Sandsitermes robustus Holmgren, 1906 粗壮桑兹白蚁

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 dorsal surface of the alate head is slightly raised anterior to the fontanelle at the position of the ocelli; the postclypeus is slightly arched, with a straight anterior margin and a slightly convex posterior margin; the molar region of the right mandible is distinctly concave, with weak ridges and a distinct basal concavity. The soldier nasus is long-conical but has no unique morphological character (the original explicitly states 'no apparent uniquely distinct morphological character'). The worker mandible has a concave molar region without well-developed ridges; P1 of the gut forms a separate loop before joining the paunch (P3); the enteric valve (P2) is weakly sclerotised, arranged in two rings, with minute conical spines.

Alate

Head capsule oval in dorsal view; the frontal region between the ocelli is not concave; in lateral view the dorsal surface of the head is slightly raised anterior to the fontanelle at the position of the ocelli. Compound eyes oval and large, closer to the lower margin of the head than to the ocelli. Ocelli elliptical and large in dorsal view (smaller than the antennal socket), situated in the anterior half of the compound eye, their distance from the compound eye less than the width of an ocellus. Fontanelle paler than the head, situated in a shallow depression, Y-shaped, the anterior arms short, with a small transparent circle above the arms. Postclypeus slightly arched in lateral view, slightly concave along the midline in dorsal view; anterior margin straight, posterior margin slightly convex. Antennal segments 15. Pronotum wider than the head (excluding the eyes), sub-trapezoidal, the anterior margin raised, the anterolateral angles rounded, the lateral margins concave and narrowing posteriorly, the posterior margin rounded and not concave. The posterior margins of the meso- and metanotum deeply concave, the posterolateral angles acute. Spur formula 2:2:2.

Soldier

Monotypic. Head capsule oval to round in dorsal view, not constricted, the posterior margin not concave; in lateral view the vertex is slightly raised at the base of the nasus, with a shallow depression behind it. Nasus conical, shorter than the head capsule, not upturned; postclypeus slightly convex in lateral view. Labrum wider than long, the anterior margin rounded, the lateral margins parallel, the anterior angles rounded. Mandibles with a distinct 'point'. Antennal segments 13. The anterior lobe of the pronotum is less developed than the posterior lobe, the angle between them about 90°. Fore coxa conical, without a keel on the anterior face. Spur formula 2:2:2. Abdominal sclerites well sclerotised, the tergites imbricate.

Worker

All workers with a trapezoidal head capsule; fontanelle distinct, situated in the middle of the head capsule, slightly concave; postclypeus inflated; antennal segments 14; anterior margin of the pronotum rounded and not concave; spur formula 2:2:2. Workers dimorphic, distinguished by head capsule pigmentation, mandible form and the shape and size of the tergites: type 2 is less numerous than type 1 in all samples examined, the head capsule brownish yellow, with a concavity anteriorly and a swelling behind it; the outer margin of the mandible has a distinct concavity in front of the apical tooth, the apical tooth is larger, the gap between left M3 and the molar prominence is wider, and the molar plate is narrower; the anterior lobe of the pronotum is more developed than the posterior lobe. Within type 1 the head capsule size appears to vary, but the number of individuals is insufficient for measurement.

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.