Review of the Southeast Asian species of the Aenictus javanus and Aenictus philippinensis species groups (Hymenoptera, Formicidae, Aenictinae)

Abstract The Southeast Asian species of the Aenictus javanus and Aenictus philippinensis groups are revised. Six species (four named and two new species) of the Aenictus javanus group occurring in this area are: Aenictus doydeei Jaitrong & Yamane, 2011, Aenictus duengkaei Jaitrong & Yamane, sp. n., Aenictus javanus Emery, 1896, Aenictus longinodus Jaitrong & Yamane, sp. n., Aenictus nishimurai Terayama & Kubota, 1993, and Aenictus piercei Wheeler & Chapman, 1930. Four species (three named and one new species) are recognized in the Aenictus philippinensis group: Aenictus pangantihoni Zettel & Sorger, 2010, Aenictus philippinensis Chapman, 1963, Aenictus punctatus Jaitrong & Yamane, sp. n., and Aenictus rabori Chapman, 1963. Aenictus piercei is removed from the members of the Aenictus piercei group sensu Jaitrong and Yamane (2011) and transferred to the Aenictus javanus group. Lectotypes and paralectotypes are designated for Aenictus piercei and Aenictus rabori. Size variation occurs among individuals from single colonies of the Aenictus javanus group, while the workers in the Aenictus philippinensis group are clearly monomorphic.


introduction
The genus Aenictus Shuckard, 1840 (subfamily Aenictinae) is one of the larger ant genera of the world. Curently 177 species and subspecies are listed (Bolton 2012).  established 12 species groups in the genus from the eastern part of the Oriental, Indo-Australian and Australasian regions, the groups being well defined on the basis of worker morphology.
The Aenictus javanus group is a small species group of the genus, defined by the following characteristics: antenna 10-segmented; mandible with 3 teeth including a large apical tooth; anterior margin of clypeus with several denticles; mesosoma in profile with dorsal margin almost flat. So far three species of the group, Aenictus doydeei lacking collar; antenna 10-segmented; antennal scape short, extending only half length of head; anterior clypeal margin roundly convex bearing 6-10 denticles; mandible subtriangular, masticatory margin with 3 teeth including the large apical tooth; frontal carina short, not extending beyond the level of posterior margin of torulus; parafrontal ridge absent; mesosoma in profile with dorsal margin almost flat; dorsal face of mesosoma meeting with lateral face at a right angle; propodeal junction angulated; propodeal declivity encircled with a thin rim. Subpetiolar process developed and triangular or subrectangular.
Head and first gastral segment entirely smooth and shiny except base of gastral tergite I and sternite I with dense small punctures. Body reddish brown to yellowish brown; typhlatta spot absent.
Remarks. This is a group of relatively small ants measuring 1.38-3.40 mm in total length. It is similar to the A. piercei group sensu  in terms of body size and coloration, but in the former the anterior clypeal margin has several denticles, while it lacks denticles in the latter.
A size variation exists among the specimens of single colonies. There is a general tendency that smaller specimens have a much weaker punctation, more elongate head and shorter antennal scape than larger specimens.

Checklist of species
Aenictus doydeei  Aenictus duengkaei Jaitrong & Yamane, sp. n. Aenictus javanus Emery, 1896 Aenictus longinodus Jaitrong & Yamane, sp. n. Aenictus nishimurai Terayama & Kubota, 1993 Aenictus piercei Wheeler & Chapman, 1930 Key to species based on the worker caste 1 Basal margin of mandible with a distinct denticle behind large basal tooth ( With head seen in profile occipital corner bluntly angulated (almost rightangled) (Java and Borneo) (Fig. 3D)  Description of worker (holotype and paratypes). Head in full-face view almost as long as broad, with sides convex and posterior margin almost straight or feebly concave; seen in profile occipital corner of head rounded. Antennal scape reaching midlength of head; antennal segment II longer and narrower than each of III-VI; terminal segment (X) about 2.5 times as long as broad. Anterior margin of clypeus bearing 9-10 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin lacking denticles. Mesosoma seen from above broader anteriorly than posteriorly; promesonotum laterally edged, in profile weakly convex dorsally and sloping gradually to propodeal junction; in profile propodeum slightly lower than promesonotum and almost flat dorsally; suture between mesopleuron and metapleuron completely absent; propodeal junction angulate, right-angled; declivity of propodeum shallowly concave, encircled by a thin rim. Petiole almost as long as high, its dorsal outline slightly elevated posteriorly; subpetiolar process well developed, subrectangular, its ventral margin almost straight and longer than posterior margin; postpetiole seen in profile subrectangular and slightly larger than petiole.
Head entirely smooth and shiny. Dorsal surface of pronotum smooth and shiny, lateral face superficially reticulate and shiny; mesothorax, metapleuron and propodeum densely microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for a small smooth and shiny area on dorsal surface.
Bionomics. The type series from Laos and three colonies from Thailand were collected from disturbed areas in the night. Thus A. doydeei is very probably nocturnal.  reported that this species preyed on Pheidole plagiaria.
Remarks. This species is closely related to Aenictus javanus, A. longinodus, and A. nishimurai in terms of body size and coloration. A. doydeei, however, is easily distinguished from A. javanus and A. longinodus as follows: occipital margin of head in profile rounded (Fig. 1E), while angled in A. javanus (Fig. 3D); petiole almost as long as high, but clearly longer than high in A. javanus and A. longinodus (Figs 3B,4B,D). A. doydeei is most similar to A. nishimurai, but is clearly larger than A. nishimurai with a slight overlap, and has the lateral face of the pronotum that is smooth but reticulated (almost smooth in A. nishimurai). A. doydeei is sympatric with A. nishimurai in Vientiane province, Laos and in northeastern Thailand. Description of worker (holotype and paratypes). Head in full-face view distinctly longer than broad and subrectangular, with sides weakly convex or almost parallel, and posterior margin clearly concave; seen in profile occipital corner of head rounded. Antennal scape very short, not reaching midlength of head; antennal segment II clearly longer than each of III-VI; III-VI shorter than broad; terminal segment longer than VII+VIII+IX and about 1.6 times as long as broad. Anterior margin of clypeus bearing 5-7 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin with 1-2 denticles behind large basal tooth. Mesosoma seen in profile almost flat dorsally; propodeal junction angulate; declivity of propodeum almost flat, with blunt lateral carinae, but not demarcated basally by a transverse carina. Petiole round almost as long as high; subpetiolar process well developed, subrectangular, its ventral border almost straight and longer than posterior border; postpetiole slightly smaller than petiole and its dorsal outline roundly convex.

Aenictus duengkaei
Head and antennal scape smooth and shiny; mandible extensively smooth but narrow zone along basal margin sculptured. Dorsal and lateral face of pronotum smooth and shiny except for anteriormost portion microreticulate; mesonotum smooth and shiny; mesopleuron superficially shagreened with smooth and shiny interspaces; metapleuron and propodeum shiny but microreticulate. Petiole entirely microreticulate but its dorsal face with a small area that is smooth (in larger specimens this area weakly sculptured). Postpetiolar node almost smooth and shiny. Head with relatively sparse standing hairs; mesosoma dorsally with relatively dense standing hairs mixed with sparse short hairs over the surface; longest pronotal hairs 0.07-0.10 mm long. Head, gaster and legs yellowish brown; mesosoma, petiole and postpetiole reddish brown; mandible darker than elsewhere.
Etymology. The specific name is dedicated to Dr. Prateep Duengkae of the Faculty of Forestry, Kasetsart University, who helped us in collecting material in eastern Thailand.
Bionomics. This species has been known only from eastern Thailand. The type series was collected from soil in a lowland dry evergreen forest (ca. 200 m), while the other colony (WJT04-E50) was collected from soil in an agricultural area. Thus, this species inhabits both primary and disturbed forests.
Remarks. Aenictus duengkaei is similar to A. piercei in terms of body size and coloration. Furthermore, the propodeal declivity is not margined basally with a carina in both species. However, A. duengkaei is easily separated from the latter by the condition of the mandible that has a distinct denticle on the basal margin, while the denticle is lacking in A. piercei. Description of worker (non-type workers from the type locality). Head in fullface view slightly longer than broad, subrectangular, with sides convex and posterior margin almost straight or feebly concave; seen in profile occipital corner of head angulated. Antennal scape reaching midlength of head; antennal segment II almost as long as each of III-V; terminal segment longer than VII+VIII+IX and 2.2 times as long as broad. Anterior margin of clypeus bearing 6-7 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin lacking denticles. Promesonotum in profile weakly convex dorsally or almost flat and sloping gradually to propodeal junction; in profile propodeum almost flat dorsally; suture between mesopleuron and metapleuron almost absent; propodeal junction angulate, right-angled; declivity of propodeum shallowly concave, encircled by a thin rim. Peti-ole distinctly longer than high, its dorsal outline slightly elevated posteriorly; subpetiolar process well developed, subrectangular, its ventral border almost straight or feebly concave and as long as posterior border; postpetiole almost as long as, its dorsal outline slightly convex.

Aenictus javanus
Head including antennal scape smooth and shiny; mandible striate along basal margin and smooth in apical and peripheral parts. Dorsal surface of pronotum smooth and shiny, lateral face of pronotum superficially reticulate but shiny; anteriormost part of pronotum microreticulate; mesothorax, metapleuron and propodeum microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for a small area on dorsal surface smooth and shiny.
Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs; longest pronotal hairs 0.15-0.18 mm long. Head yellowish brown to redish brown, mesosoma, petiole and postpetiole reddish brown; gaster yellowish brown. Typhlatta spot absent.  Six workers from Java (2 pins, three on each pin, labeled as typus) identified as A. javanus by Auguste-Henri Forel (MHNG) were examined. This series should be the same as that cited in Forel (1909). These workers are not the types.
Bionomics. All colonies of this species were collected from lowland rainforests.
Remarks. This species is closely related to Aenictus doydeei, A. longinodus, and A. nishimurai in terms of body size and coloration. Among these species is more closely related to A. longinodus than the others in having the long petiole. A. javanus can be separated from A. longinodus as follows: occipital margin of head in profile angulated, while rounded in A. longinodus; the lateral face of the pronotum that are reticulate but shiny (almost smooth in A. longinodus). Description of worker (holotype and paratypes). Head in full-face view slightly longer than broad, with sides convex and posterior margin almost straight; seen in profile occipital corner of head rounded. Antennal scape reaching midlength of head; antennal segment II longer and narrower than each of III-VI; terminal segment about 2 times as long as broad. Anterior margin of clypeus bearing 7 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin lacking denticles. Promesonotum seen in profile almost flat or weakly convex dorsally and sloping gradually to propodeal junction; in profile propodeum slightly lower than promesonotum and almost flat dorsally; propodeal junction angulate, right-angled; declivity of propodeum shallowly concave, encircled by a thin rim. Petiole longer than high, its dorsal outline convex; subpetiolar process well developed, subrectangular, its ventral margin almost straight or weakly convex and slightly longer than posterior margin; postpetiole seen in profile subrectangular and slightly shorter than petiole.

Aenictus longinodus
Head including antennal scape smooth and shiny; mandible striate along basal margin and smooth in apical and peripheral parts. Dorsal and lateral surface of pronotum smooth and shiny except for anteriormost part microreticulate; mesothorax, metapleuron and propodeum microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for a small smooth and shiny area on dorsal surface.
Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs over the surface; longest pronotal hairs 0.13-0.15 mm long. Head, mesosoma, petiole and postpetiole reddish brown; gaster yellowish brown and paler than the other parts of body; propodeum darkest. Distribution. Malay Peninsula (S. Thailand) (Fig. 7B).
Bionomics. The type series, two colonies from Ton Nga Chang Wildlife Sanctuary (N98-3 and N97-1), and a colony from Khao Luang National Park (TH03-WJT330) were collected in lowland rainforests. A colony (TH11-WJT-183) was collected from an open area in the day, while a colony (TH11-SKY-166), just coming out of soil, was from a disturbed forest near a concrete road in the night. Thus, this species inhabits both primary and disturbed forests and is active in the day and night.
Remarks Description of worker (paratype and non-type workers). Head in full-face view longer than broad, with sides slightly convex and posterior margin almost straight or feebly concave; seen in profile occipital corner of head rounded. Antennal scape reaching midlength of head; antennal segment II almost as long as broad; III-VIII each slightly broader than long; terminal segment 2.3 times as long as broad. Anterior margin of clypeus bearing 7-10 denticles. Masticatory margin of mandible with 3 acute teeth including a large apical tooth; basal margin lacking denticles. Mesosoma seen in profile weakly convex dorsally or almost flat; in profile propodeum almost flat dorsally; suture between mesopleuron and metapleuron absent; propodeal junction dully angulated, forming an almost right angle; declivity of propodeum shallowly concave, encircled by a thin rim. Petiole nearly as long as high, its dorsal outline convex; subpetiolar process well developed, subrectangular, its ventral margin nearly straight and longer than posterior margin; postpetiole seen in profile almost as long as petiole, with round node. Head including antennal scape entirely smooth and shiny; mandible finely striate with outer zone smooth and shiny. Dorsal and lateral surface of pronotum smooth and shiny except for anteriormost part microreticulate; mesothorax, metapleuron, and propodeum microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for smooth and shiny area on dorsal surface.
Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs; longest pronotal hairs 0.15-0.18 mm. Head yellowish brown; mesosoma, petiole and postpetiole reddish brown; gaster yellowish brown, but paler than head.
Non Distribution. Vietnam, Laos and Thailand.

Bionomics.
No biological information is available for A. nishimurai. However, judging from the localities cited above this species is distributed from lowland to highland (200-1,500 m) and inhabits primary, secondary and disturbed forests.
Remarks Description of worker (lectotype, paralectotype and a non-type worker). Head in full-face view slightly longer than broad, subrectangular, with sides feebly convex and posterior margin almost straight; seen in profile occipital corner of head rounded. Antennal scape reaching midlength of head; antennal segment II longer and narrower than each of III-VI; terminal segment almost as long as VII+VIII+IX and 1.9 times as long as broad. Anterior margin of clypeus bearing 9-10 denticles (this observation is based on the single non-type worker, since in the lectotype mouth parts are buried in glue and the head of the paralectotype was missing). Masticatory margin of mandible with 3 acute teeth including large apical tooth; basal margin lacking denticles. Promesonotum in profile almost flat dorsally; in profile propodeum almost flat dorsally; propodeal junction angulate, right-angled; declivity of propodeum nearly flat, with blunt lateral carinae, but not demarcated basally by a transverse carina. Petiole almost as long as high, its dorsal outline convex; subpetiolar process well developed, subrectangular, its ventral margin slightly convex and longer than posterior margin; postpetiole almost as long as petiole.
Head including antennal scape entirely smooth and shiny. Mandible finely striate except along masticatory and outer margins. Pronotum entirely smooth and shiny except for anteriormost part microreticulate; mesonotum smooth and shiny; mesopleuron, metapleuron and propodeum microreticulate. Petiole entirely microreticulate. Postpetiole microreticulate except for a small smooth and shiny area on dorsal surface.
Head and mesosoma dorsally with relatively sparse standing hairs mixed with sparse short hairs; longest pronotal hairs 0.09-0.10 mm long. Entire body yellowish brown or reddish brown; legs palest.
Non-type material examined. We examined a worker collected from the same place by Chapman but in a different year (2/6/29). It bears a small piece of white paper with handwriting "cotype", and a small piece of red paper. As this specimen was not mentioned in the original description, it is not part of the type series. However, all the three specimens belong to the same species without doubt.

Bionomics.
Little is known about the bionomics of A. piercei. Nothing is mentioned by Wheeler (1930) on it. However, judging from the hitherto known localities (Negros and Mindanao) (see Wilson 1964) this species inhabits lowland (15-600 m) and is probably restricted to the Philippines. Wilson (1964) cited India, Solon (ca. 1400 m), as a locality of A. piercei, but the identification should be reconfirmed.
Remarks. This species is most similar to A. duengkaei (see under A. duengkaei for differences). According to Wilson (1964) the clypeus of A. piercei has an entire anterior margin without denticles. Following this information, Jaitrong and Yamane (2011) treated A. piercei as a member of their Aenictus piercei group (no denticles in this group). However, the non-type specimen mentioned above has nine denticles on the anterior clypeal margin. After carefully examining the type material of A. piercei we concluded that this species should be removed from the A. piercei group and that it is a member of the A. javanus group.

Revision of the Aenictus philippinensis group
Aenictus philippinensis group Diagnosis.  defined this species group as follows: antenna 10-segmented; scape not reaching the posterolateral corner of head; anterior clypeal margin convex in the middle, lacking denticles; mandible triangular, very densely with punctures; its masticatory margin with a large and sharp apical tooth followed by 6-8 small inconspicuous denticles; basal margin lacking denticles; frontal carinae fused at the level of antennal base to form a single carina, extending less than half length of head, and well developed anteriorlly and poorly developed posteriorly; parafrontal ridge present, not reaching midlength of head; occipital margin forming a collar or carina; mesosoma in profile with promesonotum convex dorsally and sloping gradually to metanotal groove; mesopleuron clearly demarcated from metapleuron by a deep groove and from promesonotum by a distinct carina; metanotal groove relatively deep and distinct; propodeal junction angulated; declivity of propodeum concave, encircled with a rim; subpetiolar process weakly developed.
First gastral segment entirely smooth and shiny except the base of both tergite and sternite with dense small punctures. Body reddish brown to dark brown; typhlatta spot absent.
Remarks. This group consists of relatively large species measuring 4.05-4.60 mm in total body length, and is closely related to the A. pachycerus group and A. hottai group. However, the A. philippinensis group is separated from the other two by the mesonotum demarcated from the mesopleuron by a conspicuous ridge and the metanotal groove relatively deep and distinct. The sculpture of the head is variable, from entirely smooth to densely puncto-reticulate (see .
Worker caste is clearly monomorphic.

Check list of species
Aenictus pangantihoni Zettel & Sorger, 2010 Aenictus philippinensis Chapman, 1963 Aenictus punctatus Jaitrong & Yamane, sp. n. Aenictus rabori Chapman, 1963 Key to species based on the worker caste Description of worker (paratypes). Head in full-face view slightly longer than broad, with sides slightly convex and posterior margin almost straight; occipital margin forming a distinct carina; seen in profile occipital corner of head rounded. Antennal scape relatively short, slightly extending 2/3 of head length; antennal segment II slightly longer than each of III-VI; terminal segment almost as long as VII+VIII+IX. Frontal carinae short fused at the level of antennal base to form a single carina and slightly extending beyond the level of the posterior margin of torulus, poorly developed in posterior half. Parafrontal ridge short, extending less than 1/3 of head length, 0.17 mm long, seen in profile weakly developed in the middle. Masticatory margin of mandible with a large apical tooth followed by a series of 7-9 denticles of two sizes, the larger ones alternating with 1-3 of smaller size. Mesosoma in profile with promesonotum weakly convex dorsally and sloping gradually to metanotal groove; metanotal groove distinct and deep; upper portion of mesopleuron impressed; propodeum slightly lower than mesonotum; propodeal junction right-angled; declivity of propodeum shallowly concave, encircled with a distinct rim. Petiole subsessile, distinctly longer than high; subpetiolar process almost absent; postpetiole as long as petiole (including short pedicel) and almost as long as high, with its node rounded dorsally. Legs relatively short, seen from side with greatly swollen femora.
Head entirely smooth and shiny, except for hair pits; mandible smooth and shiny, with scattered punctures; antennal scape superficially shagreened. Pronotum smooth and shiny except for its anteriormost portion reticulate; lateral face of pronotum smooth and shiny, with a narrow ventral belt that is impressed and reticulate, this belt continuing posteriorly, running along posterior margin of the lateral face, approaching dorsal face of pronotum; mesonotum smooth and shiny; mesopleuron, metapleuron and propodeum densely punctuate/reticulate and mat except for isolated small shiny areas. Both petiole and postpetiole microrecticulate except dorsal faces smooth and shiny. Femora superficially shagreened with smooth and shiny interspaces; tibiae superficially shagreened, partly smooth and shiny. Head and mesosoma dorsally with relatively sparse standing hairs; longest pronotal hair 0.2-0.25 mm long. Entire body reddish brown.
Distribution. Philippines (Camiguin Island) (Fig. 12). Bionomics. So far A. pangantihoni is known only from the type locality. The type material was collected from a trail lined with some bushes and trees in a pasture area at an elevation ca. 350 m (Zettel and Sorger 2010).
Remarks. A. pangantihoni is most similar in general appearance to A. rabori. However, it is easily distinguished from the latter as follows: smaller than A. rabori ; seen in profile occipital corner of head round, without protruding lobe (with a lobe in A. rabori); sides of head entirely smooth and shiny (partly superficially shagreened with smooth and shiny interspaces in A. rabori). Types. Syntype workers from Philippines, Negros, Horns of Negros, 450 and 1,080 m (MCZC). We did not examine the type material of this species but specimens of a single colony from the type locality (Philippines, Negros) were examined.
Description of worker. Head in full-face view subretangular, slightly longer than broad, with sides weakly convex and posterior margin almost straight; occipital margin forming a narrow carina; seen in profile occipital corner of head rounded. Antennal scape relatively short, reaching only 2/3 of head length; antennal segment II almost as long as each of III-VI; terminal segment almost as long as VII+VIII+IX. Frontal carinae fused at the level of antennal base to form a single carina and extending beyond the level of the posterior margin of torulus, poorly developed in posterior half. Parafrontal ridge relatively long, extending less than 1/3 of head length, 0.25-0.28 mm long. Masticatory margin of mandible with a large apical tooth followed by a series of 6-7 denticles of same size. Mesosoma in profile with dorsally convex promesonotum and sloping gradually to metanotal groove; metanotal groove distinct and deep; mesopleuron relatively short, clearly dermacated from metapleuron by a deep groove; propodeum lower than mesonotum, weakly convex dorsally; propodeal junction right-angled; declivity of propodeum shallowly concave, encircled with a distinct rim. Petiole subsessile, slightly longer than high; subpetiolar process very low, its anteroventral corner bluntly angulate; postpetiole slightly longer than petiole and slightly longer than high, with its dorsal outline convex. Legs relatively long with apical halves of femora and tibiae somewhat swollen.
Head superficially reticulate and shiny; mandible very finely striate except along masticatory margin; antennal scape superficially shagreened. Promesonotum finely macroreticulate except dorsal face largely smooth and shiny; mesopleuron, metapleuron, and propodeum densely punctate/reticulate. Both petiole and postpetiole punctate except dorsal face of the latter smooth and shiny. Femora entirely superficially reticulate and shiny, partly smooth and shiny; tibiae weakly punctate.
Head and mesosoma dorsally with relatively sparse standing hairs mixed with short hairs over surface; longest pronotal hair 0.17-0.20 mm long. Entire body reddish brown.

Bionomics.
A. philippinensis is very probably restricted to the Philippines and probably sympatric with A. rabori in at least Negros Oriental. Wilson (1964) cited the observation by Chapman: "the workers of a colony came from the hole in the ground, climbed up a nearby stump, and spent the next hour in which they were observed building a living pyramid in the center of the stump. Some tried to build out from the edge of the stump in a horizontal direction." We found a colony under a stone near a road.

Remarks.
A. philippinensis is similar to A. punctatus as they have sculptured head and mandible. However, they differ in some characters. The sculpturing on the head is much weaker in A. philippinensis (superficially reticulate and shiny) than in A. punctatus (finely punctate). Pronotal dorsum is smooth and shiny in A. philippinensis, but finely punctate in A. punctatus. Propodeal declivity is dorsally margined with a low rim in A. philippinensis; the rim is much more developed, in profile distinctly protruding posteriad in A. punctatus. Description of worker (holotype and paratypes). Head in full-face view elliptical, clearly longer than broad, with sides convex and posterior margin almost straight or weakly convex; occipital margin forming a distinct carina; seen in profile occipital corner of head rounded. Antennal scape relatively long, extending 3/4 of head length; antennal segment II almost as long as each of III-VI; terminal segment slightly shorter than VII+VIII+IX. Frontal carinae short fused at the level of antennal base to form a single carina and slightly extending beyond 1/4 of head length, poorly developed in posterior half. Parafrontal ridge short, extending less than 1/3 of head length, 0.30-0.33 mm long. Masticatory margin of mandible with a series of 6-7 denticles of same size; basal margin of mandible lacking denticles. Mesosoma in profile with promesonotum convex dorsally and sloping gradually to metanotal groove; metanotal groove indistinct compared with those of the other members of the group; mesonotum demarcated from mesopleuron by a conspicuous ridge. Propodeum almost flat or weakly convex dorsally; declivity of propodeum shallowly concave, encircled with a developed rim; seen in profile dorsal portion of the rim protruding posteriad. Petiole subsessile, slightly longer than high, its dorsal outline elevated posteriorlly; subpetiolar process very low, its ventral outline weakly convex; postpetiole longer and larger than petiole and slightly longer than high, with its dorsal outline convex. Legs relatively long with apical halves of femora and tibiae somewhat swollen.

Aenictus punctatus
Head entirely finely punctate; mandible very finely striate except along masticatory margin; antennal scape finely punctate. Pronotum entirely punctate; mesopleuron, metapleuron and lateral face of propodeum punctate; dorsal face of propodeum finely punctate. Petiole entirely punctate; postpetiole punctate with weakly sculptured and shiny anterior slope of node. Basal half of femora densely punctate but apical half superficially macroreticulate and shiny; tibiae macroreticulate and shiny.

Types.
Nine syntype workers (two on each of three pins, three on another) from Philippines, Negros, Horns of Negros, 1,080 m (MCZC, examined). One worker among them (top on a pin) is selected as lectotype (Fig. 11E) Description of worker (lectotype and paralectotypes). Head in full-face view slightly longer than broad, with sides convex and posterior margin nearly straight, Figure 11. Aenictus rabori (lectotype). A Head in full-face view B habitus in profile C occipital corner of head D dorsal view of body e lectotype and paralectotype designated in the present paper (arrow indicating the lectotype) F labels of lectotype. very weakly sinuate; occipital margin bearing a distinct carina; occipital corner of head with a protruding lobe (part of occipital carina). Antennal scape relatively short, reaching only 2/3 of head length; antennal segment II slightly longer than each of III-VI; terminal segment slightly shorter than VII+VIII+IX. Frontal carinae short fused at the level of antennal base to form a single carina and much extending beyond the level of the posterior margin of torulus, poorly developed in posterior half. Parafrontal ridge short, extending less than 1/3 of head length, 0.25-0.27 mm long, seen in profile weakly developed in posterior half. Masticatory margin of man-dible with a large apical tooth followed by a series of 4-5 denticles, which gradually reduce in size toward basal angle of mandible. Promesonotum in profile weakly convex dorsally and sloping gradually to metanotal groove; metanotal groove distinct and deep; upper portion of meso-and meta-pleuron impressed, much lower than promesonotum. Declivity of propodeum shallowly concave, encircled with a distinct rim that protrudes posteriad. Petiole subsessile, distinctly longer than high; subpetiolar process almost absent; postpetiole slightly shorter than petiole and almost as long as high, with its node rounded dorsally. Legs relatively short, seen from side with greatly swollen femora.
Head entirely smooth and shiny, except for hair pits, area on the side of head anterior to occipital corner with superficial reticulation; mandible extensively smooth and shiny except for hair pits; antennal scape superficially shagreened. Pronotum smooth