Background Springtails (Hexapoda: Collembola) are tiny organisms that lead a hidden life, mostly occuring deep in the soil and on leaf litter. They have a variety of interesting body morphology patterns, the most famous of which is the catapult-like structure that enables them to jump and flee from predators. This highly specialized jumping apparatus consists of a mobile furca, which when at rest fits into a trigger, "the retinaculum" on the ventral side of the abdomen. Despite the many studies that have attempted to investigate the jumping apparatus, the actual mechanisms involved in the jump, for example the way in which the furca is released by the retinaculum, how and where the mechanisms of spring and hydrostatic pressure originate, are still not properly understood. The morphology of the jumping apparatus of Orchesella cincta was investigated in detail using confocal laser scanning microscopy and MicroCT techniques for 3D reconstruction. Results The morphology of O. cincta with both flexed and extended furca is analysed and described. The abdominal musculature involved in the jumping mechanism and relevant structures of the exoskeleton of retinaculum and furca are described in detail. With the data obtained in this study, hypotheses can be made about (1) where and how the spring and hydrostatic pressure mechanisms originate; (2) which muscles act on the extension and flexion of the furca; (3) which muscles act on the retinaculum and (4) how the retinaculum is released from the furca. Conclusions The comparative morphological study proved informative, and shows how springtail jumping involves mechanisms unique to this taxon. Hydrostatic pressure regulation possibly varies between animals with distinct segmentation, and those with fused segmentation. Interesting cuticular characters were revealed, such as basal plates and sclerites related to the construction of the spring mechanism. The present study establishes itself as a model option for future morphofunctional studies on springtail’s jumping. Analysis of videos and images using a high speed camera will be useful for understanding how the jump develops through take-off, aerial and landing phases.

The status of Heteromurini Absolon & Ksenemann is analyzed and a new diagnosis is proposed to the tribe. New chaetotaxic characteres were added to distinguish Dicranocentrus Schött and Pseudodicranocentrus Mari Mutt. Alloscopus Börner, Heteromurtrella Mari Mutt and Verhoeffiella Absolon, originally proposed as subgenera of Heteromurus Wankel, are reviewed and a new diagnosis and generic status are proposed. The presence of the postantennal organ becomes the main characteristic to distinguish Alloscopus (present) and Heteromurtrella (absent). Alloscopus yosiius Mari Mutt, anteriorly synonymized with Alloscopus tenuicornis Börner, is revalidated. The absence of S0 macrochaeta on head of Heteromurus is reported now as a characteristic also shared with Heteromurtrella. Heteromurtrella zairensis Tshelnokov comb. nov. is transferred from Heteromurus by the presence of macrochaetae on abdomen I. Heteromurtrella anae sp. nov. from Brazilian Amazon is described and illustrated, including detailed dorsal chaetotaxy. This is the first record of Heteromurtrella in Brazil. Heteromurus now has 17, Alloscopus 10 and Heteromurtrella 20 valid species worldwide. An identification key and diagnosis for the six genera of Heteromurini and species of Alloscopus and Heteromurtrella are provided.

Orchesellinae specimens are distinguished from other Entomobryidae by a shorter fourth abdominal segment (length at the midline less than 1.8 times the third segment), generally more than four antennal segments, recurved labral setae and the presence of a complex metatrochanteral organ, with at least 11 spine-like setae, (Soto-Adames et al. 2008). Adult Dicranocentrus Schött specimens have the following characters: antennae with six segments, both fifth and sixth antennal segments annulated, 8+8 lenses in the eye patches, absence of a postantennal organ, apically rounded and/or truncated scales, pre-labral setae simple, not bifurcated, rows of spines on dens (present in most but not all species) and mucro bearing two teeth with a basal spine (Mari-Mutt 1976, 1981, Arlé & Mendonça 1982, Bellinger et al. 1996–2012). The genus is similar to other scaled Orchesellini genera such as Pseudodicranocentrus Mari-Mutt, 1981 and Dicranorchesella Mari-Mutt, 1977, but differs from these taxa by the presence of simple pre-labral setae (bifurcated in Pseudodicranocentrus) and by rounded and/or truncated scales (fusiform and apically pointed in Dicranorchesella) (Mari-Mutt 1977, 1980). Dicranocentrus is holotropical in distribution only four species recorded from Brazil: D. bicolor Handschin, 1924, D. silvestrii Absolon, 1903, D. termitophilus Handschin, 1924 and D. heloisae Arlé & Mendonça, 1982 (Abrantes et al. 2012). These species are restricted to northeastern and southeastern Regions (Abrantes et al. 2012). The new species is the first from Brazilian Amazon, north region of Brazil. The dorsal chaetotaxic scheme follows that of Mari-Mutt (1979).

Plumachaetas Salmon is a genus of Entomobryoidea with 11 valid species, all from Oceania. The genus is characterised by the presence of lanceolate scales, the subapical chaeta of the maxillary outer lobe thick and blunt, dental spines absent and a short mucro. In this paper we describe four new species of Plumachaetas from Oceania: P. belae sp. nov., P. loriensis sp. nov., P. mamuensis sp. nov. and P. wanangensis sp. nov. Plumachaetas belae sp. nov. and P. mamuensis sp. nov. are similar to each other, and to P. queenslandica (Schött) and P. yoshii Zhang & Deharveng, but are unique in the combination of dorsal and labial chaetotaxy. Plumachaetas loriensis sp. nov. resembles P. halmaherae (Yoshii & Suhardjono) and P. sunae Zhang & Deharveng but differs in labial, dorsal chaetotaxy and unguiculus shape. Plumachaetas wanangensis sp. nov. is similar to other taxa bearing a mucro with four teeth, but presents a unique combination of macrochaetae on thoracic and abdominal segments. All species are arboreal and were collected in Malaise traps set in humid rainforests. A map of the geographic distribution and ecological remarks on the genus are provided and a key to species with a table summarising the main morphological features of all described taxa in the genus.