Myrcidris

The genus Myrcidris was described from a single species, Myrcidris epicharis Ward, originally discovered by Woody Benson, and found to inhabit the live hollow stems of an Amazonian ant-plant in the genus Myrcia (Ward, 1990). A few stray workers of a second, undescribed (but closely related) species were recently collected in Guyana by Ted Schultz.

Identification
Ward (1990) - The unique features of workers and queens of Myrcidris are the 11-segmented antennae, single proximal tooth (and no others) on the basal margin of the mandibles, the particular configuration of ventral mandibular ridges, and the presence of fine, attenuate, apically bent setae on the upper medial surface of the clypeus. Also characteristic are the four teeth on the masticatory margin of the mandibles; non-truncate upper surface of the median clypeal lobe; laterally extended median lobes of the antennal sclerites; and well-developed mid and hind basitarsal sulci. Distinguishing features of males are the 13-segmented antennae; apically bent clypeal setae; convex posterior margin of sternum VIII; sclerotized attachment of the pygostyles to tergum X; membranous internal face of the paramere behind the mesial dorsoventral lobe; and presence of cornuti on the external face of the inner valve (aedeagus).

Nomenclature

 *  MYRCIDRIS [Pseudomyrmecinae: Pseudomyrmecini]
 * Myrcidris Ward, 1990: 465. Type-species: Myrcidris epicharis, by original designation.

Diagnosis, worker. Monomorphic, and relatively small in size (HW 0.49- 0.61 in the only known species). Mandibles with distinct basal and masticatory margins, the former shorter than the latter (MD5/MD9 = 0.75); both underlain ventrally by ridge lines which meet angularly at the apicobasal tooth; basal margin with a single, rather weak, proximal tooth; m asticatory margin with four evenly spaced teeth, increasing in size towards the apex. Palp formula: 5,3. Distal margin of labrum with a broad v-shaped cleft; labrum without prominent teeth or protuberances. Median clypeal lobe broadly rounded anteriorly; upper surface continuous, non-truncate and with several finely attenuate, apically bent setae, directed anteriorly. Number of antennal segments: 11 (with partial fusion of the second and third funicular segments in the only known species); scapes short (SI = 0.42); funiculus swollen apically as an indistinctly 4-segmented club. Median lobes of antennal sclerites rather well developed laterally (AS I = 0.90). Frontal carinae relatively well separated (MFC twice or more the basal scape width). Compound eyes with long axis directed anterolaterally, not exceptionally elongate (012 = 0.70). Ocelli (3) present but very small. Metanotal groove distinctly impressed; basal face of propodeum slightly shorter than, and rounding gently into, declivitous face. Propodeal spiracle elliptical. Two tarsal claws; mid and hind tibiae both with a well-developed pair of apical spurs; mid and hind basitarsal sulci present, well-developed. Petiole relatively short and high (PLI = 0.76), with short, broadly attached anterior peduncle. Median connection of spiracular plate (of sting apparatus) sclerotized.

Diagnosis, queen. Deciduously winged; agreeing with most of the foregoing worker traits, except median clypeal lobe more protuberant; head and petiole more elongate. Forewing with two cubital cells.

Diagnosis, male. Masticatory margin of mandibles with 3 teeth. Palp formula: 5,3. Median clypeal lobe broadly convex anteriorly, adorned with several fine, apically bent setae. Antennae 13-segmented, with a short scape (subequal in length to second funicular segment). Notauli absent; parapsidal lines lightly impressed. Basitarsal sulci lacking. Claws and tibial spurs as in the worker. Posterior margin of sternum VIII slightly convex; posterior margin of sternum IX (subgenital plate) broadly rounded; tergum VIII (pygidium) apicomedially constricted and emarginate. Pygostyles with a rigid, sclerotized connection to remnants of terga IX and X. Parameres narrowing apically, but with a distinct posterodorsal lobe, and a mesial dorsoventral lobe on the inner surface. Internal face of paramere predominantly membranous (unsclerotized) distal to the volsella and proximal to the mesial dorsoventral lobe. Volsella reduced to a small, setose, finger-like lobe. External face of inner valve (aedeagus) adorned with cornuti; internal face with flat plate-like surface separated from dorsal margin by a membranous groove. Antennae in the pupal stage lying ventrally below the mandibles.