Myrmelachista flavoguarea

An obligate inhabitant of an undescribed Guarea that occurs in the understory of wet forests.

Identification
Longino (2006) - Worker antenna 9-segmented, maxillary palpus 6-segmented, color yellow with darker gaster. Queen head orange, HW 1.17–1.24mm. Male with pygostyles present, basiparamere lobes and parameres very long and thin, digitus evenly tapered to apex. Obligate inhabitant of understory Guarea.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica.

Habitat
Known from Rio Peñas Blancas, at 800 m, in the Cordillera de Tilarán.

Biology
This species occurs in mature wet forest understory. It is an obligate inhabitant of an undescribed species of Guarea (Haber, pers. comm.). Most species of Guarea are large canopy trees; this species is an understory treelet, reaching reproductive maturity at 2–3m height. It is always a single stem from ground to shoot apex, with no lateral branches. Colonies of Myrmelachista occupy the entire stem, from ground level to the shoot apex. At Refugio Eladio in the Peñas Blancas Valley, the one site where I have collected M. flavoguarea, the tree is moderately common. Nearly every tree I have examined has contained M. flavoguarea, and I have never collected M. flavoguarea in any other situation. Thus, it appears to be an obligate inhabitant of this Guarea species.

There may be one or two physogastric colony queens. Occasional Coccoidea occur inside the stems. The only entrance holes are near the shoot apex. A few workers are occasionally seen on the surface near the shoot apex, but inside the stems are densely packed with hundreds of workers.

The biology of this species appears very similar to Myrmelachista flavocotea, Myrmelachista nigrocotea, Myrmelachista lauroatlantica, Myrmelachista lauropacifica, Myrmelachista osa, and Myrmelachista haberi, which are all obligate inhabitants of understory Lauraceae.

Nomenclature

 *  flavoguarea. Myrmelachista flavoguarea Longino, 2006a: 20, figs. 1, 6, 12, 13 (w.q.m.) COSTA RICA.

Worker
HL 0.636–0.865, HW 0.598–0.803, SL 0.308–0.376, EL 0.112–0.141, CI 93–99 (n=5).

Antenna 9-segmented; maxillary palpus 6-segmented; dorsal surface of mandible rugose; clypeus and face smooth; 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 short suberect setae, longer setae about half width of tibia; head and mesosoma yellow orange, gastral tergites with broad bands of infuscation.

Queen
HL 1.336–1.422, HW 1.170–1.242, SL 0.544–0.579, EL 0.289–0.321, OW 0.087–0.095, OD 0.161–0.185, CI 85–89, OI 25–27, OcI 6–7 (n=5).

Antenna 9-segmented; maxillary palpus 6-segmented; labrum short, bilobed, not covering mouthparts; dorsal surface of mandible punctatorugose; anterior face and clypeus faintly roughened, grading to smooth and shining posteriorly; in full face view, with abundant short subdecumbent setae projecting from rear margin and sides of head; ventral surface of head with abundant erect setae, many exceeding width of scape; 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 subequal to width of tibia; petiolar node broadly rounded in lateral view; head, and mesosoma including petiole yellow orange, gaster dark brown.

Male
Antenna 10-segmented; maxillary palpus 5 or 6-segmented; pygostyles present, sclerotized, setose; basiparamere lobe thin, pointed, about half the length of the paramere; paramere long, thin, with parallel sides; cuspis small, subrectangular, with series of small denticles at apex; digitus long, narrow, 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.

Type Material
Holotype queen: Costa Rica, Alajuela, Refugio Eladio, Rio Peñas Blancas, 10°19’N, 84°43’W, 800m, 23 Dec 1986 (J. Longino#1501) [, specimen code JTLC000002744].

Paratypes: all same locality as holotype, queens and workers; JTLC000002745, 27 Apr 1987 (J. Longino#1616) ; JTLC000002746, 28 Apr 1987 (J. Longino#1624) ; JTLC000002747, 20 May 1987 (J. Longino#1678) ; JTLC000006198, 22 May 1987 (J. Longino#1682) ; JTLC000006199, 30 Apr 1988 (J. Longino#2046).

Etymology
The name refers to the yellow color of the queen head and its association with the plant genus Guarea.