Acanthotermes acanthothorax Sjöstedt, 1898 刺胸刺白蚁

Morphology

The description below is paraphrased from the original or a later revision, by caste; the source is cited at the end.

Diagnostic characters

The soldier is dimorphic, with major and minor forms, and this is the most striking character of the genus; the alate has 20–23 antennal segments, the male with 1–2 more than the female, and the soldier 17–20. The anterior margin of the pronotum bears spines, and the lateral margins of the thoracic nota are more or less acute. All known species occur in Africa.

Alate

The head is broad and nearly circular. The compound eyes are medium-sized and projecting; the ocelli are slightly lateral and nearly circular, about one eye diameter from the compound eyes. Frontal gland pores are present. The base of the clypeus is even longer than half its width, rather narrow, strongly convex behind and straight in front, fairly raised, and distinctly brighter than the frons; the apex of the clypeus is transparent. The labrum is longer than wide and bears a chitinous transverse band. The mandible dentition is of the Termes type, tooth 1 of the left mandible slightly larger than tooth 2. The pronotum bears two small nodular projections on each side of the midline. The posterior emargination of the mesonotum is slightly wider than that of the metanotum. The wings are transparent, with brown veins at the base and along the anterior margin and a weakly reticulate membrane; the radial vein is reduced and does not extend beyond the wing scale; in the forewing the media is separate from the wing scale, while in the hindwing the media arises from the base of the radial sector, is slender, and branches towards the radial sector and the wing apex; the cubitus has a thickened internal vein. The sides of the abdomen bear exudate hairs, denser in the female; the male has styli.

Soldier

Major soldier: the head is more or less narrowed anteriorly, with parallel sides, oval to cordate, its posterior margin straight to strongly concave. The frontal gland pore is distinct, surrounded by a circular hairy area, with a spine-like elevation in front of the pore; the mandibular base is robust. The base of the clypeus is very short, the apex fairly large and transparent. The labrum is fairly broad, its apex trilobed and transparent. The mandibles are fairly short and robust, more or less strongly curved, each with a more or less sharp large basal tooth; the left mandible has in addition 3 to several fairly small nodular teeth, and the base of its apex often bears a notch and a tooth-like projection; the rest of the right mandible is toothless. The submentum is long, narrow and parallel-sided. The anterior margin of the pronotum bears two acute projections on each side of the midline, fairly small, and the anterior corners are fairly sharp; the lateral parts of the meso- and metanota are more or less acute. The legs are long, the last tarsomere distinctly longer than the rest together and slender. The cerci are large; the styli are present and small, or reduced. Minor soldier: the head is fairly parallel-sided, oval, widest at the level of the antennae; in profile both upper and lower surfaces are fairly convex, the lower especially wrinkled. The frontal gland pore is likewise surrounded by a ring of hairs, sometimes forming a tubular elevation, with a distinct spine on its anterior margin. The clypeus is fairly short, convex behind and straight in front, with a transparent apex. The labrum is pointed, its apex transparent and trilobed. The mandibles are narrow and weakly sickle-shaped; the base of the left mandible bears a tooth scar and the basal tooth is weakly developed. The antennae are long, with 15–20 segments, segment 2 shorter than segment 3. The submentum is longitudinally elongate, strongly convex, narrow and parallel-sided. The anterior margin of the pronotum bears spines. The cerci are large; the styli are present.

Worker

The worker is dimorphic. The head is large, broadly oval, with a distinct coronal suture, and the frontal gland pore is large and triangular. The base of the clypeus is short, far less than half its width, raised, and the apex is large. The labrum is longer than wide and bears a chitinous transverse band. The mandibles are shorter and wider than in the alate but with the same dentition. There are 17–21 antennal segments, segment 2 longer than segment 3. The pronotum has robust anterior projections. The legs are long, and the trochanter of the foreleg bears two robust anterior setae. The cerci are large; the styli are reduced.

This genus is monotypic, containing only this species; the following is the genus-level description based on the original literature; species-level measurements and intraspecific variation are given in the original.