Genus Labritermes · 唇白蚁属

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

Soldier head small, cylindrical, height nearly equal to width, the frons inclined towards the postclypeus at about 45°; fontanelle circular, extremely small (diameter about 0.014–0.019 mm); labrum very large and broad (broader than long), asymmetrical, upturned, with a broad hyaline tip in the anterior region and a posteriorly directed posteromedian sclerotised process on the underside; mandibles strongly curved, asymmetrical, the left mandible slightly longer, its inner cutting edge regularly serrate from the tip and ending in four progressively larger teeth, the right mandible more strongly incurved, its dorsal inner edge smooth, with a finely serrate narrow groove; antennae 12-segmented; tibial spur formula 3:2:2. Most closely related to the African genus Foraminitermes, the two sharing several synapomorphies such as the hyaline tip of the soldier labrum, the finely serrate left mandible, 1–2 spine-like processes at the base of the molar region of the right mandible, and the structure of the digestive tract, on which grounds Krishna & Adams (1982) transferred the genus from the Amitermitinae to the Termitinae.

Soldier

Head small, cylindrical, height nearly equal to width, the frons inclined towards the postclypeus at about 45°; frontal gland extremely small, fontanelle circular, extremely small, about 0.014–0.019 mm in diameter, situated just above the frontal slope; labrum very large and broad, broader than long, asymmetrical, upturned, with a broad hyaline tip in the anterior region and a posteriorly directed posteromedian sclerotised process on the underside. Mandibles strongly curved, asymmetrical: the left mandible slightly longer than the right, its inner cutting edge with clear, regular serrations from the tip, extending about 1/3–1/2 of its length, ending in four progressively larger teeth, the posterior edges of teeth 3 and 4 long, the base of tooth 4 with a small cusp; the right mandible more strongly incurved than the left, its dorsal inner edge smooth, with a narrow groove extending from near the base to the tip, the ventral edge of the groove finely serrate, with 1–2 extremely small spine-like processes at the base. Pronotum saddle-shaped, narrower than the head. Antennae 12-segmented; tibial spur formula 3:2:2. Measurements (soldier of the type species L. buttel-reepeni, mm): head length 1.05–1.15, head width 0.58–0.62, head height 0.54–0.59, left mandible 0.58–0.60, right mandible 0.50–0.58.

Worker

Left mandible apical tooth short; marginal teeth 1+2 fused, their posterior edge longer than the apical tooth, the cutting edge nearly straight, evenly continuous with the anterior edge of marginal tooth 3 (no distinct angle); mandible index LA/Li 0.28; marginal tooth 4 small, faintly visible from above, almost hidden behind the molar prominence; molar plate with 4–5 grinding ridges. Right mandible: posterior edge of marginal tooth 1 longer than the apical tooth or than the posterior edge of marginal tooth 2, marginal tooth 2 distinct, its posterior edge concave; molar plate with 3–4 grinding ridges. Digestive tract similar to that of Foraminitermes in several respects: crop enlarged, asymmetrical; gizzard not markedly separated from the crop, more strongly sclerotised; midgut very long (about three times the combined length of crop and gizzard); midgut–hindgut junction simple, transverse, without a mixed segment; four Malpighian tubules arising evenly at this junction, running forwards for some distance and then turning back posteriorly, their bases slightly swollen; P1 tubular and narrow proximally (about the same diameter as the midgut), swollen into a sac distally, entering P2 through a toothless conical enteric valve; P2 less swollen than the distal sac of P1, narrowing into a slender tubular colon and ending at the rectum.

Alate

Head yellow to pale yellow-brown, with three pale circular spots between the ocelli forming a triangle; postclypeus, anteclypeus and labrum cream-yellow; antennae pale yellow; pronotum cream-yellow to pale yellow; wing scales brown; wings and legs pale yellow. Head and pronotum densely covered with setae of varying thickness. Head small, oval, posterior margin broadly rounded; Y suture not visible; fontanelle extremely small, almost invisible, not raised; eyes medium-sized; ocelli large, touching the eye margin; postclypeus convex, divided into two halves by a median suture; antennae with 12+ segments, segment 2 equal to segment 4, segment 3 larger than segments 2 and 4; pronotum 0.77–0.81 times the head width, not saddle-shaped, anterior margin slightly concave, the sides broadly rounded, posterior margin distinctly emarginate; coxa without a sclerotised ridge (unlike Foraminitermes); tibial spur formula 3:2:2. Forewing about 5.90 mm long and 1.52 mm wide.

Sources: Krishna, K.; Adams, C. 1982. The Oriental termite genus Labritermes Holmgren (Isoptera, Termitidae, Termitinae). American Museum Novitates 2735: 1–14., pp. 2–7 This text is an adaptation, not a verbatim transcription of the original.