Sibling species in theChrysis ignitacomplex: molecular, morphological and trophic differentiation ofBaltic species, with a description of two new cryptic species (Hymenoptera:Chrysididae)

Abstract

Cryptic species complexes cause major challenges for taxonomists and alter understanding of species diversity. In Northern Europe, the Chrysis ignita species group is one such complex with numerous sympatric sibling species. The objective of this paper is to assess the taxonomy of 15 species from this group using three different approaches: molecular, morphological and trophic differentiation. The analysed set of molecular markers included a 7400‐bp‐long sequence of the mitochondrial genome covering complete sequences of CO1, CO2, ATP8, ATP6, CO3, ND3, 16S and 12S rRNA, nine tRNAs and a partial sequence of CytB, as well as a 3880‐bp‐long sequence of the nuclear DNA covering a part of 18S rRNA, the ITS1, 5.8S rRNA, ITS2 and a part of 28S rRNA. Discrete diagnostic characters of each species sequence were retrieved using the Characteristic Attribute Organisation System algorithm and a molecular identification key was compiled. The study revealed a higher evolutionary rate of the genes ATP8, ATP6, CO3, ND3 and CytB compared to that of CO1, CO2 and 16S; the studied nuclear markers demonstrated a lower evolutionary rate than the mitochondrial markers. A consensus tree compiled based on the combined mtDNA and nuclear markers with a strongly supported topology resolved the position of the C. schencki – C. parietis sp.n. clade as sister to the C. ignita – C. impressa clade and supported the monophyly of the C. angustula – C. longula clade. We compiled a morphometric species identification key applying linear discriminant equations. The trophic differentiation was assessed using data on host preferences of ten Chrysis species reared from trap‐nests; the analysis demonstrated that most of them are specialists exploiting a single or a few taxonomically related host species. In most cases, all three approaches supported the distinct status of the included species. Moreover, two previously undescribed species were consistently supported by the molecular methods. Therefore, we describe these as new, namely C. horridula sp.n. and C. parietis sp.n. Only C. mediata and C. solida were not clearly distinguished using the molecular phylogeny reconstruction methods. However, based on distinctive niche divergence, the presence of molecular characters and morphometric differences, we consider them as phylogenetically young but distinct species. In view of the weak morphological and molecular differentiation, the widely overlapping distribution areas and often similar habitat preferences and the trophic specialization, the C. ignita complex presents a possible model for studies of sympatric cryptic speciation. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:1EBAF0E1-5FB7-4CF4-A595-C11982448360.

The Palaearctic types of Chrysididae (Insecta, Hymenoptera) deposited in the Hungarian Natural History Museum, Budapest

“…West Palaearctic Chrysididae are well known (Linsenmaier 1999;Rosa & Soon 2012), but still some problems related to the interpretation of the oldest types are found (Rosa et al 2015c). The new frontier for European chrysidid is the molecular systematic study, which already helped in the identification of new species (Paukkunen et al 2015;Orlovskytė et al 2016), separation of subspecies raised to species rank (Soon & Sarma 2011) and will clarify the systematic placement of several taxa still considered as subspecies by Linsenmaier (1959aLinsenmaier ( , 1959bLinsenmaier ( , 1987Linsenmaier ( , 1987Linsenmaier ( , 1997Linsenmaier ( , 1999 (Mitroiu et al 2015). On the other hand, Chrysididae from East Palaearctic are less known.…”

Trap nests for bees and wasps to analyse trophic interactions in changing environments—A systematic overview and user guide

“…Additionally, the nest structure and many other aspects of species’ individual life histories were discovered, which broadened the understanding of the general biology of those species and would have otherwise stayed obscure (e.g., Aguiar & Garófalo, ; Clement & Rust, ). Several new species were described from specimens collected with trap nests (e.g., Orlovskyte, Budrys, Budriene, Radzeviciute, & Soon, ; Parker, ). Along with the new species descriptions, an integrative picture of life histories was possible, including surprising and remarkable discoveries (e.g., Staab, Ohl, Zhu, & Klein, ).…”

“…While generalist parasitoids, such as Melittobia spp. are sometimes present (e.g., Pereira‐Peixoto, Pufal, Staab, Martins, & Klein, ; Tylianakis et al., ), most parasitoids are host‐specific and only attack a single or a few closely related species at a given locality (e.g., Orlovskyte et al., ; Staab et al., ). In addition to the trophic interactions with pollen, prey and parasitoids, less well‐known interaction types were also studied with trap nests, including the plant species that leaf‐cutting bees exploit for nest construction (e.g., Torretta, Durante, Colombo, & Mabel Basilio, ) or the oil sources of neotropical oil‐collecting bees (e.g., Carvalho, Carreira, Rego, & Albuquerque, ).…”

“…Several new species were described from specimens collected with trap nests (e.g., Orlovskyte, Budrys, Budriene, Radzeviciute, & Soon, 2016;Parker, 1976…”

Species delimitation in the crypsis‐defended and polymorphic stick insects of the genusLibethra(Phasmatodea, Diapheromeridae)

“…Lumley & Sperling ; Schütte & Stüben ; Monckton ; Orlovskyt≐ et al . ).Tissue samples (legs) were obtained from all collected specimens and preserved in ethanol at 4 °C. The genomic DNA was extracted using the protocol of DNeasy blood and tissue kit (QIAGEN, Hilden, Germany).…”