Camponotus darlingtoni

An ant of the south-west corner of WA, where it can be found in woodland around Perth and on Rottnest Island (Heterick 2009).

Identification
McArthur (2008), discussing the junior synonym Camponotus christmasensis: A member of the C. claripes group (McArthur 2007a), a close relative of Camponotus insipidus (as C. minimus). Both lack erect setae on the underside of the head and have wide frontal carinae. Compared with C. insipidus, the integument of this species is more finely and sharply striate. Compared with Camponotus fraseri it lacks short sloping distinctive setae on the scapes.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 * . Camponotus (Myrmophyma) darlingtoni Wheeler, W.M. 1934d: 160 (s.w.q.) AUSTRALIA (Western Australia, Western Australia: Rottnest I.) (date of publication: 5.x.1934).
 * Junior synonym of testaceipes: Brown, 1956a: 39; Taylor, 1987a: 15; Bolton, 1995b: 95.
 * Status as species: McArthur, Adams & Shattuck, 1998: 595; McArthur, 2007a: 331; Heterick, 2009: 70; McArthur, 2014: 120.
 * Senior synonym of rottnesti (unnecessary replacement name): Brown, 1956a: 39; McArthur, 2007a: 296.
 * rottnesti. Camponotus (Myrmophyma) rottnesti Donisthorpe, 1941k: 239.
 * Junior synonym of testaceipes: Brown, 1956a: 39; Taylor & Brown, 1985: 120; Taylor, 1987a: 15.
 * Unnecessary replacement name for darlingtoni Wheeler, W.M. 1934d: 160; hence junior synonym of darlingtoni: Brown, 1956a: 39; Bolton, 1995b: 120; McArthur, 2007a: 296.
 * christmasensis. Camponotus christmasensis McArthur, 2008: 115, figs. (w.) AUSTRALIA (South Australia, Western Australia).
 * Status as species: McArthur, 2010: 98; McArthur, 2014: 144.
 * Junior synonym of darlingtoni: Heterick, 2021: 17.

Taxonomic Notes
McArthur, Adams & Shattuck, 1997: 595: Brown (1956) synonymised Wheeler’s C. darlingtoni with Smith’s C. testaceipes (C. testaceipes is preoccupied and its replacement name is C. terebrans). This synonymy was based on Dr E. O. Wilson’s comparison of Wheeler’s types in MCZ with Smith’s type in BMNH, as Dr Brown did not compare the specimens himself. During this study, we have re-examined this material and find that C. darlingtoni is a valid species distinct from C. terebrans. In particular, C. darlingtoni lacks the cluster of elongate J-shaped setae on the mouthparts, a characteristic of the C. wiederkehri species-group, to which C. terebrans belongs. Thus, C. darlingtoni is removed from synonymy with C. terebrans and is here excluded from the C. wiederkehri species-group. To secure the identity of C. darlingtoni, a worker from Margaret River, Western Australia, which is housed in the MCZ collection, is here designated a lectotype.

Heterick (2021): Camponotus christmasensis is clearly conspecific with C. darlingtoni. The two ants are morphologically identical. Moreover, the West Australian data points on the distribution map for C. darlingtoni in McArthur (2007) exactly match those for C. christmasensis in the distribution map in McArthur (2010), in which publication C. darlingtoni is not mentioned at all! This suggests some confusion on the part of the author.

Donisthorpe, H. 1941 Entomologists Monthly Magazine 77:239. Synonymical Notes etc., on Formicidae (Hym.). Camponotus (Myrmophyma) darlingtoni Wheeler, 1934, J. Roy. Soc. West Aust., 20: 160, West Australia; Camponotus (Myrmocladoecus) sanctaefidei Della Torre subsp. darlingtoni Wheeler, 1934, Bull. Mus. comp. Zool. Harv., 77: 232, Trinidad. I am informed that the American publication appeared in print first, and therefore propose the name Camponotus (Myrmophyma) rottnesti nom. n. for the Australian insect.

Worker
Worker maxima Length 8-9 mm. Head subtrapezoidal, as broad as long or somewhat broader than long, high and convex above, flat below, with straight posterior and concave occipital border and convex sides. Eyes small, flat; ocelli present but minute. Mandibles stout, convex, with six subequal teeth. Clypeus subcarinate, its median section as long as broad, its anterior border straight in the middle, deeply sinuate on each side, not projecting beyond the anterior borders of the cheeks. Frontal area triangular, indistinct; frontal groove very distinct; frontal carinae approximately anteriorly, more separated and subparallel posteriorly. Antennae slender; scapes not extending beyond the posterior border of the head.Thorax short, its dorsal outline as far back as the epinotal angle evenly arcuate; promesonotal suture not impressed; metanotum present, but poorly defined posteriorly; epinotum laterally compressed, in profile with subequal base and declivity meeting at a distinct obtuse angle, the base straight and slightly sloping, the declivity more so and slightly concave. Petiolar scale rather high and narrow, thin, with convex anterior and flat surface, the superior border sharp and compressed, from behind semicircularly rounded, the sides feebly convex, converging ventrally. Gaster broadly elliptical. Legs moderately long, the fore femora increassated; middle and hind tibiae subterete, with a series of five or six short spines on their flexor surface. Finely and sharply shagreened, shining, gaster and posterior portion of head more so than the remainder of the body and the appendages; mandibles subopaque, coarsely punctate and like the clypeus and anterior portion of the head more coarsely shagreened or reticulate than the posterior portion. Cheeks, front and thoracic dorsum sparsely punctate; pleurae finely longitudinally striate; gaster delicately, transversely striolate, with sparser, piligerous punctates. Hairs white, erect, rather short, flexuous, very sparse; pubescence appressed, very short and sparse on the gaster and cheeks, longer on the pronotum, mesonotum and head, short and abundant on the antennae, longer and coarser on the legs, especially on the tibiae, where it is less appressed. Black; mandibles, clypeus, anterior border of cheeks, antennae, neck and posterior border of pronotum castaneous; posterior borders of gastric segments rather broadly, sordid whitish. legs, including the coxae, testaceous; tibiae slightly darker than the femora, tarsi red. Worker media Length 7-7.5 mm. Head much smaller than in the maxima, about one-sixth longer than broad, less narrowed anteriorly, with feebly and evenly rounded sides. Antennal scapes extending nearly one-third their length beyond the posterior border of the head. Pronotum semicircular anteriorly, flattened above, with more distinctly marginate sides; in profile with the dorsal outline broadly arcuate and made up of four subequal straight or nearly straight segments corresponding to the pronotum, mesonotum, base and declivity of epinotum, the anterior end of the mesonotum raised rather abruptly above the posterior end of the pronotum and both the base and the slightly shorter declivity of the epinotum distinctly concave so that the angle between them is pronounced. Petiolar scale narrower and thicker than in the maxima, with blunt superior border. In sculpture, pilosity and color very much like the maxima but the legs are more brownish testaceous and the basal halves of the coxae and femora are fuscous, the pale posterior borders of the gastric segments narrower. Worker minima Length 4-5.5 mm. Very similar to the media but the head longer, nearly one and one-third times as long as broad, with more subparallel sides, more convex eyes and the antennal scapes extending nearly half their length beyond the posterior border. Sides of pronotum sharply marginate; dorsal outline of thorax similar but the epinotum lower and more sloping and its base straight and nearly twice as long as the declivity. Petiolar scale much ticker and narrower, in profile almost subcuboidal, with straight anterior and posterior surfaces and horizontal, feebly rounded superior surface. Pilosity and coloration as in the media, but the head and thorax more opaque and more sharply shagreened; legs usually even more brownish.

Queen
(dealated). Length 11 mm. Head trapezoidal, very nearly broad as long, with straight posterior border and nearly straight, anteriorly converging sides. Eyes small but somewhat more convex than in the maxima. Antennal scapes reaching about one-fifth their length beyond the posterior border of the head. Thorax oval, about twice as long as long as broad, anteriorly distinctly broader than the head; mesonotum slightly broader than long, flattened posteriorly; epinotum short, its base convex, much shorter than the steep, concave declivity into which it passes without an angle. Petiolar scale like that of the maxima, but thicker and broader, compressed above, with its superior border somewhat produced upward in the middle. Gaster elongate-elliptical. Sculpture, pilosity and color as in the maxima, but the whole pronotum castaneous.

Type Material
Described from numerous specimens found nesting under logs and stones at Margaret River, Western Australia (type-locality) during October and November 1931, a single worker maxima and several minimae taken by Dr Darlington and myself at Longreach Bay (X.24'31) and Government House, Rottnest Island (X.31.'31) and a single small worker from King's Park, Perth.

References based on Global Ant Biodiversity Informatics

 * McArthur A. J., M. Adams, and S. O. Shattuck. 1998. A morphological and molecular review of Camponotus terebrans (Lowne) (Hymenoptera: Formicidae). Aust. J. Zool. 45: 579-598.
 * Wheeler W. M. 1934. Contributions to the fauna of Rottnest Island, Western Australia. No. IX. The ants. Journal of the Royal Society of Western Australia 20: 137-163.