In this study we describe one new species of Dactylogyrus Diesing, 1850 and three new species of Bivaginogyrus Gussev and Gerasev in Gussev, 1985 (Monogenea: Dactylogyridae) from two freshwater fishes Gnathopogon elongatus elongatus (Temminck and Schlegel, 1846) and G. caerulescens (Sauvage, 1883) (Cypriniformes: Gobionidae) endemic to Japan. Further, G. elongatus is a new host record for Paradiplozoon skrjabini Achmerov, 1974 (Monogenea: Diplozoidae). Dactylogyrus tamoroko n. sp. is most similar to D. chenjiagengi Zhang in Zhang, Zhou, and Wen, 1990, D. clypeatus Gussev, 1955, and D. gnathopogonis Yamaguti, 1963; it differs from these three congeners by the bifurcate base of the accessory piece. Bivaginogyrus japonicus n. sp. is close to D. polylepidis Alvarez Pellitero, Simon Vicente, and Gonzalez Lanza, 1981, but it can be separated from the latter species based on its uniform-sized marginal hooks. The new species was connected to the cartilage tissue of the gill using filament-like structures, which are assumed to be derived from secretions of the reservoirs associated with each marginal hook. Bivaginogyrus cingulatus n. sp. resembles D. navicularis Gussev, 1955, D. trullaeformis Gussev, 1955, and D. imberbis Wu and Wang, 1983, but the new species is distinguished from these three species by having its inconspicuous outer roots. Bivaginogyrus exiguus n. sp. is comparable to D. pandus Wu and Wang, 1983 and D. colpodes Wu, Wang, and Song, 1983, but differs from these two species in having a shorter penis. Molecular phylogenetic analysis indicates that Bivaginogyrus is a paraphyletic group and shows affinity to “Dactylogyrus” species parasitic on gobionid fishes. However, most of those closely related Dactylogyrus species are yet to be described for their internal morphology and should accordingly be redescribed. The three new species of Bivaginogyrus are assumed to have been co-introduced along with G. e. elongatus into non-native regions of this host.
The 2023 Species Diversity Award-Winner Article
The taxonomic status of millipedes of the genus Spirobolus Brandt, 1833, referred to as “Yaeyama-maruyasude” from the Yaeyama Islands, Ryukyu Islands, Japan, was unresolved. We assess the taxonomic status of these Yaeyama Spirobolus sp. using an integrated morphological and molecular approach, and describe them as a new species, S. akamma sp. nov., for which partial sequences of the nuclear 28S ribosomal RNA, mitochondrial cytochrome c oxidase subunit I, and 16S ribosomal RNA markers are provided. This new species differs from continental China and Taiwan endemic congeners in anterior gonopod morphology (in having an elongate and subtriangular coxa, and a pentagonal mesal sternal process), posterior gonopod morphology (in having a coronoid prefemoral endite with rounded distal end, and an elongate telopodite), and in having four serrations on the cyphopod lateral flange.
The 2023 Species Diversity Award-Winner Article
We establish a new genus of candimboidid polyclad, Chimaeriplana gen. nov., based on a new species, C. japonica sp. nov., collected from Kanagawa, the coast of Sagami Bay, Japan. Chimaeriplana japonica sp. nov. is characterized by (i) an interpolated prostatic vesicle with a seminal vesicle, (ii) a penis stylet with a split tip, (iii) numerous prostatoid organs in the male atrium, (iv) a bursa copulatrix, and (v) without Lang’s vesicle. In addition, we modify the definition of Candimboididae.
The 2023 Species Diversity Award-Winner Article
Graveyards of Giant Pandas at the Bottom of the Sea? A Strange-Looking New Species of Colonial Ascidians in the Genus Clavelina (Tunicata: Ascidiacea)
Released on J-STAGE: February 01, 2024 | Volume 29 Issue 1 Pages 53-64
Naohiro Hasegawa, Hiroshi Kajihara
Redescription of Bicotyle reticulata (Monogenea: Heteraxinidae) from Pampus punctatissimus (Scombriformes: Stromateidae) in the Seto Inland Sea, Japan
Released on J-STAGE: April 24, 2024 | Volume 29 Issue 1 Pages 151-160
Yusuke Kamio, Kanna Yamamoto, Masato Nitta
Morphological and Molecular Characteristics of Two Species of the Genus Rhadinorhynchus (Palaeacanthocephala: Echinorhynchida) from the Western Pacific
Released on J-STAGE: May 24, 2024 | Volume 29 Issue 1 Pages 171-178
Yuki Kita, Masato Nitta, Hiroshi Kajihara
Testing the Species Status of the Chromodorid Nudibranch Goniobranchus aureopurpureus (Mollusca: Gastropoda)
Released on J-STAGE: April 24, 2024 | Volume 29 Issue 1 Pages 141-150
Haruki Ishiyama, Yuki Oya, Nerida G. Wilson, Hiroshi Kajihara
Phylogenetic Relationships and New Classification of the Superfamily Scorpaenoidea (Actinopterygii: Perciformes)
Released on J-STAGE: March 30, 2018 | Volume 9 Issue 1 Pages 1-36
Hisashi Imamura
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