Melophorus longipes Heterick, Castalanelli & Shattuck

Heterick, Brian E., Castalanelli, Mark & Shattuck, Steve O., 2017, Revision of the ant genus Melophorus (Hymenoptera, Formicidae), ZooKeys 700, pp. 1-420 : 240-243

Melophorus longipes Heterick, Castalanelli & Shattuck sp. n.

Types.

Holotype minor worker (bottom ant) From 10 km from Mt Ive Homestead, South Australia, 22 October 1980, P.J. M. Greenslade, B Se Gawler Ranges, South Australia, 16 (ANIC). Paratypes: 2 major workers on same pin and with same details as holotype (ANIC); 3 major workers from 85 km W Mabel Creek, South Australia, 9 October 1980, P.J. M. Greenslade, Sa EAD; (Top major worker photographed) [ANIC32-900193] (ANIC); major and 2 minor workers from 14 km S by W of Beltana, 30°56'S, 138°23'E South Australia, 14 September 1972, J.E. Feehan, ANIC Ants Vial 16.99 (MCZ); major and minor worker from Poochera 32°43'S, 134°50'E, Australia, 10-13.xi.1981, R.W. Taylor and R.J. Bartel, 'Freightline site’ grassy areas not under trees, ANIC Ants Vial 1.167 (BMNH); media and minor worker from Vokes Hill, Victoria Desert, South Australia, 2 October 1976, P.J. M. Greenslade, (6) a, 8 (SAM); 2 majors and a minor worker from 19 miles SE by S of Karonie, 31°12'S, 122°42'E, Western Australia, 9 Nov. 1969, Key’s field notes. Trip 163. Stop 19392.9 (WAM); major and minor worker from Woolgangie, Western Australia, 18 September 1988, B. Heterick, soil, native veg., rural environ., 433, 8MelBH7C (WAM).

Other material examined.

Northern Territory: about 50 km E Finke (Feehan, J.E.). South Australia: 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. ), 10 km E Mt Ive Homestead, Gawler Ranges (Greenslade, P.J. M. [ANIC32-900192]), 1 mi S Victory Downs Homestead (McInnes & Dowse), 20 mi W Mt Whinham (McInnes, R. & Dowse, J.), 25 mi NE Maralinga (McInnes & Dowse), 29 km ENE Yantanabie (Taylor, R.W., Bartell, R.J. & Lowery, B.B.), 34 mi NW Woomera (Greaves, T.), 3 km NE homestead, Koonamore (Greenslade, P.J. M. ), 3 mi S Mt Morris, Musgrave Range (McInnes & Dowse), 5 mi NW Coffin Hill (McInnes & Dowse), Blyth, 4 mi W Clare (Lowery, B.B.), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Cambrai (Greenslade, P.J. M. ), Eyre Highway, 38 km W Kimba (Heterick, B.E.), Eyre Hwy, 9.7 km NE Cootra (Heterick, B.E. [M327]), Gawler Ranges (Greenslade, P.J. M. ), Gawler Ranges (Greenslade, P.J. M. ), Poochera (Taylor, R.W. & Bartell, R.J.), 50 km E Vokes Hill, Victoria Desert (Greenslade, P.J. M. ). Western Australia: 1 km W Canna (Heterick, B.E. [M318]), 1.5 km S Koolyanobbing (Heterick, B.E. [M60]), 16 km S Mt Magnet (Heterick, B.E. [M291/M292]), 19 km N Hines Hill (Heterick, B.E. [M05/M22/M33/M34]), 19 mi SEbyS Karonie (Taylor, R.W.), 20 mi SW Mundiwindi (McInnes & Dowse), 23 mi SWbyS Coolgardie (Taylor, R.W.), 26 mi NWbyW Norseman (Taylor, R.W.), 6 mi W Karonie (Greaves, T.), 8 km N Bullfinch (Heterick, B.E. [M124]), 9 mi W Zanthus (Taylor, R.W.), Beebyn Stn. (Heterick, B.E. [JDM32-001783]), Coomallo Downs (Heterick, B.E. [M03/M42]), Dedari, 320 mi E Perth (Douglas, A.), Ethel Creek (Varris, P.A. [JDM32-001793]), Junana Rock, 9 km NW Mt. Ragged (Taylor, R.W.), Kadji Lake Rd. (Heterick, B.E. [JDM32-001795]), Kalgoolie (Greaves, T.), Mardathuna Rd turnoff (Heterick, B.E. [M23/M56]), Mulga, NE Goldfields (Pringle, H.J.R. [ANIC32-029564]), Port Hedland (Weatherill, L.).

Diagnosis.

Melophorus longipes can be placed in the M. biroi species-group on the basis of characters of the clypeus, propodeum, mandible and palps. The species is also placed in the M. fieldi species-complex because of the appearance of the anteriorly placed clypeal psammophore, the compact propodeum, the presence of more than one preapical spine on the metatibia, at least in the major worker, the long, even spindly legs and the unmodified mandible in the major worker. Melophorus longipes can be confused with several very similar and highly derived Melophorus that are also common and widespread, and specimens have to be checked carefully using the following characters before they can be distinguished from M. eumorphus , M. turneri and M. vitreus : Melophorus longipes can be distinguished from M. eumorphus by its larger size (minor worker HW 0.57 mm ≥; major worker HW> 1.50 mm); and less strongly sculptured mesopleuron. In turn, the Melophorus longipes minor workers lack the protuberant clypeus seen in M. vitreus minors, the clypeus being only weakly protuberant and usually with a distinct dimple at its anterior midpoint, are less gracile, have a squamiform petiolar node and do not exhibit the " pillipes " condition (which is general in M. vitreus ). It is with many populations of Melophorus turneri that Melophorus longipes can be most easily confused. However, in M. longipes the metafemur of the minor worker is longer and attenuated towards its junction with the tibia (metafemur ≥ 0.90 × length of mesosoma) compared with the shorter, stouter metafemur in the M. turneri minor (metafemur ≤ 0.75 × length of mesosoma). In profile, the dorsum of the minor worker propodeum is smoothly curved on to its declivitous face in M. longipes whereas there is often a distinct angle in the case of M. turneri . Major workers are more difficult to differentiate. However, the major worker mesonotum in M. longipes is flat to weakly convex versus weakly to moderately convex in M. turneri major workers, the M. longipes major worker metafemur is increasingly depigmented towards its articulation with the tibia, and the tibia is depigmented yellowish-white. The appearance of the major worker metafemur in M. turneri workers seen is always uniform and similar in colour pattern to the tibia, both parts being ochraceous to yellowish.

Minor worker description.

Head. Head square; posterior margin of head planar or weakly convex; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only; Eye moderate (eye length 0.20-0.49 length of side of head capsule); in full-face view, eyes set at about midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly convex with anteromedial clypeal dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and tooth numbers two and four; masticatory margin of mandibles vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen and superficial microreticulation (more pronounced on mesopleuron); anterior mesosoma broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum matt or with a weak sheen and microreticulate-striolate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae few in number, may be absent; appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform to narrowly conical, vertex bluntly rounded; in full-face view, petiolar node tapered with blunt vertex; node shining and smooth throughout. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced erect and semi-erect setae interspersed with regularly placed appressed setae. General characters. Body tan with a brown gaster and the legs a light tan, becoming pale yellow distally.

Major worker description.

Head. Head square; posterior margin of head planar or weakly convex; frons shining with superficial shagreenation or microreticulation only; pilosity of frons a mixture of a few well-spaced, erect setae interspersed with appressed setae only; Eye moderate (eye length 0.20-0.49 length of side of head capsule); in full-face view, eyes set above midpoint of head capsule; in profile, eye set anteriad of midline of head capsule; eyes elliptical or slightly reniform. In full-face view, frontal carinae straight, divergent posteriad; frontal lobes straight in front of antennal insertion. Anteromedial clypeal margin broadly convex with anteromedial clypeal dimple; clypeal psammophore set at or above midpoint of clypeus; palp formula 6,4. Five mandibular teeth in major worker; mandibles triangular, weakly incurved; third mandibular tooth distinctly shorter than apical tooth and tooth numbers two and four; masticatory mar gin of mandibles vertical or weakly oblique. Mesosoma. Integument of pronotum, mesonotum and mesopleuron with weak to moderate sheen and superficial microreticulation (more pronounced on mesopleuron); anterior mesosoma broadly convex; appearance of erect pronotal setae short, (i.e., longest erect setae shorter than length of eye) and unmodified; in profile, metanotal groove shallow, broadly V or U-shaped; propodeum matt or with a weak sheen and microreticulate-striolate; propodeum smoothly rounded or with indistinct angle; propodeal dorsum and declivity confluent; erect propodeal setae present and abundant (greater than 12); appressed propodeal setae short, separated by more than own length and inconspicuous; propodeal spiracle situated on or beside declivitous face of propodeum, and shorter (length <0.50 × height of propodeum). Petiole. In profile, petiolar node squamiform; in full-face view, node uniformly rounded or tapered with blunt vertex; node shining with vestigial sculpture. Gaster. Gaster shining, shagreenate ('LP record’ appearance); pilosity of first gastral tergite consisting of well-spaced erect and semi-erect setae interspersed with regularly placed appressed setae). General characters. Body tan with a brown gaster and the legs an increasingly pale yellowish, becoming depigmented distally.

Measurements.

Worker (n = 10): CI 105-124; EI 18-33; EL 021-0.30; HL 0.61- 1.38; HW 0.64-1.70; ML 0.87-1.70; MTL 0.62-1.10; PpH 0.11-0.17; PpL 0.36-0.70; SI 69-118; SL 0.75-1.17.

Comments.

This species shares with M. turneri and M. vitreus a generally glabrous mesosoma with well-spaced, tiny appressed setae on the first gastral tergite. The ant can readily be separated from M. vitreus by its smaller eye and more squamiform node in the minor worker. In common with many Melophorus , major workers of this species are nondescript and easily mistaken for the majors of M. turneri , the easiest way to distinguish them being the light coloured, depigmented tibia and distal femora when compared with M. turneri major workers (which have tawny yellow or orange limbs). Distinguishing minor and media workers of M. longipes from M. turneri requires examination of the metatibia, which is measurably longer or at least narrower in individuals of the same size within the two species (total range 0.61-1.10 mm in M. longipes compared with 0.61-0.98 mm in M. turneri ). In other respects, the two ants are virtually identical. Melophorus longipes records are restricted to SA and WA with just one NT record (50 km E Finke River). Despite its close physical similarity to M. turneri , the sister species of M. longipes is unclear, based on various gene trees. Populations of this species are closely related, and cluster tightly together on all individual gene trees. Also, unlike a number of other members of the M. fieldi complex, the ' pillipes ' condition has not been seen in M. longipes .

Although both M. longipes and M. turneri are often sympatric, most records of M. longipes have come from inland locations well away from the coast. All vegetation records mention mallee, and this is therefore assumed to be the favoured habitat for this species. There are also several records of dunes and one of a salt lake and sand ridge. No data on the behaviour of the ant are available, but it is probably a generalist, given its distribution and morphology.

Etymology.

Latin longus ( ‘long’) plus pes ( ‘foot’); adjective in the nominative singular.