Aenictus fulvus, Jaitrong, Weeyawat & Yamane, Seiki, 2011

Jaitrong, Weeyawat & Yamane, Seiki, 2011, Synopsis of Aenictus species groups and revision of the A. curra x and A. laeviceps groups in the eastern Oriental, Indo-Australian, and Australasian regions (Hymenoptera: Formicidae: Aenictinae), Zootaxa 3128, pp. 1-46 : 34

Aenictus fulvus sp. nov.

( Figs. 28–30 )

Types. Holotype worker from S. Thailand, Nakhon Si Thammarat Prov., Khao Nan, rubber tree plantation, 28 IX 2008, W. Jaitrong leg., WJT08-S1101 (THNHM). One hundred and thirty-seven paratype workers, same data as holotype (AMK, BMNH, MCZC, MHNG, SKYC, THNHM, UMS).

Measurements. Holotype and paratypes (n = 10): TL 2.95–3.10 mm; HL 0.63–0.75 mm; HW 0.53–0.65 mm; SL 0.48–0.60 mm; ML 0.90–1.05 mm; PL 0.23–0.25 mm; CI 84–87; SI 90–92.

Description of worker (holotype and paratypes). Head in full-face view subrectangular, much longer than broad, with sides rather parallel or feebly convex and posterior margin almost striaght; occipital carina complete. Antennal scape relatively short, not reaching posterolateral corner of head; antennal segments II–X each longer than broad; II almost as long as each of III–VII. Frontal carina very short, not extending beyond posterior margin of torulus. Anterior margin of clypeus feebly convex, bearing 4–6 denticles. Masticatory margin of mandible with a large apical tooth followed by a small subapical tooth, 3–4 denticles and a medium-sized basal tooth; basal margin bearing 2–3 small teeth. Mesosoma relatively slender; promesonotum in profile weakly convex dorsally and sloping gradually to metanotal groove; propodeum with dorsal outline almost straight; propodeal junction roundly angulate; declivity not margined dorsally and laterally. Petiole subsessile, almost as long as high; subpetiolar process well developed and hook-like, its apex directed downward and backward; postpetiole almost as long as petiole, only slightly higher than the latter.

Head including mandible and antennal scape entirely smooth and shiny. Mesosoma extensively smooth and shiny; area of metanotal groove striate; upper portion of metapleuron with about 10 irregular longitudinal rugae. Petiole and postpetiole entirely smooth and shiny. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs over the surface; longest pronotal hair 0.25–0.30 mm long. Body reddish-brown to yellowish-brown; dorsum of head darker. Typhlatta spot located anterior to occipital corner.

Non-type material examined. MALAYSIA: W. Malaysia, Selangor, Ulu Gombak, ca. 25 m alt., 19 X 1999, V. Witte leg., VW-03 ( SKYC, THNHM); same loc., VII-X 1992, F. Ito leg., FI92MG-651 ( SKYC, THNHM); same loc., ca. 25 m alt., 10 IX 1999, V. Witte leg., VW-04 ( SKYC, THNHM); same loc., ca. 25 m alt., 3 XII 2005, AT1086 ( SKYC, THNHM); Sabah, Danum Valley, 3 XI 1996, K. Eguchi leg., Eg96-BOR-152 ( SKYC); same loc., 29 IV 2000, C. Brühl leg. ( SKYC); Sabah, Tawau Hills, Gunong Rara, 18 II 1997, K. Eguchi leg., Eg97-BOR-518 ( SKYC, THNHM); same loc., 8 VII 1996, Sk. Yamane leg., SB96-SKY-11 ( SKYC, THNHM); Sarawak, Miri, Lambir N.P., 14 I 1993, Sk. Yamane leg. ( SKYC, THNHM); same loc., 26 VI 2004, Sk. Yamane leg., SR04-SKY- 12 ( SKYC, THNHM); Sarawak, Niah N.P., 9 I 1993, Sk. Yamane leg. ( SKYC, THNHM). BRUNEI: Temburong, Kuala Belalong field studies centre, 19 II 1999, K. Eguchi leg., Eg99-BOR-224. INDONESIA: E. Kalimantan, Rainforest, Sungai Wain Protection Area, 13 III 2001, G. Fredriksson leg. ( SKYC).

Etymology. The specific name pertains to the pale body colour.

Distribution. Malay Peninsula (S. Thailand and W. Malaysia), and Borneo (Sabah, Sarawak, Brunei, and E. Kalimantan) ( Fig. 63 ).

Bionomics. Aenictus fulvus is probably a Sundaland species. We found a colony in a rubber tree plantation in southern Thailand (type series). Elsewhere it has been collected mostly in lowland primary rainforests. The type series was found under a large rotting log during the wet season; no worker activity was seen around the log and no immatures were found in the bivouac. We found this species preying on the ant genus Crematogaster (type series).

Remarks. A. fulvus is quite similar to A. alticola and A. luzoni in having a slender body with the surface almost smooth and shiny. Compared with these species, A. fulvus is much smaller (HW 0.53–0.65 mm in A. fulvus ; 0.80– 0.85 mm in A. alticola ; 0.78 mm in A. luzoni ) and has a low subpetiolar process without anterior angle, and ventrally with a spiniform appendage directed downward and backward (in A. alticola and A. luzoni the subpetiolar process is low and anteriorly angulate with the ventral appendage not spiniform).

The workers of three colonies from Ulu Gombak, Malay Peninsula (FI92MG-651, VW-04, and VW-03) are brighter than in the type series from Khao Nan National Park, southern Thailand. The size variation occurs among individuals from single colonies.

Figures

FIGURES 26 – 32. Workers of Aenictus laeviceps group. 26, 27, A. alticola, lectotype; 28 – 30, A. fulvus sp. nov., holotype; 31, 32, A. luzoni, lectotype. 26, 28, 31, Head in full-face view; 27, 29, 32, habitus in profile; 30, dorsal view of body.

FIGURES 63 – 66. Distribution of Aenictus laeviceps group. 63, A. alticola, A. binghami, and A. fulvus sp. nov., A. luzoni; 64, A. bodongjaya sp. nov., A. breviceps, A. brevinodus sp. nov., and A. montivagus sp. nov.; 65, A. hodgsoni, and A. laeviceps; 66, A. sonchaengi sp. nov., A. rotundicollis sp. nov., and A. siamensis sp. nov.