Myrmecorhynchus carteri

Myrmecorhynchus carteri occurs from north-coastal New South Wales south to Tasmania (it is the only species known from Tasmania). It is found in mallee, thick scrub, dry to wet sclerophyll (including Eucalyptus pauciflora, E. perriniana and E. stellulata forests), coastal scrub (wet scrub; hillside, black soil; at water’s edge) and rainforest. Nests are in dead branches or twigs above the ground (including Acacia sophorae, Eucalyptus perriniana and E. stellulata) or occasionally on the ground, or less commonly in soil under rocks. One nest was found in a dead, rotten branch with a colony of Myrmecorhynchus emeryi; however the relationship between these ants, if any, is unknown. Foragers are commonly found on tree trunks and are known to visit Eucryphia lucida flowers and wander into malaise traps. The larvae were described by Wheeler & Wheeler (1970).

Identification
Mesosomal dorsum with at most a few scattered erect hairs, legs with appressed pubescence but lacking erect hairs; at most a narrow band of yellow on anterolateral clypeal margin; mandibles bicoloured, yellow basally and dark apically; propodeum higher and more rounded and metapleural groove more strongly angled when compared to Myrmecorhynchus nitidus.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  carteri. Myrmecorhynchus carteri Clark, 1934b: 43, pl. 3, figs. 11, 12 (s.w.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1970: 648 (l.).

Type Material


Note: A specimen in the (CASENT0903253) from Woori Yallock, Victoria, and labeled as a syntype ("cotype") is not a true type as this locality is not mentioned in the original description of this taxon.

Taxonomic Notes
Morphologically this species is similar to M. nitidus, differing in colour pattern and the shape of the metanotal groove and propodeum. While colour pattern shows considerable variation in Myrmecorhynchus emeryi, this does not seem to be the case here. All known specimens show either the M. carteri or M. nitidus patterns with no intermediate individuals being found. Thus colour suggests that these two taxa are distinct. The shape of the metanotal groove and propodeum also support this conclusion. All known specimens of M. carteri have the propodeum higher and more rounded dorsally compared to M. nitidus workers, resulting in the metanotal groove being more distinct and angular. As with colour, all specimens show one or the other pattern with intermediate forms unknown. Combined, these characters suggest that two separate taxa are involved rather than a single variable species.

Worker
Major. Length, 4.3-4.7 mm.

Black; mandibles and antennae ochraceous; apical half of mandibles, anterior edge of pronotum, knees, tibia and tarsi ferruginous; node and gaster chocolate brown.

Shining. Mandibles very finely striate longitudinally. Head and thorax finely reticulate, having a circular direction, on pronotum and mesonotum. Node and gaster smooth.

Hair yellow, long, erect, very sparse throughout. Pubescence very fine and adpressed, abundant on antennae, sparse on legs, hardly apparent on body.

Head a fraction longer than broad, much broader behind than in front, sides and occipital border convex, angles broadly rounded. Mandibles triangular, furnished with eight strong, sharp teeth. Clypeus produced, the anterior border straight in middle. Frontal area transversely triangular. Frontal carinae one-fourth broader than long. Scapes extending beyond occipital border by one-fifth their length; first segment of funiculus as long as the three following together, second to ninth as broad as long, tenth slightly longer than broad, apical as long as the two preceding together. Eyes large, convex, placed about three-quarters of their length from anterior angle. Ocelli large. Thorax one and three-quarters times longer than broad. Pronotum one and two-thirds times broader than long, strongly convex, suture strongly impressed. Mesonotum almost circular, slightly broader than long. Constriction between meso- and epinotum wide and deep, the spiracles placed on top at sides of the depression. Epinotum slightly broader than long, strongly convex, posterior border almost straight. In profile pronotum and mesonotum convex, suture hardly indicated. Spiracles prominent in meso-epinotal depression. Epinotum strongly convex, rounded into declivity, the latter longer than dorsum. Node oval, fully twice as broad as long, convex laterally; in profile almost twice as high as long, anterior and posterior faces feebly convex, almost parallel, rounded into dorsum; a short blunt tooth in front below. Gaster one and two-third times longer than broad. Legs slender.

Minor. Length, 3-3.3 mm.

Colour, sculpture and pilosity as in major from which it differs as follows:

Head one-seventh longer than broad, sides and occipital border strongly convex. Mandibles slightly longer and narrower. Scapes extending beyond occipital border by one-fourth their length. Dorsum of thorax similar, but in profile the epinotum higher and more convex. The node a little more slender, more pointed above.