Twelve specimens of fossil fish from the lacustrine sediments of the Middle Pleistocene Miyajima Formation of Shiobara Group in Tochigi Prefecture are described in this study. Prior to their description, the extant species Tribolodon hakonensis is osteologically examined for a detailed morphological comparison. Our study identified seven individuals of Tribolodon sp. and five individuals of indeterminate cyprinids in the examined fossil specimens. Tribolodon dominates the known published records of fossil fish from this formation, and we attempted to estimate the pH of the Paleo- Shiobara Lake based on the data of Japanese lakes with modern Tribolodon population.
Postcranial fossils of Cervus sp. (Mammalia, Artiodactyla, Cervidae) newly collected from the lower Pleistocene (ca. 2.00–1.95 Ma) Kasumi Formation of the Kazusa Group, Akishima, Tokyo, Japan are described in this study. They consist of a right radius, right ulna, left metacarpal, and left tibia of a single individual. This individual is probably subadult because of the incompletely fused epiphyses. It is morphologically well comparable to those of living sika deer (Cervus (Sika) nippon) and is smaller in size than those of living Père David’s deer (Elaphurus davidianus).
Two specimens of Pterygotrigla cajorarori Richards and Yato, 2012 (Perciformes: Scorpaenoidei: Triglidae) were collected from the Pacific coast, off Shizuoka Prefecture, one from Suruga Bay, and the other from Enshu Nada, Japan. The specimen from Enshu Nada is small (152.8 mm in standard length), lacking hyper-ossification on the rostral projection, and having characteristic coloration of small yellow ocelli scattered on the dorsal surface of the body and a small black blotch on the membrane between the second to third and the third to fourth rays of the second dorsal-fin. Until recently, this species had been collected in Japan only from Kochi Prefecture but, in the recent two years, it has been collected from Shizuoka Prefecture. We consider that this species has extended its distribution northward as a result of the increase in marine temperature. The specimen from Suruga Bay represents the northernmost distribution of this species.
Three specimens of Neomyxus leuciscus (Mugilidae) were collected from the waters around Chichi-jima Island, the Ogasawara Islands. One specimen (38.35 mm SL) provided new knowledge concerning the species’ initial morphological features and changes that occur from juvenile to adult: snout becomes relatively longer and teeth increase in number and size with growth. It is considered that these changes reflect the food habits as the species adapts to being a herbivore. Additionally, one specimen (135.25 mm SL) examined in this study suggests that mature individuals may exist in the waters around Chichi-jima Island. These specimens are biogeographically important in indicating that this species is reproducing albeit to a small degree in the waters around Chichi-jima Island.
A single specimen of the moray eel identified as Gymnothorax polyuranodon (Bleeker, 1853) recently collected from the freshwater area of a river in Iriomote Island, Yaeyama Islands, is the first record of the species from Japan. The specimen was characterized as follows: total vertebrae 147 (predorsal 10, preanal 72); body with irregular black specks; vertical fins low; jaw teeth in two or three irregular rows; anus posterior to mid-body; preanal length 54.2 % of total length, head length 9.3 %, trunk 44 %; body depth 4.1 at gill opening, 4.9 at mid-anus; predorsal length 83.1 % of head length, upper-jaw length 25.8 %, lower-jaw length 22.7 %, snout length 10.7 %, eye diameter 4.9 %, interorbital width 9.1 %; dorsal-fin height 29.7 % of body depth at anus. A new standard Japanese name “Kokuhan-kawautsubo” is proposed for the species. This seemingly rare occurrence of the species is considered to be natural dispersal; while an established population is unlikely, it is necessary to monitor its occurrence from a conservation perspective, with reference to previous cases of fishes inhabiting similar environments.
Phygadeuontinae (Hymenoptera, Ichneumonidae) is one of the poorly studied subfamilies in Japan. In this study, I study 28 genera and 61 species of Japanese Phygadeuontinae taxonomically and zoogeographycally. Seven genera, Diaglyptidea Viereck, 1913, Micraris Townes, 1970, Surculus Townes, 1970, Bentyra Cameron, 1905, Isadelphus Förster, 1869, Megacara Townes, 1970, and Tropistes Gravenhorst, 1829, are newly recorded from Japan. Micraris and Surculus are also newly recorded from the Palearctic region. The following 17 new species are described: Acrolyta japonicasp. nov.; Micraris ryukyuensissp. nov.; Surculus japonicussp. nov.; Bentyra ryukyuanasp. nov.; Paraphylax eleganssp. nov.; Pa. politussp. nov.; Pa. transstriatussp. nov.; Pa. yakushimensissp. nov.; Pa. yambarensissp. nov.; Hemiteles japonicussp. nov.; H. kurosp. nov.; H. maculipterussp. nov.; H. yamatonissp. nov.; Isadelphus nigrussp. nov.; Lochetica japonicasp. nov.; Tropistes shimizuisp. nov.; Uchidella toichiisp. nov. The following nine species are newly recorded from Japan: Acr. flavicoxis Sheng & Sun, 2014; Acr. rufocincta (Gravenhorst, 1829); Diaglyptidea conformis (Gmelin, 1790); Bathythrix margaretae Sawoniewicz, 1980; Ba. thomsoni (Kerrich, 1942); Dichrogaster nitida Sheng & Sun, 2014; Megacara similis Sheng, 1999; Orthizema semanotae Sheng & Sun, 2014; Mesoleptus laevigatus (Gravenhorst, 1829). Bathythrix narangae Uchida, 1930 is newly synonymized under Ba. kuwanae Viereck, 1912 (syn. nov.). Ethelurgus politus Townes, 1983 is newly synonymized under E. episyrphicola Kusigemati, 1983 (syn. nov.). Ethelurgus sodalis fuscipes Townes, 1983 is newly synonymized under E. kumatai Kusigemati, 1983 (syn. nov.). Furthermore, the taxonomic status of E. kumatai changed as a subspecies of E. sodalis (Taschenberg, 1865) (comb. nov.). Some new distribution records and a key to species of the 11 genera are also provided.
Libelloides ramburi (M’Lachlan, 1875) is a large insect of the order Neuroptera that inhabits good grasslands of Japan, and is a rapidly decreasing species in various places. It has been previously recorded from 12 points in Kanagawa Prefecture, but only a few records are known in recent years. Therefore, it has been regarded as an endangered species on the Kanagawa Prefecture Red List. Since confirming this species in 2017, the authors have intensively investigated distribution of this species in the prefecture. As a result, we we found the species at 20 localities, mainly in the former Fujino Town area of Midori Ward, Sagamihara City in the northern part of the prefecture. Even in a similar grassland environment, the species could not be found and its distribution was limited. The environment in which this species is distributed is grassland where artificially mowing has been continued. Such distribution environment is diverse, but its habitat stability is fragile. Although the number of localities has increased, it has become clear that the distribution is localized and threatened with extinction.