Bull. Natl. Mus. Nat. Sci., Ser. A, 49(4), pp. 123–127, November 22, 2023
DOI: 10.50826/bnmnszool.49.4_123

New Records of Chikunia subrapulum (Zhu, 1998), n. comb., (Araneae:
Theridiidae) from Japan, with Taxonomical and Nomenclatural Notes
Ken-ichi Kumada1 and Hirotsugu Ono2, *1

5010, Takanoo, Tsu, Mie 514–2221, Japan
E-mail: Haraobihimegumo@yahoo.co.jp
2
Department of Zoology, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki 305–0005, Japan*E-mail: ono@kahaku.go.jp(Received 28 July 2023; accepted 20 September 2023)

Abstract Specimens of 53 females and 11 males of an unknown spider species from the family
Theridiidae in Japan were taxonomically studied. The spider is identiﬁed as Chrysso subrapulum
Zhu, 1998 known only from males from China, which is recorded here from Japan for the ﬁrst
time. This species is described based on the Japanese specimens, including hitherto unknown
females, and is transferred from the original genus Chrysso O. Pickard Cambridge, 1882 to thegenus Chikunia Yoshida, 2009 via a comparative examination of morphological characteristics. A
nomenclatural problem with the speciﬁc name of this spider is discussed and its original spellingmust be used for it.
Key words: Taxonomy, spiders, Chrysso, new combination, new records, nomenclature.

Introduction
The theridiid genus Chikunia established by
Yoshida (2009) contains three described species,
Chikunia albipes (Saito, 1935) (＝Theridion
rapulum Yaginuma, 1960) from Japan, China,
Korea and Russian Far East, Chikunia bilde
Smith, Agnarsson & Grinsted, 2019 from Malaysia, Singapore and Indonesia and Chikunia nigra(O. Pickard-Cambridge, 1880) widely distributed
from India to Indonesia and Taiwan (World Spider Catalog, 2023). Of these, only Chikunia albipes, the type species of the genus, was so far
known from Japan (Yoshida, 2001, 2009b; Ono
and Ogata, 2018; Tanikawa, 2023).
However, the ﬁrst author, Kumada, hadnoticed, but not published, a diﬀerent species oftheridiid spider similar in appearance to the common Chikunia albipes in Japan about 30 years
ago. The ﬁrst specimen examined was a female© 2023 National Museum of Nature and Sciencecollected by Ms. Shigeyo Inaba during an excursion in Kagoshima Prefecture, Kyushu, held after
the 21st annual meeting of the ArachnologicalSociety of Japan at Miyazaki in the summer of
1989. Subsequently he collected females andmales of this unknown species many times sincein Kyushu, Shikoku, and Honshu. Although hereserved the records for a long time, he came tothe conclusion that the unknown species is thesame as Chrysso subrapulum described by Zhu(1998) based on a male specimen collected in
Hubei, China.
After a careful examination based on suﬃcientmaterials, both the authors have discovered new
data reported here. First, this species is recordedin Japan for the ﬁrst time. Second, the previously
unknown female of the species has been discovered and hereby described for the ﬁrst time.
Third, this species should be transferred from its
original genus Chrysso O. Pickard Cambridge,
1882 to the genus Chikunia which was recently
established by Yoshida (2009a). Finally, the spe-

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K. Kumada and H. Onocies epithet of the scientiﬁc name of this species
should be returned to its original spelling.
Abbreviations used are as follows: ALE, anterior lateral eye; AME, anterior median eye;
AME–AME: distance between AMEs; AME–
ALE: distance between AME and ALE; PLE,
posterior lateral eye; PME, posterior median eye.
Taxonomy
Chikunia subrapulum (Zhu, 1998), n. comb.
[Japanese name: Kabura-himegumo](Figs. 1–9)
Chrysso subrapulum Zhu, 1998, p. 47, 65, 361, 390, ﬁg.
37 A–C, ♂ holotype from Hefeng County (29.48N,
110.00E), Hubei Province, China, 1–VI–1989, M.-S.
Zhu leg., preserved in the Chinese Academy of Sciences, not examined. — Song, Zhu & Chen, 1999, p.
107, ﬁg. 50 M–N; Zhu et al. 2005, p. 496.
Chrysso subrapula Zhu and Zhang, 2011, p. 88, ﬁg. 49
A–C; WSC, ver. 24, 2023, the list for Theridiidae. —Incorrect emendation of the species name. New synonymy.
Theridiidae sp.: Bando, 2021, p. 3, ﬁg. 14, 1 ♀, Nakao,
Funatsu, 30–VII–2020, 1 ♀, Kamikaitsu, Aikawa, 3–
VIII–2020, both from Kaiyo-cho, Kaifu-gun,
Tokushima Prefecture, Shikoku, Japan, H. Bando leg.,preserved in the Tokushima Prefectural Museum(TKPM), not examined.

Etymology. The modiﬁcation of the endingof the species name made by Zhu and Zhang(2011) was grammatically incorrect and wasregarded as the suggestion of a new name by anincorrect emendation. The present authors havechanged the species name back to the original
spelling in accordance with the terms (article
11.9, 33.2 and others) of the International Codeof Zoological Nomenclature (ICZN). In detail,Zhu (1998) named it sub-+rapulum because of
its resemblance to Theridion rapulum Yaginuma,
1960, originally described from Japan. However,the Japanese spider has a diﬀerent name (a seniorsynonym), Chikunia albipes (Saito, 1935), at thepresent, and its distributional range extends to
Korea, China and the Russian Far East as well asJapan. Theridion rapulum was transferred fromits original genus Theridion Walckenaer, 1805 to

Chrysso O. Pickard-Cambridge, 1882 by Yoshida(1993) and synonymized with Theridula albipes
Saito, 1935 by Yoshida (2001), and ﬁnally, further transferred to the genus Chikunia establishedwith this species as the type species by Yoshida(2009 a). Although the motive for naming ofTheridion rapulum was not stated in the originaldescription, Yaginuma explained its etymology
on another occasion. In Yaginuma, Hirashima
and Okuma (1990), p. 142, they stated that rapulum is a Latin word (a neuter noun) meaning alittle turnip (rapum with diminutive) because theshape of the abdomen of the spider resembled theshape of the vegetable. Therefore, the speciesname made by a noun in apposition does notchange its ending when the gender of the genus
changes. The problem would not have arisen if
the genitive case of the noun, rapuli, or theadjective rapinus, -a, -um or rapiformis, -is, -e
had been used, but the word used in reality isclearly the nominative of a noun. Moreover,because Latin grammar indicates that the preﬁx
sub- changes to sur- when attached to a word
beginning with r, the species name made by sub+rapulum should be expressed as surrapulum inthe nominative case, and surrapuli in the genitivecase. Unfortunately, this grammatically correctchange is not permissible under the agreement of
ICZN, thus the original spelling subrapulum has
to be maintained.
Specimens examined. 1 ♀, 10–IX–2015,1 ♀1 ♂, 11–VIII–2016, 2 ♂, 12–VI–2017, 3 ♀,24–VIII–2017, 1 ♀, 7–IX–2018, 1 ♂, 3–
VI–2020, Ikenotaira, Tatsue, Iida-shi, Nagano
Pref., Honshu, Japan (35.4502N, 137.8422E);
1 ♂, 17–VI–2021, Shimo-hisakata-kakinosawa,
Iida-shi, Nagano Pref., Honshu, Japan(35.4607N, 137.8499E); 1 ♀, 21–VIII–1990,
Sagasawa, Kadonohara, Amagi-yugashima-cho,
Tagata-gun, Shizuoka Pref., Honshu, Japan(34.9007N, 138.9239E); 7 ♀, 7–IX–2013, Takitaniike, Makiyama, Iga-shi, Mie Pref., Honshu,
Japan (34.8840N, 136.1117E); 7♀juv. 2♂juv.,
12–IV–2008, 1 ♀, 27–IV–2008, 1 ♀1 ♂, 9–V–
2008, 6 ♀1 ♂, 23–V–2008, 1 ♀, 12–VI–2009,

New records of Chikunia subrapulum from Japan125

Figs. 1–9. Chikunia subrapulum (Zhu, 1998). 1–2, female and male, dorsal view; 3–4, male left palp, ventral
view; 5–6, epigynum, ventral view; 7–8, epigynum, lateral view; 9, chelicerae, ventral view. Scales: 1–2:
1 mm; 3–9: 0.1 mm.

8 ♀, 13–VI–2009, 9 ♀1 ♂, 9–VII–2010,
Higashi-iketani, Hojo-cho-higashitakamuro,Kasai-shi, Hyogo Pref., Honshu, Japan(34.9159N, 134.8485E); 1 ♀1 ♂, 13–VIII–2011,
Tsurarakannon, Wajikigo, Naka-cho, Naka-gun,
Tokushima Pref., Shikoku, Japan (33.8672N,
134.4962E); 3 ♀, 19–IX–2011, Oto, Kitagawauchi, Minami-cho, Kaifu-gun, Tokushima Pref.,Shikoku, Japan (33.7669N, 134.5400E); 1 ♀,30–IX–2013, Ikenouchi, Awai-cho, Kanonji-shi,
Kagawa Pref., Shikoku, Japan (34.0711N,

133.7136E), all the above specimens were collected by K. Kumada; 1 ♀, 21–VIII–1989,
Imuta-ike, Imuta, Kedoin-cho, Satsuma-gun,Kagoshima Pref., Kyushu, Japan (31.8144N,
130.4659E), S. Inaba leg. Of these, voucher
specimens are deposited in the arachnid collection of the Department of Zoology, National
Museum of Nature and Science, Tsukuba, Japan.
Diagnosis. The species is transferred fromits original genus Chrysso O. Pickard Cam-

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K. Kumada and H. Ono

bridge, 1882 to the genus Chikunia Yoshida,2009 based on the following characteristics: Legsof the females of this species are short, the total
length of the ﬁrst patella and tibia of the palp is
1.4 times the length of the carapace in dorsal
view, whereas that of Chrysso species is morethan 1.8 times. The shoulders of each side of thefemale abdomen are rounded, projected andexpanded horizontally, the posterior end (tail) of
the abdomen is long, pointed and projecting
beyond the spinnerets. The male abdomen is
ovoid, unscaled, and the shape of embolic partwith the embolus and the conductor is triangular.
This species is closest to Chikunia albipes.
Description based on the Japanese specimens(1 ♀1 ♂ from Higashi-iketani, Hojocho-higashitakamuro, Kasai-shi, Hyogo Pref., Honshu,
Japan, 9–VII–2010). Female (Fig. 1, left): total
length 2.78 mm. Carapace 0.84 mm long and0.76 mm wide. Abdomen 2.10 mm long and2.24 mm wide. Length of leg segments (in mm):[femur+patella+tibia+metatarsus+tarsus＝total]:I, 1.28+0.32+0.84+0.96+0.40＝3.80; II, 0.86+
0.28+0.44+0.58+0.34＝2.50; III, 0.56+0.24+
0.24+0.34+0.28＝1.66; IV, 1.10+0.30+0.62+
0.66+0.40＝3.08. Leg formula: 1-4-2-3. Prosoma
oval. Eyes almost same in size except PLE
smaller than the others. AME＝ALE＝PME＞
PLE(5 : 5 : 5 : 4). AME–AME＞AME–ALE(3 : 1), PME–PME＞PME–PLE (4 : 5). The anterior eye row recurved and the posterior eye row
slightly recurved in dorsal view. Median oculararea: anterior side＞posterior＝length (6 : 5 : 5).
Clypeus longer than AME–AME (2 : 1). Chelicerae not very long and thick (1.90 mm), with two
projections (possibly teeth) near the apex.
Labium transverse, longer (5 : 3), fused with sternum. Sternum inverted triangular, equal in length
and width. Shoulders on both sides of abdomenrounded, swollen and expanded laterally; abdomen with long caudal end, projecting beyond thespinnerets and pointed. The length of ﬁrst patella
and tibia 1.4 times the carapace length. Epigynum (Figs. 5–8) expanded and protruding ventrad.

Male (Fig.1 right): total length 1.81 mm. Carapace 0.80 mm long and 0.66 mm wide. Abdomen
1.00 mm long and 1.02 mm wide. Length of leg
segments (in mm): I, 1.50+0.36+0.94+1.18+0.41＝4.39; II, 1.05+0.32+0.59+0.73+0.38＝3.07;
III, 0.60+0.24+0.33+0.46+0.26＝1.89; IV, 1.18+
0.28+0.75+0.82+0.40＝3.43. Leg formula: 1-42-3. Prosoma oval. Eyes almost equal in size
except PLE smaller than the others. AME＝
ALE＝PME＞PLE (5 : 5 : 5 : 4). AME–AME＞
AME–ALE (4 : 1), PME–PME＞PME–PLE(3 : 4). The anterior eye row recurved and theposterior eye row slightly recurved in dorsal
view. Median ocular area: anterior side＞
posterior side＝length (6 : 5 : 5). Clypeus longer
than AME–AME (2 : 1). Chelicerae not very longand thick (1.90 mm), with two projections (possibly teeth) near the apex. Labium transverse, longer (2 : 1), fused with sternum. Sternum inverted
triangular, equal in length and width. Abdomen
spherical. The conductor of palp and embolus
forming a triangle (Figs. 3–4).
Distribution. Japan (Honshu, Shikoku andKyushu), China (Hubei, Henan, Guizhou andYunnan).
Remark. By the reviewerʼs suggestion, theauthors conﬁrmed that the unknown theridiid spider recorded by Bando (2021) from Tokushima
Prefecture was the same species as the present
one. Its collection record has been added to thetransition list of scientiﬁc names above.
Acknowledgments
The authors would like to thank Ms. Shigeyo
Inaba for providing specimens for this study.
Many thanks are due to Dr. Jason A. Dunlop, Dr.
Ken-ichi Okumura and Mr. Yuya Suzuki for theirhelpful advices and reviewing the manuscript,
and to Mr. Haruo Bando for providing valuable
information. This paper is dedicated to the lateDr. Hajime Yoshida and Dr. Ming-sheng Zhu
who contributed greatly to the taxonomy of Theridiidae.

New records of Chikunia subrapulum from Japan

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