Elena S. Kornienko

Illustrated key for the identification of brachyuran zoeal stages (Crustacea: Decapoda) in the plankton of Peter the Great Bay (Sea of Japan)

A dichotomous key for brachyuran megalopae from Peter the Great Bay (Russian waters of the Sea of Japan) is provided. The key covers 18 taxa identified to species level and uses only the external characters of larvae that are easy to observe with a stereomicroscope without specimen dissection. The key is mainly based on the new original descriptions of larvae obtained both from plankton samples and from laboratory culture. Period of occurrence of larvae of each species in the plankton is also presented.

Burrowing shrimp of the infraorders Gebiidea and Axiidea (Crustacea: Decapoda)

This review is devoted to the different aspects of biology of burrowing shrimp of the infraorders Gebiidea and Axiidea (Crustacea: Decapoda). Information on their taxonomy, morphology and physiology, distribution, burrow architecture, and trophic mode is reviewed. The peculiarities of breeding and development, life history, and the role in the ecosystem of these infaunal species are analyzed. Special attention is given to the species that inhabit Peter the Great Bay of the Sea of Japan.

The larval development of Pagurus proximus (Decapoda: Anomura: Paguridae) reared in the laboratory

The larval development of the hermit crab Pagurus proximus is described and illustrated from the larvae reared in the laboratory. The development included four zoea and a single megalopa, thus following the typical pattern in the Paguridae. At 20–22°C megalopa of P. proximus was attained 17 to 23 days after hatching. Morphological characters of zoea and megalopa of P. proximus are compared with those described for the related species P. brachiomastus . The distinctive differences between larvae of these two species lend support to the separation of P. proximus from P. brachiomastus. The main larval features allow to assign P. proximus larvae to the Group A of Pagurus larvae (typical representative: P. bernhardus ).

The complete larval development of the lobster shrimp Boasaxius princeps Boas, 1880 (Decapoda: Axiidea: Axiidae) obtained in the laboratory

The complete larval development of Boasaxius princeps (Boas, 1880) (Decapoda: Axiidea: Axiidae) is described and illustrated for the first time from material reared in the laboratory. The development includes eight zoeal stages and a single megalopal stage. At 20–22°C the first megalopa was attained 38 days after hatching. It is the first description of the larvae of a lobster shrimp with long development obtained under laboratory conditions. An identification key to zoeal stages of B. princeps is presented. Numerous characters show that zoeae of B. princeps are similar to the larvae of Axiopsis serratifrons. Thus, according to the overall similarities of the larval characters, Boasaxius and Axiopsis are closer to each other than other axiid genera.

Symbiotic Crab Sestrostoma balssi (Shen, 1932) (Varunidae: Gaeticinae) from Vostok Bay, Sea of Japan: A New Species for the Fauna of Russia

A symbiotic crab Sestrostoma balssi (Shen, 1932) (Varunidae: Gaeticinae) that lives in burrows of the large ghost shrimp Upogebia major (De Haan, 1841) and U. issaeffi (Balss, 1913) (Upogebiidae) was found in Vostok Bay (Peter the Great Bay, Sea of Japan) for the first time. The occurrence of mature and juvenile specimens indicates the existence of a stable population of this species in the investigated region. This finding substantially extends the distribution area of S. balssi in the Sea of Japan.

The Caridean Shrimp Lysmata vittata (Stimpson, 1860) (Decapoda: Hippolytidae): A New Species for the Fauna of Russia

The caridean shrimp Lysmata vittata (Stimpson, 1860) (Crustacea: Decapoda: Hippolytidae), which is found in the Pos’et Bay of the Sea of Japan is reported as new to the fauna of Russia. Sexually mature specimens of different ages were found at a depth of 2–3 m among large boulders on a sandy bottom. The presence of a stable population of L. vittata in the investigated region substantially extends the distribution area of this species in the Sea of Japan.

The number of zoeal stages in larval development of Nihonotrypaea petalura (Stimpson, 1860) (Decapoda: Axiidea: Callianassidae) from Russian waters of the Sea of Japan

Zoeal stages of the mud shrimp Nihonotrypaea petalura (Stimpson, 1860) (Decapoda: Axiiidea: Callianassidae) inhabiting Peter the Great Bay (Sea of Japan) is described and illustrated from the larvae reared in the laboratory individually. The development included seven zoeal stages before molting to the megalopa. At 22-23°C the first megalopa was attained 26 days after hatching. A range of the number of zoeal stages in the family Callianassidae is analyzed. The possibility of variation of the number of zoeal stages of burrowing shrimps in different populations of the same species and/or under different laboratory conditions is discussed.

The larval development of the mud shrimp Upogebia yokoyai Makarov, 1938 (Decapoda: Gebiidea: Upogebiidae) reared under laboratory conditions

Larval development of the mud shrimp Upogebia yokoyai Makarov, 1938 (Decapoda: Gebiidea: Upogebiidae) is described and illustrated for the first time from material reared in the laboratory. The development includes four zoeal stages and a megalopa. At 20–22°C the megalopa was attained 16 days after hatching. The zoeae of U. yokoyai are distinguishable from those of the sympatric species Upogebia major and Upogebia issaeffi, inhabiting Russian waters of the Sea of Japan, by the presence of two pairs of spines (posterolateral and posterodorsal), each on the fourth and fifth pleonal somites. The megalopa of U. yokoyai differs in the length of the rostral spine, shape of telson and number of antennular aesthetascs.

The species composition and pattern of distribution of hermit crabs (Decapoda: Paguroidea) in Vostok Bay, Sea of Japan

The species composition, abundance, and vertical distribution of hermit crabs (Decapoda: Paguroidea) were investigated in Vostok Bay, Sea of Japan, from September 2014 to September 2015. A total of seven species from two families were found in the monitoring area of approximately 5000 m2 located on the bottom within a depth range of 0–11 m: Pagurus minutus, P. proximus, P. brachiomastus, P. pectinatus, P. ochotensis, P. middendorffii (Paguridae), and Areopaguristes hirsutimanus (Diogenidae). Their population density varied from 22 ± 13 to 26 ± 2 ind./m2; the biomass varied from 55.76 ± 26.10 to 93.38 ± 27.00 g/m2. The species composition remained invariable throughout the study period. The proportions of species abundance changed between seasons, as this parameter is largely determined by seasonal migrations of hermit crabs. Pagurus minutus predominated in number in winter and spring (up to 71%); P. proximus, in summer and autumn (up to 47%). In autumn and spring, P. ochotensis and P. pectinatus constituted a major part of biomass (18–25% and 19–20%, respectively). The proportion of a previously abundant species, P. middendorffii, was very small (no larger than 1.3%) during the study period. Another four species of hermit crabs occurred in other parts of Vostok Bay; thus, the fauna of the bay currently includes 11 species of this group.

Illustrated key for the identification of brachyuran megalopae (Crustacea: Decapoda) in the plankton of Peter the Great Bay (Sea of Japan)

Abstract A dichotomous key for brachyuran megalopae from Peter the Great Bay (Russian waters of the Sea of Japan) is provided. The key covers 18 taxa identified to species level and uses only the external characters of larvae that are easy to observe with a stereomicroscope without specimen dissection. The key is mainly based on the new original descriptions of larvae obtained both from plankton samples and from laboratory culture. Period of occurrence of larvae of each species in the plankton is also presented.