Genus Trinervitermes · 三脉白蚁属

Morphology

The descriptions below are an adaptation of the original genus-level accounts; terms follow the meaning of the source, and the original is not transcribed verbatim.

Diagnostic characters

In the alate, the first marginal tooth of the left mandible is about as long as the second (rather than distinctly longer), the left mandibular index is 0.29–0.41, the second marginal tooth is absent, and the cutting edge between the first and third marginal teeth is straight; the cutting edge behind the first marginal tooth of the right mandible is distinctly longer than that behind the second marginal tooth; the surface contour of the right molar plate shows no marked irregularity, bearing 5–9 transverse ridges, the first much larger than the rest and blunt-toothed in form, the posterior ridges weaker. The postclypeus is about equal to or slightly more than half as long as wide; the fontanelle is pale, slit-like, forked anteriorly into an almost triangular shape, the two arms enlarged or tapering at their ends; the cephalic pilosity is uniformly fine and dense, the hair pits regular in size, interspersed with a few larger pits; in large species the antennae have 15–16 segments and the pronotum is broad. The soldier is dimorphic in most species, showing traces of a major/minor differentiation or an almost continuous series; the nasus is cylindrical to broadly conical, the apical process of the mandibles is usually lost, the head capsule is not at all constricted behind the antennal fossae and bears no conspicuous setae except on the nasus (major soldier; the head capsule of the minor soldier is often constricted). It is distinguished from Nasutitermes by the longer mandibular cutting edges of the alate and by the structure of the right molar plate; its closest relative is the monomorphic-soldier genus Baucaliotermes. Sands described it as the most difficult genus in the subfamily and indeed in the Isoptera.

Alate

The apical tooth of the left mandible is equal to or slightly shorter than the first marginal tooth, the distance from the apical tooth to the first marginal tooth being slightly less to slightly more than one-third of the distance between the first and third marginal teeth (left mandibular index 0.29–0.41); the second marginal tooth is absent; the cutting edge between the first and third marginal teeth is straight; the apical and first marginal teeth of the right mandible are as in the left, and the cutting edge behind the first marginal tooth is distinctly longer than that behind the second marginal tooth; the surface contour of the molar plate shows no marked irregularity, bearing 5–9 transverse ridges, the first much larger than the rest and blunt-toothed in form, the more posterior ridges weaker. The postclypeus is slightly less to slightly more than half as long as wide. The fontanelle is pale, slit-like, forked anteriorly into a nearly triangular shape, the two arms enlarged or tapering at their ends. The cephalic pilosity is fairly uniform and fine, arising from small hair pits of regular size, with a few larger pits scattered among them.

Soldier

Dimorphic in most species, with traces of a major/minor differentiation, or in some colonies and local populations almost completely continuous. The nasus is cylindrical to broadly conical. The apical process of the mandibles is usually lost. The head capsule is not at all constricted behind the antennal fossae and bears no conspicuous setae except on the nasus (major soldier; the head capsule of the minor soldier is often constricted).

Sources: Sands, W.A. 1965. A revision of the termite subfamily Nasutitermitinae (Isoptera, Termitidae) from the Ethiopian Region. Bulletin of the British Museum (Natural History), Entomology, Supplement 4: 1–172., p. 76–77（Genus Trinervitermes: Imago, Soldier） This text is an adaptation, not a verbatim transcription of the original.