Myrmelachista longiceps, Longino, J. T., 2006

Longino, J. T., 2006, A taxonomic review of the genus Myrmelachista (Hymenoptera: Formicidae) in Costa Rica., Zootaxa 1141, pp. 1-54 : 33-36

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Myrmelachista longiceps


Myrmelachista longiceps   HNS NEW SPECIES

Figures 5, 7, 8, 12, 14

Holotype alate queen: Costa Rica, Prov. Puntarenas, Monteverde , 10°18’N, 84°48’W, 1400m , 24 Jan 1996 (J. Longino #3743) [ INBC, specimen code JTLC000006219 ]. GoogleMaps

Paratypes: workers and queens, from same nest as holotype, specimen codes JTLC000006220 - JTLC000006224 , distributed to MCZC, USNM, UCDC, LACM, BMNH. GoogleMaps


Worker with antenna 9-segmented, color red brown. Queen with head black, elongate, CI 80-86. Male with digitus usually long and paddle-shaped with thickened posterodorsal margin.


Antenna 9-segmented; maxillary palpus 5-segmented but terminal segment elongate, sometimes with partial constriction suggestion partial fusion of terminal two palpomeres; dorsal surface of mandible weakly to strongly rugose or punctatorugose; clypeus and face smooth and shining with variable amount of roughening and larger puncta on anterior malar spaces and anterior clypeus; in full face view, side and rear margins of head with sparse to abundant appressed to subdecumbent pubescence, sometimes with a few projecting setae on posterolateral vertex; ventral surface of head with sparse to 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 subdecumbent setae, relatively uniform length, short, about 1/4 width of tibia; typically with dark brown head and gaster, mottled dark and light brown mesosoma, sometimes uniformly dark brown, never strongly bicolored.

Measurements: HL 0.593-0.779, HW 0.562-0.716, SL 0.312-0.384, EL 0.127-0.147, CI 89-95 (n=5).


Antenna 9-segmented; maxillary palpus 5 or 6-segmented; dorsal surface of mandible moderately to strongly punctatorugose; clypeus and anterior malar spaces roughened and with large puncta, grading to smooth and shining with smaller puncta posteriorly; 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, short, about 1/4 width of tibia; color largely black, sometimes with some degree of lighter red color on anterior face.

Measurements: HL 1.096-1.270, HW 0.904-1.078, SL 0.470-0.551, EL 0.281-0.330, OW 0.045-0.079, OD 0.187-0.232, CI 80-86, OI 29-33, OcI 4-7 (n=10).


Antenna 10-segmented; maxillary palpus 5 or 6-segmented; pygostyles absent; basiparamere with long, needle-like lobe; paramere very elongate and linear, with parallel sides; apodeme of penial valve curving into dorsal margin at obtuse angle. Volsella variable as follows: (collection JTL2280) cuspis very short, closely applied to inner surface of paramere, paddle-shaped, apex with a row of small denticles, only apical row of denticles sclerotized; digitus with short, narrow, downcurved base where dorsal margin close to cuspis, then expanding into large paddle-shape structure, dorsal margin revolute and thickened, forming bulla, large lamina of digitus with several irregular thin spots; (JTL2696) cuspis very short and narrow, parallel sided, distant from digitus, digitus broadly and bluntly scimitar-shaped, but not as grossly expanded, without revolute margin or bulla, irregular thin spots small, faint; (JTL2620) cuspis like JTL2696; digitus like a shorter version of JTL2696, with apical margin greatly thickened and forming pair of bulla, shiny and cream-colored on dried specimen; lamina of digitus lacking thin spots.


The name refers to the relatively elongate head of queen and worker.


Costa Rica. In Costa Rica it occurs throughout the country in mature wet forest habitats, most commonly from 500-1500m elevation but occasionally lower.


This species occurs in mature wet forest habitats, most commonly in montane forests but occasionally lower. It nests in live stems of various plant species. Nests have been found in the live stems of a 2m tall shrub in the Rubiaceae, a large Palicourea-like shrub, Guarea rhopalocarpa , Ocotea   HNS , Licaria , Ocotea whitei , Conostegia , and Ficus . Founding queens have been found in Guarea (the undescribed species usually inhabited by M. flavoguarea   HNS ), in chambers in terminal shoots of sprouts from the base of a G. rhopalocarpa tree, in a small Inga sapling (adjacent to a large mature colony in a Licaria tree), and in a shrub in the Rubiaceae. Coccoidea often occur in the stems.


One collection is very similar to longiceps   HNS in many respects, but is an outlier with respect to queen size (Fig. 7). The queen is much smaller than any longiceps   HNS queen. It is currently assigned the morphospecies code JTL-022. It is based on one collection from Refugio Eladio in the Peñas Blancas Valley, Cordillera de Tilarán, Costa Rica. Workers and queens were collected from live branches of a Lonchocarpus   HNS tree that had been knocked over by a small landslide. The colony was polygynous, with many dealate queens. There were also Coccoidea with the ants in the stems. The measurements of a queen from this collection are: HL 0.914, HW 0.715, SL 0.416, EL 0.237, OW 0.040, OD 0.178, CI 78, OI 33, OcI 4 (n=1).

Material Examined

COSTA RICA, Alajuela: Refugio Eladio, Rio Penas Blancas , 10°19’N, 84°43’W, 800m (J. Longino, 5 collections) GoogleMaps ; Rio Agua Gota , 10°23’N, 84°42’W, 1100m (E. Bello) GoogleMaps ; 2km N Volcan Arenal , 10°29’N, 84°42’W, 600m (J. Longino) GoogleMaps ; Guanacaste: Estacion Cacao , 10°55’N, 85°30’W, 1100m (J. S. Noyes) GoogleMaps ; Heredia: Refugio El Plastico, 17km S Pto. Viejo , 10°18’N, 84°02’W, 550m (J. Longino, 3 collections) GoogleMaps ; 22km N Volcan Barba , 10°20’N, 84°04’W, 500m (J. Longino) GoogleMaps ; La Selva Biological Station , 10°26’N, 84°01’W, 50m (ALAS) GoogleMaps ; 16km SSE La Virgen , 10°16’N, 84°05’W, 1100m (ALAS, R. Vargas C, M. Paniagua, D. Brenes, J. Longino, multiple collections) GoogleMaps ; Puntarenas: Monteverde , 10°18’N, 84°48’W, 1500m (Yanoviak & Gering, multiple canopy fogging samples) GoogleMaps ; same data (J. Longino) GoogleMaps ; Wilson Botanical Garden, 4km S San Vito , 8°47’N, 82°58’W, 1200m (J. Longino) GoogleMaps ; 3km W Las Alturas , 8°56’N, 82°52’W, 1360m (J. Longino) GoogleMaps ; Fila Cruces, nr San Vito , 8°47’N, 83°03’W, 1200m (J. Longino) GoogleMaps ; San José: Carrillo, Braulio Carrillo Nat. Park , 10°09’N, 083°55’W, 500m (J. Longino) GoogleMaps .


Costa Rica, Santo Domingo de Heredia, Instituto Nacional de Biodiversidad (INBio)


USA, Massachusetts, Cambridge, Harvard University, Museum of Comparative Zoology


USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]


USA, California, Davis, University of California, R.M. Bohart Museum of Entomology


USA, California, Los Angeles, Los Angeles County Museum of Natural History


United Kingdom, London, The Natural History Museum [formerly British Museum (Natural History)]













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