.
e: T. leocrates male nontype, antennal F1-F3, lateral view.

Identification keys

Figs 2, 3:The identification keys are based on the two keys in Graham (1991), one for females and one for males, with the new species included and with some modifications of features included and order of couplets slightly changed. The main reason for keeping the sexes apart is that differences between species are frequently based on features unique to each sex (antennal characteristics and length of female gaster). Since males are unknown for several of the species, the male key is distinctly shorter than the female key.

Figure 3.

Tetrastichus spp.

a: T. halidayi female nontype, head, frontal view.
b: T. clito female nontype, head, frontal view.
c: T. halidayi female nontype, hind coxa, lateral view.
d: T. clito female nontype, hind coxa, lateral view.

Figure 4.

Tetrastichus antonjanssoni sp. n.

a: Holotype female, lateral.
b: Holotype female, dorsal.

Figure 5.

Tetrastichus atratulus (Nees)

a: Neotype female, lateral.
b: Neotype female, dorsal.
c: Nontype female, head frontal.
d: Nontype male, head and antenna lateral.

Figure 6.

Tetrastichus brachyopae Graham

a: Holotype female, dorsal
b: Holotype female, dorso-lateral.
c: Nontype female, lateral.
d: Nontype female, head frontal.

Tetrastichus murcia group

Diagnosis

Eyes with long setae (e.g. Fig. 7d); female antenna with relatively short flagellomeres and with a distinct clava (e.g. Fig. 5a); male flagellomeres 1–4 with an externo-dorsal, sub-basal compact whorl of long setae (e.g. Fig. 5d); setae along hind margin of pronotum and adnotaular setae on mesoscutum long and erect (e.g. Fig. 7a); body black non-metallic or with weak metallic tinges; female gaster circular or short ovate.

Figure 7.

Tetrastichus dasyops Graham

a: Holotype female, lateral.
b: Holotype female, dorsal.
c: Nontype male, head & antenna lateral.
d: Nontype female, head frontal.

Tetrastichus antonjanssoni, sp. n.

ZooBank urn:lsid:zoobank.org:act:BD5F1E7B-17EB-4401-96CA-C18F233A1A11

Material Download as CSV

Holotype:

scientificName:
Tetrastichus antonjanssoni
; taxonRemarks:
Holotype deposited in MZLU
; phylum:
Arthropoda
; class:
Insecta
; order:
Hymenoptera
; family:
Eulophidae
; genus:
Tetrastichinae
; country:
Sweden
; decimalLatitude:
59.2753
; decimalLongitude:
15.2134
; individualID:
BC-ZSM-HYM-29813-C08
; individualCount:
1
; sex:
female
; lifeStage:
adult
; catalogNumber:
BC-ZSM-HYM-29813-C08
; occurrenceDetails:
http://www.boldsystems.org/index.php/API_Public/specimen?ids=BC-ZSM-HYM-29813-C08
; recordNumber:
BC-ZSM-HYM-29813-C08
; recordedBy:
Anton Jansson
; type:
PhysicalObject
; language:
en
; institutionCode:
MZLU
; basisOfRecord:
PreservedSpecimen

Description

FEMALE holotype (Fig. 4). Body length 1.5 mm. Head. Width/length (dorsal view) 2.3, width/length (frontal view) 1.2, POL/OOL 2.2, widths head/mesosoma 1.1, mouth width/malar space 1.0, malar space/eye height 0.8. Antenna. Scape length/eye height 1.0, pedicel+flagellum length/mesosoma width 1.2, length/width F1, F2, F3 1.6, 1.4, 1.1, clava length/width 2.2, lengths pedicel/F1 0.8, lengths F1/F2 1.1, F1/F3 1.2, lengths F1, F2, F3/clava 0.5, 0.5, 0.5, widths F1/pedicel (dorsal view) 1.4, lengths antennal spicule/C3 0.3. Mesosoma. Length/width 1.3, mesoscutal midlobe length/width (width measured in anterior part) 0.8, mid-lobe with median groove in posterior ½, with three adnotaular setae on each side, lengths mesoscutum/mesoscutellum (measured medially) 1.2, mesoscutellum length/width 0.8, length/width of enclosed space between submedian grooves 2.1, distance between SMG/distance between SMG and SLG 1.7, lengths dorsellum/propodeum (measured medially) 0.5, propodeum with strong reticulation, propodeal callus with four setae. Fore wing. Costal cell length/width 12.5, lengths costal cell/marginal vein 1.0, lengths marginal/stigmal veins 3.1. Gaster. Subcircular to ovate, length/width 1.7, lengths gaster/mesosoma 1.1, Gt₇ length/width 0.4, length longest seta of each cercus/next longest seta 1.6, longest cercal seta nearly straight, ovipositor sheaths projecting slightly beyond apex of Gt₇.

Colour. Body with weak metallic greenish-blue tinges, scape yellowish-brown with dorsal edge brown, pedicel and flagellum dark brown, tegulae dark brown, wings hyaline with veins pale yellowish-brown, coxae and femora concolorous with body, trochanters dark brown, tibiae and tarsi yellowish-brown.

MALE. Unknown.

Diagnosis

Antenna very short with F1 1.6×, F2 1.4×, F3 1.1× and clava 2.2× as long as wide; POL/OOL 2.2; distance between SMG 1.7× distance SMG to SLG; ovipositor sheaths protruding slightly beyond apex of Gt₇.

Etymology

Named after the collector of the holotype, the Swedish entomologist Anton Jansson, who collected insects mainly in the vicinities of the city Örebro (Närke Province), where he also lived and worked as a journalist.

Distribution

Sweden.

Host:

Unknown.

Notes

Holotype deposited in MZLU.