Myrmelachista joycei

An abundant inhabitant of Costa Rican cloud forests.

Identification
Longino (2006) - Worker with antenna 9-segmented, color red brown. Queen with head black, mandible and clypeus usually smooth and shiny, HW 70.5–1.08mm, CI 87–98, OcI 3–6. Male with digitus elongate, curving, scimitar-shaped.

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

Habitat
In Costa Rica it occurs in cloud forest above 1000m, from the Cordillera de Tilarán south to the Cordillera de Talamanca. There is also a record of a queen from cloud forest near Matagalpa, Nicaragua.

Biology
Longino (2006) - This species is very abundant in cloud forest. It nests in live branches of canopy trees, with columns extending out in galleries beneath epiphyte mats. It is one of the most common arboreal ants in the Monteverde cloud forest, occurring in a high frequency of tree crowns (Longino 2000) and common in canopy fogging samples (Schonberg et al. 2004). Active colony space occurs in hollow stems near shoot tips, but also extends far back in the centers of live branches, such that workers may be found in narrow chambers deep in the center of relatively thick branches, to 10cm diameter or more. Periodic larger chambers contain dense masses of workers, queens, and brood and may be well-protected deep in solid wood. Clusters of workers and brood also occur beneath epiphytes and in small bits of dead wood. Colonies are large and may occupy an entire tree crown. Large colonies are strongly polygynous, with clusters of physogastric queens scattered throughout the colony space. Pseudococcidae and Coccidae commonly occur in the nests and in the surface galleries beneath epiphytes. Colonies have been found in live branches of Sapium oligoneuron, Vismia, Clusia alata, Cecropia angustifolia (formerly polyphlebia), Ficus, Ocotea austinii, hemiepiphytic Araleaceae, Licaria, and Erythrina. A founding queen was found in a live stem of an orchid.

Nomenclature

 *  joycei. Myrmelachista joycei Longino, 2006a: 25, figs. 2, 5, 7, 8, 10, 14 (w.q.m.) COSTA RICA.

Worker
HL 0.556–0.655, HW 0.556–0.670, SL 0.302–0.352, EL 0.114–0.137, CI 100–107 (n=5).

Antenna 9-segmented; maxillary palpus 5-segmented but terminal segment elongate, sometimes with partial constriction suggestion partial fusion of terminal two palpomeres; mandible, clypeus, and face smooth and shining; in full face view, side and rear margins of head with sparse to abundant subdecumbent pubescence, sometimes with projecting setae on posterolateral vertex; ventral surface of head with very abundant short subdecumbent pubescence, no erect setae; scape with abundant suberect setae, longer setae about equal to width of scape; hind tibia with abundant appressed to suberect setae, relatively uniform length, about 1/4 to 1/2 width of tibia; typically with dark brown head and gaster, mottled dark and light brown mesosoma, sometimes uniformly dark brown, never strongly bicolored (nanitics may be bicolored).

Queen
HL 0.793–1.124, HW 0.747–1.083, SL 0.395–0.531, EL 0.213–0.269, OW 0.024–0.069, OD 0.176–0.220, CI 87–98 (87 for specimen from northern Nicaragua, 89–98 for Costa Rican material), OI 25–29, OcI 3–6 (n=12).

Antenna 9-segmented; maxillary palpus 6-segmented; dorsal surface of mandible smooth and shining with sparse piligerous puncta or weakly punctatorugose; clypeus and face largely smooth and shining with sparse small piligerous puncta; in full face view side and rear margins of head with abundant short appressed to suberect pubescence, without longer erect setae, sometimes with longer erect setae on posterolateral vertex; ventral surface of head with abundant subdecumbent to suberect setae, these similar to or longer than setae on sides of head; scape with abundant suberect setae, longer setae about equal to width of scape; hind tibia with abundant appressed to suberect setae, relatively uniform length, about 1/4 to 1/2 width of tibia; color largely black, sometimes with some degree of lighter red color on anterior face.

Male
Antenna 10-segmented; maxillary palpus 6-segmented; pygostyles minute, in the form of weakly sclerotized papillae; basiparamere with elongate lobe; paramere elongate and linear, with parallel sides; cuspis a small, weakly sclerotized narrowly triangular tooth appressed to the inner surface of the paramere, distant from digitus; digitus elongate, curving, scimitar-shaped; apodeme of penial valve curving into dorsal margin at obtuse angle.

Type Material
Holotype queen: Costa Rica, Prov. Puntarenas, Monteverde, 10°18’N, 84°48’W, 1500m, 29 May 1990 (J. Longino#2707), specimen code JTLC000006202. Paratypes: workers and queens, from same nest as holotype, specimen codes JTLC000002769, JTLC000006203-JTLC000006206, distributed to, , , ,.

Etymology
The name refers to Frank Joyce, Monteverde biologist and teacher, indefatigable field naturalist, champion for the conservation of tropical biodiversity, and respected friend.