Eurhopalothrix procera

Longino (2013): A single alate queen from La Selva Biological Station in Costa Rica closely matches E. procera, based on literature descriptions and images on AntWeb. The specimen was obtained in a canopy fogging sample in October, 1994, as part of a large-scale arthropod survey project. In spite of intensive sampling for ants at this site (Longino et al., 2002), no other specimens were collected, and this single queen remains the only known specimen of E. procera from the New World. This is remarkable, because E. procera is a polytypic species found in New Guinea and multiple Pacific islands west of New Guinea (Brown and Kempf, 1960; Taylor, 1968, 1980; AntWeb, 2013), and related species also occur in this region (Taylor, 1968, 1970, 1980). Taylor (1980) describes E. procera as "Widespread in rain forest and marginal habitats; East Indies, Philippines, Melanesia, Polynesia east to the Samoan Islands, and Cape York Peninsula ..." Its occurrence on multiple oceanic islands and in marginal habitats suggests a high dispersal ability and raises the possibility that it is an adventive species in Costa Rica. Alternatively, it may be a relict lineage with a rare Neotropical representative.

Identification
Eurhopalothrix procera has the double tooth row found in Eurhopalothrix gravis and relatives. The double tooth row is visible on the La Selva queen and on the AntWeb image of a queen from the Philippines (Holotype of E. procera subdentatus [Donisthorpe, 1942], a junior synonym of E. procera). It is unknown whether other species in the procera group also have the double tooth row. Cursory examination of the three Old World species Eurhopalothrix australis, Eurhopalothrix dubia, and Eurhopalothrix omnivaga showed that these species lack the double tooth row.

The labrum of the La Selva queen is elongate, triangular, with two small lobes at the apex. The labrum is visible on the image of the E. procera subdentatus holotype, and appears similar. The La Selva queen is smaller and with narrower head than other known E. procera queens. Brown and Kempf (1960) report worker HW 0.98–1.35 and CI 106–111, with queens being the same as or slightly larger than workers. The La Selva queen has HW 0.91 and CI 95.

Key to New World Eurhopalothrix

Key to Australian Eurhopalothrix Species

Key to Old World Basicerotini

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: Borneo, Indonesia, New Guinea, Palau, Philippines, Samoa, Solomon Islands. Neotropical Region: Costa Rica.

Nomenclature

 *  procera. Rhopalothrix procera Emery, 1897c: 572, pl. 14, fig. 18 (w.q.) NEW GUINEA. Combination in Eurhopalothrix: Brown & Kempf, 1960: 225. Senior synonym of angulinodis, ballionii, borneensis, kokodensis, malua, manni, samoana, subdentatus and material of the unavailable name melanotica referred here: Brown & Kempf, 1960: 225.
 * ballionii. Rhopalothrix procera var. ballionii Forel, 1904d: 175 (w.) INDONESIA (Morotai I.). Junior synonym of procera: Brown & Kempf, 1960: 225.
 * borneensis. Rhopalothrix borneensis Wheeler, W.M. 1919e: 96 (q.) BORNEO. Junior synonym of procera: Brown & Kempf, 1960: 225.
 * malua. Rhopalothrix procera subsp. malua Mann, 1919: 358, figs. 36-38 (w.q.m.) SOLOMON IS. Junior synonym of procera: Brown & Kempf, 1960: 225.
 * manni. Rhopalothrix manni Menozzi, 1923b: 210, fig. 2 (w.) PHILIPPINES. Junior synonym of procera: Brown & Kempf, 1960: 225.
 * angulinodis. Rhopalothrix angulinodis Stitz, 1925: 122 (w.) PHILIPPINES (Palawan I.). Junior synonym of procera: Brown & Kempf, 1960: 225.
 * samoana. Rhopalothrix procera st. samoana Santschi, 1928a: 51, fig. 5 (w.m.) SAMOA. Junior synonym of procera: Brown & Kempf, 1960: 225.
 * kokodensis. Rhopalothrix (Rhopalothrix) kokodensis Donisthorpe, 1936e: 524 (q.m.) NEW GUINEA. Junior synonym of procera: Brown & Kempf, 1960: 225.
 * subdentatus. Rhopalothrix (Rhopalothrix) subdentatus Donisthorpe, 1942b: 67 (q.) PHILIPPINES. Junior synonym of procera: Brown & Kempf, 1960: 225.

Worker
Brown & Kempf (1960) - TL 3.9-5.3, HL 0.92-1.27, HW 0.98-1.35 (CI 106-111), scape L 0.51-0.78, greatest diameter of eye 0.07-0.10, WL 1.07-1.43 mm; based on 44 workers from all parts of the range.

Except for Eurhopalothrix emeryi, this is the largest species of the genus. The form of head and alitrunk are shown in the figrue. The occiput, alitrunk, both nodes and gastric dorsum with a more or less distinct, but shallow and broad, median longitudinal sulcus, in which pilosity is weak or absent.

Petiolar node cuboidal, about as broad as long when seen from above. Postpetiole large, a little more than twice as wide as petiolar node and about 3/4 as wide as gaster, but only about 1/3 broader than long; posteriorly with a strong median emargination, on each side of which is a low, blunt eminence or lobe.

The pilosity varies considerably, but the pair of erect clavate or spatulate hairs on the paired eminences of the vertex is constant, as is the pair of clavate hairs on the paired pronotal (humeral) eminences, and the circlets of small clavate hairs on the apical segments of the gaster. Erect clavate hairs on the gaster 0-10; when present arranged in two longitudinal rows; the- more posterior hairs are the most persistent ones in the course of evolutionary reduction of the pilosity. Subappressed spatulate ground pilosity usually best developed on clypeus, scapes, legs and humeri, obsolescent to well developed and abundant elsewhere, according to geographic locality. Sculpture also varying widely geographically, from coarsely and densely rugulose punctate to lightly shagreened-punctate and shining. Color ferruginous to dark reddish-brown.

Queen
Brown & Kempf (1960) - With the usual caste differences; head measurements usually the same as, or slightly greater than, those of the large workers from the same nest series; largest females seen (from the Philippines) measure HW 1.30 and 1.33 mm. The New Guinea females may be a little larger proportionate to their workers, according to the figures of previous authors. Forewing L (3 Philippines specimens) 4.6-5.0 mm (1 specimen from Santa Cruz Islands) 4.2 mm. For wing venation, see under male, below). Mesonotum with a few erect truncate hairs.

Male
Brown & Kempf (1960) - TL 3.5-4.2, HL 0.68-0.87, HW 0.68-0.78, WL 1.08-1.31 mm. Greatest diameter of compound eye 0.25-0.27, forewing L 3.3-4.3 mm.

A male of the Solomons Islands populations ("subsp. malua") is described by Mann (loc. cit.), and the figure with Mann's description will serve for this caste if the considerable variation of males in this species is borne in mind, and if a few corrections are made. Actually, the scape and first funicular segment are stouter than as shown, the ocelli are larger, and the petiolar node is a little higher and more definitely cuboidal. Mann describes the anteroventral process of the petiolar peduncle as " long and slender", although it is not shown in his figure. The process is as Mann says it is in two of his Solomons samples (San Cristoval and Isabel), but is vestigial in a male from Kokoda, Papua, and is absent in one from Babelthuap in the Palau Group.

The mandibles are triangular, barely opposable, with rounded basal angle and nearly or quite unarmed masticatory border terminating in an acute apical angle or tooth. Forewing of the type or Creightonidris, but more reduced ; M+Rs and the free apical abscissae of Rs, M and Cu absent or reduced to faint traces. The female venation is similar, except that the Rs, though very weak, may reach the wing margin.

On the head there are 2 or 3 pairs of slender erect truncate hairs on the ocellar eminence and other slender hairs elsewhere, especially on the mandibles and gula. Several long erect truncate hairs on each occipital angle in the Solomons specimens, 2-3 on each angle in the Kokoda, Papua, specimen, and none on the angles in the Babelthuap specimen. The alitruncal dorsum has sparse, long, curved, tapered hairs, and the gastric apex has slender clavate or truncate hairs. The largest specimen seen (Kokoda, Papua) has HL 0.87 mm, and the sculpture is coarse. The Babelthuap specimen is smallest (HL 0.68 mm), but has a relatively broad head (HW 0.68 mm), and the postpetiole and gastric dorsum are shining. Color deep reddish-brown to blackish-brown, the head darkest.