Anochetus

Brown, WL Jr.,, 1978, Contributions toward a reclassification of the Formicidae. Part VI. Ponerinae, tribe Ponerini, subtribe Odontomachiti. Section B. Genus Anochetus and bibliography., Studia Entomologica 20, pp. 549-638 : 550-555

Anochetus

> Anochetus Mayr, 1861 , Die Europäischen Formiciden, Wien, p. 53-54. Type species: Anochetus ghilianii = Odontomachus ghilianii Spinola, 1853 , monobasic.

Myrmecia Fabricius, 1805 , Systema Piezatorum, p. 423.

> Odontomachus , Illiger, 1807, Mag. Insectenk., 6: 194.> Odontomachus , F. Smith, 1858: 79.

> Odontomachus , Brown, 1973: 178, 183.

> Stenomyrmex Mayr, 1862: 711-712 . Type species: Stenomyrmex emarginatus = Myrmecia emarginata Fabricius , by designation of Emery, 1911: 110; also Wheeler, 1911: 173. New synonymy.

> Anochetus subgenus Stenomyrmex , Emery 1890: 63-65. - Emery, 1911: 110. - Wheeler, 1925: 8-10, key. - Kempf, 1964: 237-246, Brasil, key. Kempf, 1972, 20-22, catalog of species.

> Myrmapatetes Wheeler, 1929 b: 6 . Type species Myrmapatetes filicornis Wheeler , by original designation, monobasic. Synonymized by Brown, 1953: 2. [13]

> Anochetus , reviews and catalogs, etc., mostly regional: Emery, 1894: 185- 188, New World, key. - Forel, 1900: 58-63, India, Burma, Ceylon, key. - Bingham, 1903: 38-45, India, Burma, Ceylon, key. - Emery, 1911: 107-111, world catalog of species. - Arnold, 1915: 103-108, southern Africa, key; 1926: 214-218, southern Africa, supplement. - Wheeler,

1922a: 96-99, Congo; 1922c: 790-792, Africa, catalog of species; 1922:

1012-1013, Malagasy catalog of species. - Wilson, 1959: 502-510, Melanesia, key. - Kempf, 1972: 20-22, New World tropics, catalog of species.

Worker: Similar to Odontomachus and with the characters of subtribe Odontomachiti (see Part VI, Section A, p. 72-74); size small (TL 2,9 mm in A. pupulatus ) to moderately large (TL nearly 12 mm in A. inca ). Color usually dull; brown, blackish, red, or yellow, sometimes bicolored.

Cranium basically as in Odontomachus , but often shorter; always without the complex relief of the vertex in that genus, so that antennal fossa, ocular ridge, extraocular furrow and temporal prominence are all lacking, or at least poorly developed; median furrow replaced by a shallow and fairly broad posteromedian impression, more or less well developed in most species; nuchal carina rounded and continuous, or forming an obtuse, round-pointed V across the posterodorsal margin of the vertex, not forming an acute V on the midline; apophyseal lines not present on occipital face (see fig. 4, p. 94 of Section A). Eyes varying from large and with many fine facets to dot-like, with as few as 5 indistinct facets, each eye situated in a shallow, elliptical orbital fossa in the usual position for the subtribe, most apparent when the eye is small (fig. 11).

Mandibles linear, but varying from long and slender, with slender teeth in a series along the inner margins, as in A. horridus (fig. 9), to rather stumpy, thickened apicad, and armed only with the apical triad of stout teeth, in some small forms (fig. 13) such as A. subcoecus . Intercalary tooth of apical triad reduced to a small tubercle on the inside of the ventral apical tooth in a few species, or even obsolete. Under mouthparts much as in Odontomachus ; maxillary palpi apparently always 4-merous, rather short in most species; labial palpi short, 3- or 4-merous.

Trunk with well-marked promesonotal and mesometanotal sutures; metanotal spiracles present in many species, indistinct or absent in the smallest ones. Propodeum rounded into declivity, or biangulate, or bidentate according to the species. Petiolar node varying in the extreme among species, ranging from conical, with an acutely tapered apical spine ( A. gladiator ) to merely conical ( A. risii ) to erect barrel-shaped ( A. sedilloti ), thick bidentate ( A. faurei ), thin squamiform (axially compressed, A. katonae ), and so on, in all gradations. The squamiform nodes may be narrowly rounded at the apex in side view, or sharply cultrate, and in front view may have convexly rounded apical margins, or be truncate, emarginate or sharply bidentate.

Gaster ranging from compact to slender; first segment (postpetiole) large, and usually separated from second by a distinct constriction, which, however, is not developed in some species (e.g., emarginatus , gladiator , altisquamis ).

Legs with simple tarsal claws; apical spurs of tibiae 1, 2, 2 or 1, 1, 2 or 1, 1, 1 or 1, 0, 1; at least one spur on the hind tibiae always pectinate.

Sculpture varying from almost completely striate or rugose with gastric dorsum densely reticulate and opaque, to almost completely smooth and shining. The fanwise striation of the frons is present, at least in abbreviated form, in all known species. Mandibles, antennae and legs usually smooth or finely and densely punctulate.

Pilosity varies widely; erect hairs simple, usually fine, abundant on body and appendages, to very sparse and limited; the small cryptobiotic forms often have reclinate pubescence developed at the expense of longer standing pilosity.

Ergatoid: Fairly common, and may possibly be the only functional queen in some groups (e.g., emarginatus ). Like the corresponding worker, but often with 1 or 3 ocelli present; compound eyes usually larger; scutellum usually differentiated as a small, transversely elliptical sclerite.

Queen: With wings, or dealate, and the usual other differences from the worker; size only slightly larger in most species. Petiolar node often more strongly axially compressed. Eyes usually much larger than in the worker. Anal lobe of hind wing present in larger species, lost in some of the smaller ones.

Male: Habitus typical of small to medium-sized male Ponerini . Anochetus males are usually distinguished by their habitus, by large to very large compound eyes, and especially by the form of the petiolar node, which is usually a low, muted version of that of the female castes of the particular species. Most male nodes are either subconical or triangular in side view, the triangular ones being biangular above, often with the upper border weakly emarginate in front view; extreme forms are squamiform and apically emarginate.

The most remarkable thing about Anochetus males is the extreme variation of their terminaba from one species to the next. This is in contrast to

Odontomachus , in which the known males have very similar terminal structures, at least as seen in the undissected state. In Anochetus , all of the basic ponerine structures are usually present: pygidium (tergum VIII), hypopygium (sternum IX), cerci (on membranous segment X, the proctiger), and the parts of the genital capsule proper: parameres (gonocoxites), volsellae (with digitus and cuspis), and aedeagus (penis valves). All of these parts may vary strikingly among species, even species that seem closely related judging form worker-queen traits.

Unfortunately, males found associated in the nest with the female castes are known only for a minority of the species. Additional kinds of males are known from collections at light or by Malaise trap, but it has not yet been possible to link any of these securely to worker-based species. As it stands, 3 described species are based on single male holotypes: pangens and consultons from Sri Lanka, and filicornis from Larat Island off West Irian. Probably some or all of these belong to species described under different names from the worker caste, so that synonymy will eventually result from the correct association of the sexes.

The most primitive terminalia known appear to be those of A. isolatus (figs. 60, 61) from New Guinea; this has the pygidium drawn out into a stout, downcurved spine, and the hypopygium is a broad linguiform piece; the parameres are simple, with narrowly rounded apices. These conditions are as in Odontomachus , which can be regarded as either the sister-genus of Anochetus , or a line descended from such primitive Anochetus as A. isolatus or A. gladiator . These same traits are also found in the presumptive ancestral Ponerini (of subtribe Ponenti ). The most primitive Anochetus species on worker-queen characters is A. gladiator , but the gladiator male remains unknown.

From the condition of A. isolatus , one finds transitions to forms in which each paramere is constricted apicad into a ventrally-directed digitiform process ( A graeffei , fig. 77; A. consultons ; A. sedilloti ) that becomes separated from the main body of the paramere by a more or less complete and flexible suture, or in which the body divides into two lobes in a complex way ( chirichinii , figs. 56-59). The linguiform hypopygium tends to be narrowed, probably convergently, into a median, narrow, rodlike piece in some species of both Old World and New World groups, or, unexpectedly, into slender, bilaterally arranged, twin rods ( madaraszi , figs. 64, 65), or a deeply cleft plate ( chirichinii , fig. 58). In some New World species, the parameres develop fancy lobes, sometimes with grotesquely sculptured extremites (figs. 72, 73), but it is not completely certain that these are Anochetus .

Volsellae and aedeagus vary considerably also, although these variations do not show so well in undissected material, and they are not dealt with in detail here (figs, 75 and 76; 72 and 78).

Unassociated males representing about 10 different species have been reviewed for this work, but I believe that nothing is gained by assigning new names to undescribed forms, all of which will eventually be tied to their respective female castes. The rearing of live colonies or colony fragments of Anochetus is to be encouraged, for in this way we are most likely to make the necessary male-female associations.

Probably a knowledge of the male terminalia is needed to resolve completely the difficulties of species distinction existing in such complexes as those of A. inermis , A. mayri , A. traegaordhi and A. graeffei .

Distribution and Bionomics

There topics have been touched upon for Anochetus in the respective summaries for subtribe Odontomachiti (A 77-88; the A. inermis of p. 80 is assigned to A. simoni in the present section). Anochetus colonies of all groups appear to contain fewer (usually <100 adult) individuals than do those of Odontomachus , and this together with their usually smaller body size tends to adapt them to living in cryptic sites of low volume, such as are available in rotten twigs in humus or forest litter, crevices in bark or rotten logs, hollow twigs in trees, palm leaf-base interstices, or small excavations in the soil.

Compared to Odontomachus , then, Anochetus species tend to be «interstitial» and more specialized in their microhabitat selection and lifeways; their environment is coarse-grained. We should recognize, meanwhile, that many of the species forage rather widely for their size, and ground- or rotten wood-nesting species often can be found well above ground level on forest or savanna woodland tree trunks, but in most cases after dark (e.g., africanas). Other species (e.g., levaillanti ) may nest in the soil in arid areas, and forage over the ground surface near midday in only scanty shade. Probably, though, most species are nocturnal foragers.

Still other species, perhaps including emarginatus , pellucidus , fuliginosus and faurei , appear to be more or less arboreal nesters and foragers, though we have scanty, merely suggestive data on this point.

Anochetus species are all certainly predaceous; the natural extent of their feeding on honeydew and other sugar sources is totally unknown. The mechanism of their trap-mandible is similar to that of Odontomachus ( Marcus, 1944, 1945), and like that genus, they can «jump» backwards by snapping the jaw-apices against smooth, unyielding objects. As befits their prevailingly small body size, Anochetus species tend to respond to massive disturbances with lethisimulation rather than the aggressive biting and stinging reactions of Odontomachus . On the whole, Anochetus species are slower and more deliberate in their hunting behavior than are Odontomachus , and more often tend to employ waiting-and-ambush tactics in securing their prey. Nothing substantial is known about their possible prey specificity. In fact, the biology of Anochetus is a subject wide open to all kinds of investigation.

Anochetus ranges about as far south as Odontomachus in South America (to northern Argentina) and Australia (to arid inland parts of Victoria and southwestern Australia), but reaches farther south in South Africa (at least to Port Elizabeth in the eastern Cape Province). In the Northern Hemisphere, it gets to Morocco, Tunisia, and even the extreme southern point of Spain, beyond the range of Odontomachus , and in the Middle East, A. evansi occurs in Kurdistan, but, like Odontomachus , Anochetus is limited northward in India and Pakistan by the Himalayas and Pamirs. In China, Anochetus is still known only from Kwangtung and Hainan, in the far south, whereas Odontomachus monticola ranges far to the north, even beyond Peking. In the Pacific, A. graeffei is widespread, undoubtedly through the agency of human commerce, and it reaches central Polynesia and Micronesia with Odontomachus simillimus .

In North America, Anochetus fails to extend northward beyond tropical Mexico and the Bahamas, while Odontomachus reaches Arizona, central Texas and southern Georgia. The differences in distribution between these two genera indicate that Odontomachus does somewhat better than Anochetus at producing species that can penetrate colder climates, but that Anochetus may have the edge in evolving species adapted to aridity. Both genera, of course, are predominantly tropical and forest-inhabiting.