Smart joints: auto-cleaning mechanism in the legs of beetles.

The auto-cleaning system in digging forelegs of the Congo rose chafer Pachnoda marginata femoro-tibial joint is described. The cleaning system consists of four subsystems: three external ones represented by microsetal pad, hairy brush and scraper and one internal one. They work proactively not only removing contaminants, but also preventing them from entering the joint. The principle of functioning of the cleaning system is based on the sliding of the contacting surfaces of the joint, equipped with hairs, bristles and scrapers. The mutual movement of such surfaces leads to the shift of contaminating particles and, ultimately, to their removal from surfaces of the joint. The key feature of the joint cleaning system is its complete autonomy, in which cleaning is performed constantly with each movement of the femoro-tibial joint without special actions required from the insect. The difference between the auto-cleaning system and self-cleaning and active grooming is also discussed.

Jumping mechanism in the marsh beetles (Coleoptera: Scirtidae).

The jumping mechanism with supporting morphology and kinematics is described in the marsh beetle Scirtes hemisphaericus (Coleoptera: Scirtidae). In marsh beetles, the jump is performed by the hind legs by the rapid extension of the hind tibia. The kinematic parameters of the jump are: 139-1536 m s-2 (acceleration), 0.4-1.9 m s-1 (velocity), 2.7-8.4 ms (time to take-off), 0.2-5.4 × 10-6 J (kinetic energy) and 14-156 (g-force). The power output of a jumping leg during the jumping movement is 3.5 × 103 to 9.6 × 103 W kg-1. A resilin-bearing elastic extensor ligament is considered to be the structure that accumulates the elastic strain energy. The functional model of the jumping involving an active latching mechanism is proposed. The latching mechanism is represented by the conical projection of the tibial flexor sclerite inserted into the corresponding socket of the tibial base. Unlocking is triggered by the contraction of flexor muscle pulling the tibial flexor sclerite backwards which in turn comes out of the socket. According to the kinematic parameters, the time of full extension of the hind tibia, and the value of the jumping leg power output, this jumping mechanism is supposed to be latch-mediated spring actuation using the contribution of elastically stored strain energy.

Insects use lubricants to minimize friction and wear in leg joints.

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.

Generic Review of New Zealand Chrysomelinae (Coleoptera: Chrysomelidae).

The leaf beetle subfamily Chrysomelinae is reviewed for New Zealand. The native fauna consists of six genera, three new, all of which are described: Aphilon Sharp, 1876; Caccomolpus Sharp, 1886; Chalcolampra Blanchard, 1853; Mauroda gen. nov.; Nanomela gen. nov.; Zeaphilon gen. nov.. Chalcolampra is the senior synonym of Cyrtonogetus Broun, 1915 (comb. nov.). These genera include 51 species, nine newly described and eight in new combinations, as follows: Caccomolpus laticollis (Broun, 1893) comb. nov., from Aphilon; C. pretiosus (Broun, 1880) comb. nov., from Aphilon; Chalcolampra crassa (Broun, 1915) comb. nov., from Cyrtonogetus; Maurodus arcus sp. nov.; M. cinctiger (Broun, 1921) comb. nov., from Caccomolpus; M. impressus (Broun, 1914) comb. nov., from Aphilon; M. lepidus sp. nov.; M. maculatus (Broun, 1893) comb. nov., from Caccomolpus; M. nunni sp. nov.; M. occiduus sp. nov.; M. ornatus (Broun, 1910) comb. nov., from Caccomolpus; M. owenensis sp. nov.; M. plagiatus (Sharp, 1886) comb. nov., from Caccomolpus; M. supernus sp. nov.; Nanomela tiniheke sp. nov.; Zeaphilon marskeae sp. nov.; Z. mirandum sp. nov.. All 11 species in the genus Maurodus are described and a key given for their identification. Type material of the New Zealand species of Aphilon (10 species), Caccomolpus (14 species) and Chalcolampra (13 species) is reviewed and lectotypes designated for 16 species, as well as M. cinctiger. A type species is designated for Caccomolpus: C. globosus Sharp, 1886. Holotypes are confirmed for 26 species. Seven genera and 13 species of exotic Chrysomelinae also occur in New Zealand and their presence is briefly reviewed. One of these exotics has been misnamed as Paropsisterna variicollis (Chapuis, 1877), a junior synonym of P. cloelia (Stål, 1860) (syn. nov.). A key to all genera of Chrysomelinae in New Zealand is provided.

Jumping mechanisms and performance in beetles. II. Weevils (Coleoptera: Curculionidae: Rhamphini).

We describe the kinematics and performance of the natural jump in the weevil Orchestes fagi (Fabricius, 1801) (Coleoptera: Curculionidae) and its jumping apparatus with underlying anatomy and functional morphology. In weevils, jumping is performed by the hind legs and involves the extension of the hind tibia. The principal structural elements of the jumping apparatus are (1) the femoro-tibial joint, (2) the metafemoral extensor tendon, (3) the extensor ligament, (4) the flexor ligament, (5) the tibial flexor sclerite and (6) the extensor and flexor muscles. The kinematic parameters of the jump (from minimum to maximum) are 530-1965 m s-2 (acceleration), 0.7-2.0 m s-1 (velocity), 1.5-3.0 ms (time to take-off), 0.3-4.4 µJ (kinetic energy) and 54-200 (g-force). The specific joint power as calculated for the femoro-tibial joint during the jumping movement is 0.97 W g-1. The full extension of the hind tibia during the jump was reached within up to 1.8-2.5 ms. The kinematic parameters, the specific joint power and the time for the full extension of the hind tibia suggest that the jump is performed via a catapult mechanism with an input of elastic strain energy. A resilin-bearing elastic extensor ligament that connects the extensor tendon and the tibial base is considered to be the structure that accumulates the elastic strain energy for the jump. According to our functional model, the extensor ligament is loaded by the contraction of the extensor muscle, while the co-contraction of the antagonistic extensor and flexor muscles prevents the early extension of the tibia. This is attributable to the leverage factors of the femoro-tibial joint providing a mechanical advantage for the flexor muscles over the extensor muscles in the fully flexed position. The release of the accumulated energy is performed by the rapid relaxation of the flexor muscles resulting in the fast extension of the hind tibia propelling the body into air.

The phylogeny of Galerucinae (Coleoptera: Chrysomelidae) and the performance of mitochondrial genomes in phylogenetic inference compared to nuclear rRNA genes.

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.

Jumping mechanisms and performance in beetles. I. Flea beetles (Coleoptera: Chrysomelidae: Alticini).

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(3)) m s(-2), velocity 1.48-2.80 m s(-1), time to take-off 1.35-2.25 ms, kinetic energy 2.43-16.5 µJ, G: -force 93-230. The jumping apparatus is localized in the hind legs and formed by the femur, tibia, femoro-tibial joint, modified metafemoral extensor tendon, extensor ligament, tibial flexor sclerite, and extensor and flexor muscles. The primary role of the metafemoral extensor tendon is seen in the formation of an increased attachment site for the extensor muscles. The rubber-like protein resilin was detected in the extensor ligament, i.e. a short, elastic element connecting the extensor tendon with the tibial base. The calculated specific joint power (max. 0.714 W g(-1)) 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.

First fossil Lamprosomatinae leaf beetles (Coleoptera: Chrysomelidae) with descriptions of new genera and species from Baltic amber.

In the current paper the first fossil representatives of leaf-beetles from the subfamily Lamprosomatinae (Coleoptera: Chrysomelidae) are described and illustrated from Upper Eocene Baltic amber: Succinoomorphus warchalowskii gen. et sp. nov., Archelamprosomius balticus gen. et sp. nov., and Archelamprosomius kirejtshuki sp. nov. A key to fossil Lamprosomatinae is provided.

Ivalia Jacoby--a flea beetle genus new to Australia (Coleoptera: Chrysomelidae: Galerucinae).

The genus Ivalia Jacoby, 1887 is recorded from Australia for the first time with descriptions of three new species, Ivalia reidi sp. nov., Ivalia iridescens sp. nov., and Ivalia lescheni sp. nov., from Queensland and New South Wales. A check-list of 66 species of Ivalia and a key to the Australian species are provided. New replacement names proposed are Ivalia samuelsoni nom. nov. for Ivalia bella (Samuelson, 1966), a secondary homonym of Ivalia bella (Chen, 1934) and Ivalia gruevi nom. nov. for Ivalia castanea (Gruev, 1985a), a secondary homonym of Ivalia castanea (Samuelson, 1966).

A second species of Psyllototus (Coleoptera: Chrysomelidae: Galerucinae).

Psyllototus doeberli sp. nov., a second species of the paleoendemic genus is described. This is the first named species of Alticini from the Upper Eocene Baltic amber of Yantarny, Kaliningrad region, Russia. A checklist of known Alticini from fossil resins is provided.