Abstract
The flightless Entiminae weevil genus Laparocerus is the species-richest genus, with 237 species and subspecies, inhabiting Macaronesia (Madeira archipelago, Selvagens, Canary Islands) and the continental ‘Macaronesian enclave’ in Morocco (one single polytypic species). This is the second contribution to gain insight of the genus and assist in its systematic revision with a mitochondrial phylogenetic analysis. It centres on the Canarian clade, adding the 12S rRNA gene to the combined set of COII and 16S rRNA used in our first contribution on the Madeiran clade (here re-analysed). The nuclear 28S rRNA was also used to produce an additional 4-gene tree to check coherency with the 3-gene tree.A total of 225 taxa (95%) has been sequenced, mostly one individual per taxa. Plausible explanations for incoherent data (mitochondrial introgressions, admixture, incomplete lineage sorting, etc.) are discussed for each of the monophyletic subclades that are coincident with established subgenera, or are restructured or newly described. The overall mean genetic divergence (p-distance) among species is 8.2%; the mean divergence within groups (subgenera) ranks from 2.9 to 7.0% (average 4.6%), and between groups, from 5.4% to 12.0% (average 9.2%). A trustful radiation event within a young island (1.72 Ma) was used to calibrate and produce a chronogram using the software RelTime.These results confirm the monophyly of both the Madeiran (36 species and subspecies) and the Canarian (196 species and subspecies) clades, which originated ca. 11.2 Ma ago, and started to radiate in their respective archipelagos ca. 8.5 and 7.7 Ma ago. The Madeiran clade seems to have begun in Porto Santo, and from there it jumped to the Desertas and to Madeira, with additional radiations. The Canarian clade shows a sequential star-shape radiation process generating subclades with a clear shift from East to West in coherence with the decreasing age of the islands. Laparocerus garretai from the Selvagens belongs to a Canarian subclade, and Laparocerus susicus from Morocco does not represent the ancestral continental lineage, but a back-colonisation from the Canaries to Africa. Dispersal processes, colonisation patterns, and ecological remarks are amply discussed. Diversification has been adaptive as well as non-adaptive, and the role of ’geological turbulence’ is highlighted as one of the principal drivers of intra-island allopatric speciation.Based on the phylogenetic results, morphological features and distribution, five new monophyletic subgenera are described: Aridotrox subg. n., Belicarius subg. n., Bencomius subg. n., Canariotrox subg. n., and Purpuranius subg. n., totalling twenty subgenera in Laparocerus.
Highlights
Laparocerus Schönherr, 1834 are flightless Entimine weevils with free-living edaphic larvae, and most are oligophagous and climb vegetation to feed upon the leaves (Machado 2003)
Xia’s index for substitution saturation in COII produced values of 0.074 and 0.46 which were significantly lower than the critical value for symmetric topologies (0.69–0.78, P < 0.001; 0.69–0.77, P < 0.001 respectively), suggesting that sites have reached little saturation and sequences can be reliably used for phylogenetic reconstruction
Species presently attributed to the genus Laparocerus form two monophyletic clades that originated ca. 11.2 Ma ago: the Madeiran clade (TMRCA 8.5 Ma) and the Canarian clade (TMRCA 7.7 Ma)
Summary
Laparocerus Schönherr, 1834 are flightless Entimine weevils with free-living edaphic larvae, and most are oligophagous and climb vegetation to feed upon the leaves (Machado 2003). All species are endemic to the oceanic islands of Macaronesia (Madeira, Selvagens, and Canary Islands), with the exception of one polytypic species, endemic to west Morocco, on the mainland. They are not known from the Cape Verde Islands, while the species from the Azores originally attributed to Laparocerus as subgenus Drouetius Méquignon, 1942 represent a separate Azorean endemic and rather distant genus (Machado 2009a). The external morphological disparity within this Entimine lineage is extraordinary and explains why several species groups were originally attributed to other genera (e.g. Omias Germar, 1826) or established as separate genera: Atlantis Wollaston, 1854, Cyphoscelis Wollaston, 1864, Lichenophagus Wollaston, 1854 or Anillobius Fauvel, 1907. In addition to its restricted distribution, there are only a few shared features that characterise the species of this group: (a) the presence of a spiculum relictum in the post-tegminal membrane representing the VIII male sternite (Fig. 1M), (b) the insertion of the seminal duct at a secondary poach (gonoporal diverticulum) of the internal sac of the aedeagus, which detaches either laterally or from the tip of the internal sac (Fig. 1K–L), (c) the metanepisternum narrow and basally protruding over the outer angle of the metacoxa hiding its contact with the elytral margin, and (d) the elytral declivity not overhanging the abdominal apex
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