Aenictus laeviceps (F. Smith)

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 : 36-40

Aenictus laeviceps (F. Smith)

( Figs. 57–62 )

Typhlatta laeviceps F. Smith, 1857: 79 .

Aenictus (Typhlatta) laeviceps: Wheeler, 1930: 199 (in key), 200–203 (queen). Aenictus laeviceps: Wilson, 1964: 467 , Figs. 15–17 , 88 (part); Bolton, 1995: 60 (part). Eciton (Aenictus) fergusoni var. sundaica Karavaiev, 1927: 7 (synonymized with A. laeviceps by Wilson, 1964: 467). Type

locality: Prinsen I. [Panaitan I.], Sunda Strait, nr Java.

Types. Typhlatta laeviceps: Three syntype workers from Borneo, Sarawak (BMNH and OXUM, examined). A syntype in BMNH is selected as the lectotype, others as paralectotypes.

Measurements. A worker lectotype: TL 4.15 mm; HL 0.93 mm; HW 0.80 mm; SL 0.83 mm; ML 1.35 mm; PL 0.33 mm; CI 86; SI 103. Non-type workers (n = 9): TL 3.90–4.15 mm; HL 0.88–0.92 mm; HW 0.70–0.82 mm; SL 0.73–0.87 mm; ML 1.30–1.40 mm; PL 0.28–0.33 mm; CI 86–92; SI 103–113.

Redescription of worker (lectotype and non-type material from Borneo). Head in full-face view clearly longer than broad, with sides and posterior margin strongly convex; occipital margin bearing a carina. Antenna relatively long, scape almost reaching the posterolateral corner of head; antennal segments II–X each longer than broad. Frontal carina short, slightly extending beyond the level of the posterior margin of torulus. Anterior margin of clypeus convex, bearing 6–8 denticles. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth, 4–5 denticles, and a medium-sized basal tooth; basal margin lacking denticles. Promesonotum in profile convex dorsally; propodeum much lower than promesonotum, and in profile its dorsal outline almost straight; propodeal junction right-angled; declivity of propodeum weakly concave, encircled with an indistinct rim. Mesopleuron demarcated from metapleuron by a shallow groove. Petiole longer than high, in profile its dorsal outline almost straight or weakly convex in posterior portion; subpetiolar process well developed, its lobe surmounted by a thin, acute flange that is directed downward and backward; postpetiole slightly shorter than petiole, in dorsal view scarcely longer than broad.

Head entirely smooth and shiny. Antennal scape microrecticulate and subopaque, slightly shiny. Mandible finely microsculptured and feebly shiny. Pronotum smooth and shiny, its anteriormost portion punctate; mesothorax, metapleuron and propodeum with dense punctures; upper portion of mesopleuron and metapleuron with 15-20 irregular longitudinal rugulae; propodeum with about 40 densely packed, nearly straight, fine rugulae; interrugal spaces irregulary microrecticulate and opaque to feebly shiny. Petiole with dense punctures; postpetiole entirely smooth and shiny. Femora extensively but superficially reticulate and shiny; tibiae very finely reticulate.

Head with a pair of standing hairs on vertex; mesosoma devoid of pilosity. Entire body dark reddish brown. Typhlatta spot located anterior to occipital corner.

Non-type material examined. THAILAND: E. Thailand, Sakhao Prov., Pang Sida, 29 V 2006, W. Jaitrong leg., WJT06-E382 ( AMK, SKYC, THNHM); E. Thailand, Chachoengsao Prov., Ang Reu Nai, Baw Thong, Khao 29 X 2005, W. Jaitrong leg., THNHM-I05-3401 ( AMK, SKYC, THNHM); E. Thailand, Chanthaburi Prov., Nam Tok Pheao, Nam Tok Troknong Waterfall, EF, 23 XI 2003, D. Wiwatwitaya leg. ( AMK); same loc., 29 XI 2003, W. Jaitrong leg., WJT02-TH492 ( AMK, SKYC, THNHM); same loc., 300–500 m alt. 23 XI 2003, Sk. Yamane leg., TH03-SKY-134 ( SKYC, THNHM); E. Thailand, Chanthaburi Prov., Khao Soi Dao, 19 VII 1997, Sk. Yamane leg., TH99-SKY-04 ( SKYC, THNHM); S. Thailand, Phang Nga Prov., Khao Lak Lam Loo, EF, 3 VI 2000, W. Jaitrong leg., WJT00-KL01 ( AMK, SKYC, THNHM); S. Thailand, Ranong Prov., Khlong Naka, EF, 12 VIII 2009, W. Jaitrong leg., WJT09-TH2049 ( AMK, SKYC, THNHM); S. Thailand, Nakhon Si Thammarat Prov., Khao Nan, 11 XII 2007, W. Jaitrong leg., WJT07-KN02 ( AMK, SKYC, THNHM); same loc., San Yen, 1,095 m alt., 8 IV 2007, W. Jaitrong leg., WJT07-TH682 ( AMK, SKYC, THNHM); S. Thailand, Trang Prov., Khao Chong Botanical Garden, 29 X 2007, P. Kosolpanyapiwat leg., PPK07-4 ( AMK, SKYC, THNHM); same loc., EF, 10 VIII 2009, W. Jaitrong leg., WJT09-TH2028 ( AMK, SKYC, THNHM); same loc., 25 V 2005, D. Lohman leg., KC-A007-01 ( SKYC, THNHM); S. Thailand, Trang Prov., Yantakhao Dist., Thung Khai B.G., 9 VIII 2009, W. Jaitrong leg., WJT09-TH2011 ( AMK, SKYC, THNHM); same loc., DEF, 10 VIII 2009, W. Jaitrong leg., WJT09-TH2016 ( AMK, SKYC, THNHM). MALAYSIA: Borneo, Sarawak, Miri, Lambir N.P., 22 VIII 1995, Sk. Yamane leg. ( SKYC, THNHM); same loc., 7 VIII 1995, Sk. Yamane leg. ( SKYC, THNHM); same loc., 7 I 1993, Sk. Yamane leg. ( SKYC, THNHM); same loc., Bt. Pantu, 16 I 1993, Sk. Yamane leg. ( SKYC, THNHM); same loc., 12 I 1993, Sk. Yamane leg. ( SKYC, THNHM); same loc., 15 VII 1993, Sk. Yamane leg. ( SKYC, THNHM); same loc., 20 I 1993, Sk. Yamane leg ( SKYC, THNHM); same loc., 14 VIII 1997, Sk. Yamane leg. ( SKYC, THNHM); same loc., 30 VI 2004, Sk. Yamane leg., SR04-SKY-37 ( SKYC, THNHM); same loc., 16 VIII 1997, Sk. Yamane leg., SA9701816-03 ( SKYC, THNHM); Sarawak, Semangoh N.P., 18 IV1993, Sk. Yamane leg. ( SKYC, THNHM); Sarawak, Bako N.P., 21–22 IV 1993, Sk. Yamane leg. ( SKYC, THNHM); Sabah, Kinabalu N.P., Poring, 20 V 1997, H. Hirosawa leg. ( SKYC); same loc., 600 m alt., 8 X 1997, T. Kikuta leg., 43A ( SKYC); same loc., 700–800 m alt., 15 III 1995, Sk. Yamane leg. ( SKYC, THNHM); same loc., 15 III 1995, Y. Hashimota leg. ( SKYC); same loc., 500–600 m alt., 17 III 1995, Sk. Yamane leg. ( SKYC, THNHM); Sabah, Danum Valley, 29 VIII 1995, Sk. Yamane leg. ( SKYC, THNHM); same loc., 9 XI 1996, K. Eguchi leg., Eg96-BOR-249 ( SKYC). BRUNEI: Tasek Merimbun, 15 II 1999, E. Eguchi leg., Eg99-BOR-121 ( SKYC). PHILIPPINES: Negros Oriental, Valencia near Dumaguete, Apolong, 30 XII 1998, Sk. Yamane leg., PH 98-SKY-26 ( SKYC, THNHM). INDONESIA: N. Sumatra, G. Leuser N.P., Bt. Lawang, 17 VIII 2002, Sk. Yamane leg., SU02-SKY-50 ( SKYC, THNHM); W. Sumatra, Lubuk Gadang, 21–23 VIII 1985, Sk. Yamane leg. ( SKYC, THNHM); W. Sumatra, Maninjau, 7–9 VIII 1985, So. & Sk. Yamane leg. ( SKYC); W. Sumatra, nr Padang, Ulu Gadut, 24 VIII 1989, E. Suzuki leg. ( SKYC); same loc., Pinang-pinang, 20 III 1997, F. Ito leg., FI97-321 ( SKYC); same loc., Pinang-pinang, 18 XI 2008, K. Nakamura leg., SU08-Kei295 ( SKYC, THNHM); W. Sumatra, Paykunbuh, Gunung Bungsu, 12 XI 2008, K. Nakamura leg., SU08-Kei145 ( SKYC, THNHM); same loc., Buluh Kasap, 14 XI 2008, K. Nakamura leg., SU08-Kei282 ( SKYC, THNHM); same loc., Gunung Sagou, 13 XI 2008, K. Nakamura leg., SU08-Kei146 ( SKYC, THNHM); same loc., Mt. Sago, 13 XI 2008, K. Nakamura leg., SU08-Kei27 ( SKYC, THNHM); W. Sumatra, Andalas University, 21 X 2008, K. Nakamura leg., SU08-Kei27 ( SKYC); S. Sumatra, Lampung Barat, Sumberjaya, Bodong Jaya, SF, 18 IX 2007, Sk. Yamane leg., SU07-SKY-199 ( SKYC, THNHM).

Distribution. E. Thailand, Malay Peninsula (S. Thailand and W. Malaysia), Sumatra, Borneo (Sabah, Sarawak, and Brunei), and Philippines ( Fig. 65 ).

Bionomics. A. laeviceps is widespread and dominant in rainforests of Southeast Asia ( Gotwald 1995). We found it foraging in lowland seasonal forests (dry evergreen forest) in eastern Thailand. Elsewhere it was collected from tropical rainforests generally at less than 1,000 m alt. A single colony may contain as many as 60,000 to 110,000 workers ( Schneirla & Reyes 1966).

This species forages mainly on the ground ( Hirosawa et al. 2000) but sometimes climbs up trees. We observed this species preying on other ants such as Anoplolepis gracilipes ( Philippines, PH 98-SKY-26; Thailand, WJT09- TH2016), Camponotus (Sumatra, SU08-Kei295; Thailand, WJT09-TH2028), Euprenolepis ( Thailand, WJT09- TH2028), Polyrhachis (Borneo, SA970816-03), Pseudolasius (Borneo, SR04-SKY-37), and also on grasshoppers ( Thailand, WJT09-TH2016). Wilson (1964) mentioned that A. laeviceps preyed on other ant species such as Camponotus (Tanaemyrmex) carin , Diacamma sp., Echinopla sp., Hypoclinea sp. [ Dolichoderus sp.], Myrmicaria sp., Pristomyrmex sp., Paratrechina longicornis , Polyrhachis (Polyrhachis) bellicosa , Polyrhachis (Myrmhopla) sp., and Polyrhachis (Myrma) sp., Ponera sp., Vollenhovia sp., and also on the social wasp, Ropalidia flavopicta . Chapman (1964) found this species feeding on myriapods, termites, small staphylinid beetles, while RoŠciszewski and Maschwitz (1994) mentioned that ants of the genera Crematogaster , Paratrechina , Pheidole , Polyrhachis , and Prenolepis were the prey of A. laeviceps . Hirosawa et al. (2000) reported that dominant prey genera were Camponotus (48.2%), Pseudolasius (20.8%) and Polyrhachis (15.2%) in the vicinity of Poring, Sabah, Borneo at altitudes of 600– 800 m.

Remarks. A. laeviceps is closely related to A. breviceps , A. sonchaengi , and A. rotundicollis in having only 2 standing hairs on the vertex of the head. It has a more weakly convex promesonotum in profile than the last two (promesonotum strongly convex in A. sonchaengi and A. rotundicollis ). It is also separated from them by the absence of standing hairs on the pronotum (more than 4 hairs present in A. sonchaengi ; 2–4 hairs in A. rotundicollis ). Another character separating A. laeviceps from A. rotundicollis is the relative length of the petiole, which is longer than high in the former but shorter than high in the latter. For the differences between A. laeviceps and A. breviceps , see ‘Remarks’ for A. breviceps .

The specimens collected from southern Thailand, Sumatra, and Borneo ( Sarawak, Sabah, and Brunei) agree well with the lectotype from Sarawak, except in 2 colonies (SU07-SKY-199 and SU08-Kei282) from Sumatra in which the workers have 1–2 standing hairs on the pronotum. In the single colony ( PH 98-SKY-26) from the Philippines the propodeal junction of the worker is rounder than in the lectotype, and also the body size is slightly smaller.

Zhou (2001) cited Guangxi, southern China as a locality of A. laeviceps , but according to Figs. 76–77 and the distribution range of this species the identification is doubtful.

Figures

FIGURES 57 – 62. Workers of A. laeviceps. 57 – 58, lectotype from Sarawak; 59, 60, specimen from Thailand; 61, 62, specimen from Sumatra. 57, 59, 61, Head in full-face view; 58, 60, 62, habitus in profile.

FIGURES 11 – 16. Workers of Aenictus currax group. 11, 12, A. currax, lectotype; 13, 14, A. huonicus, holotype; 15, 16, A. diclops, paratype. 11, 13, 15, Head in full-face view; 12, 14, 16, habitus in profile.

FIGURES 17 – 22. Workers of Aenictus currax group. 17 – 19, A. parahuonicus sp. nov., holotype; 20 – 22, A. wayani sp. nov, holotype. 17, 21, Head in full-face view; 18, 22, habitus in profile; 19, 20, 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.