Worker small, mouomorphic, with 4-jointed labial and 6-jointed maxillary palpi, multidenticulatc mandibles, 12-jointed antenna- and entire or medially more or less emarginate clypeus. The node is reduced to an anterior thickening of the depressed or flattened petiole which is overlain by the first gastric segment; anus usually inferior. Gizzard short, calyx usually not divided into distinct sepals, feebly convex, covered with fine hairs, with the bulb almost exposed when viewed from the side.

The female is usually considerably larger than the male. The anterior wings have a single cubital cell, rarely two, and the discoidal cell is often lacking.

The male is commonly as small as the worker and has well-developed denticulate mandibles. Antennae filiform, with long scape, usually surpassing the posterior border of the head and as long as the three first funicular joints together. Thorax stout; mesonotum not. overhanging the pronotum. Genital appendages voluminous, the stipes with a large squamula and its free portion of variable shape. Wings as in the female, but the discoidal cell is often lacking in the smaller species.

Colonies of Tapinoma are usually populous and live in the ground or in the cavities of plants. The workers are timid and emit from their anal glands a strong odor like that of rancid butter ('Tapinoma-odor"). The genus is cosmopolitan and in the Nearctic Region reaches to rather high latitudes and altitudes (Map 32). One of the species. Tapinoma melanocephalum , has been widely distributed by commerce throughout the tropics of both hemispheres. It is often a pest in shops and is known in Cuba as the "hormiga bottegaria."

T. melanocephalum (Fabricius) is an introduced species, not definitively established in the state. T. sessile (Say) is a very common ant, found in almost all habitats in California except deserts and areas invaded by Linepithema humile . T. sessile shows substantial variation in size and color. At scattered locations in California a bicolored (orange and black) form of T. sessile occurs sympatrically with the typical unicolored dark brown/black morph. Workers of intermediate color have also been observed, suggesting that the two forms are conspecific. An alternative interpretation is that there are two species which occasionally exchange genes, perhaps analogous to the situation between Forelius mccooki and F. pruinosus and between Dorymyrmex bicolor and D. insanus .

Species identification: key in Creighton (1950a). Additional references: Meissner and Silverman (2001), Smith (1965), Wang and Brook (1970).

Within the Dolichoderinae two genera, Tapinoma and Technomyrmex , are isolated in their female castes by the synapomorphic extreme reduction of the petiole and its accommodation in a longitudinal groove or impression in the ventral surface of the first gastral tergite, which overhangs and conceals the petiole in dorsal view when the mesosoma and gaster are aligned. The petiole is so reduced in these two genera that in profile there is no trace of a node or scale; at most there is a very short raised surface immediately behind the peduncle. The function of this raised surface is to provide an insertion-site for the exterior levator muscle of the petiole. Pseudaphomomyrmex exhibits these structures.

Technomyrmex and Tapinoma are separated in the female castes by the contrasting morphologies of their gastral apices. In Technomyrmex the sclerites of the gastral apex are unspecialised, except that the pygidium is small. Gastral tergite 5 is therefore in line with tergites 1 - 4 and as a result all five tergites are visible in dorsal view. In contrast the pygidium in Tapinoma is reflexed, the fifth tergite being folded back and down, below the fourth tergite, and is clearly visible in ventral view. Also in that view the fourth tergite frequently forms a distinct projecting rim above the reflexed fifth. In consequence only gastral tergites 1 - 4 are visible in dorsal view. Pseudaphomomyrmex exhibits the latter morphology, which is uniquely characteristic of Tapinoma , and thus the former name is relegated to the synonymy of the latter.

Tapinoma Foerster , 1850: 43. Type-species: Tapinoma collina Foerster , 1850: 43 [junior synonym of Formica erratica Latreille , 1798: 44], by monotypy.

Micromyrma Dufour , 1857: 60. Type-species: Micromyrma pygmaea Dufour , 1857: 61, by monotypy. [Synonymy by Mayr, 1863: 455, confirmed by Shattuck, 1992: 146.]

Semonius Forel , 1910b: 21. Type-species: Semonius schultzei Forel , 1910b: 21, by monotypy. [Synonymy by Shattuck, 1992: 146.]

Pseudaphomomyrmex Wheeler , 1920: 53. Type-species: Aphomyrmex emeryi Ashmead , 1905: 111, by original designation. Syn. n.

Zatapinoma Wheeler , 1928: 20. Type-species: Zatapinoma annandalei Wheeler , 1928: 20, by original designation. [Synonymy by Shattuck, 1992: 146.]

Neoclystopsenella Kurian , 1955: 133. Type-species: Neoclystopsenella luffae Kurian , 1955: 133, by monotypy. [Synonym by Brown, 1988: 337.]

Comments

1 At various times in its history Micromyrma has been regarded as a genus, a subgenus of Tapinoma and a junior synonym of Tapinoma . A short synopsis of the authors responsible for these opinions through time is presented in Bolton (2003). The two authors of synonymy given above are emphatically supported here.

2 Note that Tapinoptera Santschi (1925: 348), formerly regarded as a junior synonym of Tapinoma (e.g. Shattuck 1992: 146; Bolton 2003: 91) is now known to be a junior synonym of Technomyrmex Mayr , 1872, and will be dealt with in a forthcoming taxonomic revision of Technomyrmex by Bolton (in preparation). It has therefore been deleted from the taxonomic synopsis of Tapinoma .

Canindeyú (ALWC, IFML, INBP).

Tapinoma Forster , 1850, Hym. Stud. l:43 Aachen.

Type-species: Tapinoma dufouri Donisthorpe , 1943, Ann. Mag. Nat. Hist.(l 1)10:662.

Distribution: Palaearctic, Ethiopian, Oriental, Australian, Polynesian, Nearctic & Neotropical regions.

Formica , pt., Latr. Hist. Nat. Fourm. 182 (1802).

Tapinoma , Foerst. Hym. Stud. 43 (1850).

Ocelli obliterated in the workers, present in the males and females; the scale of the petiole flattened, decumbent, usually received into an impressed fovea at the base of the abdomen; the thorax deeply impressed between the meso- and metathorax, the latter obliquely truncated; wings as in the second division of Formica .

Palpi maxillares 6-articulati, labiales 4-articulati, dimidia longitudine priorum breviores. Antennae filiformes, infra medium faciei insertae; clypeus mediae magnitudinis, apice medio profunde exciso; squama abdominis segmenti primi oblonga, subrectangularis, depressa, foveola basali segmenti seeundi recepta, vix conspicua.