Bull. Natl. Mus. Nat. Sci., Ser. A, 38(1), pp. 21–32, February 22, 2012

Arge enkianthus n. sp. (Hymenoptera, Argidae) Feeding on
Enkianthus campanulatus in Japan
Hideho Hara1 and Akihiko Shinohara2
1

Forestry Research Institute Doto Station, Hokkaido Research Organization,
Shintoku, Hokkaido, 081–0038 Japan
E-mail: hara-hideho@hro.or.jp
2
Department of Zoology, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki, 305–0005 Japan
E-mail: shinohar@kahaku.go.jp(Received 15 November 2011; accepted 28 December 2011)

Abstract Arge enkianthus n. sp. is described from Honshu and Shikoku, Japan. Larvae are gregarious leaf feeders on Enkianthus campanulatus (Miq.) G. Nicholson (Ericaceae). Descriptions of
the immature stages and notes on the life history are also given. This is the ﬁrst record of sawﬂy
associated with Enkianthus.
Key words : Argidae, Arge enkianthus, new species, Enkianthus, Japan.

During our studies on the taxonomy and biology of the Argidae in Japan, we came acrossstrange argid larvae gregariously feeding on theleaves of Enkianthus campanulatus (Miq.) G.
Nicholson (Ericaceae) in Miyagi, Kanagawa andNagano prefectures, Honshu, almost simultaneously at the end of July, 2006. The larvae of thesame species were subsequently discovered in
Tochigi prefecture in 2008. We were able to obtain
the adults by rearing the larvae and found thatthey belong to an undescribed species of Arge.
Only several adult specimens of this species havebeen collected aﬁeld so far in Tochigi, Kanagawa,
Nagano and Shiga prefectures, Honshu, andKochi prefecture, Shikoku.
Here we describe and illustrate the new species of Arge and give notes on its life history.
This is the ﬁrst record of Enkianthus as a hostplant of sawﬂies.

Leica MS5 stereo binocular microscope andmeasurements of each structure were taken withan ocular micrometer. Photographs were takenwith digital cameras, Canon EOS Kiss Digital,
Konica Minolta DiMAGE A200X, Panasonic
DMC-FZ30 and Ricoh Caplio GX100, Keyence
Digital Microscope VHX-900 and AnMo Electronics Dinolite digital microscope. The digital
images were processed and arranged with Adobe
Photoshop Elements 7.0 software.
Rearings were made in a room without airconditioning in Bibai by Hara and in an air-conditioned room in Tokyo by Shinohara. In therearing rooms, the temperature was usually
18–25°C and the light was usually on for about
16 hours a day.
Results
Arge enkianthus n. sp.

Materials and Methods
The material used in this work is kept in the
National Museum of Nature and Science, Tsukuba, unless otherwise stated.
Observations of morphology were made with a[Japanese name: Dodan-churenji](Figs. 1–5, Table 1)

Female (Fig. 1A, B). Length 7.5–9.5 mm.
Black or blackish brown, with weak blue reﬂection; clypeus with purplish reﬂection; basal and22

Hideho Hara and Akihiko Shinohara

Arge enkianthus n. sp. from Japan

middle abdominal terga with faint purplish
reﬂection. Flagellum brown to black, with colorless reﬂection. Labrum black. Mandible black,apically reddish. Palpi brown to dark brown.
Legs dark brown to black, with colorless reﬂection; fore and mid femora yellowish apically,hind femur brownish apically; tibiae yellowish
white, fore and mid tibiae narrowly brownish to
blackish apically and hind tibia brown to black
on apical third to fourth; tibial spurs brown to
black; tarsi brown to black, usually more or lesspale on basal parts of one to three basal tarsomeres. Wings hyaline, faintly yellowish or
brownish; forewing with black band below
stigma, extending to posterior margin of forewing but much weakened below vein M; stigma
brown to black, narrowly pale basally and apically; veins brown to black, yellow on C, Sc andapical section of R1; section of R1 basal tostigma yellow to dark brown. Subanal area pale
brown to black centrally. Setae generally whitish
or yellowish, brownish on sawsheath.
Surface generally smooth and shining; punctures on anterior part of head ﬁne, generally separated from each other.
Head in dorsal view (Fig. 2A) very slightly
concave at outer orbits, with width across eyes
about as long as width at genae. Distance
between eyes 1.1–1.3× vertical diameter of eye;eye with vertical diameter 1.6–1.8× horizontal
diameter. Postocellar area slightly convex, withanterior and lateral furrows indistinct (Fig. 2A),
rarely lateral furrow distinct as in Fig. 2B. Ocellar area slightly concave between ocelli (Fig.
2D–G). Frontal area usually concave deeply andsemicircularly before front ocellus medially andshallowly so anteriorly (Fig. 2D, G), sometimes
not concave anteriorly (thus, frontal area anteri-

23

orly ﬂat) (Fig. 2E), or rarely deeply concave
throughout (Fig. 2F); lateral ridges almost parallel, not or slightly raised anteriorly. Distance
between median fovea and front ocellus 1.7–
2.8× diameter of front ocellus. Median fovea
shallow to rather deep, with or without smallround tubercle (Fig. 2H–K). Interantennal carinae sharp, dorsally becoming dull, usually
curved medially and becoming low (Fig. 2H, I),
rarely not curved (Fig. 2J), and ventrally fused
together into median supraclypeal carina (Fig.
2C) above or at middle of supraclypeal area.
Supraclypeal carina sharp; side slope weakly
rounded and more or less rugulose laterally.
Malar space 0.6–0.9× width of front ocellus.
Clypeus distinctly sunk below supraclypeal
carina, then almost ﬂattened ventrally, with ventral margin deeply or moderately and roundly
concave medially (Fig. 2C). Antennal length 1.4–
1.6× maximum width of head; ﬂagellum
slightly compressed, curved basally and narrowly
rounded at apex (Fig. 2L, M). Right mandible
not incised on inner margin (Fig. 2C).
In forewing, cell 1Rs2 with anterior length
1.3–1.7× posterior length, and crossvein 3r-m
distinctly oblique, curved anteriorly (Fig. 1A); in
both wings, wing margin between veins Rs andCu scarcely or sparsely ciliate, with marginal
glabrous area narrower than width of vein M andmarginal setae slightly longer than width of vein
M (Fig. 2P).
Abdomen with second to fourth terga nearly
glabrous above; ﬁfth tergum anteromediallywidely glabrous or with very sparse minutesetae; sixth and more posterior terga setose,
except for narrow anteromedial part of sixth glabrous or with sparse minute setae. Seventh sternum with posterior margin weakly roundly pro-

Fig. 1. Arge enkianthus n. sp. — A, B, Female, holotype, dorsolateral and ventral views; C, male, paratype, Hakone,
dorsolateral view; D, ovipositing female, photographed in Nikko on 31 July 2011; E, rows of remains of egg shells,
Osaki, photographed indoors on 5 August 2006; F, young larvae, Osaki, photographed indoors on 6 August 2006;
G–H, ﬁnal and semiﬁnal instar larvae (HH060731B), Osaki, photographed indoors on 3 August 2006; I, group of larvae (AS080706A), early instar, photographed in Nikko on 6 July 2008; J, do., ﬁnal instar, photographed indoors on
15 July 2008; K, young larvae and infested leaves, photographed in Nikko on 17 August 2010; L, M, semiﬁnal andﬁnal instar larvae (AS060722A) photographed in Hakone on 22 July 2006; N, ﬁnal instar larvae (AS060728B) photographed in Hara-mura on 28 July 2006. D, I–N, photographed by A. Shinohara; E–H, photographed by H. Hara.

24

Hideho Hara and Akihiko ShinoharaFig. 2. A, B, Head, dorsal view; C, lower medial part of head, anterior view; D–G, ocellar and frontal areas, dorsal view;
H–K, frontal and interantennal areas, anterior view; L, M, female antenna, inner lateral and ventral views; N, O, maleantenna, inner lateral and ventral views; P, apical margin of forewing (small M means vein M). — A, D, H, L, M, P,
Holotype; B, G, K, N, O, male paratype, Hakone (N, O reversed image); C, female paratype, Hakone; E, I, female
paratype, Hakone; F, J, female paratype, Takayama-mura.

duced at middle. Sawsheath dorsally nearly ﬂat(Fig. 3A, B) or weakly convex (Fig. 3C) except
for basal concavity, in posterodorsal view longer
than wide, with lateral margin weakly convex(Fig. 3A–C), apex nearly pointed, medial margin
edged basally, and basal median lobe small, in
lateral view with ventral margin except for basal
convexity, weakly and roundly convex, some-times slightly and roundly concave midapically,
dorsal margin straight, and apex nearly pointed(Fig. 3D); inner surface spinose.
Lance with several linear membranous areas(Fig. 3E) and group of minute setae along ventral
margin at middle (Fig. 3G); apical crest ﬁnely
serrate on dorsal margin (Fig. 3F). Lancet withdorsal margin weakly roundly convex (Figs. 3H,

Arge enkianthus n. sp. from Japan

25

Fig. 3. A–C, Sawsheath, posterodorsal view; D, do., lateral view; E, lance; F, apical part of lance; G, ventral part of middle of lance; H, lancet (reversed image; numerals each indicate serrula number); I, do., seventh and eighth serrulae.
— A, D–I, Holotype; B, paratype, Takayama-mura; C, paratype, Hara-mura.

4A–C) or straight (Fig. 4D), and ventral marginroundly convex midapically, ventrally weakly
serrate basally and ﬂattened midapically, with
about 19–22 serrulae, dorsoapically with nonannulate area very narrow or indistinct; marginal
sensillae long; dorsal membranous areas withgroups of minute setae at intervals; wide longitudinal rows of setae present between annularplates and before ﬁrst annular plate; ﬁrst and second annular plates not reaching dorsal margin oflancet; middle annular plates with three to six
sensory pores except for ventral ones; apicalannuli arched toward base of lancet; serrulae
ﬁnely dentate (Fig. 3I).
Male (Fig. 1C). Length 6.5–9.0 mm. Coloration as in female, but ﬂagellum brown to darkbrown; wings often darker; genital capsulemostly dark brown. Head in dorsal view withwidth across eyes often slightly longer thanwidth at genae. Postocellar area often with dis-26

Hideho Hara and Akihiko ShinoharaFig. 4. Lancet, paratypes (numerals each indicate serrula number). — A, Osaki; B, Nikko; C, Hara-mura (reversed
image); D, Takayama-mura.

tinct lateral furrow (Fig. 2B), very rarely with
distinct anterior furrow. Frontal ridges sometimes
weakly converging anteriorly (Fig. 2G). Antennal
length 2.0–2.1× maximum width of head; ﬂagellum narrow and not compressed, in innerlateral view gently curved and very slightly narrowing toward apex (Fig. 2N), in ventral viewnearly straight with same width throughout androunded apically (Fig. 2O). In forewing, cell
1Rs2 with anterior length 1.1–1.5× posterior
length, and crossvein 3r-m as in female or gently
curved throughout. Abdomen with ﬁfth tergum or
its posterior half and more posterior terga withminute setae. Subgenital plate with posterior

Arge enkianthus n. sp. from Japan

27

Fig. 5. Male genitalia, paratypes. — A, Dorsal view; B–D, ventral view; E–G, penis valve, lateral view (left dorsal); H,
valviceps, lateral view (left dorsal). — A, B, E, H, Hakone; C, F, Osaki; D, G, Hara-mura. Abbreviations: dp, dorsal
apodemal projection; ll, lateral lobe; vl, ventral lobe.

Fig. 6. Final instar larva, Naruko. — A, Antenna, frontal view; B, C, ﬁrst to third abdominal segments, lateral and dorsal
views; D, E, eighth to tenth abdominal segments, lateral and dorsal views.

margin broadly rounded in ventral view. Genitalia as in Fig. 5; gonostipes in ventral view moreor less narrowing apically and apical widthslightly wider than basal width of harpe (Fig.
5B–D). Harpe in dorsal view narrow, withmedian margin nearly straight, lateral margin28

Hideho Hara and Akihiko Shinohara

rounded near apex, and apex pointed. Valviceps
in dorsal view (Fig. 5A–D) apically narrow,basally convex laterally, in lateral view (Fig.
5E–H) with dorsal margin roundly concave andapex narrowly rounded, basally with large ventral lobe (vl), small dorsal apodemal projection(dp) and ﬂat lateral lobe (ll) (Fig. 5C, H); laterallobe (ll) directed ventrolaterally, in lateral view
with ventral margin rounded.
Larva (Figs. 1F–N, 6). Coloration showing
geographical variations. Osaki population: Early
to semiﬁnal instars (Fig. 1F–H): Head black
except for ventral part brownish and legs whitish,
widely or only basally brownish to blackish;trunk pale creamy white; semiﬁnal instar with
10th abdominal tergum apically black. Finalinstar (Fig. 1G–H): Head yellow with very large
spot on vertex and large spot on frons black;trunk pale creamy white, yellowish on eighth andapex of 10th abdominal segments, each segmentwith three rows of black spots, subspiracular lobe
without black spot or some basal ones each withvery small black spot; thoracic legs almost whitewith black bases. Nikko population: Early instar(Fig. 1I): Head, thorax and thoracic legs pale
pinkish white except for black eyes and brownish
apex of mandible, and abdomen pale creamy
white (infested greenish leaf inside visible fromoutside) and slightly yellowish on eighth andapex of 10th abdominal segments. Middle instar:
Head creamy, trunk pale creamy white, yellowish
on eighth and apex of 10th abdominal segments.
Final instar (Fig. 1J): Head creamy, with large
spot on vertex and pair of small spots on frons
black; legs white with narrow black bases; trunk
white, orange on eighth to 10th abdominal segments, dorsal black spots relatively small andinconspicuous on ninth and basal half of 10th
abdominal segments, subspiracular lobe without
black marks, and apical half of 10th abdominal
tergum black. Hakone population: Semiﬁnal
instar (Fig. 1L): Head pale yellow, trunk palecreamy white, yellowish on eighth and apex of
10th abdominal segments. Final instar (Fig. 1L,
M): Similar to Osaki specimens, but thoracic legs
mostly blackish except for membranous areas,

black spots on dorsum of trunk larger and moredeveloped throughout, and subspiracular lobe
largely marked with black. Hara-mura population: Semiﬁnal and ﬁnal instars: Similar to
Hakone specimens, but ﬁnal instar (Fig. 1N)
black marks on subspiracular lobes smaller. In all
populations, setae on trunk generally pale inearly to semiﬁnal instars, generally brownish to
blackish in ﬁnal instar.
Structure (ﬁnal instar): Length 15–17 mm;
antenna conical (Fig. 6A); clypeus with two pairsof setae; labrum with two pairs of setae; mandible with two or three setae on outer surface;maxillary palp with four palpomeres; palpifer
with four to six setae; labial palp with three palpomeres; ﬁrst to ninth abdominal segments eachwith three annulets (Fig. 6B–E); prolegs on second to sixth and 10th segments (Fig. 1G), thoseon second to sixth elongate (Fig. 6B); dorsal
black spots each with one seta, except for dorsomedial fused spots each with pair of setae (Fig.
6); 10th tergum in dorsal view very broadly
rounded or nearly truncate apically (Fig. 6D);
subanal lobe slightly extending posteriorly
beyond suranal lobe (Figs. 1G, J, 6E).
Cocoon. Creamy, rarely almost white. Length
10–12 mm. Elongate oval, double walled; outerwall netted; inner wall parchment like.
Distribution. Japan (Honshu, Shikoku).
Material examined. Holotype (Fig. 1A–B): ♀,labeled “[JAPAN: Honshu], Owakudani, Hakone,
1020 m, Kanagawa Pref., larva coll. 22. VII.
2006, made coc. 25. VII., em. 27. IX. 2006,
AS060722A, Host: Enkianthus campanulatus, A.
& N. Shinohara”. Deposited in the National
Museum of Nature and Science, Tsukuba. Paratypes: Honshu: Miyagi Pref. – 5♀2♂, Osaki,
Onikobe, ca. 300 m, from 16 gregarious larvae(HH060802F), coll. 2. VIII. 2006, made coc.
9–12. VIII, em. 24. VIII–8. IX. 2006, Host: Enkianthus campanulatus, H. Hara; 1♀2♂, Osaki,
Naruko, 250–300 m, from 15 gregarious larvae(HH060731A), coll. 31. VII. 2006, made coc.
9–10. VIII, em. 24. VIII. 2006, Host: Enkianthus
campanulatus, H. Hara; 12♀5♂, do., but from45 gregarious larvae (HH060731B), coll. 31. VII.

Arge enkianthus n. sp. from Japan

2006, made coc. 5–7. VIII, em. 19–25. VIII.
2006; 4♀2♂, do., but from 20 gregarious larvae(HH060802C), coll. 2. VIII. 2006, made coc.
6–8. VIII, em. 22–27. VIII. 2006; 9♀4♂, do.,but from 19 gregarious larvae (HH060802D), coll.
2. VIII. 2006, made coc. 6–8. VIII, em. 22. VIII.
— 8. IX. 2006; 2♀3♂, do., but from 22 gregarious larvae (HH060802E), coll. 2. VIII. 2006,
made coc. 9–10. VIII, em. 26–27. VIII. 2006;
2♀1♂, do., but from 5 gregarious larvae(HH060804B), coll. 4. VIII. 2006, made coc.
6–7. VIII, em. 24. VIII.–8. IX. 2006. Tochigi
Pref. — 1♂, Nasu, Sandogoya, 25. VII. 1970, T.
Saito; 9♀, Hanaishi-cho, Nikko, ca. 640 m, fromgroup of larvae (AS080706A), coll. 6. VII. 2008,
matured 14. VII., em. 30–31. VII. 2008, Host:
Enkianthus campanulatus, A. and N. Shinohara;
8♀, do. (AS110731D), coll. 31. VII. 2011, madecoc. 1. VIII, em. 22–29. VIII. 2011; 1♀, same
locality, 31. VII. 2011, ovipositing (Fig. 1D), A.
Shinohara; 1♀, Nikko, Yumoto, 30. VII. 1986,
T. Saito. Kanagawa Pref. — 1♂, same data as
holotype, but made coc. 24. VII., em. 30. VIII.
2006; 1♂, do., but made coc. 24. VII., em. 13.
IX. 2006; 1♂, do., but made coc. 24. VII., em.
17. IX. 2006; 1♂, do., but made coc. 24. VII.,em. 19. IX. 2006; 1♀, do., but made coc. 24.
VII., em. 28. IX. 2006; 1♀, do., but made coc.
24. VII., em. 30. IX. 2006; 1♀, do., but madecoc. 25. VII., em. 24. IX. 2006; 1♂, do., but
made coc. 25. VII., em. 26. IX. 2006; 1♀, do.,but made coc. 25. VII., em. 27. IX. 2006; 1♀,
do., but made coc. 26. VII., em. 15. VIII. 2006;
3♀, do., but made coc. 27. VII., em. 28. IX.
2006; 1♀, do., but made coc. 28. VII., em. 7. IX.
2006; 1♂, do., but made coc. 28. VII., em. 9. IX.
2006; 1♀, do., but made coc. 28. VII., em. 11.
IX. 2006; 1♀, do., but made coc. 28. VII., em.
14. IX. 2006; 1♀, do., but made coc. 28. VII.,em. 17. IX. 2006; 2♂, Hakone, OwakudaniUbako, 17. VI. 2004, K. Kubo; 1♂, Hakone,
Ubako, 17. VI. 2004, K. Kubo; 1♀, Hakone,
Owakudani, 19. VIII. 2004, K. Kubo; 1♀,
Hakone, Komagatake, 21. VIII. 2002, H. Nagase.
Gunma Pref. — 1♀, Tsumakoi-mura, Kazawaonsen, 6. VIII. 2010, H. Kojima. Nagano Pref. —29

1♀, Takayama-mura, “Yamanokami”, 5. VIII.
2010, H. Kojima; 1♂, Utsukushigahara, 10.
VIII. 1976, Y. T. and H. Suda; 2♀, Tateshinayama, Tenshojihara, 29. VII. 1972, A. Shinohara;
1♂, Hara-mura, ca. 1300 m, from group of larvae (AS060728B), coll. 28. VII. 2006, made coc.
29. VII., em. 24. VIII. 2006, Host: Enkianthus
campanulatus, A. Shinohara; 1♂, do., but madecoc. 29. VII., em. 25. VIII. 2006; 1♀, do., but
made coc. 29. VII., em. 27. VIII. 2006; 1♀, do.,but made coc. 29. VII., em. 10. IX. 2006; 1♀,
do., but made coc. 30. VII., em. 18. VIII. 2006;
1♀, do., but made coc. 30. VII., em. 12. IX.
2006; 1♀, do., but made coc. 30. VII., em. 14.
IX. 2006; 1♀, do., but made coc. 30. VII., em.
18. IX. 2006; 2♀, do., but made coc. 2. VIII.,em. 28. IX. 2006; 1♀, do., but made coc. 3.
VIII., em. 30. IX. 2006; 2♀, Otaki, Mt. Ontakesan, 1600m, Nakanoyu, 21. VII. 1981, A. Shinohara. Shiga Pref. — 1♀, Otsu, “Mt. Hira”,
9. VIII. 1939, Takeuchi (Osaka Prefecture University, Sakai). Shikoku: Kochi Pref. — 1♂
“Prov. Tosa, H. Okamoto, Ishizuchi, 23. VII.
1935” (HU). Other material: 9 larvae, part of
HH060731A; 9 larvae, part of HH060731B; 4larvae, part of HH060802D; 4 larvae, part of
HH060802F, ﬁxed 6. VIII. 2006; 11 larvae, partof AS060722A; 1 larva, part of AS060728B,
ﬁxed 2. VIII. 2006.
Etymology. The speciﬁc epithet, enkianthus,
refers to the host plant and is a noun in apposition.
Host plant. Ericaceae: Enkianthus campanulatus (Miq.) G. Nicholson.
Field observations and rearing records. We
collected 26 groups of gregarious larvae in the
period from early July to early September, in
2006–2011 (Table 1). The groups found in theﬁeld consisted of one to 45, most frequently 10
to 30 larvae. In the group of HH060804A, somerows of remains of eggs were found along basal
margins of the neighboring leaves where larvae
were found (Fig. 1E). Shinohara observed afemale ovipositing into the basal margin of a leaf
(Fig. 1D). Larvae fed on leaves, leaving the mainveins and petioles (Fig. 1K). Larvae spun

Hara-mura, ca. 1300 m

AS060722A
AS060728B* Reared by Hara in Bibai (HH) or by Shinohara in Tokyo (AS).
** Other specimens died or ﬁxed in larval stage.

Owakudani, 1020 m, Hakone

NaganoAS100817A

Kirifuri, 1230 m, Nikko

Kanagawa

AS080706A
AS080706B
AS080706C
AS080706D
AS090712C
AS090802I
AS090813H
AS100905B
AS110731D
AS110909B
AS110909C
AS110909D
AS110909E

Hanaishi-cho, 640 m, Nikko

Naruko, 250–300 m, Osaki

Tochigi

HH060802F
HH060731A
HH060731B
HH060802B
HH060802C
HH060802D
HH060802E
HH060804A
HH060804B
HH060804C

Onikobe, 300 m, Osaki

Miyagi

Larval group
code*

Details

Locality

Summary of rearings.

Prefecture

Table 1.

10＋

30＋

2＋

10＋
6＋
4＋
3＋
several
3＋
7＋
1
8＋severalseveralseveral
1

15
45
2
20
19
22
26
5
19

16

Number oflarvae28.VII.2006

22.VII.2006

17.VIII.2010

6.VII.2008
6.VII.2008
6.VII.2008
6.VII.2008
12.VII.2009
2.VIII.2009
13.VIII.2009
5.IX.2010
31.VII.2011
9.IX.2011
9.IX.2011
9.IX.2011
9.IX.201131.VII.2006
31.VII.2006
2.VIII.2006
2.VIII.2006
2.VIII.2006
2.VIII.2006
4.VIII.2006
4.VIII.2006
4.VIII.2006

2.VIII.2006

Found

29.VII.–2.VIII

24–28.VII.

15.VIII.

13–14.VII.
9–11.VII.
7–9.VII.
8–10.VII.
29.VII.
12.VIII.
14.VIII.
7.IX.
1.VIII.
(dead before maturity)(dead before maturity)(dead before maturity)
9.IX.

9–10.VIII
5–7.VIII
5.VIII
6–8.VIII
6–8.VIII
9–10.VIII(dead before maturity)
6–7.VIII
9–16.VIII

912.VIII

Cocooned

18.VIII.–30.IX.2006 (8♀2♂)

15.VIII.–30.IX.2006 (13♀6♂)(dead in cocoons)

30–31.VII.2008 (9♀)(dead in cocoons)(dead in cocoons)(dead in cocoons)(dead in cocoons)(dead in cocoons)(dead in cocoons)(dead in cocoon)
22–29.VIII.2011 (8♀)———(dead in cocoon)

24.VIII.2006 (1♀2♂)
19–25.VIII.2006 (12♀5♂)(dead in cocoons)
22–27.VIII.2006 (4♀2♂)
22.VIII.–8.IX.2006 (9♀2♂)
26–27.VIII.2006 (2♀3♂)—
24.VIII.–2.IX.2006 (1♀)(dead in cocoons)24.VIII.–8.IX.2006 (5♀1♂)

Emerged (number and sex**)30
Hideho Hara and Akihiko Shinohara

Arge enkianthus n. sp. from Japancocoons within soil or paper in cages, andbecame adults within the same year. For the individuals in the groups AS060722A, AS060728B,
AS080706A, and AS110731D, the dates on
which larvae made cocoons and adults emerged
were recorded as detailed in the material examined. Cocoon periods were 20 to 68 (55.2 onaverage) days in females (n＝13) and 37 to 63(51.0) days in males (n＝6) in AS06722A, 19 to
59 (46.9) days in females (n＝8) and 26 to 27(26.5) day in males (n＝2) in AS060728B, 16 to
17 days in females (n＝9) in AS080706A, and 21
to 28 days in females (n＝8) in AS110731D.
Discussion
Comparison with the Related Species
Arge enkianthus is one of the blue-black species having hyaline wings with a black transverseband on the forewing and a basally pale hindtibia. It is distinguished from the similar looking
species by the long and sub-triangular sawsheath(Fig. 3A–C) and the apically narrow and basallyrounded valviceps with a basal lateral lobe (Fig.
5). A combination of the following features also
serve to recognize this species: Setae mostly
whitish; abdomen without pale areas; ﬂagellum
brown to black; hind coxa to femur black; hindtarsus brown to black, at most pale on bases of
one to three basal tarsomeres; wings with stigma
mostly black, veins dark except for C, Sc andapical section of R1 yellow and section of R1
basal to stigma often widely yellow; frontal area
medially concave throughout or posteriorly, withlateral ridge not or slightly raised anteriorly; interantennal carinae sharp, dorsal end curved medially and becoming low or separated from eachother, and ventrally fused into sharp supraclypeal
carina; male antenna narrow and not compressed,
2.0–2.1× head width; right mandible without
notch on inner margin; in both wings, wing margin between veins Rs and Cu scarcely or sparsely
ciliate, with marginal glabrous area narrower
than width of vein M and marginal setae slightly
longer than width of vein M; in female, seventh
sternum with posterior margin weakly roundly

31

produced at middle; lancet ventrally serrate only
basally, with apical annuli arched toward base oflancet; in male genitalia, gonostipes in ventral
view more or less narrowing apically, and harpe
in dorsal view narrow and pointed at apex.
In Takeuchiʼs (1939) key, this species runs to
A. jonasi (Kirby, 1882) described from Japan.
Arge jonasi is similar to A. kobayashii Takeuchi,
1931 and A. solowiyofka (Matsumura, 1911),
both from Japan and Sakhalin (Hara et al., 2007).
All three are larger species, usually more than
10 mm long in females and more than 8 mm longin males, and have a weakly carinate or rounded
median supraclypeal ridge and a robust sawsheath. For more characters of the three species,see Hara et al. (2007). In Gussakovskijʼs (1935)
key, this species runs to the couplets 145/162, butdoes not agree with either of them.
In immature stages, this species is easily distinguished from Japanese congeners by the hostplant and the unique coloration of the ﬁnal instar
larva.
Geographical Variation in Larval Coloration
The adults of this species show small variation
both in external and genitalic characters, but thelarvae vary rather greatly in color pattern and thisvariation is apparently related to geography. We
have examined larvae from four widely separated
areas, namely, Osaki (250–300m, Miyagi Prefecture, early to ﬁnal instars), Nikko (640–1230m,
Tochigi Prefecture, early to ﬁnal instars), Hakone(1020m, Kanagawa Prefecture, semiﬁnal andﬁnal instars) and Hara-mura (1300m, Nagano
Prefecture, semiﬁnal and ﬁnal instars). As
described above, most conspicuous difference isin the head coloration of the early to semiﬁnal
larvae, which is mostly black in the northernmost
Osaki population (Fig. 1F, G) and entirely
creamy to yellow in other three populations
located in more southwestern areas (Fig. 1I, L).
The ﬁnal instar larvae also exhibit some differences among the populations as detailed above.
The signiﬁcance of these apparent regional variations is still unknown. The stability of these characters in each local population and distribution of

32

Hideho Hara and Akihiko Shinohara

these variations within the entire range of thespecies should be examined with more material
in the future.
Host Plant
Larvae of argid sawﬂies feed on plants of various families, including the Ericaceae. In Japan,
two species, Arge similis (Snellen van Vollenhoven, 1860) and Spinarge afﬁnis Hara and Shinohara, 2006, are known to feed on Rhododendron (Shinohara and Hara, 2010) and one
species, Spinarge pumila Hara and Shinohara,
2006, is known to feed on Elliottia (Shinohara
and Hara, 2011). In North America, two speciesof Arge, A. abdominalis Leach, 1817, and A. azaleae Smith, 1989, are associated with Rhododendron (Smith, 1989). These are probably the only
available records of the association of argid sawﬂies with Ericaceae. Arge enkianthus is the ﬁrst
argid sawﬂy known to feed on Enkianthus, andthis is the ﬁrst record of Enkianthus as a hostplant of sawﬂies.
Life History
The ﬁeld collection dates of the adults (11females and six males) are roughly divided into
two periods; three males in middle June, and 11
females and three males from late July to lateAugust. We collected larvae in the ﬁeld fromearly July to early September (Table 1). These
became adults from late July to late September inthe same year and the cocoon periods greatly
varied from 16 to 68 days. Based on our observations, the life history of this species may be summarized as follows: Adults occur from late spring
to early autumn; the female lays her eggs in a
row along basal margins of adjacent leaves (Fig.
1D, E); the larvae gregariously feed on leaves,leaving the main veins and petioles (Fig. 1K); themature larva enters the soil and spins a cocoon.
The sawﬂy probably has two or more generations
a year and the adult emergence is probably polymodal, which is a rather common feature in multivoltine species of the genus (Shinohara andHara, 2008, 2009; Shinohara et al., 2009).

Acknowledgements
We thank T. Hirowatari (Osaka Prefecture
University, Sakai), H. Kojima (Nagano), K.
Kubo (Yokohama), H. Nagase (Kamakura), M.
Ohara (Hokkaido University, Sapporo), T. Saito(Nikko), N. Shinohara (Tokyo) and H. Suda
(Sakura) for making the material available forthis study, and David R. Smith (United States
Department of Agriculture, Washington, D.C.)
for his careful review of the manuscript.
References
Gussakovskij, V. V., 1935. Chalastogastra (pt. 1). Faune
de l ʼURSS (n. s. 1), Insectes Hyménoptères, II (1).
XVIII＋453 pp. Édition de lʼAcademie des Sciences delʼURSS, Moscou, Leningrad. (In Russian with Germansummary.)Hara, H., H. Kojima and A. Shinohara, 2007. Arge solowiyofka (Hymenoptera, Argidae) feeding on Betula
ermanii, newly recorded from Japan. Japanese Journalof Systematic Entomology, 13: 85–89.
Shinohara, A. and H. Hara, 2008. Taxonomy, distribution
and life history of Abelia-feeding sawﬂy, Arge suzukii(Hymenoptera, Argidae). Japanese Journal of Systematic Entomology, 14: 29–47.
Shinohara, A. and H. Hara, 2009. Arge indicura n. sp.
feeding on Potentilla and Sanguisorba from Japan(Insecta, Hymenoptera, Argidae). Bulletin of the
National Museum of Nature and Science, Series A, 35:
55–71.
Shinohara, A. and H. Hara, 2010. Host plants, larvae andlife history of Spinarge afﬁnis and S. fulvicornis(Hymenoptera, Argidae) in Japan. Japanese Journal of
Systematic Entomology, 16: 47–62.
Shinohara, A. and H. Hara, 2011. Host plant, larva andlife history of Spinarge pumila (Hymenoptera, Argidae)
in Japan. Bulletin of the National Museum of Natureand Science, Series A, 37: 203–208.
Shinohara, A., H. Hara and J.-W. Kim, 2009. The speciesgroup of Arge captiva (Insecta, Hymenoptera, Argidae). Bulletin of the National Museum of Nature andScience, Series A, 35: 249–278.
Smith, D. R., 1989. The sawﬂy genus Arge (Hymenoptera: Argidae) in the Western Hemisphere. Transactionsof the American Entomological Society, Philadelphia,
115: 83–205.
Takeuchi, K., 1939. A systematic study on the suborder
Symphyta (Hymenoptera) of the Japanese Empire (II).
Tenthredo, Kyoto, 2: 393–439.