Fore wing hyaline; fore wing RS+Ma tubular on less than one third its length; anterior transverse carina of propodeum reaching the lateral margin; median tergites entirely pale.

Holotype: female. Body length 4.4 mm. Fore wing length 4.0 mm. Fore wing hyaline. Scutellar sulcus with three longitudinal carinae. Median areola of propodeum with well-defined margins. Anterior transverse carina of propodeum reaching the lateral margin. Lateral longitudinal carinae of median tergite 1 well-defined. Median syntergite 2+3 0.9 times longer than wide. Ovipositor longer than metasoma, but shorter than body.

Similar to holotype, but median tergites mostly pale with three posterior terga melanic.

Lytopylus mariamartachavarriae is named in honor of María Marta Chavarría in recognition of her participation in the collaborative development of the ICE-ACG geothermal project of Pailas II, northwestern Costa Rica.

Reared four times from Dichomeris santarosensis (Dichomeridinae, Gelechiidae) feeding on new leaves of Quercus oleoides (Fagaceae) in ACG dry forest at 305 m elevation.

Holotype ♀: Costa Rica, Guanacaste, Sector Santa Rosa, Arboles Via, Area de Conservaciόn Guanacaste 10.86081N -85.60828W 305m., Daniel H. Janzen coll., food plant: Fagaceae Quercus oleoides, host caterpillar: Gelechiidae, Dichomeridinae, Dichomeris santarosensis, coll. date: 6/24/1982, eclosion date unknown, DHJPAR0015502. Paratypes: [the following have the same data as the holotype except as indicated] 2♀, 1♂, DHJPAR0015501, DHJPAR0015503, DHJPAR0015500.