Content uploaded by Zoltan Korsos
Author content
All content in this area was uploaded by Zoltan Korsos on May 31, 2014
Content may be subject to copyright.
Accepted by W. Shear: 21 Apr. 2011; published: 13 May 2011
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2011 · Magnolia Press
Zootaxa 2877: 55–68 (2011)
www.mapress.com/zootaxa/Article
55
Two new millipede species of the genus Riukiaria (Diplopoda, Polydesmida,
Xystodesmidae) endemic to the Ryukyu Archipelago, Japan
ZOLTÁN KORSÓS1,2,4, YASUYUKI NAKAMURA2 & TSUTOMU TANABE3
1Department of Zoology, Hungarian Natural History Museum, Baross u. 13, H-1088 Budapest, Hungary. E-mail: korsos@nhmus.hu
2Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
3Faculty of Education, Kumamoto University, Kurokami, Kumamoto 860-8555, Japan
4Corresponding author
Abstract
We describe two new species of the millipede genus Riukiaria from two islands of the Ryukyu Archipelago: R. maculata
sp. n. from Tane-ga-shima, northern Ryukyus, and R. mundyi sp. n. from Yonaguni-jima, the southwesternmost member
of the Yaeyama Island Group. Both species show the simple forceps-like male gonopod structure typical for the genus,
but they are readily distinguishable from other members by their unique color patterns. We have also compiled a list of
species in the genus described up to now.
Key words: species description, Tane-ga-shima, Yonaguni-jima
Introduction
The millipede genus name Riukiaria was invalidly proposed (without type species) by Verhoeff (1936), but two
years later Attems (1938) designated R. pugionifera Verhoeff, 1936 as its type species, and hence became the
author of the genus. Several species were described subsequently under the names Rhysodesmus and Rhysolus
(Gressitt 1941; Takakuwa 1941, 1942; Miyosi 1952a, 1952b, 1957; Wang 1956, 1957; Haga 1968; Golovatch
1978) until Shinohara (1977) finally established that all East Asian species of „Rhysodesmus” should be referred to
Riukiaria Attems, 1938 (with a junior synonym of Rhysolus Chamberlin and Wang, 1953) or Takakuwaia Verhoeff,
1936 (which became a junior synonym of Xystodesmus Cook, 1895, according to Hoffman 1956). The genus Rhy-
sodesmus Cook, 1895 hence became appropriately restricted to the North American species (Hoffman 1980).
The genus Riukiaria is classified in the tribe Xystodesmini with four related East Asian genera: Koreoaria Ver-
hoeff, 1937; Levizonus Attems, 1898; Xystodesmus Cook, 1895; and Yaetakaria Hoffman, 1949. Tanabe and Shino-
hara (1996) synonymized Harpaphini with Xystodesmini, hence pooling the North American genera Harpaphe
Cook, 1904, Isaphe Cook, 1904, Thrinaphe Shelley, 1993, and Tubaphe Causey, 1954 into Xystodesmini as well.
Hoffman (1999) did not consider Xystodesmini, and maintained Harpaphini for Harpaphe and Isaphe, whereas
removed Tubaphe into Chonaphini.
Hoffman (1980, p. 187) diagnosed Harpaphini according to gonopodal structure, and this diagnosis was
accepted and transferred to Xystodesmini by Tanabe and Shinohara (1996, p. 1470): “male gonopod with long,
nearly straight sternal apodeme and telopodite generally reduced in size, equaling coxae or appreciably smaller in
overall bulk”. They also suggested a close relationship between Riukiaria and Xystodesmus, saying (Tanabe and
Shinohara 1996, p. 1479) that “the two genera share three unique character states: (1) gonocoxae have one mac-
roseta; (2) posterolateral corners of paranota are rounded on segments 1-4 and acutely produced on segments 5-18;
(3) metatergites have rows of tubercles. … These possible synapomorphies suggest that the two genera are closely
related to each other.” However, with our new direct observations, characters 2 and 3 seem questionable, and put
the separation of the two genera on different grounds (e.g. body size, body coloration, and gonopod conformation
details). On a recent molecular tree based on mitochondrial COI-COII sequences and using maximum likelihood
KORSÓS ET AL.
56 · Zootaxa 2877 © 2011 Magnolia Press
analysis (Sota & Tanabe 2010), selected species of Riukiaria and Xystodesmus (as outgroup to Parafontaria) came
together as sister groups.
It is not the purpose of the present paper to evaluate the status of Riukiaria and Xystodesmus as opposed to each
other, but the finds (one older and one recent) of two new species from two different islands of the Ryukyu Archi-
pelago make formalizing the species content of the genus Riukiuaria long overdue. Below, we give a list of the spe-
cies presently assigned to Riukiaria, with their type localities.
List of Riukiaria species
1. Riukiaria anachoreta Tanabe, 1988—Japan, Kyushu, Kagoshima Prefecture, Kagoshima City, Yoshida
2. Riukiaria bifida (Takakuwa, 1942)—Japan, Ryukyus, Kagoshima Prefecture, Amami-O-shima Island
3. Riukiaria capaca Wang and Zhang, 1993—China, Fujian Prov., Jangle County
4. Riukiaria chelifera (Takakuwa, 1941)—Japan, Ryukyus, Okinawa Prefecture, Ishigaki-jima Island
5. Riukiaria chinensis Tanabe, Ishii and Yin, 1996—China, Zhejiang Prov., Tian-mu Mts.
6. Riukiaria cohaesiva (Wang, 1957)—Taiwan, Taipei County, "Urai" (= Wulai)
7. Riukiaria contigua (Wang, 1957)—Taiwan, Taipei County, "Urai" (= Wulai)
8. Riukiaria cornuta (Haga, 1968)—Japan, Kyushu, Kumamoto Prefecture, Kuma District, Mt. Gongen-yama
9. Riukiaria datei (Miyosi, 1957)—Japan, Shikoku, Ehime Prefecture, Minamiuwa District, Ka-shima Island
10. Riukiaria diacantha (Miyosi, 1952)—Japan, Shikoku, Ehime Prefecture, Kitauwa District, Aizi (=Kihoku
Town)
11. Riukiaria falcifera Verhoeff, 1936—Japan, Ryukyus, Okinawa Prefecture, Okinawa-jima Island
12. Riukiaria geniculata (Takakuwa, 1941)—Japan, Kyushu, „Nagasaki”
13. Riukiaria holstii (Pocock, 1895)—Japan, Ryukyus, Okinawa Prefecture, Okinawa-jima Island
14. Riukiaria jamila Tanabe, 1990—Japan, Ryukyus, Kagoshima Prefecture, Yaku-shima Island
15. Riukiaria marinae (Golovatch, 1978)—Japan, Kyushu, Nagasaki Prefecture, Unzen City, Obama
16. Riukiaria montana (Haga, 1968)—Japan, Kyushu, Fukuoka Prefecture, Kitakyushu City, Mt. Sarakura-san
17. Riukiaria ochracea (Gressitt, 1941)—Taiwan, „Sozan”
18. Riukiaria puella Tanabe, 1988—Japan, Ryukyus, Kagoshima Prefecture, Yaku-shima Island
19. Riukiaria pugionifera Verhoeff, 1936—Japan, Ryukyus, Okinawa prefecture, Okinawa-jima Island
20. Riukiaria rosulans (Tömösváry, 1885)—Japan, Kyushu, „Nangasaki”
21. Riukiaria scutata (Takakuwa, 1942)—Japan, Ryukyus, Kagoshima Prefecture, Amami-O-shima Island
22. Riukiaria semicircularis (Takakuwa, 1941)—In the original description the type locality was not specifically
designated. However, in the list of localities given there Kagoshima [City] is the first, then followed by Hon-
shu (north to Ishikawa Prefecture) of Japan, and Busan of South Korea.
Riukiaria semicircularis hosidei (Miyosi, 1952)—Japan, Honshu, Yamaguchi Prefecture, Hagi City, Kasa-
yama
23. Riukiaria spiralipes (Takakuwa, 1942)—Japan, Ryukyus, Okinawa Prefecture, Kume-jima Island
24. Riukiaria taiwana (Takakuwa, 1942)—Taiwan, Taichung County, Taichung
25. Riukiaria uncata (Haga, 1968)—Japan, Honshu, Yamaguchi Prefecture, Mine District, Shibuki
26. Riukiaria uraensis (Wang, 1956)—Taiwan, Taipei County, "Urai" (= Wulai)
In addition to the 26 nominal species and one subspecies above (some of them may turn out to be synonyms of
each other), the following two species can probably also be assigned to Riukiaria: “Pachydesmus” attemsi Wang,
1960 (Taiwan, Yan Ming Shan), and Sinoria tianmu Tanabe, Ishii and Yin, 1996 (China, Zhejiang Prov., Tian-mu
Mts.). Here we present the descriptions of two new species, both from the Ryukyu Archipelago which gave its
name to the entire genus (Verhoeff 1936).
Zootaxa 2877 © 2011 Magnolia Press · 57
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
Material and methods
In the present paper the Ryukyu Archipelago is understood in its biogeographical sense (see Hikida & Ota 1997;
Motokawa 2000; Nakamura & Korsós 2010). We follow the definition as including all the islands along the
Ryukyu Arc between Kyushu and Taiwan, comprising six island groups from northeast to southwest, the Osumi,
Tokara, Amami, Okinawa, Miyako, and Yaeyama Groups. Two major geological barriers, the Tokara and the
Kerama Gaps, respectively, divide the islands into three regions: the Northern (Osumi Group and northern part of
Tokara Group), Central (southern part of Tokara Group, Amami and Okinawa Groups), and Southern (Miyako and
Yaeama Groups) Ryukyus. This definition is somewhat different from the political, administrative units: the
Osumi, Tokara, and Amami Groups belong in Kagoshima Prefecture, whereas all others (Okinawa, Miyako and
Yaeyama Groups) constitute Okinawa Prefecture. Together, they are also often called ’Nansei shoto’ (”Southwest-
ern Islands”) in Japanese.
Specimens were collected by the first (ZK) and second (YN) authors on four trips to the islands in the frame-
work of a comprehensive survey to investigate the millipede fauna of the Ryukyu Archipelago. Type materials are
deposited in the Department of Zoology, Division of Terrestrial Invertebrates, National Museum of Nature and Sci-
ence, Tokyo (NSMT), in the University Museum (Fujukan) of the University of the Ryukyus, Okinawa (RUMF),
and in the Myriapoda Collection of the Hungarian Natural History Museum, Budapest (HNHM).
Specimens were observed and drawn by the first author (ZK) with a Leica M125 stereomicroscope in the Trop-
ical Biosphere Research Center, the University of the Ryukyus. Measurements are based on all available speci-
mens, midbody paranotal width is given as that of the 10th segment. Terminology of the male gonopods (Fig. 1)
follows Tanabe and Shinohara (1996), with advice from R. L. Hoffman, W. A. Shear, and R. M. Shelley (in litt.).
Live photographs were taken in the field by ZK with a Nikon D90 digital camera, fitted with 60 mm Micro Nikkor
macro lens and R1C1 macroflash system. For UV illumination, a Toshiba FL20S Black Light Blue (20 W) lamp
was used.
FIGURE 1. Schematic Riukiaria gonopod, right, mesal view. Abbreviations: cm= coxal macroseta, ca= coxal apophysis, pf=
prefemur, pfp= prefemoral process, ps= prostatic groove, s= solenomere. Prefemur (with prefemoral process) + acropodite
(with prostatic groove running along solenomere) = telopodite.
KORSÓS ET AL.
58 · Zootaxa 2877 © 2011 Magnolia Press
Taxonomy
Riukiaria maculata sp. n.
Figs 2–3, 7–13.
Holotype male (NSMT-My 377)—Japan, Northern Ryukyus, Osumi Group, Tane-ga-shima Island, Nakatane
Town, Cryptomeria mixed forest close to the airport, 260 m alt., N30.6401° E130.9797°, 7 July 2010, leg. R. & Z.
Korsós.
Paratypes: 3 females, 3 juvs (NSMT-My 378, HNHM)—Same locality and date.
3 females (RUMF)—Japan, Northern Ryukyus, Osumi Group, Tane-ga-shima Island, Nakatane Town, Cryp-
tomeria forest close to the airport, 260 m alt., N30.6401° E130.9797°, 12 October 2009, leg. Z. Korsós & Y. Naka-
mura.
Diagnosis. A species of the genus Riukiaria as defined by Shinohara (1977) and Tanabe and Shinohara (1996)
with the simple, forceps-like male gonopod conformation. It differs from all congeners by its coloration (a pair of
distinct dark, brownish-black patches on each segment, including collum), by its exclusive occurrence on a single
island (Tane-ga-shima), and in details of gonopod morphology: a small but definite triangular process ventrally on
coxa (Figs 10-11, tp), and by shape and length of both prefemoral process and acropodite.
Etymology. Named after the color pattern, unusual in the genus (adjective, feminin).
Description. Measurements: Medium sized species in comparison to other members of the genus. Length of
holotype male 40 mm, midbody paranotal width 7.5 mm, metatergal length 1.9 mm, collum width 6.2 mm, length
2.7 mm. Adult female body length 40–43 mm, midbody paranotal width 7.7–8.5 mm, metatergal length 1.8–2.2
mm, collum width 6.4–6.7 mm, length 2.9–3 mm (n= 3).
Color in life (Fig. 2): Same coloration in both sexes, prozona, metazona with yellow background, metaterga
laterally with a pair of distinct, oval, brownish-black patches, occupying about 1/4th of total paranotal width on
both sides. Paranota yellow with slightly darker, orange margins. Head dark greyish-brown, antennae, legs, and
underside pale yellow or whitish. Collum with broad yellow anterior and lateral margins, the two dark spots closer
to each other than on following metaterga. Last segment with epiproct uniformly yellow. Dark patches also distinct
in UV light (Fig. 3), their fluorescence much less intense. Preserved specimens (70% ethanol) after 10 months still
have the typical pattern, although the patches are somewhat faded. Juvenile specimens (with body length of ca. 15
mm) uniformly greyish-yellow, and do not show the characteristic spots.
Head smooth, epicranial suture distinct, 2+2 frontal setae, 1+1 between antennal sockets, 1+1 above clypeus,
and 2 dense rows at its margin and on labrum. Antennae straight, first article globose, 2nd about twice as long as
first, articles 3–6 subequal in length, slightly longer than 2nd, 7th smallest, shorter than wide. Anterior part of gna-
thochilarial stipites and lamellae linguales densely hairy, mentum with a distinct, median hair-field.
Collum convex, smooth, shiny, lateral and posterior margins with very weak ridge, lateral corners triangular,
pointed caudad. Pro- and metaterga (Fig. 7) smooth without traces of tubercles or punctuation, but from 5th
onwards with definite posterior marginal ridge. Posteriolateral edge of paranota 2–3 triangular, of 4th and onwards
pointed caudad. Pores on paranota 5,7,9,10,12,13,15,16,17, and 18, in median depression in lateral view. Body
sides between segments 5-16 parallel, segments 17–19 strongly tapering, posteriolateral projections becoming
more pointed. Epiproct in dorsal view triangular, its straight shape only broken by 3+3 lateral and 1+1 apical knobs
(Fig. 8), in lateral view protruding over paraprocts (anal valves), parallel-sided, straight. Setation: 1+1 anterio-lat-
erally on knobs, 4+4 medially on lateral sides, 2 of them on knobs, and 2+2 apically, not on knobs. Paraprocts mar-
ginate with 2+2 setae, one pair marginally, the other pair posteriorly on sides of paraprocts, hypoproct wide
subtrapezoid, with 1+1 setae on knobs.
Midbody legs well separated, in male closer to each other (1.8 mm), in females separated by 2.4–2.5 mm,
sterna smooth. Postgonopodal legs (in both sexes) with well-developed ventral spine on prefemur, increasingly
stronger towards body end, coxa and prefemur subequal in length, femur long and slender, slightly clavate, about
2.5x as long as prefemur, postfemur and tibia subequal in length, postfemur thicker, tibia more slender, its length
about 1/3rd of femur, tarsus even more slender, about 1.5x as long as tibia, claw (ca. 0.5 mm long) slightly curved.
Sexual characters: Coxa of 2nd legpair (Fig. 9) of holotype male with well-developed median projections
about half as long as length of coxa, apically rounded without membraneous tubulae, with several short setae, 2+2
macrosetae sitting proximally from j oint of prefemur (1 anteriorly, 1 posteriorly), and 1+1 small ones on lateral
Zootaxa 2877 © 2011 Magnolia Press · 59
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
FIGURES 2–3. Riukiaria maculata sp. n., holotype male. 2= Live coloration, Tane-ga-shima; 3= Live specimen in UV-light.
FIGURES 4–6. Riukiaria mundyi sp. n., paratype specimens. 4= Live coloration, Yonaguni-jima; 5–6 = The same specimens
in ambient flashlight, and in UV-light.
KORSÓS ET AL.
60 · Zootaxa 2877 © 2011 Magnolia Press
FIGURES 7–9. Riukiaria maculata sp. n. holotype male. 7= Anterior body part, dorsal view; 8= Epiproct and 19th segment,
dorsal view; 9= Sternum, coxa, and prefemur of 2nd legpair, posterior view. Scales 1 mm (7,8), 0.5 mm (9).
sides of coxa. Sternum on segment 4 (legpair 3) narrow, without lobes, on segment 5 (legpairs 4–5) and 6 (legpairs
6–7) gradually wider and smoother, bridging the 1.8 mm intercoxal distance on postgonopodal legs. No other ster-
nal or leg modifications could be observed. Male gonopodal aperture on 7th segment wide, elliptical, about twice
as wide as long, gonopods in situ usually deeply embedded, with acropodites crossing each other. Coxa (Figs 10–
11, c) stout, approximately as long as wide, without proximal apophysis but with small apophyseal macroseta (cm),
and distally (ventrally) with small but definite, triangular projection (tp). Cannula normal, situated on mesal side.
Telopodite has two simple processes (Figs 10–12), a shorter, more slender prefemoral process (pfp), and a long,
Zootaxa 2877 © 2011 Magnolia Press · 61
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
curved, leaflike acropodite (solenomere, s), delimitation of which from the densely setose prefemur is hardly visi-
ble. The two processes form the the simple, forceps-like gonopodal apparatus typical for Riukiaria (Tanabe & Shi-
nohara 1996). Prefemoral process slender, triangular (Fig. 12, pfp), about 3/4th of length of acropodite, with no
setae, hairs, or processes. Tip of acropodite (Fig. 12, s) bending backwards toward prefemoral process, almost
touching it, its sides gradually tapering, prostatic groove running along mesal side, and ending on the pointed tip.
FIGURES 10–13. Riukiaria maculata sp. n. 10–12 = Left gonopod of holotype male, lateral, mesal, and apical (ventral) views,
respectively; 13= Left cyphopod of paratype female, posterior view. Scales 0.5 mm. c= coxa, tp= triangular process, v= valve,
r= receptacle, op= operculum, other abbreviations as in Fig. 1.
KORSÓS ET AL.
62 · Zootaxa 2877 © 2011 Magnolia Press
Female cyphopods (Fig. 13) embedded closely behind 2nd legpair, in large, -shaped aperture, valves (v) sub-
rectangular, almost twice as wide as high, densely setose, with basal bumps of each seta giving a rough appearance
to its surface and margins. Lateral operculum (op) large, thick, almost as high as valves, with dense setation, recep-
tacles (r) embracing valves both anteriorly and posteriorly, subrectangular, with several series of short hairs along
ventral, serrated-like margin.
Distribution. Known only from Tane-ga-shima Island, northern Ryukyus (Osumi Island Group), Kagoshima
Prefecture, Japan. Specimens were found in the single locality of a mixed forest of deciduous trees, possibly an old
Cryptomeria japonica plantation. Search in other similar habitats on the island (about 445 square kilometers of
total surface area) produced no more specimens.
Remarks. Tane-ga-shima island, the locality of the new species’ population, is a member of the Osumi
Islands, Northern Ryukyus, about 50 km southeast of Kyushu. It is an elongate island 57 km from north to south,
and about 5–12 km from east to west, with the highest elevation 282 m. The nearest island is the small, uninhabited
Mage-jima, with an area of only 8 km2, and with no worth-while habitat for native millipedes. Yaku-shima island,
on the other hand, the largest member of the Osumi Group, is about 30 km to the west, and has a notable vegetation
and fauna. Its high mountains (up to 1936 m a.s.l.) are mainly covered by ancient Japanese cedar (Cryptomeria
japonica) forest, and provide an optimal habitat for many endemics. Two Riukiaria species have been described
from Yaku-shima (R. puella and R. jamila), but they both differ considerably in size (32–36 mm) and coloration
from R. maculata sp. n.: R. puella is almost entirely yellow, whereas tergites of R. jamila are gray with yellowish
white paranota. (For gonopod differences see Diagnosis.)
In the southern part of Kyushu, one of the four main islands of Japan, three Riukiaria species are known to
occur: R. cornuta, R. anachoreta, and R. semicircularis. Whereas their size is similar (R. anachoreta, body length
39–45 mm, R. semicircularis 40 mm) to, or larger (R. cornuta, 55 mm) than R. maculata sp. n., all three have a
generally greenish or brownish gray color, with a little yellow or whitish tint on the paranota in R. cornuta and R.
semicircularis. Moreover, metatergites of R. anachoreta show 3 transverse rows of conspicuous tubercles. Male
gonopods also differ in the length and shape of the acropodite and prefemoral process, the former in case of R. cor-
nuta bearing a small mesal tooth. The prefemoral process of R. semicircularis is long and slender, undulated like a
flagellum, and only a little shorter than the acropodite, the tip of which bends backwards to form an almost com-
pletely closed oval.
Based only on superficially similar coloration, we also might to compare R. maculata sp. n. with R. falcifera
from Okinawa-jima island. The two locations are more than 500 km apart by sea, and R. falcifera is considerably
larger (53–65 mm), but its coloration also differs from the new species, the dark spots never being so strong, and
not of the same size. In R. maculata, the spots are always widely separated by the yellow median part, and all are
the same size on each segment, giving really a 'spotted' appearance to the animal. In R. falcifera, on the other hand,
the spots are blurred, sometimes missing or fused together, and change in their size and shape along the body of the
animal.
Since R. maculata sp. n. is only known from a single population, and because its attractive, colorful appear-
ance we recommend the new species for full legal protection. The new species could well be one of the rarest
Riukiaria species in Japan.
Riukiaria mundyi sp. n.
Figs 4–6, 14–19.
Holotype male (NSMT-My 379)—Japan, Southern Ryukyus, Yaeyama Group, Yonaguni-jima Island, Mt. Dunan-
dake, primary forest, N24.4577° E122.9711°, 146 m alt., 31 August 2009, leg. Z. Korsós & Y. Nakamura.
Paratypes: 3 males, 5 females, 2 juvs. (RUMF, HNHM)—Same locality and date.
1 male, 1 female (RUMF)—Japan, Southern Ryukyus, Yaeyama Group, Yonaguni-jima Island, Adigara Cave
area, near construction place, N24.4599° E122.9594°, 44 m alt., 2 September 2009, leg. Z. Korsós & Y. Nakamura
2 females (NSMT-My 380)—Japan, Southern Ryukyus, Yaeyama Group, Yonaguni-jima Island, Arakawabana
forest trail, 134 m, primary forest, N24.4441° E123.0107°, 1 September 2009, leg. Z. Korsós & Y. Nakamura
4 males, 5 females, 3 juvs. (RUMF, HNHM)—Japan, Southern Ryukyus, Yaeyama Group, Yonaguni-jima
Island, Kubura-bari, N24°27.4’ E122°56.6’, 50 m alt., rocky grassland, 14 February 2010, leg. R. & Z. Korsós
Zootaxa 2877 © 2011 Magnolia Press · 63
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
Diagnosis. A member of the genus Riukiaria as defined by Shinohara (1977) and Tanabe and Shinohara (1996)
with the simple, forceps-like male gonopod conformation. It differs from congeners first of all by its coloration in
life (almost uniformly pinkish-orange), by its exclusive occurrence on a single island (Yonaguni-jima), and in
details of gonopod morphology.
FIGURES 14–16. Riukiaria mundyi sp. n. 14= Anterior body part paratype male, dorsal view; 15= Epiproct of paratype male,
dorsal view; 16= Sternum, coxa, and prefemur of 2nd legpair of paratype male, posterior view. Scales 1 mm (14,15) and 0.5 mm
(16).
KORSÓS ET AL.
64 · Zootaxa 2877 © 2011 Magnolia Press
FIGURES 17–19. Riukiaria mundyi sp. n. 17–19= Left gonopod of paratype male, lateral and mesal views; 19= Left cyphopod
of paratype female, posterior view. Scale 0.5 mm. ms= macroseta, other abbreviations as in Figs 1, and 10–13.
Etymology. The specific epithet is a patronym in honor of Mr. Imre Mundy (Budapest), a Hungarian engineer,
long time friend and supporter of the first author (genitive, masculine).
Description. Measurements: Body size generally smaller than in most other Riukiaria species. Length of
males 36–42 mm, midbody paranotal width 7.5–8 mm, metatergal length 1.8–2 mm, collum width 6–6.6 mm,
length 2.4–3 mm (n= 4). Female body length 36–41 mm, midbody paranotal width 7.8–8.6 mm, metatergal length
1.8–2 mm, collum width 6.3–7.1 mm, length 2.8–3.3 mm (n= 8). Kubura-bari population (see Remarks): Male
body length 25–26 mm, midbody paranotal width 5.1–5.3 mm, metatergal length 1.2–1.3 mm, collum width 4.4–
4.6 mm, length 1.9–2.1 mm (n= 4). Female body length 30–31 mm, midbody paranotal width 6.3–6.8 mm, metater-
gal length 1.3–1.4 mm, collum width 5.2–5.5 mm, length 2.5–2.6 mm (n= 5).
Color in life (Fig. 4): Whole body is almost uniformly light orange, pinkish, occasionally tending toward red-
dish or dark yellowish. Head, prozona, legs, and underside paler, 6th segment of antennae, tibiae and tarsi whitish.
Zootaxa 2877 © 2011 Magnolia Press · 65
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
On collum and each metatergum a slightly darker, almost brownish median patch, pronounced towards paranota as
oval spots. On preserved specimens (70% ethanol) the vivid color quickly disappears, only shadows of the above-
mentioned pattern remains. Coloration of males and females does not differ. Fluorescence in UV light strong (Figs
5–6), especially on prozona and underside, metazona are slightly greyish.
Head smooth, epicranial suture distinct, 2+2 frontal setae, several setae scattered above clypeus, with 2 dense
rows at its margin and on labrum. Antennae straight, first article globose, 2nd slightly clavate, subequal with arti-
cles 3–5, 6th longest, about 1.2 x longer than 5th, 7th small, slender, slightly longer than wide. Gnathochilarial stip-
ites and lamellae linguales covered densely with short hairs, large, triangular mentum with smaller, distinct, median
hair-field.
Collum convex, smooth, shiny, lateral and posterior margin with weak ridge, lateral corners triangular, slightly
directed caudad. Pro- and metaterga smooth without any traces of tubercles or punctuation, not even wrinkles. Pos-
teriolateral edge of paranota 2–3 triangular, on 4th and onwards strongly pointed caudad (Fig. 14). Pore formula
normal, pores on paranota 5,7,9,10,12,13,15,16,17, and 18, in median excavation of paranota (in lateral view).
Sides between segments 6–13 perfectly parallel, segments 14–19 gradually tapering, posteriolateral projections
become more pointed. Epiproct in dorsal view subtriangular (Fig. 15), in lateral view protruding over paraprocts,
parallel-sided, slightly curved ventrad, with 7+7 setae, 3+3 of them sitting on knobs. Paraprocts strongly marginate
with 2+2 setae, hypoproct with 1+1 setae on knobs.
Midbody legs well separated (by 1.8–1.9 mm in males, 2.4–2.8 mm in females), sterna wide and smooth. Post-
gonopodal legs with moderately developed ventral spine on prefemur, increasingly stronger towards body end,
femur about twice as long as prefemur, straight, postfemur crassate, tibia straight, both subequal in length and
about 1/3rd of femur, tarsus slender, about twice as long as tibia, claw (ca. 0.5 mm long) curved.
Sexual characters: Male 2nd legpair (Fig. 16) coxa with strong median projections about half as long as length
of coxa, apically with membraneous tubules surrounded by strong setae, 1+1 macrosetae sitting at joint of prefemur
(1 anteriorly, and 1 posteriorly). No other sternal or leg modification could be observed. Male gonopodal aperture
on segment 7 wide, elliptical, about twice as wide as long, gonopods in situ usually deeply embedded, with acrop-
odites crossing each other. Coxa (Figs 17–18, c) long, slender, about twice as long as wide, without apophysis but
with small apophyseal macroseta (cm). Cannula normal, hidden on mesal side. Telopodite consists of two simple
processes (Figs 17–18) forming a simple, forceps-like appearance typical for Riukiaria (Tanabe & Shinohara
1996), the shorter branch being the prefemoral process (pfp), growing proximally from the base of prefemur, the
latter being thick and short, and densely covered with long hairs. Prefemoral process about 3/4th of length of acrop-
odite, devoid of any seta, knob, or additional process, flattened, parallel-sided, spatula-shaped, almost transparent.
Acropodite (as a continuation of prefemur) long, scythe-shaped, arched proximally towards prefemoral process,
with its slightly broadened to triangular, pointed tip (s) almost bending back to that. Distinction between prefemur
and acropodite indefinite, hairs becoming scarcier at about 1/3rd of total length, but about half length still a strong
macroseta (ms) on lateral side of acropodite. Prostatic groove runs straight medially along mesal side of acropodite,
and ends indistinctly on its pointed tip.
Female cyphopods (Fig. 19) closely packed behind 2nd legpair, in large, -shaped aperture, valves (v) are
oval, nearly as high as wide, densely setose, operculum (op) on lateral side small, less than half as high as valves,
with fewer and shorter but stronger setae, receptacles (r) embracing valves both anteriorly and posteriorly, subrect-
angular, with several series of short hairs only along ventral margin.
Distribution. R. mundyi sp. n. is restricted to Yonaguni-jima Island, the southwesternmost member of the
Yaeyama Island Group, southern Ryukyus, Okinawa Prefecture, Japan.
Remarks. Yonaguni-jima island, the type locality of R. mundyi sp. n., is situated about 100 km east of Taiwan,
and 80 km west of Iriomote-jima, another member of the Yaeyamas. On two of this latter island group, Iriomote-
jima and Ishigaki-jima islands, another species, R. chelifera, occurs. It is slightly larger (body length 45 mm), and
its color pattern is different: head, antennae, proterga, large part of metaterga anteriorly dark brown or grey, poste-
rior margin, paranota, tip of epiproct, and legs yellow. This is in strong contrast with the uniformly orange-yellow
color of the new species. Male gonopods also differ, acropodite and prefemoral process being straight, slender, and
almost equal in length, as opposed to the longer and curved acropodite with macroseta in R. mundyi sp. n.
Comparison to the possible Taiwanese species, R. cohaesiva, R. contigua, and R. uraensis (from the region of
Taipei, Wulai), all inadequately described and poorly illustrated by Wang (1956, 1957), is impossible without
freshly collected material.
KORSÓS ET AL.
66 · Zootaxa 2877 © 2011 Magnolia Press
Specimens of the new species in Yonaguni-jima were mostly collected along the edge of natural, deciduous
forests, mostly in moist litter under the large leaves of Alocasia odora, but also close to human-disturbed areas like
abandoned construction sites, ruined cave entrances etc. Adult specimens were collected at the locality Kubura-
bari, too, which is actually a pasture for the native, endemic race of horse (the Yonaguni pony), and these speci-
mens were distinctly smaller than members of the other populations. This is perhaps due to that relatively harsh
environment, the wind-swept rocky grassland on the western side of the island, generally poor in organic litter.
The species was mentioned and illustrated as an undescribed Riukiaria from Yonaguni-jima island by Tanabe
(2005). It was included into the Red Data Book of threatened wildlife of Okinawa and, though categorized as ’data
deficient’ (DD), its habitat was proposed for preservation. According to our observations, the species is not con-
fined to any characteristic or undisturbed biotope on Yonaguni-jima Island so perhaps habitat conservation is not
the best approach, but considering that the total area of the island itself is only 28.8 square kilometers, the popula-
tions of the new and unique species are indeed worthy of legal protection.
Discussion
With the present two new species the number of Riukiaria species in the Ryukyu Archipelago has increased from 9
to 11 (Table 1). According to our recent collecting, nine of them (81.8%) may be confined to single islands (vary-
ing in size from 28.8 to 1,201 km2). Yaku-shima (R. puella and jamila), Amami-O-shima (R. bifida and scutata),
and Okinawa-jima (R. falcifera, holstii, pugionifera) are the only islands which have more than one Riukiaria spe-
cies, whereas only one species, R. chelifera, seems to be shared by two islands (Ishigaki-jima and Iriomote-jima).
The status of ?R. holstii on Toku-no-shima is not yet clarified, it might be an introduction, or a separate, unde-
scribed species.
TABLE 1. Riukiaria species of the Ryukyu Archipelago. Islands (only those with Riukiaria species records) are listed from
north to south (for a map, and literature overview of the Archipelago, see Nakamura & Korsós 2010).
There are many more (around 140, only 64 being inhabited by humans) islands in the Ryukyu Archipelago, but
according to a tentative estimation, only about 75 islands can support native millipede fauna. Of them, we believe,
most (if not all) have already been discovered accommodating Riukiaria species, since these millipedes are rela-
tively large and colorful and have a conspicuous appearance. Their phylogenetic relationships, however, together
with the related fauna in the Japanese islands of Honshu, Shikoku, and Kyushu as well as that of Taiwan and east-
ern China is still unclarified.
Fluorescence is an interesting phenomenon in certain xystodesmid millipedes. When illuminated by UV-light
these animals, similarly to the well-known case of scorpions, strongly re-emit a greenish-bluish light. In contrast to
Island Japanese name Area (km2)Riukiaria species
Yaku-shima 504.9 R. puella Tanabe, 1988
R. jamila Tanabe, 1990
Tane-ga-shima 445.5 R. maculata sp. n.
Amami-O-shima 712.2 R. bifida (Takakuwa, 1942)
R. scutata (Takakuwa, 1942)
Toku-no-shima 247.8 ?R. holstii (Pocock, 1895)
Okinawa-jima 1,201 R. holstii (Pocock, 1895)
R. falcifera Verhoeff, 1936
R. pugionifera Verhoeff, 1936
Kume-jima 58.9 R. spiralipes (Takakuwa, 1942)
Ishigaki-jima 222.5 R. chelifera (Takakuwa, 1941)
Iriomote-jima 289.3 R. chelifera (Takakuwa, 1941)
Yonaguni-jima 28.8 R. mundyi sp. n.
Zootaxa 2877 © 2011 Magnolia Press · 67
TWO NEW RIUKIARIA SPECIES FROM THE RYUKYUS
active light emission (bioluminescence), fluorescence is a passive process, probably due to the structure of layers in
the cuticle, and can even be observed with dead specimens (freshly preserved ethanol specimens also show fluores-
cence). It also differs from phosphorescence where the object first absorbs the light energy then re-emits the radia-
tion only later. Bioluminescence (active light emission) has been well documented for the North American
xystodesmid millipede Luminodesmus sequoiae Loomis and Davenport, 1951 (Hastings & Davenport 1957), and
also observed in the related genus Motyxia Chamberlin, 1941 (Shelley 1997). The photoprotein responsible for
luminescence was found to be pterin-6-carboxylic acid, and the same compound was recently isolated from the
Japanese xystodesmid Parafontaria laminata armigera producing passive fluorescence (Kuse et al. 2010). For
both luminescence and fluorescence, the only plausible hypothesis was proposed as to warn predators (Shelley
1997). However, the function of passive glowing by totally blind polydesmidan millipedes, otherwise also produc-
ing a strong, cyanide defensive secretion, is still hard to understand. From the practical point of view, because of
the large size of Riukiaria specimens (4–6 cm), a strong UV flashlight can easily be used to find them in the night
of a warm subtropical forest. The color-pattern dependent fluorescence is also species-specific, so it might be use-
ful in the identification of the species, as well. In the color plates (Figs 2–5) here we present two examples of the
species-characteristic fluorescence pattern.
Acknowledgements
We would like to express our sincere gratitude to Prof. H. Ota (University of Hyogo) and M. Toda (Tropical Bio-
sphere Research Center, University of the Ryukyus, Okinawa) for accelerating taxonomical studies on millipedes
in the Ryukyus by inviting ZK for a research period. His study has also been supported by the Hungarian Scientific
Research Fund (OTKA No. 69235). Prof. N. Tsurusaki (Tottori University) supported us with extensive Japanese
literature, and Dr. H. Ono (National Museum of Nature and Science, Tokyo) provided specimen numbers for the
types. Two anonymous reviewers contributed to the improvement of the manucsript; we are very grateful to all of
them.
References
Attems, C.G. (1938) Myriapoda 3, Polydesmoidea II. Fam. Leptodesmidae, Platyrhachidae, Oxydesmidae, Gomphodesmidae.
In: Das Tierreich. Walter de Gruyter & Co., Berlin, 69, 486 pp.
Golovatch, S.I. (1978) [Some new East Asian millipedes (Diplopoda) in the collection of the Zoological Institute of the USSR
Academy of Sciences]. Entomologicheskoe Obozrenie, 57(3), 677–681. [In Russian]
Gressitt, J.L. (1941) New myriopods from Formosa and Hainan Island. Annals and Magazine of Natural History, Series 11,
8(43), 55–61.
Haga, A. (1968) [Japanese Millipedes]. Private publication, 11 pp. [In Japanese]
Hastings, J.W. & Davenport, D. (1957) The luminescence of the millipede, Luminodesmus sequoiae. Biological Bulletin 113,
120-128.
Hikida, T. & Ota, H. (1997) Biogeographical of reptiles in the subtropical East Asian Islands. In: Lue, K-Y. & Chen, T-H.
(Eds), Proceedings of the Symposium on the Phylogeny, Biogeography and Conservation of Fauna and Flora of East
Asian Region. National Science Council, Taipei, pp. 11–28.
Hoffman, R.L. (1949) A new genus of Xystodesmid millipeds from the Riu Kiu Archipelago with notes on related Oriental
genera. Natural History Miscellanea, 45, 1–6.
Hoffman, R.L. (1956) Studies on some Oriental xystodesmine millipeds (Polydesmida, Chelodesmidae). Proceedings of the
Entomological Society of Washington, 58(2), 95–104.
Hoffman, R.L. (1980) Classification of the Diplopoda. Muséum d’Histoire Naturelle, Genéve, 237 pp.
Kuse, M., Yanagi, M., Tanaka, E., Tani, N. & Nishikawa, T. (2010) Identification of a fluorescent compound in the cuticle of
the train millipede Parafontaria laminata armigera. Bioscience, Biotechnology, Biochemistry, 74(11), 2307–2309.
Miyosi, Y. (1952a) Beitrage zur Kenntniss japanischer Myriopoden. 4. Aufsatz: Ueber eine neue Art und eine neue Unterart
von Diplopoda. Zoological Magazine, 61(9), 281–282. [In Japanese with German summary]
Miyosi, Y. (1952b) Beiträge zur Kenntnis japanischer Myriopoden. 5. Aufsatz: Ueber zwei neue Arten von Diplopoda. Zoolog-
ical Magazine, 61(10), 314–316. [In Japanese with German summary]
Miyosi, Y. (1957) Beitrage zur Kenntniss japanischer Myriopoden. 22. Aufsatz: Über zwei neue Arten von Diplopoda. Zoolog-
ical Magazine, 66(10), 403–406. [In Japanese with German summary]
Motokawa, M. (2000) Biogeography of living mammals in the Ryukyu Islands. Tropics, 10, 63–71.
KORSÓS ET AL.
68 · Zootaxa 2877 © 2011 Magnolia Press
Nakamura, Y. & Korsós, Z. (2010) Distribution and diversity of millipedes of the Ryukyu Archipelago, with the Senkaku and
Daito Island Groups: A literature review (Arthropoda: Diplopoda). Acta Arachnologica, 59(2), 73–86.
Pocock, R.I. (1895) Report upon the Chilopoda and Diplopoda obtained by P. W. Bassett-Smith, Esq., Surgeon R. N., and J. J.
Walker, Esq., R. N., during the cruise in the Chinese Seas of H. M. S. ‘Penguin’, Commander W. U. Moore commanding.
Annals and Magazine of Natural History, Series 6, 15, 346–372.
Shelley, R.M. (1997) A re-evaluation of the millipede genus Motyxia Chamberlin, with a re-diagnosis of the tribe Xystocheirini
and remarks on the bioluminescence (Polydesmida: Xystodesmidae). Insecta Mundi, 11(3–4), 331–351.
Shinohara, K. (1977) Revaluation on Riukiaria (Diplopoda). Acta Arachnologica, 27 (special number), 115–119.
Sota, T. & Tanabe, T. (2010) Multiple speciation events in an arthropod with divergent evolution in sexual morphology. Pro-
ceedings of the Royal Society B, 277(1682), 689–696.
Takakuwa, Y. (1941) Rhysodesmus-Arten aus Japan. Transactions of the Natural History Society of Formosa, 31, 413–415.
Takakuwa, Y. (1942) Ueber weitere japanische Rhysodesmusarten. Transactions of the Natural History Society of Formosa,
32(224), 197–203.
Tanabe, T. (1988) Two new species of the genus Riukiaria from Kyushu and Is. Yaku-shima, Japan (Diplopoda: Polydesmida:
Xystodesmidae). Acta Arachnologica, 37, 37–45.
Tanabe, T. (1990) A new milliped of the genus Riukiaria from Is. Yaku-shima, Japan (Diplopoda: Polydesmida: Xystodesmi-
dae). Zoological Science, 7, 443–447.
Tanabe, T. (2005) [Millipedes]. In: Nature Conservation Division, Department of Cultural & Environmental Affairs, Okinawa
Prefectural Government (Ed.): [Threatened wildlife in Okinawa, second edition (Animals)—Red Data Okinawa]. Okinawa
Prefectural Government, Naha, Okinawa, pp. 298, 305–310. [In Japanese]
Tanabe, T., Ishii, K. & Yin, W-Y. (1996) Two new xystodesmid millipedes from the Tian-mu Mountains, Zhejiang Province,
China. Edaphologia, 57, 13–19.
Tanabe, T. & Shinohara, K. (1996) Revision of the millipede genus Xystodesmus, with reference to the status of the tribe Xys-
todesmini (Diplopoda: Xystodesmidae). Journal of Natural History, 30, 1459–1494.
Tömösváry, Ö. (1885) Myriopoda a Joanne Xantus in Asia Orientali collecta. Természetrajzi Füzetek, 9, 63–72. [In Latin]
Verhoeff, K.W. (1936) Zur Kenntnis ostasiatischer Strongylosomiden and Fontariiden. 149. Diplopoden-Aufsatz. Zoologischer
Anzeiger, 115, 297–311.
Wang, Y-H.M. (1956) Serica 1e: Records of myriapods on Formosa with description of new species (2). Quarterly Journal of
the Taiwan Museum, 9(2), 155–159.
Wang, Y-H.M. (1957) Serica 1g: Records of myriapods on Taiwan Islands (4) Six new polydesmids. Quarterly Journal of the
Taiwan Museum, 10(3–4), 103–111.
Wang, Y-H.M. (1960) On millipedes and centipedes from Taiwan, China. In: Verhandlungen der XI. Internationalen Kongress
für Entomologie. Wien, pp. 288–291.
Wang, D. & Zhang, Ch. (1993) Diplopoda, Chilopoda. In: Huang, Ch. M. (Ed.) Animals of Longqi Mountain. China Forestry
Publishing House, Beijing, (8), 845–851. [in Chinese with English summary]
