Myopias tenuis

Colonies contain about 15 individuals and may have a single or multiple queens. They are known to prey upon Entomobryid collembola.

Identification
Willey and Brown (1983) - This is the smallest of the known Melanesian Myopias species, and also the most common and widespread. The typical form is small, has slightly convex sides of the head, scapes that just fail to reach (or just barely reach) the occipital border when held straight back, and a median clypeal lobe that is as long as, or slightly longer than, wide at its widest (near apex). The end of the lobe is convex or straight, and the free angles may be rectangular or rounded. Measurements for Papua New Guinea North Coast workers are: TL 2.8-3.7, HL 0.53-0.71, HW 0.45-0.60 (CI 81-91), ML 0.30-0.43 (MI 81-92), MLO 0.40-0.57, SL 0.42-0.58 (SI 87-95), EL 0.03-0.06, WL 0.95-1.25 mm. Workers of a colony series from Salawati Island, at the western end of New Guinea, fall within these dimensions and proportions. Workers from Bisianumu, in the hills above Port Moresby, fit the North Coast dimension range, while a sample from Karema, in the lowlands north of Moresby, tends slightly to exceed the North Coast samples in size.

Samples from the Cape York area of North Queensland average larger than any of the New Guinea series; a large worker from the Black Mt. Road, north of Kuranda, measures TL 4.1, HL 0.74, HW 0.67 (CI 91), ML 0.43 (MI 91), MLO 0.58, SL 0.59 (SI 88), EL 0.04, WL 1.34 mm. The Australian samples often have the laid-back scapes reaching the posterior border of the head, and the posterior border is more distinctly concave. In addition, the median clypeal lobe tends to be wider, often as wide as or wider than long, and the minute punctures, especially on the head, are a trifle coarser and more distinct. Several of these series have sordid yellowish individuals, undoubtedly partly callow, that correspond to var. fulvescens.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: New Guinea.

Biology
Willey and Brown (1983) - PAPUA NEW GUINEA: Karema, Brown R., rotten log, lowland rain forest, leg. Wilson, No. 552. Bisianumu, near Sogeri, about 500 m, hill rain forest, Wilson Nos. 637, 637 A, litter and rotten wood, strays. In the vicinity of Lae (Didiman Creek, Bubia and lower Busu R.), several nests and litter strays, Wilson Nos. 688, 689A, 690, 716, 939, 962, 978, 1037, 1045, 1058, all in lowland rainforest. No. 689 was a small colony in a Zoraptera-stage log, with about ten workers and two queens. No. 716 was a worker carrying an entomobryid collembolan about its own length lengthwise beneath its body, army ant fashion. No. 1037 was a nest in a cavity in the under surface of a hard, barkless log in leaf litter. No. 1045, a nest in a soft Passalus-stage log, had peripheral galleries packed with unidentified arthropodan cuticular fragments. Nadzab, dry evergreen forest, Wilson No. 1100. Wau north, on Bulolo road, 650 m, leg. S. Peck, B-278. IRIAN JAYA: near Phillips Petroleum Base Camp, SE Salawati l. (just off western extremity of Vogelkop), swamp forest near sea level, leg. Brown No. 81-189, nest in rotten wood, with at least 15 workers, a dealate queen, a male, about a dozen pupae in tan cocoons, and a few half-grown larvae. AUSTRALIA, N. QUEENSLAND: Black Mt. road N. of Kuranda, 300-600 m, leg. P. F. Darlington, in rain forest, small colony with at least two dealate queens. Mt. Cudmore Range, II mi. N. of Ingham, about 210 m, six workers from rotten log in small roadside patch of disturbed rain forest, leg. Taylor, Acc. No. 1706. Mulgrave Forestry Road, 17°18'S, 145°48'E, leg. Ward No. 4366, from rotting epiphyte fern on rain forest floor.

From the SOLOMON ISLANDS we have three scanty samples of forms sent from ANIC that could belong to M. tenuis. or to sibling species:

(1) A large form, extending some of the tendencies seen in Australian series; HW 0.80, EL 0.09 mm; scapes reaching posterior border of head. Propodeal dorsal profile a little more convex than usual in M. tenuis. Color castaneous. Two workers from Guadalcanall.: Mt. Austen, Feb. 1966, leg. P.M. Greenslade, No. 21095.

(2) A small worker, also from Mt. Austen, Guadalcanal, 14/5/1963, leg. P.M. Greenslade, No. 6076; HW 0.55, EL 0.03 mm; scapes very short, failing to reach posterior border of head by at least the apical scape width; posterior border of head weakly concave. Color yellowish brown. Sides of head straighter and more parallel-sided than in the other Mt. Austen sample.

(3) A worker from San Cristovall., Humi R. est., N.E. Wainoni, leg. Royal Society Expedition, 1966-1, HW 0.60, EL 0.05 mm; sides of head almost perfectly straight and parallel, posterior border feebly convex; scape fails to reach posterior border of head by about half of apical scape width; mandibles unusually short (ML 0.37, MLO 0.47 mm) and broad; basal angle forming a distinct convexity. Color deep brownish red.

I suspect that the Solomons will eventually yield much more variation in the tenuis complex; the available material is simply inadequate as a basis for understanding the complex in this archipelago.

Nomenclature

 *  tenuis. Trapeziopelta tenuis Emery, 1900c: 313, pl. 8, fig. 3 (q.) NEW GUINEA. Emery, 1901h: 155 (w.). Combination in Myopias: Willey & Brown, 1983: 270. Senior synonym of fulvescens: Willey & Brown, 1983: 270.
 * fulvescens. Trapeziopelta tenuis var. fulvescens Emery, 1901h: 155 (w.q.) NEW GUINEA. Junior synonym of tenuis: Willey & Brown, 1983: 270.

Type Material
Willey and Brown (1983) - dealate queen. Type loc.: Beliao Island, near Berlinhafen (now Aitape), Papua New Guinea.