Ants of Tonga1 James K. Wetterer2 Abstract: This paper presents combined published, unpublished, and new ant records from 17 islands of Tonga representing all four island groups: Tongatapu (Tongatapu, ‘Eua, ‘Onevai, Pangaimotu), Ha‘apai (Lifuka, Kao, Tofua, ‘Uonu- kahahake, Nomuka, Nomuka-iki, Mango, Telekitonga), Vava‘u (Vava‘u, Nua- papu, Kapa), and the Niuas (Niuatoputapu, Niuafo‘ou). These records increase the list of ants known from Tonga to 53 species. Ten species, including six un- described species, are local endemics found only in Tonga or only in Tonga and Samoa: Adelomyrmex sp., Camponotus conicus, Camponotus nigrifrons, Hypoponera sp., Monomorium sp., Ochetellus sp., Pheidole sp., Pristomyrmex sp., Strumigenys zakharovi, and Vollenhovia samoensis. Another 21 species are broadly distributed Pacific natives: Anochetus graeffei, Camponotus chloroticus, Hypoponera confinis, Monomorium liliuokalanii, Monomorium talpa, Odontomachus simillimus, Oligo- myrmex atomus, Pheidole oceanica, Pheidole sexspinosa, Pheidole umbonata, Ponera incerta, Ponera tenuis, Pyramica dubia, Rogeria stigmatica, Solenopsis papuana, Stru- migenys godeffroyi, Tapinoma minutum, Technomyrmex albipes, Tetramorium in- solens, Tetramorium pacificum, and Tetramorium tonganum. Finally, 22 species are not native to the Pacific region, but were brought to the region by human com- merce: Anoplolepis gracilipes, Cardiocondyla emeryi, Cardiocondyla nuda, Hypoponera opaciceps, Hypoponera punctatissima, Monomorium floricola, Monomorium pharaonis, Monomorium sechellense, Paratrechina bourbonica, Paratrechina longicornis, Paratre- china vaga, Pheidole fervens, Pheidole megacephala, Plagiolepis alluaudi, Pyramica membranifera, Solenopsis geminata, Strumigenys emmae, Strumigenys rogeri, Tapi- noma melanocephalum, Tetramorium bicarinatum, Tetramorium lanuginosum, and Tetramorium simillimum. The number of ant species now known from Tonga is much as would be expected based on the species-area relationship for the neighboring island groups of Fiji, Wallis and Futuna, and Samoa. Differences in ant species richness among these island groups is primarily due to a greater number of local endemics in the island groups with greater land area. The Kingdom of Tonga consists of about 40 of the Tongan islands are inhabited year- 170 islands with a total land area of @700 round. km2 spread across 350,000 km2 of western Due to the difficulty and expense of travel Polynesia between 15–23 S and 173–177 to distant and unpopulated islands, most W. Tonga is divided into four major island Tongan ant records come from the three groups (from south to north): Tongatapu, largest and most accessible islands: Tonga- Ha‘apai, Vava‘u, and the Niuas. Only about tapu, ‘Eua, and Vava‘u. On these islands, hu- man activity has heavily impacted most flatter areas (Drake et al. 1996, Steadman and Frei- 1 feld 1998, Franklin et al. 1999). Tongatapu, Financial support was provided by Harvard Univer- 2 sity, Florida Atlantic University, and Edward O. Wilson. by far the largest island of Tonga (259 km ), Manuscript accepted 10 July 2001. makes up 37% of the total land area of the 2 Honors College, Florida Atlantic University, 5353 kingdom. Tongatapu is very flat, tilting only Parkside Drive, Jupiter, Florida 33458. slightly up to 30-m cliffs along the southern shore (maximum elevation, 82 m). About Pacific Science (2002), vol. 56, no. 2:125–135 two-thirds of Tonga’s 100,000 people live on : 2002 by University of Hawai‘i Press. Tongatapu. ‘Eua, also part of the Tongatapu All rights reserved group, is the third largest island (87 km2) and 125 (V7 15/3 14:08) UHP/U J-9577 Pacific, 56:2 AC:(1)1/3/2002 (0).3.05.05 Janson pp. 125–136 Ch02_P (p. 125) 126 PACIFIC SCIENCE . April 2002 eastern Polynesia (Niue, the Cook Islands, and French Polynesia combined) to the east (Taylor 1967, Wilson and Taylor 1967, Morrison 1996a,b, 1997). In this study, I in- crease the list of ants known from Tonga to 53 species. materials and methods In addition to published records of ants from Tonga, I searched for ant specimens from Tonga in the collections of several museums: the U.S. National Museum of Natural His- tory (usnm) in Washington, D.C.; the Amer- ican Museum of Natural History (amnh) in New York; the Museum of Comparative mcz Figure 1. Number of known ant species from Tonga in Zoology ( ) in Cambridge, Massachusetts; relation to total land area, compared with values for and the New Zealand Arthropod Collection Tonga from Wilson and Taylor (1967), and for sur- (nzac) in Auckland. rounding island groups. Also, from 16 to 31 August 1995, I col- lected ants on the three largest islands (Ton- gatapu, ‘Eua, and Vava‘u), plus Lifuka and the southernmost inhabited island of Tonga. Kapa. Lifuka, the administrative center of the ‘Eua rises gradually from west to east in a se- Ha‘apai island group, is small, flat (11 km2; ries of terraces up to a 250- to 300-m eastern maximum elevation, 14 m), and highly dis- ridge (maximum elevation, 328 m) and then turbed throughout. Kapa is a small island (6.4 drops steeply down to the east coast (Drake km2; maximum elevation, 96 m) in the Vava‘u et al. 1996). All people on ‘Eua live on the group. west side of the island, and the steep eastern I collected by visual search, turning over slope has much intact forest (Drake et al. rocks and logs, stripping the bark off logs, and 1996). Vava‘u, the second largest Tongan is- breaking logs apart, piece by piece. Many land (104 km2), is hilly. The highest points of areas throughout Tongatapu and western the island of Vava‘u are Mount Mo‘ungalafa ‘Eua had the exotic big-headed ant, Pheidole (204 m) and Mount Talau (130 m). On megacephala (Fabr.), under almost every rock Vava‘u there are many areas of forest at vari- and log and virtually no other ants. In con- ous stages of regeneration from agricultural trast, P. megacephala was much less common use (Steadman and Freifeld 1998, Franklin on Vava‘u and Kapa, and rare on Lifuka. The et al. 1999). primary objective of my collection was to The ant fauna of Tonga is a mix of native document as fully as possible the diversity of Pacific species and exotic ‘‘tramp’’ species. ants in Tonga. I therefore usually skipped Wilson and Taylor’s (1967) review of the ants over most areas with extremely high P. mega- of Polynesia reported 21 ant species from cephala density. Instead, I concentrated my Tonga. This is a low value compared with collecting efforts in relatively undisturbed records from the immediately surrounding forests that had few or no P. megacephala island groups (Figure 1): 88 ant species from present. I am currently preparing a more de- Fiji to the west (Wilson and Hunt 1967), 37 tailed, ecologically based account of these from Wallis and Futuna to the northwest collections, documenting the impact of P. (Wilson and Hunt 1967, Gutierrez 1981 in megacephala and other exotic ants in Tonga Jourdan 1997), 67 from Samoa to the north (unpubl. data). (Wilson and Hunt 1967, Wilson and Taylor I divided the Tongan ant species into three 1967; unpubl. data), and @50 from south- categories based on their distributions and (V7 15/3 14:08) UHP/U J-9577 Pacific, 56:2 AC:(1)1/3/2002 (0).3.05.05 Janson pp. 125–136 Ch02_P (p. 126) Ants of Tonga . Wetterer 127 presumed origins, following Wilson and Mayr (1870, 1876) listed 17 ant species Hunt (1967): (1) local endemics, found only from the ‘‘Tonga Islands’’ based on speci- in Tonga or only in Tonga and Samoa, (2) mens at the Godeffroy Museum in Hamburg, broadly distributed Pacific natives, found Germany. Mayr (1870, 1876) gave no collec- continuously from the Indo-Australian area tor information for any specimen, and listed into Polynesia, and (3) exotic ‘‘tramp’’ spe- Tongatapu Island as the collection site for cies, distributed in the Pacific by recent hu- two species. I have assumed, perhaps erro- man commerce. neously, that all of Mayr’s records came from Tongatapu (Tables 1–3). Wheeler (1935), results in his review of the ants of Oceania, listed 16 species from Tonga, identical to Mayr’s I found published and unpublished records of (1876) list except for the unexplained omis- ant species from numerous collections (Table sion of Tapinoma melanocephalum (Fabr.). 1) conducted on 17 Tongan islands repre- Wilson and Taylor (1967) reported rec- senting all four island groups: Tongatapu ords of 21 ant species from Tonga, including (Tongatapu, ‘Eua, ‘Onevai, Pangaimotu), Mayr’s (1876) records, plus new records from Ha‘apai (Lifuka, Kao, Tofua, ‘Uonukaha- three collectors: W. Cottrell-Darmer, G. P. hake, Nomuka, Nomuka-iki, Mango, Tele- Wilder, and N. L. H. Krauss (Tables 2 and kitonga), Vava‘u (Vava‘u, Nuapapu, Kapa), 3). Wilson and Taylor (1967) deleted one and the Niuas (Niuatoputapu, Niuafo‘ou). species from Mayr’s list: Camponotus rufifrons (Mayr). Although C. rufifrons is considered a valid Melanesian species (Bolton 1995), Wil- Published Ant Records son and Taylor (1967) concluded that the I found reliable published records of a total record of C. rufifrons from Tonga was a mis- of 49 ant species from Tonga (Tables 1–3; identification of C. conicus (Mayr). Mayr 1870, 1876, Wheeler 1935, Wilson Dlussky (1994a) listed ants collected dur- and Taylor 1967, Carver et al. 1993, Dlussky ing two visits to Tonga of the Soviet research 1994a,b, Swaney 1994, Zakharov 1994, Stech- ship Kallisto (Tables 2 and 3). In 1976–1977, mann et al. 1996). Y. I. Chernov collected ants on Niuafo‘ou in TABLE 1 Collection Dates and Locales for Ants from Tonga Collector (Source) Collection Date Island(s) a. Unlisted (Mayr 1870, 1876) <1870 T? b. Cottrell-Dormer (Wilson and Taylor 1967) <1914–<1935 T c. Wilder (Wilson and Taylor 1967) 1923–1925 T, V, ‘‘Ha‘apai’’ d.