New records of two species of Platambus optatus species-group (Coleoptera, Dytiscidae) from Hokkaido, Japan

2010·0.07 MB·

by  Okada, Ryohei

Elytra,Tokyo,38(1):27(cid:2)28,May31,2010
New Records of Two Species of Platambus optatus Species-group
(Coleoptera, Dytiscidae) from Hokkaido, Japan
Ryohei OKADA
LaboratoryofMarineBiologyandBiodiversity(SystematicIchthyology),
GraduateSchoolofFisheriesSciences,HokkaidoUniversity,3(cid:2)1(cid:2)1
Minato-chˆo,Hakodate,Hokkaido,041(cid:2)8611Japan
Platambus optatus species-group was redefined by N>AHHDC (1996) and four species, P.
ikedai,P.optatus,P.stygiusandP.insolitushavebeenrecordedfromJapan(N>AHHDC,2003). Up
to the present, only P. stygius has been known from Hokkaido (MDG> & K>I6N6B6, 2002).
Recently, I found two species of this species-group, P. ikedai and P. optatus, from Oshima
Peninsula, southwestern Hokkaido, Japan. In this paper, I record them for the first time from
Hokkaido.
Beforegoingfurther,IwishtoexpressmyheartythankstoNaoyukiH>@>96(Mito)forhis
identification of these species and valuable comments. Thanks also go to Dr. Hiroyuki
YDH=>IDB> (EhimeUniversity) forhisvaluableadvice andcritical readingofthismanuscript.
Platambus ikedai (N>AHHDC, 1996)
(Fig.1)
Agabussp.:I@:96,1994,38[Mt. Chˆokai].
Agabusikedai:N>AHHDC,1997,684[type locality:Mt. Chˆokai,Honshu,Japan].
Platambusikedai:N>AHHDC,2000,34.
Specimens examined. [Hokkaido] 1(cid:2), 1(cid:3), Zendana, Kaminokuni-chˆo, 28(cid:2)IV(cid:2)2007; 8(cid:2)(cid:2),
3(cid:3)(cid:3),samelocality,12(cid:2)IX(cid:2)2009;1(cid:2),1(cid:3),Yunotai,Kaminokuni-chˆo,21(cid:2)X(cid:2)2007;2(cid:3)(cid:3),Himekawa,
Otobe-chˆo, 29(cid:2)IV(cid:2)2008; 1(cid:2), 1(cid:3), Marunuma, Shikabe-chˆo, 13(cid:2)VII(cid:2)2008; 3(cid:2)(cid:2),«Onuma, Shikabe-
chˆo,31(cid:2)V(cid:2)2009;9(cid:2)(cid:2),11(cid:3)(cid:3),samelocality,4(cid:2)IX(cid:2)2009. AllspecimonsarecollectedbyR.O@696.
Distribution. Japan:Hokkaido(new record), Honshu(Mt. Chˆokai).
Notes. Diagnosis of this species by N>AHHDC (1996) is that the median lobe with slight
subapical constriction and without or with less than two ventrodistal spiniform setae. In the
specimensfromHokkaido,however,themedianlobesofmalegenitaliaaremoreweaksubapical
constrictionandnosetae.
Platambus optatus (S=6GE, 1884)
(Fig.2)
AgabusoptatusS=6GE,1884,445[typelocality:Kishu,Honshu,Japan];N>AHHDC,1996,635
28 RyoheiO@696
Figs.1(cid:2)2. Median lobesofmalegenitalia ofPlatambusspp.inlateralview.(cid:3)(cid:3)1,Platambusikedai
from«Onuma,Shikabe-chˆo;2,PlatambusoptatusfromYabuchi,Setana-chˆo.Scale:0.5mm.
[Honshu,Kyushu,Shikoku].
Platambus optatus: N>AHHDC, 2000, 34; K>CD & H6H:<6L6, 2001, 24 [Hachijˆo Is.];
N>AHHDC,2003,268[FujianandJiangxi,China].
Specimens examined. [Hokkaido] 2(cid:2)(cid:2), Uriya, Kikonai-chˆo, 28(cid:2)IV(cid:2)2007; 1(cid:3), Tomisato,
Assabu-chˆo,19(cid:2)VII(cid:2)2007;1(cid:2),1(cid:3),Yunotai,Kaminokuni-chˆo,21(cid:2)X(cid:2)2007;2(cid:2)(cid:2),2(cid:3)(cid:3),Katsu-
raoka,Kaminokuni-chˆo,12(cid:2)IX(cid:2)2009;1(cid:2),1(cid:3),Yabuchi,Setana-chˆo,26(cid:2)IX(cid:2)2009.Allspecimens
are collected byR.O@696.
Distribution. Japan:Hokkaido(newrecord),Honshu,Kyushu,Shikoku,HachijˆoIs.;China:
Fujian,Jiangxi.
Notes. This species shows geographical variation (N>AHHDC, 1996). The above specimens
have a relatively slender median lobe in lateral view, and its feature is similar to those from
Honshu(N>AHHDC,1996:Fig.20).
References
I@:96, T., 1994. Collecting record of Platambus optatus species-group from Mt. Chokai, Yamagata Pref.
Gekkan-Mushi,Tokyo,(279):38.(InJapanese.)
K>CD,N.,&H.H6H:<6L6,2001.DistributionofJapanesePlatambusoptatusspecies-group.Coleopterists’
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