A new endemic species of Chicoreus from Savai’l, Samoa

A new species of Muricidae, Chicoreus (Triplex) tangaroai is described from the Samoan Infraprovince. This new taxa is compared with C. (T.) thomasi (Crosse, 1872) and C. (T.) lorenzi Houart, 2009, related species in the Marquesan Molluscan Province.

Six new species of Tonsilla Wang & Yin, 1992 (Araneae: Agelenidae) from southern China, with the first description of the male of T. yanlingensis (Zhang, Yin & Kim, 2000)

Six new species of the spider genus Tonsilla Wang & Yin, 1992 are described from southern China: T. jinyunensis sp. nov. (♂♀) from Chongqing, T. jiugongensis sp. nov. (♂♀) from Hubei, T. subtruculenta sp. nov. (♂♀), T. rutunda sp. nov. (♂♀) and T. yueliangensis sp. nov. (♂) from Guizhou and T. subrostrum sp. nov. (♂♀) from Hunan. In addition, T. yanlingensis (Zhang, Yin & Kim, 2000) is redescribed and its male is described here for the first time. Tonsilla subyanlingensis Liu & Xu, 2020 is transferred to Draconarius Ovtchinnikov, 1999, hence the new combination Draconarius subyanlingensis (Liu & Xu, 2020) comb. nov. is established. The female of T. subyanlingensis Liu & Xu, 2020 should be treated as T. yanlingensis (Zhang, Yin & Kim, 2000). Detailed descriptions, photographs of copulatory organs and somatic features, a distribution map and comparisons with closely related species are presented.

Identification and Characterization of Wall-Associated Kinase (WAK) and WAK-like (WAKL) Gene Family in Juglans regia and Its Wild Related Species Juglans mandshurica

Wall-associated kinase (WAK) and WAK-like kinase (WAKL) are receptor-like kinases (RLKs), which play important roles in signal transduction between the cell wall and the cytoplasm in plants. WAK/WAKLs have been studied in many plants, but were rarely studied in the important economic walnut tree. In this study, 27 and 14 WAK/WAKL genes were identified in Juglans regia and its wild related species Juglans mandshurica, respectively. We found tandem duplication might play a critical role in the expansion of WAK/WAKL gene family in J. regia, and most of the WAK/WAKL homologous pairs underwent purified selection during evolution. All WAK/WAKL proteins have the extracellular WAK domain and the cytoplasmic protein kinase domain, and the latter was more conserved than the former. Cis-acting elements analysis showed that WAK/WAKL might be involved in plant growth and development, plant response to abiotic stress and hormones. Gene expression pattern analysis further indicated that most WAK/WAKL genes in J. regia might play a role in the development of leaves and be involved in plant response to biotic stress. Our study provides a new perspective for the evolutionary analysis of gene families in tree species and also provides potential candidate genes for studying WAK/WAKL gene function in walnuts.

Divergence and introgression among the virilis group of Drosophila

Speciation with gene flow is now widely regarded as common. However, the frequency of introgression between recently diverged species and the evolutionary consequences of gene flow are still poorly understood. The virilis group of Drosophila contains around a dozen species that are geographically widespread and show varying levels of pre-zygotic and post-zygotic isolation. Here, we utilize de novo genome assemblies and whole-genome sequencing data to resolve phylogenetic relationships and describe patterns of introgression and divergence across the group. We suggest that the virilis group consists of three, rather than the traditional two, subgroups. We found evidence of pervasive phylogenetic discordance caused by ancient introgression events between distant lineages within the group, and much more recent gene flow between closely-related species. When assessing patterns of genome-wide divergence in species pairs across the group, we found no consistent genomic evidence of a disproportionate role for the X chromosome. Some genes undergoing rapid sequence divergence across the group were involved in chemical communication and may be related to the evolution of sexual isolation. We suggest that gene flow between closely-related species has potentially had an impact on lineage-specific adaptation and the evolution of reproductive barriers. Our results show how ancient and recent introgression confuse phylogenetic reconstruction, and suggest that shared variation can facilitate adaptation and speciation.

Two new species of Cunaxa (Acari: Prostigmata: Cunaxidae) from Vietnam

Two new mite species of the genus Cunaxa are described based on female specimens in Vietnam: Cunaxa oblongostriata sp. n. and C. sergeyenkoi sp. n. (Acari: Prostigmata: Cunaxidae). Cunaxa oblongostriata sp. n. differs from the related species, C. setirostris (Hermann, 1804), in having the propodosomal shield triangular and longitudinal striae between dorsal setae d1–d1; while in C. setirostris, the propodosomal shield is trapezoidal and striae between setae d1–d1 are transversal. Cunaxa sergeyenkoi sp. n. differs from two related species, C. bochkovi Khaustov & Kuznetsov, 1998 and C. womersleyi Baker and Hoffmann, 1948, by the basifemoral chetotaxy of legs I–IV: 4-4-2-1 sts; while C. bochkovi and C. womersleyi have the basifemoral chaetotaxy I–IV: 3-3-3-1 sts and 4-4-3-1 sts, respectively.

Chloroplast Genome Evolution in Four Montane Zingiberaceae Taxa in China

Chloroplasts are critical to plant survival and adaptive evolution. The comparison of chloroplast genomes could provide insight into the adaptive evolution of closely related species. To identify potential adaptive evolution in the chloroplast genomes of four montane Zingiberaceae taxa (Cautleya, Roscoea, Rhynchanthus, and Pommereschea) that inhabit distinct habitats in the mountains of Yunnan, China, the nucleotide sequences of 13 complete chloroplast genomes, including five newly sequenced species, were characterized and compared. The five newly sequenced chloroplast genomes (162,878–163,831 bp) possessed typical quadripartite structures, which included a large single copy (LSC) region, a small single copy (SSC) region, and a pair of inverted repeat regions (IRa and IRb), and even though the structure was highly conserved among the 13 taxa, one of the rps19 genes was absent in Cautleya, possibly due to expansion of the LSC region. Positive selection of rpoA and ycf2 suggests that these montane species have experienced adaptive evolution to habitats with different sunlight intensities and that adaptation related to the chloroplast genome has played an important role in the evolution of Zingiberaceae taxa.

Group II intron and repeat-rich red algal mitochondrial genomes demonstrate the dynamic recent history of autocatalytic RNAs

Background Group II introns are mobile genetic elements that can insert at specific target sequences, however, their origins are often challenging to reconstruct because of rapid sequence decay following invasion and spread into different sites. To advance understanding of group II intron spread, we studied the intron-rich mitochondrial genome (mitogenome) in the unicellular red alga, Porphyridium. Results Analysis of mitogenomes in three closely related species in this genus revealed they were 3–6-fold larger in size (56–132 kbp) than in other red algae, that have genomes of size 21–43 kbp. This discrepancy is explained by two factors, group II intron invasion and expansion of repeated sequences in large intergenic regions. Phylogenetic analysis demonstrates that many mitogenome group II intron families are specific to Porphyridium, whereas others are closely related to sequences in fungi and in the red alga-derived plastids of stramenopiles. Network analysis of intron-encoded proteins (IEPs) shows a clear link between plastid and mitochondrial IEPs in distantly related species, with both groups associated with prokaryotic sequences. Conclusion Our analysis of group II introns in Porphyridium mitogenomes demonstrates the dynamic nature of group II intron evolution, strongly supports the lateral movement of group II introns among diverse eukaryotes, and reveals their ability to proliferate, once integrated in mitochondrial DNA.

New species in Rejectaria Guenée (Lepidoptera: Erebidae: Herminiinae) with a focus on the Cyclanthaceae-feeders

Five species of Rejectaria Guenée, including two newly described, were reared from Asplundia utilis (Oerst.) Harling, Asplundia microphylla (Oerst.) Harling, Carludovica costaricensis (Harling) L.O. Williams, and Cyclanthus bipartitus Poit. ex A. Rich., all Cyclanthaceae, in Area Conservacion de Guanacaste (ACG), Costa Rica: R. villavicencia Dognin, 1924, R. villosa Druce, 1891, R. magas Druce, 1891, R. richardashleyi sp. n. and R. ritaashleyae sp. n.. These represent the only Noctuoidea known to feed on Cyclanthaceae. Related species with unknown foodplant associations include R. atrax Dognin, 1891, R. splendida Schaus, 1912, and R. paratrax sp. n., the last of which is described from French Guiana, Venezuela, and Panama. The nomenclatural and phylogenetic challenges within the Herminiinae and the origins of cyclanth-feeding relative to fern- and palm-feeding are discussed.

Unique structure and positive selection promote the rapid divergence of Drosophila Y chromosomes

Y chromosomes across diverse species convergently evolve a gene-poor, heterochromatic organization enriched for duplicated genes, LTR retrotransposons, and satellite DNA. Sexual antagonism and a loss of recombination play major roles in the degeneration of young Y chromosomes. However, the processes shaping the evolution of mature, already degenerated Y chromosomes are less well-understood. Because Y chromosomes evolve rapidly, comparisons between closely related species are particularly useful. We generated de novo long read assemblies complemented with cytological validation to reveal Y chromosome organization in three closely related species of the Drosophila simulans complex, which diverged only 250,000 years ago and share >98% sequence identity. We find these Y chromosomes are divergent in their organization and repetitive DNA composition and discover new Y-linked gene families whose evolution is driven by both positive selection and gene conversion. These Y chromosomes are also enriched for large deletions, suggesting that the repair of double-strand breaks on Y chromosomes may be biased toward microhomology-mediated end joining over canonical non-homologous end-joining. We propose that this repair mechanism contributes to the convergent evolution of Y chromosome organization across organisms.

Tick-Born Relapsing Fever and Genespecies Diversity of Borrelia: Current Status

Relevance. Tick-borne relapsing fevers caused by Borrelia species pathogenic for humans are not well understood. Aim of this review is to assess the genetic diversity of Borrelia with special attention to the relapsing fever group and phylogenetically related species carried by ticks. The review also provides up-to-date information on the main vectors and their geographic distribution, reservoirs of borrelia – pathogens, and potential pathogens of tick-borne recurrent fevers. Conclusions. New types of Borrelia, including a candidate, of relapsing fever clade and related phylogenetic lines/groups, which are carried not only by argasid, but also by solid-body ixodids ticks, deserve further study. The preservation of the epidemic potential of tick-borne relapsing fever can be facilitated by climatic changes, and poorly studied adaptation mechanisms of Borrelia to the range of vectors.