With efficient sequencing techniques, full mitochondrial genomes are rapidly replacing other widely used markers, such as the nuclear rRNA genes, for phylogenetic analysis but their power to resolve deep levels of the tree remains controversial. We studied phylogenetic relationships of leaf beetles (Chrysomelidae) in the tribes Galerucini and Alticini (root worms and flea beetles) based on full mitochondrial genomes (103 newly sequenced), and compared their performance to the widely sequenced nuclear rRNA genes (full 18S, partial 28S). Our results show that: (i) the mitogenome is phylogenetically informative from subtribe to family level, and the per‐nucleotide contribution to nodal support is higher than that of rRNA genes, (ii) the Galerucini and Alticini are reciprocally monophyletic sister groups, if the classification is adjusted to accommodate several ‘problematic genera’ that do not fit the dichotomy of lineages based on the presence (Alticini) or absence (Galerucini) of the jumping apparatus, and (iii) the phylogenetic results suggest a new classification system of Galerucini with eight subtribes: Oidina, Galerucina, Hylaspina, Metacyclina, Luperina, Aulacophorina, Diabroticina and Monoleptina.

The present study analyses the anatomy, mechanics and functional morphology of the jumping apparatus, the performance and the kinematics of the natural jump of flea beetles (Coleoptera: Chrysomelidae: Galerucinae: Alticini). The kinematic parameters of the initial phase of the jump were calculated for five species from five genera (average values from minimum to maximum): acceleration 0.91-2.25 (×10 ) of the femoro-tibial joint during the jumping movement and the fast full extension of the hind tibia (1-3 ms) suggest that jumping is performed via a catapult mechanism releasing energy that has beforehand been stored in the extensor ligament during its stretching by the extensor muscles. In addition, the morphology of the femoro-tibial joint suggests that the co-contraction of the flexor and the extensor muscles in the femur of the jumping leg is involved in this process.

A protein-based lubricating substance is discovered in the femoro-tibial joint of the darkling beetle Zophobas morio (Insecta). The substance extrudes to the contacting areas within the joint and appears in a form of filiform flows and short cylindrical fragments. The extruded lubricating substance effectively reduces the coefficient of sliding friction to the value of 0.13 in the tribosystem glass/lubricant/glass . This value is significantly lower than 0.35 in the control tribosystem glass/glass and comparable to the value of 0.14 for the tribosystem glass/dry PTFE (polytetrafluoroethylene or Teflon). The study shows for the first time that the friction-reducing mechanism found in Z. morio femoro-tibial joints is based on the lubricant spreading over the contacting surfaces rolling or moving at low loads and deforming at higher loads, preventing direct contact of joint counterparts. Besides Z. morio , the lubricant has been found in the leg joints of the Argentinian wood roach Blaptica dubia .

Femoro-tibial leg joint, head-prothorax joint (gular area) and occipital region of the head were examined using scanning electron microscopy in insects from the orders Blattodea and Coleoptera. Lubricating substances and corresponding pore openings were found in Argentinean Wood Roach Blaptica dubia and in the beetles from families Carabidae, Hydrophilidae, Silphidae, Scarabaeidae, Elateridae, Tenebrionidae and Curculionidae. Lubricant on the contacting surfaces were found on femoral and tibial counterparts of leg joints of different beetle species and cockroaches, in the gular region of the head in beetles, and in the occipital region of the head of the cockroach. Typical pore opening was on an average 1 µm in diameter (ranging from 0.5 µm to 10.0 µm). The amount of pore openings in a joint varies from a few pores to hundreds. The lubricant is found to be strongly variable in its appearance usually in the form of a single elongated filiform flow, as well as long or short drops, often forming accumulations or spreading over the surface. The supposed function of the lubricant in studied joints is discussed and assumed as friction and wear minimization. The presence of a high amount of the lubricant in leg joints of insects with intense leg locomotion is presumed.

Leaf beetles Chrysomelidae of Rovno amber, from the Late Eocene, are recorded and described. Chrysomelidae of Rovno amber are represented by three subfamilies: Galerucinae (Alticini), Chrysomelinae, and Eumolpinae. Two new genera and three new species of Alticini: Manobiomorpha Nadein, gen. nov. (type species Manobiomorpha eocenica Nadein, sp. nov.), Psyllototus Nadein, gen. nov. (type species Psyllototus progenitor Nadein, sp. nov.), and Crepidodera decolorata Nadein et Perkovsky, sp. nov. are described. A new chrysomeline genus and species Paleophaedon minutus Nadein gen. nov. et sp. nov. is described. Probable trophic association of Crepidodera decolorata sp. nov., the taxonomic positions of Manobiomorpha gen. nov. and Psyllototus gen. nov., and the composition of leaf beetle faunas of Middle and Late Eocene of Europe are discussed.