Research Article |
Corresponding author: Peter Huemer ( p.huemer@tiroler-landesmuseen.at ) Academic editor: Thibault Lachat
© 2021 Peter Huemer, Jürg Schmid.
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:
Huemer P, Schmid J (2021) Relict populations of Lyonetia ledi Wocke, 1859 (Lepidoptera, Lyonetiidae) from the Alps indicate postglacial host-plant shift to the famous Alpenrose (Rhododendron ferrugineum L.). Alpine Entomology 5: 101-106. https://doi.org/10.3897/alpento.5.76930
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Lyonetia ledi Wocke, 1859 (Lyonetiidae), was hitherto considered as a boreal species with a circumpolar distribution pattern and relict populations in isolated peat bogs north-east of the Alps (Austria, Czech Republic, Germany). In Europe it is known as a leaf-miner on Rhododendron tomentosum Stokes ex Harmaja (Ericaceae) as the primary host-plant and also Myrica gale L. (Myricaceae). The first record of L. ledi from the Swiss Alps on Rhododendron ferrugineum L., the famous Alpenrose, indicates an ancient host-plant switch during postglacial periods when R. tomentosum and R. ferrugineum shared habitat in the prealps. Conspecificity with northern populations is supported by the adult morphology and supplementing DNA barcodes (mtDNA COI gene). L. ledi is the first obligatory leaf-mining species on R. ferrugineum. Details of the life-history and habitat are described and figured. The record finally substantiates the probability of an autochthonous population in Carinthia (Austria), from where the species was recently published as new to the Alps.
Lyonetia ledi , new host-plant, new record, faunistics, Switzerland, boreo-montane, circumpolar, DNA barcoding
Although new national records are of considerable faunistic interest in Europe per se, they are often disregarded of only limited scientific value. Here we report an exceptional observation of a species of microlepidoptera which is not only of faunistic but also of considerable ecological interest as the first specialized leaf-miner on Rhododendron ferrugineum. The species discussed, Lyonetia ledi, was previously known in the Alps only from a single specimen from Carinthia, whose origin seemed questionable, especially because the known host-plants Rhododendron tomentosum (Ericaceae) and Myrica gale (Myricaceae) are absent from that area. On a visit to the Lower Engadine, Switzerland, on the 29th of July 2021 as part of the surveys for Biodiversity Monitoring Switzerland (Koordinationsstelle BDM 2014), occupied mines of an unidentified species were discovered on Rhododendron ferrugineum by PH and subsequently confirmed by JS. The find was immediately surprising, as no specialized leaf-miners were previously known from this plant (
A total of 19 male and 6 female specimens of Lyonetia ledi from Switzerland have been examined. Material is preserved in the research collection of Tiroler Landesmuseum Ferdinandeum (Hall, Austria) and of Jürg Schmid (Ilanz, Switzerland). Material is either pinned or alternatively set traditionally.
Species identification was based firstly on phenotypic characteristics of adults (wing markings, colour, size) using comparative collection specimens of L. ledi from the Tyrolean State Museums as well as on available online illustrations (
Tissue samples (a single hind leg) from 3 specimens of the suspected Lyonetia ledi were prepared according to prescribed standards to obtain DNA barcode sequences of a 658 base-pair long segment of the mitochondrial COI gene (cytochrome c oxidase subunit 1) and successfully processed at the Canadian Centre for DNA Barcoding (CCDB, Biodiversity Institute of Ontario, University of Guelph) using the standard high-throughput protocol described in
All sequences were submitted to GenBank, and further details including complete voucher data and images can be accessed in the public dataset “Lepidoptera of the Alps - Lyonetia ledi [DS-LYONLEDI]” https://doi.org/10.5883/DS-LYONLEDI in the Barcode of Life Data Systems BOLD (
The length of obtained DNA barcodes in three Swiss specimens of L. ledi was 586, 632 and 658 bp respectively. A considerable intraspecific divergence was detected in DNA barcodes of L. ledi (Fig.
However, apart from exceptions, DNA barcode distances to nearest neighbours are much higher than intraspecific divergence in European Lyonetia ranging from c. 6% to 12% (Table
Intra- and interspecific divergence in the studied Lyonetia species (%).
Species | Mean Intra-Sp | Max Intra-Sp | Nearest Species | Distance to NN |
---|---|---|---|---|
Lyonetia clerkella | 2.69 | 5.49 | Lyonetia ledi | 12.13 |
Lyonetia ledi | 1.68 | 6.65 | Lyonetia pulverulentella | 8.76 |
Lyonetia padifoliella | 0.43 | 0.79 | Lyonetia prunifoliella | 5.75 |
Lyonetia prunifoliella | 0.16 | 0.17 | Lyonetia padifoliella | 5.75 |
Lyonetia pulverulentella | 0.54 | 1.2 | Lyonetia ledi | 8.76 |
Material examined. 1♂: Switzerland, Graubünden, Ardez, SE Sur En, 1760 m, 46°45'38"N, 10°11'11.7"E, 6.8.2021 ex larva (Rhododendron ferrugineum), leg. Huemer; 3♂: same data, but DNA Barcode TLMF 30911, DNA Barcode TLMF 30912, DNA Barcode TLMF 30913; 4♂: same data, but 21.8.2021 ex pupae, all leg Huemer coll. TLMF. 11♂, 6♀ same locality, 8.2021 e.l., e.p. leg. et coll. JS.
Adult (Figs
For exhaustive description of the adults including genitalia of both sexes see
Biology. In Europe, Lyonetia ledi is a widespread leaf-miner of Rhododendron tomentosum (Ericaceae), but in the northern part of the continent it is also regularly recorded from the unrelated Myrica gale (Myricaceae), a species absent from large parts of Central Europe. Larvae of the newly discovered population from the Engadine mine the leaves of R. ferrugineum. The egg is laid on the upper side of a leaf. The tunnel-mine initially extends towards the base of the leaf, then turns and continues alongside the leaf rim towards the leaf tip, where a spacious blotch mine is formed. Only current year leaves, recognizable by their green underside are infested, while older leaves with the plant's name-giving rusty underside may contain mines from previous years only (Figs
The larvae seem to be regularly infested by parasitic wasps of Diadegma cf. semiclausum, (Ichmeumonidae) (barcoded) and an unidentified species of Ichneumonidae as we found a number of their cocoons that were already empty.
Habitat (Fig.
In Europe, Lyonetia ledi is a leaf-miner mainly of Rhododendron tomentosum (formerly Ledum palustre) (Ericaceae), whereas in Asia it has also been recorded from R. dauricum L., R. indicum (L.) Sweet, R. kaempferi Planch., R. mucronulatum Turcz., R. occidentale Torr. & A. Gray, R. japonicum (A. Gray) Suringar and R. pentandrum (Maxim.) Craven and in North America from R. albiflorum Hook. (
A unique record of L. ledi from the southern Alps in the absence of one of the known host-plants remained unexplained (
The authors would like to thank Marko Mutanen, University of Oulu, Peter Schönswetter, University of Innsbruck, Michael Thalinger, Tiroler Landesmuseen, Innsbruck, and Christian Wieser, Landesmuseum Kärnten, Klagenfurt for valuable information. We furthermore acknowledge the valuable input of the reviewers Natalia Kirichenko (Sukachev Institute of Forest SB RAS, Krasnoyarsk, Russia) and Marko Mutanen (University of Oulu, Finland). Paul D.N. Hebert and the entire team at the Canadian Centre for DNA Barcoding (Guelph, Canada) are acknowledged for continuous support with sequencing work. The study was furthermore supported by the Promotion of Educational Policies, University and Research Department of the Autonomous Province of Bolzano – South Tyrol with funds for the projects “Genetische Artabgrenzung ausgewählter arktoalpiner und boreomontaner Tiere Südtirols”. Last but not least Robert J. Heckford (Plympton, U.K.) is thanked for his careful language proofreading with valuable comments.