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Pandalus species display the following features that make it difficult to apply traditional age-based stock assessment models: (i) difficulty of determining age in the absence of hard parts retained through the molt; (ii) sex change in which individuals mature first as males and then transform to females; and (iii) potentially strong influence of environmental conditions on recruitment population dynamics. In this context, we propose a seasonal, size-structured assessment model dedicated to stock assessment of hermaphroditic Pandalidae. The modeling framework incorporates a submodel for changes of length at sex transformation and functions to incorporate environmental effects on recruitment dynamics. The model can be directly fitted to length-structured data, overcoming the length to age conversion problem. The model has a seasonal time step that allows it to account for seasonal variations in biological processes and fishing patterns. The model provides stock assessment outputs, such as fishing mortality and stock biomass estimates, and sex-specific abundance-at-length. The model is applied to the exploited shrimp stock of Pandalus borealis in the Gulf of Maine as an example of its utility. The model proposed in this study is flexible and generic and can be applied to many other exploited stocks.

P. lophotes Chace, 1985 Description. Rostrum remarkably curving dorsally, 1.5 times as long as carapace, dorsal margin with 14 teeth including 5���6 on carapace, all teeth on carapace with distinct basal sutures and movable, ventral margin with 13��� 18 teeth; abdomen smooth and rounded dorsally, pleura of fourth and fifth somites with small marginal tooth posteriorly sixth somite 1.5 times as long as maximum height; eye broadly subpyriform, maximum diameter about 0.2 carapace length; 3rd maxilliped overreaching distal margin of antennal scale by half of ultimate segment, with epipod, penultimate segment about 0.7 as long as ultimate segment; 2nd pereopods unequal with epipods, not extremely slender or thread-like, left overreaching antennal scale by distal 3 segment and anterior 0.3 of merus, with 147 carpal articles, right overreaching antennal scale by entire chela and anterior 0.7 of carpus, with 40 carpal articles (Kim et al. 2012). Distribution. Indo-West Pacific: Korea, Japan, Philippines, Vietnam and southern Arabia; at depths of 105��� 329 m (Kim et al. 2012)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 585, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Kim, J. N., Choi, J. H., Lee, J. H. & Kim, J. I. (2012) Six Pandalid Shrimps of the genus Plesionika (Crustacea: Decapoda: Caridea) in Korea. Animal Systematics, Evolution and Diversity, 28, 105 - 116."]}

P. unidens Bate, 1888 Description. Rostrum far overreaching antennal scale, armed dorsally with 7 or 8 teeth, including 3 on carapace posterior to level of orbital margin and 1 isolated in anterior 1/4 of rostrum, 3 posteriormost teeth with distinct basal sutures but none with barbed tips, armed ventrally with 10���20 teeth; abdomen with 3rd somite lacking posteromesial tooth but with median dorsal carina typically forming obtuse tooth anterior to posterior margin of somite; eye kidney-shaped, maximum diameter about 1/3 carapace length, ocellus obliquely oval, slightly constricted at junction with cornea; 3rd maxilliped with epipod, penultimate segment about 4/5 as long as terminal segment; 2nd pereopods very unequal with epipods, left one longer with more than 200 carpal articles, right with 33���36 (Chace 1985). Distribution. Bay of Bengal, South and East China seas, Japan, Philippines and Indonesia; at depths of 184��� 400m (Li 2006b)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 589, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Li, X. (2006 b) Report on some pandalid shrimps from the East China Sea (Decapoda, Caridea). Crustaceana, 79, 1281 - 1296. https: // doi. org / 10.1163 / 156854006779277303"]}

P. sindoi (Rathbun, 1906) Description. Rostrum 1.5 times as long as carapace, from the orbital margin the rostrum runs horizontally forward as far as the distal extremity of the antennular peduncle and from here it is a little and obliquely turned upward, 5 movable teeth on the carapace, lower margin is armed with 6 teeth; abdomen nearly 4-times as long as the carapace; the eyes are little more than one-fourth the length of the carapace and this diameter is slightly longer than the axial; external maxillipeds reach by their terminal joint and one-fourth of the penultimate beyond the antennal scale, exopodite small, not yet reaching to the middle of the antepenultimate joint; 1st pereopods reach by 4/5 their terminal joint (or propodus) beyond the external maxillepeds the penultimate joint or carpus is almost twice as long as the terminal, these joints being respectively 9.1 mm. and 5 mm. long in the adult female (Chace1985). Distribution. Japan, South China Sea, Philippines and Indonesia; at depths of 122���800 m (Li & Komai 2003)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 588, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Li, X. & Komai, T. (2003) Pandaloid shrimps from the northern South China Sea, with description of a new species of Plesionika (Crustacea: Decapoda: Caridea). Raffles Bulletin of Zoology, 51, 257 - 275."]}

P. alcocki (Anderson, 1896) Description. The rostrum is nearly 1.5 to 2.0 times of the carapace length, it is armed dorsally at its basal end with usually 5 teeth, three or four of which are movable and very small and stand close together on the gastric crest, with two large isolated ones just in front of them, ventrally it is armed throughout, beyond the antennular peduncle, with a series of distant teeth not concealed by setae to the number of from 4 to 8; the 6th abdominal tergum is not quite twice as long as the 5th; there is no distinct ocellus on the dorsal margin of the eye; 1st perepods are not shorter than the external maxillipeds, 2nd perepods in the male alone are very slightly unequal in length: one of them reaches almost to the other very slightly beyond the tips of the external maxillipeds (Alcock 1901). Distribution. Arabian Sea, off the south and south-west coast of India, Bay of Bengal, Andaman Sea, Indonesia, Japan and Philippines; at depths of 496���1092 m (Alcock 1901; Holthuis 1980; De Grave & Fransen 2011)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 580, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Alcock, A. (1901) A descriptive catalogue of Indian deep - sea Crustacea, Decapoda, Macrura and Anomala in the Indian Museum., Baptist Mission Press, Calcutta, India, 286 pp.","Holthuis, L. B. (1980) Shrimps and prawns of the world. An annotated catalogue of species of interest to fisheries. FAO Species Catalogue, Vol. 1. FAO Fisheries Synopsis, 125, 1 - 271.","DeGrave, S. & Fransen C. H. J. M. (2011) Carideorum Catalogus: the recent species of the dendrobranchiate, stenopodidean, procarididean and caridean shrimps (Crustacea: Decapoda). Zoologische Mededelingen, Leiden, 89, 195 - 589."]}

P. longidactylus Li & Komai, 2003 Description. Rostrum far overreaching antennal scale, 1.1–1.2 times as long as carapace, armed dorsally with 5 moderately large teeth, each with obscurely barbed tip and with 2 tiny subapical teeth, ventral margin with 10–13 teeth; 3rd abdominal somite not compressed dorsally, unarmed on posterodorsal margin; 3rd maxilliped with ultimate segment about 1.4 times as long as penultimate segment; 2nd pereopods greatly unequal with well developed strap-like epipod each bearing terminal hook, left with 25–30 carpal articles and right with 8 carpal articles (Li & Komai 2003). Distribution. Known only from South China Sea at depths of 55–144 m (Li 2006a).

P. heterocarpus (Costa, 1871) Description. Rostrum long, about two times as long as scaphopcerite, slender and slightly curved upward, dorsal margin with 15���23 teeth of which the proximal 4���6 are movable and situated behind the orbit, ventral margin bears 16���23 teeth; posterior part of the 3rd abdominal somite is slightly concave; eye with maximum diameter about l/5 of carapace length, ocellus longitudinally oval, constricted at juncture with cornea; 3rd maxilliped with well developed strap-like epipod, penultimate segment sub-equal to terminal segment; 2nd pair of pereiopod distinctly unequal, left one much longer than the right one, overreaching scaphocerite with chela, carpus and distal half of merus, with 107���215 carpal segments, 80���111 meral segments and about 25 ischial segments (Holthuis 1980). Distribution. Cyprus, Israel, Syria and Turkey; at depths of 10���850 m (Holthuis 1980)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 583, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Holthuis, L. B. (1980) Shrimps and prawns of the world. An annotated catalogue of species of interest to fisheries. FAO Species Catalogue, Vol. 1. FAO Fisheries Synopsis, 125, 1 - 271."]}

P. hypanodon Doflein, 1902 Description. Rostrum is only half as long as the carapace and quite straight, except for the tip, which is bent upwards, dorsal margin with 7 teeth, the anterior three are behind the eye basis, smaller and stand narrower to each other than the other 4, which are arranged in similar distances towards the tip, ventral margin is smooth and without teeth; abdomen is smooth, compressed, and the hindmargin of the third segment is slightly recessed; eyes are spherical-shaped, semi-large with distinct ocellus; 2nd pereiopods equally long and slender with 15 carpal articles (Doflein 1902). Distribution. Known only from Sagami Bay, Japan (Doflein 1902)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 583, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Doflein, F. (1902) Ostasiatische Dekapoden. Abhandlungen der Bayerischen Akademie der Wissenschaften, Munchen, 21, 613 - 670."]}

P. hsuehyui Chan, 2004 Description. Rostrum 1.3���2.0 times as long as carapace, bending downwards near base but recurved upwards after passing eyes, dorsal rostrum proper unarmed except for 2 small subapical teeth, ventral rostrum generally bearing 9 or 10 teeth; abdominal 3rd somite slightly arched dorsally; 3rd maxilliped overreaching scaphocerite by up to 2/3 length of distal segment, distal segment 1.4���1.8 times as long as penultimate segment; 2nd pereopods bearing 15��� 22 carpal articles on right side and 53���70 carpal articles on left side, shorter one exceeding scaphocerite by about half chela (Chan 2004). Distribution. Taiwan and Philippines; at depths of 115���300 m (Chan 2004)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 583, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chan, T. Y. (2004) The \" Plesionika rostricrescentis (Bate, 1888) \" and \" P. lophotes Chace, 1985 \" species groups of Plesionika Bate, 1888, with descriptions of five new species (Crustacea: Decapoda: Pandalidae), in Marshall B. & Richer De Forges B. (eds), Tropical deep-sea benthos, vol. 23. Memoires du Museum national d'Histoire naturelle, Paris, 191, 293 - 318."]}

P. taiwanica Chan & Yu, 2000 Description. Rostrum 1.3–2.1 times as long as carapace, slightly curving downward at basal part but gently recurved upwards and straight after passing antennular peduncle, dorsal border generally armed with 6–8 teeth, with posterior 4–6 teeth restricted at basal part and forming a low crest while the anterior 1–3 teeth located anterior to level of antennular peduncle, lower border densely serrated with 22–38 small teeth; abdominal 3rd somite feebly arched dorsally and with posterior margin convex; eye subspherical and probably bearing indistinct ocellus; 3rd maxilliped bearing well developed epipod and long strip-like exopod, penultimate segment 1.2–1.5 times as long as distal segment, overreaching scaphocerite by 1/3 to almost entire distal segment; 2nd pereiopods subequal with well developed epipod, bearing 16–25 carpal articles (Chan & Yu 2000). Distribution. Known only from Taiwan at depths of 150–300 m (Chan & Yu 2000).

P. edwardsii (Brandt, 1851) Description. Rostrum curved downward in basal region, then strongly curved upwards beyond antennular peduncle, slightly more than 2 times as long as carapace, armed dorsally with 28���36 teeth over entire length, anterior teeth closely spaced, posterior teeth larger and well spaced, ventral border bearing 37���52 closely spaced teeth; dorsal surface of abdominal 3rd somite slightly arched but not sharply angular; eye large and subspherical, with distinct ocellus; 3rd maxilliped with distal two segments subequal, bearing rudimentary epipod; 2nd Pereiopods subequal with 18���28 carpal articles (Chace 1985). Distribution. Indo-Pacific, Indonesia, Philippines and Taiwan; at depths of 50���680 m (Chace 1985). P. ensis (Milne-Edwards, 1881) Description. Rostrum nearly 1.6 to 2 times of the carapace length, armed dorsally with 5 or 6 teeth, three or four close together, two isolated anteriorly, ventrally it is closely and evenly serrated, the teeth are fixed; the posterior border of the 3rd abdominal tergum is acutely produced in the middle line to form a spine; the ocellus is distinct but not independent; the external maxillipeds with well-developed exopodite, little longer and stouter than the 1st pair of pereopods, reach a short way beyond the tip of the antennal scale (Alcock 1901). Distribution. Arabian Sea, Bay of Bengal and Andaman Sea; at depths of 250���400 m (Alcock 1901)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 582, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Alcock, A. (1901) A descriptive catalogue of Indian deep - sea Crustacea, Decapoda, Macrura and Anomala in the Indian Museum., Baptist Mission Press, Calcutta, India, 286 pp."]}

P. spinensis Chace, 1985 Description. Rostrum far overreaching antennal scale, armed dorsally throughout length with 13���24 teeth, including 2 or 3 on carapace posterior to level of orbital margin, posteriormost tooth with faint, incomplete basal suture, none with barbed tips, armed ventrally with 2539 teeth; abdomen typically with posteromesial tooth but without median dorsal carina on 3rd somite; eye very broadly subpyriform, maximum diameter nearly or quite 1/3 carapace length, ocellus subcircular, somewhat constricted at juncture with cornea; 3rd maxilliped with epipod, penultimate segment slightly shorter or longer than terminal segment; 2nd pereopods subequal with welldeveloped epipod, bearing 14���23 carpal articles (Chace 1985). Distribution. South China Sea and Philippines; at depths of 199���472 m (Li 2006a), Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 588, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Li, X. (2006 a) Additional Pandalid shrimps from the South China Sea (Crustacea: Decapoda: Caridea), with description of a new species. Raffles Bulletin of Zoology, 54, 361 - 372."]}

P. indica De Man, 1917 Description. Rostrum 1.8 times as long as carapace, far overreaching antennal scale, armed dorsally throughout length with 27���33 teeth, including 4���6 on carapace posterior to level of orbital margin, 2���4 posteriormost teeth with distinct basal suture but none with barbed tips, armed ventrally with 22���27 teeth; abdomen without posteromesial tooth or median dorsal carina on 3rd somite; eye subpyriform, maximum diameter fully 1/6 carapace length, ocellus prominent, somewhat constricted at juncture with cornea; 3rd maxilliped with epipod, penultimate segment 1.2���1.4 times as long as terminal segment; 2nd pereopods subequal with prominent epipods, bearing 31��� 34 carpal articles (De Man 1920; Chace 1985). Distribution. Indonesia, South China Sea, Philippines and Japan; at depths of 238��� 472 m. (Li & Komai 2003)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 583, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411","Li, X. & Komai, T. (2003) Pandaloid shrimps from the northern South China Sea, with description of a new species of Plesionika (Crustacea: Decapoda: Caridea). Raffles Bulletin of Zoology, 51, 257 - 275."]}

P. fimbriata Chace, 1985 Description. Rostrum far overreaching antennal scale, armed dorsally throughout length with 11���14 teeth, including 3 or 4 on carapace posterior to level of orbital margin, 2���4 posteriormost teeth with distinct basal sutures but none with barbed tips, armed ventrally with 5���8 teeth; abdomen without posteromesial tooth or median dorsal carina on 3rd somite; eye broadly subpyriform, maximum diameter about one-fourth carapace length, ocellus large, subcircular, in broad contact with cornea; 3rd maxilliped with epipod, penultimate segment 1.2���1.5 times as long as terminal segment; 2nd peropods subequal with epipod, bearing 18���30 carpal articles (Chace 1985). Distribution. Known only from the Philippines at depths of 95���250 m (Chace 1985)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 582, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chace, F. A. Jr. (1985) The caridean shrimps (Crustcea: Decapoda) of the Albatross Philippine Expedition, 1907 - 1910, Part 3: Families Thalassocarididae and Pandalidae. Smithsonian Contributions to Zoology, 411, 1 - 143. https: // doi. org / 10.5479 / si. 00810282.411"]}

P. erythrocyclus Chan & Crosnier, 1997 Description. Rostrum more or less as long as carapace and just overreaching scaphocerite, curving downward at base but abruptly upturned after passing the eye, dorsal border with only 2 small apical teeth and 1���2 fixed basal teeth above eye, ventral border with 7���9 evenly distributed teeth between level of eye and tip; eye subspherical and bearing distinct ocellus; 3rd maxilliped bearing well developed epipod and a long exopod, with penultimate segment 0.6���0.7 times as long as distal segment, overreaching scaphocerite by 1/3���1/2 of distal segment; 2nd pereiopods bearing 20���22 carpal articles on the right side and 76���83 carpal articles on the left side (Chan & Crosnier 1997). Distribution. Known only from Taiwan at depths of 267���360 m (Chan 2004)., Published as part of Ahamed, Ferdous, Cardoso, Irene A., Ahmed, Zoarder F., Hossain, Md. Y. & Ohtomi, Jun, 2017, An overview of the genus Plesionika Bate, 1888 (Decapoda, Caridea, Pandalidae) in Asian waters, pp. 575-593 in Zootaxa 4221 (5) on page 582, DOI: 10.11646/zootaxa.4221.5.6, http://zenodo.org/record/253575, {"references":["Chan, T. Y. & Crosnier, A. (1997) Crustacea Decapoda: deep - sea shrimps of the genus Plesionika Bate, 1888 (Pandalidae) from French Polynesia, with descriptions of five new species. In: A. Crosnier (ed.), Resultats des Campagnes MUSORSTOM, 18. Memoires du Museum national d'Histoire naturelle, Paris, (A) 176, 187 - 234.","Chan, T. Y. (2004) The \" Plesionika rostricrescentis (Bate, 1888) \" and \" P. lophotes Chace, 1985 \" species groups of Plesionika Bate, 1888, with descriptions of five new species (Crustacea: Decapoda: Pandalidae), in Marshall B. & Richer De Forges B. (eds), Tropical deep-sea benthos, vol. 23. Memoires du Museum national d'Histoire naturelle, Paris, 191, 293 - 318."]}

The morphology of the decapodid stage of Plesionika narval (Fabricius, 1787) is described and illustrated based on larvae collected in the Canary Islands waters (NW Africa). Mitochondrial DNA analysis of the barcoding gene COI sequences confirmed the identity of the larvae specimens. Decapodid development of P. narval is compared with other pandalid and related genera Pandalus, Pandalopsis, Procletes, Stylopandalus, and Icotopus. Based on their morphological similarities we concluded that the nomina dubia genus Icotopus is a synonym of Plesionika and herein selected Plesionika over Icotopus as the valid name for the genus.

The population dynamics of Pandalus gracilis was investigated in the southeastern coastal area of Korea between May 1998 and April 2000. Of the 4,127 specimens, 57% were identified as females, 39% as males, and 4% as transitional hermaphrodites. The number of females was greater than that of males and transexuals. A significant correlation was observed between the number of transitional hermaphrodites and ambient seawater temperature. Growth parameters were estimated using the modified von Bertalanffy growth function model incorporating seasonal variation in growth using the program ELEFAN. Females grew faster and reached a larger sizeat-age than males (K=0.65/y and L∞=17.86 mm carapace length [CL] for females; K=0.51/y and L∞=14.70 mm CL for males). Mean size and age (95% confidence limits) at sex transition, calculated from growth parameters, were 7.07 mm carapace length and 1.05 years, respectively. The reproductive strategies of pandalid shrimps are discussed in terms of the type of sex transition.

Endosulfan is a neurotoxic organochlorine insecticide of the cyclodiene family of pesticides that inhibits molting and reproduction in aquatic crustaceans. In order to determine the molecular mechanism of endosulfan as an endocrine disrupting chemical (EDC), differential display RT-PCR (DDRT-PCR) was used to isolate genes in the shrimp, Pandalopsis japonica , affected by endosulfan exposure. PCR screening of cDNA from the hepatopancreas from control and endosulfan-exposed animals, using 120 sets of random primers, yielded partial cDNAs encoding two vitellogenin-like proteins (Pj-Vg1 and -Vg2). Complete sequences were obtained using a combination of RT-PCR and RACE-PCR. Pj-Vg1 (7883 bp) encoded a protein composed of 2533 amino acid residues (283.27 kDa estimated mass), whereas Pj-Vg2 (7792 bp) encoded a protein composed of 2537 amino acids residues (284.87 kDa estimated mass). Alignment of the Pj-Vgs with those of other vitellogenins identified a conserved subtilisin cleavage site (RQKR) and the lipoprotein N-terminal (vitellin), DUF1081, and von Willebrand factor type D domains, indicating both genes encoded functional proteins. Phylogenetic analysis showed that Pj-Vg1 and -Vg2 were most similar to Pandalus hypsinotus Vg. Both Pj-Vg1 and -Vg2 were expressed primarily in the hepatopancreas, although the Pj-Vg2 transcript was also detected in the ovary. The effects of the 3-day endosulfan exposure (2.5 µg/L and 25 µg/L) on Vg expression in the hepatopancreas were determined by quantitative RT-PCR. Expression of both transcripts was significantly inhibited at 25 µg/L suggesting that Pj-Vgs can be used as indicator for endosulfan exposure.

[The population dynamics of Pandalus gracilis were investigated in the southeast coastal area of Korea, between May 1998 and April 2000. The number of females was greater than that of males and of intersexes. Based on dry weight of egg masses at the early stage, the reproductive output averaged 34% of female weight. A higher gonadosomatic index (GSI) was observed from December to June. Ovigerous females occurred from December to September. During the incubation period, the egg volume significantly increased and brood loss of eggs occurred. A significant difference in ovarian weight between females with early eggs and late egg stages was found. This indicates that ovarian maturation occurs during the incubation time, suggesting that females are potentially consecutive breeders, capable of multiple spawnings during a reproductive season. Spawning by a single female seems to occur consecutively in a single reproductive period. Female maturity was determined by the frequency of both ovigerous females and females with a maturing ovary. The size at 50% sexual maturity (CL50) was estimated as 9.2 mm. The size distribution in the population was similar in the two years of this study. La dynamique des populations de Pandalus gracilis a ete etudiee dans la zone cotiere sudorientale de la Coree, entre mai 1998 et avril 2000. Le nombre de femelles etait plus eleve que celui des mâles et des animaux intersexues. A partir du poids sec des oeufs au premier stade, la production etait en moyenne 34% du poids de la femelle. Un index gonado-somatique (GSI) plus eleve a ete observe de decembre a juin. Les femelles ovigeres etaient presentes de decembre a septembre. Au cours de la periode d'incubation, le volume de l'œuf augmentait significativement et la perte des œufs a ete observee. Une difference significative du poids de l'ovaire entre femelles a œufs aux premiers stades et femelles a œufs plus avances a ete trouvee. Ceci indique que la maturation de l'ovaire intervient pendant la periode d'incubation, suggerant que les femelles ont potentiellement des productions d'œufs successives, et sont capables de pontes multiples au cours d'une saison de reproduction. La ponte chez une femelle semble se produire plusieurs fois a la suite au cours d'une periode de reproduction. La maturite de la femelle etait determinee par la frequence a la fois des femelles ovigeres et des femelles presentant un ovaire en cours de maturation. La taille a 50% de maturite sexuelle, (CL50) a ete estimee a 9,2 mm. La distribution de taille dans la population etait analogue au long des deux annees qu'a dure cette etude., The population dynamics of Pandalus gracilis were investigated in the southeast coastal area of Korea, between May 1998 and April 2000. The number of females was greater than that of males and of intersexes. Based on dry weight of egg masses at the early stage, the reproductive output averaged 34% of female weight. A higher gonadosomatic index (GSI) was observed from December to June. Ovigerous females occurred from December to September. During the incubation period, the egg volume significantly increased and brood loss of eggs occurred. A significant difference in ovarian weight between females with early eggs and late egg stages was found. This indicates that ovarian maturation occurs during the incubation time, suggesting that females are potentially consecutive breeders, capable of multiple spawnings during a reproductive season. Spawning by a single female seems to occur consecutively in a single reproductive period. Female maturity was determined by the frequency of both ovigerous females and females with a maturing ovary. The size at 50% sexual maturity (CL50) was estimated as 9.2 mm. The size distribution in the population was similar in the two years of this study. La dynamique des populations de Pandalus gracilis a ete etudiee dans la zone cotiere sudorientale de la Coree, entre mai 1998 et avril 2000. Le nombre de femelles etait plus eleve que celui des mâles et des animaux intersexues. A partir du poids sec des oeufs au premier stade, la production etait en moyenne 34% du poids de la femelle. Un index gonado-somatique (GSI) plus eleve a ete observe de decembre a juin. Les femelles ovigeres etaient presentes de decembre a septembre. Au cours de la periode d'incubation, le volume de l'œuf augmentait significativement et la perte des œufs a ete observee. Une difference significative du poids de l'ovaire entre femelles a œufs aux premiers stades et femelles a œufs plus avances a ete trouvee. Ceci indique que la maturation de l'ovaire intervient pendant la periode d'incubation, suggerant que les femelles ont potentiellement des productions d'œufs successives, et sont capables de pontes multiples au cours d'une saison de reproduction. La ponte chez une femelle semble se produire plusieurs fois a la suite au cours d'une periode de reproduction. La maturite de la femelle etait determinee par la frequence a la fois des femelles ovigeres et des femelles presentant un ovaire en cours de maturation. La taille a 50% de maturite sexuelle, (CL50) a ete estimee a 9,2 mm. La distribution de taille dans la population etait analogue au long des deux annees qu'a dure cette etude.]

The concentrations of Fe, Zn, Cu, Cd, Mn, Pb, and Ni were determined in the hepatopancreas, muscle tissue, and carapace of the grass shrimp Pandalus kessleri from the coastal waters of the Lesser Kurilskaya Ridge. Sex reversal of the grass shrimp, which is a proterandrous hermaphrodite, had a marked influence on the concentrations of such metals as Fe, Cu, Cd, and Mn. The levels of Cd in the hepatopancreas of grass shrimp exceeded maximum permissible concentrations for seafood at all the stations studied. The main factors determining the metal levels in P. kessleri from the investigated locations are discussed.

The family Pandalidae has a cosmopolitan distribution, occurring from the coastal region to more than 3000 meters of depth, and includes some species of economic importance. Three genera occur from Brazil: Heterocarpus A. Milne Edwards, 1881, Plesionika Bate, 1888 and Pandalus Leach, 1814. During the collections of the Programa de Avaliação dos Recursos Vivos da Zona Econômica Exclusiva of Brazil (REVIZEE, Northeast Score) a male of Heterocarpus laevigatus was collected in Pernambuco State, at a depth of 500m and fourteen females and four males of Plesionika escatilis were collected off the States of Pernambuco, Alagoas and Bahia, in depths varying from 93 to 260m. These records supplement the information on the distribution of these species, and represent the first records of H. laevigatus and P. escatilis from the Atlantic coast of South America.

We determined the absolute (AIF) and relative (RIF) individual fecundity in a commercially important object, the grass shrimp, Pandalus kessleri (Decapoda: Pandalidae) near the Southern Kuril Islands. In the shrimps from Izmeny Bay (Kunashir Island) and the coastal area of the Southern Kuril Islands, the AIF equaled 192–918 (averaging 505) and 162–784 (459), respectively. In larger females, the AIF increases, reaches the maximum value, and then decreases again in the largest females. In June the AIF is smaller than in September, and in larger prawns, this difference is more pronounced. The mean large (D) and small (d) diameters of eggs equaled 1972 (1665–2400) and 1538 (1347–1900) μm, respectively; the D/d ratio equaled 1.28. The mean wet weight of an egg (w) was 3.43 mg (1.986–4.9) mg. From September 1 to November 30 D and d increased from 1894 to 2088 μm and from 1490 to 1567 μm, respectively. The factors affecting the fecundity of grass shrimp in Izmeny Bay are discussed.

Pandalus tridens Rathbun, 1902 (Fig. 26B–D) Pandalus montagui tridens Rathbun, 1902a: 901; 1904: 41. — Schmitt 1921: 42, pl. 13, fig. 2. — Kozloff 1974: 163. — Word & Charwat 1976: 185. Pandalus tridens. — Butler 1980: 137, pl. 8B (extensive discussion of nomenclature). — Wicksten 1989b: 313. — Jensen 1995: 55, fig. 104. Diagnosis. Body moderately stout, shell thin, surface smooth. Length of rostrum 1.3–1.8 times carapace length, distal half slightly ascending, with 9–13 dorsal spines, teeth; 6–8 ventral teeth; no dorsal teeth on distal half, apex bifid or trifid. Carapace with pterygostomian, antennal teeth. Eyes large. First antenna with short stylocerite, length of flagella extending beyond rostrum by about 0.3 times their lengths. Second antenna with scaphocerite reaching middle of rostrum, scaphocerite narrow with lateral tooth slightly exceeding blade, basicerite with weak lower tooth, flagellum longer than body. Third maxilliped with slight lamina on antepenultimate segment, epipod present. Pereopods 1–4 with epipods. Pereopod 1 chelate. Pereopods 2 unequal, left longer with about 74 carpal articles; right shorter with 20–28 articles. Pereopods 3–5 with 5–7 spinules on dactyl, propodus with 15–32 spinules, carpus with 2–4 spines, merus with 4–7 spines, ischium with 0–1 spine, decreasing in number from pereopod 3–5. Posterior margin of abdominal somite 3 with moderate projection. Pleuron of somite 4 with weak ventral point, posterolateral margin of somite 5 with strong point. Somite 6 shorter than telson. Telson with 5 pair dorsolateral spines. Male total length to 83 mm, female to 123 mm. Color in life. Fine red dots over translucent backgroun. Red blotches, bands on pereopods, yellow blotches on pereopods 3–5, third maxilliped with yellow apex. Antennal flagellum with alternate red, transparent bands, flagella of first antenna with red, white bands (Butler 1980, color plate 8B). Habitat and depth. Rocky areas, 5–1984 m. Range. Cape Oyutorsky, Pribilof Is. to San Nicolas I., California, but few records south of Washington state. Type locality off North Head, Akutan I., Alaska. Remarks. Pandalus tridens has been caught commercially off British Columbia. It has been reported southwest of the Colombia River (McCauley 1972, as P. montagui tridens) and off Point Arena and San Nicolas I. in California (Schmitt 1921). Most recent records are from Puget Sound northward., Published as part of Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, pp. 1-307 in Zootaxa 3371 on page 104, {"references":["Rathbun, M. J. (1902 a) Descriptions of new decapod crustaceans from the west coast of North America. Proceedings of the United States National Museum, 24, 885 - 905.","Rathbun, M. J. (1904) Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10, 1 - 219.","Schmitt, W. L. (1921) The marine decapod Crustacea of California. University of California Publications in Zoology, 23, 1 - 470.","Kozloff, E. N. (1974) Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. University of Washington Press, Seattle, 226 pp.","Word, J. & Charwat, D. (1976) Invertebrates of Southern California Coastal Waters. II. Natantia. Southern California Coastal Water Research Project, El Segundo, California. 238 pp.","Butler, T. H. (1980) Shrimps of the Pacific Coast of Canada. Canadian Bulletin of Fisheries and Aquatic Science, 202, 1 - 280.","Wicksten, M. K. (1989 b) Ranges of offshore decapod crustaceans in the eastern Pacific Ocean. Transactions of the San Diego Society of Natural History, 21, 291 - 316.","Jensen, G. C. (1995) Pacific Coast Crabs and Shrimps. Sea Challengers, Monterey, California, 87 pp.","McCauley, J. E. (1972) A preliminary checklist of selected groups of invertebrates from otter-trawl and dredge collections off Oregon. In: Pruter, A. T. & Alverson, D. L. (Eds.) The Columbia River Estuary and Adjacent Ocean Waters. Bioenvironmental Studies. University of Washington Press, Seattle, pp. 409 - 443."]}

Pandalus danae Stimpson, 1857 (Fig. 25C–E, Pl. 4 C) Pandalus danae Stimpson, 1857a: 87. — Holmes 1900: 209, pl. 4, figs. 61–62. — Rathbun 1904: 47, fig. 13. — Schmitt 1921: 44, fig. 25, pl. 13, fig. 3. — Johnson & Snook 1927: 302, fig. 257 a, c. — MacGinitie & MacGinitie 1968: 272. — Kozloff 1974: 163. — Word & Charwat 1976: 179. — Butler 1980: 147. pl. 4A. — Ricketts et al. 1985: 352. — Jensen & Armstrong 1987: 216. — Wicksten 1991: 812. — Jensen 1995: 53, fig. 98. — Kuris et al. 2007: 637. Pandalus gurneyi Stimpson, 1871: 128. — Rathbun 1904: 50. — Schmitt 1921: 46, pl. 13, fig. 1. — Johnson & Snook 1927: 303, fig. 257b. — Word & Charwat 1976: 181. — Hendrickx & Wicksten 1989: 83, fig. 8C, D. Pandalus franciscorum Kingsley, 1878b: 94. Diagnosis. Rostrum 1.0–1.6 times as long as carapace, nearly straight to sharply upcurved, with 10–15 dorsal teeth, spines; 6–12 ventral teeth, apex trifid. Eye large. Stylocerite of first antennae short, flagella shorter than carapace. Scaphocerite narrow, lateral tooth exceeding blade, flagellum about equal to body length. Carapace with antennal, pterygostomian teeth. Third maxilliped without exopod but with epipod. Pereopods 1–4 with epipods. Pereopod 1 slender, chelate; ischium with slight lamina. Pereopods 2 unequal, left with about 60 carpal articles, right with 18–21 articles, epipods on pereopods 1–4. Pereopods 3–5 slender, margins spinulose, with 6–9 meral spines. Dorsal posterior margin of abdominal somite 3 slightly produced. Pleuron of somite 4 with weak posterolateral point, pleuron of somite 5 with strong posterolateral point. Somite 6 shorter than telson. Telson with 5 or 6 pairs dorsolateral spines, 2 pair terminal spines. Male total length to 123 mm, female to 140 mm. Color in life. Background translucent, marked with irregular striping, spots of brick red or chocolate brown, with fine brick-red dots between stripes. Fine blue spots on cardiac region of carapace. Antennae and appendages marked with striking bands of white, yellow, red or brown (Butler 1980, color plate 4A; Wicksten 1991). Habitat and depth. Sea grass beds, rocky reefs, mixed shell, sand; lowest intertidal zone to 185 m. Range. Black Hills, north side of Alaskan Peninsula, Alaska to San Quintin Bay, Baja California. Type locality Puget Sound. Remarks. These shrimp often are seen in cracks or near rocks during the day, where they may rest upside down. The long, banded antennae are conspicuous. These shrimp will pick at a diver's equipment or even a gloved hand, but do not show any obvious quivering of the antennae or waving the body, as is seen in tropical cleaner shrimps of the genus Lysmata (Wicksten 2009). Confusion remains as to whether or not P. danae and P. gurneyi are separate species., Published as part of Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, pp. 1-307 in Zootaxa 3371 on pages 100-101, {"references":["Stimpson, W. (1857 a) Notices of new species of Crustacea in western North America being an abstract from a paper to be published in the Journal of the Society. Proceedings of the Boston Society of Natural History, 6, 84 - 89.","Holmes, S. J. (1900) Synopsis of California stalk-eyed Crustacea. Occasional Papers of the California Academy of Sciences, 7, 12 - 62.","Rathbun, M. J. (1904) Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10, 1 - 219.","Schmitt, W. L. (1921) The marine decapod Crustacea of California. University of California Publications in Zoology, 23, 1 - 470.","Johnson, M. E. & Snook, H. J. (1927) Seashore Animals of the Pacific Coast. Dover Publications, New York, reprint 1967, 659 pp.","MacGinitie, G. E. & MacGinitie, N. (1968) Natural History of Marine Animals. McGraw-Hill, NewYork, second ed., 523 pp.","Kozloff, E. N. (1974) Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. University of Washington Press, Seattle, 226 pp.","Word, J. & Charwat, D. (1976) Invertebrates of Southern California Coastal Waters. II. Natantia. Southern California Coastal Water Research Project, El Segundo, California. 238 pp.","Butler, T. H. (1980) Shrimps of the Pacific Coast of Canada. Canadian Bulletin of Fisheries and Aquatic Science, 202, 1 - 280.","Ricketts, E. F., Calvin, J., Hedgpeth, J. W. & Phillips, D. W. (1985) Between Pacific Tides. Stanford University Press, Stanford, California, 5 th ed., 652 pp.","Jensen, G. C. & Armstrong, D. A. (1987) Range extensions of some northeastern Pacific Decapoda. Crustaceana, 52, 215 - 217.","Wicksten, M. K. (1991) Pandalus gurneyi Stimpson synonymized with Pandalus danae Stimpson (Decapoda: Pandalidae). Proceedings of the Biological Society of Washington, 104, 812 - 815.","Jensen, G. C. (1995) Pacific Coast Crabs and Shrimps. Sea Challengers, Monterey, California, 87 pp.","Kuris, A. M., Sadeghian, P. & Carlton, J. T. (2007) Keys to Decapod Crustacea. In: Carlton, J. T. (Ed.) The Light and Smith Manual: Intertidal Invertebrates Central California to Oregon. University of California Press, Berkeley, 4 th ed., pp. 636 - 656.","Stimpson, W. (1871) Notes on North American Crustacea, in the museum of the Smithsonian Institution. No. III. Annals of the Lyceum of Natural History, New York, 10, 921 - 936.","Hendrickx, M. E. & Wicksten, M. K. (1989) Los Pandalidae (Crustacea: Caridea) del Pacifico mexicano, con una clave para su identificacion. Caldasia, 16, 71 - 86.","Kingsley, J. S. (1878 b) Notes on the North American Caridea in the Museum of the Peabody Academy of Science at Salem, Mass. Proceedings of the Academy of Natural Sciences of Philadelphia, 30, 89 - 98.","Wicksten, M. K. (2009) Interactions with fishes of five species of Lysmata (Decapoda, Caridea, Lysmatidae). Crustaceana, 82, 1213 - 1223."]}

Pandalus stenolepis Rathbun, 1902 (Fig. 25J–L) Pandalus stenolepis Rathbun, 1902a: 901; 1904: 49, fig. 14. — Johnson & Snook 1927: 303, fig. 257c. — Kozloff 1974: 163. — Butler l980: 145, pl. 2C. — Wicksten 1989b: 313. — Jensen 1995: 55, fig. 103. Diagnosis. Body stout. Rostrum with distal 0.66 ascending sharply, 8–12 dorsal teeth, spines; 5–7 ventral teeth, apex bifid. Carapace with strong antennal, moderate to weak pterygostomian teeth, patch of pubescence on cardiac region. Eyes large, cornea almost spherical. Antennular peduncle short, stylocerite short, round. Scaphocerite narrow, lateral tooth exceeding blade, peduncle short. Third maxilliped moderately stout, antepenultimate segment with slight lamina, epipod present. Pereopods 1–4 with epipods. Pereopod 1 slender, ischium with slight lamina. Pereopod 2 chelate, left leg longer, more slender than right, carpus with about 50 articles; carpus of right leg with l0–13 articles. Pereopod 3 moderately stout, with 0 or l ischial spines, merus with 5–7 spines, carpus with 1 or 2 spines, propodus with l8–22 spinules, dactyl stout, spinose. Pereopod 4 about as stout as third pereopod, with 1 ischial spine, 5–7 meral spines, carpus with l–2 spines, propodus with 14–18 spinules, stout dactyl. Pereopod 5 with 0 or 1 meral spine, merus with 3–5 spines, carpus with 2 spines, propodus with 15–23 spinules, stout dactyl. Abdominal somite 2 with distinct transverse dorsal sulcus, somite 3 with dorsal posterior margin moderately produced. Pleuron of somite 4 with weak ventral point, somite 5 with strong posterolateral point, somite 6 with moderate posteroventral point. Telson moderately wide, tapering to blunt apex, with 4–5 pairs dorsolateral spines. Male total length about 76 mm, female 82 mm. Color in life. Grayish to whitish, with patches of red on carapace, abdomen, appendages; blue dots on abdominal somites. Habitat and depth. Muddy bottoms, 49–229 m. Range. Unalaska I. to Hecata Bank, Oregon. Type locality Strait of Juan de Fuca., Published as part of Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, pp. 1-307 in Zootaxa 3371 on pages 103-104, {"references":["Rathbun, M. J. (1902 a) Descriptions of new decapod crustaceans from the west coast of North America. Proceedings of the United States National Museum, 24, 885 - 905.","Rathbun, M. J. (1904) Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10, 1 - 219.","Johnson, M. E. & Snook, H. J. (1927) Seashore Animals of the Pacific Coast. Dover Publications, New York, reprint 1967, 659 pp.","Kozloff, E. N. (1974) Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. University of Washington Press, Seattle, 226 pp.","Wicksten, M. K. (1989 b) Ranges of offshore decapod crustaceans in the eastern Pacific Ocean. Transactions of the San Diego Society of Natural History, 21, 291 - 316.","Jensen, G. C. (1995) Pacific Coast Crabs and Shrimps. Sea Challengers, Monterey, California, 87 pp."]}

Pandalus jordani Rathbun, 1902 (Fig. 25 F) Pandalus jordani Rathbun, 1902a: 900; 1904: 40. — Schmitt 1921: 41, pl. 14, fig. 1. — Kozloff 1974: 163. — Word & Charwat 1976: 183. — Butler 1980: 133, pl. 4D. — Wicksten 1989b: 313. Diagnosis. Body slender, surface smooth. Rostrum as long as carapace, with 4–17 dorsal spines, teeth; 7–10 ventral teeth, apex acute or bifid. Eye large. Stylocerite of first antennae short, both flagella longer than carapace. Length of scaphocerite of second antenna about half length of rostrum length, lateral tooth, blade equal; basicerite with moderate upper lateral, strong lower spines, flagellum longer than body. Third maxilliped with antepenultimate segment having slight lamina, epipod present. Pereopods 1–4 with epipods. Pereopod 1 slender, proximal end of merus with slight lamina. Pereopods 2 unequal, left longer, with 58–62 articles; right shorter, with 19–22 articles. Pereopods 3–5 slender, with slender dactyls bearing 4–7 spinules, propodus with 8–23 spinules, carpus with 2 or 3 spines, merus with 7–11 spines, ischium with 0 or 1 spine, decreasing in number from pereopod 3–5. Abdominal somite 3 with dorsal posterior part compressed, with carina. Posterolateral margin of pleuron 4 with moderate ventral point, pleuron of somite 5 with strong posterolateral point. Somite 6 shorter than telson. Telson with 8–13 pairs dorsolateral spines, 3 pairs distal spines. Male total length to 125 mm, female to 175 mm. Color in life. Fine red dots on translucent grayish background. Proximal part of antennal flagellum pale pink (Butler 1980). Habitat and depth. Offshore green mud or mixed sand, 36–457 m. Range. Iliuliuk Harbor, Unalaska I. to San Nicolas I., California. Type locality off Santa Cruz I., California. Remarks. Pandalus jordani is fished from Vancouver I. to Morro Bay, California, but the highest population density is off central Oregon. Catches are highest at 110– 183 m., Published as part of Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, pp. 1-307 in Zootaxa 3371 on page 101, {"references":["Rathbun, M. J. (1902 a) Descriptions of new decapod crustaceans from the west coast of North America. Proceedings of the United States National Museum, 24, 885 - 905.","Rathbun, M. J. (1904) Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10, 1 - 219.","Schmitt, W. L. (1921) The marine decapod Crustacea of California. University of California Publications in Zoology, 23, 1 - 470.","Kozloff, E. N. (1974) Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. University of Washington Press, Seattle, 226 pp.","Word, J. & Charwat, D. (1976) Invertebrates of Southern California Coastal Waters. II. Natantia. Southern California Coastal Water Research Project, El Segundo, California. 238 pp.","Butler, T. H. (1980) Shrimps of the Pacific Coast of Canada. Canadian Bulletin of Fisheries and Aquatic Science, 202, 1 - 280.","Wicksten, M. K. (1989 b) Ranges of offshore decapod crustaceans in the eastern Pacific Ocean. Transactions of the San Diego Society of Natural History, 21, 291 - 316."]}

Pandalus platyceros Brandt,1851 (Fig. 25G–I, Pl. 4D) Pandalus platyceros Brandt, 1851: 123. — Holmes 1900: 210. — Rathbun 1904: 44. — Schmitt 1921: 43, pl. 14, fig. 3. — Kozloff 1974: 163. — Word & Charwat 1976: 187. — Butler 1980: 139, pl. 2A. — Wicksten 1980c: 364; 1989b: 313. — Jensen 1995: 55, fig. 102. Pandalus pubescentulus Dana, 1852: 24. — Stimpson 1857b: 501. — Kingsley 1878b: 63. Diagnosis. Body stout, carapace pubescent. Length of rostrum 1.2–2.0 times carapace length, with 4–17 dorsal spines, teeth; 6–8 ventral rostral teeth, usually one tooth dorsal, proximal to rostral apex. Carapace with antennal, pterygostomian teeth. Eye large. First antenna with short stylocerite, inner flagellum longer than outer, both longer than carapace. Length of scaphocerite slightly longer than 0.5 times rostrum length, spine slightly exceeding blade, basicerite with moderate upper lateral spine, strong lower spine, flagellum equaling or exceeding body length. Third maxilliped stout, antepenultimate segment with slight lamina, epipod present. Pereopods 1–4 with epipods. Pereopod 1 with minute chela, ischium with slight lamella. Pereopods 2 chelate, left longer than right, left with 27–31 articles, right with 8 or 9 articles. Pereopods 3–5 with dactyls having 4–7 spinules, propodus with 8–23 spinules, carpus with 3 spines, merus with 7–11 spines, ischium with one spine. Dorsal posterior margin of abdominal somite 3 slightly produced. Pleuron of abdominal somite 4 with strong ventral point, pleuron of somite 5 with strong posterolateral point. Somite 6 shorter than telson. Telson with 4–6 pairs dorsolateral spines. Male total length to 230 mm, female to 253 mm. Color in life. Dull red to fawn or tan, with 3 or 4 lateral white stripes on carapace. Pair of conspicuous white spots on dorsolateral surface of abdominal somites 1, 5. Third maxillipeds, pereopods, antennal flagella banded with red, white. Juveniles camouflaged with brown, green or red color similar to algae, eelgrass (Butler 1980). Habitat and depth. Juveniles usually shallower than adults, among sea grasses or algae, adults usually among rocks or on steep slopes, intertidal zone to 487 m. Range. Unalaska I. to off San Diego; Sea of Japan north along Asiatic Pacific coast. Type locality Unalaska I. Remarks. Observations off British Columbia suggest that the shrimp are primarily nocturnal, and may move into shallower waters during the night (Butler 1980). Records from California usually come from deeper subtidal waters, often at the shelf break (about 185 m)., Published as part of Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, pp. 1-307 in Zootaxa 3371 on page 103, {"references":["Brandt, F. (1851) Krebse. In: Von Middeendorf, A. T. Reise in den aussersten Norden und Osten Sibiriens wahrend der Jahre 1843 und 1844 mit allerhochster Genehmigung auf Verabnstaltung der Kaiserlichen Akademie der Wissenschaften zu St. Petersburg ausgefuhrt und in Verbeindung mit vielen Gelehrten herasugegeben. 2 (Zoologie), 77 - 148.","Holmes, S. J. (1900) Synopsis of California stalk-eyed Crustacea. Occasional Papers of the California Academy of Sciences, 7, 12 - 62.","Rathbun, M. J. (1904) Decapod crustaceans of the northwest coast of North America. Harriman Alaska Expedition, 10, 1 - 219.","Schmitt, W. L. (1921) The marine decapod Crustacea of California. University of California Publications in Zoology, 23, 1 - 470.","Kozloff, E. N. (1974) Keys to the Marine Invertebrates of Puget Sound, the San Juan Archipelago, and Adjacent Regions. University of Washington Press, Seattle, 226 pp.","Word, J. & Charwat, D. (1976) Invertebrates of Southern California Coastal Waters. II. Natantia. Southern California Coastal Water Research Project, El Segundo, California. 238 pp.","Butler, T. H. (1980) Shrimps of the Pacific Coast of Canada. Canadian Bulletin of Fisheries and Aquatic Science, 202, 1 - 280.","Wicksten, M. K. (1980 c) Mainland and insular assemblges of benthic decapod crustaceans of southern California. In: Power, D. M. (Ed). The California Islands: Proceedings of a Multidisciplinary Symposium. Santa Barbara Museum of Natural History, Santa Barbara, California, pp. 357 - 367.","Wicksten, M. K. (1989 b) Ranges of offshore decapod crustaceans in the eastern Pacific Ocean. Transactions of the San Diego Society of Natural History, 21, 291 - 316.","Jensen, G. C. (1995) Pacific Coast Crabs and Shrimps. Sea Challengers, Monterey, California, 87 pp.","Stimpson, W. (1857 b) On the Crustacea and Echinodermata of the Pacific shores of North America. Journal of the Boston Society of Natural History, 6, 444 - 532.","Kingsley, J. S. (1878 b) Notes on the North American Caridea in the Museum of the Peabody Academy of Science at Salem, Mass. Proceedings of the Academy of Natural Sciences of Philadelphia, 30, 89 - 98."]}

Pandalus brevis Rathbun, 1906, based on an Hawaiian specimen and never rediscovered until now, was found in Madagascar and is redescribed. The reexamination of Rathbun's type reveals that this species belongs to the genus Bitias Fransen, 1990, which with Billas stocki Fransen, 1990, includes now 2 species which are compared.

A new species of the pandalid shrimp genus Pandalus Leach, 1814, Pandalus ivanovi n. sp., is described on the basis of material from the Sea of Okhotsk off eastern Sakhalin, at depths of 150–200 m. It is morphologically closest to Pandalus hypsinotus Brandt, 1851, a commercially important species widely distributed in the northern North Pacific. Because of the strong similarities between the new species and P. hypsinotus, we have examined syntypes of the latter species in order to confirm the specific identity. The new species can be distinguished from P. hypsinotus by the more strongly upturned rostrum, the relatively low postrostral ridge on the carapace, fewer carpal articles of the left second pereopod and the small body size. The coloration in life is also different between the two. There is an indication of protandry in the new species, like other congeneric species.

Pandalus ivanovi n. sp. (Figs 1 ���6, 8) Material examined. Holotype: CBM-ZC 9221, female (CL 28.4 mm), off eastern Sakhalin, Sea of Okhotsk, 46 ��N, 145 ��E, 2005, 150 ��� 200 m, rocky bottom, commercial fishing using shrimp basket, S. Miyaki leg. Paratypes: CBM-ZC 9222, 2 females (CL 31.0, 31.4 mm), same data as holotype; CBM-ZC 9223, 20 females (CL 30.2���35.6 mm), same data as holotype; MNHN-Na 16873, same data as holotype; NSMT-Cr 18306, same data as holotype; CBM-ZC 9224, 4 females (CL 30.6���33.1 mm), similar locality, 2005, M. Fujiwara leg.; VNIRO, 19 transitional males (CL 27.6 ���30.0 mm), 5 females (CL 29.0��� 31.5 mm), 3 ovigerous females (CL 27.3���33.9 mm), off eastern Sakhalin, 49 �� 15 ���N 144 �� 35 ���E to 49 �� 15 ���N 144 �� 39 ���E, 90���120 m, FRV Viktoriya 2, September 2001. Description. Females. Body (Fig. 1) moderately robust. Rostrum (Fig. 2 A, B) strongly curving dorsally, overreaching distal margin of antennal scale, 1.02���1.25 times as long as carapace; dorsal margin armed with 16���24 movable spines, including 9���14 on rostrum proper and 6���9 on carapace posterior to orbital margin, and 1 or 2 small fixed teeth near apex of rostrum, subdistal 0.50���0.60 leaving unarmed, posteriormost (first) spine arising at posterior to midlength of carapace (0.55���0.59 of carapace length); ventral margin armed with 7���9 fixed teeth increasing in size posteriorly, posteriormost tooth distinctly stronger than others; lateral carina conspicuous in posterior half. Carapace (Fig. 2 A) with postrostral ridge moderately high, somewhat crested but non-arched, extending nearly to posterodorsal margin; dorsal margin gently convex in lateral view, posteriormost 1���4 spines on peak; antennal tooth moderately strong; branchiostegal tooth small; no conspicuous ridges or carinae on lateral surface. Pleon (Figs 1, 2 C) dorsally smooth. Third somite without middorsal projection or posterodorsal median tooth. Fourth and fifth somites each with posterolateral tooth on pleuron. Sixth somite about 0.40 times as long as carapace and 1.70���1.80 times longer than high; posterolateral process terminating in acute tooth. Telson (Fig. 2 D) moderately broad, armed normally with 5 or 6 pairs of dorsolateral spines; posterior margin terminating in small blunt triangular projection, with 3 pairs of unequal spines. Eye (Fig. 2 A, E) broadly subpyriform, maximal diameter of cornea 0.17���0.20 of carapace length; ocellus present. Antennular peduncle (Fig. 2 A, E) reaching midlength of antennal scale; first segment with short, rounded stylocerite; second segment unarmed on dorsal surface, but with few spinules on dorsodistal margin; distal 2 segments slightly shorter than first segment; aesthetasc-bearing portion of outer flagellum distinctly shorter than carapace. Antennal (Fig. 2 A, E) with stout basicerite bearing moderately strong ventrolateral tooth; carpocerite moderately stout, far falling short of midlength of antennal scale; antennal scale 0.82���0.88 times as long as carapace and 4.20���4.50 times longer than broad, lateral margin nearly straight, distolateral tooth reaching distal margin of rounded lamella. Mouthparts usual of genus (see Komai, 1999). Third maxilliped (Figs 1, 3 A, 4 A) slightly overreaching distal margin of antennal scale; ultimate segment about 1.80 as long as penultimate segment (= carpus), terminating in small corneous spine, with numerous scattered spinules and several tufts of short setae on lateral surface and 2 or 3 tufts of longer spinules on dorsal margin subdistally; mesial face of ultimate segment with numerous transverse tracts of stiff setae and few long spines; carpus also with several spinules on lateral surface and numerous stiff setae on mesial surface; antepenultimate segment (merus-ischium-basis fused segment) slightly shorter than distal 2 segments combined, with small rounded tubercle basally on dorsal surface; dorsal surface elevated at midlength; ventral margin forming blunt edge fringed with row of numerous short setae; exopod absent. First pereopod (Fig. 3 B) minutely chelate, slender, slightly falling short of distal margin of antennal scale; propodus about 0.60 times as long as carpus, tapering distally, with distinct longitudinal groove lined with tufts of short setae; ischium with narrow ventral lamina terminating acutely or subacutely at ventrodistal angle; row of spinules partially obscured by stiff setae present on ventral margin of ischium. Second pereopods greatly unequal with left much longer and slender than right. Left second pereopod (Fig. 3 C) greatly elongate, overreaching antennal scale by 0.80���0.90 length of carpus; chela small, dactylus slightly shorter than palm; carpus elongate, divided in 54���61 articles; merus entirely annulated; ischium distally annulated, ventral margin slightly expanded in proximal half to accommodate chela. Right second pereopod (Fig. 3 D) overreaching antennal scale by 0.3 length of carpus; chela about 0.25 times as long as carpus, dactylus shorter than palm; carpus divided in 19���24 articles; merus with few annulations distally; ischium entire, similar to left in structure. Third to fifth pereopods decreasing in length toward posterior. Third pereopod (Fig. 3 E) overreaching antennal scale by 0.5���0.6 length of propodus, subprehensile; dactylus (Fig. 4 C) sickle-shaped, 0.32��� 0.47 times as long as propodus, with 22���27 accessory spinules becoming longer and more widely spaced distally and 1 subterminal spinule appressed to slender unguis; propodus slightly recurved, laterally compressed, all surfaces with scattered spinules, particularly flexor surface with numerous scattered spinules flanked by rows of long spinules (spinules becoming fewer proximally) (Fig. 4 D); carpus 0.50���0.60 times as long as propodus, with 2 or 3 lateral and 1 ventromesial spines and with scattered spinules on lateral to mesial faces (Fig. 4 E); merus 0.86���0.94 times as long as carapace, armed with 7���9 lateral and 6���9 ventral spines; ischium with 1 ventrolateral spine. Fourth pereopod (Fig. 3 F) overreaching antennal scale by length of dactylus; dactylus (Fig. 4 F) 0.22���0.34 times as long as propodus, armed with 17���21 accessory and 1 subterminal spinules; propodus nearly straight, less spinose than third; carpus with 3 lateral and 1 ventral spines and scattered spinules on lateral to mesial faces; merus 0.72���0.79 times as long as carapace, with 5���8 lateral and 5���8 ventral spines; ischium with 1 ventral spine. Fifth pereopod (Fig. 3 G) falling short of distal margin of antennal scale; dactylus (Fig. 4 G) short, somewhat curved, 0.15���0.22 times as long as propodus, with 9���12 accessory and 1 subterminal spinules; propodus with 2 rows of long spinules on flexor surface and with tufts of grooming setae distally (Fig. 4 G); carpus with scattered spinules on dorsal surface and with 2 lateral and 1 ventral spines; ischium with 1 ventral spine. First pleopod with simple endopod. Second pleopod completely lacking trace of appendix masculina. Uropod (Fig. 2 C) with rami subequal in length, reaching nearly to tip of telson. Eggs numerous; size 0.83 ���1.00 mm along short axis and 1.00��� 1.17 mm along long axis. Transitional males. Generally similar to females (Fig. 5 A). Rostrum 1.08���1.33 times longer than carapace. Endopod of first pleopod (Fig. 5 B, D) with subterminal appendix interna; proximomesial lobe well delineated. Appendix masculina on second pleopod (Fig. 5 C, E) slender, 1.8 ���2.0 times longer than appendix interna, bearing single or few spiniform setae terminally. Coloration in fresh. See Fig. 6 A. Background reddish brown. Rostrum pale, with red band distal to midlength, tip also reddish. Carapace with obscure transverse band along anterolateral margin, otherwise mottled with red or reddish brown. Red or reddish brown blotches on dorsal and lateral surfaces of first to sixth pleonal somites, often forming broad transverse band. Antennal flagellum with alternating red and white. Third maxilliped red, with dark reddish brown band around joint between ultimate and penultimate segments. First pereopod also red, with banding on propodus and carpus. Second pereopod each with carpus fading distally, chela white; merus and ischium red. Third to fifth pereopods generally pink; propodi each with reddish brown band subdistally, and often with second subproximal band; banding also present on meri. Uropod red. Distribution. So far Known only from off eastern Sakhalin, Sea of Okhotsk, at depths of 90��� 200 m. Biology. In the Sea of Okhotsk, shrimp of the genus Pandalus and Pandalopsis form a major fishery resource, and it has been generally considered that the local shrimp fauna is well documented. Thus, the discovery of a new species having a high potential of commercial value from a rather well explored area is surprising. Perhaps, the habitat preference has prevented the discovery of this new species. The captain of the fishing boat capturing the new shrimp reported that the shrimp inhabited hard bottom, and that Pandalus hypsinotus did not occur in the fishing ground where P. ivanovi n. sp. was fished (S. Miyaki, personal communication). The available material suggests that Pandalus ivanovi n. sp. is a protandrous hermaphrodite like other congeneric species (Komai, 1999; Bergstrom, 2000), although no specimens of functional males were available for study. Nineteen specimens (CL 27.6 ���30.0 mm) have subterminal appendices internae on the endopod of the first pleopod and slender, nearly unarmed appendix masculina on the second pleopod. These features suggest that the specimens are in an early stage of transitional phase (Butler, 1980; Komai, 1999). Females are generally larger than those of transitional males, measuring 29.0��� 35.6 mm in CL. Etymology. This new species is dedicated to the late Boris G. Ivanov, in recognition of his contributions to the taxonomy of the decapod Crustacea. He was the supervisor of the second author. Remarks. The new species is referred to the Pandalus hypsinotus group of Komai (1999), including eight species, viz., P. chani Komai, 1999, P. hypsinotus, P. formosanus Komai, 1999, P. gracilis Stimpson, 1860, P. gurneyi Stimpson, 1871, P. nipponensis Yokoya, 1933, P. p re n s o r Stimpson, 1869, and P. teraoi Kubo, 1937. It is very similar to P. hypsinotus in the morphology and the general coloration in life. Shared characters are: the number of spines of the dorsal rostral series could be within a range of 18���24, of which seven to nine spines are on the carapace; the posteriormost spine of the dorsal rostral series arises distinctly posterior to the midlength of the carapace; the postrostral ridge is markedly elevated, thus the dorsal margin of the carapace is convex; the pleon is banded with dark reddish brown. Counts of spines or spinules on segments of the pereopods also agree for each other. Because of the strong similarity between the two taxa, we have examined the syntypes of Pandalus hypsinotus (type locality: Unalaska; Brandt, 1851) in order to confirm the specific identity. The condition of the syntypes is poor, but characters necessary for species recognition are still preserved (Fig. 7). It was confirmed that the eastern Sakhalin shrimp is an undescribed species. The new species differs from P. hypsinotus in variable but apparently significant morphological characters. The rostrum is more strongly curved (cf. Figs. 2 A and 6 B), and tends to be proportionally shorter in P. ivanovi than in P. hypsinotus although the values partly overlap (Fig. 8). The proportional value against the carapace length ranges 1.02���1.29 (1.12 on average, n= 55) in P. ivanovi, and 1.19���1.58 (1.332 on average, n= 43) in P. hypsinotus. The postrostral ridge in transitional males and females is distinctly lower in P. ivanovi than in P. hypsinotus. The development of the postrostral ridge shows an ontogenetic variation in P. hypsinotus (cf. Komai, 1999), and thus perhaps it will be not reliable in identifying functional males. The carpal articles of the left second pereopods are constantly fewer in Pandalus ivanovi than in P. hypsinotus (54���63 versus 72���85). The dactylus of the fifth pereopod seems to be more strongly curved in P. ivanovi than in P. hypsinotus. The coloration in life is also different between the two species (cf. Fig. 7 A, B). The general body color is more reddish in the new species than in P. hypsinotus; bands on the pleon are wider in P. ivanovi n. sp. than in P. hypsinotus. Furthermore, Pandalus ivanovi n. sp. is characterized by its relatively small size; the largest specimen of P. ivanovi is 35.6 mm in CL; female specimens, including ovigerous, are 27.3���35.6 mm. The maximum size appears considerably different in P. hypsinotus according to different populations. Female specimens from East Asia are 36.1 ���45.0 mm in CL, and the specimens of less than 36 mm in CL are all functional males or transitional individuals. On the other hand, the female specimens from Canada are 32.5 ���40.0 mm in CL. It is interesting to note that the two separate populations of Pandalus hypsinotus show differences in the relative length of the rostrum and overall body size. The rostrum seems to be proportionally longer in the Asian population than in the Canadian population (1.29���1.57 times as long as the carapace versus 1.19���1.42), although the values partially overlap. The body size is larger in the Asian population than in the Canadian population (transitional males CL 36.6���42.3 mm, females CL 36.1���47.5 mm versus transitional males CL 31.0���33.0 mm, females CL 33.6 ���40.0 mm). Haynes (1976), who described the larval stages of Pandalus hypsinotus from Alaska, noted several morphological differences between his larvae and those described by Kurata (1964) from Hokkaido, Japan. Detailed comparison will be necessary if the geographically separated populations belong to a same species. It remains unclear whether the new species is endemic to the Sea of Okhotsk. Nevertheless, in spite of our collecting efforts, no specimens of the new species have been encountered in the collections made during recent fishery or scientific surveys or those in museum collections., Published as part of Komai, Tomoyuki & Eletskaya, Maria, 2008, A new species of the pandalid shrimp genus Pandalus (Crustacea: Decapoda: Caridea) from the Sea of Okhotsk off eastern Sakhalin, Russian Far East, pp. 46-56 in Zootaxa 1882 on pages 47-55, DOI: 10.5281/zenodo.184238, {"references":["Komai, T. (1999) A revision of the genus Pandalus (Crustacea: Decapoda: Caridea: Pandalidae). Journal of Natural History, 33, 1265 - 1372.","Bergstrom, B. I. (2000) The biology of Pandalus. In: Southward, A. J., Tyler, P. A., Young, C. M. & Fuiman, L. (Eds.), Advances in Marine Biology. Vol. 38. Academic Press, London, pp. 57 - 228.","Butler, T. H. (1980) Shrimps of the Pacific coast of Canada. Canadian Bulletin of Fisheries and Aquatic Science, 202, 1 - 280, pls 1 - 6.","Brandt, F. (1851) Krebse. In: Middendorff, A. Th. v. (Ed.) Reise in den aussersten Norden und Osten Sibiriens wahrend der Jahre 1843 und 1844 mit allerhochster Genehmigung auf veranstaltung der Kaiserlichen Akademie der Wissenchaften zu St. Petersburg ausgefuhrt und in Verbindung mit vielen Gelehten herausgegeben, 2 (1), 79 - 148, pls. 5, 6.","Haynes, E. (1976) Descriptions of zoeae of coonstripe shrimp, Pandalus hypsinotus, reared in the laboratory. Fishery Bulletin, 74 (2), 323 - 342.","Kurata, H. (1964) Larvae of decapod Crustacea of Hokkaido. 3. Pandalidae. Bulletin of the Hokkaido Regional Fisheries Research Laboratory, 28, 23 - 34."]}

The olfactory organ in decapod crustaceans is represented by the outer antennular flagellum with specialized sensilla called aesthetascs. Characteristic structures of the lateral antennular flagellum with olfactory setae in larvae, juveniles and adults of grass shrimp Pandalus kessleri Czerniavski, 1878 are described. Орган обоняния десятиногих ракообразных представлен наружными жгутами антеннул, с расположенными на них специализированными чувствительными щетинками — эстетасками. Описаны особенности строения латерального жгута антеннулы с обонятельными щетинками у личинок, молоди и половозрелых особей травяной креветки — Pandalus kessleri Czerniavski, 1878.

The changes in GSI and HSI of Pandalus kessleri were monitored during an annual reproductive cycle. GSI reached a peak when ovaries were composed of yolky oocytes and decreased sharply during the spawning season. HSI followed a similar pattern. The changes in the concentrations of progesterone- and estradiol-17β-like substances in the hemolypmh were also investigated. Progesterone levels increased at the onset of vitellogenesis and decreased during vitellogenesis. In contrast, estradiol concentrations rose during the peak of vitellogenesis and dropped after the release of mature eggs from the gonad.

Pandalus gracilis Stimpson, which has been synonymized with P. hypsinotus Brandt, is revived as a good species. Both species occur in the Japanese fauna. It is more closely related to P. prensor Stimpson than to P. hypsinotus. The three species show a number of morphological differences; furthermore P. prensor is the smallest of the three, and P. hypsinotus the largest. The life span of P. hypsinotus is longer than that of P. gracilis. P. gracilis is known to occur rathe abundantly in the southern part of the Sea of Japan, but the commercial value is not high, because of the small size.

[Eine vollstandige Beschreibung der Larvenstadien von Pandalus jordani Rathbun wird anhand der im Labor gezuchteten Exemplare als auch von weit von der Oregonkuste (in den Vereinigten Staaten von Nordamerika) eingesammelten Planktonsammlungen, gegeben. Diese Beschreibung wird mit einem vorangehenden, unvollstandigen Bericht verglichen. Einflusse des niedrigen Grades der Entwicklung auf die Ausschlupfung und auf die grosse Zahl der Larvenstadien von P. jordani werden diskutiert und mit anderen Arten der Gattung verglichen. Eine mogliche Beziehung zwischen Variationen in der Geschichte des Larvenlebens und der geographischen Verteilung der Gattung wird untersucht., Eine vollstandige Beschreibung der Larvenstadien von Pandalus jordani Rathbun wird anhand der im Labor gezuchteten Exemplare als auch von weit von der Oregonkuste (in den Vereinigten Staaten von Nordamerika) eingesammelten Planktonsammlungen, gegeben. Diese Beschreibung wird mit einem vorangehenden, unvollstandigen Bericht verglichen. Einflusse des niedrigen Grades der Entwicklung auf die Ausschlupfung und auf die grosse Zahl der Larvenstadien von P. jordani werden diskutiert und mit anderen Arten der Gattung verglichen. Eine mogliche Beziehung zwischen Variationen in der Geschichte des Larvenlebens und der geographischen Verteilung der Gattung wird untersucht.]

Les stades larvaires 1-6 de la crevette ouest-pacifique Pandalus prensor ont ete eleves en laboratoire, et figures et decrits en detail. Les larves eclosent a l'etat avance, avec des pereiopodes bien developpes et des rudiments de pleopodes. Le developpement postembryonnaire apparait ainsi comme abrege. L'heterochronie du developpement des appendices chez les larves est discutee.

Der Lectotypus von Pandalus gracilis Stimpson, 1860, aus Hakodate (Japan), der sich in der Sammlung des British Museum (Natural History) befindet, wurde untersucht. Es erwies sich als spezifisch identisch mit Pandalus hypsinotus Brandt, 1851. Der letztgenannte Name muss demnach fur die Art benutzt werden. Pandalus prensor Stimpson, 1860, auch von Hakodate, ist, der Beschreibung nach, identisch mit Pandalus meridionalis Balss, 1914, eine Art die ursprunglich von Balss (1914) als Unterart von P. hypsinotus beschrieben wurde. Der Stimpsonsche Name Pandalus prensor hat Prioritat und soll fur die Art verwendet werden.

Little is known of the larvac of the Pandalidac as is shown by Gurney (1939) in his Bibliography of the Larvae of Decapod Crustacea. Berkeley (1930,1938) describes the life histories of several species of Pandalus and of Pandalopsis dtspar from British Columbia, and Gurney (1937) the larvae and post-larvae of Chlorotocella, but beyond these the information is fragmentary. Sars’ (1900) work on Pandalus borealis and P. bonnieri was formerly regarded as typical of pandalid larvae but these were proved to be Caridion (Lebour, 1930). Sars (1900), however, described in part in an excellent manner the larvae of Pandalus montagui and Pandalina brevirostris and Stephensen (1935) the early larvae of Pandalus propinquus.

[Description des stades zoe de Pandalina brevirostris (Rathke), Dichelopandalus bonnieri (Caullery), Pandalus propinquus G. O. Sars et Pandalus montagui Leach d'apres des eclosions en laboratoire et des echantillons provenant de peches planctoniques. Les larves de P. propinquus n'avaient pas ete correctement identifies jusqu'a present. Un resume des connaissances publiees sur les larves de Pandalidae est donne, et l'evolution des larves et des adultes a l'interieur de la famille est discutee., Description des stades zoe de Pandalina brevirostris (Rathke), Dichelopandalus bonnieri (Caullery), Pandalus propinquus G. O. Sars et Pandalus montagui Leach d'apres des eclosions en laboratoire et des echantillons provenant de peches planctoniques. Les larves de P. propinquus n'avaient pas ete correctement identifies jusqu'a present. Un resume des connaissances publiees sur les larves de Pandalidae est donne, et l'evolution des larves et des adultes a l'interieur de la famille est discutee.]

Synthetic Pandalus red pigment-concentrating hormone was effective in concentrating the pigment in the erythrophores of the fiddler crab Uca pugilator and the dwarf crayfish Cambarellus shufeldti. However, this hormone had no effect on the melanophores of the crab or the leucophores of the crab and crayfish. These results are in accord with the hypothesis that in the fiddler crab and the dwarf crayfish, respectively, the hormonal control for each type of chromatophore is different.

Synthetic Pandalus red pigment-concentrating hormone and extracts of eyestalks from Uca pugilator and Palaemonetes vulgaris were passed through a column of Bio-Gel P-6. In each instance the elution volume of the fraction that provided maximal concentration of the red chromatophoric pigment of Palaemonetes was the same, indicating thereby that these three red pigment-concentrating hormones have either the same or nearly the same molecular size.

The structure of a light-adapting hormone of the shrimp, Pandalus borealis, has been determined. The hormone, which had been isolated from Pandalus eyestalks and which adapts the shrimp to brighter light conditions by causing the pigment in the distal retinal pigment cells of the eye to move into a more proximal position, is the peptide: Asn-Ser-Gly-Met-Ile-Asn-Ser-Ile-Leu-Gly-Ile-Pro-Arg-Val-Met-Thr-Glu-Ala-NH2. The structure was obtained by sequence analysis by the dansyl-Edman method of the intact hormone and of isolated tryptic and thermolytic peptides.

PROTANDROUS hermaphroditism, or the changing from the male sex to the female during the growth of the same individual, is now well known in certain northern-hemisphere commercial prawns of the family Pandalidae, namely, species of the genera Pandalus (P. borealis1, P. danae1, P. hypsinotus1, P. kessleri2, P. montagui3 and P. platyceros1) and Pandalopsis (P. dispar1). In the Hippolytidae, this phenomenon has been demonstrated in two European and Mediterranean species of Lysmata, namely, L. seticaudata (the first decapod in which protandry was recognized4) and L. nilita5.