Colobopsis badia

A canopy nesting species that is a member of the Colobopsis cylindrica group, a set of species that employ a novel defensive strategy. Minor workers of these so called exploding ants will, when threatened, flex their gasters so hard that they rupture. This releases a toxic chemical mixture that they then attempt to smear on their antagonists.

Identification
A member of the Colobopsis cylindrica group.

Laciny et al. (2018) - The male of Colobopsis badia can be distinguished from males of Colobopsis explodens by larger body size, differing colour pattern, more shiny integument, well-developed clypeal carina, differing proportions of wing venation, and relatively shorter scapes. In the genitalia, the most striking differences are in the narrower gonostylus and the more rounded digitus apex.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore. Oriental Region: India.

Biology
Zettel et al. (2018) examined foraging ecology of this species and Colobopsis leonardi. Workers of a C. badia colony were observed on leaves of low vegetation and on lianas leading up to two small trees (Figure 2). Nest entrances were not found; they were most probably located higher up in the tree, as is often the case in COCY colonies. Feeding experiments were carried out on June 6, at around 10:30 a.m. when a moderately high activity of workers (higher than on the previous and following days) was observed on an ant trail on a ca. 2 cm thick liana ca. 0.5 m above ground. As a preliminary feeding experiment, three freshly killed specimens of Coptotermes curvignathus termites were placed on the liana at a distance of ca. 5 cm from each other. Workers approaching this area shrunk back without touching the C. curvignathus specimens and/or alarmed nest mates with highly raised gasters. The area was subsequently avoided by most (not all) workers which then used a liana running parallel to the first one. During the time of observation, a C. badia worker was observed carrying a small item. Worker and item were caught and preserved. The item was a very small male ant (presumably Dolichoderinae).

Nomenclature

 *  badia. Formica badia Smith, F. 1857a: 54 (w.) SINGAPORE. Viehmeyer, 1916a: 161 (m.). Combination in Camponotus: Roger, 1863b: 3; in C. (Colobopsis): Forel, 1913k: 133. [Unresolved junior primary homonym of Formica badia Latreille, 1802c: 238 (now in Pogonomyrmex (Bolton, 1995b: 87).] Current subspecies: nominal plus saginatus. Combiniation in Colobopsis: Ward, et al., 2016: 350.

Worker
Laciny et al. (2018) - Lectotype Minors: TL 6.13; HW 1.51; HL 1.63; HS 1.57; PS5 n.a.; PS6 n.a.; EL 0.40; SL 1.43; SW 0.15; ML 1.96; HaL 0.17; PH 0.54; PL 0.36; NH 0.32; FeL 2.22. Indices: CI 93; SI 95; SWI 10; EI 26; PI 150; FeI 147; PSI n.a. Paralectotype Minors: (n = 2): TL 6.13, n.a.; HW n.a., 1.36; HL n.a., 1.52; HS n.a., 1.44; PS5 n.a., 0.21; PS6 n.a., 0.25; EL 0.36, 0.37; SL 1.39, 1.40; SW 0.12, 0.13; ML 1.89; HaL 0.13, n.a.; PH n.a., 0.51; PL 0.37, 0.42; NH 0.27; FeL 2.15. Indices: CI n.a., 89; SI n.a., 103; SWI 8, 9; EI n.a., 27; PI n.a., 121; FeI n.a., 158; PSI n.a., 32. *One specimen with strongly damaged head, one with missing gaster. Non-type minor: (n = 10): TL 5.64–6.23; HW 1.46– 1.59; HL 1.63–1.72; HS 1.54–1.65; PS5 0.24–0.25 (3); PS6 0.24 (3); EL 0.38–0.40; SL 1.37–1.43; SW 0.13–0.14; ML 1.96–2.22; HaL 0.13–0.19; PH 0.51–0.56 (7); PL 0.41–0.45; NH 0.31–0.37 (9); FeL 2.09–2.28. Indices: CI 88–92; SI 90–96; SWI 9–10; EI 25–27; PI 118–130 (7); FeI 141–148; PSI 30–31 (3).

Male
Laciny et al. (2018) - Notes on collecting and identification: A single male collected at light was identified as a specimen of the Colobopsis cylindrica group. DNA barcoding revealed specific identity with a nest series of Colobopsis badia from the same botanical garden. The morphological identification of this nest series (Col. 66-4) was carried out by direct comparison to the lectotype of Colobopsis badia. Overall very similar to Colobopsis explodens and differing by the following characters: TL 8.28; HW 1.35; HL 1.26; HS 1.30; PS5 0.20; PS6 0.15; EL 0.48; SL 0.83; SW 0.10; ML 3.07; HaL n.a.; PH 0.47; PL 0.41; NH 0.31; FeL 1.96; OcW 0.19; OED 0.29; OcD 0.46; FWL 7.43; MSW 1.37; 2r 0.41; 4Rs+M 0.37. Indices: CI 107; SI 61; SWI 13; EI 36; PI 116; FeI 145; PSI 26; OI 61; Structures: Size larger (TL ca. 8.3 mm). Integument rather shiny (Fig. 10a, b), especially on mesosoma. Clypeus with distinctly developed median carina, almost reaching anterior margin. Maxillary palpi (PSI 26) and antennal scapes (SI 61) relatively short. First funicular segment slightly more enlarged (30% wider than the following segment, Fig. 10a). Vein 4Rs+M of forewing long. Petiolar node slightly more widely rounded in lateral aspect. Genital structures: very similar to Colobopsis explodens, with the following exceptions: Gonostylus very narrow, with weaker reticulation of lateral surface. Basivolsella with extremely short ventral setae. Digitus with rounded apex, without ventroapical corner. Valviceps with slightly coarser ventral serration. Colour: Head chiefly dark brown, with lighter area comprising frons between antennal insertions and clypeus. Eyes grey. Ocelli clear, almost colourless. Posterior and anterior clypeal margins, as well as proximal fourth of clypeal carina black. Gaster dark brown. Mesosoma, petiole, mandibles, antennae, and legs lighter brown, appendages becoming yellowish towards apices. Antennal insertions, mandibular bases, margins of thoracic sclerites (especially below tegulae) creamy yellow. Gastral tergites medially with very narrow hyaline margins; sternites with relatively broad posterior margins. Wings hyaline, forewing with a slight brownish tinge and cells along veins, as well as pterostigma darker brownish, all veins pale brown. On hind wing all veins pale yellow. Pilosity: Appressed and subdecumbent setae comparatively shorter and sparser, but difference less obvious on gaster. Standing setae on mesonotum and gaster shorter, on mesonotum less numerous.

Type Material
Formica badia

Three worker syntypes in. One labelled “Sing. 6,” two labelled “Sar. 32.” Smith records both localities in the original description. There is also a single worker from Sumatra, det. as badia by Smith.

Laciny et al. (2018) - 1 lectotype minor worker, present designation), Singapore, “Formica badia”, “Syntype”, CASENT 0901897, “Lectotypus Formica badia Smith, 1857 des. Laciny & Zettel, 2017”, 2 paralectotype minor workers (Oxford University Museum of Natural History) mounted on the same card, Sarawak (“Sar 32”), “Formica badia”, “Syntype”, “Paralectotypes Formica badia Smith, 1857”.

Lectotype: Minor worker glued to a square cardboard, in relatively good condition; right hind leg missing; tarsi of middle legs and left hind leg broken; erect setae on dorsum probably lost. Structures agree well with other species of the Colobopsis saundersi complex, a few characteristic features are given: Setae on scape more decumbent than in Colobopsis explodens. Dorsal outline of mesosoma almost straight, only with weak indentation at meso-metanotal suture. Propodeum forming a distinct obtuse angle in lateral view. Petiolar node relatively short, apex acute in lateral view, its crest slightly indented in middle. Tergites I–III with very fine, strongly transverse microsculpture (lateral parts not visible). Colour relatively dark brown; appendages strongly infuscate; antennal segments III–XII, meso- and metafemora almost black.

Paralectotypes: Two minor workers glued to the same square cardboard, in relatively poor condition. Left specimen with damaged head and gaster, lacking right middle leg; major parts of body covered by dirt or glue; most erect setae probably lost. Right specimen with slightly damaged head, lacking gaster and right hind leg; some parts of body covered by dirt or glue; most erect setae probably lost. The two specimens are probably conspecific, but conspecificity with the lectotype is uncertain. The combination of morphological features is intermediate between Colobopsis badia and Colobopsis explodens: setae on scape similar to Colobopsis explodens, more erect than in the lectotype; dorsal outline of mesosoma intermediate, more structured than in the lectotype, but propodeum with angle; shape of node intermediate, apex more acute than in Colobopsis explodens. Colour almost as dark as in the lectotype.