Myrcidris epicharis

Myrcidris epicharis is known to inhabit live swollen stems of a rainforest antplant, Myrcia sp. (Myrtaceae), in Amazonas, Brazil. It was originally discovered by Woody Benson, and was referred to as a "small timid Pseudomyrmex" living in Siparuna in his review (Benson, 1985) of Amazonian antplants. It is known from only a few sites in lowland rainforest north of Manaus. (Ward 1990)

Identification
Ward (1990) - M. epicharis bears some resemblance to the Tachigali-inhabiting species (Pseudomyrmex concolor complex) in the Pseudomyrmex viduus group. I assume the resemblance reflects a combination of convergent similarity (both being specialist plant-ants) and symplesiomorphy (the Pseudomyrmex viduus group being close to the inferred ground plan of the genus). It is interesting that the workers of both are frequently attacked by an external fungus (?Laboulbeniaceae).

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 *  epicharis. Myrcidris epicharis Ward, 1990: 467, figs. 1-6, 21-25, 29-32 (w.q.m.) BRAZIL.

Worker
Holotype. HW 0.58, HL 0.75, EL 0.27, PL 0.29, PH 0.23.

(n = 14). HL 0.65-0.79, HW 0.49-0.61, MFC 0.082-0. 102, CI 0.75-0.79, OI 0.67-0.74, REL 0.33-0.37, REL2 0.43-0.48, OOI 0.34-0.64, VI 0.76-0.86, FCI 0. 156-0.182, SI 0.40-0.46, SI2 0.85-1.07, FI 0.45-0.50, POI 0.78-0.93, MPI 0.039-0.075, NI 0.52-0.58, PLI 0.72-0.84, PWI 0.61-0.74, PWI3 0.56-0.65, PPWI 1.32-1.63.

A small species (HW 0.49-0.61) with head notably longer than broad; sides of head broadly convex, rounding into the occipital margin which is flat to weakly concave medially; frontal carinae separated by about maximum scape width; scapes bent proximally and enlarged distally, very short, subequal to or less than eye length; first funicular segment exceeding in length the next three segments combined; second and third funicular segments much broader than long (FLI 0.77-1.16), sometimes partly fused; the three ocelli very weak, usually reduced to slight pin-prick impressions; pronotum laterally rounded; fore-femur moderately swollen; propodeal spiracles laterally protuberant in dorsal view; petiole longer than high or wide, with a conspicuous anteroventral tooth and with a rather broad anterior peduncle; postpetiole markedly broader than long.

Outer surface of mandibles smooth and shiny, becoming stria to-punctate towards the masticatory margin. Head smooth and shiny on upper half, with widely scattered punctulae, becoming sublucid and much more densely punctulate anteromedially; opaque and densely coriarious-punctulate between the frontal carinae. Mesosoma dorsum smooth and shiny with scattered punctulae, laterally sublucid and imbricate-coriarious except for smooth areas on the propleuron and upper half of mesopleuron. Petiole, postpetiole and fourth abdominal (first gastric) tergite sublucid, covered with fine piligerous punctures. Appressed pubescence moderately dense on most of body except the smooth shiny areas on the head and mesosoma. Fine standing pilosity moderately common on scapes, gula, mesosoma dorsum (9- 15 hairs), petiole and postpetiole; absent or very sparse on gastric terga (excluding posterior margins), external face of mid- and hind-tibiae, sides of head (frontal view) and upper half of head (except for 1 pair of supraocular setae). Orange-brown, with weakly infuscated bands on posterior margins of gastric terga; head a little darker than mesosoma; appendages paler luteous, mandibles darker, ferrugineous brown.

Queen
(n = 6). HL 1.03-1.11, HW 0.68-0.73, MFC 0.119-0.131, CI 0.62-0.68, OI 0.69-0.75, REL 0.32-0.35, REL2 0.50-0.53, OOI 0.87-1.38, VI 0.93-0.98, FCI 0.164-0.191, SI 0.41-0.44, SI2 0.79-0.86, FI 0.48-0.51, NI 0.63-0.67, PLI 0.60-0.65, PWI 0.58-0.66, PWI3 0.67-0.75, PPWI 1.35-1.45.

Head elongate (CI = 0.65), subrectangular, with parallel sides and a concave occipital margin; median clypeal lobe subtriangular and protuberant; scape and funiculus similar to that of worker; ocelli (3) well developed; petiole more slender than that of worker (compare PLI and PWI values), with a larger anteroventral process, body sculpture paralleling that of worker; standing pilosity more common, especially on gaster and upper half of head. Dark castaneous brown, antennae, tibiae, and tarsi a contrasting luteous brown, femora intermediate.

Male
Small (HW = 0.60), with prominent compound eyes and ocelli; first funicular segment about one half the length of the second and succeeding segments which are subequal in length and do not become shorter distally; forefemur not swollen; petiole slender, lacking a distinct anteroventral tooth. Body more extensively smooth and shiny than in the worker; appressed pubescence and decumbent to suberect pilosity common. Dark brown, with contrasting paler appendages. See also generic diagnosis.

Type Material
Holotype worker. BRAZIL, Amazonas: Faz. Esteio, 80 km NNE Manaus, 80 m, 2"25'S, 59°46'W, 15. ix.1987, ex live terminal stem of Myrcia sp. (Myrtaceae), in INPA/WWF rainforest reserve (no. 1101) (P. S. Ward ace. no. 9146)

Paratypes. Same locality and date as holotype, P. S. Ward acc. nos. 9143-9148: series of workers, queens, and males, from different individual trees of Myrcia sp. ; BRAZIL, Amazonas: Res. Campina, near Manaus, 29.vii. 1979 ex Siparuna [= Myrcia sp.], (W. W. Benson acc. no. 26F) workers; Res. Campina, km 44, BR-174, near Manaus 27.viii.1979 ex Siparuna [= Myrcia sp.] (W. W. Benson acc. no. 50F) workers; E.E.S.T., km. 44.5, B R-174, near Manaus, 30.vii.l981, ex 7 m Siparuna [ = Myrcia sp.], (W. W. Benson acc. no. 370F) workers and queens; Reserva 1101, km 27, ZF-3, near Manaus 10.viii.1981 (W. W. Benson ) 1 worker. Paratypes deposited in, , , , , , , , , , , , , , , , , and W.W. Benson Collection.