Holotype: female, “COLOMBIA: Boyacá: Arcabuco. Santuario de Fauna y Flora de Iguaque, Camino de la Laguna, 5°70'N, 73°46'W, 3400–3600m, emergió de celda en nido de Chilicola (Oroediscelis) sp. n. (Apoidea, Colletidae). Ese nido estaba en ramas secas de Espeletia argentea, 23 Agosto 2003, leg.V.González (UNCM)”.

This new species can be recognized from other described species of Grotea by the following combination of characters: gena close to the junction of occipital and hypostomal carinae with inwards genal projections (Fig. 8); propodeum with anterior transverse carina centrally weak and indented (Fig. 9); metasoma with tergite I slender but slightly shorter than mesosoma and rather straight (Figs 1, 3, 6); ovipositor shorter than the fore wing (Fig. 6).

Female. Fore wing 7.4 mm long.

Head in dorsal view with gena behind eyes rounded (Fig. 7); posterior ocellus separated from eye by 1.7 × its own maximum diameter (Fig. 7); genal projection present, laterally indistinct, ventroposteriorly evident; projection narrowing apically, horizontally oriented to inside of oral cavity; genal projections almost touching each other (Fig. 8); antenna with 35 flagellomeres (Fig. 6); flagellomere I 1.0 × as long as flagellomeres II and III combined. Epomia absent.

Mesosoma. Mesoscutum smooth with isolated inconspicuous punctures; scutellum in profile weakly convex; hind wing with Cu1 strongly pigmented, not reaching margin (Figs 5, 10); propodeum (Fig. 9) 2.1–2.2 × as long as broad; anterior transverse carina complete, centrally weak and indented, thus not forming a smooth arc from side to side (area basalis posteriorly enclosed); pleural carina complete; posterior transverse carina complete, although laterally weak; lateral longitudinal carina complete (area spiracularis enclosed); lateromedian longitudinal carina reaching anterior transverse carina, then absent; area lateralis not enclosed internally, rectangular, about 2.3 × as long as broad, with posterolateral corner at right angle removed from lobe surrounding coxal insertion. Area superomedia not differentiated, basally and distally weak, laterally open.

Metasoma. Tergite I (Figs 1, 3, 6) straight (not bowed upwards) and slender, shorter than mesosoma (mesosoma 1.5 × as long as tergite I); tergite I at least 4 times as long as broad posteriorly; visible part of ovipositor 2.7–2.9 × as long as hind tibia (Fig. 6).

Color. (Figs 1–5).

A predominantly black species with head with yellow circumocular area and clypeus. Pronotum with two longitudinal yellow spots, along ventral and dorsal margins, and a submedial red spot towards posterior margin. Mesopleuron mostly red with two large black areas, one at epicnemium and other towards posterior margin, and a yellow spot close to tegula. Mesoscutum with yellow longitudinal spots distally. Scutellum mostly brownish anteriorly. Propodeum with brownish area basalis, area superomedia with yellow central spot, yellow areae petiolaris, posteroexterna and spiracularis, dull yellow area lateralis. Metasoma with extensively yellow marked tergites. Dull yellow ovipositor sheath. Fore and mid legs with extensively yellow-marked coxae and femora. Hind leg with extensively red marked coxa and femur. Fore wing hyaline.

Pubescense. Gena, vertex, mesosoma and metasoma with dense, whitish setae, setae longer on propleuron, pronotum, mesopleuron and metapleuron.

The name of this new Grotea species refers to its uncommon pubescence.

The 12 described species of the Grotea anguina species-group have backwards-directed genal projections whilst Grotea villosissima sp. n. has inwards-projecting genal projections (Fig. 8).

The three described species of the Grotea chiloe species-group have an upwards bowed first tergite, whilst Grotea villosissima sp. n. has a straight first tergite (Figs 1, 3, 6).

The two described species of the Grotea gayi species-group lack genal projections, have a strong epomia and have a fully closed area superomedia. Grotea villosissima sp. n. has genal projections (Fig. 8), lacks epomia and has an incomplete area superomedia (Fig. 9).

Grotea superba, the only described species of the Grotea superba species-group, is similar to Grotea villosissima sp. n. in having a straight first tergite (Figs 1, 3, 6). However, Grotea superba has sharp downwards-projecting genal projections, 43 flagellomeres, 9.0–12.5 mm fore wing length, hind wing with a strongly pigmented Cu1 reaching the margin of the wing, and ovipositor always longer than the fore wing. Grotea villosissima sp. n. has inwards-projecting genal projections, 35 flagellomeres, 7.4 mm fore wing length, hind wing with Cu1 not reaching margin of the wing (Fig. 5, 10) and ovipositor shorter than the fore wing (Fig. 6). Finally, there are also clear differences in the color pattern between these two species (e.g. black flagellum with a white ring between flagellomeres 24 to 42 in Grotea superba and a black flagellum (Figs 1, 3) in Grotea villosissima sp. n.). All the differences between Grotea villosissima sp. n. and the described species of Grotea make the inclusion of this new species into any of the species-groups proposed by Wahl (1993) uncertain.

Grotea villosissima sp. n. is the first species of Grotea recorded from Colombia, where at least 5 more species of this genus occur (Gonzalez and Giraldo 2009).