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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.