^o 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 c U\- r ""-•--"'' ""t;; ""^"•i 1 \f 5 J, y^ ^Sv/-'v-''Wyv ^-^,-^''^''^'' S(^ ~ r -^s 2 y^ (5 / x''^ — ^ 20»N- L 1 y ^A <^ 115°E 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 1> -c? f ^ 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 • 8- ■ • X © • {•J • • 7 0 © : • o • • • f : D i • • 2 • 6 ▲ • ▲ ▲ o ■: t? i o 5 o I' A 4 ■ • * •1 3 • ■'l ■^ F M A M O N 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. 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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.