Revision of the new world genus Crassomicrodus Ashmead (Hymenoptera, Braconidae, Agathidinae), with an identification key to species

Abstract A key to species and descriptions are presented for 14 species of the New World genus Crassomicrodus Ashmead. Seven new species, Crassomicrodus azteca, Crassomicrodus clypealis, Crassomicrodus costaricensis, Crassomicrodus jalisciensis, Crassomicrodus mariae, Crassomicrodus oaxaquensis,and Crassomicrodus olgae are described. Crassomicrodus fenestratus (Viereck) is synonymized with Crassomicrodus nigriceps (Cresson). Crassomicrodus melanopleurus (Ashmead) is recognized as a valid species.

Male. Similar to female. Host. Unknown. Distribution. Canada, Mexico, and USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median transverse elevation, anterolateral edges of scutellum with a small acute projection, groove between lateral ocelli with small foveolae, and head and mesosoma black with some areas yellowish-orange.
Remark. This species is near to C. nigrithorax, but differs in that C. nigrithorax has the mesosoma black; anterolateral edges of scutellum lacking small acute projection; eye height 0.69-0.70× inter-ocular distance; malar space 0.38-0.47× longer than eye height; inner spur of middle tibia 0.89-0.95× length of basitarsus; and scutellar disc convex with sparse setae from 0.14 to 0.15 mm in length.
Male. Similar to female, but the posterior surface of antennal sockets smooth.

Diagnosis.
Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, malar space 0.60-0.63× as long as eye height, setae at base of mandible slightly longer than setae on rest of body surface, body length 5.20-5.50 mm, head and mesosoma black, and forewing slightly infumate.
Remarks. This species is similar to C. nigrithorax, but differs in that C. nigrithorax has gena bulging; area between antennal sockets with a median transverse elevation; groove between lateral ocelli with small foveolae; and malar space 0.38-0.47× longer than eye height.
Male. Similar to female, except antenna with 36 to 41 flagellomeres and pronotum may be slightly melanic.
Host. Unkown. Distribution. USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, length of ventrolateral margin of clypeus distinctly longer than diameter of tentorial pit, and gena slightly bulging.
Remarks. This species is near to male of C. fulvescens, but differs in that C. fulvescens has the length of ventrolateral margin of clypeus similar to the diameter of the tentorial pit; gena distinctly bulging; and forewing infumate with a large hyaline spot in first submarginal cell.
Etymology. Named "clypealis" to emphasize that the ventral margin of the clypeus is longer than the diameter of each tentorial pit.
Male. Unknown. Host. Unknown. Distribution. Costa Rica and El Salvador. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, eye height 0.75-0.77× inter-ocular distance, antenna with 41 flagellomeres, body length 8.10 to 8.70 mm, hind wing vein 1M 1.01-1.08× longer than 1r-m, head and mesosoma black, metasoma dark brown, and wings strongly infumate.
Remark. Specimens from Costa Rica are homogeneous in their measurements, but the specimen from El Salvador differs significantly. Nonetheless it is considered conspecific here due to similarity in other characters. More specimens and molecular data should easily test this hypothesis in the future.

Male. Unknown.
Host. Unknown. Distribution. Canada, Mexico, and USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, malar space 0.78-0.83× as long as eye height, scutellar disc sloped posteriorly and flattened, head black and mesosoma mostly black with some areas reddish yellow.
Host. Unknown Distribution. Mexico. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, posterior surface of antennal sockets rugulose, face setose, setae at base of mandible slightly longer than setae on rest of body surface, subalar lobe separated from mesopleuron by wide rugulose groove, and mesosoma mostly yellowish orange with wings infumate.
Remark. This species is near C. oaxaquensis, but differs in that C. oaxaquensis has the mesosoma black; wings hyaline; face with a weak longitudinal ridge dorsomedially; area between antennal sockets with a median pyramidal-shaped elevation and two weakly defined tubercles. One specimen of C. jalisciensis has the head and mesosoma black, but differs from C. oaxaquensis by leg and wing coloration.
Etymology. C. jalisciensis refers to the state of Jalisco, where all specimens have been found.
Host. Unknown Distribution. USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, frons not excavated, antenna with 25 flagellomeres, notauli not impressed, length of ovipositor sheath 0.76-0.78 mm, forewing vein R1 0.48-0.50× as long as vein RS, head and mesosoma black, and wings lightly infumate.
Remarks. This species is near to C. muesebecki, but differs in that C. muesebecki measures 6.08 a 6.95 mm, area between antennal sockets with a median transverse elevation and two weakly defined lateral tubercles, frons deeply excavated, antenna with 28-29 flagellomeres, pronotum more smooth, sparse setae on scutellar disc from 0.18 to 0.20 mm in length, length of ovipositor sheath 1.83-2.33 mm, and coloration of metasoma is black.
Etymology. This species is named in honor of María Espinosa Morales, wife of the first author.

Distribution. Mexico and USA.
Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, head transverse in frontal view, gena bulging, inner spur of middle tibia 0.77-0.86× length of basitarsus; inner spur of hind tibia 0.60-0.72× length of basitarsus, and body mostly yellowish orange with wings infumate.
Remarks. This species is difficult to circumscribe, the head shape and general coloration have a wide range of variation. We found some specimens with the head triangular in frontal view but they have the forewing infumate with a hyaline spot on the first submarginal cell, that occupies most of the space of the cell. Muesebeck (1927) suggested that the species could represent males of C. fulvescens. However the type of M. melanopleurus does not correspond to the characters of C. fulvescens, therefore we consider it to be a valid species. Crassomicrodus melanopleurus is very similar to C. fulvescens, but differs in that C. fulvescens has the gena distinctly bulging; frons deeply excavated; lateral scutellar depression rugose and foveolate; carinae of central metanotal defining an almost circular cell; inner spur of middle tibia 0.54-0.58× length of basitarsus; inner spur of hind tibia 0.48-0.54× length of basitarsus; and metapleuron completely reticulate-rugose. Description female. Body. Length. 6.08-6.95 mm. Color (Fig. 9e). Integument black except yellowish orange as follows, femora, one-fourth basal area of hind tibia, fore and middle tibia with its tarsomeres; medial areas of mandible yellow reddish; eyes silver or blackish; ocelli translucent yellow; medial area of hind tibia pale yellow, apical area of hind tibia with its tarsomeres blackish; wing veins dark brown; forewing slightly infumate with a hyaline spot on the first submarginal cell that is similar in size to the parastigma. Head (Fig. 9ab). Transverse in frontal view; face with weak longitudinal ridge dorsomedially; eye height/width = 1.41-1.45; eye height 0.61-0.62× inter-ocular distance; area between antennal sockets with a median transverse elevation and two weakly defined lateral tubercles, sometimes tubercles not defined; frons deeply excavated with two or more foveolae on center, posteriorly continue a pair of smooth groove that diverge towards the ocellar area, sometimes microfoveolate; posterior surface of antennal sockets smooth; groove between lateral ocelli smooth; median ocellus separated from lateral ocellus by smooth groove; gena distinctly bulging; malar space 0.46-0.50× as long as eye height; clypeus 2.30-2.50× wider than high; length of ventrolateral margin of clypeus similar to diameter of tentorial pit; antenna with 28-29 flagellomeres; setae at base of mandible similar on size than setae on rest of body surface. Mesosoma (Fig. 9cde). Pronotum smooth with abundant setae on pronotal groove and lateral pronotal area; lateral pronotal margins with weakly crenulate groove; notauli not impressed; anterolateral edges of scutellum lacking small acute projection; scutellar disc convex with sparse setae from 0.18 to 0.20 mm in length; scutellar disc sloped posteriorly and rounded; lateral scutellar depression microfoveolate centrally, with rugosities and foveolae on the margins; carinae of central metanotal area almost circular shaped; propodeum reticulate rugulose, more pronounced on lateral margins; subalar lobe separated from mesopleuron by narrow rugose reticulate groove, width distinctly shorter than the subalar lobe; three-fourth dorsal area of metapleuron smooth, rest reticulate-punctuate. Legs. Inner spur of middle tibia 0.72-0.86× length of basitarsus; inner spur of hind tibia 0.59-0.67× length of basitarsus; metabasitarsus 1.03-1.18× length of tarsomeres III, IV, and V combined; hind tibia 2.63-2.81× longer than basitarsus; hind femur length 3.09-3.33× its maximum width. Wings. Forewing length/width = 2.51-2.53; stigma 2.62-3.00× longer than maximum width; forewing vein R1 0.59-0.64× as long as vein RS; vein RS not sinuate; vein r arising at middle of stigma; second submarginal cell triangular, with petiole 0.04-0.11 mm long; vein M+CU not pigmented throughout; hind wing length/width = 3.26-3.44; hind wing vein 1M 1.66-1.76× longer than 1r-m; hind wing with 4-5 hamuli. Metasoma. Apical width of petiole (tergum 1) 1.78-2.11× wider than basal width; minimum width of petiole 0.67-0.70× apical width; length of ovipositor sheath 1.83-2.33 mm.
Male. Similar to female. Host. Unknown. Distribution. USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median transverse elevation, gena distinctly bulging, setae at base of mandible similar on size than setae on rest of body surface, notauli not impressed, scutellar disc convex with sparse setae from 0.18 to 0.20 mm in length, length of ovipositor sheath 1.83-2.33 mm, and body black with wings slightly infumate.
Remarks. C. muesebecki Marsh was described with observations on 14 specimens. In this revision, we included 13 of these, one homotype and 14 additional specimens. With the inclusion of these new specimens we confirm Marsh's (1960) observation that specimens from central and northern California have infumate wings, and in almost all the hind tibiae are yellowish orange, whereas the more southern specimens have hyaline wings and the medial areas of hind tibiae pale yellow. The species status of these two groups is tentative.
Male. Similar to female. Host. Unknown.
Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, head triangular in frontal view, face with a few sparce setae, setae at base of mandible distinctly longer than setae on rest of body surface, antenna with 37-43 flagellomeres, body usually with some areas yellowish-orange and wings infumate.

Crassomicrodus nigrithorax
Male. Similar to female except metasomal tergite has the color dark brown, antenna with 39 or 40 flagellomeres, and hind wing with 4 or 5 hamuli.
Host. Unknown. Distribution. Mexico. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, head triangular in frontal view, posterior surface of antennal sockets rugulose, face very setose, setae at base of mandible slightly longer than setae on rest of body surface, subalar lobe separated from mesopleuron by wide rugose groove, head and mesosoma black, and wings almost hyaline.
Remarks. This species is near to C. jalisciensis, but differs in that C. jalisciensis has areas of mesosoma yellowish orange, wings infumate, face without longitudinal ridge dorsomedially, and a median elevation between antennal sockets without defined lateral tubercles.
Etymology. C. oaxaquensis is after Oaxaca, in reference to the known geographical distribution of the species.

Crassomicrodus olgae
Male. Similar to female. Host. Unknown. Distribution. Mexico and USA. Diagnosis. Distinguished from other Crassomicrodus species by the following combination of characters: area between antennal sockets with a median pyramidal-shaped elevation, head triangular in frontal view, malar space 0.77-0.86× as long as eye height, body length 4.20-6.48 mm, forewing vein R1 0.47-0.57× as long as vein RS, body usually yellowish-orange.
Remarks. Crassomicrodus pallens resembles C. divisus in the shape of the head, but differs by the characters in the key. A few specimens of this species have the malar space shorter than eye height (0.77 times), specimens with this variation also have R1 less than 0.57 times as long as vein RS.