記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Zookeys  

The genus Monomorium is an important phylogenetic group, notable for its taxonomic complexity and the presence of several well-known tramp species. In this study, we present a description of M. brachypterum sp. nov. from southern Japan along with an updated key to the Japanese species of the genus based on the worker caste. Molecular phylogenetic analysis using 13 protein-coding genes of the mitochondrial genome indicated that this new species is most closely related to M. intrudens. Within their overlapping distributions, analyses based on partial sequences of the mitochondrial COI gene showed that the two species are phylogenetically distinct. The queens of M. brachypterum are distinguished from those of M. intrudens by degenerated wings, suggesting contrasting dispersal strategies between the two sister species. In addition, a phylogenetic analysis performed for the Japanese Monomorium species provides support for the repeated evolution of diverse reproductive systems within this genus. The present study highlights a wide variety of evolutionary trends in the nest-level reproductive system, even among closely related species.

DOI： 10.3897/zookeys.1250.150776

Open Access

Web of Science

Scopus

PubMed

掲載種別：研究論文（学術雑誌）   出版者・発行元：Magnolia Press  

The ant genus Monomorium is one of the most species-rich but taxonomically problematic groups in the hyperdiverse subfamily Myrmicinae. An East Asian species, M. triviale Wheeler, produces both reproductive queens and sterile workers via obligate thelytokous parthenogenesis. Here, we describe the immature forms of M. triviale based on light and scanning electron microscopy observations, with a note on the striking caste dimorphism in the last larval instar. The last-instar queen larvae were easily recognized by their large size, “aphaenogastroid” body shape, and rows of doorknob-like tubercles on the lateral and dorsal body surface. This type of queen-specific structure has not been found in ants in general, let alone congeneric species found in Japan. In stark contrast to the queen larvae, worker larvae showed a “pheidoloid” body shape and a body surface similar to other ants. The worker larvae were estimated to have three instars, consistent with previously described congeners. The pupae of both castes had no cocoon, a characteristic commonly described in other Myrmicinae species. In total, the developmental period from egg to adult worker averaged 59 days under 25°C. We discuss possible functions of the tubercles of queen larvae based on previous studies.

DOI： 10.11646/zootaxa.5105.2.5

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/23802359.2021.1970632

Open Access

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

We report comprehensive evidence for obligatory thelytokous parthenogenesis in an ant Monomorium triviale. This species is characterized by distinct queen-worker dimorphism with strict reproductive division of labor: queens produce both workers and new queens without mating, whereas workers are completely sterile. We collected 333 nests of this species from 14 localities and three laboratory-reared populations in Japan. All wild queens dissected had no sperm in their spermathecae. Laboratory observation confirmed that virgin queens produced workers without mating. Furthermore, microsatellite genotyping showed identical heterozygous genotypes between mothers and their respective daughters, suggesting an extremely low probability of sexual reproduction. Microbial analysis detected no bacterial genera that are known to induce thelytokous parthenogenesis in Hymenoptera. Finally, the lack of variation in partial sequences of mitochondrial DNA among individuals sampled from across Japan suggests recent rapid spread or selective sweep. M. triviale would be a promising model system of superorganism-like adaptation through comparative analysis with well-studied sexual congeners, including the pharaoh ant M. pharaonis.

DOI： 10.1371/journal.pone.0246710

Open Access

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-020-77683-x

Open Access

Web of Science