Abstract
The taxonomy of the myrmecophilous Maculinea alcon group (Lepidoptera: Lycaenidae) is highly debated. The host-plant and host-ant usage of these butterflies have conventionally been important in their identification. Maculinea ‘rebeli’ has generally been considered to be the xerophilous form of Ma. alcon (Ma. alcon X hereafter) with Gentiana cruciata as initial food plant. However, the type locality and all other known sites of Ma. rebeli are found above the coniferous zone, and are well separated from the lower regions where Ma. alcon X sites are found. Furthermore, no food plant and host ant data for the nominotypic Ma. rebeli have yet been published. Our aim was therefore to identify the host ant(s) of Ma. rebeli around the type locality and compare this with the host ant usage of nearby Ma. alcon X. Nests of Myrmica spp. (Hymenoptera: Formicidae) close to the host plants were opened on one Ma. alcon X (host plant: Gentiana cruciata) and two Ma. rebeli (host plant: Gentianella rhaetica, first record, confirmed by oviposition and emerging larvae) sites just before the flying period, to find prepupal larvae and pupae. Three Myrmica species (My. lobulicornis, My. ruginodis, My. sulcinodis) were found on the two Ma. rebeli sites, which parasitized exclusively My. sulcinodis (22 individuals in 7 nests). On the Ma. alcon X site Myrmica sabuleti and My. lonae were found, with My. sabuleti the exclusive host (51 individuals in 10 nests). Ichneumon cf. eumerus parasitized both butterflies. The results highlight the differentiation of Maculinea rebeli from Ma. alcon X, from both conservation biological and ecological points of view. Thus, it should be concluded that Ma. rebeli does not simply represent an individual form of Ma. alcon but it can be considered as at least an ecological form adapted to high mountain conditions both in its initial food plant and host ant species. In addition, it should be emphasized that Ma. alcon X (= Ma. rebeli auct. nec Hirschke) cannot be synonymised with Ma. rebeli (Hirschke, 1904).
Highlights
53 Myrmica nests were found on the three sites (Table 1), consisting of 52 nests of five Myrmica species and one empty but Maculinea-infested nest which was similar in appearance to nearby My. sabuleti nests
Nests of My. sabuleti and of the closely related (Radchenko and Elmes 2010) My. lonae Finzi, 1926 were found at the Ma. alcon X site (Sankt Ilgen), whereas the Myrmica composition of the two Ma. rebeli sites was totally different from this: My. ruginodis Nylander, 1846 and My. sulcinodis Nylander, 1846 were found at both sites, plus My. lobulicornis Nylander, 1857 at Präbichl
5 Ma. rebeli eggs on Gentianella rhaetica at Präbichl 6 Ma. rebeli pupae under a stone in a Myrmica lobulicornis nest at Zeiritz 7 Ma. alcon X pupae and a small larva found in Myrmica sabuleti nest at Sankt Ilgen, arrows sign infections with Ichneumon cf. eumerus
Summary
Maculinea van Eecke, 1915 (Lepidoptera, Lycaenidae) has been synonymised with Phengaris Doherty, 1890 (see: Fric et al 2007, Pech et al 2007, Kudrna and Fric 2013) we continue to use the well-established generic name here, since (i) the case is still undecided by the International Commission on Zoological Nomenclature (ICZN 2012) and strong arguments for the precedence of Maculinea over Phengaris have been made (Balletto et al 2010, and Comments on this Case); and (ii) Ugelvig et al (2011) have shown that Maculinea represents a monophyletic sub-clade and we agree with their conclusion: “We recommend that the nomenclatural debate is delayed until irrefutable evidence is provided”.Maculinea (abbreviated as “Ma.” below) butterflies are endangered species (Munguira and Martín 1999, Maes et al 2004, Settele et al 2005) and their larvae are social parasites of Myrmica Latreille, 1804 (Hymenoptera: Formicidae; abbreviated as “My.” below) ant colonies (Thomas et al 1989). Larvae of Maculinea alcon ([Denis & Schiffermüller], 1775) initially feed on the seeds of gentian plants for about a month and are later taken in and raised by Myrmica colonies (Thomas et al 1989) They have a “cuckoo” strategy, in which they mimic the odour (Thomas and Settele 2004, Nash et al 2008, Akino et al 1999) and sound (Barbero et al 2009) of the host ant species, and are fed like an ant larva (Thomas and Elmes 1998), they sometimes prey directly on the ant brood (Tartally 2004). The host ant and host plant usage of Ma. alcon has been thought to be important for taxonomic separation (Thomas et al 1989) of the hygrophilous (‘Ma. alcon H’ below) and the xerophilous (‘Ma. alcon X’) form of Ma. alcon, recent studies have been unable to show any consistent genetic separation between these two butterflies (Als et al 2004, Bereczki et al 2005, Ugelvig et al 2011)
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