Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Queen in images above is holotype.
Additional images:
Queen, lateral view with wings (large); holotype label (large). Male, face view (large); genitalia (large).
Range
Costa Rica. In Costa Rica it occurs throughout the Atlantic slope, from 50-1000m elevation. In Guanacaste Conservation Area it also occurs at 600m on the Pacific slope (Estaci—n Maritza).
Identification
Diagnosis: Worker antenna 9-segmented, maxillary palpus 5-segmented, color yellow. Queen head orange, eyes relatively small (OI 27-31), HW greater than 0.8mm. Obligate inhabitant of understory Lauraceae.
Worker: Antenna 9-segmented; maxillary palpus 5-segmented; dorsal surface of mandible shiny, weakly striatopunctate; clypeus and face smooth and shining; in full face view, with abundant short subdecumbent setae projecting from rear margin and sides of head, cluster of longer setae on posterolateral vertex; ventral surface of head with abundant short subdecumbent setae; scapes with abundant erect to subdecumbent setae, longer setae subequal to width of scape; outer surface of hind tibia with abundant erect to subdecumbent setae, longer setae about 2/3 width of tibia; color uniformly yellow orange.
Measurements: HL 0.591-0.688, HW 0.585-0.700, SL 0.306-0.328, EL 0.105-0.133, CI 98-103 (n=5).
Queen: Antenna 9-segmented; maxillary palpus 5 or 6-segmented; labrum short, bilobed, not covering mouthparts; dorsal surface of mandible punctatorugose; face and clypeus smooth and shining; in full face view, with abundant short erect to suberect setae projecting from rear margin and sides of head; ventral surface of head with abundant short erect setae; scapes with abundant erect to suberect setae, longer setae subequal to width of scape; outer surface of hind tibia with abundant erect to subdecumbent setae, longer setae shorter than width of tibia; color light yellow orange with infuscated bands on gastral terga, these bands occasionally lacking, rarely (one collection from La Selva Biological Station) color light red.
Measurements: HL 0.965-1.167, HW 0.861-1.079, SL 0.420-0.507, EL 0.260-0.304, OW 0.058-0.112, OD 0.168-0.222, CI 86-96, OI 27-31, OcI 6-10 (n=13).
Male: Antenna 10-segmented; maxillary palpus 6-segmented; pygostyles minute, weakly sclerotized; basiparamere lobe and paramere elongate, tapering; cuspis small, subrectangular, with series of about 3 tiny denticles at apex; digitus large, scimitar-shaped, broadly curved, with a series of tiny denticles on dorsal margin at contact point with apex of cuspis; apodeme of penial valve curving into dorsal margin at obtuse angle; ocelli relatively large; width of median ocellus about equal to or greater than distance from median to lateral ocellus; distance between lateral ocelli about equal to distance from lateral ocellus to compound eye.
Natural History
Myrmelachista flavocotea is an obligate inhabitant of understory treelets in the genus Ocotea. The first known collection of the species was by Nevermann in 1925, at Hamburg Farm, a site in Lim—n province. The specimens are at USNM and the label states "ex live stems with Coccoidea." An additional 43 records of the species have all been from live stems of Lauraceae. Most collections have been from Ocotea atirrrensis and O. dendrodaphne, common understory species that are mature at 1-3m height. Although workers of M. flavocotea cannot be distinguished easily from workers of several other species, the collections made by Jean Stout at La Selva (Stout 1979) were probably this species. They were from "Ocotea pedalifolia," an early misidentification of La Selva plants later identified as O. atirrrensis and dendrodaphne (Hammel 1986). Subsequent collections of Myrmelachista from understory Ocotea at La Selva have all been M. flavocotea. Less commonly colonies have been collected from O. tenera, another short-statured understory species.
Founding queens have been collected in stump sprouts of other Lauraceae that become large canopy trees, but no large trees have ever been found hosting a colony of M. flavocotea. Thus the species that become large trees must be unsuitable hosts for some reason and their colonization by founding queens accidental or an act of desperation resulting from unavailability of more suitable hosts.
Colonies are typically monogynous, although occasionally two physogastric queens occur in the same colony. All stem space of the treelets is occupied, from ground level to the tips of all the branches. Colonies contain hundreds to thousands of workers. New alate queens and males are produced gradually in the upper stems.
Low densities of Pseudococcidae are usually present in the stems. Although referred to above as "colonies" in individual trees, the species may be unicolonial. Workers will fight and grapple with allospecific workers (e.g. M. nigrocotea) but not with conspecific workers, even if workers are mixed from trees up to a kilometer apart. In contrast, other Myrmelachista species show intraspecific aggression among nests in separate trees.
Literature Cited
Hammel, B. E. (1986). The vascular flora of La Selva Biological Station, Costa Rica - Lauraceae. Selbyana 9, 218Ð233.
Longino, J. T. (2006). A Taxonomic review of the genus Myrmelachista (Hymenoptera: Formicidae) in Costa Rica. Zootaxa 1141:1-54.
Stout, J. (1979). An association of an ant, a mealy bug, and an understory tree from a Costa rican rain forest. Biotropica 11, 309Ð311.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
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