Dolichoderus ypsilon

This species is restricted to south-west Western Australia. The male was described by Forel (1907).

Identification
A member of the Dolichoderus scabridus species group.

Pronotum rounded, lacking spines; propodeum with elongate spines directed upward at angle of 45° or less to horizontal plane, the angle between them at least 90°; dorsum of petiolar node angular, base of propodeal spines forming a "V" with a narrowly rounded angle connecting their bases; legs entirely light red or orange.

This species can be distinguished from Dolichoderus inferus and Dolichoderus scabridus by the dorsum of its petiolar node being angular rather than broad, and the base of the propodeal spines forming a narrowly angled "V" rather than a broad "U" when viewed from the front. Additionally, D. ypsilon can be distinguished from Dolichoderus rufotibialis and Dolichoderus niger by the distinctive colour of its entirely red or orange legs.

Identification Keys including this Taxon

 * Key to Australian Dolichoderus Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  ypsilon. Dolichoderus scabridus r. ypsilon Forel, 1902h: 461 (w.) AUSTRALIA. Forel, 1907h: 284 (m.). Combination in D. (Hypoclinea): Emery, 1913a: 13; in D. (Diceratoclinea): Wheeler, W.M. 1935c: 69. Subspecies of scabridus: Forel, 1915b: 76. Raised to species: Forel, 1907h: 284; Clark, 1930b: 258.

Worker
Clark (1930) - Black. Legs and spines red, mandibles and coxae darker red.

Shining. Head punctate, the punctures shallow, the spaces between them finely reticulate. Pronotum and mesonotum with somewhat similar punctures, but more scattered. Top of the node coarsely rugose. Gaster microscopically punctate.

Hair yellow, long and erect, abundant throughout, shorter and suberect on the antennae and legs. Pubescence very fine and adpressed on the antennae, coxae and legs, longer and more abundant on the gaster, where it forms a yellowish clothing, not hiding the sculpture.

Head slightly longer than broad, the occipital border and sides convex. Frontal carinae short and parallel, as long as their distance apart. Clypeus with a distinct median groove from the base to the anterior border, the latter convex with a deep excision in the middle. Scapes extending beyond the occipital border by one-third of their length; first segment of the funiculus one-fourth longer than the second, and twice as long as the third. Eyes globular, placed at the middle of the sides. The masticatory border of the mandibles furnished with fine denticles; terminal border with strong sharp teeth. Thorax one and two-thirds times longer than broad. Pronotum one-third broader than long, convex above. Mesonotum slightly broader than long, feebly convex above. Epinotum short, as long as broad, furnished with two long sharp spines, directed upward, outward and backward, meeting at their base; in profile the dorsum short, almost fully occupied by the base of the spines, they are nearly straight and rise at an angle of sixty degrees, the declivity abrupt, longer than the basal face. Node fully twice as broad as long, concave in front, convex behind, the dorsum straight; in profile parallel, to near the top, the dorsum and posterior face united in a convexity. Gaster longer than broad, concave in front below. Legs long and slender.

Shattuck and Marsden (2013) - Generally similar but with legs more yellow (slightly less red) in some individuals. Also, a few specimens have the sculpturing on the mesosomal dorsum reduced medially, this region being nearly smooth.

Measurements (n=5). CI 92–96; EI 20–25; EL 0.21–0.29; HL 1.14–1.29; HW 1.05–1.22; ML 1.60–1.81; MTL 0.95–1.15; PronI 69.93–74.15; PronW 0.76–0.90; SI 109–118; SL 1.22–1.36.

Male
Clark (1930) - Yellowish red, gaster darker, apical segments brown.

Opaque. Scutellum, epinotum, node and gaster more or less shining. Head and mesonotum very finely reticulate and with some very shallow scattered punctures.

Hair yellow, erect, abundant throughout. Pubescence whitish, hardly apparent, except on the antennae and legs.

Head almost as broad as long, strongly convex behind and on the sides. Frontal carinae short and erect. Clypeus convex above, produced in front. Eyes very large and convex, occupying a little more than half the sides of the head. Ocelli very large and globular. Scapes fully three times longer than the first segment of the funiculus, and almost twice as long as the second. Mandibles furnished with numerous small sharp teeth. Mesonotum overhanging and hiding the pronotum in front; mayrian furrows not apparent, parapsidal furrows sharply impressed. Scutellum almost circular, broader than long. Epinotum short and broad; in profile convex longitudinally, the declivity abrupt, as long as the dorsum. Node one and one-third times broader than long. Gaster much longer than broad. Cerci long and stout. Outer and middle processes of the genitalia slender, strongly curved downward at the points. Wings hyaline, with a slight smoky tinge. Legs long and slender.

References based on Global Ant Biodiversity Informatics

 * Clark J. 1930. The Australian ants of the genus Dolichoderus (Formicidae). Sugenus Hypoclinea Mayr. Australian Zoologist 6: 252-268.
 * Forel A. 1902. Fourmis nouvelles d'Australie. Rev. Suisse Zool. 10: 405-548.
 * Forel A. 1915. Results of Dr. E. Mjöbergs Swedish Scientific Expeditions to Australia 1910-13. 2. Ameisen. Ark. Zool. 9(16): 1-119
 * Shattuck S. O. 1994. Taxonomic catalog of the ant subfamilies Aneuretinae and Dolichoderinae (Hymenoptera: Formicidae). University of California Publications in Entomology 112: i-xix, 1-241.
 * Shattuck S. O., and S. Marsden. 2013. Australian species of the ant genus Dolichoderus (Hymenoptera: Formicidae). Zootaxa 3716(2): 101-143.