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Neoclytus acuminatus acuminatus, the red-headed ash borer, is a wood-boring longhorn beetle (Cerambycidae: Cerambycinae) native to North America and introduced in Eurasia and South America. Its larvae develop in dying or recently dead hardwood trees, including ecologically and economically significant species of ash, hickory, and oak. We sequenced, assembled, and annotated the genome of a female N. acuminatus and compared it to the publicly available genomes of other cerambycid species. The 508 Mb N. acuminatus genome assembly spanned 20 contigs (19 nuclear + 1 mitochondrial), with an N50 of 52.59 Mb and largest contig of 61.20 Mb. A moderately high fraction of the genome (62.63%) comprised repetitive sequences, with nearly all (99.4%) expected single-copy orthologous genes (BUSCOs) present and fully assembled. We identified 2 contigs as fragments of the N. acuminatus sex chromosome. Genome annotation identified 12,899 genes, including 109 putative horizontally transferred loci. Synteny analysis identified well-conserved blocks of collinearity between the N. acuminatus genome and other Cerambycidae. The genome contains a similar number of genes encoding putative plant cell wall degrading enzymes as other Cerambycidae. The N. acuminatus genome provides new insights into genome evolution in the family Cerambycidae, known for its rich diversity of xylophagous species, and provides a new viewpoint from which to study the evolution and genomic basis of traits such as wood-feeding and olfaction in beetles and other insects. 

Abstract Insect antennae are crucial sensory organs that house numerous sensilla with receptors for perceiving a wide variety of cues dominating their world. Historically, inconsistent terminology and criteria have been used to classify antennal sensilla, which has greatly impeded the comparison of data even across closely related species. Longhorn beetles (Coleoptera: Cerambycidae) are no exception to this quandary, and despite their prominent antennae, few studies have investigated their antennal morphology and ultrastructure, and none have compared sensillar diversity and variation among cerambycids. Existing studies of longhorn beetle antennal sensilla include only 29 species in five of the eight cerambycid subfamilies and include misidentified sensilla types and conflicting terminology. As such, it is very difficult to conduct comparative morphological studies of antennal sensilla in longhorn beetles and challenging to understand inter- and intra-specific variation in the sensory systems of these beetles. To facilitate future comparative studies, we reviewed all accessible published papers that have used scanning and transmission electron microscopy (SEM and TEM) to investigate antennal sensilla in cerambycids, and present a first attempt at standardizing the classification of their documented sensilla types and subtypes. Specifically, we discuss seven major types of antennal sensilla (Böhm bristles, sensilla chaetica, chemosensory hairs, sensilla basiconica, dome shaped organs, sensilla coeloconica, and sensilla auricillica). We also imaged the antennae of relevant species of longhorn beetles using SEM and included images exemplifying as many of the sensilla types and subtypes as possible.