Bothriomyrmex paradoxus Dubovikov and Longino, 2004

Dubovikov, D. A. & Longino, J. T., 2004, A new species of the genus Bothriomyrmex Emery, 1869 (Hymenoptera: Formicidae: Dolichoderinae) from Costa Rica., Zootaxa 776, pp. 1-10 : 3-8

Bothriomyrmex paradoxus Dubovikov and Longino , sp. nov.

Figures 1-5

Holotype queen: Costa Rica, Prov. Guanacaste, Guanacaste Conservation Area, Estacion Cacao , 10°55'N 85°30'W, 1100m , 22 Feb 2003, tropical montane moist forest , sweep sample (J. S. Noyes), specimen barcode JTLC000004280 [ INBio].

Paratypes: 3 queens and 3 males, same data as holotype [ ZIN]; queen and 2 males, same data as holotype [ MCZC]; 2 queens, same data as holotype [ LACM, INBio]; 5 workers, Costa Rica, Prov. Heredia, 11 km SE La Virgen , 10º20´N 84º04´W, 500m , 19 Apr 2003, coll. R. Vargas C., 05-RVC-007 [ ZIN]; 4 workers, same data [ MHNG]; 5 workers, same data but 16 Feb 2003, coll. J. Longino ( JTL4938 ) [same colony] [ CAS, INBio, LACM, UCDC, USNM] .

Holotype measurements: HL 0.600; HW 0.526; SL 0.424; TL 0.697; TH 0.448; PH 0.227; TI 0.643; CI 0.876; SI 0.706.

Paratype measurements (average for 3 queens): HL 0.600; HW 0.543; SL 0.436; TL 0.700; TH 0.450; PH 0.257; TI 0.643; CI 0.905; SI 0.726.

Paratype measurements (average for 5 workers): HL 0.586; HW 0.520; SL 0.434; PH 0.239; CI 0.888; SI 0.742.

Paratype measurements (average for 3 males): HL 0.457; HW 0.479; SL 0.257; OL 0.171; PH 0.179; OI 0.667; CI 1.047; SI 0.563.

Etymology: named for the paradoxical occurrence of this species in the New World, when the genus was previously considered strictly Old World.

Diagnosis: Queen with short suberect setae on mesosoma and gaster; queen mesosoma short and high (TI> 0.64); worker mesosoma with impressed metanotal groove.

Description (queen): Palp formula 4:3; head oblong, with rounded posterolateral vertex margins; suberect hairs of variable length on genae (Fig. 2a); clypeus broad, width in center 0.2 mm (average for 4 queens), with curved setae on anterior margin; mandible long, with outer and basal margin subparallel, masticatory margin with three teeth and 4- 5 denticles; mesosoma short and high, with erect setae on dorsum and posterior face of propodeum; wings with closed cubital and radial cells (Fig. 1c); petiole with strongly developed ventral lobe, dorsal scale inclined anteriorly; gaster with many long setae on posterolateral margins of tergites; body dark brown; entire body with short suberect pubescence, distance between hairs subequal to length.

Description (worker): Palp formula 4:3; medial hypostoma absent (Fig. 3d); head with two long setae on the frons, two on the posterior clypeal margin, and many curved setae on the anterior clypeal margin; metanotal groove impressed (Fig. 3a); dorsal face of propodeum rounded, much shorter than posterior face; petiolar node scale-like, tall, inclined anteriorly; ventral margin of petiole with prominent lobe (Fig. 3c); gaster with long setae on posterior margins of tergites; pubescence short and dense over entire body; body dark brown, with lighter antennae and legs.

Description (male): Scape long, projecting beyond outer eye margin (in face view) by about half of its length; propodeum rounded, without differentiated dorsal and posterior faces; petiole with short anterior peduncle; petiolar node low, thin, vertical; ventral margin of petiole with small anterior denticle and strongly developed medial lobe (Fig. 4); sagitta thin, with apex weakly folded down.

Description (larva): Body with two protuberances on the prothorax, located ventrolaterally; hairs short; eight pairs of spiracles (Fig. 5).

Biology: Bothriomyrmex paradoxus is known from two different collections from widely separated localities in Costa Rica (Fig. 1). One collection was made in February 2003, during the Project ALAS expeditions to the 500m site on the Volcan Barva transect. The expeditions were based at the "El Ceibo" guard station, on the west bank of the Rio Peje. The station building itself is in pasture abutting mature rainforest. A few meters inside the forest a large tree had fallen sometime during the months prior to the expeditions. A few of the tree's leaves were still green; most were brown but still attached to branches. There were still extensive epiphyte mats covering the trunk and major branches. Longino collected from beneath these mats and found Bothriomyrmex workers and brood piles to be abundant beneath most of the mats. Large Margarodidae (Hemiptera, Coccoidea) were also scattered amongst the Bothriomyrmex . Other ant species occurred under the mats and were somewhat interdigitated with the Bothriomyrmex , although much less abundant. These included Hypoponera opacior , a small yellow Solenopsis , and Tapinoma . Smaller nests or aggregations were also found of Crematogaster sotobosque and Pheidole biconstricta . One part of the tree, near the pasture edge, was being invaded by Solenopsis geminata . I found only workers and brood. Ronald Vargas of Project ALAS collected more from the same tree in April. His collections included two adult males.

The second collection was also made in February of 2003. John Noyes of The Natural History Museum (London) was taking large sweep samples from vegetation at several Costa Rican localities and extracting Encyrtidae, his primary focal taxon. He also separated ants and sent these samples to Longino. Each sample contained hundreds to thousands of ants, including many alates. In the sample from Estación Cacao were about a dozen males and a similar number of dealate queens of Bothriomyrmex . The habitat at Estacion Cacao is a mosaic of mature montane moist forest with epiphyte-laden trees and abandoned pastures. This is a site on the Pacific slope of the northern-most cordillera in Costa Rica, 170km from the El Ceibo site on the Atlantic slope.

Comments: Although it is typical to choose workers as holotypes of ant species, we have chosen a queen because queens exhibit much greater morphological differences among species in Bothriomyrmex . This is true of several dolichoderine genera, including Azteca and Tapinoma . For example, Longino (1991) used queens as holotypes in taxonomic work on Azteca .

The new species undoubtedly belongs to the genus Bothriomyrmex . It has all the traits typical of the genus: 4:3 palp formula, strongly reduced hypostomal margin, and a characteristic venation on the forewing of the queen (closed discoidal cell, RM-2 absent, and radius reaching costal margin of wing). The systematics of the genus Bothriomyrmex are complex, and the previous classification (Dubovikoff, 2002) is not complete. Bothriomymex paradoxus belongs to Bothriomyrmex s.s. and not among the Asian and Australian species (Dubovikoff unpub.). However, it does not fit cleanly into one of the Palearctic species groups. The short suberect setae on the queen's mesosoma and gaster is a trait also found in members of the B. syrius group ( B. syrius Forel , B. turcomenicus Emery , B. communistus Santschi , B. kusnezovi Emery and B. urartus Dubovikoff ). However, B. paradoxus differs from all species of this group by the higher and shorter mesosoma of the queen. TI of B. paradoxus is 0.64, while other species have TI <0.50. Also, the impressed metanotal groove on the worker is a trait found in members of the B. gibbus complex and not in the B. syrius group.

Discussion

This is the first collection of the genus Bothriomyrmex in the New World. The occurrence in mature forest habitats and the fact that it is not conspecific with any known Old World species suggest it is truly native and not a recent introduction. Bothriomyrmex paradoxus may be a very old species, long isolated from the Palearctic species. Other putative relict species in Central America include Technomyrmex fulvus (Wheeler 1934) and Perissomyrmex snyderi (Longino and Hartley 1995). Central America appears to be a refuge for several ancient lineages of ants.

In the Palearctic, Bothriomyrmex s. s. are temporary social parasites of monogynous Tapinoma . It is unknown whether B. paradoxus is also a temporary social parasite of Tapinoma . Given its geographic isolation, elucidating the nest foundation behavior of B. paradoxus would be particularly valuable.