Type material. Holotype, 1 female, COSTA RICA: Alajuela, Area de Conservación Guanacaste, Sector Rincon Rain Forest, Estación Llanura, lat 10.93332, long -85.25331, 135 m, 17.ix.2009, M. Moraga, 09-SRNP-75793, parasitoid voucher DHJPAR0039932. Paratypes: 2 males same data as holotype except for collecting dates and voucher codes as follow: 10.x.2009, 09-SRNP-76107, parasitoid voucher DHJPAR0039933; and 09.x.2009, 09-SRNP-76084, parasitoid voucher DHJPAR0039931. All specimens deposited in DHJWH temporarily, for later transfer to CNC.

Eyes silver mottled with gray, ocelli silver (Figs 1A–C, L). Curvature of pronotum with a deep groove that has semicircular rugae. Scutellar sulcus with five deep, carinated foveae of heterogeneous size (Figs 1E–F, M–N). Axillary trough of scutellum (ATS) with several parallel carinae that are close to each other (Figs 1F, M–N). Fore wing longer than body length.

Holotype female. Body length 4.56 mm, fore wing length 4.87 mm, hind wing length 3.99 mm

Coloration (Figs 1A–R). General body pale yellow, except posterior half of hind coxa with an infuscated ventral band (Fig. 1I). Flagellum, trochanter, trochantellus, apex of both femur and tibia brown, hind tarsi, and tarsal claws of all legs completely brown. Scape and pedicel yellow-brown. Eyes silver mottled with gray, ocelli silver (Figs 1A–C, L). Membrane and microtrichiae of both fore and hind wings light brown (Figs 1A, L).

Head (Figs 1B–C). Scape longer than wide (0.26:0.17 mm); pedicel wider than long (0.12:0.10 mm), first antennal flagellomeres not sub-equal in length (0.30:0.36:0.34 mm). Antennal scrobes deep, smooth, far above middle level of eyes (Fig. 1B), carinated dorsally (Fig. 1C); in frontal view, medial area between antennal scrobes with a sharp, short projection carrot-shaped (Fig. 1B), antennal scrobes in contact with inner eye margin (Fig. 1B). Face with small, sparse and homogeneous punctures, face with a median-longitudinal carina running from antennal scrobes to clypeus, fronto-clypeal suture absent (Fig. 1B). Distance between each anterior tentorial pit and closest inner compound eye margin equal to diameter of a tentorial pit (0.06:0.06 mm); anterior tentorial pits far away from each other (0.30 mm) (Fig. 1B). Mandible with two teeth, inferior tooth thinner, longer than superior. Maxillary palps longer than labial palps (Fig. 1B). Distance between a posterior ocellus and adjacent eye margin sub-equal in length equal to diameter of lateral ocellus (0.10:0.10 mm), distance between lateral ocelli shorter than diameter of lateral ocellus (0.06:0.10 mm) (Fig. 1C). Vertex narrow with small, sparse punctuations, but medially smooth and concave (Fig. 1C).

Mesosoma (Fig. 1A, D–F, L–N). Mesosoma dorsoventrally convex (Figs 1A, D). Pronotum shiny, smooth; curvature of pronotum with a deep groove that has semicircular rugae. Mesopleuron convex, extended, smooth except margins lateral and ventro-lateral that form a L-shaped area that possesses small, homogeneous punctuations (Fig. 1D), mesopleuron with a deep dent just above L-shaped area, dent with elongated foveae bordering the L-shape area, mesosternum slightly flat with distinctive groove of deep, homogeneous foveae. Metepisternum and metepimeron separated by a groove with several deep foveae throughout (Fig. 1D), metepisternum narrower than metepimeron, metepisternum just above hindcoxa outlined by a wide and flat carina, and apical half with several short cariane. Mesoscutum as wide as head with small and homogenous punctures. Notauli clearly impressed, broad, but not reaching the transscutal articulation (Fig. 1E). Scutellar sulcus with five deep, carinated foveae of heterogeneous size (Figs 1E–F, M–N). Scutellum shiny, almost smooth with sparse, fine punctures and surrounded by a strong carina (Figs 1E–F, M–N). ATS with several parallel carinae which are close to each other (Figs 1E, N). Axillary trough of metanotum (ATM) with a few, incomplete parallel carinae, only present basally (Figs 1E, N). Lunule of scutellum (L) and medioposterior band of scutellum (BS) smooth and shiny. Medioposterior band of metanotum (BM) short and crossed by a carina aligned with the median longitudinal carina of propodeum (Fig. 1F). Medioanteror pit of metanotum (MPM) hexagonal, and delimited by a strong carina (Fig. 1F). Posterior rim of metanotum (PRM) thin and smooth (Fig. 1F). Propodeum with a complete median-longitudinal carina dividing the propodeum in two halves, plus one divergent carina at each half of propodeum, area between carinae basally shorter than apically, divergent carinae crossed by semicircular carinae (Fig. 1F).

Wings (Figs 1A, L). Fore wing with vein r straight (0.30 mm) arising just beyond middle of pterostigma; vein 2RS as long as r (0.30:0.30 mm), but longer than 2M and (RS+M) b veins (0.30:0.15:0.20 mm). Hind wing with vannal lobe reduced, slightly convex; edge with sparse setae throughout. Costal and basal cell infuscate.

Legs (Figs 1A, I, L, O–R). Hind coxa surpassing apex of tergite III (Figs 1A, L, Q–R), outer dorsal surface of hind coxa delimiting an area surrounded by a strong longitudinal carina running from base to apex, but last third apically the carina turns inward (Fig. 1Q); that area with rugulose punctuations and with an extra strong basal carina inclined and reaching only the first third basally; hind tibia with outer spur half as long as inner spur (0.34:0.66 mm); inner spur more than half as long as hind basitarsus (0.66:0.90 mm) (Fig. 1P); hind tibia and hind tarsi both with spines throughout, hind tarsal claw with a short comb (Fig. 1O).

Metasoma (Figs 1G–H, J–K, Q–R). Petiole of tergite I narrow (Figs 1H, Q–R), length 0.56 mm, distinctly constricted at anterior half (minimum width 0.09 mm), but subapically wider (maximum width 0.25 mm) and with a few sculpturations, petiole with a deep groove extending more of two thirds tergite I length; hypopygium not protruding at apex of metasoma (Figs 1A, J); hypopygium plate with truncate apex (Fig. 1J), ovipositor sheath length 0.20 mm, glabrous, slightly protruding apex of metasoma (Fig. 1J).

Males (Figs 1K–R). Males differ in coloration from the female: lateral mesonotal lobes pale or dark brown (Figs 1M–N). Tergite II with a brown median area which is longer than wide (Figs 1Q–R); tergite III with a brown (Fig. 1Q) or yellow-brown area (Fig. 1R) anteriorly narrower than posteriorly; tergites IV brown but subapically with a thin transversal yellow apical band (Figs 1Q–R). The infuscate areas on hind legs are darker than in females (Fig. 1L). Antennae length = 5.0-5.2 mm, body length = 4.2-4.5 mm. Last antennal segment gradually narrowing at the apex. Tergite I, minimum width = 0.10 mm, maximum width = 0.22 mm, total length = 0.60-0.70 mm.

This species is named in honor of Dr. M. Alex Smith of the University of Guelph, Canada, in recognition of his decade of deep intellectual, laboratory and logistic support for the DNA barcoding of the parasitoid wasps and flies of ACG.

The species is only known from the original rain forest collection site, Sector Rincon Rain Forest, in Área de Conservación Guanacaste in northwestern Costa Rica. In 1999, ACG was inscribed as a UNESCO World Heritage site containing the best-preserved and regenerating dry forest habitats from Central America to northern Mexico.

Wilkinsonellus alexsmithi has been reared from the leaf-roller Microthyris prolongalis,Crambidae (Figs 2A, C–D) three times, while feeding on the rain forest leaves of Ipomoea phillomega or sweet potatoes Ipomoea batatas (Convolvulaceae) (http://janzen.bio.upenn.edu/caterpillars/database.lasso). The larva of Microthyris prolongalis lives inside of the leaf roll that it constructs, eating leaf tissue there. It is therefore likely that oviposition takes place through the leaf into the moth larva. The wasp cocoon (Fig. 2B) is lightly silked to the inner wall of the leaf roll and the larva dies at about the time that the wasp larva exits the cadaver.

The last three antennal segments are missing from the holotype. Wilkinsonellus alexsmithi is a parasitoid of a crambid leaf roller larva, Microthyris prolongalis (Crambidae). In ACG, this moth larva feeds only on Convolvulaceae (410 rearing records, Janzen & Hallwachs 2009). Within the subfamily Microgastrinae besides Wilkinsonellus, members of two other genera, Apanteles and Diolcogaster, are parasitoids only on this species of moth. The taxonomic range of insect parasitoids that use Microthyris prolongalis as a host entails two insect orders, Hymenoptera and Diptera. Within Hymenoptera the chalcidoid family Encyrtidae (genus not reported), and two additional subfamilies of Braconidae, Orgilinae (Stantonia) and Agathidinae (Alabagrus maya) were reported; for the Diptera parasitoids, two genera of Tachinidae, Actia and Argyrophylax also parasitize this caterpillar (Janzen and Hallwachs 2009).