The Lord Howe Island stick insect, Dryococelus australis, was once common on the island but was driven to extinction after the arrival of ship rats in the early 20 century [1, 2]. It was thought to be extinct for decades, until a tiny population of similar-looking stick insects was discovered 20 km away, on the islet of Ball's Pyramid, in 2001 [2]. Individuals from this population are currently being reared in Australia and elsewhere in the world, with the eventual goal of recolonizing Lord Howe Island [3]. Recent surveys of the wild population on Ball's Pyramid suggest that it is among the world's rarest species. However, there are significant morphological differences between Ball's Pyramid and museum specimens, and there has never been a genetic confirmation of the rediscovered population's species identity. Because Dryococelus is monotypic, there are also no known extant relatives for comparison. Using shotgun genomic data from the Ball's Pyramid population, we assembled a draft genome and the complete mitochondrial genome. We found that the genome is massive, over 4 Gb in size, and is most likely hexaploid. We re-sequenced mitochondrial genomes from historic museum specimens collected on Lord Howe Island before the extinction event. Sequence divergence between the two populations is less than 1% and is within the range of intraspecific differences between the museum specimens, suggesting that they are conspecific and that D. australis has successfully evaded extinction so far. This work highlights the importance of museum collections for taxonomic validation in the context of ongoing conservation efforts.
Stabilising microstructures and small organisms for microphotography can be frustrating. If it is desired to take photographs in water from structures just cleared in potassium hydroxide, some sort of stabilisation is necessary otherwise the structures drift. Similarly, specimens taken from glycerol or alcohol, or those placed in alcohol, drift even more as the alcohol evaporates. Bits of crushed coverslip, glass beads, micro pins and dobs of Vaseline® have all been used to help keep the structures in place. In an attempt to solve the problem of "drifting genitalia" a simple solution was inadvertently discovered. A method used for whole insects by Sam Droege and his colleagues of the United States Geological Survey (Droege 2016; USGS Bee Inventory and Monitoring Lab 2016) was adapted for use with insect genitalia.
Melbourne, B.A., Gullan, P.J. and Su, Y.N., I 997. Interpreting data from pitfall-trap sur veys: crickets and slugs in exotic and native grasslands of the Australian Capital Territory. A-lemoirs of the Musrn111 of Victoria 56(2): 361-367.We use data from a pitfall-trap survey of 23 grassland sites to examine the eff ect of grass land type on the abundance of crickets and slugs and to demonstrate the problems associated with interpreting data obtained by pitfall-trapping. The data presented here arc for four species of native cricket (Insecta: Orthoptera: Gryllidae: Bobi/la victoriae Otte and Alexan der, Te/eogryl/us commodus (Walker), Buangina ane111ba Otte and Alexander, Pteronemo bius arima Otte and Alexander) and five species of introduced slug (Gastropoda: Pulmonata: Limacidae: Deroceras reticu/atum (Mtiller), Lehmannia (Lehmannia) nycte/ia (Bourguignat). Limax maximus Linnaeus; Milacidae: Mi/ax gagates (Draparnaud); Arion idae: Arion intermedius Normand). The survey included three types of native grassland (Themeda, Stipa, Danthonia), two types of exotic grassland (Pha/aris, Avena), and two seasons (summer, autumn). In addition to the survey, the eff ect of habitat structure on the efficiency of pitfall traps was examined in a well-replicated field experiment. The exper iment was carried out in Themeda grassland, which was manipulated to create three levels of habitat structure. Habitat structure was found to aff ect pitfall-trap efficiency for crickets but not for slugs. We show that it is necessary to use knowledge of the effect of habitat structure on pitfall-trap efficiency for diff erent species to allow confident interpretation of data from field surveys. Grassland type had a significant eff ect on the abundance of both crickets and slugs. Bobi//a l'ictoriae and T. commodus were both found to have high abundances in Pha/ aris, an improved pasture. Slugs appear to be highly invasive of native grasslands.
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