Syscia augustae

This blind, subterranean predator is most commonly found in forests, usually in mesic areas. Nests are unorganized and individuals are found in the litter and under stones, or in branches embedded in soil in moist habitats. These ants are rarely collected and are usually accidentally found when one is excavating the nest of another species (Mackay and Mackay 2002).

Distribution
USA: AZ, TX; NM: we have no records, but it may occur in the state; Mexico: Nuevo Leon.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.



Biology
Wheeler (1902) - The Cerapachys nest was found about six inches below the surface soil under a layer of large flakes of limestone in the shade of some hackberry trees growing on the banks of Waller Creek. At first only six workers and the queen were taken, but on the following day Miss Rucker and myself succeeded in unearthing four more workers on the same spot. The whole nest could not have contained much more than a dozen specimens. Unfortunately there were no larvae or pupa. When first seen the Cerapachys were engaged in a battle with some much smaller subterranean ants (Ponera trigona var. opacior) which seemed to be invading the nest. The new species was slow in its movements as would be expected in creatures with such long bodies and short legs. They did not “feign death” when roughly handled, though some of them, when held in the forceps, remained motionless in the attitude probably assumed when they are being deported by their sister workers. While creeping about the ants carried their very robust antenna: in a peculiar manner. The scape was held erect or inclined forwards, but hardly in a horizontal or lateral position as in other ants, while the funicle could be folded down onto the front surface of the scape a little obliquely to the side. The habits, so far as these could be inferred from the little I saw of the ants in a living condition, recalled those of Stigmatomma pallipes described in a former paper (’00). As the workers are quite blind it seems probable that the species leads a subterranean life, seeking its prey in the soil or under the dead leaves. This seems also to be indicated by the depth at which these small insects were found. The very robust antennae and the beautifully developed stridulatory apparatus, which occupies the whole of the large membrane between the postpetiolar and first gastric segment, indicate that the senses of contact-odor and hearing are highly developed and may adequately compensate for the absence of visual organs.

On the 22nd of May, Mr. C. T. Brues found a solitary worker of the same Cerapachys under a stone at Pease Park, about two miles from the locality in which the species was first taken. That the insect is extremely rare is shown by the fact that it had not been found before during three years of careful collecting in the vicinity of Austin.

Wheeler collected a colony that he subsequently observed in a laboratory nest. He noted (Wheeler 1903): The colony of C. augustae, on which the following observations were made, was discovered May 6th, 1903, near high water mark in the bottom of Shoal Creek at Austin, Texas. It was inhabiting a simple, straight gallery about 5 cm. long by 7 mm. in diameter, under the very center of a large block of limestone. At one end the gallery dipped down into the soil to a depth of 4 cm. The ants, 29 in number, were all congregated in the surface gallery with their long bodies wrapped about a large packet of eggs. Only workers were found, though careful search was made for the peculiar wingless female described in my former paper. The whole colony, with the possible exception of a few ants that may have been out foraging, was captured and placed in a small Petri dish, the bottom of which had been provided with a thin layer of damp soil partly covered with a glass microscope slide. The ants soon took up their abode under the slide after collecting their scattered eggs. Nymphs of two common Texan termites (Amitermes tubiformans and Eutermes cinereus) were cut into a few pieces and given them as food. Even when these were placed only a few millimeters from the ants, the latter showed no signs of noticing them till they were actually touched with the antennae. And even then the ants often hesitated before attacking the still struggling heads and thoraces. Eventually the termites were dispatched by the ants curling about them and using both mandibles and sting. The latter produced sudden paralysis. Then the ants eagerly lapped up the juices exuding from the cut ends of the termite fragments, while remaining very quiet as if absorbed in the delight of feeding. The mandibles seemed to be too feeble to cut or puncture even so thin a chitinous investment as that of the termites.

The antennae are undoubtedly the most important and remarkable organs of Cerapachys. This is shown by their great thickness (whence the name of the genus), the differentiation of the glandiform terminal joint of the flagellum, and their singular freedom of movement. This freedom is permitted by the clypeus which is much compressed laterally in the form of a vertical crest, and does not overlap the scapes on the sides. The antennae are, in fact, kept in continual vibration in a plane perpendicular to the head with their elbows uppermost and not directed sidewise as in other ants, while the glandiform joint of the flagellum plays over the surfaces with which it comes in contact. The insects must be guided almost exclusively by the contact-odor sense in these organs since they have no trace of eyes. Pronounced negative heliotaxis, evidently depending on some photodermatic sense was apparent when the ants were exposed to the sun, though they did not respond very readily to the lower intensities of diffuse day-light. Strangely enough, this negative heliotaxis was not associated with a high degree of positive thigmotaxis, as it is in many other insects, since the animals showed no decided tendency to conceal themselves with their bodies applied to the earth or glass. Often the whole colony would lie exposed for hours on the surface of the soil, merely agglomerated in a mass about their eggs.

As the number of eggs visibly increased during the confinement of the colony, it is clear that some of these must have been laid by the workers, as there was no female in the nest. No ants could be more careful of their eggs. They enveloped them with their bodies so that the packet could not be seen except by disturbing the whole colony. When the packet was broken apart the eggs were eagerly sought and deftly brought together again. This brooding over the eggs is quite unlike anything I have seen in other ants except Eciton, the smaller species of which (E. opacithorax, schmitti, sumichrasti, etc.) have a very similar habit. Besides affording protection to the eggs, it may, perhaps, serve to hasten the embryonic development. The eggs are very slender (Figure, a), being fully four times as long as broad. They are not kept in several packets with the long axis of the component eggs parallel with one another, as in some Ponerinae (Leptogenys, Pachycondyla), but without any definite orientation in a single subspherical mass. The first eggs did not hatch till May 14th, showing that the incubation period must exceed eight days. They hatched rather slowly, a few at a time.

The larvae (Figure, b) were extremely slender, not twice as broad behind as at the anterior end, with well-marked segmental constrictions. The head is proportionately large, with strong, acute mandibles projecting beyond the clypeal and labial regions. The maxillae are furnished with a pair of prominent sensory papillae and the labium with a well-developed duct to the spinning glands. The dorsal surface of the head as well as the whole surface of the body is covered uniformly with short, slightly curved hairs. There are no traces of tubercles of any description. Attempts to observe the method employed by the ants in feeding their larvae were unsuccessful. Once, on placing a number of eggs and young larvae of Camponotus festinatus in the nest, I saw the young Cerapachys larvae feeding on the former after they had been carried under the slide by the workers. It was apparent also that the ants and their older larvae soon began to feed on the unhatched eggs and younger larvae of their own species, for the number of progeny decreased rapidly from day to day. In order to reduce the size of the colony and thus save as many of the young as possible from destruction, I killed and removed twelve of the workers May I7th. I was not successful, however, in stopping the infanticides, so on the following day I removed six more workers. By this time, however, though I had provided the nest daily with fresh termite food (the ants would not eat sweets, larvae of other ants, or miscellaneous insects) the Cerapachys became so demoralized that by May 9th no eggs and only five half-grown larvae remained. These larvae were carried by the ants after the manner of Eciton and Leptogenys, i. e. by the neck, with the long slender body extending back between the legs of the worker. The ants were quite as careful of their larvae as of their eggs.

To my intense disappointment, it soon became manifest that I should be unable to rear the few remaining larvae to the pupal stage. I therefore killed the surviving workers and the three larvae still uneaten May 20th. Thus I was unable to settle two important questions: first, the method of feeding the larvae, whether by regurgitation or with pieces of insect food; and, second, the character of the pupa, whether naked or covered with a cocoon. The powerful development of the larval jaws would seem to indicate that the young are fed with pieces of insect food, and from the fact that the larval spinning glands seem to be well developed, one may infer that the pupa is enclosed in a cocoon. Whoever is so fortunate as to happen on a colony of these ants during the middle or latter part of June will probably be able to determine the pupal characters without difficulty, as the pupae should at that time be found in the nests.

Nomenclature

 *  augustae. Cerapachys (Parasyscia) augustae Wheeler, W.M. 1902d: 182, figs. 1, 2 (w.q.) U.S.A. Wheeler, W.M. 1903g: 206 (l.); Wheeler, G.C. 1950: 106 (l.); Smith, M.R. 1942b: 63 (m.).

Worker
Length 2.5-3.5 mm. Head longer than broad, marginate and broadly excised behind and produced posteroinferiorly to form two acute. somewhat divergent angles, so that the head resembles in shape that of Eciton schmitti Emery. These posterior angles are continued downwards on either side as a fold which meets its fellow from the opposite side on the lower posterior surface of the head. Sides of head faintly and evenly convex; eyes entirely absent; lateral carina; well-developed; frontal carinae high, projecting, closely approximated, extending a short distance back between the antennal fovea; and ending on either side in a distinct tooth just in front of the rather pronounced frontal depression. Mandibles triangular, curved downwards at their tips, with distinctly crenated edges to their blades. Antennal scape somewhat more than half the length of the head exclusive of the mandibles, rapidly incrassated towards its apex, which is provided with a deep concavity on the anterior lateral surface for the insertion of the funicle; funicle 10-jointed; first joint longer than broad, almost concealed in the concavity of the scape; joints 2-9 distinctly broader than long, gradually increasing in size distally, terminal joint very large, glandiform; constituting a club which is as long as the five preceding joints of the funicle. Thorax cylindrical, fully two and one half times as long as broad, oblong when seen from above, dorsal surface flattened, mesoepinotal suture hardly indicated by a faint constriction. Posterior surface of epinotum abruptly declivous, carinate on either side and with an indistinct tooth above. Petiole subcuboidal, a little longer than broad, with flat dorsal surface; lower surface produced anteriorly into a large, compressed, plowshare like tooth. Postpetiole flattened dorsally, one and a half times as long as the petiole; when seen from above its anterior margin is hardly broader than the petiole, but its posterior border is half again as wide; its lower surface is convex and projects forward a little in front of the anterior dorsal border. Stridulatory organ highly developed, occupying the whole of the intersegmental membrane between the postpetiole and gaster. First gastric segment cylindrical, flattened on its dorsal surface, fully one and a half times as long as the postpetiole, slightly wider behind than in front. Remaining gastric segments very short, forming a rapidly declivous termination to the abdomen; second, third and fourth gastric segments of about equal length, tergite of the fifth segment triangular, covered with small but distinct spines on its lateral and posterior border. Sting thick, exserted. Legs rather short, all the tibire furnished with pectinate spurs.

Surface of body shining, except the head, which is subopaque. Mandibles finely and indistinctly striated. Head covered with large, close-set, umbilicate foveolae except on the folds of the posterior angles which are coarsely coriaceous. Whole thorax covered with umbilicate foveolae like those on the head. On the petiole and postpetiole the foveolae are as large as those on the head and thorax but less densely aggregated; on the first gastric segment the foveolae are distinctly smaller and much further apart.

Whole body covered with long, suberect, golden yellow hairs, which on the head, thorax and abdomen, arise from the umbilicate centers of the foveolae. Hairs on the terminal antennal joint very short and dense, contrasting with the longer hairs on the scape and short joints of the funicle.

Color red, edges of mandibles, clypeus, anterior border and posterior angles of head, the funicle with the exception of the terminal joint, the articulations of the thorax, legs and abdomen and the tip of the latter blackish. Legs and terminal antennal joint slightly more yellowish than the remainder of the body.

Queen
Length 3.75 mm.

Eyes moderately large, convex, situated in the middle of the lateral surface of the head, which is shaped like that of the worker. Ocelli well developed, not lying at the corners of an equilateral, but of an isosceles triangle with a long base. Prothorax large, scutum of mesonotum well developed, dorsally flattened, without parapsidal sutures; tegulae large, elliptical; no paraptera between the scutum and the well-developed, flattened scutellum, metanotum narrow but distinct; epinotum large, shaped like that of the worker. On the pleural surface the mesothoracic epimerite and episternum are distinct but these elements in the metapleune are more obscurely separated. There is nothing to show that the thorax has ever borne wings. Petiole longer than broad, postpetiole almost twice as broad as the petiole, its posterior border nearly coextensive with the edge of the first gastric segment, which is both broader and longer than this segment in the worker. Terminal gastric segments and sting in all respects like those of the worker.

The sutures of the thoracic dorsum are blackened; otherwise the female is like the worker in coloration, sculpture and pilosity.

Male
Smith (1942) - Male.-Length 3.2-3.5 mm.

Head measured through the eyes approximately 1.15 to 1.25 times as broad as long. Mandible well developed, masticatory border curved, ending in a long tooth, remainder of border toothless or with very minute teeth. Anterior border of c1ypeus with a median tooth or angular projection. Antennal fossa contiguous with posterior border of clypeus. Frontal carinae subparallel, not concealing articulations of antennal scapes. Clypeus broader than long. Eye large, very convex, placed near anterior border of head. Ocelli prominent, placed at summit of head. Posterior border of head round, meeting each side to form a rather distinct, subangular, posterior corner. Antenna 13-segmented; scape very slightly longer than combined length of first 2 funicular segments, funiculus gradually enlarging apically, segments robust, last funicular segment longer than combined length of the 2 preceding segments. Pronotum less than one-third as long as mesonotum, strongly inclined, but not concealed by mesonotum. Parapsidal sutures but no Mayrian furrows, the former seen only in certain lights. Front wing with a very large stigma, discoidal cell absent or present but without cubital or radial cell. Legs moderately long, tibial spurs pectinate, spurs on front and hind tibiae especially well developed. Anterior three-fifths of mesonotum convex in profile. Petiole non pedunculate, sybcylindrical in profile, slightly flattened above, approximately one and one third times as long as high. First gastric segment distinctly higher than long. Gaster subelliptical from above, with distinct constrictions between the segments. Sixth gastric tergite without an impressed area (pygidium). Seventh gastric sternite with a forked process, each fork slender, narrowed and curved apically, with the point directed slightly dorsad.

Body smooth and shining, with the following exceptions: Coarse rugulae between mesonotum and scutellum, and fine reticulae on side of scutellum, and on metanotum; a few scattered, piligerous punctures on the body, these especially noticeable on summit of head, mesonotum, and posterior part of dorsal surface of gaster.

Hairs moderately abundant, slender, grayish, unusually long at apex of gaster; row of hairs at posterior border of each gastric segment; pubescence rather dense and closely appressed on funiculus, apparently longer and less appressed on legs.

Rather uniform dark reddish brown; legs lighter.

Type Material
Austin, Texas. Within the city limits, May 11 1902. Miss Augusta Rucker.