Technomyrmex difficilis , Bolton, B., 2007

Bolton, B., 2007, Taxonomy of the dolichoderine ant genus Technomyrmex Mayr (Hymenoptera: Formicidae) based on the worker caste., Contributions of the American Entomological Institute 35, pp. 1-149: 47-50

publication ID

21343

persistent identifier

http://treatment.plazi.org/id/D23AC808-A5FF-EF08-42A2-255C95FE8F2D

treatment provided by

Donat

scientific name

Technomyrmex difficilis
status

stat. n.

Technomyrmex difficilis  HNS  Forel stat. n.

(Fig. 3)

Technomyrmex mayri r. difficilis  HNS  Forel, 1892: 242. Syntype workers and queen, MADAGASCAR: Nosibe, Village de l'Imerina (Sikora) (MHNG) [examined].

Technomyrmex mayri st. nitidulans  HNS  Santschi, 1930a: 72, figs 31 - 33. Syntype workers, MADAGASCAR: Nosi-b� (Decarpentries) (NHMB) [examined], Syn. n.

WORKER. Measurements: TL 2.4 - 3.1, HL 0.57 - 0.76, HW 0.52 - 0.69, SL 0.52 - 0.74, PW 0.36 - 0.47, WL 0.74 - 1.02 (35 measured). Indices: CI 89 - 97, SI 95 - 107, OI 25 - 30, EPI 72 - 86, DTI 127 - 135.

Frontal carina with 2 (very rarely 3) setae: in profile the first above the torulus, the second at about the level of the anterior margin of the eye; when a third seta present it is between these two. Dorsum of head posterior to this with a single pair of setae, in profile located just over half way between level of posterior margin of eye and posterior margin of head, not at the posterior margin; this pair of setae distinctly shorter than the posteriormost seta on the frontal carina (see notes below). Anterior clypeal margin with a very weak, shallow median indentation. With head in full-face view the sides shallowly convex and the posterior margin with a small shallow indentation medially. Eyes located in front of midlength, EPI <90; outer margin of eye breaks the outline of the side. Number of setal pairs on mesosoma: pronotum 1 - 2; mesonotum 0 - 1 (usually 1); propodeal dorsum 0; lateral margins of propodeal declivity 1 - 2, above the level of the spiracle. With mesosoma in profile the mesonotal outline is evenly curved, without a distinct step or angle in the outline that defines conspicuous dorsal and declivitous faces. Dorsum of propodeum short in profile and meeting the declivity in an angle; length of dorsum less than depth of declivity to spiracle. In dorsal view the metathoracic spiracles are very close to, or abut, the metanotal groove. Gastral tergites 1 - 4 each with numerous setae, distributed everywhere on the sclerites; maximum length of setae on first gastral tergite is usually slightly less than the maximum diameter of the eye but sometimes the two are subequal. Head, mesosoma, petiole and gaster dark brown to black; in profile the gaster may be slightly lighter than the mesosoma. Coxae, femora and tibiae the same colour as the mesosoma or slightly lighter; never with strongly contrasting lighter coxae. Tarsi of middle and hind legs yellowish white to yellow, distinctly paler than the tibiae.

Closely related to albipes  HNS  but separated by the presence of setae on the dorsum of the head behind the level of the posterior margin of the eye (never developed in albipes  HNS  ) and by having the promesonotum somewhat longer and more slender, DTI 127 - 135 (as opposed to DTI 110 - 124 in albipes  HNS  ). This species has been confused many times with albipes  HNS  , and isolated specimens with the characteristic cephalic setae abraded away are difficult to identify. In such specimens the eye may give a clue to the correct identity because in general, with the head in full-face view the eye in albipes  HNS  workers is flatter and less convex than in difficilis  HNS  so that the outer margin usually just fails to break the outline of the side of the head in the former but distinctly interrupts the outline of the side in the latter. There is some variation of this feature in both species. Additionally, the mesonotum generally has a pair of setae present in difficilis  HNS  whereas mesonotal setae are generally absent in albipes  HNS  . Again this character is variable because difficilis  HNS  samples are known where mesonotal setae are lacking and albipes  HNS  samples are known in which a pair is present.

Of all the material examined a few specimens from Madagascar and one specimen from U.S.A. had an extra pair of short setae on the dorsum of the head, behind the universally present pair. Whether these are genuine workers or the most worker - like form of intercaste remains to be seen. These individuals may resemble pallipes  HNS  in this character but samples of the latter always have the middle and hind femora and tibiae distinctly lighter in colour than the mesosoma and do not have tarsi that are much paler than the tibiae. Malagasy material of difficilis  HNS  tends to differ slightly from that of the rest of the world. The cuticle of the head and mesosoma is somewhat more glossy, the angle through which the propodeal dorsum meets the declivity is blunter and setae on the first gastral tergite are snorter. These differences seem consistently to isolate the Malagasy population, but at present I am not convinced that they are sufficient to justify separation at species - rank

T. difficilis  HNS  was originally described as a race of mayri  HNS  , but the two are quite different. T. difficilis  HNS  is a smaller species with shorter scapes, relatively larger eyes and a shorter, more compact mesosoma (compare measurements and indices). In addition, the metathoracic spiracles of mayri  HNS  , in dorsal view, do not abut the metanotal groove, and the propodeal dorsum is longer, its straight - line length in profile is greater than the depth of the declivity to the spiracle. Finally, the propodeal declivity of mayri  HNS  does not have setae that arise above the level of the spiracle whereas such setae are always present in difficilis  HNS  .

Worker - queen intercastes are produced in difficilis  HNS  , and according to Warner (2003, unpublished thesis) these may make up nearly half the colony. Intercastes have reproductive functions and are not usually found outside of nests; foraging behaviour appears to lie strictly in the domain of true workers. As is known in several other species of the albipes  HNS  group ergatoid males, as well as the usual alates, are produced by difficilis  HNS  . The alate males mate with alate queens in the usual nuptial flight, which initiates new nests. The queens of these colonies eventually die off and are replaced by reproductive worker - queen intercastes, all grades of which have spermathecae (absent from true workers) and they mate with ergatoid males. Nests in this condition then multiply by fission and produce polydomous colonies that are later able to produce new generations of alate queens and males.

In recent synoptic works on the Australian ant fauna that mention albipes  HNS  , that of Shattuck (1999) is most probably difficilis  HNS  , and the unnamed species of Andersen (2000) is certainly difficilis  HNS  as his figure 29 has the right proportions and clearly shows the posteriorly placed pair of setae on the head. T. difficilis  HNS  has also successfully colonised the state of Florida, U.S.A., where it was first described, as albipes  HNS  , by Deyrup (1991) and later included under that name by Vail, Davis, et al. (1994) and Deyrup, Davis & Cover (2000). It also seems probable that a proportion of the material listed as albipes  HNS  by Wilson & Taylor (1967) will be difficilis  HNS  .

In his unpublished thesis Warner (2003) succinctly summarises the nature of difficilis  HNS  (misidentified as albipes  HNS  in the study) as an invasive in Florida, U.S.A. He says that it "nests at or above ground level in numerous locations within the landscape, home and suburban woodland habitats. Nests are frequently found in trees and bushes, tree holes, under palm fronds and old petiole bases, under leaves on trees, in loose mulch, under debris, in leaf - litter, both on the ground and in rain gutters, wall voids, and attics. Nests tend to be found outside of structures more than inside." He points out that its main foods are plant nectar and honeydew but that the ants will also feed on dead insects and other protein. In houses they forage most commonly in kitchens and bathrooms, the best sources of food and water, as well as on exterior structures. Like some other species in the group (e.g. pallipes  HNS  , jocosus  HNS  ) they have been found nesting in electrical fixtures. Outdoors, workers of this species are most commonly encountered on vegetation although, like most or maybe all other species in the albipes  HNS  group, they also nest and forage terrestrially.

MATERIAL EXAMINED

Vietnam: Cam Ranh Bay, Kan Hoa Prov. (T.R. Taylor). Thailand: NE region, Chi Riv., Kalasin (K. Ogata). Malaysia: Negeri Sembilan, Pasoh For. Res. (Lewis & Jackson); Sabah, Tawau (M. Pfeiffer). Singapore: Kent Ridge (P.S. Ward); Botanic Gdns (Csiki); no loc. (Bir�). Indonesia: Flores, Manggarai Dist., Golo Leleng (M.I. Wibara); Krakatau Is, Panjang I. (K. Ogata). Philippines: Luzon, Benguet, Baguio (S. Sch�dl); Luzon, Batangas, 7 km S Lian (C.K. Starr); Luzon, Camarines Sur, Pili (C.K. Starr); Bukidnon, Musuan Maramag (Starr & Pinto); Surigao del N., Bayagnan I. (S. Sch�dl). Papua New Guinea: Wau (P.S.Ward). Australia: Northern Territory, Stapleton (G.F. Hill); NT, Berrimah (R. R. Snelling); NT, Sawcut Gorge (Taylor & Feehan); NT, Black Point, Coburg Pen. (T.A. Weir); Queensland, Torres Strait, Wyer I. (H. Heatwole); Torres Strait, Murray I., Maeri (H. Heatwole); Queensland, 1 km NW Cape Tribulation (A.L. Wild); Qld, ENE Mt Tozer (J.C. Cardale); Qld, W of Cooktown (J.E. Feehan); Old, Hinchinbrook I. Gayundah Ck (Monteith, Davies, Thompson & Gallon); Qld, 13 km WNW Lockhart River (A.L. Wild); Qld, 10 km NW Lockhart Riv. (P.S. Ward); Qld, 10 km NW Lockhart Riv. (A.L. Wild); Qld., Rounded Hill (I.D. Naumann). Marianas Is.: Guam I., Lamlam (N.L.H. Krauss); Guam I., Mt Alifan (N.L.H. Krauss). Micronesia: Caroline Is, Truk Is, Fefan I., Mt Iron (J.L. Gressitt). Madagascar: Prov. Antananarivo, Res. Ambohitantely, NE Ankazobe (Rabeson et al.); Antananarivo, NE Andranomay (Fisher et al.); Prov. Antsiranana, For. Antsahabe, W. Daraina (Fisher at al.); Antsiranana, Ampasindava, Ambilanivy (Fisher et al.); Antsiranana, Res. Spec. Ankarana, SSW Anivorano - Nord (Fisher et al.); Antsiranana, Res. Analamerana, Anivorano - Nord (B.L Fisher); Antsiranana, For. Binara, SW Daraina (Fisher et al.); Antsiranana, For. Ambato, Ambanja (B.L. Fisher); Antsiranana, P.N. Montaigne d'Ambre (R. Harin'Hala); Antsiranana, N Joffreville (R. Harin'Hala); Antsiranana, Sakalava Beach (R.

Harin'Hala); W Sakalava Beach (Schlinger et al.); Antsiranana, Montaigne Fran�ais (R. Harin'Hala); Antsiranana, For. Anabohazo, WSW Maromandia (Fisher et al); Antsiranana, R.S. Manongarivo, SW Antanambao (B.L. Fisher); Prov. Fianarantsoa, For. Atsirakambiaty, WNW Itremo (Fisher et al.); Fianarantsoa, P.N. Isalo, Ambovo Springs, N Ranohira (Fisher et al.); Prov. Mahajanga, P.N. Ankarafantsika, Ankoririka (E. Rabeson); P.N. Ankarafantsika, Tsimaloto (Rabeson et al.); P.N. Ankarafantsika, Ampijoroa (Rabeson et al); P.N. Ampijoroa (Rin'Ha & Irwin); P.N. Ankarafantsika, Ampijoroa (Fisher et al.); Mahajanga, P.N. Tsingy de Bemaraha, E. Bekopaka (Fisher et al.); P.N. Tsingy de Bemaraha, ESE Antsalova (Fisher et al.); Mahajanga, Res. Bemarivo, SW Besalampy (Fisher et al.); Mahajanga, P.N. Namoroka, NW and WNW Vilanandro (Fisher et al.); Mahajanga, Mahavavy Riv., SE Mitsinjo (Fisher et al); Mahajanga, For. Ambohimanga (Fisher et al.); Prov. Toliara, S.F. Mandena, NNE Tolagnaro (B.L. Fisher); Nosibe, Village de l'Imerina (Sikora); Nosi-b� (Decarpentries); 25 km. NNE Ankazobe (P.S. Ward); Station Foresti�re Ampijoroa (P.S. Ward); Res. Ankarana, SE Matsaborimanga (P.S. Ward). U.S.A.: Florida, Broward Co., Plantation (R. Scheffren); FL, Broward Co., Fort Lauderdale (J. Warner); FL, Brevard Co., Palm Bay (2. Prusak); FL, Sarasota Co., Myakka River State P. (J. Longino); FL, Jupiter U.K. Wetterer); FL, Juno (J.K. Wetterer); Washington, King Co., Seattle Woodland Park Zoo, tropical house (J. Longino). Puerto Rico: San Juan, Park Luis Mu�ez Marin (J.K. Wetterer).