Breviora

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B RE VI O R A

Nk nisemm oi ^omniparafave /^oology

us ISSN 0006-9698

Cambridge, Mass. 20 April 2000 Number 509

ASPECTS OF LIFE HISTORY, ECOLOGY,

AND DISTRIBUTION OF THE ASIATIC FOUR-LINED

SKINK, EUMECES QUADRILINEATUS, IN SOUTH

CHINA

James Lazell^ and Hidetoshi Ota^

Abstract. The life history of Eumeces quadhlineatiis in South China appears
correlated to the southwest, wet monsoon. Females with a snout-vent length
(SVL) greater than 71 mm contain shelled eggs in late March and lay clutches of
two to six eggs in May, the beginning of the monsoon. Hatchlings appear in late
June and early July, measuring 25-33 mm SVL, and grow to at least 51 mm,
possibly 58 mm, SVL by early October, the end of the monsoon. Mature size is
attained during their second monsoon season, but females probably do not lay
eggs until the beginning of their third at ca. 34.5 months of age. Most common
in the coastal zone, this species may occur to ca. 500 m in open areas. Tai Yue
Shan (Lantau Island), Shek Kwu Chau, and Kau Sai Chau are new islands of
record.

An uncommon skink except on the southern part of Cheng Chau .... Else-
where ... if any are seen, the numbers are generally small.

— Karsen, Lau, and Bogadek (1986)

INTRODUCTION

The Asiatic four-lined skink, Eumeces quadrilineatus (Blyth,
1853) is little known and apparently rarely encountered except

' Department of Herpetology, Museum of Comparative Zoology, Harvard Uni-
versity, Cambridge, Massachusetts 02138, U.S.A., and The Conservation Agency,
6 Swinburne Street, Jamestown, Rhode Island 02835, U.S.A.
2 Tropical Biosphere Research Center, University of the Ryukyus. 1 Senbaru, Ni-
shihara-cho, Okinawa 903-01, Japan.

B RE V I O R A

iiseminn of C^onnparafive /1/oology

us ISSN 0006-9698

Cambridge, Mass. 20 April 2000 Number 509

ASPECTS OF LIFE HISTORY, ECOLOGY,

AND DISTRIBUTION OF THE ASIATIC FOUR-LINED

SKINK, EUMECES QUADRILINEATUS, IN SOUTH

CHINA

James Lazell' and Hidetoshi Ota-

Abstract. The life history of Eumeces quadrilineatus in South China appears
correlated to the southwest, wet monsoon. Females with a snout-vent length
(SVL) greater than 71 mm contain shelled eggs in late March and lay clutches of
two to six eggs in May, the beginning of the monsoon. Hatchlings appear in late
June and early July, measuring 25-33 mm SVL, and grow to at least 51 mm,
possibly 58 mm, SVL by early October, the end of the monsoon. Mature size is
attained during their second monsoon season, but females probably do not lay
eggs until the beginning of their third at ca. 34.5 months of age. Most common
in the coastal zone, this species may occur to ca. 500 m in open areas. Tai Yue
Shan (Lantau Island), Shek Kwu Chau, and Kau Sai Chau are new islands of
record.

An uncommon skink except on the southern part of Cheng Chau .... Else-
where ... if any are seen, the numbers are generally small.

— Karsen, Lau, and Bogadek (1986)

INTRODUCTION

The Asiatic four-lined skink, Eumeces quadrilineatus (Blyth,
1853) is little known and apparently rarely encountered except

' Department of Herpetology, Museum of Comparative Zoology, Harvard Uni-
versity, Cambridge, Massachusetts 02138, U.S.A., and The Conservation Agency,
6 Swinburne Street, Jamestown, Rhode Island 02835, U.S.A.
2 Tropical Biosphere Research Center, University of the Ryukyus, 1 Senbaru, Ni-
shihara-cho, Okinawa 903-01, Japan.

BREVIORA

No. 509

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Figure 1. A generalized range of Eumeces quadrilineatus from the literature.
1, Thailand, "Siam" of Pope (1935). 2. northern Vietnam, "Tonkin" of Pope
(1935). 3. Guangxi (Zhao and Adler, 1993). 4, Hainan, "mountains south of No-
doa" (Pope. 1935). 5, Guangdong; dot indicates Dinghushan, for MCZ 170517;
circled area is detailed in Figure 2. Bar is 200 km.

on some continental shelf islands in tropical Ciiina. Pope (1935)
examined only 1 3 specimens, of which but six came from China:
three from Dinghushan ("Tinghushan"), Guangdong; one from
south of Nodoa, Hainan Dao; and two from Hong Kong. Zhao
and Adler (1993) include Guangxi within the range, between
Guangdong and Tonkin, North Vietnam (Fig. 1). Karsen et al.
(1986) recorded the species on Cheung Chau island just south-
west of Hong Kong, Lazell (1988) on Tai A Chau, Soko Islands,
also in Hong Kong Territory, and Lazell et al. (1997) on Wai
Ling Ding in the Wanshan archipelago, Guangdong Province
(Fig. 2).

The closest relatives of Eumeces quadrilineatus live not in Asia
but in North America. Taylor (1935) placed it closest to E. egre-
gius of Florida, Georgia, and Alabama, whereas Lieb (1985) al-
lied it with the E. skiltonianus group of western North America.
A study of its karyotype by Kato et al. (1998) did not include
comparison to E. egregius and, although no differences were de-
termined from the skiltonianus group, the 2n = 26 configuration
is typical of the Pariocela section of the genus. The relationships
of Eumeces quadrilineatus will probably only be resolved bio-
chemically. It is biogeographically notable that Eumeces quad-

1999 ASPECTS OF EUMECES QUADRIUNEATUS IN SOUTH CHINA

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Figure 2. The Wanshan archipelago and Hong Kong region. Dots indicate
locaUties for Eumeces quadriUneatus examined in the present study. Islands are:
1 Hong Kong. 2, Tai Yue Shan (Lantau). 3, Tai A Chau, Soko Islands. 4, Shek
Kwu Chau. 5, Cheung Chau. 6, Wai Ling Ding. Most of the Wanshans, south and
west, are virtually unexplored herpetologically. Bar is 10 km.

rilineatus is one of the few tropical species in Asia fitting a clear-
ly trans-Beringian pattern of relationship (Lazell and Lu, 1999).

LIFE HISTORY

Hosono and Hikida (1999) reported two captive females that
laid a total of five eggs, four of which hatched (Table 1 and Fig.

BREVIORA

No. 509

Table 1. Female eumeces quadrilineaws and characteristics of their egg
clutches.

Snout-

vent

No.

Length

Width

Specimen

length

eggs

(mm)

(mm)

Date

Condition

MCZ 172787

72

4

9-11

6

27 March 1987

Oviductal,
shelled

MCZ 172788

77

6

5.5-6

5-6

25 March 1987

Oviductal.
shelled

KUZ 45250

75

2

14-17 May 1997

Laid

KUZ 4525 1

73

3

18 May 1997

Laid

3). Both females were from the Cheung Chau population: Kyoto
University Museum of Zoology (KUZ) 45250-1. Another Cheung
Chau female. Museum of Comparative Zoology (MCZ) 172787,
contained four shelled eggs, and one from Tai A Chau, Soko
Islands, MCZ 172788, contained six; both lizards were collected
in late March (Table 1). Two Cheung Chau females contained
large ovarian follicles: KUZ 36508, collected 26 September 1996,
had a maximum follicle diameter of 5.3 mm; KUZ 30397, col-
lected 4 October 1994, had a maximum follicle diameter of 3.0
mm.

By far the largest specimen examined is an adult male, KUZ
39301, with a snout-vent length (SVL) of 86 mm, collected on
Cheung Chau. The 10 largest males are 70-86 mm (average 75
rrmi) SVL. Females are slightly smaller: the largest, MCZ 177079
from Shek Kwu Chau, is 79 mm SVL. The 10 largest females
are 67-79 mm (average 72 mm) SVL. The difference between
the sexes is not significant given our sample sizes. Determining
sex usually requires dissection and is uncertain with small spec-
imens. Thus, in the ontograph (Fig. 3) we have not separated the
sexes.

Hatchlings grow rapidly during their first wet monsoon season
at an average rate of at least 0.22 mm/day, or 1 mm every 4.5
days, calculating from the ontograph (Fig. 3) and assuming sim-
ilar hatching times and growth rates in different years. Such an
assumption is hazardous (see below). Growth might be even more
rapid, depending on the ages of the specimens. Three specimens

1999 ASPECTS OF EUMECES QUADRIUNEATUS IN SOUTH CHINA

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Figure 3. Ontograph of Eumeces quadrilineatus. Anows indicate: 1. range of
first wet monsoon growth, and 2, specimens entering their second growth season.
The question-marked range includes specimens of uncertain age (see text). Sym-
bols identify populations on different islands: Solid dots, Cheung Chau. Small
circles, Tai Yue Shan (Lantau). Triangles, Tai A Chau, Soko Islands. Squares,
Shek Kwu Chau. Asterisk, Kau Sai Chau. Star, Wai Ling Ping. D, Dinghushan.
X, Hong Kong. The four gravid females are circled (see text).

6 BREVIORA No. 509

collected 26 September 1991 (MCZ 176655) and 4 October 1994
(KUZ 36163 and 36168) were 58-55 mm SVL. Because these
specimens fall within the range of those collected in March,
which must be ca. 8.5 months old, we cannot be certain they are
only ca. 90 days old (Fig. 3, but see below).

The circumstantial evidence of size and reproductive condition
implies that during their second wet monsoon season, growth
slows to about one-third that of the first season to ca. 0.08 mm/
day, or 1 mm every 12.5 days. Most specimens can apparently
attain ca. 70 mm SVL during their second season. However, be-
cause most females this size have ovaries containing small fol-
licles (<2 mm) and thin oviducts, we believe no females repro-
duce until the next year at about 22.5 months. We believe most
breeding females are likely to be even older, ca. 34.5 months,
because all six certainly reproductive specimens we have exam-
ined (i.e., those with vitellogenic ovarian follicles larger than 2.5
mm or oviductal eggs at capture) were 71-78 mm (average 74
mm) SVL (MCZ 172787-8; KUZ 54250-1, 30397, and 36508).

We hazard the guess that the 86-mm male, KUZ 39301, was
at least 4 years old (Fig. 3).

ECOLOGY

Dudgeon and Corlett (1994) provide a comprehensive and con-
cise overview of the climate of the coast of tropical China. Ba-
sically and modally, little rain falls in December, January, and
February. Average daily temperatures during these 3 months are
typically below 20°C. Rainfall increases March to May and usu-
ally exceeds 200 mm/month by June. Temperatures increase con-
cordantly to rather consistently exceed 20°C. Warm, wet condi-
tions prevail through September into early October. All of this is
the result of the monsoonal wind directions superimposed on the
northeast trade wind regime of this latitude. Initially, in October,
the northeast monsoon is the trade wind, unaltered by the Eur-
asian continent. As the continental interior cools, colder, denser
air flows outward and the winds shift to dry northerlies. With the
advent of continental, temperate spring, the warmed air rises,
drawing in a wind off the South China Sea to the southwest. As
the wet monsoon progresses through the "summer" months, the

1999 ASPECTS OF EUMECES QUADRILINEATUS IN SOUTH CHINA 7

winds shift progressively to southerlies, and eventually southeast-
erlies, until the cycle repeats itself.

For small reptiles like skinks, virtually all growth must take
place during the warm, wet, summer monsoon from May to Oc-
tober. This is the case with the skink Scincella modesta (Lazell
et ai, 1997), but that small species can attain adult size in a single
season. The much larger Eumeces quadhlineatus certainly re-
quires two seasons to reach adult size (Fig. 3).

Dudgeon and Corlett (1994) also provided detailed data on the
vicissitudes of temperature and rainfall among years. Some of
their data bear directly on our problem of aging September-Oc-
tober skinks 55-58 mm SVL. Could MCZ 176655, 58 mm SVL,
collected 26 September 1991 on Shek Kwu Chau, be only ca. 90
days old? Dudgeon and Corlett (1994:10) showed that the wet
monsoon of 1991 was notably late-shifted with monthly rainfall
averages ca. 300 mm from June through October. If MCZ 176655
was only ca. 90 days old in late September, it might have grown
considerably more had it survived another 30 days.

By contrast, MCZ 172791 (53 mm SVL) collected on Tai Yue
Shan (Lantau) 16 March 1987 and MCZ 173399 (56 mm SVL)
collected on Tai A Chau, Sokos, 27 March 1987 are the smallest
among the presumptive second-year specimens. Dudgeon and
Corlett (1994:10) show that the preceding 1986 wet monsoon
peaked in July. Rainfall averages dropped well below 300 mm in
both August and September and dropped below 100 m in October.

It has been reported that in tropical regions the abundance of
insects, the principal prey of skinks, is influenced by precipitation
(e.g., Auffenberg and Auffenberg, 1989, and references cited
therein). Thus, monsoon conditions may well account for appar-
ent growth discrepancies in Eumeces quadhlineatus through fluc-
tuations in prey abundance from year to year.

DISTRIBUTION

Eumeces quadhlineatus is most often found in the early serai
stages of terrestrial succession just inland from the sea. This spe-
cies is also occasionally found in disturbed, early serai stage hab-
itats higher and further inland. The fact that these skinks are al-
most always found under cover and are rarely observed in the

8 BREVIORA No. 509

open or basking contrasts with their predilection for open habitats
depauperate in vegetation. We have never found Eumeces quad-
hlineatus in forest.

Coastal wrack, exposed rock and junk piles, and old buildings
are the most frequent habitats of Eumeces quadrilineatus. Karsen
et al. (1986:63) say "in areas adjoining woodland," which was
the case for MCZ 179529 collected under junk at the fungshui
woods edge at Kau Sai village, Kau Sai Chau, 5 July 1994. The
large adult MCZ 177079 was captured inside an infrequently used
storage building on Shek Kwu Chau; MCZ 179461 was captured
inside an abandoned, collapsing building on Wai Ling Ding (La-
zell et al, 1997); MCZ 170517 was found inside a Httle concrete
hut at the top of Shan Bao Feng, 491 m elevation, in Dinghushan,
Guangdong.

On Tai Yue Shan (Lantau), concrete catchwaters have yielded
MCZ 176223 at Ma Po Ping and MCZ 177078 at Shek Pik, both
ca. 100 m elevation. Another Tai Yue Shan specimen, MCZ
181781, a 30-mm SVL hatchling, was found dead on the road at
the inland edge of Sham Wat Wan village beside an abandoned
paddy.

The early serai stage and edificarian habitats of Eumeces quad-
rilineatus are enigmatic in view of its seemingly relictual distri-
bution. This species is regularly encountered only on continental
shelf islands like Tai A Chau, Shek Kwu Chau, and Tai Yue Shan.
It is, however, vouchered present on only seven islands (Fig. 2),
and is nowhere abundant except on one: Cheung Chau, Hong
Kong region.

Cheung Chau is largely urbanized and the remaining open
spaces need to be given special conservation consideration, if
only to preserve the mother lode of disjunct, peculiar Eumeces
quadrilineatus.

ACKNOWLEDGMENTS

We are indebted to Stephen Karsen, Fr. Anthony Bogadek, Mi-
chael Lau, Numi Mitchell, Glenn Mitchell, Gary Fournier, Szu-
Lung Chen, Setsuko Iwanaga, Wong Chi Keung, and Barrie Hol-
linrake for collecting specimens and to Junko Kato for laboratory
assistance. Our work was supported by Earthwatch, the St. Louis

1999 ASPECTS OF EUMECES QUADRILINEATUS IN SOUTH CHINA 9

School, the Explorers Club, the University of Hong Kong, and
The Conservation Agency.

LITERATURE CITED

AuFFENBERG, W., AND T. AuFFENBERG. 1989. Reproductive patterns in sympatric
Philippine skinks (Sauria: Scincidae). Bulletin of the Florida State Museum,
Biological Sciences, 34(5): 201-247.

Blyth, E. 1853. Notices and descriptions of various reptiles, new or little known.
Journal of the Asiatic Society of Bengal, 22(7): 639-655.

Dudgeon, D., and R. Corlett. 1994. Hills and Streams: An Ecology of Hong
Kong. Hong Kong University Press, xv + 234 pp.

HosONO, A., AND T. HiKiDA. 1999. Eumeces quadrilineatus (Asiatic four-lined
skink). Reproduction. Herpetological Review, in press.

Karsen, S., M. Lau, and A. Bogadek. 1986. Hong Kong Amphibians and Rep-
tiles. Hong Kong, Urban Council. 136 pp.

Kato, J., T. HiKiDA, A. Bogadek, M. Lau, and H. Ota. 1998. Karyotype of the
Chinese four-lined skink, Eumeces quadrilineatus (Reptilia: Scincidae) from
Hong Kong. Raffles Bulletin of Zoology, 46(1): 35-40.

Lazell, J. 1988. Soko Islands, South China Sea. Explorers Journal. 66(2): 80-
85.

Lazell, J., M. Lau, and W. Lu. 1997. A brief herpetological excursion to Wai
Ling Ding, Wanshan Islands, South China Sea. Asiatic Herpetological Re-
search, 7: 80-84.

Lazell, J., and W. Lu. 1999. Grayian distributions: The Chinese-American bio-
geographic connection, pp. 73-97. In X. Pang (ed.). Proceedings on Biodi-
versity of the Nanling National Nature Reserve. Guangzhou, China. Guang-
dong Scientific and Technology Press. 468 pp.

LiEB, C. S. 1985. Systematics and distribution of the skinks allied to Eumeces
tetragrammus (Sauria: Scincidae). Natural History Museum of Los Angeles
County Contributions in Science, 357: 1-19.

Pope, C. H. 1935. The reptiles of China. New York, American Museum of Natural
History, lii + 604 pp.

Taylor, E. H. 1935. A taxonomic study of the cosmopolitan scincoid lizards of
the genus Eumeces, with an account of the distribution and relationships of
its species. University of Kansas Science Bulletin, 24: 1-643.

Zhao, E., and K. Adler. 1993. Herpetology of China. Oxford, Ohio, Society for
the Study of Amphibians and Reptiles. 522 pp.