Hokkaido University · Earth and Planetary Sciences
Professor Hiroshi Kajihara's research lab specializes in the systematics, taxonomy, and evolutionary morphology of nemerteans (ribbon worms), with a particular focus on the diversity and phylogenetic relationships within the class Palaeonemertea and the order Monostilifera. The lab conducts detailed morphological analyses of type specimens and newly collected materials to resolve species boundaries, validate taxonomic nomenclature, and revise higher-level classifications. Their work integrates historical literature with modern anatomical studies, often leading to the description of new species and the re-evaluation of long-standing taxonomic concepts. The lab also maintains a strong focus on Japanese marine biodiversity, contributing comprehensive faunal catalogs and critical assessments of species identities in regional faunas.
Figures are computed from collected data and may differ slightly.
Between the years 1995 and 2007, 48 nominal genera and 128 nominal species of nemerteans were established worldwide. During this period, taxonomic changes such as synonymization, alteration of affiliation to higher taxa, and resurrection of formerly invalid names were made for 26 genera and 69 species. The nominal genera and species established between 1995 and 2007, as well as the taxonomic changes made at the genus and species level, are listed here with their original citations. The type depo
A literature-based taxonomic catalogue of the nemertean species (Phylum Nemertea) reported from Japanese waters is provided, listing 19 families, 45 genera, and 120 species as valid. Applications of the following species names to forms previously recorded from Japanese waters are regarded as uncertain: Amphiporus cervicalis, Amphiporus depressus, Amphiporus lactifloreus, Cephalothrix filiformis, Cephalothrix linearis, Cerebratulus fuscus, Lineus vegetus, Lineus bilineatus, Lineus gesserensis, Li
We compared the anatomy of the holotype of the palaeonemertean Cephalothrix simula ( Iwata, 1952 ) with that of the holotypes of Cephalothrix hongkongiensis Sundberg, Gibson and Olsson, 2003 and Cephalothrix fasciculus ( Iwata, 1952 ), as well as additional specimens from Fukue (type locality of C. simula) and Hiroshima, Japan. While there was no major morphological discordance between these specimens, we found discrepancies between the actual morphology and some statements in the original descr
Four species of palaeonemerteans, including Carinina plecta sp. nov., Callinera nishikawai sp. nov., Hubrechtella ijimai comb. nov., and Hubrechtella kimuraorum sp. nov., are described from the Pacific coast of Honshu Island, Japan. The genus Coeia Takakura, 1922 is considered to be a subjective junior synonym of Hubrechtella Bergendal, 1902. Carinina plecta sp. nov. can be distinguished from other congeners by possessing a rhynchocoel wall principally composed of interwoven circular and longitu
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The nemertean order Monostilifera consists of 594 species in 127 genera and is distributed worldwide. Within the Monostilifera, two suborders have been recognized, Cratenemertea and Eumonostilifera. Within the latter, two, unranked clade names, Oerstediina and Amphiporina, were recently proposed without formal taxonomic definition. In this article, I give morphological circumscriptions and clade definitions for Cratenemertea, Eumonostilifera, Oerstediina, Plectonemertidae, Oerstediidae, and Amph
We performed molecular phylogenetic analyses using nucleotide sequence data from five genes (16S rRNA, cytochrome <i>c</i> oxidase subunit I, 18S rRNA, 28S rRNA, histone H3) determined from 36 specimens representing 25 (10 named, 15 unnamed) species of lineid heteronemerteans collected in Sagami Bay, Japan, along with other sequences obtained from public databases. External features of the 25 species are briefly described and illustrated. <i>Lineus fuscoviridis</i> Takakura, 1898 is transferred
Kajihara, Hiroshi, Olympia, Minerva, Kobayashi, Norio, Katoh, Toru, Chen, Hai-Xia, Strand, Malin, Sundberg, Per (2011): Systematics and phylogeny of the hoplonemertean genus Diplomma (Nemertea) based on molecular and morphological evidence. Zoological Journal of the Linnean Society 161 (4): 695-722, DOI: 10.1111/j.1096-3642.2010.00650.x, URL: http://dx.doi.org/10.1111/j.1096-3642.2010.00650.x
A new species of heteronemertean with branched proboscis, Gorgonorhynchus albocinctus sp. nov., is described based on the external feature and DNA sequences from a specimen collected subtidally among coral rubbles at a depth of about 6 m in a reef area around Taketomi Island in the Yaeyama Islands, southwestern Japan. It can be classified in the genus because the mode of proboscis branching is dichotomous, rather than alternating laterally. From the two known congeners G. repens The new species
Abstract With about 480 known species, Pilidiophora (phylum Nemertea) has been regarded as consisting of Hubrechtiiformes (~20 spp.) and Heteronemertea (~460 spp.). Most (~87%) of the latter belong to Lineidae (&gt; 400 spp.), while the systematics of non-lineid heteronemerteans remains largely untouched. To explore the phylogeny of non-hubrechtiiformid, non-lineid pilidiophorans, we performed multilocus molecular phylogenetic analyses with five genes (18S, 28S, H3, 16S and COI) from 41 newl
Nemertellina minuta Friedrich, 1935, sensu Yamaoka, 1940, from Akkeshi Bay, Japan, is fully redescribed as a new species, Nemertellina yamaokai. The main characters distinguishing this taxon from N. minuta are the presence of two pairs of cephalic furrows and cephalic glands, and the absence of dorsoventral muscles from the intestinal region.
The taxonomic identity of the palaeonemertean Cephalothrix linearis (Rathke, 1799) has been obscure for nearly two centuries, because its original description applies to almost any congeners, including Cephalothrix filiformis (Johnston 1828) and Cephalothrix rufifrons (Johnston, 1837), which occur commonly in the North Sea and adjacent waters. In this paper, I redescribe C. linearis based on two topotypes from Bergen, one herein designated as the neotype for C. linearis, because Rathke’s origina
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