Aenictus currax Emery

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 : 13-15

Aenictus currax Emery

( Figs. 11–12 )

Aenictus currax Emery, 1900: 310 , pl. 8, fig. 1; Wilson, 1964: 459, figs. 23, 86; Bolton, 1995: 59.

Types. One syntype worker from NE New Guinea, Astrolabe Bay, Erima (MCSN) was examined and selected as the lectotype.

Measurements. Worker lectotype: TL 4.15 mm; HL 0.88 mm; HW 0.70 mm; SL 0.73 mm; ML 1.33 mm; PL 0.30 mm; CI 80; SI 104.

Redescription of worker (lectotype and non-type specimens). Head in full-face view distinctly longer than broad, with sides slightly convex and posterior margin feebly concave; occipital margin bearing a distinct carina. Antenna relatively thick; scape not reaching posterolaterial corner of head; antennal segments II–X each longer than broad, but V–VIII rather short; II slightly longer than each of III–VI. Frontal carina short, slightly extending beyond the level of posterior margin of torulus. Parafrontal ridge short. Masticatory margin of mandible with a large apical tooth followed by a medium-sized subapical tooth and 4–6 denticles; basal margin of mandible sinuate with 3–4 ill-defined denticles. Mesosoma elongate; promesosoma in profile convex dorsally and sloping gradually to metanotal groove; mesopleuron clearly demarcated from metapleuron by a groove. Propodeum in profile with moderately convex (in smaller specimens almost flat) dorsal outline; propodeal junction obtusely angulate; declivity of propodeum shallowly concave and encircled with a thin rim; area below propodeal spiracle distinctly impressed; distance between propodeal spiracle and metapleural gland bulla almost as long as spiracular diameter; the spiracle clearly circular, in diameter about 2.5 times as long as postpetiolar spiracle. Petiole distinctly longer than high, with its dorsal outline convex; subpetiolar process reduced, low, anteriorly right-angulate. Postpetiole round, almost as long as high.

Head including mandible and antennal scape extensively smooth and shiny; basal 1/3 of scape superficially sculptured. Pronotum smooth and shiny except for the anteriormost portion which is punctate; mesonotum smooth and shiny; mesopleuron macroreticulate, with several short longitudinal rugulae; propodeum bearing scattered, thin, straight longitudinal rugae, whose interspaces are smooth and shiny. Petiole smooth and shiny dorsally, its anterior portion, lateral faces and posterior portion punctate. Postpetiole entirely smooth and shiny except for anteriormost portion which is punctate. Legs smooth and shiny.

Body with relatively sparse standing hairs; longest pronotal hair 0.23–0.25 mm long. Entire body brownishyellow except for a much darker median area from upper frons to vertex between large typhlatta spots occupying the occipital corner; basal 1/3 of antennal scape also darker.

Non-type material examined. Papua New Guinea: Madang, Haya Village, 26 II 2009, H. O. Tanaka leg. ( SKYC, THNHM).

Distribution. Papua New Guinea.

Bionomics. Wilson (1964) reported that a colony of A. currax was found in Karima, Papua New Guinea, the morning of March 1955, on the open floor of a virgin lowland rainforest. It consisted of a packed mass of workers, which must have numbered at least 100,000. The workers extended up the tree trunk to about 1 m. The colony was apparently entirely above ground, and the workers were carrying bodies of adult workers and males of the ant genus Crematogaster . This species is very probably restricted to New Guinea.

Remarks. Aenictus currax is very similar in general appearance to A. diclops , A. huonicus , A. pfeifferi , A. parahuonicus , and A. wayani . Among these this species is more closely related to A. diclops and A. wayani than to the others in having a slender mesosoma and relatively long antennal scape (SI 97–104, while SI is less than 95 in A. pfeifferi , A. huonicus , and A. parahuonicus ). Aenictus currax can be separated from A. diclops by having the propodeal and petiolar dorsa smooth and shiny (entirely sculptured in A. diclops ), and it is easily distunguished from A. wayani as follows: antennal scape relatively longer (SI 104 in A. currax , 97–100 in A. wayani ); basal margin of mandible sinuate with 3–4 ill-defined denticles in A. currax (denticles absent in A. wayani ). All the species mentioned above are completely allpatric, but A. gracilis is sympatric with A. pfeifferi in Borneo and A. parahuonicus in Thailand etc.

The workers from Haya Village, Madang, Papua New Guinea are on average smaller than the lectotype from Astrolabe Bay.

Figures

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.