Genome of the Lord Howe Island Stick Insect Reveals a Highly Conserved Phasmid X Chromosome.

We present a chromosome-scale genome assembly for Dryococelus australis, a critically endangered Australian phasmid. The assembly, constructed with Pacific Biosciences continuous long reads and chromatin conformation capture (Omni-C) data, is 3.42 Gb in length with a scaffold N50 of 262.27 Mb and L50 of 5. Over 99% of the assembly is contained in 17 major scaffolds, which corresponds to the species' karyotype. The assembly contains 96.3% of insect Benchmarking Unique Single Copy Ortholog genes in single copy. A custom repeat library identified 63.29% of the genome covered by repetitive elements; most were not identifiable based on similarity to sequences in existing databases. A total of 33,793 putative protein-coding genes were annotated. Despite the high contiguity and single-copy Benchmarking Unique Single Copy Ortholog content of the assembly, over 1 Gb of the flow-cytometry-estimated genome size is not represented, likely due to the large and repetitive nature of the genome. We identified the X chromosome with a coverage-based analysis and searched for homologs of genes known to be X-linked across the genus Timema. We found 59% of these genes on the putative X chromosome, indicating strong conservation of X-chromosomal content across 120 million years of phasmid evolution.

Morphological and Molecular Analysis of Australian Earwigs (Dermaptera) Points to Unique Species and Regional Endemism in the Anisolabididae Family.

Dermaptera (earwigs) from the Anisolabididae family may be important for pest control but their taxonomy and status in Australia is poorly studied. Here we used taxonomic information to assess the diversity of southern Australian Anisolabididae and then applied cox1 barcodes as well as additional gene fragments (mitochondrial and nuclear) to corroborate classification and assess the monophyly of the putative genera. Anisolabididae morphospecies fell into two genera, Anisolabis Fieber and Gonolabis Burr, based on paramere morphology. Combinations of paramere and forceps morphology distinguished seven morphospecies, which were further supported by morphometric analyses. The morphospecies were corroborated by barcode data; all showed within-species genetic distance < 4% and between-species genetic distance > 10%. Molecular phylogenies did not support monophyly of putative genera nor clades based on paramere shape, instead pointing to regional clades distinguishable by forceps morphology. This apparent endemism needs to be further tested by sampling of earwig diversity outside of agricultural production regions but points to a unique regional insect fauna potentially important in pest control.