Gyo Itani

• PhD
• Professor at Kōchi University

The morphology of female bopyrids is adapted to parasitism, but understanding the function of their thoracic and mouth appendages is hindered by their small size and cryptic lifestyle, limiting detailed examination. This study aimed to clarify the function of the first oostegites and maxillipeds in bopyrid isopods infesting the branchial chamber of...

We revised the previous records of Clorida japonica Manning, 1978 and conducted extensive field and museum material surveys in Japan. The material examined included five species of the genus Clorida Eydoux & Souleyet, 1842 as follows: C. japonica; C. albolitura Ahyong & Naiyanetr, 2000; C. denticauda (Chhapgar & Sane, 1967); C. rotundicauda (Miers,...

The reproduction of bopyrid isopod parasites is thought to occur immediately following host ecdysis, but direct observations supporting this hypothesis are limited. The aim of this study was to describe the reproductive behaviour of the bopyrid isopod Bopyrus crangorum relative to host ecdysis based on video recordings. Several hours after host ecd...

The monotypic polynoid genus Arctonoella Buzhinskaja, 1967 comprises solely the type species A. sinagawaensis (Izuka, 1912), which was originally described from Tokyo Bay (central Japan), and subsequently recorded from China and the Russian Far East. The six specimens we collected together with the burrowing filter-feeding spoon worm Urechis unicin...

The ghost shrimp genus Callianassa Leach, 1814 is currently represented by six taxa, of which five are known from the eastern Atlantic and only C. persica Sakai, 2005 from the Persian Gulf. In this study, a new species of Callianassa is described and illustrated on the basis of material from the subtidal soft sediments (at 26–28 m depth) in Wakasa...

The species composition and prevalence of symbionts attached to the body surface of the burrowing shrimp Upogebia major(De Haan, 1841) were examined at three sites (Kobe, Arao, and Kuma-gawa) in the Ariake and Yatsushiro Seas of Kyushu, Japan, in spring and summer in 2017. At each sampling time per site, 15–46 U. major individuals were collected in...

Ikeda taenioides (Ikeda, 1904) (Annelida: Thalassematidae: Bonelliinae) is the world’s longest spoon worm species, which possesses an extremely long tape-like proboscis with a striped color pattern and a large brownish red trunk. This species is endemic to the Japanese Islands and inhabits a deep vertical burrow in intertidal and subtidal sand flat...

We investigated collections of the alpheid shrimp Stenalpheops Miya, 1997, symbiotic in the burrows of gebiidean and axiidean shrimps, in Tokyo Bay, Japan to clarify ontogenetic changes in the diagnostic morphology of the cheliped and uropod. The uropod flaps were found only among the largest male shrimp, none among females. The number of articles...

Although well over 300 species are known from the caridean shrimp genus, Alpheus, only less than 20 species have had their burrow morphology studied thus far. Therefore, we investigated the burrow morphology of Alpheus sp., which was formerly identified as A. euphrosyne richardsoni (sensu Miya 1995), at muddy tidal flats in Shikoku Island and Kii P...

Bopyrid isopods and rhizocephalan barnacles are obligate parasite crustaceans which harm their decapod hosts. However, to the best of our knowledge, studies have not compared which of these parasites has a greater parasitic effect on its hosts. Here, the parasitic effect of the bopyrid isopod, Allokepon hendersoni, and an unidentified sacculinid rh...

Ecological studies of the facultatively symbiotic goby Acentrogobius sp. 2 (sensu Akihito et al., 2013) are important because there is limited knowledge on the facultative relationship in goby-shrimp symbiosis in the Pacific. The present study surveyed the surface activity of Acentrogobius sp. 2 around the burrows of snapping shrimp (Alpheus brevic...

Many alpheid shrimps live symbiotically on the body surface or inside the bodies of other invertebrates, while others use burrows made by other animals. The burrow symbiosis of alpheid shrimps is poorly studied in the context of ecology, probably because the cryptic infaunal nature of the relationship is hard to observe. The limited knowledge of th...

Moulting is essential for crustacean growth, but is one of the causes of mortality, because a crustacean cannot move during and just after its ecdysis. In the cases of ectosymbiotic crabs, escape from the host's hostile response may also be a problem during its own ecdysis. In this study, Sestrostoma sp. (Varunidae), an ectosymbiotic crab which cli...

Many species of gobies live in close association with various burrowing crustaceans. Mugilogobius abei is a common species distributed in a variety of estuarine environments from tidal pools in mudflats to tidal channels, even in polluted areas. This goby is usually found resting under pebbles, but gobies have been reported to use the burrows of up...

Although inquilinism in the goby–alpheid shrimp association is well known, behavior inside the burrow remains unclear because it is difficult to observe. In this tank study, alpheid shrimp burrow morphology was investigated because it may reflect the behavior of the burrow inhabitants. The objective was to elucidate the effects of Acentrogobius sp....

Two species of bopyrid isopods infesting brachyuran crabs were first recorded from Japan. Allokepon hendersoni (Giard and Bonnier, 1888) of the subfamily Keponinae, infesting Charybdis bimaculata, was collected in Tosa Bay, Pacific coast of southern Japan. This species is a branchial parasite of portunid crabs, so far collected in India infesting C...

Pseudopinnixa carinata (Crustacea: Decapoda: Varunidae) is a monotypic rare brachyuran endemic to the Japanese coast. Seventeen specimens of the crab were collected from tidal flats in Yamaguchi and Kochi Prefectures, Japan. The collection from Kochi Prefecture sets a new record from the Pacific coast of Shikoku. A review of P. carinata collection...

The effects of infestation by the bopyrid isopod Megacepon goetici on the varunid crab Gaetice depressus were investigated. This crab is one of the most common crabs in Japanese intertidal shores where it plays a key role in structuring the benthic community. Samples were collected in Wakayama Prefecture, Japan. From a total of 1694 crabs, 61 (3.6%...

A new genus of the family Callianassidae, Laticallichirus, is established for "Neocallichirus" grandis Karasawa & Goda, 1996, a ghost shrimp species heretofore represented only by fossil materials from the middle to upper Pleistocene of Japan. The newly collected specimens came from two Japanese localities: Numazu, Shizuoka Prefecture (Suruga Bay)...

Eight specimens of a threatened goby, Gymnogobius macrognathos (30.04– 38.87 mm in standard length), were collected on a mudflat characterized by abundant burrows of Upogebia major, at Akkeshi, Hokkaido, northern Japan in August 2017. Because G. macrognathos specimens were collected directly from U. major burrows by suction pump, and were also coll...

Ikedosoma elegans (Ikeda, 1904) (Annelida: Echiura: Thalassematidae) is a rare, large deep-burrowing spoon worm that has been observed only in Japan. This species was first described based on the specimens collected from Misaki, Sagami Bay (Kanagawa Prefecture), eastern Japan, in 1902. Since the first description, this species has not been collecte...

The Alpheus brevicristatus De Haan, 1844 is one of the commonest shrimp species inhabiting the tidal flats in Japan. This species is sometimes accompanied by the facultative symbiotic goby, Acentrogobius spp. Here, we investigated the burrow morphology of A. brevicristatus in a tidal flat of Uranouchi Inlet, Kochi Prefecture, Japan. We also reviewe...

The life cycle and precopulatory mate guarding behavior of the poecilostomatoid copepod Goidelia japonica associated with the spoon worm Urechis unicinctus (Echiura) are described based on specimens from 19 worms collected from western Japan. A total of 676 copepods were collected from the host’s rectum (494 copepods) and body surface (182 copepods...

We investigated the spawning nests of Gymnogobius macrognathos on a tidal flat in the Tatara River, Fukuoka Prefecture, Japan. Digging uncovered 19 spawning nests. The number of eggs and the standard length of the guarding male were positively correlated. Nine spawning nests were examined using in situ resin casting. All casts had structures charac...

Sestrostoma toriumii (Takeda, 1974) (Varunidae) is a symbiotic brachyuran crab that uses the burrows of the mud shrimp Upogebia yokoyaiMakarov, 1938 (Upogebiidae) in tidal flats along the coasts of Japan, Korea, and Hong Kong. We studied the host specificity of S. toriumii by quantifying the use of alternative hosts, namely, the callianassid shrimp...

The rhizocephalan Sacculina shiinoi sp. nov. parasitizes three species of Upogebia in Japan. It is described morphologically and compared with another Upogebia parasite, Sacculina upogebiae Shiino, 1943 from Japan and Korea. These two species are the only sacculinids that parasitize mud shrimps. DNA analyses clearly show the two species to be separ...

In-situ physiological parameters of Mytilus galloprovincialis and Perna viridis were examined by conducting an underwater chamber experiments at three study sites in the western Japanese coastal waters along the Pacific Ocean side in summer and winter. Estimated growth energy balance derived by scope for growth (SFG) demonstrated a deficit of growt...

The aim of this study was to clarify the relationship between consciousness of science and the type of interests in science and technology of children and their parents who participated in the Youngsters’ Science Festival 2011-2013 in Kochi held in November or December of 2011 to 2013. One question asked which presentations among the 38 presentatio...

We investigated the estuarine goby's (Eutaeniichthys gilli) utilization of mud shrimp (Upogebia yokoyai) burrows in laboratory experiments at Kochi, Japan. The goby utilized the shrimp burrow in the presence of the host, without predators, when the mud surface was covered with water. The goby spent one quarter to half the time in shrimp burrows in...

The present status and problems of threatened benthic animals in the tidal flats of Japan are discussed. These issues came to light during the editing process of “Threatened Animals of Japanese Tidal Flats: Red Data Book (RDB) of Seashore Benthos ” (Japanese Association of Benthology, 2012). In this book, 651 species (462 molluscs, 138 arthropods,...

Use by a symbiotic crab Sestrostoma toriumii of burrows of a mud shrimp Upogebia yokoyai was investigated in laboratory experiments. Crabs used shrimp burrows in the presence of the host when the mud surface was covered with water. Crabs entered shrimp burrows soon after introduction to the tank (taking a mean of 656 s to enter), where they spent 6...

The gobies Eutaeniichthys gilli and Gymnogobius scrobiculatus were collected from burrows of the mud shrimp Upogebia yokoyai at low tide by digging and using a yabby pump from April 2007 to September 2008 at Susaki Bay, Kochi Prefecture, Japan. A total of 144 E. gilli and 103 G. scrobiculatus were collected. Densities of E. gilli and G. scrobiculat...

The green mussel Perna viridis, a sessile bivalve of tropical origin, was first introduced into Japanese waters in 1967. This mussel was present in Uranouchi Inlet on the south coast of Shikoku by the 2000s and was found to be widely distributed there in 2008. The survival rates of overwintering P. viridis and the corresponding water temperature re...

The introduced Asian parasitic bopyrid isopod, Orthione griffenis, was first discovered on the Pacific coast of North America in Washington in 1988 and next in California in 1992. The range of Orthione presently extends from British Columbia to Baja California, where it infests at least two species of the native estuary mud shrimp, Upogebia. Intens...

Zoanthids (Cnidaria, Hexacorallia) of the genus Epizoanthus are often found in association with other marine invertebrates, including gastropods and hermit crabs. However, little information exists on the specificity and nature of these associations due to a lack of investigation into Epizoanthus species diversity, and the taxonomy of Epizoanthus i...

The burrow morphology of the mud shrimp Upogebia yokoyai was investigated on a tidal flat in the Nanakita River mouth in north-eastern Japan using in situ resin casting. A total of 26 burrow casts were recovered, including those of 16 large shrimps and 10 small shrimps. Burrows of large shrimp were relatively simple and Y-shaped with depth exceedin...

Males and females of the commensal protandric bivalve Pseudopythina subsinuata have paired seminal receptacles, the interior of which contains many slender elongate cells. The testis produces small euspermatozoa and comparatively few and much larger paraspermatozoa. The ⩽16-μm-long and 3–5-μm-thick paraspermatozoa have a terminally placed irregular...

The green mussel, Perna viridis, is native to the tropical Indo-Pacific region but has recently been introduced worldwide. Although the native mussel populations of P.viridis in India suffer from parasitic effects of the pinnotherid crab Arcotheres placunae, there have been no previous reports of pinnotherid crabs in P.viridis in Japan. We investig...

Macrosymbiosis, a macroscopic-scale interspecific association, between the myid bivalve Cryptomya and thalassinidean shrimps is described. In modern tidal flats, living individuals of Cryptomya truncata are observed to protrude their posterior ends into the burrow lumen of thalassinidean shrimps such as Nihonotrypaea japonica and Upogebia yokoyai....

The morphology of burrows constructed by the upogebiid mud shrimps Austinogebia narutensis and Upogebia issaeffi was studied using resin castings of burrows in situ on Mukaishima Island, Seto Inland Sea, Japan, where the two species occurred sympatrically. The burrow structure of both shrimps is a relatively simple Y-shaped pattern, which is typica...

Relative growth of cheliped and abdomen was studied in the thalassinidean shrimp Laomedia astacina de Haan, 1841 based on samples taken from the Seto Inland Sea, Japan. A total of 108 individuals was collected and analysed. The sex ratio did not differ from 1:1 and sexual size dimorphism was not evident. Laomedia astacina was heterochelous, with th...

The morphology of burrows constructed by the eel goby Taenioidescirratus was studied using resin castings of burrows insitu as well as aquarium observations. Burrows had several openings, one of which was associated with a crateriform mound. The structure of the burrows consisted of the mound, gently sloping interconnected tunnels, and many short c...

The symbiotic association of the myid bivalve Cryptomya (Venatomya) truncata with thalassinidean shrimps was investigated together with morphometric variation on tidal flats in western Japan, including the Nansei Islands. Several specimens of C. truncata were found buried very close to the burrows of Upogebia major, U. yokoyai, U. carinicauda and C...

The behaviour of two ectosymbiotic animals, Peregrinamor ohshimai (a bivalve attached to the ventral cephalothorax of the host), and Phyllodurus sp. (a bopyrid isopod attached to the second pleopod of the host), during ecdyses of the host thalassinidean Upogebia shrimps was studied by time-lapse video of infested shrimps. In the intermoult stages o...

A unique scale worm Hesperonoe hwanghaienssi Uschakov and Wu, 1959 (Polychaeta: Polynoidae) was collected from tidal flats in Japan and is described here taxonomically as the second record of this species since its original description from Chinese specimens. Some morphological features of our specimens differed slightly from the original descripti...

A new species of the hitherto monotypic bivalve genus Peregrinamor (Galeommatidae) was found attached to the ventral side of the cephalothorax of a small thalassinidean shrimp, Upogebia carinicauda (Stimpson, 1860) (Upogebiidae) collected from tidal flats of Amami-Ohshima Island, Ryukyu Archipelago in Japan. The bivalve is dorso-ventrally flattened...

Hitherto, more than 300 species of isopod crustaceans have been reported in Japan and its neighboring waters, but no comprehensive catalogue has been published in this country. Therefore, in order to promote studies on the group, Saito has prepared a tentative catalogue on isopod crustaceans in Japan. Nunomura (on all the order but the suborder Epi...

Ecological, behavioural and anatomical observations of a commensal bivalve, Peregrinamor ohshimai (Mollusca: Galeommatoidea), were carried out in a tidal mudflat in the Seto Inland Sea, Japan. The bivalve attached specifically to the longitudinal groove of the ventral side of the cephalothorax of thalassinidean burrowing shrimps, Upogebia major and...