© Entomologica Fennica. 1 June 2018 Occurrence and biology of Pseudogonalos hahnii (Spinola, 1840) (Hymenoptera: Trigonalidae) in Fennoscandia and the Baltic states Simo Väänänen, Juho Paukkunen, Villu Soon & Eduardas Budrys Väänänen, S., Paukkunen, J., Soon, V. & Budrys, E. 2018: Occurrence and bio- logy of Pseudogonalos hahnii (Spinola, 1840) (Hymenoptera: Trigonalidae) in Fennoscandia and the Baltic states. Entomol. Fennica 29: 8696. Pseudogonalos hahnii is the only known species of Trigonalidae in Europe. It is a hyperparasitoid of lepidopteran larvae via ichneumonid primary parasitoids. Possibly, it has also been reared from a symphytan larva. We report the species for the first time from Estonia, Lithuania and Russian Fennoscandia, and list all known observations from Finland and Latvia. An overview of the biology of the species is presented with a list of all known host records. S. Väänänen, Vantaa, Finland; E-mail: [email protected] J. Paukkunen, Finnish Museum of Natural History, Zoology Unit, P.O. Box 17, FI-00014 University of Helsinki, Finland; E-mail: [email protected] V. Soon, Natural History Museum, University of Tartu, Vanemuise 46, 51014 Tartu, Estonia; E-mail: [email protected] E. Budrys, Nature Research Centre, Akademijos 2, LT-08412 Vilnius, Lithuania; E-mail: [email protected] Received 27 June 2017, accepted 22 September 2017 1. Introduction ovipositor with Aculeata (Weinstein & Austin 1991). The trigonalid ovipositor is reduced and Trigonalidae is a moderately small family of par- hidden within the abdomen and it is not known if asitic wasps of little over 100 species and about it is used in egg placement (Quicke et al. 1999). 20 genera (Carmean & Kimsey 1998, Chen et al. In the past, Trigonalidae have been variously 2014). They are mainly found in the tropics and placed within or near almost all other apocritan subtropics (Carmean & Kimsey 1998). Five spe- lineages (Carmean & Kimsey 1998) and they cies have been described from the Nearctic have been considered to be phylogenetically (Smith & Stocks 2005) and around two dozen close to Evanioidea, Megalyroidea, Ceraphro- species from the Palaearctic (Lelej 2003, Chen et noidea or Aculeata (Sharkey 2007, Klopfstein et al. 2014). Only one species occurs in Europe al. 2013). Evidence, both morphological and mo- (Madl 2013). Trigonalidae clearly belong to lecular, is mountingthat Trigonalidaeare closely Parasitica, but morphologically they possess related to stinging wasps (Aculeata) and Evani- some features that are reminiscent of Aculeata oidea (Klopfstein et al. 2013, Zimmermann & and Symphyta. For example, head shape, mouth- Vilhelmsen 2016, Branstetter et al. 2017, Peters parts and tarsal plantulae are shared with Sym- et al. 2017). Trigonalidae is also closely related to phyta and general body shape and terminal the extinct Cretaceous family Maimetshidae ENTOMOL. FENNICA Vol. 29 • P. hahnii in Fennoscandia and the Baltic 87 (Vilhelmsen et al. 2010, Perrichot et al. 2011) to cut through the host cocoon, pupa or puparium which is currently also placed in superfamily (Weinstein & Austin 1991). Some Trigonalidae Trigonaloidea (Aguiar et al. 2013). Asymmetri- species depend on their eggs being brought with cal mandibles (not present in all maimetshids) phytophagous larvae into nests of social vespids, and female tarsal plantulae unite these two fami- where they develop as primary parasitoids of lies, but maimetshids differ from Trigonalidae by vespid larvae (Weinstein & Austin 1991). In ad- their exserted ovipositor and missingantennal dition to Trigonalidae, only a few Hymenoptera tyloids (Vilhelmsen et al. 2010, Perrichot et al. groups (Eucharitidae, Perilampidae, Ichneu- 2011). The oldest fossils of true Trigonalidae are monidae: Eucerotinae) oviposit their eggs away known from French Albian Amber (100 to 113 from hosts but these groups have planidial larvae, mya) (Nel et al. 2003). i.e. larvae that actively seek and enter the host ani- Almost all trigonalid species are hyper- mal (Heraty & Murray 2013, Shaw 2014). Like- parasitoids, attackingIchneumonidae (Hyme - wise, some elampine cuckoo wasps (Hymenopte- noptera) and Tachninidae (Diptera) (referred in ra: Chrysididae) oviposit into free-livingaphids this paper as primary hosts) that parasitize leaf- and depend on digger wasp (Hymenoptera: feedinglepidopteran or symphytan larvae (re - Crabronidae) females to prey on and carry these ferred in this paper as secondary hosts). Two aphids into their nests, wherein the elampine lar- Australian species develop as primary parasitoids vae develop as parasitoids on crabronid progeny of sawflies (Weinstein & Austin 1991). One (Winterhagen 2015). trigonalid species has been reared from a tachinid Pseudogonalos Schulz, 1906 is a palaearctic developingon a detrivorous crane fly (Diptera: genus that includes three valid species: Pseudo- Tipulidae) larva (Gelhaus 1987). Trigonalid fe- gonalos hahnii (Spinola, 1840), P. harmandi males are very fecund and oviposit thousands of Schulz, 1906 and P. angusta Chen, van Achter- eggs along or within the margins of plant leaves. berg, He & Xu, 2014 (Carmean & Kimsey 1998, The eggs in turn are by chance ingested by lepi- Chen et al. 2014). Only a single and now lost P. dopteran or symphytan larvae (Carmean 1991, harmandi specimen is known from Darjeeling, Weinstein & Austin 1991). The eggs have never North-Eastern India (Carmean & Kimsey 1998). been observed to have been purposefully ovipos- Recently, Chen et al. (2014) described a third ited near host animals (Schnee 2011). Among Pseudogonalos species from China (Inner Mon- parasitoids, only some tachinid flies are known to golia), P. angusta Chen, van Achterberg, He & depend on this same method of host ingestion to Xu, 2014. Pseudogonalos hahnii is a widespread reach their hosts (Stireman et al. 2006). Mechani- but rare palaearctic species, and it is the only Eu- cal and chemical stimuli incite the 1st instar ropean species of the family (Lelej 2003, Schnee trigonalid larva to hatch and it bores through the 2011). secondary host larvas gut wall to search for a pri- Pseudogonalos hahnii is a black species with mary ichneumonid or tachinid parasitoid larva dark spotted fore wings. The habitus (Fig. 1) is present within the secondary larvas hemocoel, reminiscent of some aculeate wasps, e.g. a pem- after which it develops as a hyperparasitoid phredine sphecid. It can be separated from the (Weinstein & Austin 1991). Trigonalid larval de- other hymenopterans in the region by the combi- velopment is then delayed until the ichneumonid nation of various characters: characteristic fore or tachinid primary host pupates or is near pupa- wingvenation with 10 developed cells and well- tion, after which the trigonalid larva consumes developed costal cell, hind wingwith 2 cells, the primary host. The first three trigonalid larval raised crests near the point of antennal insertions instars are endoparasitic while the fourth and fifth on the middle of the face, antennae with 2627 instars are ectoparasitic after which pupation segments, mandibles with 35 large teeth, pres- takes place. The third instar has a heavily chiti- ence of tarsal plantar lobes on tarsal segments and nized head and formidable mandibles, suggesting cleft tarsal claws (Gauld & Bolton 1988, Chen et that it uses them to fight and kill other possible al. 2014). parasitoid larvae it encounters within the host. In this article, we review the biology and After eclosion, the adult uses its strongmandibles distribution of the only European trigonalid spe- 88 Väänänen et al. • ENTOMOL. FENNICA Vol. 29 Private collection of Reima Leinonen and Guy Söderman (Coll. Leinonen & Söderman) Private collection of Veli Vikberg(Coll. Vik - berg) Two Finnish specimens were DNA barcoded by the Canadian Centre for DNA barcoding(CCDB) and their DNA barcode sequences were depos- ited in the BOLD systems database. They are available from GenBank through the accession numbers MF040884 and MF04088 (Digital Ob- ject Identifier (DOI): dx.doi.org/10.5883/DS- PSEHAH) There has been some dispute about the correct spelling of the family (Trigonalidae vs. Trigo- nalyidae) and superfamily (Trigonaloidea vs. Trigonalyoidea) names. We follow Carmean and Kimsey (1998) and use Trigonalidae as done recently by Aguiar et al. (2013), Madl (2013) and Fig. 1. Habitus of Pseudogonalos hahnii. Specimen Broad (2016). For differingopinions, see Lelej collected from Parikkala, Finland. Photo: Pekka (2003) and Chen et al. (2014). For nomenclature Malinen. of host species, we follow Fauna Europaea (de Jong et al. 2014). cies P. hahnii in Fennoscandia and the Baltic states. 3. Results 2. Materials and methods Synonymy and records of Pseudogonalos hahnii from Fennoscandia and the Baltic states are pre- We compiled all published records of Pseudo- sented below. The records are listed in chrono- gonalos hahnii from the study region and gath- logical order within countries, and the acronyms ered data from the followingpublic and private in parentheses refer to specimen depositories. collections: Coordinates are given in the WGS84 system. The symbol ~ indicates that the coordinates were esti- Institute of Agricultural and Environmental Sci- mated from the locality name. ences, Estonian University of Life Sciences [former Institute of Zoology and Botany], Pseudogonalos hahnii (Spinola, 1840) Tartu, Estonia (IZBE) Trigonalys hahnii Spinola, 1840 Entomological collection of the Nature Research Trigonalis anglicana Shuckard, 1841 Centre, Vilnius, Lithuania (NRC) Trigonalis