Two new freshwater species of the genus Jesogammarus (Crustacea: Amphipoda: Anisogammaridae) from northern Japan

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ZOOLOGICAL SCIENCE 20: 229-241 (2003) @ 2003 Zoologica lSociety of Japan
TwoNew Freshwater Speciesof the Genus Jesogammarus

(CrustaceAmap:hipoda: Anisogammaridae)

from NorthernJapan

Ko Tomikawai 'and Hiros hMiorino2
i Diw'sio nof Biologica lSciences, Gradtiate School of Science ,Hokkaicio University;
Sapporo, 060-0810 tapan
2Department of Ehvironmental Sciences ,faculC )oft Science,
tbarakUiniversitMyi)to,310-8512Japan

ABSTRACT-two new anisogammarid species belongin gto the genus Jesogammarus were obtained
from freshwate rhabitat sfrom northern Japan. They are Jesogammarus CJ .f)ojin ospi. nov. and Jesoga-
mmarus (U, s)honaiensis sp, nov,, The former new species is diagnose bdy the pleonite wsithout spine and
the telso nwithout distolate rsapline, The other new specie$ diffe rfsrom the congeneric species in having
many dorsalspines on pleonite1-s3.

Key words: new species, Anisogammaridae ,Jesogarnmarus ,Taxonomy, Japan
{NSMT).
INTRODUCTtON
The genus Jesogammarus in the sense of Morino TAXONOMY

(1985 h)as been known from the northwestern Pacifi crim
regions including Japan, Korea and China (Mori n1o9,94), Jesogammarus (Uesogammaru tso)jino sip. nov.
To date i teontains 11 species within two subgenera that (Japane nsaeme: Fujino-yokoeb nie,w)
occur in cold fres hwaters to brackis hhabitat sT,his species (Fig s1-.5)
diversi tiys surely an underestimate when consider a poor Type $eries
knowiedge for the continental regions (Mori naond Dai, Holotype ,NSMT-Cr, 2757 (mal e1,3.6 mm, tO Oct.
1990) .This is also partl tyhe case in Japan, as some Japa- 2000, 4 microscope sljdes and 1 ethanol); paratypes,
nese species remain to be describe d(Bousfi e1l9d79,; NSMT-Cr. 2758 (alloty opvei,gerous female ,9.7 mm, 26 Jul.
Morino ,1985) ,and several areas of this country await inten- 2000, 10 microscope slides and 1 ethanol>, NSMT-Cr. 2759
sive taxonomical surveys. The senior author has carried out <mal e1,3.0 mm, 28 Aug, 2000, 3 microscope slides and 1
fie lsdtudies to clarify the fauna in northern Japan, inten- ethanol), NSMT-Cr, 2760 (mal e1,2,1 mm, 17 Nov. 2001, 1
sively in Yamagata Prefecture, The presen tstudy yielded ethanol), NSMT-Cr. 2761 (mal e1,2.7 mm, 10 Oct. 2000, 1
two new species in the $ubgenus Jesogamrriaru sas ethanol), NSMT-Cr. 2762 (mal e1,1.9 mm, 10 Oct, 2000, 1
describe dbelow. ethanol), NSMT-Cr. 2763 (mal e1,2,5 mm, 10 Oct, 2000, 1
ethanol), NSMT-Cr. 2764 {mal e1,0.2 mm, 10 Oct. 2000, 1
MATERIALSAND METHODS ethanol), NSMT-Cr. 2765 {fema l9e.,8 mm, 10 Oct. 2000, 1
ethanol), NSMT-Cr. 2766 (fema l8e.9, mm, 10 Oct, 2000, 1
The specimens were collected by scooping with a fin emesh ethanol), NSMT-Cr, 2767 (ovigero ufsemale ,9,O mm, 10
hand-net ,and fixe din 70% ethanol at the site, The body lengt hfrom Oct, 2000, 1 ethanol), and NSMT-Cr. 2768 (fema l8e.,9 mm,
the base of the fir satntenna to tha tof a telso nwas measured to 10 Oct, 2000, 1 ethanol}; Gobanmiki (38014'07"N,
tefahecehm an elaiernessdatinvd iOdg.ue1 anwlmaismt a pdblaeypt ieslrtlrmaaiifengoehrdt mebanyli etnsgh. eo Apuptr peeesanecdnhac gea enosif mbawrle.or eoTd hdpeil sassteeexc s ttooefrd s1p4ri0negl Of'r4o7m "MEt) ., YSahmiarnaotbaek-a cm,oallcehcite,dY abmya gKa. tTao mPirkeafweact.ure, a

and embedded in a gum-chlor maeldium on glas sslides. The type
material is deposit edin the Nation aSlcienc eMuseum, Tokyo Other materials
' Corresponding author:Tel.FAX . ++88t1--1111--770466--3e582642;. su ra -b1u4c himal es(,3 8101 2f0em'a3l7 es"t ,4N20 ,ej2u5v'4e4n"iE l) 1,eT9 esNn,odvo.- s2h0i0 ,0Y, amKaa-t-
E-mail:[email protected],ac,jp gata Prefecture, collected by K.Tomikawa; 4 males, 14 (2
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t.Jesogammarus "esogammaru tsL)u'i snpo, inov, Gobanmiki Y,amagata Pref .J,apan.Male 13.0 mm-paratype. Scaie 1: mm,
ovig.) females ,6 Feb. 2001, Benzaiten-shimi z(u38015'17"N,proximo-submarginal wliyth 2 groups of double spine$; arti-
140alO'45"E) ,Yamanobe-machi, Yamagata Pretecture, cle 3 92.2% lengt hof article 2, with 3 A-setae clusters and
collected by K, Tomikawa; 14 males, 28 (1 9ovig.) females, 1 B-setae cluster.
26 Apr. 2000, Ohira (38014'08 "1N40,"10'46"E) ,Yama- Right maxilla 1 (Fi g2.F, G}: palp article 2 with 4 setae
gata-sh iY,amagata Prefectur ec,ollected by K, Tomikawa: on outer margin, apically with 8 spine$ and 8 setae; outer
24 males, 10 ( 1ovig.) females ,13 Feb. 2001, Ohira plat eapically with 11 serrated spines; inner plat ewith 18
(38el3'sO 1"4N00,11'14"E), Yamagata-shi, Yamagata Pre- plumose setae medially.
fecture ,collected by K. Tomikawa; 22 males, 35 (4 ovig,) Lef tmaxilla 1: palp article 2 apically with 9 spines and
females, 17 juveni l9e Asp,r, 2001, Owarabi <38a13'51"N,8 setae; inne rplat ewith 23 plumose setae medially
140elO'47"E) ,Yamanobe-machi, Yamagata Prefectur eco,l- Maxill a2 (Fi g2H.): inner plat ewith 26 facia s[etae.
lecte dby K. Tomikawa. Maxillip e(dFi g2L.): inner plat e82.5% lengt hof outer
plate ,wlth 3 apicai spines and 3 medial bent spines; outer
Diagnosis plate79% lengthof palparticle2,medial marginal spines

Peduncula rarticle 1 of antenna 1 with 1 posterodistal closely set, a few dist aslpines pectinate.
spine, Pleonite s1-3 without spine. Urosomite s1 and 2 with Gnathopo d1 (Fi g3.A}: coxa weakly expanded distally,
closely-set spine clusters in the middle of dorsa lmargin, lower margin setulose, posterodist caolrner with 1 stif fseta,
urosomite 3 with a pai rof latera lspines and a pair of medial posteroproxim amlargin bare; postert oarnd anteroproximal
spine-cluster. Outer ramus of uropod 2' marginally bare, margins of basis with long setae; propod palmar margin
(Fi g3,B) line dwith 4 inne rand 9 outer striated peg spines,
Description ot male (holotype) anterior margin with 2 setae groups ;dacty laccessory blade
Head as long a$ deep. Eyes small, suboval. longe rthan nail, basall yelevated.
Antenna 1 (Fi g2.A): 45.2% of body length ;lengt hratio Gnathopod 2 (Fi g3.C): coxa lower margin setulose,
of peduncula rarticles 1-3 = 1i O.85 :O.45 ;peduncula rarticle posteroproxim amlargin bare ,posterodist acolrner with 1
1 with 1 posteromargin aslhort setal cluster, 1 seta and 1 spine; basis posteri oarnd anteroproximal margins with long
posterodist aspllne; articles 2 and 3 with 2 and 1 postero- setae, whjch are denser than those of gnathopod 1, antero-
marginal short setal clusters, respectively; flagellu m22- dista alngle with short setae; propod more slender than that
articulated; accessory flagellu 6m-aniculated. of gnathopo d1, palma rmargin <Fi g3.D} with 8 inner and 8
Antenna 2 (Fi g2,B, C): 72,O% length of antenna 1; outer striated peg spines; dacty laccessety blade ionger
peduncula rarticles 4 and 5 subequal in length, with 3 and 2 than nail, basall yelevated.
posteromargi nshaorlt setal clusters, respectively; flagellum Pereopod 3: coxa anterodistal margin setulose, poster-
13-articulate d,article s1-7 with cup-calceoli, odistal corner with 1 spine and stiff seta; basis posteri oarnd
Mandible (Fig .21-K) :lef tand right inciso r5s- and 4- anteroproximal margins with long setae, anterodistal margin
dentate ,respectively; lef tlacin jamobilis 4-dentate ,right with short setae; merus anterior margin with long spines,
lacini maobilis 2-edged; palp article 1 unarmed; article 2 with posteri omrargin with stM setae and long setae; carpus-pro-
11 marginal and 8 submarginal setae, 1 middle stif f$eta, pod posteri omrargins spinose and setose.
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Two New Jesogammarus fromJapan 231

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Fig.2. Jesogammarus "esogammaru sfiojin osip. nov. Gobanmiki, Yamagata Pref,, Japan. Male 13,6 mm-holotype. A: antenna 1; B:
antenna 2; C: calceofius of antenna 2 (1 ,2: flagell aarrticle 2, 3); D: upper lip ;E: lower lip ;F: right maxilla 1; G: dista lspines on outer plat oef
maxilia 1; H: maxilla 2; 1 :palp of lef mtandible; J: lef mtandible; K: inciso arnd lacini maobilis of right mandible; L: maxi[liped. Scale O:,50 mm for
A, B, D, E; O,25 mm for C, l-L ;O,30 mm for F, H; O.15 mm for G.
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232 K, Tomikawa and H.Morino
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Fig ,3. Jesogammarus (Uesogammaru sf)ttii nsop.i nov. Gobanmiki Y,amagata Pref, J,apan. Male 13,6 mm-holotype. A: gnathoped 1; B: pro-
pod palm and dacty lof gnathopod 1 ; C: gnathopod 2; D/ propod palm and dacty 1of gnathopod 2 ; E, F and G:abdominal side plate s1, 2 and 3;
H: pleopod 1; 1 :retinaculae of pleopod 1; J, K and L: postero-dorsa lmargins of pleonite s1, 2 and 3; M, N and O: postero-dor smaarlgins of
urosomites 1, 2 and 3, Scale: O.50 mm for A, C, J-O; O.25 mm for B, D; O.80 mm fo rE-H; O.15 mm fo rI.
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Two New Jesogammatus tromJapan 233

Pereopo d4: coxa posterodis tmaalrgin spinose, antero- setae, lower margin of posterio lrobe with tong stif fsetae;
dista mlargin setulose; basi sposteri oarnd anteroproximal basis anteroproximal margin with setae clusters ,anteredis-
margins with long setae, anterodistal angle with 1 spine; tal margin spinose, and with a few inne rfacia sletae; mar-
merus-propod posteri omrargin spinose and setose, merus gin sof meru$-propod spinose and setose,
anterior margin spinose and weakly setose, Pereopod 6 (Fi 4gB.): coxa anterior iobe with dista sltiff
Pereopod 5 (Fi g4.A): coxa anterior lobe with distal seta, lower margin of posterio rlobe with long stif fsetae;
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Fig. 4. Jesogammarus Qesogammaru sftitii snpo. inov, Gobanmiki Y,amagata Pref. J,apan, Male 13.6 mm-holotype. A, B and C: coxa-isch-
ium oi pereopod s5, 6 and 7; D, E and F: uropods 1, 2 and 3; G, H, l ,J, K and L: coxal gil lofs pereopod s2, 3, 4, 5, 6 and 7; M: telson. Scale:
O.50 mm for A-C; O.80 mm for D-L; O.45 mm forM.
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234 K. Tomikawa and H.Morino
basis anterior margin proximall ysetose, distal lsypinose, hal fof the basis of pereopod 7, accessory Iobe shorter than
posteri omrargin with spines and a few stiff setae, and with half of the main lobe.
inne rfacia sletae; margins of merus and carpus spinose and Pleonites 1-3: posterodor smaarglins (Fi g3J,-L) with 3
weakly setese; proped marginally spjnose and weakly set- $etules, 1O marginal and 1 submarginal setules, and 8 mar-
ose. gina land 6 submarginal setules, respectiveiy.
Pereopod 7 (Fi g4C.): coxa posterior margin with long Abdominal side plate s(Fi g3.E-G) posterior wliyth 1-5
stiff setae; basi sposter[o mrargin with spines and stif fsetae, setules, Plate s2 and 3 rectangular posterodista lPllya.t e1:
anterior margin proximall wyith long setae, distal lsypinose, anterior margin with ca. 18 long setae, ventral margin with
and inne rsurface with setal clusters. 2 long stiff setae. Plat e2: ventrally with 4 marginal and 2
Coxal gill sof pereepeds 2-4 (= gill s2-4)<Fig. 4G-1) submarginal slender spines. Plat e3: anterior to ventral mar-
subequal to bases of respective pereopods in length, poste- gin with 1 setule and 6 slender spines.
rior accessory lobes longe rthan anterior one and little Pleopods: peduncle swith outer marginal and facial
longe rthan hal fof the main lobes. Gil l5 <Fi g4.J) longer setae; inne rramus with 4 clothes-pin spines. Pleopod 1 (Fig,
than the basis. Gil l6 (Fig .4K) accessory lobe distinctly 3H, I) iouter ramus 24- ,inner ramus 19-articulat ePdl.eopod
longer than half ot the main Iobe. Gil l7 (Fi g4L.) shorter than 2: outer ramus 25- ,inne rramus 18-articulat ePdl,eopod 3:
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Fig.5. Jesogammarus "esogammatu sn4tiin osip. nov. Gobanmiki, Yamagata Japan. Female 9.7 mm-allotype. A: antenna 1; B:
antenna 2; C: gnathopod 1; D: propod palm and dacty lof gnathopod 1: E: gnathopod 2 F: propod palm and dacty olf gnathopod 2; G: brood
plate of gnathopo d2; H, 1 and J: coxa-ischium of pereopods 5, 6 and 7; K: uropod 3 Scale :O,80 mm for A-C, E, G; O.1O mm for D, F; O.50 mm
for H-K.
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Two New Jesogammarus fromJapan 235

outer ramus 24-, inner ramus 18-articulated. medial spine clusters on urosomites t and 2, (3 )expanded
Urosomit e1s and 2 (Fi g3.M, N) dorsomarginal lwyith bases of pereopod s5-7, and (4 )shorter marginal spines on
singie later aslpines and middle spine cluster of 9 spines, abdominal side plate$ T.he new species, however, is distin-
with interspers esdetae. Urosomite 3 {Fig 3.0) with a pai rot guished from J. (U. Jhokurikuensi sin having <1 )pleonites
later aslpines and a pair of medial spine-cluster, with inter- without dorsa lspines, (2 )marginally bare outer ramus of
spersed setae. uropod 2, and {3 )telson without distolate rsapline.
Uropod 1 <Fi g4.D): outer ramus 66.7% lengt hof pedun- Jesogammarus ". )fojin osip. nov. is also similaf to J.
cle; peduncle with marginal spines and 1 basofacia slpine; aJ .J)'esoen sSicshellenmerg ,1937 in having (d )1 distal
outer and inner ramus with 1 marginai spine, respectively. spine of peduncula rarticle 1 of antenna 1, (2 )short and a
Uropod 2 (Fi g4,E): peduncle with marginal spines; few setal clusters of peduncula rarticles 4 and 5 ot antenna
outer ramus marginally bare; inner ramus with 1 outer and 2, and (3 )shorter telson J.esogammarus ". )tLiji nspo,i nov.
1 inner marginal spine, is ,however, distinguish ferdom J, (U, i)esoens iisn having O)
Uropod 3 (Fi g4.F): outer margin of outer ramus with 2 expanded bases of pereopods 5-7, (2 )pleonjte swithout
spine clusters and a few plumose and simple setae, inner dorsa slpines, (3 )shorter marginal spines on abdominal side
margin of outer ramus with 4 spine clusters and many plu- plate s(,4 )closely-set medial spine clusters of urosomites 1
mose satae; terminal article distin c, t23.8% Iengt hot prox- and 2, and (5 )telson without distolate rsapilne.
imal article; inne rramus 20.7% lengt hof outer ramus, with
apical and medial plumose setae. Etymology
Telson {Fi g4,M): lengt h83.0% of basal maximum The species is named in honor of Prof ,Takahiro Fujino
width, each lobe with 1 apical spine and distolatera sletae. of Yamagata Univer$it ywh,o ied the senior author to this
study.
Female (allotype)

Antenna 1 (Fi g5A.): lengt hratio of peduncula rarticles Distribution
1-3=1: O.69 :O.35 ;peduncula rarticle 1 with 2 posteromar- This new species is collected from mountain springs
gina lshort setae and 1 posterodist sapline; artjcles 2 and 3 and spring brooklet saround Mt. Shiratak aand Mt. Amay-
with 2 and 1 posteromargin aslhort setal clusters, respec- obari ,Yamagata Prefectur eT.he water temperature of the
tivel yf;lagellu 2m4-articulated ;accessory flage-um 4-articu- spring of the type localit yis 9,O-9.5eC throughout the year.
lated. Mature adults are found at all seasons of the year in this
Antenna 2 (Fi g5.B): length ratio of peduncul aarrticles place,
4: 5=1: O,85, peduncula rarticles 4 and 5 with 2 long setal
clusters posteromarginal lrye$,pectively; flagellu m11-articu- lesogammarus tUbsogammaru ssho)naiensis sp,nov,
lated, di$ta alrticles with medium long setae posteriorly, (Japane snaeme: Shonai-yokoeb in,ew)
Gnathopod 1 (Fig 5.C): coxa with 12 setae on postero- (Fig s6-,9)
proxim amlargin; basis with several facia sletae; propod pal-
mar margin (Fi g5D.>, posterodis tamalrgin with 10 simple Eogammarus jesoensi sK:araman, 1979, pp. 34-38,
spines; dacty lposterio arccessory blade mvch shorter than figs ,5-7. (i npart ,specimens only from lshikawa)
nail, basall ynot elevated. Jesogammarus sp.: Bousfiel d1,979, pp, 335-336,
Gnathopod 2 (Fi g5E,): coxa posteroproxim amlargin Jesogammarus (Vesogammar sups.:) Morino, 1985, p.
with 21 setae; carpus and propo dslender; propod parallel- 34,
sided, propod palmar margin (Fi g5,F), outer di$ta mlargin
with 5 pectinat espines, inner distal lwyith 3 simple and 3 Type series
pectinat espines; dacty 1posterio brlade much shorter than Holotype, NSMT-Cr. 2769 (mal e1,7,9 mm, 6 micro-
nail, basall ynot elevated. scope slides and 1 ethanol); paratypes ,NSMT-Cr. 2770
Bases of pereopods 5-7 (Fi g6.H-J) more expanded (alloty jpuev,eni fleemale ,12.8 mm, 5 micrescope slides and
posteroproxima ltlhyan those of male. 1 ethanol), NSMT-Cr. 2771 (mal e1,4,9 mm, 5 microscope
Brood plat eot gnathopod 2 (Fi g5G.) }arge and broad, slides and 1 ethanol), NSMT-Cr, 2772 (mal e1,4.5 mm, 1
expanded anteroproximal:y ,fringe dwith numerous setae . ethanol), NSMT-Cr. 2773 (male ,12.4 mm, 1 ethanol),
Uropod 3 (Fig ,5K}: termina tarticl eof outer ramus NSMT-Cr. 2774 (fema l1e3,.0 mm, 3 microscope slides and
23.4% lengt hof proxima larticle; inner ramus 22.8% iength 1 ethanol), NSMT-Cr. 2775 <fema l1e3.,3 mm, 2 microscope
of outer ramus, slides and 1 ethanol), NSMT-Cr. 2776 (tema l1e1.,1 mm, 1
Egg number: 26, ethanol>, NSMT-Cr. 2777 (fema l1eO,.3 mm, 1 ethanol), and
NSMT-Cr. 2778 (fema l1e1,,9 mm, 1 ethanol); Kuromori
Remarks (38"50'45" 1N3,9'48'53nE), Sakata-sh iY,amagata Pref. a,
Jesogammatus Uesogammatu sftitii nspo.i nov. is sim- spring brookle tin the Shonai distri c7t ,Nov. 2001, collected
ilartoJ.".)hokurikuensisMorino,1985 inhaving(1)1dis- byK,Tomikawa.

ta lspine of peduncul aarrticle 1 of antenna 1, (2 )closely-set
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236 K. Tomikawaand H.Morino
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Fig. 6, Jesogammarus "esogammaruE) shonaiensis sp, nov, Kuromori ,Yamagata Pref, J,apan, Female 13,3 mm-paratype. Scale: 1mm.
Othermaterials accessory flagellu m6-adiculated.
33 males, 43 (5 ovig.) females ,17 Nov. 2001,JimotoPref e c- Antenna 2 (Fi g7D., E): peduncul aarrticle 5 85% Iength
(3805'30 "1N3,9023'23"E> ,Nakajo-machi ,Niigata of article 4, both article sbearin g3 short setal clusters on
ture, collected by K, Tomikawa. posteri omrargin; flagellu m19-articulat epdr,oxima l10 arti-
cles with cup-calceoli,
Diagnosis Mandible (Fi g8.F-H): lef tand right incisors 5- and 4-
Peduncular articl e1 of antenna 1 with 1 posterodistal dentate ,respectively; lef tlacini amobilis 4-dentat e,right
spine. Articl e1 of mandible palp unarmed, article 2 with lacin imaobilis 2-edged ;palp article 1 unarmed; palp article
proxima lspines. Pleonite$ 1-3 dorsomarginal lwyith spines 2 with 7 marginal and 18 submarginal setae, 1 group of dou-
and setae. Urosomite s1 and 2 with separated spine clusters ble spines; palp article 3 subequal to article 2 in length, with
in the middle ot dorsa lmargin. Telson longe rthan basal 5 A-seta lclusters, 1 seta, and 2 B-setal clusters.
maximum width, Right maxilla 1 (Fi g71., J) :pal particl e2 with 5 setae on
outer margin , and with 7 spines and 8 stif fsetae distally;
Descrjptio nof male {holotype) outer plat eapica[ly with 11 serrated spines; inner plat ewith
Head as long as deep. Eyes small, subreniform. 21 plumos esetae medially.
Antenna 1 (Fi g7,C): 51% of body length I,engt hratio of Left maxilla 1: palp article 2 with 6 setae on outer mar-
peduncula rarticles 1-3=1: O.80: O.38; peduncular article 1 gin ,and with 1O spines and 9 stiff setae distal liyn;ne rplate
with 1 posteromargin ashlort setal clusters, 2 setae, 3 setules, with 22 plumose setae medially,
and 1 posterodista lspine; article 2 with some posteromar- Maxill a2 (Fj g7K.): inne rplat ewith 25 facia sletae.
gina lshort setal clusters ;articl e3 with 1 posteromarginal Maxillip e(dFi g7,L: distort eadt the juncti oofn palp}:
short setal cluster and 1 seta; flagellum 36-articuiated; inner plat eshorter than outer plate ,with 3 apical spines and
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TThhee ZZoooloolgiocaglical SSoociceityety ooff JJaapapnan
Two New Jesogammarus tromJapan 237

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Fig. 7. Jesogammarus aJesogammar ushson)aiensis sp. nov. Kuromori, Yamagata Pref. ,Japan. Male 17.9 mm-holotype, A: upper iip ;B:
lower lip C;: antenna 1; D: antenna 2; E: calceolus; F: palp of lef mtandible; G: let mtandible; H: inciso rand lacini maobili$ of right mandible; 1:
right maxilla 1; J: dista lspines on outer plate of maxilla 1; K: maxilla 2; L: maxilliped; M: pleopod 1; N, O and P: coxal gil lofs pereopod s7, 6
and 5; Q, R and S: abdominal sjde plate s1, 2 and 3. Scale :O.74 mm for A-D, M-S; O,15 mm for E, J; O,38 mm for F-1 ,K; O.30 mm for L
3 medial bent spines; outer plat esubequal to pal particl e2 with long setae; propo dpalma rmargin with 14 and 11 stri-
in length ,medial $pines closely set, a few dista lspines ated peg-spine son inner and outer margins, respectively;
weakly pectinate, dacty laccessory blade longe rthan nail, basall yelevated,
Gnathopod 1 (Fi g8A., B): coxa, lower margin setulose Gnathopod 2 (Fi g8C., D): setation of coxa and basis as
with t spine on posterio rcorner, posteroproxim amlargin those of gnathopod 1; propod palmar margin with 11 and 7
with 4 setae; basis anteroproximal and posteri omrargin$ striated peg-spine son inner and outer margins, respec-
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TThhee ZZoooloolgiocagliSoccaielty Society ooff JJaapapnan
238 K, Tomikawa and H.Morino
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Fig. 8. Jesogammarus aJesogammar suhson)aiensis sp. nov. Kuromori, Yamagata Pref. J,apan. Male 17.9 mm-holotype. A: gnathapo d1 ; B:
proped palm and dacty olf gnathepod 1; C: gnathopod 2; D: propod palm and dacty olf gnathopod 2; E, F and G:uropod s1,2 and 3; H,1and
J: postero-dors amlargins of pleonite s1, 2 and 3; K, L and M:postero-distal margins of urosomites 1, 2 and 3; N: telson ,Scale: O,74 mm forA,
C, E-G; O.30 mm for B, D; O.50 mm for H-N.
tivel yd;acty l(Fig .8D) accessory blade longe rthan nail, seta; basis weakly expanded posterior lbye,arin g2 inner
basall yelevated, facia sletal clusters, posteri omrargin with spines and stiff
Pereopod 4: coxa, posteri omrargin almost vertical. setae, posteredist allobe weak.
Pereopod 5 (Fi g9.A) :coxa anterior lobe with 1 distal Pereopod 6 (Fi g9B.>: coxa anterior lobe witheut distal
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