Striped Skinks in Oceania : The Status of Emoia caeruleocauda in Fiji

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. MATERIALS AND METHODS "caeruleocauda" skinks were believed to occur only on the western edge, no farther east than Vanuatu and the Carolines. In the late 1970s, Pernetta and Watling (1979) reported E. caeruleocauda from two Fijian islands (Taveuni, Viti Levu) and considered the species to be a Fijian native. Brown (1991) was able to examine only four specimens for his monograph of Emoia and suggested that the species was probably an exotic for Fiji. Zug (1991) found only one voucher (collected in 1911) in the museums of the world and similarly considered the Fijian population as an introduced one. This absence of vouchers stimulated our search for E. caeruleocauda in Fiji. We can now confirm Pernetta and Watling's report of a Taveuni population. There, E. caeruleocauda occurs abundantly in the native mountainside forest, suggesting that it is a native species. We examine this native versus exotic question further here through an analysis of scalation and morphometries. Our comparison examines four insular populations: Caroline Islands (Pohnpei), Fiji (Taveuni), New Guinea (Morobe Province), and Vanuatu (Efate). Voucher and locality data are available in the appendix. The Fiji sample is the newly found population; the Vanuatu sample is the nearest-neighbor population to Fiji; the Caro183 CURRENTLY, BIOLOGISTS recognize three striped Emoia from the oceanic islands of the southcentral Pacific: Emoia caeruleocauda, E. cyanura, and E. impar. All three commonly have a dark dorsal background with a light middorsal stripe from the tip of the nose to the base of the tail; a pair of light dorsolateral stripes from the side of the head to the base of the tail; and a blue or green tail in juveniles. All three taxa occur together on some islands and can be broadly sympatric, although each tends to dominate in a different microhabitat. Owing to this sympatry and their similar appearances, the assignment of specific names to populations of these three species has been haphazard and further confounded by a proliferation of names for different insular populations. Early in this century, workers (e.g., Sternfeld 1920, Burt and Burt 1932) recognized that the Pacific striped Emoia easily divided into two groups based on the number of subdigitallamellae. The "caeruleocauda" skinks have a moderate number of lamellae «50 beneath fourth toe), whereas the "cyanura" skinks have numerous lamellae (>55). Further, the "cyanura" skinks occur throughout the tropical Pacific, but the I Manuscript accepted 3 April 1996. 2 Department of Vertebrate Zoology, National Museum of Natural History, Washington, D.C. 20560. 3 Laboratoire des Reptiles et Amphibiens, Museum National d'Historie Naturelle, 25 rue Cuvier, 75005 Paris, France.