Schedorhinotermes Silvestri, 1909

Takematsu, Yoko & Vongkaluang, Charunee, 2012, A taxonomic review of the Rhinotermitidae (Isoptera) of Thailand, Journal of Natural History 46 (17 - 18), pp. 1079-1109 : 1098-1099

Schedorhinotermes Silvestri, 1909

Type species: Schedorhinotermes intermedius (Brauer, 1865)

The genus has dimorphic soldiers and the major soldier and minor soldier are very different morphologically. The diagnostic characters used in keys are mainly head shape, size and the number of antennal segments, but sometimes these characters are variable even within a colony. The morphological differences of minor soldiers are very small and it is impossible to identify the species by using the conventional diagnostic characters of minor soldiers. The proportion of minor soldiers is much larger than majors, and it is not unusual to collect only minor soldiers. Therefore it is important to be able to identify the species from the minor soldiers.

There are more than 20 species in the Indomalayan region. Gathorne-Hardy (2004) observed many specimens of Schedorhinotermes from the region and synonymized several species. Three species are recorded from Thailand. One was described by Ahmad (1965) but the diagnostic characters of minor soldiers were too vague to distinguish them from the other two species.

In this paper, I present clear differences among species of both major and minor soldiers.

Diagnosis – Dimorphic soldiers

Major soldier. Head subrectangular, slightly to greatly narrowed anteriorly. Fontanelle open and circular, with a groove running to the tip of the labrum. Eyes absent. Labrum weakly bi-lobed at tip. Left mandible with two marginal teeth; right mandible with one marginal tooth. Postmentum club-shaped. Pronotum flat.

Minor soldier. Much smaller than the major soldier. Head subrectangular. Fontanelle open and circular, with a groove running to the tip of the labrum. Labrum long, extended beyond mandibles; tip bi-lobed. Left mandible with two marginal teeth; right mandible with one marginal tooth. Postmentum club-shaped. Pronotum flat.

Key to species of Schedorhinotermes in Thailand

Major soldier

1. Larger species, head length without mandible more than 2.0 mm, maximum width of head more than 2.2 mm ................ S. malaccensis (Holmgren) Smaller species, head length without mandible less than 1.9 mm, maximum width of head less than 1.7 mm .......................................... 2

2. Head capsule and pronotum with several hairs ( Figure 11A,C ). Inner edge of apical tooth of left mandible convex. The basal part of right mandible with a broad step ( Figure 11E arrow)................ S. medioobscurus (Holmgren) Head capsule and pronotum without hair ( Figure 12A,C ). Inner edge of apical tooth of left mandible not convex. The basal part of right mandible without a broad step ( Figure 12E )............................ S. rectangularis Ahmad

Minor soldier

1. Larger species, head length without mandible more than 0.95 mm, maximum width of head more than 0.95 mm. Head almost parallel sided or slightly convex ( Figure 10F )............................ S. malaccensis (Holmgren) Smaller species, head length without mandible less than 0.90 mm, maximum width of head less than 0.80 mm. Head widest at posterolateral end of antennal sockets........................................................ 2

2. Apical teeth short, weakly incurved, DAM1 / DM1M2 less than 1.3 ( Figure 11J ). Postmentum without a projection, smoothly arched in the lateral view ( Figure 11G )........................... S. medioobscurus (Holmgren) Apical teeth long, strongly incurved, DAM1 / DM1M2 more than 1.3 ( Figure 12J ). Postmentum with a faint projection at anterior one-third in the lateral view ( Figure 12G arrow).................... S. rectangularis Ahmad

Figures

Figure 10. Soldier of Schedorhinotermes malaccensis (Holmgren). (A) Head of major soldier, dorsal view; (B) head of major soldier, lateral view; (C) pronotum of major soldier; (D) postmentum of major soldier; (E) mandibles of major soldier; (F) head of minor soldier, dorsal view; (G) head of minor soldier, lateral view; (H), pronotum of minor soldier; (I) postmentum of minor soldier; (J) mandibles of minor soldier. Scale bar 0.5 mm.

Figure 11. Soldier of Schedorhinotermes medioobscurus (Holmgren). (A) Head of major soldier, dorsal view; (B) head of major soldier, lateral view; (C) pronotum of major soldier; (D) postmentum of major soldier; (E) mandibles of major soldier; (F) head of minor soldier, dorsal view; (G) head of minor soldier, lateral view; (H) pronotum of minor soldier; (I) postmentum of minor soldier; (J) mandibles of minor soldier. Scale bar 0.5 mm.

Figure 12. Soldier of Schedorhinotermes rectangularis Ahmad.(A) Head of major soldier, dorsal view; (B) head of major soldier, lateral view; (C) pronotum of major soldier; (D) postmentum of major soldier; (E) mandibles of major soldier; (F) head of minor soldier, dorsal view; (G) head of minor soldier, lateral view; (H) pronotum of minor soldier; (I) postmentum of minor soldier; (J) mandibles of minor soldier. Scale bar 0.5 mm.