Camponotus micragyne

A Weaver Ant that uses silk in its nest construction.

Identification
A member of the subgenus Karavaievia. This group of Camponotus species is known for their monomorphic workers and their nest weaving behavior.

Dumpert (1995) - C. micragyne workers are similar to Camponotus gentingensis, Camponotus asli and Camponotus belumensis because of their similar light (yellowish) colour. C. gentingensis is the darkest and largest of these species and can easily be distinguished from the remaining three species because of their opaque cuticle of all body parts. The cuticles of C. micragyne, C. asli and C. belumensis are considerably shining. Compared with C. belumensis, the workers of C. micragyne are significantly larger. Compared with C. asli, the heads of C. micragyne are significantly wider. The females of C. micragyne can easily be distinguished from all other Karavaievia females by the considerably smaller length of their bodies (TL 7.9). TL of all other Karavaievia females ranges between 9.6 and 11.5.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia.

Biology
Dumpert et al. (2006) - In North Sumatra (Ketambe, G. Leuser National Park) we found a huge colony (> 100 pavilions) of C. micragyne which shared some of its pavilions with a Monomorium species. Beside “typical” Karavaievia nest pavilions located under leaves and made with the help of larval silk, the colony occupied partly the nest pavilions of the Monomorium species. Altogether we found three types of nest pavilions in this Karavaievia colony, in close proximity to one another, even on the same leaf:

(I) Wide, oval shaped nest pavilions (max. length: 10 cm, width: 5 cm, height: 1.5 cm), made mainly from larval silk riddled with relatively coarse wooden particles and inhabited only by C. micragyne.

(II) Narrow, tube shaped nests (max. length: 9 cm, width: 1.5 cm, height: 1.5 cm), built laterally on nerves of leaves, made from fine plant trichomes derived from the nest leaves, with only the inner surface of the nest walls covered (irregularly) with silk. Inhabited solely by C. micragyne (workers, alates, brood).

(III) Same architecture as type (II), however, colonized by C. micragyne workers with brood and alate females and additionally by the Monomorium species (queen, workers, brood). Though silk was used for covering the inner surfaces of walls, these nests were not divided into separate chambers. Both species were aggregated on opposed sides of the nest without any sign of aggressiveness. Only when nest inhabitants were heavily disturbed by us, did one observe aggressive behavior of Monomorium sp. against C. micragyne, which lasted, however, less than one minute.

General details about the biology of species in this subgenus can be found on the Karavaievia webpage.

Nomenclature

 *  micragyne. Camponotus (Karavaievia) micragyne Dumpert, in Dumpert, Maschwitz, et al. 1995: 99, figs. 5, 6 (w.q.m.) WEST MALAYSIA.

Worker
Holotype. TL 4.3, HL 1.1, HW 1.2, CI 112, SL 1.28. SI 97, PW 0.73, OD 0.3. Paratypes: TL 4.0 ± 0.15 (standard deviation), HL 1.24 ± 0.08), HW 1.33 ± 0.09, CI 107 ± 1.6, SL 1.34 ± 0.07, SI 99.1 ± 1.8, PW 0.80 ± 0.04, OD 0.34 ± 0.02 (7 measured).

Head trapezoidal and wider than long (CI 112); occipital corners strongly rounded, occipital margin slightly concave, head sides strongly convex. More than in most other Karavaievia species and similar to Camponotus gombaki. Eyes are situated behind the midlength of the sides of the head: their maximum diameter is 0.3 mm. or abour 0.25 HW. Frontal carinae are slightly divergent and extend to about midlength of head. Anterior clypeal margin straight. Mandibles shorter than in most other Karamievia species as Camponotus nigripes, C. asli, Camponotus orinus, C. gentingensis, C. belumensis and Camponotus striatipes. They are distinctly rounded on outside and with 5 subequal teeth on inside. Frontal area not clearly delimited from neighbouring head parts and as much shining.

Alitrunk with a deep impression between promesonotum and propodeum, and two raised stigmata at the deepest point of the impression. Propodeum in profile strongly rounded and. higher than promesonotal dorsum. Dorsal part of promesonotal dorsum flatter than descending part. Petiolar scale triangular in profile, with a broad base tapering towards the apex into a narrow ridge. Petiolar apex, seen from above, pointed.

Body uniformly yellowish brown; alitrunk with alternating lighter and darker rings. Cuticle of head, alitrunk and gaster shining. Decumbent pubescence nearly lacking. Longer erect and suberect hairs distributed over the whole body.

Queen
Gynetype: TL 7.0, HL 1.85, HW2.03, CI 109, SL 1.75, SI 115, PW 1.68, OD 0.63 (alate female).

Head slightly broader than long (CI 109); sides of the head straight, occipital corners rounded, occipital margin concave. Frontal carinae extend about to midlength of the head. Apart from a lateral projection beyond the scapal insertion, they are almost straight and only slightly divergent. Eyes are situated behind the midlength of the sides of the head and relatively large (0.31 x HW). Clypeus - as in all other Karavaievia females - with a median semicircular excision at its anterior margin. Mandibles strong. distinctly rounded on outside, and with 5 subequal teeth on inside.

Body uniformly dirty yellowish brown with darker front parts of the head and rings of darker brown colour on the gastral tergites. Cuticle structure of head, alitrunk and gaster shining. Wings whitish, veins yellow brown. Body covered with yellowish white decumbent pubescence; longer erect, yellowish white hairs are particularly dense on clypeus, but also on rest of body, including scapes and legs. Petiolar profile with broader base, which tapers to a transverse ridge. Petiolar ridge rounded when seen from above or behind.

Male
Allotype: TL 4.1, HL 0.83, HW 0.95, CI 115, SL 0.95, SI 86, PW 1.23, OD 0.53.

The trapezoidal head is wider than long (CI 115), with prominent convex eyes, extending to the upper end of the head sides. Occipital margin strongly convex with protruding ocelli. Clypeus nearly half as high than wide with straight anterior clypeal margin. Mandibles with only one apical tooth. Frontal carinae sinuate, reaching back to upper end of the eyes. Eyes very large; maximum diameter 0.53, or about 0.56 HW. Scapes long, projecting beyond occipital margin of the head by about half their length. Pedicel expanded at its distal end and thicker than following flagellar segments.

Propodeal profile rounded, with weakly convex dorsal and weakly concave descending part. Petiolar scale triangular in profile, with a broad base tapering equally from front and behind to a ridge. Ridge with a deep median excision.

Body uniformly dark brown with the exceptions of the dirty yellow brown frontal head parts (including the mandibles) and the likewise lighter coloured flagella and tarsi. All body parts are shining and showing densely arranged strong punctures under the dissecting microscope. Wings whitish with yellowish veins. Decumbent pubescence on whole body; longer erect and subtract hairs not very dense on head, alitrunk and gaster.

Type Material
Holotype worker, Peninsular Malaysia, Belum/Perak, primary rain forest 320 m above sea level, March/2/1994 A. Weissflog leg. (Naturhistorisches Museum, Basel).

Paratypes: 7 workers with same data as holotype (1 in Museum of Comparative Zoology at Harvard University; 1 Forest Research Institute of Malaysia in Kepong; 1 in Museo Civico di Storia Naturale, Genova; 4 in collection of the author).

Gynetype queen, Peninsular Malaysia, Belum/Perak, primary rain forest 320m above sea level, March/2/1994 A. Weissflog leg. (Naturhistorisches Museum, Basel).

Allotype male. Peninsular Malaysia, Belum/Perak, primary rain forest 320 m above sea level, March/2/1994 A. Weissflog leg. (Naturhistorisches Museum, Basel).

Etymology
The name is derived from the fact that the females of this species are considerably smaller than those of all other yet known Karavaievia species.

References based on Global Ant Biodiversity Informatics

 * Dumpert K., U. Maschwitz, and A. Wesissflog. 2006. Description of five new weaver ant species of Camponotus subgenus Karavaievia EMERY, 1925 (Hymenoptera: Formicidae) from Malaysia and Thailand, with contribution to their biology, especially to colony foundation. Myrmecologische Nachrichten 8: 69-82.