Revision of first instar larvae ofMeloe, subgeneraEurymeloeandCoelomeloe, with new descriptions and a key to the species (Coleoptera: Meloidae)

Abstract

In this paper the larval morphology of the Palaearctic Meloe subgenera Eurymeloe and Coelomeloe is revised. We describe the first instar larva of Meloe (Eurymeloe) apenninicus, endemic to the Italian peninsula and, comparatively, triungulins of three more species of the subgenus Eurymeloe: M. apivorus, M. ganglbaueri, misidentified in literature, and of M. mediterraneus, incompletely described. Descriptions are accompanied by scanning electron microscope (SEM) photos of diagnostic characters and by a table reporting the size of the morphological details of 11 Euro-Mediterranean species and of M. (Coelomeloe) tuccius. The taxonomic position of the subgenus Coelomeloe and its distinction from Eurymeloe are discussed on the basis of larval morphology. Taxonomical problems concerning some Eurymeloe species are also discussed. A key to first instar larvae of all known Eurymeloe and Coelomeloe triungulins is provided.

Phylogeny of Meloini blister beetles (Coleoptera, Meloidae) and patterns of island colonization in the Western Palaearctic

“…Third, Eurymeloe (type species: Meloe brevicollis Panzer, 1793, by subsequent designation of Pinto & Selander, 1970) now includes all species formerly placed in the subgenera Eurymeloe and Coleomeloe (type species: Meloe tuccia Rossi, 1790, by monotypy). The high support recovered in our phylogenetic hypothesis for the inclusion of E. tuccia within Eurymeloe (see Figure 1) agrees with morphological hypotheses depicting a close relationship between these two taxa (Bologna, 2020b; Di Giulio et al., 2013; Selander, 1985).…”

“…Our molecular phylogenetic hypothesis, in which Mesomeloe is a sister taxon to Eurymeloe , is congruent with the inferences made from larval morphology (Di Giulio et al., 2002). First‐instar larvae of Coelomeloe ( E. tuccia ) and of the M. brevicollis group of Eurymeloe (sensu Bologna, 1988) share a clearly protruding mesothoracic spiracle and a large transverse abdominal spiracle I (Di Giulio et al., 2013). As these taxa were not treated as reciprocally monophyletic, this similarity was thought to be due to parallel evolution (homoplasy) (Di Giulio et al., 2013).…”

“…First‐instar larvae of Coelomeloe ( E. tuccia ) and of the M. brevicollis group of Eurymeloe (sensu Bologna, 1988) share a clearly protruding mesothoracic spiracle and a large transverse abdominal spiracle I (Di Giulio et al., 2013). As these taxa were not treated as reciprocally monophyletic, this similarity was thought to be due to parallel evolution (homoplasy) (Di Giulio et al., 2013). However, our phylogeny supports the monophyly of Coelomeloe and the M. brevicollis group (see Figure 1), making this feature a synapomorphy and a useful character for the diagnosis of this clade.…”

“…Eurymeloe fernandezi split from its sister lineage during the Middle Miocene (mean = 17.1, 95 HDP = 11.20–24.96 Mya), coinciding with the emergence of the oldest island of the Canary Archipelago at about 20 Ma (Juan et al., 2000). Many Atlantic species of Eurymeloe , including both Macaronesian and continental ones, such as E. gomari , E. baamarani (Ruiz & García‐París, 2015), E. pallidicolor (Martínez de la Escalera, 1909) and E. apivorus , have a narrow geographic distribution (Bologna, 1988, 1991, 2020a; Ruiz & García‐París, 2009, 2015; Di Giulio et al., 2013). The narrow geographic ranges of these phoretic species contrast with those of the widely distributed species E. tuccia, E. mediterraneus and M. proscarabaeus .…”

“…It also changes the phylogenetic placement of some taxa. Consequently, some previous hypotheses on character evolution and homoplasy in the group need to be reinterpreted, particularly those regarding the morphological traits of first‐instar larvae, which have been widely used to support or reject evolutionary groups within Meloini (Bologna, 1988, 1991; Bologna et al., 1989, 1990; Bologna & Pinto, 2001; Di Giulio et al., 2002, 2013, 2014; Pinto & Bologna, 1993; Selander, 1989).…”