Tetramorium lanuginosum

The wooly ant, Tetramorium lanuginosum MAYR 1870, has long been recognized as a widespread tramp species dispersed through human commerce. Based on its distribution and those of its closest known relatives, T. lanuginosum appears to be native to tropical and subtropical East Asia and perhaps also northern Australia and western Oceania. Tetramorium lanuginosum appears to be particularly common on small islands, possibly due to reduced competition with dominant ants in these habitats. Recent first records of T. lanuginosum on many islands of Samoa, the Galapagos, Madagascar (and neighboring island groups), and the West Indies suggest that exotic populations of T. lanuginosum are expanding on numerous tropical islands. Nonetheless, it appears unlikely that T. lanuginosum will ever become a significant exotic pest species, except perhaps on small tropical islands (from the abstract of Wetterer 2010).

Identification
Monomorphic robust ants with a slow and steady gait. Workers possess a thick coat of soft erect hairs, some of which are branched into two or three tips.

Distribution
Modified from Wetterer (2010): Tetramorium lanuginosum is widespread in tropical and subtropical parts of Asia, Australia, and Oceania. Outside of this region most records are concentrated in three areas: Madagascar and neighboring islands, the Galapagos, and the Eastern Caribbean. Records for these island groups are largely records from the past ten years (c. 2000-2010). Other more scattered reports including records from tropical Africa, the Mediterranean, Mexico, and the southeastern US, Northern Europe (three sites - Kew Gardens, the Birmingham Botanical Garden, and the Dudley Zoo) and one site in the Netherlands (an indoor record in Amsterdam; DE JONGE 1985).

It is believed Tetramorium lanuginosum is native to tropical Asia. The species occurs over a seemingly continuous range from India, through tropical and subtropical East Asia, to northern Australia, and thus is probably native to much of this region, and perhaps even to parts of western Oceania, e.g., the Solomon Islands, Palau, and the Mariana Islands. (Wetterer 2010)

Distribution based on Regional Taxon Lists
Afrotropical Region: Comoros. Australasian Region: Australia. Indo-Australian Region: American Samoa, Borneo, Fiji, Guam, Indonesia, Kiribati, Krakatau Islands, Marshall Islands, Micronesia (Federated States of), New Guinea, Philippines, Samoa, Singapore, Solomon Islands, Tokelau, Tonga, Wallis and Futuna Islands. Malagasy Region: Madagascar, Mauritius, Mayotte, Réunion, Seychelles. Nearctic Region: United States. Neotropical Region: Aruba, Barbados, Dominican Republic, Ecuador, Greater Antilles, Mexico, Puerto Rico. Oriental Region: Bangladesh, India, Myanmar, Thailand, Vietnam. Palaearctic Region: China, Iberian Peninsula, Israel, Japan, Malta, Spain.



Distribution records of Tetramorium lanuginosum as provided by James Wetterer, 2010.

Malagasy region
Hita Garcia and Fisher (2011 ) - In the Malagasy region T. lanuginosum is relatively widespread. The species can be found in many locations of Northern Madagascar and on most of its surrounding island systems, e.g. the Comoros, Mayotte, Mauritius, Seychelles, and Reunion. Wetterer (2010) points out that T. lanuginosum might have reached the Malagasy region recently because almost all records of the species are dated after 2001. We only tentatively agree with this point of view since T. mauricei, now a synonym of T. lanuginosum, was collected in 1942 from Mauritius and later described by Donisthorpe (1946). Another reason to be cautious is that most collecting in the Malagasy region has been performed in the last two decades; thus, large numbers of fresher specimens does not necessarily prove that the species was not abundant previously. Nevertheless, T. lanuginosum was not mentioned from Mauritius by Ward (1990) so it is possible tat the species was already present in the area but spread over the last one or two decades.

Nomenclature

 *  lanuginosum. Tetramorium lanuginosum Mayr, 1870b: 976 (w.) INDONESIA (Java). Viehmeyer, 1916a: 140 (q.); Imai, Baroni Urbani, et al. 1984: 8 (k.). Combination in Triglyphothrix: Emery, 1891b: 4 (footnote); in Tetramorium: Bolton, 1985: 247. Senior synonym of australis, ceramensis, felix, flavescens, laevidens, mauricei, orissana, striatidens, tricolor: Bolton, 1976: 350. See also: Hita Garcia & Fisher, 2011: 27.
 * striatidens. Tetramorium obesum r. striatidens Emery, 1889b: 501 (w.) MYANMAR. Wheeler, G.C. & Wheeler, J. 1973b: 78 (l.). Combination in Triglyphothrix: Emery, 1891b: 4. Raised to species: Forel, 1903a: 704. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * laevidens. Triglyphothrix striatidens var. laevidens Forel, 1900e: 284 (w.) MEXICO. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * australis. Triglyphothrix striatidens var. australis Forel, 1902h: 449 (w.q.) AUSTRALIA. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * orissana. Triglyphothrix striatidens r. orissana Forel, 1902c: 239 (w.) INDIA. Raised to species: Bingham, 1903: 174. Subspecies of striatidens: Emery, 1924d: 274. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * ceramensis. Triglyphothrix ceramensis Stitz, 1912: 506 (w.) INDONESIA (Seram I.). Junior synonym of lanuginosum: Bolton, 1976: 350.
 * felix. Triglyphothrix striatidens var. felix Forel, 1912k: 160 (w.) SEYCHELLES IS. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * flavescens. Triglyphothrix striatidens var. flavescens Wheeler, W.M. 1929g: 55 (w.) SINGAPORE. [Unresolved junior secondary homonym of flavescens Emery, above.] Junior synonym of lanuginosum: Bolton, 1976: 350.
 * mauricei. Triglyphothrix mauricei Donisthorpe, 1946c: 778 (w.) MAURITIUS. Junior synonym of lanuginosum: Bolton, 1976: 350.
 * tricolor. Triglyphothrix tricolor Donisthorpe, 1948g: 136 (w.q.) NEW GUINEA. Junior synonym of lanuginosum: Bolton, 1976: 350.

Worker
Hita Garcia and Fisher (2011 ) - HL 0.595–0.655 (0.626); HW 0.560–0.630 (0.590); SL 0.400–0.475 (0.438); EL 0.120–0.150 (0.137); PW 0.380–0.440 (0.418); WL 0.630–0.720 (0.683); PSL 0.155–0.205 (0.172); PTL 0.185–0.220 (0.200); PTH 0.190–0.215 (0.203); PTW 0.180–0.230 (0.210); PPL 0.170–0.215 (0.194); PPH 0.160–0.195 (0.179); PPW 0.190–0.230 (0.216); CI 92–98 (94); SI 71–76 (74); OI 21–25 (23); PSLI 25–31 (28); PeNI 47–54 (50); LPeI 93–105 (99); DpeI 97–110 (104); PpNI 48–55 (52); LPpI 100–116 (109); DPpI 105–121 (111); PPI 98–110 (103) (20 measured).

Head longer than wide (CI 92–98). Anterior clypeal margin with small but distinct median impression. Frontal carinae strongly developed, curving down ventrally between posterior eye level and posterior margin of head to form posterior and ventral margins of antennal scrobe. Antennal scrobes well-developed and broad, usually with distinct margin all around. Antennal scapes relatively short, fitting well within antennal scrobe (SI 71–76). Eyes of moderate size (OI 21–25), with 8 to 10 ommatidia in longest row. Mesosoma convex in profile, sides rounding smoothly onto dorsum. Metanotal groove absent. Propodeal spines medium-sized to long and spinose (PSLI 25-31). Propodeal lobes small, triangular, and acute. Node of petiole rounded nodiform in profile, anterodorsal angle well-defined but not sharply angulate, situated much higher than rounded posterodorsal angle, causing dorsum to taper backward to posterior face; in dorsal view roughly as long as wide to weakly wider than long (DPeI 97–110), in lateral view roughly as long as high (LPeI 93–105). Postpetiole in lateral view rounded and much less voluminous than petiolar node, usually weakly longer than high (LPpI 100–116); in dorsal view postpetiole roughly as wide to weakly wider than petiole (PPI 98–110), and weakly wider than long (DPpI 105–121). Mandibles generally longitudinally striate, sometimes weakly developed. Clypeus usually longitudinally rugose, median ruga always developed with 1 to 2 weaker rugae at each side. Head reticulate-rugose, cephalic dorsum between frontal carinae dorsally more reticulate, close to the posterior clypeal margin often more longitudinally rugose. Ground sculpturation generally very weak to absent. Mesosoma and waist segments also reticulate-rugose, without any conspicuous ground sculpture. Gaster completely unsculptured, smooth, and shiny. Body pilosity usually very dense and relatively long but variable, generally all dorsal surfaces of head, mesosoma, waist segments, and gaster with numerous long bifid and simple hairs, usually a mixture of both present with either bifid or simple pilosity predominant, but both types always present; rarely some trifid hairs also present, though almost never on first gastral tergite. Variation in pilosity often observable within same series from same collection event. Frontal carinae and leading edges of antennal scapes with elongate, simple, standing hairs. Tibiae with relatively long suberect to erect standing hairs. Colouration variable, light brown to dark brown, gaster often darker than remaining body.

Type Material
Hita Garcia and Fisher (2011 ):

Holotype worker, INDONESIA, Java, Batavia [examined].

Tetramorium obesum r. striatidens Emery, 1889:501. Syntype workers, BURMA, Bhamo, VII.1886 (L. Fea) [examined].

Triglyphothrix striatidens var. laevidens Forel, 1900:284. Syntype workers, MEXICO (MHNG) [examined].

Triglyphothrix striatidens r. australis Forel, 1902a:449. Syntype workers, queens, AUSTRALIA, Queensland, Mackay (Turner) (MHNG; ) [partly examined].

Triglyphothrix striatidens r. orissana Forel, 1902b:239. Syntype workers, INDIA, Orissa (Taylor) (MHNG) [examined].

Triglyphothrix striatidens var. felix Forel, 1912:160. Syntype workers, SEYCHELLES, Felicite, Silhoutte, Mare aux Cochons, 1908 (H. Scott) (MHNG; ) [examined].

Triglyphothrix ceramensis Stitz, 1912:506. Holotype worker, INDONESIA, Seram Island (holotype location unknown).

Triglyphothrix striatidens var. flavescens Wheeler, W.M., 1929:55. Syntype workers, SINGAPORE, Johore, 2.II.1925 (F. Silvestri) (MCZ) [not examined].

Triglyphothrix mauricei Donisthorpe, 1946:778. Holotype worker, MAURITIUS, Rose Hill, 1942 (R. Mamet) (BMNH) [examined].

Triglyphothrix tricolor Donisthorpe 1948:136. Paratype workers, queens, NEW GUINEA, Maffin Bay, 17. & 20.VI.1944 (E.S. Ross) (BMNH, ) [examined].

Additional References

 * Hita Garcia, F. and B.L Fisher. 2011. The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region—introduction, definition of species groups, and revision of the T. bicarinatum, T. obesum, T. sericeiventre and T. tosii species groups. Zootaxa 3039:1-72.


 * Wetterer, J.K. 2010. Worldwide spread of the wooly ant, Tetramorium lanuginosum (Hymenoptera: Formicidae). Myrmecological News 13: 81-88.