Pacific Science (1997), vol. 51, no. 2: 183-188 © 1997 by University of Hawai'i Press. All rights reserved Striped Skinks in Oceania: The Status of Emoia caeruleocauda in Fijil GEORGE R. Zu02 AND IVAN INEICH3 ABSTRACT: A rediscovered population of Emoia caeruleocauda from the Fiji Islands is compared with populations from Papua New Guinea, the Caroline Islands, and Vanuatu. Morphometrically, females from all populations are somewhat smaller than males, although males are significantly larger only in head length and width, and hindlimb length. Females and males do not appear dimorphic in scalation. Interpopulation comparison shows the populations to differ from one another in morphometry and scalation. In morphometry females and in scalation males and females of Fiji and Vanuatu and those of the Carolines and Papua are more similar to one another than each member of a pair is to members of the other pair. These patterns of variation suggest that the Fijian population of E. caeruleocauda is a native one and not introduced. CURRENTLY, BIOLOGISTS recognize three striped "caeruleocauda" skinks were believed to occur Emoia from the oceanic islands of the south­ only on the western edge, no farther east than central Pacific: Emoia caeruleocauda, E. cya­ Vanuatu and the Carolines. In the late 1970s, nura, and E. impar. All three commonly have a Pernetta and Watling (1979) reported E. caeru­ dark dorsal background with a light middorsal leocauda from two Fijian islands (Taveuni, Viti stripe from the tip of the nose to the base of the Levu) and considered the species to be a Fijian tail; a pair of light dorsolateral stripes from the native. Brown (1991) was able to examine only side of the head to the base of the tail; and a four specimens for his monograph of Emoia and blue or green tail in juveniles. All three taxa suggested that the species was probably an occur together on some islands and can be exotic for Fiji. Zug (1991) found only one broadly sympatric, although each tends to domi­ voucher (collected in 1911) in the museums of nate in a different microhabitat. Owing to this the world and similarly considered the Fijian sympatry and their similar appearances, the population as an introduced one. assignment of specific names to populations of This absence of vouchers stimulated our these three species has been haphazard and fur­ search for E. caeruleocauda in Fiji. We can now ther confounded by a proliferation of names for confirm Pernetta and Watling's report of a different insular populations. Taveuni population. There, E. caeruleocauda Early in this century, workers (e.g., Sternfeld occurs abundantly in the native mountainside 1920, Burt and Burt 1932) recognized that the forest, suggesting that it is a native species. We Pacific striped Emoia easily divided into two examine this native versus exotic question fur­ groups based on the number ofsubdigitallamel­ ther here through an analysis of scalation and lae. The "caeruleocauda" skinks have a moderate morphometries. number of lamellae «50 beneath fourth toe), whereas the "cyanura" skinks have numerous lamellae (>55). Further, the "cyanura" skinks MATERIALS AND METHODS occur throughout the tropical Pacific, but the Our comparison examines four insular popu­ lations: Caroline Islands (Pohnpei), Fiji I Manuscript accepted 3 April 1996. (Taveuni), New Guinea (Morobe Province), and 2 Department of Vertebrate Zoology, National Museum Vanuatu (Efate). Voucher and locality data are of Natural History, Washington, D.C. 20560. available in the appendix. The Fiji sample is the 3 Laboratoire des Reptiles et Amphibiens, Museum National d'Historie Naturelle, 25 rue Cuvier, 75005 Paris, newly found population; the Vanuatu sample is France. the nearest-neighbor population to Fiji; the Caro- 183 184 PACIFIC SCIENCE, Volume 51, April 1997 lines sample represents the werneri concept of the four samples. All samples have HindlL, E. caeruleocauda, used commonly from 1929 HeadL, and HeadW of the males averaging sig­ into the 1980s; and the New Guinea sample nificantly larger (P < 0.05) than those of the represents the caeruleocauda type concept females. In three samples (except Vanuatu), Nar­ although specimens are not from the type Eye and EyEar mean lengths are also signifi­ locality. cantly larger in males. The Vanuatu males have We recorded 10 morphometric and 10 scal­ significantly longer SnEye, which is also longer ation characters. These are as follows (recorded in males from the Carolines and New Guinea as in Zug [1991] unless noted otherwise): Mea­ samples. Males in these latter two samples also surements-EyEar, orbit to ear distance (ante­ have significantly wider Interorb. Covariance rior corner of eyelids to anteromedial edge of analysis with SVL as the covariate showed that ear opening); HeadL, head length; HeadW, head the adjusted means for these characters remain width; HindlL, hindlimb length; Interorb, inter­ significantly different (P < 0.05) between the orbital width (across top of head at suture of sexes; indeed the significance increases in the second and third supraciliaries); NarEye, naris­ adjusted means, with females proportionately orbit distance (naris to anterior corner of eye­ smaller in all the preceding morphometric lids); NeckL, neck length; SnEye, snout-orbit characters. distance (tip of snout to anterior corner or junc­ In scalation, no sexual dimorphism is appar­ tion of upper and lower eyelids); SVL, snout­ ent in the Fiji and New Guinea samples (Table vent length; TrunkL, trunk or body length; Scal­ 1). Males and females from Vanuatu show sig­ ation-BlwEye, supralabial scale lying below nificant difference means for number of SupCil center oforbit; Dorsal, number ofrows ofdorsal and Midb scales and for number ofEyelid scales scales between the parietals and base of tail, in the Caroline sample. Because of the absence includes nuchal scales; Eyelid, number of of concordance in these latter two samples and enlarged upper eyelid scales; ForefL, number of absence of any sexual differences in the Fiji digital lamellae beneath fourth digit of forefoot and New Guinea samples, we interpret the four (the first proximal lamella counted is the first significant results out of 44 comparisons as sto­ scale wider than long in contact with a large chastic events and not indicative of sexual lateral/dorsal digit scale on at least one side); dimorphism in our E. caeruleocauda samples. HindfL, number of digital lamellae beneath fourth digit of hindfoot; Inflab, number of Geographic Variation infralabial scales; Midbody, number of scales around midbody; Supcil, number of supraciliar­ Because of the sexual dimorphism of mensu­ ies; Suplab, number ofsupralabial scales; Supoc, ral characters, adult male and female samples number ofsupraocular scales. All measurements were examined separately. For scalation, the and counts were taken from the right side unless samples included both sexes and a few immature damaged; measurements to 0.1 mm recorded by individuals, because neither sex nor maturity dial calipers. All statistical analyses were per­ affects the number of scales in an individual formed on SYSTAT 5.03 (Wilkinson 1990); we or sample. used the Student's t-test to compare means and Analysis of variance (ANOVA) revealed sig­ the Bartlett's adjusted X2 to test for homogeneity nificant differences (F > 3.0; df = 3,32) among of variance. localities for all mensural characters in females, and significant differences (F > 3.0; df = 3, 20) for only HeadW, NeckL, SnEye, NarEye, and Interorb in males. The general pattern for RESULTS both sexes is that the Fiji and Vanuatu samples Sexual Dimorphism averaged somewhat larger than the Carolines and New Guinea samples. Adult female E. caeruleocauda are usually To determine whether the characters with sig­ somewhat smaller (SVL) on the average than nificant differences have any discriminatory adult males but not significantly so for any of content, we used principal components (PC) Emoia caeruleocauda in Fiji-ZuG AND INErcH 185 TABLE 1 SUMMARY STATISTICS FOR SCALATION IN Emoia caeruleocauda CAROLINES FIJI VANUATU NEW GUINEA CHARACTERS n 22 14 20 18 Supcil 9.0 ± 0.49 8.4 ± 0.63 8.2 ± 0.55 9.0 ± 0.34 8-10 8-10 7-9 8-10 Eyelid 10.2 ± 1.22 9.1 ± 1.35 9.2 ± 0.81 10.1 ± 1.08 8-13 7-12 8-11 9-13 Inflab 6.2 ± 0.40 6.4 ± 0.63 5.8 ± 0.37 6.1 ± 0.24 6-7 6-8 5-6 6-7 Dorsal 56.2 ± 0.92 57.7 ± 1.20 55.1 ± 1.43 55.8 ± 1.51 54-58 56-60 52-58 53-59 Midbody 30.0 ± 0.90 33.0 ± 1.41 31.1 ± 1.07 28.7 ± 0.96 28-32 31-36 29-33 28-30 FourtL 27.4 ± 0.87 26.3 ± 0.83 23.3 ± 1.38 23.9 ± 2.08 26-29 25-28 21-26 21-28 HindtL 40.0 ± 1.48 38.0 ± 2.48 35.2 ± 1.60 34.8 ± 2.71 37-42 33-41 32-38 30-39 NOTE: Character abbreviations are defined in the Materials and Methods section; values are mean:!: standard deviation and range. analysis to examine each sexual set by its "sig­ are Supcil, Eyelid, Inflab, Dorsal, Midbody, nificant" characters. In females, the first three ForetL, and HindtL. In general, the Fiji and components explained 83% of the total variance, Vanuatu samples averaged somewhat higher in and all characters except HindlL loaded heavily number of Midbody scales and lower in Supcil (0.67-0.95) in the first component. Only HindlL and Eyelid than the Caroline and New Guinea strongly influenced (0.93; others <0.38) the sec­ samples. In other characters, different associa­ ond component, and only TrunkL (-0.60) and tions exist; for example, lower Inflab, ForetL, SVL (-0040) weighed strongly on the third com­ and HindtL linked the Vanuatu and New Guinea ponent.