Bull. Natn. Sci. Mus., Tokyo, Ser. A, 30(2), pp. 87–103, June 22, 2004

The Myrmecophilous Hoverfly Genus Microdon(Diptera, Syrphidae, Microdontinae) in Hokkaidô, Japan,
with Descriptions of Four New Species
Teruhiko Hironaga1 and Munetoshi Maruyama2
1

Systematic Entomology, Graduate School of Agriculture, Hokkaidô University, Sapporo-shi, 060–8589 Japane-mail teruhiro@res.agr.hokudai.ac.jp
2
Department of Zoology, National Science Museum, 3–23–1 Hyakunin-chô,Shinjuku-ku, Tokyo, 169–0073 Japane-mail maruyama@kahaku.go.jp

Abstract Six species, including four new species, of the myrmecophilous hoverfly genus Microdon (Syrphidae, Microdontinae) are recognised in Hokkaidô, Japan. They are: M. macrocerus
sp. nov., M. kidai sp. nov., M. yokohamai sp. nov., M. murayamai sp. nov., Microdon bifasciatus
Matsumura, 1916, and M. simplex Shiraki, 1930 (new to Hokkaidô). Larva and puparium of M.
kidai are described. The following symbiotic hosts are clarified: M. macrocerus—Camponotus(Camponotus) obscuripes; Microdon kidai and M. yokohamai—Formica japonica (fusca group);
M. murayamai—F. lemani (fusca group). Microdon japonicus and M. auricomus are formerly
recorded from Hokkaidô, but as those records are as highly doubtful that the two species could be
excluded from the fauna of Hokkaidô. Key to the species of Microdon in Hokkaidô, including M.
japonicus and M. auricomus, is appended for accurate identification.
Key words : Symbiotic host, key to species, larva, puparium, Hymenoptera, Formicidae, Formica, Camponotus.

Introduction
About 20 species of the myrmecophilous hoverfly genus Microdon Meigen, 1803, have been
known in the Palearctic region. The Japanesefauna of the genus has been still poorly investigated. Recently several unknown species havebeen discovered from Japan one after another(Katsura, 1996a, b; Ohishi, 2002a, b), though
they are mostly unidentified or undescribed. Only
two species, M. japonicus Yano, 1915, and M. bifasciatus Matsumura, 1916, were recorded till
lately (Ogata, 1989), but some additional species
were currently reported also from Hokkaidô; Kumata et al. (1994) recorded M. auricomus Coquillett, 1898, from Akan-chô, and Yokohama(1996 a, b) reported two species from Sapporoshi, which were tentatively identified with M. latifrons Loew, 1856, and M. aff. maritimus Vi-

olovitsh, 1976.
As a result of field surveys made by our colleagues and by the authors themselves in Japanand investigation of syrphid collections depositedin Hokkaidô University, about a hundred specimens of Microdon hoverflies were available fortaxonomic studies. Of these, specimens from
Hokkaidô are classified into six species, of whichfour are found to be new to science.
All the species of Microdon are considered tobe myrmecophiles living in ant nests in their immature stages, but symbiotic host is unknown for
most Japanese species. Some of the specimens
examined were collected around ant nests, andsymbiotic hosts of some species were clarified.
In the present paper, we are going to review
the Microdon species of Hokkaidô with several
new information.

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Teruhiko Hironaga and Munetoshi Maruyama

Materials and Methods
The terminology used in the present study follows McAlpine (1981). Taxonomy of Microdon
is usually very difficult and shape of male genitalia is not so informative in some cases. In thepresent paper, identification of species is mainly
based on the external morphology, in particular,ratio in length of antennal segments, presence orabsence of apical spines on scutellum, colorationof abdominal hairs, and ratio of width and lengthof tarsomeres.
The male terminalia were macerated in 10%
KOH solution heated in an incubator (60°C), forfive to more than 24 hours on occasion, and thentransferred into ethanol and distilled water forwashing, after dissected in the glycerol, observed
and figured under a microscope.
Holotypes and some paratypes are deposited in
the laboratory of Systematic Entomology,
Hokkaidô University (SEHU) and the National
Science Museum, Tokyo (NSMT).
Taxonomy
Microdon macrocerus sp. nov.
[Japanese name: Higenaga-arinosuabu](Figs. 1–8, 39)“Microdon latifrons”: Yokohama, 1996a: 9.
Microdon sp.: Yokohama & Chiba, 1998: 7.

Type series. Holotype: male, Kamimuri (Ikoino-mori), Maruseppu-chô, Hokkaidô, 3 VII
2003, Y. Kida (NSMT). Paratypes: [Hokkaidô]: 2males, 2 females, same data as holotype; 1 male,same locality and collector as holotype, 1 VII
2000; 1 male, ditto, 11 VI 2003; 1 male, ditto, 13
VI 2003; 1 male, Ishiyama, Sapporo-shi, 22 VI
1916, S. Matsumura (labelled “Microdon micans
Wied.”) (SEHU); 1 male, Hyakumatsuzawa, Mimami-ku, Sapporo-shi, 26 V–1 VI. 1998, K. Mizota, T. Hironaga, A. Ohkawa & M. Maruyama(by a Malaise trap); 3 females, same locality, collectors and collecting method, 9–16 VI 1998; 1
male, 1 female, Misumai, Minami-ku, Sapporoshi, 16 VI 1991, M. Yokohama; 1 female, Soranuma-dake, 2 VII 1961, S. Takagi (SEHU); 2

males, Apoi-dake, Samani-chô, 22 VI 1959, S.
Uéda (SEHU); 1 male, Nukabira, Kamishihorochô, 13 VII 1959, T. Kumata (SEHU); [Honshu]:
6 males, 1 female, Torikura-yama (alt. 1780 m),
Ôshika-mura, Nagano-ken, 21 VI 2003, K.
Katsura; 1 male, Ôkubo-shitsugen, Shirakawamura, Gifu-ken, 2 VI 2002, K. Harusawa.
Distribution. Japan: Hokkaidô, Honshû.
Symbiotic host. Camponotus (Camponotus)
obscuripes Mayr, 1879.
Etymology. Denoting the long antennae.
Diagnosis. This species is similar to Microdon
japonicus, but easily distinguished from the latterby the 1st flagellomere more than three times aslong as pedicel. This species could be determined by the keys of Mutin & Barkalov (1999)
and Violovitsh (1983) as “M. latifrons Loew,
1856” (M. miki Doczcal et Schmid, 1999) or
M. ignotus Violovitsh, 1976, but is distinguishedfrom “M. latifrons” by the coloration of the legs
and the shape of the 2nd tarsomere of hind leg
which is usually less than twice as long as width,and distinguished from M. ignotus by the face
below the antennal base without broad bare part.
Description. Male (Fig. 1). Body length: 11.5–
12.2 mm; wing length: 8.2–9.1 mm.
Coloration: Body mostly black. Head blackwith aeneous lustre; antennae black, slightly
brownish; arista dark brown. Thorax black;mesonotum with aeneous shimmer; pleura shining aeneous black but its posterior part brownish.
Abdomen black with slight aeneous lustre. Legs
black, with tibiae, tarsi and extreme tip of femora
brown; tibiae with ill-defined narrow blackish
ring after middle; tarsi sometimes darkened.
Wings hyaline, slightly brownish; around veins
blackish tinged; veins dark brown; squamae yellowish white; halteres yellowish.
Head wider than mesonotum, about 1.9–2.1
times as wide as long or 1.5–1.7 times as high as
long; frons 0.24–0.27 times as wide as head at
the narrowest part, and clothed with yellowish
hairs which become black at middle; vertex
clothed with yellow hairs; face 0.53–0.54 times
as wide as head at middle level, slightly broadened ventrally, and clothed with light yellow

Microdon in HokkaidôFigs. 1, 2.

89

Facies of Microdon macrocerus sp. nov.; 1, male; 2, female.

hairs; occiput clothed with pale yellow hairs
which become whitish below; genae very small,and clothed with brownish grey pubescence.
Eyes about 1.8 times as high as long in profile
and almost glabrous. Antennae (Figs. 3, 4) withscape as long as or slightly shorter than 1st flagellomere; 1st flagellomere more than threetimes as long as pedicel; arista shorter than 1st
flagellomere and about 0.7 times of its length;
ratio of scape, pedicel and 1st flagellomere:—3.3–3.8 : 1 : 3.4–3.9.
Thorax: Scutum clothed with pale yellow
hairs; scutellum slightly shorter than half width,with posterior margin more or less excavated andbearing two very tiny spines, and clothed withlong pale-yellow hairs; anepimeron and upper

part of anepisternum clothed with long pale-yellow hairs; katepisternum clothed with pale yellow hairs on dorsal part and a few hairs mesally.
Abdomen (Fig. 5) oval, about 1.3 times as longas wide, distinctly broader than thorax at 2nd and3rd tergites, somewhat longer than head and thorax combined, and clothed mainly with pale yellow hairs; 3rd tergite clothed with short black
hairs in anterior half, pale hairs at posterior margin faded medially; 4th tergite similarly clothedwith black and yellow hairs as in 3rd tergite, andclothed with pale yellow hairs on posterior third,
which extended onto anterior part as a V-shape,
while all side margins are clothed with similar
pale yellow hairs; sternites clothed with long
pale-yellow hairs; 4th sternite with posterior mar-

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Teruhiko Hironaga and Munetoshi Maruyama

Coloration: Abdomen with 5th tergite and sternite black.
Head with frons 0.39–0.42 times as wide ashead, gradually broadened forwards, and clothedwith black hairs which become pale yellow atsides of anterior half; face 0.51–0.52 times aswide as head at middle level. Antennae withscape longer than 1st flagellomere; ratio of scape,pedicel and 1st flagellomere:—3.7–4.3 : 1 : 3.2–
3.9.
Abdomen (Fig. 6) with 5th tergite clothed withshort black hairs which become pale yellow toanterolateral corners and posterior apex; 4th and5th sternites clothed with short orange yellow
hairs.
Biology. Y. Kida (pers. comm.) observed several adults flying near the nest of Camponotus
obscuripes in Kamimuri, Maruseppu-chô. Somewere emerged from the entrance to the nest.
Microdon kidai sp. nov.
Figs. 3–8. Microdon macrocerus sp. nov. —— 3,
Left antenna, dorsal view; 4, ditto, lateralview; 5, abdomen, dorsal view, male (black
areas indicate patterns of black hairs); 6, ditto,
female; 7, cercus, lateral view; 8, surstylus,
lateral view.

gin truncate; terminalia clothed with very shortyellowish hairs; cerci rather broad (Fig. 7);
surstyli (Fig. 8) rather short, with a notch, whichcannot be seen laterally.
Legs clothed with rather short yellowish hairs;
ventral side of each tarsus clothed with orange
hairs; fore tarsus with 1st tarsomere about 2.1–
2.3 times as long as wide and with 2nd tarsomere
longer than wide, 1.3–1.5 times as long as wide;
hind tarsus with 1st tarsomere 2.8–3.1 times aslong as wide and about as long as the following
three segments combined, and with 2nd tarsomere 1.8–2.0 times as long as wide.
Wings about three times as long as wide andabout 1.5 times as long as head and thorax combined; squamae with pale fringes.
Female (Fig. 2). Similar to male. Body length:11.8–12.5 mm; wing length: 10.3–10.8 mm.

[Japanese name: Shinonome-arinosuabu](Figs. 9–22, 39)

Type series. Holotype: male, Shinreisui,
Maruseppu-chô, Hokkaidô, 12–13 VI 2001, M.
Maruyama & K. Uesugi (near nests of F. japonica) (SEHU). Paratypes: [Hokkaidô]: 12 males, 3
females, same data as holotype; 1 male, same locality, 21 V 2000, coll. pupa, 2 VI 2000,
emerged, Y. Kida, (from a nest of Formica japonica). 1 male, 3 females, ditto, 8 VI 2001. Y. Kida;
1 female, Kamimuri, Maruseppu-chô, 22 V 2001,
coll. pupa, 31 V 2001, emerged, M. Maruyama(from a nest of Formica japonica).
Other material. One larva and 2 pupae, samedata as holotype.
Distribution. Japan: Hokkaidô.
Symbiotic host. Formica japonica Motschulsky, 1866.
Etymology. Dedicated to Mr. Yasunari Kida
for his invaluable contribution to the ant andmyrmecophile fauna in Hokkaidô.
Diagnosis. This species could be identified by
the keys of Mutin & Barkalov (1999) and Violovitsh (1983) with M. maritimus Violovitsh,

Microdon in Hokkaidô91

Figs. 9, 10. Microdon kidai sp. nov., facies; 9, male; 10, female.

1976, described from the Russian Far East, but
distinguished from it by the legs entirely blackand the shape of male cerci and surstyli. This
new species also resembles M. oitanus Shiraki,
1930, known from Japan, but differs from it by
the face broader (in M. oitanus, 0.40–0.43 times
as wide as head) and the 3rd abdominal tergite
with black hairs anteriorly.
Description. Male (Fig. 9). Body length: 13.0–
13.5 mm; wing length: 10.1–11.0 mm.
Coloration: Body mostly black. Head blackwith bluish lustre; vertex with some purplish lustre; antennae black; arista brown. Thorax withmesonotum shining bluish black; pleura black;anepisternum, anepimeron and katepisternum
with bluish lustre. Abdomen black; 2nd and 3rd
tergites with aeneous lustre, sternites black withbluish to greenish reflection, terminalia blackwith a slight bluish tinge. Legs black; apical segment of each tarsus slightly brownish. Wings
hyaline, but more or less brownish toward baseand anterior margin, and usually veins emphasized in black; veins dark brown, but rather yellowish on basal part of wing; squamae yellowish
white but its margins yellow; halteres pale yellow, but brownish at stem.
Head about as wide as mesonotum, about half
as long as wide and nearly 1.5 times as high as
long; frons about 0.18 times as wide as head at
the narrowest part, and densely clothed with erect
black hairs leaving extreme apex and transverse
groove, which become pale yellow on eye margins and posterior part of transverse groove; vertex clothed with black hairs which become yel-

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Teruhiko Hironaga and Munetoshi Maruyama

low at posterior part; face 0.47–0.48 times aswide as head, subparallel-sided, and clothed withlong pale-yellow hairs; occiput clothed with paleyellow hairs; genae clothed with grayish pubescence. Eyes about 1.8 times as high as long in
profile, and sparsely clothed with minute hairs.
Antennae (Figs. 11, 12) with scape slightly shorter than two apical segments combined; pedicel
about one-third as long as scape; 1st flagellomere
about twice as long as pedicel; arista about 0.8
times as long as 1st flagellomere; ratio of scape,pedicel and 1st flagellomere:—2.5–2.6 : 1 : 2.
Thorax: Scutum densely clothed with light orange hairs, which becomes pale yellow laterally;
scutellum rather semicircular, about half as longas wide, with posterior margin moderately excavated medially, bearing two distinct short spines,
and densely clothed with long pale-yellow hairs;
anepimeron and upper part of anepisternum partly with long pale-yellow hairs; katepisternum
clothed with pale yellow hairs dorsally and a few
hairs on ventromedial margin.
Abdomen (Fig. 13) oval, moderately narrowed
behind, strongly broader than thorax at 2nd and3rd tergites, almost as long as head and thorax
combined, about 1.2 times as long as wide, andclothed with pale yellow hairs; anterior twothirds of 3rd tergite and anterior half of 4th tergite clothed with short black hairs; sternites
rather sparsely clothed with pale yellow hairs;posterior margin of 4th sternite roundly notched
medially; terminalia clothed with short yellow
hairs, cerci subtriangular (Fig. 15); surstyli (Fig.
16) very long and deeply notched at middle.
Legs clothed with pale hairs, many black hairs
being mixed on dorsal surface of femora; tarsi
clothed with black hairs on dorsal surfaces andwith yellow hairs on ventral side; fore tarsus with
1st tarsomere about 1.5 times as long as wide,
and with 2nd tarsomere shorter than wide, about
0.9 times as long as wide; hind tarsus with 1sttarsomere about 2.5 times as long as wide andabout as long as the following three segments
combined, and with 2nd tarsomere about 1.4
times as long as wide.
Wings about three times as long as wide, about

Figs. 11–16. Microdon kidai sp. nov. —— 11,
Left antenna, dorsal view; 12, ditto, lateralview; 13, abdomen, dorsal view, male (black
areas indicate patterns of black hairs); 14,ditto, female; 15, cercus, lateral view; 16,
surstylus, lateral view.

1.6 times as long as head and thorax combined,
and distinctly shorter than thorax and abdomen
combined; squamae with yellowish fringes.
Female (Fig. 10). Quite similar to male. Body
length: 13.0–13.9 mm; wing length: 10.8–11.0mm.
Coloration: Frons with greenish shimmer. Abdomen with 5th tergite shining black; 5th sternite
shining black with some greenish reflection.
Head with frons 0.38–0.41 times as wide ashead, broadened forwards, evenly clothed withblack hairs except eye margins.
Abdomen (Fig. 14) with 5th tergite clothedwith pale yellow hairs which become black in anterior margin; 5th sternite clothed with pale yellow hairs.
Larva (inster unknown) (Fig. 17). Length: 8.0–
8.1 mm; width: 6.5–6.5 mm. Yellowish white inground colour; posterior spiracular tubercle dark-

Microdon in Hokkaidô93

Figs. 17–19. Microdon kidai sp. nov., immature stages —— 17, larvae, dorsal view; 18, pupa, dorsal view; 19,ditto, dorsolateral view.

er. Surface moderately covered with reticulations,which comprise small projections and become
clearer laterad. Posterior spiracular tubercle finely granulate punctured but irregularly rugose
around tip. Lateral margin densely ciliated.
Puparium (Figs. 18, 19). Length: 9.8–10.2 mm;
width: 7.5–7.9 mm. Reddish brown in groundcolour; anterior spiracular tubercles and theirbasal area brown; posterior spiracular tubercle
darker. Surface moderately covered with reticulations, which comprise small projections and become clearer laterad. Anterior spiracular tubercles papilliform, rugose around tips, verticallywrinkled around base. Posterior spiracular tubercle almost unilobed but slightly bifid at apex;
surface finely granulate punctured but irregularly

rugose around spiracular openings, in which
margins slightly produced. Dorsal fringe very
short and weakly ciliated. Ventral fringe penicilliated.
Biology. Maruyama observed behaviour of theadults (Figs. 20–22) and the presence of the larvae and pupae on 12–13, June, 2001 at Shinreisui, Maruseppu-chô. Several adults flying or
resting on stones around the colonies of Formica
japonica were observed. Then, several pairs weremating near the entrance of the nest, and in manycases, the females were in just after eclosion andnot well stained. In contrast most males were
well stained and seemed to have been emergedsome days before. Probably male emerges earlier
than female and wait for eclosion of female near

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Teruhiko Hironaga and Munetoshi Maruyama

Figs. 20–22. Microdon kidai sp. nov., living indivuduals —— 20, Female resting on a stone, just after eclosion;
21, mating, posterodorsal view; 22, ditto, lateral view. (Photographed by Hiroshi Sugaya.)the hosts’ nest.
Under stones where F. japonica nested, several
larvae and pupae of the hoverfly were observed.
The larvae were all in the same size, so that it
seems probable that two years are needed for thisspecies to become adult from egg.

Microdon yokohamai sp. nov.
[Japanese name: Nishiki-arinosuabu](Figs. 23–30, 39)“Microdon aff. martimus”: Yokohama, 1996 b.

Type series. Holotype: male, Takinosawa-rindô(near Sapporo-ko), Minami-ku, Sapporo-shi,
Hokkaidô, 5 VII 2000, T. Hironaga (near a nestof Formica japonica) (SEHU). Paratypes:[Hokkaidô]: 1 male, 9 females, same data as
holotype; 1 male, same locality, 7 VII 2001, M.
Takashima; 1 female, Pankenai-gawa, Utanoborichô, 28 VI 1999, T. Hironaga; 1 male, Uryû[probably, Uryû-chô], 5 VII 1935, Okada; 1 female, Tenninkyô (alt. 1000 m), Asahi-dake, Bieichô, 20 VII 2001, O. Tominaga; 3 males, 2 females, Yukomabetsu (alt. 1100 m), Asahi-dake,
Higashikawa-chô, 22 VII 2001, K. Katsura; 2males, Moiwa-yama, Minami-ku, Sapporo-shi,
15 VI 1991, M. Yokohama; 1 female, Kannonzawa, Minami-ku, Sapporo-shi, 26 VI 2002, T.
Yoshida; 3 females, Hyakumatsuzawa, Minamiku, Sapporo-shi, 23–30 VI 1998, K. Mizota, T.
Hironaga, A. Ohkawa & M. Maruyama (by aMicrodon in Hokkaidô95

Figs. 23, 24. Microdon yokohamai sp. nov., facies; 23, male; 24, female.

Malaise trap); 4 females, Muine-yama, Minamiku, Sapporo-shi, 4 VII 1998, M. Ôhara & K.
Sugisima.
Distribution. Japan: Hokkaidô.
Symbiotic host. Formica japonica.
Etymology. Dedicated to Mr. Mitsuhiro Yokohama, who first reported the presence of thisspecies in Hokkaidô, for his contribution to theclarification of the syrphid fauna of Hokkaidô.
Diagnosis. This species could be determinedby using the key by Mutin & Barkalov (1999)
and Violovitsh (1983) as M. maritimus describedfrom the Russian Far East, but is distinguishedfrom the latter in the legs entirely black and theshape of male surstyli, which have a deep notchat the middle. This new species is also similar to
M. kidai, and M. oitanus, but distinguished fromthe former in having narrower face: 0.41–0.43
times as wide as head width (0.47–0.48 times in
M. kidai); the 3rd abdominal tergite without
black hairs anteriorly; and the 4th abdominal
sternite with black hairs medially, and from thelater by having broader frons (about 0.15 times
as wide as head in M. oitanus [male]).
Description. Male (Fig. 23). Body length:12.5–13.9 mm; wing length: 10.1–11.2 mm.
Coloration: Body mostly black. Head black;frons deep black with bluish lustre; face blackwith bluish lustre; occiput black with bluish or
greenish shimmer; antennae black; arista darkbrown. Thorax almost black; mesonotum shining
greenish black; pleura blackish; anepisternum,
anepimeron and katepisternum shining bluishblack. Abdomen shining greenish black; 4th ter-

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Teruhiko Hironaga and Munetoshi Maruyama

gite deep black with less greenish shimmer; terminalia black. Legs almost all black. Wings hyaline, around the veins emphasized in black; veinsdark brown, rather yellowish on basal part ofwing; squamae yellowish; halteres orange yellow.
Head about as wide as mesonotum, about half
as long as wide and about 1.6 times as high as
long; frons about 0.2 times as wide as head at thenarrowest part, and clothed with erect black hairsleaving transverse groove and becoming golden
yellow to posterior part of vertex; face 0.41–0.43
times as wide as head, subparallel-sided, andclothed with light yellow hairs; occiput clothedwith short black hairs and rather long yellow
hairs, and with pale yellow hairs in lower half;
genae clothed with brownish gray pubescence.
Eyes about 1.9 times as high as long in profileand very sparsely covered with minute hairs. Antennae (Figs. 25, 26) with scape as long as orvery slightly shorter than two apical segments
combined; pedicel about one-third as long as
scape; 1st flagellomere twice as long as pedicel
and about three-fourths or two-thirds as long as
scape; arista slightly shorter than 1st flagellomere; ratio of scape, pedicel and 1st flagellomere:—2.6–3 : 1 : 2.
Thorax: Scutum densely clothed with rather
long orange yellow hairs; scutellum rather semicircular, about twice as wide as long, with posterior margin slightly excavated medially, bearing
two very short spines, densely clothed with erectorange-yellow hairs; anepimeron and upper partof anepisternum clothed with pale yellow hairs;
katepisternum clothed with pale yellow hairs on
dorsal and ventromedial margins, and with a few
hairs mesally.
Abdomen (Fig. 27) oval, longer than head andthorax combined, strongly broader than thorax,
about 1.4 times as long as wide, moderately narrowed behind, and clothed with pale yellow hairs;
4th tergite clothed with short black hairs in anterior half; sternites rather sparsely clothed withpale yellow hairs; 4th sternite slightly concave inposterior margin, clothed with yellow hairs
which become black medially; terminalia clothedwith short black hairs; cerci subtriangular (Fig.

Figs. 25–30. Microdon yokohamai sp. nov. ——25, Left antenna, dorsal view; 26, ditto, lateralview; 27, abdomen, dorsal view, male (black
areas indicate patterns of black hairs); 28,ditto, female; 29, cercus, lateral view; 30,
surstylus, lateral view.

29); surstyli very long and deeply notched at
middle (Fig. 30).
Legs: femora clothed with black hairs, butwith some pale yellow hairs in basal fourth ofposterior surface; tibiae clothed with pale yellow
hairs, and sometimes intermixed with sub-depressed black hairs on anterior surface; tarsi
clothed with black hairs dorsally and orange yellow hairs ventrally; fore tarsus with 1st tarsomere
1.3–1.4 times as long as wide, and with 2nd tarsomere shorter than wide, 0.7–0.9 times as longas wide; hind tarsus with 1st tarsomere 2.3–2.4
times as long as wide and about as long as thefollowing three segments combined, and with
2nd tarsomere 1.1–1.4 times as long as wide.
Wings about 2.8 times as long as wide, 1.5–
1.6 times as long as head and thorax combined,
and distinctly shorter than thorax and abdomenMicrodon in Hokkaidô

combined; squamae with yellowish fringes.
Female (Fig. 24). Quite similar to male. Body
length: 12.1–15.5 mm; wing length: 9.8–11.4mm.
Coloration: Abdomen with 5th tergite shining
black; 5th sternite shining black with somegreenish reflection.
Head with frons 0.39–0.41 times as wide ashead, broadened forwards, and evenly clothedwith black hairs.
Abdomen (Fig. 28) with 5th tergite clothedwith yellow hairs, which becomes blackish along
anterior margin; 4th and 5th sternites entirely
clothed with black hairs.
Biology. Behaviour of adults observed by theauthors was almost the same as that of M. kidai.
Microdon murayamai sp. nov.
[Japanese name: Komachi-arinosuabu](Figs. 31–38, 39)

Type series. Holotype: male, Hokkaidô University Tomakomai Experimental Forest (alt. 30–55 m), Takaoka, Tomakomai-shi, Hokkaidô, 16
VI 2002, S. Murayama (near a nest of Formica
lemani) (SEHU). Paratypes: [Hokkaidô]: 1 male,
1 female, same data as holotype; 1 female, same
locality, 30 VI 2002, M. Maruyama (near a nestof F. lemani); 1 female, same locality, 3 VII
2003, T. Hironaga; 1 male, Futatsuyama (Kayanuma), Shibecha-chô, 28 VI 2001, K. Ijima; 3males, 1 female, Shiriuchi-chô, 21 VI 1976, T.
Kumata (SEHU); 1 male, Fukushima-chô, 20 VI
1976, T. Kumata (SEHU); [Honshû]: 1 male,
Hayachine-san (alt. 600 1000 m), Iwate-ken, 1112 VII 1980, M. Suwa (SEHU); 4 males, 2 females, Kawairi, Yamato-chô, Fukushima-ken, 14
VI 1998, M. Maruyama.
Distribution. Japan: Hokkaidô, Honshû.
Symbiotic host. Formica lemani Bondroit,
1917.
Etymology. Dedicated to Mr. Shigeki Murayama, a collector of the type series.
Diagnosis. This new species could be determined as M. lehri Mutin, 1999 by using a key of
the Syrphidae in the Russian Far East (Mutin &97

Barkalov, 1999), which is the original descriptionof this species. Though the description lacks extensive description and figure of this species, thepresent new species can be distinguished fromM. lehri in the following character states: palehairs dominated on the vertex; the 3rd abdominal
tergite with a large black patch of hairs medially;
the 5th abdominal tergite without black hairs infemale. This species is quite similar to M. auricomus, but differs from the latter in the 3rd and4th abdominal tergites always clothed with black
hairs. This new species is also similar to M. devius (Linnaeus, 1761) but distinguished from it inhaving black hairs dorsally on each tarsus, scutellum without distinct spines, and black haired partof 4th tergite divided medially.
Description. Male (Fig. 31). Body length:11.2–11.5 mm; wing length: 8.7–9.2 mm.
Coloration: Body mostly black. Head blackwith aeneous shimmer; frons shining deep black;face shining aeneous black; occiput black withaeneous lustre; antennae black with base andventral side of scape brownish; arista brown.
Thorax black; mesonotum with bluish lustre;
anepisternum, anepimeron and katepisternum
with shining bluish to aeneous lustre. Abdomen
black to blackish brown with dull greenish lustre;terminalia black with some bluish reflection.
Legs dark reddish brown, but the following parts
blackish: basal halves of anterior femora, midand hind femora except ventral surface of apicalthird, apical thirds of anterior and mid tibiae,
hind tibiae and basal two segments of hind tarsi.
Wings hyaline, slightly infuscated around veins;
veins blackish brown, but rather yellowish on anterior part of wing; squamae whitish but its margins yellowish; halteres yellowish.
Head slightly wider than mesonotum, slightly
shorter than half of width and 1.6–1.8 times ashigh as long; frons 0.16–0.17 as wide as head at
the narrowest part, and clothed with black hairs,posterior part to vertex clothed with black andpale yellow hairs; face 0.42–0.43 times as wide
as head, subparallel-sided, and clothed with paleyellow hairs; occiput clothed with pale hairs;
genae very small, clothed with grayish pubes-

98Teruhiko Hironaga and Munetoshi Maruyama

Figs. 31, 32. Microdon murayamai sp. nov., facies; 31, male; 32, female.

cence. Eyes about 1.9 times as high as long in
profile, almost glabrous, but very sparsely withminute hairs. Antennae (Figs. 33, 34) with scapeslightly shorter than the following segments combined; pedicel shorter than half of scape; 1st flagellomere twice as long as pedicel; arista shorter
than 1st flagellomere; ratio of scape, pedicel and1st flagellomere:—2.4 : 1 : 2.
Thorax: Scutum clothed with pale yellow erecthairs, which are substituted by black hairs medially; scutellum rather semicircular, about half as
long as wide, with posterior margin moderately
excavated medially, but without spines, anddensely clothed with long orange hairs;
anepimeron and upper part of anepisternum
rather sparsely clothed with long pale-yellow
hairs; dorsal part of katepisternum clothed withpale yellow hairs and a few hairs on ventromedial
margin.
Abdomen (Fig. 35) oval, strongly broader thanthorax, about as long as head and thorax combined, about 1.2 times as long as wide, anddensely clothed with yellow hairs on dorsum,
which become[s] longer and paler to each lateral
margin and very short and black at middle of 3rd
and 4th tergites; sternites rather sparsely clothedwith pale yellow hairs, 4th sternite very shallowly notched medially on posterior margin; terminalia clothed with short pale hairs; cerci subtriangular (Fig. 37); surstyli (Fig. 38) long andnotched at middle.
Legs: femora and tibiae clothed with pale yellow hairs, black hairs mainly on dorsal surface(some specimens lacking black hairs on tibiae);

Microdon in Hokkaidô99

which become black forwards; ocellar tubercle
clothed with black hairs.
Abdomen (Fig. 36) with 5th abdominal tergite
clothed with yellow hairs which become paler onlateral parts; 5th sternite clothed with pale yellow
hairs.
Biology. S. Murayama (pers. comm.) observed
the adults stopping or flying near the entrance ofnests of F. lemani in Tomakomai.
Microdon bifasciatus Matsumura, 1916
[Japanese name: Futaobi-arinosuabu](Fig. 39)
Microdon bifasciatus Matsumura, 1916: 254; Shiraki,
1930: 15; Matsumura, 1931: 346; Shiraki, 1950: 1647;
Shiraki & Edashige, 1953: 124; Edashige, 1965: 208;
Shiraki, 1968: 9; Peck, 1988: 227; Ogata, 1989: 795;
Ohishi, 2002a: 202.

Figs. 33–38. Microdon murayamai sp. nov. ——33, Left antenna, dorsal view; 34, ditto, lateralview; 35, abdomen, dorsal view, male (black
areas indicate patterns of black hairs); 36,ditto, female; 37, cercus, lateral view; 38,
surstylus, lateral view.

tarsi clothed with black hairs on dorsal part andwith yellow hairs on ventral surface; fore tarsus
with 1st tarsomere about 1.7 times as long as
wide, and with 2nd tarsomere shorter than wide,
about 0.9 times as long as wide; hind tarsus with
1st tarsomere about 2.8 times as long as wide andabout as long as the following three segments
combined, and with 2nd tarsomere about 1.5
times as long as wide.
Wings about 2.8 times as long as wide andabout 1.5 times as long as head and thorax combined; squamae with yellowish fringes.
Female (Fig. 32). Quite similar to male, but
abdomen rather broad. Body length: 10.8–12.4mm; wing length: 8.9–9.5 mm.
Coloration almost the same as in male.
Head with frons about 0.37–0.40 times aswide as head, and clothed with pale yellow hairs

Type material. Holotype: female, Jôzankei,
Sapporo, Hokkaidô, 11 VII 1912, S. Matsumura(SEHU).
Additional records. [Hokkaidô]: 1 male,
Okushiri-tô, 14 VII 1958, K. Kamijo; 1 female,Uryû [probably, Uryû-chô], 21 VII 1964, K.
Kusigemati; 1 female, Nupinai-gawa, Taiki-chô,
11 VII 2000, T. Hironaga; 1 male, Kikonai-chô, 9VIII 1976, T. Kumata et al.
Distribution. Japan: Hokkaidô, Honshû,Shikoku.
Symbiotic host. Unknown.
Remarks. This species is quite distinct among
Japanese species of Microdon in the elongate abdomen. Though several similar species are
known in the adjacent regions of the distribution,e.g., “Microdon sp.” from Nansei Islands(Ohishi, 2002a) and a species erroneously
recorded as “M. bifasciatus” from South Korea(Han & Choi, 2001), M. bifasciatus is easily distinguishable from them in having the entirely
black legs.
Microdon simplex Shiraki, 1930
[Japanese name: Hime-ruriiro-arinosuabu](Fig. 39)

100

Teruhiko Hironaga and Munetoshi Maruyama

Fig. 39. Collection sites of Microdon spp. —— M. macrocerus (closed stars), M. kidai (closed circles), M.
yokohamai (closed squares), M. murayamai (closed triangles), M. bifasciatus (open stars), M. simplex (opencircles).
Microdon caeruleus var. simplex Shiraki, 1930: 9; Shiraki& Edashige, 1953: 124.
Microdon caeruleus Brunetti, 1908: 92; Shiraki, 1932: 55,
1950: 1647; Edashige, 1965: 208.
Microdon simplex: Shiraki, 1968: 12; Ohishi, 2002a: 204.
Microdon caeruleus simplex: Peck, 1988: 227; Ogata,
1989, 795; Han & Choi, 2001: 187.

Type material. Not examined.
Additional records. [Hokkaidô]: 1 male, 1 female, Botanic Garden, Hokkaidô University,Chûô-ku, Sapporo-shi, 22 VII 2003, T. Hironaga;
1 male, Hyakumatsuzawa, Minami-ku, Sapporoshi, 25 VI 1999, T. Hironaga.
Distribution. Japan: Hokkaidô, Honshû,Shikoku, Kyûshû, Tsushima; Korea; Taiwan.
Symbiotic host. Unknown.
Remarks. This species has not been well described after the original description and its taxonomic placement is unstable, i.e., sometimes regarded as a subspecies of M. caeruleus Brunetti,
1908, or a distinct species. However, this species

is easily distinguished from M. caeruleus by thefollowing character states: the scutellum without
apical spines, the mid and hind femora black inbasal halves, and each tibia paler in the basal
half. Therefore, M. simplex is regarded as a distinct species in the present study.
This species is newly recorded from
Hokkaidô.
Doubtful Records from Hokkaidô
Microdon auricomus Coquillett, 1898
[Japanese name: Kin-arinosuabu]
Microdon auricomus Coquillett, 1898: 320; Yano, 1915:
8; Shiraki, 1930: 21; Matsumura, 1931: 346; Shiraki,
1932: 56; Shiraki, 1950: 1647; Shiraki, 1968: 5; Peck,
1988: 227; Han & Choi, 2001: 185; Ohishi, 2002a:
201.
Microdon auricomus var. nigripes Shiraki, 1930: 22.
Microdon auricomus nigripes: Peck, 1988: 227; Ogata,
1989: 795; Kumata et al., 1994: 1131.

Distribution. Japan: Honshû, Kyûshû; Korea.

Microdon in Hokkaidô

Symbiotic host. Formica japonica.
Remarks. Kumata et al. (1994) recorded thespecies from Hyôtan-numa, Akan-chô in eastern
Hokkaidô. However, we were unable to examine
any specimen of this species collected from
Hokkaidô inspite of our careful searches of thehost nests. This species is similar to some othermembers of the genus distributed in Hokkaidô,especially M. murayamai in general appearance.
The above record may be based on misidentification of M. murayamai.

japonicus is normally very common in its distributional range in Honshû. In spite of our investigation of this species, including search for its larvae in the nests of L. japonicus, in the fields in
Hokkaidô, we have been unable to find it. Thus,
the distribution of M. japonicus over Hokkaidô ishighly doubtful.

1.

Microdon japonicus Yano, 1915
[Japanese name: Arinosuabu]–

Microdon japonicus Yano, 1915: 1; Shiraki, 1930: 20;
Matsumura, 1931: 347; Shiraki, 1950: 1648; Edashige,
1965: 208; Shiraki, 1968: 3; Peck, 1988: 228; Ogata,
1989: 795; Ohishi, 2002a: 203.
Microdon jezoensis Matsumura, 1916: 255 (synonymized
by Shiraki, 1930: 20).

2.

Distribution. Japan: Honshû, Shikoku,Kyûshû.
Remarks. Matsumura (1916) described Microdon jezoensis from Sapporo in Hokkaidô, but
Shiraki (1930) synonymized it with M.
japonicus. This caused the record of M. japonicus in Hokkaidô. The arrangement by Shiraki(1930) was not based on examination of the typesof both the species but only on the original descriptions. Matsumura’s (1916) description islacking details and illustration of body parts,
which are indispensable for identification of thetaxonomically difficult group. Although the illustration of the facies given by Matsumura (1916)
is obscure, it is apparently different from those of
M. japonicus in the antennal shape, which issomewhat similar to that of M. macrocerus.
Therefore, adequacy of Shiraki’s (1930) arrangement is highly doubtful. Examination of the typeof M. jezoensis is needed for clarifying the matter, but we were unable to find it in the SEHU
collection, where the most part of Matsumura’s
collection should be deposited. It is probably
missing. Microdon japonicus is known to be associated with Lasius japonicus Santschi, 1941,
and the larvae inhabiting the nest of the ant. M.

101

–
3.
–
4.
–
5.
–
6.

–

7.

–

Key to the Known Species of Microdonin Hokkaidô
Body small, less than 10 mm. Second abdominal sternite divided by median membranous part. . . . . . . . . . . . . . . . . . . . M. simplex
Body medium-sized to large, more than 10mm. Second sternite not divided by median
membranous part . . . . . . . . . . . . . . . . . . . . . 2
Abdomen conical, slender, more than 1.6
times longer than wide . . . . . . M. bifasciatus
Abdomen ovate, broad, less than 1.5 times
longer than wide . . . . . . . . . . . . . . . . . . . . . 3First flagellomere about three times as longas pedicel . . . . . . . . . . . . . . . . M. macrocerus
First flagellomere about twice as long as
pedicel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Scutum usually clothed with dark brown to
black hairs . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Scutum without black hairs . . . . . . . . . . . . . 7
Scutellum with a pair of spines . . . . . . . . . . .
. . . . . . . . . . . M. japonicus (record doubtful)
Scutellum without spines . . . . . . . . . . . . . . 6
Third and 4th abdominal tergites with distinct large patches of black hairs . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . M. murayamai
Third and 4th abdominal tergites usually
without black hairs, rarely with a pair ofrather small patches of black hairs anteriorly. . . . . . . . . . M. auricomus (record doubtful)
Third abdominal tergite sparsely covered
with pale yellow hairs, densely covered withblack hairs anteriorly . . . . . . . . . . . . M. kidai
Third abdominal tergite almost uniformly
and densely covered with pale yellow hairs,
without black hairs anteriorly . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . M. yokohamai

102

Teruhiko Hironaga and Munetoshi Maruyama

Acknowledgements
We thank Mr. Keitaro Harusawa (Ôsaka-sayama-shi), Mr. Kazuo Ijima (Shibecha-chô), Mr.
Kohjiro Katsura (Ôsaka-shi), Mr. Y. Kida
(Maruseppu Insectarium), Mr. Kôji Mizota(Miyagi University of Education), Mr. S. Murayama (Low Temperature Science, Hokkaidô University), Dr. Masahiro Ôhara (Hokkaidô University Museum), Ms. Ayuko Ohkawa (Furano-shi),
Mr. Kazuhiro Sugisima (SEHU), Ms. Masaki
Takashima (Sapporo-shi), Mr. Osamu Tominaga(Nada-shi), Mr. Kenta Uesugi and Mr. Takuma
Yoshida (SEHU) for material. Thanks are also
due to Mr. M. Yokohama (Sapporo-shi) for helpful information and Mr. H. Sugaya (SEHU) forthe photographs of the living indivuduals of M.
kidai. T. H. thanks the staff of Botanic Garden,
Hokkaidô University, for assistance and permitting him collecting in the garden. Last but notleast, we thank Dr. Shun-Ichi Uéno for reading
manuscript and valuable comments.
This study is supported in part by a 21st Century Centre of Excellence (COE) Program on“Neo-Science of Natural History” (Program
Leader: Hisatake Okada) at Hokkaidô University
financed by the Ministry of Education, Culture,
Sports, Science and Technology, Japan to T. H.,
and by a grant from Research Fellowship of theJapan Society for the Promotion of Science for
Young Scientists (Postdoctoral Fellow) to M. M.
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