Masaaki Murano

Effects of prey density on survival, feeding rate and development of zoeas of the red frog crab Ranina ranina (Crustacea, Decapoda, Raninidae)

Abstract The effects of prey density on growth and survival of larval Ranina ranina were examined. Five levels of prey density (0.05−5 Artemia nauplii ml −1 ) were tested for their effects on survival, intermolt period and growth at all the zoeal instars. Six or seven levels of prey densities (1−10 ml −1 ) were examined for feeding rate at instars I, III, V and VII. Survival decreased with decreasing prey density. Survival rate dropped to around 50% in 0.05 ml −1 to instar I, 0.1 ml −1 to instar II, 0.5 ml −1 at instar V, and 1 ml −1 after instar VI. Metamorphosis rate increased with increasing prey density, from 0% at 0.1 ml −1 to 100% at 5 ml −1 . Intermolt period and duration of the zoeal stages were longer at 0.05 and 0.1 ml −1 compared to 0.5−5 ml −1 . Growth of several body parts was lower at 0.05 and 0.1 ml −1 than at higher prey densities for instars III, V and VII. The external morphology of several appendages was less affected than was growth. A regression equation, F = M (1 − e − kp ) ( F =feeding rate, k =constant, M =calculated maximum feeding rate, p =prey density), was derived for the relationship between observed prey density and feeding rate. The optimal prey density necessary to ensure highest survival and the shortest intermolt period calculated using this regression equation was similar to results measured from the experiment in terms of survival, intermolt period and growth: it was 0.5 ml −1 at instar I, 0.6 ml −1 at instar III, 1.8 ml −1 at instar V, and 2.3 ml −1 at instar VII.

Larval feeding rhythms and food consumption by the red frog crab Ranina ranina (Decapoda, Raninidae) under laboratory conditions

Abstract Newly hatched R. ranina zoeas were held individually and fed a fixed number of Artemia nauplii at 25 and 29°C, to examine feeding rhythms and the quantities consumed. During the daytime zoeas ate on average 2.6 times more at 25°C and 2.8 times more at 29°C than at night, through all zoeal instars. Feeding activity during an instar was described by parabola-shaped quadratic or polynomial functions of days after ecdysis in later instars, although large individual variation was observed at both temperatures. Total quantities of prey consumed during each instar were expressed as exponential functions of an instar. Zoeas at 29°C ate 1.05–1.45 times as much prey during each instar and 1.47–1.90 times as much daily compared with those at 25°C. The total quantities of prey consumed during a day and during an instar were extremely high compared with other decapod species. Instar VII zoeas consumed 55% of the total prey intake during the zoeal period at 25°C and 51% at 29°C.

Systematic and ecological studies on mysidacea collected by the bottom-net

A list of the 21 species represented in the collection by the bottom-net is given. Of these, 5 are impossible to be identified with the already known species, especially 2 are reserved as their genera are undecided. It is found that there are 2 races inHolmesiella affinisIi, the large-sized and the small-sized, as like as the most related species,H. anomalaOrtmann. As to a species,Pteromysis amemiyaiIi, the development of the marsupium is discussed on the basis of an adult female collected by the ORI-net. The occurrence of 2 species,Petalophthalmus oculatusIllig andPseudomma callopluraHolt andTattersall, is a new record in the Pacific. For the former species, moreover, an ecological property of the habitat is discussed.

A Small Collection of Benthic Mysidacea From Coastal Waters in Suruga Bay, Japan

[Acht Mysideen Spezies wurden in der Bucht von Suruga gesammelt; vier von ihnen, namlich Pseudomma japonicum, Pleurerythrops secunda, Mysidopsis surugae und Mysidella nana, reprasentieren neue Arten und werden hier ausfuhrlich beschrieben und illustriert. Pseudomma sp. ist wahrscheinlich eine neue Art, aber der Autor hat mit der Errichtung davon gezogert weil die Proben zu sehr beschadigt waren. Hypererythrops zimmeri Ii, eine der drei ubrigen Spezies, wurde schon von Ii aus den Kustengewassern Japans beschrieben. In der vorliegenden Arbeit werden die Abweichungen von der Beschreibung durch den von Ii und einige nachtragliche Notizen vorgelegt., Acht Mysideen Spezies wurden in der Bucht von Suruga gesammelt; vier von ihnen, namlich Pseudomma japonicum, Pleurerythrops secunda, Mysidopsis surugae und Mysidella nana, reprasentieren neue Arten und werden hier ausfuhrlich beschrieben und illustriert. Pseudomma sp. ist wahrscheinlich eine neue Art, aber der Autor hat mit der Errichtung davon gezogert weil die Proben zu sehr beschadigt waren. Hypererythrops zimmeri Ii, eine der drei ubrigen Spezies, wurde schon von Ii aus den Kustengewassern Japans beschrieben. In der vorliegenden Arbeit werden die Abweichungen von der Beschreibung durch den von Ii und einige nachtragliche Notizen vorgelegt.]

A revision of East Asian Acanthomysis (Crustacea: Mysida: Mysidae) and redefinition of Orientomysis, with description of a new species

Twenty species of Acanthomysis s. l., distributed in Japanese, Korean and Chinese coastal waters, are revised. These species are distinguished from Acanthomysis s. str. by the following characters: the carpopropodus of the endopod of the third to eighth thoracic limbs divided into three to eight subsegments; the exopod of the fourth male pleopod with two long subequal terminal setae; the telson long linguiform or triangular without basal dilated portion and armed with spines throughout margins. On the basis of these characters, the genus Orientomysis, which was revived by Holmquist (1981b) and comprised O. japonica and O. mitsukurii, is redefined and recognized to contain the following 18 valid species: O. aokii, O. aspera, O. crassispinosa, O. fujinagai, O. hwanhaiensis, O. koreana, O. leptura, O. meridionalis, O. okayamaensis, O. pseudomitsukurii, O. robusta, O. rotundicauda, O. sagamiensis, O. serrata, O. sheni, O. tamurai, O. tenella, and O. tenuicauda. Acanthomysis longicauda and A. nakazatoi are synonymized with O. rotundicauda and O. japonica, respectively. A new species, O. arenaria, is described from Japan.

Seasonal Variations in Abundance and Size Composition of the Lobate Ctenophore Bolinopsis Mikado (Moser) in Tokyo Bay, Central Japan

Surveys of the abundance and size composition of the ctenophore Bolinopsis mikado were conducted in Tokyo Bay over a 5-year period from 1990 to 1994. B. mikado appeared throughout the year, and its mass occurrence was observed between August and November; annual maximum abundance ranged from 19 to 91 ind. m−2. Water temperature seems to influence the seasonal variation of B. mikado abundance. Environmental conditions (e.g. rough waters due to a typhoon) and predation by the beroid ctenophore Beroe cucumis appear to affect annual variations of B. mikado abundance. Size frequency distributions of B. mikado indicated that its reproduction was most active in summer and fall but occurred throughout the year in Tokyo Bay. A sharp decline of the copepod population in August 1990 was probably due to predation by B. mikado which was very abundant at that time; its predatory impact was estimated to be 24 % day−1.

Mysidacea from Coastal Waters of Iriomote Island, Ryukyu Islands, Southwestern Japan, with Descriptions of Three New Species

ABSTRACT Fifteen mysid species, including three new species, are reported from Iriomote Island, Ryukyu Islands, Japan. A new species, Iiella iriomotensis, is distinguished from related species by the shapes of the rostrum and the telson cleft, the number of spines arming the frontal margin of the labrum, and the endopod of the uropod being shorter than the exopod. Nipponomysis minuta, new species, closely resembles Nipponomysis imparis in respect to the fourth male pleopod, but is distinguished by the shorter telson and the smaller number of spines on the lateral margin of the telson and on the inner margin of the endopod of the uropod. Anisomysis hashizumei, new species, is distinguished from related species by a combination of characters found in the fourth male pleopod and the telson. Haplostylus pusillus, which has been known only from the Indian Ocean, is reported from the Pacific Ocean for the first time. Four species, Siriella inornata, S. anomala, Anchialina zimmeri, and Pseudanchialina pusilla are new records from Japanese waters.

A New Species of Archaeomysis From Coastal Waters of Japan (Mysidacea, Gastrosaccinae)

A large number of Japanese specimens previously identified as Archaeomysis grebnitzkii were examined and compared with specimens from the Bering Sea and Pacific coast of North America. This study demonstrates that the Japanese population of Archaeomysis grebnitzkii sensu Ii (1964) differs consistently from those of the latter locations, particularly in the shape of the telson and the male 3rd pleopod, so as to constitute a new species, described here as A. japonica n. sp. A short note is included at the end of this paper reporting some observations on the biology of the species noted during this study.

FOUR NEW MYSIDS FROM CALIFORNIAN COASTAL WATERS

One new genus and four new species of Mysidacea collected from Californian coastal waters are described. .dmathimvsis rrigibbu. new species. is unique in having three tubercles on the carapace and is further distinguished from other species of the genus by the antennal scale, mandibular palp. fifth male pleopod, and uropod. This is the first record of the genus occumng on the Pacific coast. ~4cunthomysis californicu. new species, is recognized as a new species by the smooth abdominal somites and the shape and armature of the telson. .-icunthomysis brunneu. new species, is distinguished by the shape of the rostral plate. the slender antennal scale, the slender side lobe of the fourth male pleopod, and the shape and armature of the telson. The new genus Hippucunrhomysis is distinguished from allied genera of the tribe Mysini by having an expanded and knife-shaped first segment of the exopod of the fourth male pleopod. The species described herein are based on specimens collected during ecological investigations in Californian coastal waters by the National Marine Fisheries Service of the United States. In this paper we describe 4 new species, one of which is placed in a new genus. The type specimens are deposited in the National Museum of Natural History (USNM), Smithsonian Institution, Washington. D.C. Amathimysis trigibba, new species

BATHYPELAGIC MYSIDS FROM THE NORTHEASTERN PACIFIC

ABSTRACT Deep-water samples off the Oregon coast yielded two new genera, four new species, and resulted in a further description of a previously described species of the Suborder Mysida. The following mysids are described: (1) The new genus Bacescomysis, which includes B. pacifica, new species, and five species of Hansenomysis: H. birsteini Băcescu, H. peruvianus Bacescu, H. tattersallae Băcescu, H. abyssalis Lagardere, and H. atlantica Lagardere. In this genus, closely related to Hansenomysis, the unjointed plate on the exopod of the uropod is the distinguishing feature. Bacescomysis pacifica is distinguished by its eyeplate, second thoracic endopod, second male pleopod, and telson. (2) The new species Boreomysis pearcyi is unique in its antennal scale, third thoracic endopod, telson, and body length. (3) Dactylerythrops latisquamosa, new species, is distinguished by its telson, eye, antennal scale, and endopod of first limb. (4) Paramblyops sp. is recognized as a new species by its rostrum and eyeplate, but is too damaged for a complete description. (5) The new genus Gibbamblyops resembles Dactylamblyops and Pseudamblyops, but is distinguished by the anterior margin of the carapace, eye, antennal peduncle, fourth male pleopod, and telson. These characters also define the uniqueness of its species, G. longisquamosa. (6) Thalassomysis tattersalli Nouvel, 1942, had been partially described from a single specimen. Four additional specimens of this species are recorded here. Slight differences are discussed, plus a complete description of the antennal peduncle and telson, which were lacking in the original description, are provided here. (7) Seven specimens of Holmesiella anomala Ortmann provided information on regional variation and allowed an opportunity for detailed drawings.