CRUSTACEAN RESEARCH， N O. 30: 1-20， 2001

Larval stages of the Botan shrimp P a n dαlus nipponensis Y o k o y a， 1933 (Decapoda: Caridea: Pandalidae) under laboratory conditions， with notes o n its lecithotrophic development

H a j i m e Taishaku， H i d e o T a k e o k a a n d Kooichi Konishi

Abstract.- T h e complete larval devel-opment of the Botan shrimp， Pαnd.αlus nipponensis Yokoya， 1933， is deScribed and illustrated based o n laboratory-reared material. Four larval stages (stage 1-4) and two postlarval stages (stages 5， 6) were recognized. The larvae started to feed on Artemiαnauplii from stage 2. Starved larvae survived until stage 3. Ac-cording to Gore's (1985) classification of the developmental types of decapods， the development of P. nipponensis is of an ad-vanced and lecithotrophic type.

Introduction Nine species of the genus Pαndalus

are known from Japan (Miyake， 1998; Komai， 1999)， including five commer-cially important species: P. eous Makarov， 1935， P . hypsinotus Brandt， 1851， P . 1αtirostris Rathbun， 1902 (= P . kessleri Brashnikov， 1907)， P . prensor Stimpson， 1860， and P . nipponensis Yokoya， 1933. These shrimps are distributed in a wide range of depths， from intertidal to deep-sea bottom. Larval development has been documented in detail in four species (Ber-keley， 1930; Kurata， 1955; Kurata， 1964; H a戸時s，1976; Mikulich & Ivanov， 1983)， but only a preliminary report has been published on the Botan shrimp P. nipponensis (Yamamoto et al， 1982). Pαndalus nipponensis is distributed

on the deep continental shelf and slope of the Pacific coast of Japan from Kashima-nada to Kagoshima B a y at 100-480 m ( K o m a i， 1999) . T h e catch of P.

nipponensis has declined greatly in recent years (Yamamoto et al， 1982) and， there-fore， information on its early life history is required for the analyses ofnatural popu-lations and m 出国gement of the species. The present paper describes the com-

plete larval stages of P . nipponensis reared under laboratory conditions and discusses the developmental patterns of Pαn dαlus species.

Material and Methods Ovigerous shrimps were collected仕o m

Enshu-nada at a depth of 300 m using trawling gear in January 1996. A m o n g them， two females， 36 m m in carapace length， carried 585 and 707 eggs， respec-tively. They were kept in an aquarium at about 10 oC. The eggs were elliptical; those of the first female measured 3.71 :t 0.15 x 2.41 :t 0.11 m m (10 specimens) and those ofthe second female 3.13 :t 0.12 x 2.26 :t 0.09 m m. Newly hatched larvae were reared in two polycarbonate tanks each containing five liters of sea water and 10 larvae. They were fed with Artemiαnauplii and the seawater changed daily. Non-fed larvae were also cultured as a control. They were kept in-dividually in 200 ml vessels， and exuviae were removed immediately after each molt to prevent consumption. The larvae and exuviae of each stage

were fixed by 5% buffered formalin for morphological observation. Dissection and measurement were conducted using an Olympus S Z H stereomicroscope with

2 H. T A I S H A K U E T A L.

fine insect pins. Drawings were m a d e with the aid of a drawing tube attached to an Olympus BH-2 microscope. The cara-pace length (CL) was measured from the tip of rostral spine to the medial posterior margin ofthe carapace. Most ofthe termi-nology for setae follows that of Ingle (1992). All setal arrangements are listed from proximal to distal. The specimens used in this study are

deposited in the Zoological Institute， Fac-ulty of Science， Hokkaido University un-der registration numbers ZIHU1365・1370 (larvae) and Z I H U 1371 (ovigerous female).

Results Four larval stages were recognized in

P. nipponensis. Newly hatched larvae of P . nipponensis corresponded to the zoea 1 stage following the definition of zoeallar-vae (Gurney， 1942; Williamson， 1969)， but it has some advanced morphological characters that are normally found in later larval stages in most caridean shrimps，白，r example the antennule， max-illa，m a垣lliped 3， pereopods 1-2， pleopods and uropods (Table 1). It is， therefore， hardly acceptable to call these stages as “zoea" in the s出 ct sense. W e use the term “stages 1-4"血stead of“zoeae 1-4" in this paper. It took about 40 days from hatch-

ing to stage 5 (=postlarva 1) at 10 oC. Fig. 1 A shows the C L of each stage of

larvae fed with Artemia nauplii. The m e a n increment rate of the C L between successive stages is lower after stage 4: those of stages 1-2， 2-3， 3-4 were 132， 134， 1429もand those of stages 4-5， 5-6 were 109， 122%， respectively. The larvae started to feed (Artemiαnauplii) from stage 2. The larvae of the starved series survived until stage 3 and then died (Figs. 1 B， B'). Swimming behavior using the exopods of pereopods 1-2 was observed only in stage 1， when they reacted to light and vibrations.

Description Pαn dαlus nipponensis Yokoya， 1933

Figs.2-11 Stage 1

Dimension: C L = 2.85::tO.07 m m (range 2.70-2.93 m m， 10 specimens). Carapace (Fig. 2 A， A'): Rostrum short，

spiniform， directed downward， without teeth. Posterolateral margin rounded. Anterolateral margin with antennal spine. Eyes sessile. Antennule (Fig. 3A): Uniramous，

protopod with a distal plumose seta. Exopod unsegmented process with 3 aesthetascs.

Table 1. Developmental phase of appendages in the larval stages of Pandαlus niponensis Yokoya. Appendage Stage

1 2 3 4 5 6 A ntennule L PL PL PL PL PL A ntenna PL PL PL PL PL PL Mandible L PL PL PL P L PL Maxillule PL PL PL PL PL P L Maxilla U P L PL PL PL PL P L Maxillipeds 1， 2 PL PL P L PL PL PL Maxilliped 3 & pereopods 1， 2 L PL PL PL PL P L Pereopods 3-5 PL PL P L PL PL PL Pleopods L L L L PL P L Telson & uropod L L U P L PL PL PL Arthrobranchs L L L L PL PL L: larval， PL: postlarval.

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 3

A ntenna (Fig. 3E): Biramous， well-de-veloped. Coxa and basis separated and a spine at distolateral corner of basis. Endopod (= flagellum) well developed， much longer than CL. Exopod (=田ltennalscale or scaphocerite) flattened， with a distolateral spine and 46-47 plumose se-tae on mesial and distal margins. Mandible (Fig. 4A): Incisor and molar

processes indistinctly separated， armed with several teeth on mesial margin. Palp well developed， but unsegment. Maxillule (Fig. 4D): Coxal endite slen-

der， with 1 plumose and 9 simple setae. Basial endite broad， with 2 rows of 14 simple spines and 15 simple setae on me-sial margin. Endopod with 3 minute se-tae. Maxilla (Fig. 5A): Bilobed coxal and

basial endite with 11+2 and 5+9 setae re-spectively. Endopod unsegmented， with 8 setae. Exopod (= scaphognathite) plate-like， with 53-58 plumose setae. Maxilliped 1 (Fig. 5D): Protopod bi・

lobed， proximal lobe with 6 setae， distal lobe w i t h 18 setae . E n d o p o d unsegmented， with 7 setae. Exopod with long slender ramus enlarged at base (= caridean lobe)， with 6 terminal natatory setae and 11 plumose lateral setae. Epipod bilobed. Maxilliped 2 (Fig. 6A): Similar to adult

form but less setose. Endopod 5-seg-mented; propodus obliquely articulated to carpus， distal 3 segments with 3， 1， 1， se-tae respectively， dactylus and propodus with several minute setae. Exopod longer than endopod， with 9 natatory plumose setae terminally. Epipod bilobed. Maxilliped 3 (Fig. 6D): Endopod 4-seg-

mented. Exopod longer than endopod， with 10 natatory plumose setae distally. Pereopods (Figs 6J， 7 A， 8 A， 8 D， 8G):

Pereopod 1 biramous， endopod 3・seg-mented， minutely chelate and exopod unsegmented with 10 natatory plumose setae. Pereopod 2 biramous， chelate， left longer than right; endopod 5-segmented; exopod as in pereopod 1. Pereopods 3-5

uniramous， segmented as in adult form. Abdomen (Fig. 2A): Six somites plus

spatulate telson. Dorsal surface of each somite smooth， without armature. Pleopods (Fig. 2A): Rudimentary small

buds on abdominal somites 1-5. Telson and uropods (Fig. 10A): Telson

distally rounded in dorsal aspect， slightly notched posteromedially; posterior mar-gin fringed with 23-25 plumose setae. Rudiments of uropods visible under cu-ticle on ventral side. Gills (Fig. 11A): Arthrobranch absent.

Pleurobranch present on thoracic somites 4-8， well developed. Epipod present on pereopods 1-4.

Stage 2 Dimension: C L = 3.75 :t 0.14 m m

(range 3.45-3.95 m m， 9 specimens). Carapace (Fig. 2B): Rostrum styliform，

distinctly overreaching anterior margin of eye， about 0.8 times as long as cara-pace; dorsal margin armed with 13-14 minute teeth including 3-5 behind level of posterior margin of orbit， posteriormost one situated on about anterior 0.15 of carapace， none with basal suture; ventral margin armed with 3-5 minute teeth. An-tennal and pterygostomian spines on an-terior margin. Antennule (Fig. 3B): Peduncle 3・seg-

mented; proximal segment bearing， small stylocerite with acute tip， concave on outer margin and with about 20 setae on distolateral corner; penultimate segment with 12 setae; distal segment with 6 se-tae. Inner flagellum (= endopod) 2・seg-mented with 2， 3 setae respectively; outer flagellum (= exopod) not developed. In some specimens， inner flagellum 3-seg-mented with 0， 2， 1+3 setae respectively; outer flagellum divided into 4 articles， with 2-4 aesthetascs on each article. A ntenna (Fig. 3F): N o major change. Mandible (Fig. 4B): Incisor and molar

processes well separated by deep cleft. Palp 3・segmented，with 0， 0-2， 7 setae. Maxillule (Fig. 4E): Coxal endite with

4 H . T A I S H A K U E T AL.

17 plumose setae. Basial endite with double row of 14 simple spines and 21 plu-mose setae on mesial margin. Endopod with 2 plumose setae. Maxilla (Fig. 5B): Coxal endite with

only a few setae. Bilobed basial endite with plumose setae， 15 on proximallobe， 25 on distal lobe respectively. Endopod unsegmented， with 3 plumose setae. Maxilliped 1 (Fig. 5E): Protopod with 2

lobes: proximallobe with 11 setae， distal lobe with 47-61 setae. Endopod 2・seg-mented， with 2， 3 setae respectively. Maxilliped 2 (Fig. 6B): Dactylus and

propodus with about 50 and 20 setae re-spectively. Maxilliped 3 (Fig. 6E): Endopod 3-seg-

mented. Exopod rudimentary. Pereopods (Figs 6 K， 7 B， 8 B， E， H):

Pereopod 1 and 2 each with rudimentary exopod. Meri ofpereopods 3， 4 armed with a subdistal spine and a lateral spine; car-pus with a subdistal spine in pereopods 3， 4. Abdomen (Fig. 2B'): All somites with

setae on ventral m 訂 gins of pleura. Pleopods (Fig. 2 B'): Larger than in

stage 1， but non-functional. Telson and uropods (Fig. 10B): Telson

合inged with 22 plumose setae. Visible en-closed uropods enlarged. Gills (Fig. 11B): Arthrobranch bud on

thoracic somites

Stage 3 Dimension: C L = 5.04:!::0.10 m m (r組 ge

4.9-5.20 m m， 11 specimens). Carapace (Fig. 2C): R ostrum almost as

long as carapace; dorsal margin armed with 16-19 teeth including ←6 behind level of posterior margin of orbit， anteriormost one situated near apex of rostrum， remotely separated from re-mainder， posteriormost one situated on 田 lterior quarter of carapace; ventral mar-gin armed with 5-6 teeth. A ntennule (Fig. 3C): T wo types recog-

nized: Rudimentary outer flagellum with

6 aesthetascs; elongated， 4・segmentedouter flagellum， each segment with 3-5 aesthetascs. Mandible (Fig. 4C): Palp 3・segmented

with 0，1-4，10 setae. Maxilliped 3 (Fig. 6F): N o remarkable

change. Pereopods (Figs 6L， 7 C， 8 C， F， I): Meri

of pereopod 3 armed with a ventral spine， and a subdistal spine in pereopod 5. Pleopods (Figs 9A-E): Biramous but

still not functional. Telson and uropods CFig. 10C): Uro-

pods differentiated. Telson widened pos・teriorly， armed with 1 spine on each side and 9 pairs ofterminal setae. Gills (Fig. 11C): Epipods on pereopods

1， 2 bearing distal hook. Stage 4

Dimension: C L = 7. 12::!::0.09 m m (range 7.00-7.30 m m， 9 specimens). Carapace CFig. 2D): Rostrum slightly

curving dorsally， about 1.1 times as long as carapace; dorsal margin armed with 17-19 teeth including 5 behind level of posterior margin of orbit， posteriormost one situated on anterior over 0.25 of cara-pace， posterior 2 or 3 teeth with basal su-ture; ventral margin armed with 7-8 teeth. Maxilliped 3 (Fig. 6G): N o major

change. Pereopods: N o remarkable change. Pleopods (Figs. 9 F-，J): Each ramus in-

completely separated企o m protopod， hav-ing natatory setae on distal margin of exopod only in pleopod 2. Appendix intemae on endopods of pleopods 2- 4 ru-dimentary. Telson and uropods (Fig. 10D): Poste-

rior margin of telson n但 Tower than ante-rior end， bearing 5 pairs of stout spines， and 3 pairs of spines on dorsal side. N o remarkable change in uropods. Gills CFig. 11D): T w o buds of

arthrobranchs on thoracic somite 3. Epipod on pereopod 3 bearing distal hook.

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 5

Stage 5 (Postlarva 1， decapodid) Dimension: C L = 7.8l:t0.46 m m (range

7.13-8.37 m m， 9 specimens). Carapace (Fig. 2E): Rostrum curved

dorsally， about 1.25 times as long as cara-pace， dorsal margin armed with 17-19 teeth including 5-6 behind level of poste-rior margin of orbit， posteriormost one situated at point third from posterior margin of orbit， all teeth with basal su-ture except anteriormost one， ventral margin armed with 8-9 teeth. Maxilliped 3(Fig. 6H): N o major

change. Pereopods: N o major change. Pleopods (Figs 9K-O): Each ramus

completely separated from its protopod except for endopod of pleopod 1， having natatory setae on distal margin. Appen-dix internae on endopods of pleopods 2-5， each with adhesive hooks. Telson (Fig. 10E): Posterior border

with 4 pairs of stout spines. G i1ls (Fig. llE): Arthrobranchs on tho-

racic somites with 3-6 lamellate. Stage 6 (Postlarva 2)

Dimension: C L = 9.5l:t0.26 m m (range 9.00-9.88 m m， 10 specimens). Carapace (Fig. 2F): Rostrum with dor-

sal margin armed 17-20 teeth including 6-7 behind level of posterior margin of or-bit， posteriormost on anterior over 0.3 of carapace， ventral margin armed with 8-10 teeth. Maxilliped 3 (Fig. 61): N o major

change. Pereopods: N o major change. Pleopods (Fig. 9P): Pleopod 1 c o m・

pletely separated from protopod. Telson (Fig. 10F): Posterior margin

narrower than in stage 5. Gills (Fig. llF): Arthrobranch on tho-

racic somite 7 lamellate. Epipod on pereo-pod 4 bearing distal hook.

Discussion A mong 19 species known in the genus

Pαndαlus， the complete larval develop-

ment is reported for 10 species (Table 2). There is a wide variation in the number of larval stages， from two to thirteen， within the genus. Pαn dαlus nipponensis nor-mally molts to the postlarva 1 after four larval stages (Table 1). Such an abbrevi-ated larval development is also found in P. latirostris (two stages)， P. prensor (three stages) and P . plαtyceros (four stages). Gore (1985) defined two types of abbreviated development: direct develop-ment and advanced development. The lar-val development of P. nipponensis belongs to the advanced type of Gore's classifica-tion. T he characters of advanced develop-ment in the larvae of P. nipponensis are recognized in the appendages of stage 1 (Table 1). These are: 1) well developed an-tennal exopod， 2) presence of mandibular palp， 3) rounded basial endite of maxillule， and 4) unequal pereopod 2. These advanced characters are only ob-served in the postlarval stages of Pandalus species with long term develop-ment， as in P. jordαni (see Rothlisberg， 1980). Besides these， pereopods 3-5 of stage 1 were also well developed and func-tional， and these appendages lack an exopod. Bottom-dwelling behavior was also observed from stage 1 in P . mpponensls. The larvae of P. nipponensis are easily

distinguished from those of other conge-ners by their larger body size and the presence of a mandibular palp in stage 1 (Table 2). O n the other hand， the larvae of P. nipponensis have two diagnostic fea-tures that are in common with p ，αndαlus according to Lebour (1940): 1) all walking legs (pereopods 3-5) present at hatching， either rudimentary or functional， and 2) exopods on walking legs 1-2 or 1-3. Komai (1999) noted that one ofthe adult features of Pαndαlus species is unequal pereopods 2， the left being longer and more slender and bearing more numerous carpal articles， than the right one. In P. nipponensis， the as戸nmetry in pereopods 2 is observed at stage 1. Diagnostic char-

CI>

Depth of Distribution* References

habitat*(m)

C:haracter of Stage1

Earliest stage of

Rostrum

Pereopod_s _

Mandiblar Somite 6 Uropod

spination 1 2 3 4 5 Pleopod

palp separation

Table 2. Comparison ofthe larval characters of p，αndalus species.

Larval CL I

stage(s) (mm)

Egg size

(mm)

8 ，13)

5) 1) 7) 3，6)

NP

NNP

NA

NNP

NA

NNP

36-457

16-1380

30-1150

5-450

5-790

5-1984

3 3 3 3 m

2 3 2 2 m

M 7 7 6 m

a a a a a

u u u u u

u u u u u

L U L 口 L U L U L u

b b b b b

h u h u h u ・ b ' D

凸 U n u n u n u n u

1.35-1.72

1.29

1.96

1.21

1.16

日 7 6 5 m

1.4 x 0.8

ND

1.2 x 0.9

ND

ND

国 ・ 寸 〉 H m 山 田 〉 同 己 同 司 〉 』 V '

2) 1，5，10)

1) 14)

this study

NEP

NWP

5-501

NNP

0-185

NEP

subtidal-247 NWP

100-480

NWP

30-311

NWP

1 6-117

EP

140-310

NWP

300-500

NWP

500

NWP

P. montα:gui group*

P.jordαni

P. eos

P. borealis

P. goniurus

P. montαgui

P. tridens

P. stenolepis group*

P. stenolepis

P. curuatus

P. hypsinotus group*

P. hypsinotus

P.dαnαe

P. prensor

P. nipponensis

P. gracilis

P.gurn買yi

P. teraoi

P. chαni

P. formosanus

P. platyceros group*

P. platyceros

P. latirostris

49-229

501

3

3 m 3 3

3

2 m 1 1

7? 4 D I -- N : 1

a

a a u u

b b b u u

fe fe f f f

fe fe f f f

fe fe f f f

fe fe f f f

。 A U n u n u n u

問.1.2

1.72

1.76

1.61

2.95

6

a u k u q d 必 官

1.85-1.93 x 2.37-2.74*

ー

ND

1.3 x 1.1

ND

ND

3.1 x 2.3

1，9)

4)

NEP

NWP

0-487

0-9

3

3

a: absent， b: biramus bud， f: functional， fe: functional with exopod， s: setοse， u: uniramus bud，CL: carapace length， EP: eastern Pacific， NA: northern Atlantic， ND: no

data， NP: northern Pacific， NEP: northeastern Pacific， NNP: northern North Pacific， NWP: northwestern Pacific.

事:Komai (1999)， I: from anterior edge of eye to medial posterior margin of carapace.

1) Berkeley (1930)， 2) Needller (1938)， 3) Lebour (1940)， 4) Kurata (1955)， 5) Kurata (1964)， 6) Pike & WiIliamson (1964)， 7) Makarov (1966)， 8) Modin & Cox(1967)， 9)

Price & Chew(1972)， 10) Haynes (1976)， 11) Haynes (1978)， 12) Haynes (1979)， 13) Rothlisberg (1980)， 14) Mikulich & Ivanov (1983)

1 1

5

3

b s

fe fe fe f f

fe fe f f f

12-13

0

1.27

2.97

4 2

ND

2.6 x 2.0

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 7

acters of the pandalid larvae were also re-viewed by Kurata (1964) and Konishi (1997). T he characters were also observed in P. nipponensis: rostrum present from stage 1 and dentate in later stages， and antennular peduncle concave on the outer margins. Komai (1999) revised the genus Pαndαlus and divided the species of this genus into five groups based on adult morphology. p，αndαlus nipponensis is in-cluded in the P. hypsinotus group accord-ing to his classification. Four species of this group， which includes P . nipponensis， share common characters of pereopods in stage 1 (Table 2). In the other five species of the P. hypsinotus group， the larval characters have not been reported. At present， however， the presence of the c o m m o n characters in the pereopods of stage 1 of the above four species m a y sup-port the suitability ofKomai's (1999) divi-sion ofthe genus into five groups. It h a s b e e n suggested that

Pαn dαlopsis is a subordinated clade w i t h i n t h e g e n u s P αn dαlus (Christoffersen， 1989; Komai， 1994). Komai (1999) suggested a sister group re-lationship between p，αndαlopsis and the Pαndalusplαtyceros group. T he advanced development was observed in two of the species in the Pandαlusplαtyceros group: P.plαtyceros (see Berkeley， 1930; Price & C h e w， 1967) and P. latirostris (see Kurata， 1955) and also in three species of Pαn dαlopsis: P. dispαr (see Berkeley， 1930)， P . coccinαtα(Kurata， 1964)， and P. jα:ponicα(see Komai & Mizushima， 1993). However， it is difficult to decide the phylo-genetic status of advanced development in the species of Pαn dαlopsis and the Pαndαlusplαtyceros group because of the limited information. Rabalais & Gore (1985) noted that

larger eggs， long incubation period， and advanced morphology is related to the lecithotrophic nature of the larvae. These larvae hatch from large， yolky eggs upon which they depend for nutritional re-serves， versus planktotrophic larvae

which hatch from small eggs without the energy reserve of yolk and which depend on planktonic prey for energy. T he larvae of P. nipponensis show lecithotrophic de-velopment. The incubation period of eggs of P . nipponensis was not clear. The num-ber of eggs in the present ovigerous fe-males (C.L.= 36.4 and 36.9mm) is 1/3 to 1/ 5 that of P. jordαni (CL = 18-25 m m ) (Modin & Cox， 1967). The m e a n egg size of P. nipponensis was 3.4 x 2.3 m m and this is the largest among those reported forP，αndalus species (Table 2). Pandαlus nipponensis larvae began to feed from stage 2 and molt to stage 6 in the present rearing (Fig. 1). The mandibles and the maxillules play an important role in feed-ing (e.g.， Crain， 1999). In the stage 1 of P. nipponensis， these mouthparts were less developed than those of stage 2. Namely， the mandible was not separated clearly into incisor and molar processes and the teeth on the mandible and the setae on the basial endite of the maxillule were less numerous than in stage 2. A nother example of lecithotrophic development a m o n g Pαn dαlus species is in P . 1αtirostris. This species has large eggs and only two larval stages (Table. 2). The habitat of P. nipponensis some-

times overlaps with that of the anomuran lithodid crab p ，αrαlomis hystrix (De Haan， 1846) and the brachyuran spider crab Goniopugettiαsαgαmiensis (Gordon， 1931). All three species live on the conti-nental shelfbreak (200-300 m deep)， and s h o w lecithotrophic development (Konishi & Taishaku， 1994; Taishaku & Konishi， 2000). It is possible that the lecithotrophic development of these spe-cies is related to their habitat. The deep continental shelf lies between productive， nutrient-enriched shelf seas ('neritic' wa-ters) and nutrient-poor abyssal seas (Barnes & Hughes， 1988). The habitat， therefore， m a y be related to the lecithotrophic larval development of P. nipponensis. O n the other hand， the shal-low-water pandalid Pαndαlus latirostris

8 H. T A I S H A K U E T A L

a1so deposits 1arge eggs a n d s h o w s 1ecithotrophic deve10pment (Kurata， 1955). It c a n b e a s s u m e d that the 1ecithotrophic d e v e 1 0 p m e n t of P. 1αtirostris results in 10ca1 dispersa1 of the 1arvae because their habitat is restricted to seagrass beds (see Havenhand， 1995). T h e meaning of 1ecithotrophic deve1op-m e n t， therefore， might vary from species to species as a 1ife history strategy. More detailed studies are required to clarify the re1ationship between the 1ecithotrophic development and their habitats.

Acknow1edgements W e t h a n k T a k a m i c h i A n d o，

T a k e s h i m a A q u a r i u m， Gamagori， for he1ping u s to collect the ovigerous shrimps. W e a1so t h a n k Kazuyoshi Hashizume， Japan Sea Nationa1 Fisher-ies Institute， and Tomoyuki Komai， N atu-ra1 History M u s e u m and Institute， Chiba， for providing us with 1iterature. Specia1 gratitude is extended to Iwao Hidaka， Mie University， for his encouragement a n d comments o n the manuscript. T h e manu-script w a s improved b y c o m m e n t s of Tomoyuki K o m a i， Pau1 C1ark， N atura1 History M u s e u m， London. T h e Eng1ish text w a s read b y Peter Castro， California State Po1ytechnic University， Pomona.

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Berkeley， A. A.， 1930. T he post-embryonic de-velopment of the c o m m o n pandalids of British Columbia. Contributions of Cana-dian biology and fisheries. 6， 81-163.

Christoffersen， M. L .， 1989. Phylogeny and classification of the Pandaloidea-(Crusta-cea， Caridea). Cladistics， 5: 259-274.

Crain， J. A. 1999. Functional morphology of prey ingestion by Placetron wosnessenskii Schalfeew zoeae (Crustacea: Anomura: Lithodidae). Biological Bulletin 197: 207-218.

Gore， R. H.， 1985. Molting and growth in deca-pod larvae. In: A. M . Wenner (ed.)， Larval growth . Crustacean Issues 2， A. A.

Balkema， Rotterdam， 1-65. G u m e y， R.， 1942. Larvae of decapod Crusta-cea. Ray Society， London， 306 pp.

Havenhand， J. N .， 1995. EvolutionaIγecology of larval types. In: L. R. McEdward (ed.)， Ecology of marine invertebrate larvae. C R C press， Boca Raton， 79-122.

Haynes， E.， 1976. Description of zoeae of coonstripe shrimp， p，αndαlus hypsinotus， reared in the laboratory. Fishery Bulletin， 74(2): 323-342.

一一一一一一一， 1978. Description of larvae of the humpy shrimp， p ，αndalus goniurus， reared in situ in Kachemak Bay， Alaska. Fishery Bulletin， 76(1): 235-248.

一一一一， 1979. Description of larvae of the northern shrimp， Pαndulus borealis， reared in situ in Kachemak Bay， Alaska. FisheIγBulletin， 77(1): 157-173.

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Komai， T. & Mizushima， T.， 1993. Advanced larval development of P a n dαlopsis japonicαBalss， 1914 (Decapoda， Caridea， Pandalidae) reared in the laboratory. Crustaceana， 64 (1): 24-39.

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Williamson， D. I.， 1969. Names oflarvae in the D e c a p o d a a n d E u p h a u s i a c e a . Crustaceana， 16: 210-213.

Yamamoto， G.， Maihara， Y.， Suzuki， K. & Kasaoka， M.， 1982. Rearing of larvae of deep-sea Macruran Decapod， Pαn dαlus nipponensis Yokoya. Proceedings ofNorth Pacific Aquaculture Symposium， 329-334. (In Japanese)

Addresses: (HaT， HiT) Toba Aquarium， Toba 3・3・6，Mie， 517・8517 Japan; (KK) Na-tional Research Institute of Aquaculture， Nansei， Mie， 516-0193 Japan E-mail: (HaT)fvbc1007@ mb.infoweb.ne.jp;

(KK)kzoea@r凶a.affrc.go.j

H . T A I S H A K U E T A L.

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Days after hatching Fig. 1. A: Growth oflarvae and postlarvae of p，αndalus nipponensis Yokoya. M e a n value of cara-pace length and S D. B : N u m b e r of surviving larvae and postlarvae of p，αndalus nipponensis Yokoya. B': number of surviving larvae and postlarvae of Pandalus nipponensis Yokoya under non-feeding condition.

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 11

?、 A

B

Fig. 2. p，αndalus nipponensis Yokoya: A - F， carapace ofstages 1-6 in lateral view; A'， anterior part ofcarapace in doral view， showing short rostrum; B'-F'， abdomen ofstages 2-6 in lateral view. Scale = 1.0 m m .

12 H . T A I S H A K U E T AL.

A

Fig. 3. p ，αndαlus nipponensis Yokoya: A - D， left antennule ofstages 1-4 in ventral view; E-G， left antenna of stages 1-3 in ventral view. Scale = 1.0 m m .

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 13

Fig. 4. p，αndalus nipponensis Yokoya: A - C， mandibles ofstages 1-3 in external view; D - F， left maxillule of stages 1-3 in external view. Scale = 0.5 m m .

14 H . TAlSHAKU E T A L.

F

Fig. 5. p，αndαlus nipponensis Yokoya: AーC，left maxilla of stages 1-3 in external view; D - F， left maxilliped 1 of stages1-3 in external view. Scale = 0.5 m m.

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 15

H

J'ーL'Fig. 6. p ，αndαlus nipponensis Yokoya: A - C， left maxilliped 2 of stages 1-3 in external view， one ofnatatoIγsetae enlarged in fig. A; D-I， left maxilliped 3 ofstages 1-6， stage 1 in mesial view， stages 2-6 in lateral view， only basis in stages 4-6; J-L， left pereopod 1 of stages 1-3， stage 1 in mesial view， stages 2， 3 in lateral view; J'-L'， chela ofpereopod 1 ofstage 1-3 in lateral view. Scales = 1.0 m m for A - L， 0.1 m m for J-L'.

16 H. T A I S H A K U E T AL.

B A (right)

(left)

(right)

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Fig. 7. P a n dαlus nipponensis Yokoya: A - C， left and right pereopod 2 of stages 1-3， stages 1，2，3 (right) in mesial view， stage 3 Oeft) in lateral view. Scale = 1.0 m m .

L A R V A L D E V E L O P M E N T O F P A N D A L U S NIPPONENSIS 17

Fig.8.P，αndαlus nipponensis Yokoya: A - C， left pereopod 3 ofstages 1-3 in lateral view; D - F， left pereopod 4 of stages 1-3 in lateral view; G -I， left pereopod 5 of stages 1-3 in lateral view. Scale = l.O m m .

18 H . TAlS H A K U E T A L.

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fig， 9， Pandαlus nipponensis Yokoya: A-E， left pleopods of stage 3 in lateral view; F-J， left pleopods of stage 4 in ventral view; K - O， left pleopods of stage 5 in ventral view; P， left pleopod of stage 6 in ventral view. A， F， K， P， pleopod 1; B， G， L， pleopod 2; C， H， M ， pleopod 3; D， 1， N ， pleopod 4; E， J， 0， pleopod 5. Scale = 0.5 m m .

LARVAL DEVELOPMENT O F PANDALUS NIPPONENSIS 19

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Fig. 10. Pandalus n伊'/)onensis Yokoya: A - F， telson ofstages 1-6 in dorsal view. Scale = 1.0 m m .

20 H . T A I S H A K U E T AL.

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F

Pig. 11. p，αndαlus nipponensis Yokoya: A-F， right branchial chamber of stage 1-6. Scale = 1.0 m m.