Bull. Natl. Mus. Nat. Sci., Ser. A, 38(1), pp. 13–19, February 22, 2012

A New Cavernicolous Species of the Tribe Batrisini(Coleoptera, Staphylinidae, Pselaphinae)
from the Ryukyus, Southwest JapanShûhei Nomura
Department of Zoology, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki, 305–0005 Japan
E-mail: nomura@kahaku.go.jp(Received 20 October 2011; accepted 28 December 2011)

Abstract A new cavernicolous species of Batrisini, Tribasodes kamedai is described from thelimestone cave, Nisshû-dô, Kin-cho, Okinawajima Is., the Ryukyus. This is the ﬁrst record of true
cavernicolous pselaphine from the Ryukyus.
Key words : Pselaphinae, Staphylinidae, Tribasodes, cavernicolous, Okinawajima Is.

Up to the present, three cavernicolous speciesof the pselaphine tribe Batrisini have been
known from Japan, Speobatrisodes punctaticeps
Jeannel, 1958 from Ryûga-dô Cave in Kôchi
Prefecture, Batrisodellus cerberus Tanabe etNakane, 1990 from Gongen-dô in Kumamoto
Prefecture, B. coprea Tanabe et Nakane, 1990
from Kugô-dô in Gifu Prefecture. No cavernicolous pselaphine has been known from theRyukyus. All cavernicolous species of the tribe
Batrisini from Japan belong to the genus groupof Batrisus deﬁned by Nomura and Idris (2003).
In the Chinese Continent, a cavernicolous
species of Batrisini, Batrisodellus carissimus
Nomura et Wang, 1991 has been known fromGuilin, S China. It was described as a new speciesof Batrisodellus, though it was moved to a newgenus, Tribasodellus by Yin et al., (2011), because
the species is not a member of the Batrisus
group, but that of the Tribasodes group (Nomuraand Idris, 2003).
Recently, a batrisine species was collectedfrom the limestone cave, Nisshû-dô, Kin-chô,Okinawajima Is. in the Ryukyus (Fig. 1). It was
not a member of the Batrisus group, but of theTribasodes group. This species is described as anew species, Tribasodes kamedai in the presentstudy. The genus Tribasodes was deﬁned byJeannel (1958), it contains three species
described from Japan.
Materials and methods
The material was examined by a scanningelectron microscope (SEM: JEOL JSM-6380LV).
For the SEM observations; all specimens werenon-coated, and examined with a low acv 0.9 kV.
Scale bars in all ﬁgures are in micrometres. Measurements of the body and parts were made witha stereo microscope (Leica MZ Apo).
The holotype and paratypes of this new species are deposited in the National Museum ofNature and Science, Tokyo (NSMT).
Tribasodes kamedai sp. nov.
[Japanese name: kura-hoso-munetoge-arizukamushi](Figs. 2–5)

Etymology. The new species is dedicated tothe collector of all the type specimens, Mr. Y.
Kameda, who is a scientist studying cavernicolous
mollusca.
Holotype male, Nisshû-dô Cave, Kin-chô,Okinawajima Is., Okinawa Pref., 7. vii. 2008, Y.14Shûhei Nomura

Fig. 1. The type locality of Tribasodes kamedai sp. nov., the limestone cave, Nisshû-dô, Kin-chô, Okinawajima Is.

Kameda leg. Paratypes: 2 females, same data asholotype; 2 females, same locality as holotype,but 18. v. 2011, Y. Kameda leg.
Description. Male (Fig. 2A, B). Body length
2.20 mm, width 0.72 mm, large and very slender,
weakly broadened in elytra and abdomen; color
reddish brown, mat on dorsal surface.

Head wider than long, nearly rectangular (Fig.
3A), with a pair of lateral carinae just insideeyes; clypeus short, arcuate on anterior margin;frons weakly concave, vertex convex, with a pairof dorsal tentorial pits between eyes; postgenaeslightly rounded. Eyes each small and ovoid,
composed of about 20 facets. Antennae 1.46 mm

New Cavernicolous Batrisini from Ryukyus

Fig. 2. Tribasodes kamedai sp. nov.: A, male habitus in dorsal view; B, ditto in ventral view; C, female habitus in dorsal
view; D, ditto in ventral view.

15

16Shûhei Nomura

Fig. 3. Tribasodes kamedai sp. nov.: A, C, E, G, male; B, D, F, H, female; A, B, head and thorax in dorsal view; C, D,ditto in ventral view; E, F, antennae; G, H, antennal segments IX to XI.

New Cavernicolous Batrisini from Ryukyus

Fig. 4. Tribasodes kamedai sp. nov.: A, C, E, G, male; B, D, F, H, female; A, B, meso- and metathoraces in ventral view;
C, D, hind trochanter in ventral view; E, F, elytra; G, H, abdomen in dorsal view.

1718Shûhei Nomura

Fig. 5.

Tribasodes kamedai sp. nov.: A, male genitalia in dorsal view; B, ditto in ventral view.

in length, very long and very slender (Fig. 3E);
segment I thick, cylindrical, weakly angulate atinternal and external apices; segments I to IV
subequal in length, each subcylindrical; II to VIII
subequal in width;V slightly longer than IV; VIII
shorter than VII, ovoid, slightly longer thanwide; IX to X subequal in width, each ovoid,
longer than wide (Fig. 3G); XI the largest,slightly wider than X (Fig. 3G), slightly longer
than IX＋X, weakly constricted near base.
Maxillary palpi each elongate and short (Fig.
3C); segment IV the largest, fusiform, about aslong as I＋II＋III.
Pronotum slightly longer and slightly wider
than head (Fig. 3A), wider than long, with a pairof short lateral spines near the middle; broadened
before lateral spines, constricted just behindlateral spines, with a pair of large lateral foveae
at basal 2/5, and a pair of weak conical dorsal
denticles just inside lateral foveae; with two pairsof parallel longitudinal carinae, each inner carina
running from anterior margin to lateral fovea,
and each outer carina from anterior margin todorsal denticle; and with a median longitudinalgroove in anterior 4/5. Metasternum (Fig. 4A)

broad and transverse, with large triangular protuberance between meso- and metacoxae. Metatrochanters each short and triangular, with a large
and T-shaped spine at apex on posterior side(Fig. 4C). Elytra wider than long, trapezoidal,
broadened posteriorly (Fig. 4E), each with threebasal foveae, long adsutural and short lateralcarinae.
Abdomen longer than elytra, slightly longer
than wide (Fig. 4G), segments IV to VIII successively shortened posteriad; IV the largest, transverse, with a pair of narrow paratergite on bothlateral sides, with a pair of large lateral fovea
along basal margin, and with a pair of very
shallow and indistinct concavities. Male genitalia
weakly sclerotized (Fig. 5A, B); median lobe
ﬂattened dorso- ventrally, narrowed and nearlymembranous in dorsoapical part; basal capsulevery large and rounded, with a very large andovoid basal foramen; ventral stalk short, narrowed distally.
Female (Figs. 2C, D, 3B, D, F, H, 4B, D, F,H). Body length 2.05–2.32 mm, width 0.65–0.71 mm, antennal length 1.37–1.47 mm. Verysimilar to male, but different in the following

New Cavernicolous Batrisini from Ryukyus

characters: eyes smaller than in male, ovoid,each composed of about 15 facets; metasternal
protuberance smaller than that of male (Fig. 4B);
hind trochanter without spine at apex (Fig. 4D).
Distribution. Okinawajima Is.
Remarks. This new species is similar to theother members of the genus Tribasodes, but isseparable by very slender body, very long antennae, the male trochanter with T-shaped spine, andvery weakly sclerotized male genitalia with shortventral stalk.
Acknowledgements
I wish to express my hearty thanks to Dr.
Shun-Ichi Uéno for his critical reading of themanuscript. Our cordial thanks are due to Mr.
Yûta Nakase for his kind assistance in examina-19

tion of type material.
This work was supported in part by theNational Museum of Nature and Science, Tokyo
as the study project titled “Integrated research on
biodiversity of interspecies relationships”.
References
Jeannel, R. (1958). Révision des Psélaphides du Japon.
Mém. Mus. Hist. nat., Paris, (A), 18: 1–138.
Nomura, S. and A. G. Idris, (2003). Faunistic notes on thebatrisine species from Malaysia and Singapore (Coleoptera:Staphylinidae: Pselaphinae). Serangga, Bangi, 8:55–72.
Yin, Z.-w., S. Nomura and M.-j. Zhao (2011) Taxonomic
study on Batrisodellus Jeannel of China, with discussion on the systematic position of Batrisodellus callissimus Nomura & Wang, 1991 (Coleoptera, Staphylinidae, Pselaphinae). Spixiana, München, 34: 33–38.