Timarcha

Abstract: We conducted a 3-yr field experiment that manipulated the presence of ungulates (domestic sheep and Spanish ibex Capra pyrenaica, Bovidae) and the monophagous beetle Timarcha lugens (Chrysomelidae) to evaluate (1) the effects on beetle abundance and interaction with the woody crucifer Hormathophylla spinosa; (2) the reciprocal effect of this insect on the interaction between ungulates and the plant; (3) their impact on H. spinosa reproductive output; and (4) the abundance of an associated taxon, Ceutorhynchus sp. nov. (Curculionidae). Our experiment showed that ungulate exclusion increased Timarcha abundance, whereas Timarcha had no effect on ungulates. H. spinosa reproductive output increased threefold promptly when ungulates were excluded, although in the third year Timarcha began to have effects on shrub reproduction. Ungulates affected weevils both by exploitative competition and by incidental predation, with the total number of weevils emerging per shrub being more than fourfold higher in shrubs excl...

Abstract: The high-level classification of Chrysomelidae (leaf beetles) currently recognizes 12 or 13 well-established subfamilies, but the phylogenetic relationships among them remain ambiguous. Full mitochondrial genomes were newly generated for 27 taxa and combined with existing GenBank data to provide a dataset of 108 mitochondrial genomes covering all subfamilies. Phylogenetic analysis under maximum likelihood and Bayesian inference recovered the monophyly of all subfamilies, except that Timarcha was split from Chrysomelinae in some analyses. Three previously recognized major clades of Chrysomelidae were broadly supported: the ‘chrysomeline’ clade consisting of (Chrysomelinae (Galerucinae + Alticinae)); the ‘sagrine’ clade with internal relationships of ((Bruchinae + Sagrinae) + (Criocerinae + Donaciinae)), and the ‘eumolpine’ clade comprising (Spilopyrinae (Cassidinae (Eumolpinae (Cryptocephalinae + Lamprosomatinae)))). Relationships among these clades differed between data treatments and phylogenetic algorithms, and were complicated by two additional deep lineages, Timarcha and Synetinae. Various topological tests favoured the PhyloBayes software as the preferred inference method, resulting in the arrangement of (chrysomelines (eumolpines + sagrines)), with Timarcha placed as sister to the chrysomeline clade and Synetinae as a deep lineage splitting near the base. Whereas mitogenomes provide a solid framework for the phylogeny of Chrysomelidae, the basal relationships do not agree with the topology of existing molecular studies and remain one of the most difficult problems of Chrysomelidae phylogenetics.

Abstract: Historically the taxonomy of the genus Timarcha has been, and continues to be, quite confusing and largely erroneous. The confusion is mainly due to the absence of reliable traits that aid in precise identification; the lack of study of types at species-level has also contributed to the difficulty in the taxonomy. To improve this situation, we propose techniques for the dissection and study of three useful diagnostic characters such as the vestiture of the sole of female tarsi, and the morphology of the endophallus and its sclerites in males. These features combined are distinctive for each of the species and can help to resolve the taxonomy of the genus.