Reticulitermes assamensis Gardner , 1944

Takematsu, Yoko & Vongkaluang, Charunee, 2012, A taxonomic review of the Rhinotermitidae (Isoptera) of Thailand, Journal of Natural History 46 (17 - 18), pp. 1079-1109 : 1096-1098

Reticulitermes assamensis Gardner, 1944

( Figures 9A–E , 13E )

Reticulitermes assamensis Gardner, 1944: 105–106 .

Material examined

THAILAND: Nan: seven series, Doi Phu Kha National Park , 1400 m alt., 7 December 2003, Y. Takematsu coll. ; Leoi: Phu Luang National Park , 1050 m alt, 13 December 1996, Y. Takematsu coll. ; Nakhon Ratchasima: two series, Khao Yai National Park ,

700 m alt., 1 December 1998, Y. Takematsu coll.; Khao Yai National Park, 700 m alt., 4 March 1998, Y. Takematsu coll.; Khao Yai National Park, 500 m alt., 4 March 1998, Y. Takematsu coll.; four series, Khao Yai National Park, 1200 m alt., 4 March 1998, Y. Takematsu coll.

Redescription

Soldier. Head capsule pale yellow; antennae pale yellow; labrum yellow; mandibles dark brown, paler basally; thorax and abdomen yellowish white. Head fairly hairy; pronotum fairly hairy with 20–40 hairs on the surface. Postmentum with several hairs in the anterior half. Head capsule rectangular, parallel-sided or slightly concave at posterolateral ends of antennal sockets, much longer than wide, maximum width slightly more than half of the length, mHW / HL 0.53–0.60 (0.56); frontal protuberances prominently swollen. Fontanelle minute, located a little behind middle of frontal protuberances. Antennae with 14–17 segments. The number of segments increases as the body size increases. Labrum triangularly tongue-shaped, with a pair of long bristles at tip. Mandibles weakly incurved; length slightly more than half of head length. Left mandible with three small crenulations and a basal projection; right mandible with straight inner margin. Postmentum club-shaped with a long narrow stalk, narrowest part almost 10 times as long as length, minimum width of postmentum 0.12–0.18 (0.15). Pronotum flat, narrower than head, with anterior margin slightly concave, notched in middle.

Measurements (mm)

Comparison of measurements of Thai specimens with Reticulitermes assamensis and Reticulitermes tirapi is given in Table 2

Distribution

Thailand (Northeast, North), India, China. New record for Thailand. Remarks

The samples collected from Thailand are morphologically the same as R. assamensis and R. tirapi Chhotani and Das, 1983 from India and southern China. They are distinguished from the other Reticulitermes species by having a longer and narrower head, many setae on pronotum, almost straight mandibles and distinctly prominent frontal projection. Chhotani and Das (1983) distinguished R. tirapi from R. assamensis by the narrower head and pronotum; however, the measurements of these characters overlap and these two species cannot be distinguished by the descriptions. The specimens in Thailand increased in size towards the north and were relatively smaller than the sizes given in Chhotani and Das (1983), although they could not be separated clearly. As the results, I concluded that the species in Thailand is R. assamensis and showed a geographical cline from south to north. To clarify the relationship of R. assamensis and R. tirapi , further investigation is needed.

In Thailand it is distributed only at mid to high elevations (500–1400 m) in the central mountain ranges, Luan Phrabang mountain range and Phetchabun mountain range ( Figure 13E ). It is possibly a relic distribution from the last glacial maximum .

Figures

Figure 9. Soldier of Reticulitermes assamensis Gardner. (A) Head, dorsal view; (B) head, lateral view; (C) pronotum; (D) postmentum; (E) mandibles. Scale bar 0.5 mm.

Figure 13. Distribution of Coptotermes and Reticulitermes in Thailand. (A) Coptotermes curvignathus; (B) Coptotermes gestroi; (C) Coptotermes kalshoveni; (D) Coptotermes premrasmii; (E) Reticulitermes assamensis. (Record of C. premrasmii is from original description.)