Megischus mexicanus Aguiar, 2006

Aguiar, Alexandre P., 2006, The Stephanidae (Hymenoptera) of Mexico, with description of six new species and key to western Foenatopus Smith, Zootaxa 1186, pp. 1-56 : 39-43

Megischus mexicanus Aguiar , sp. n.

( Figs 9–16 , 24 , 87–95 )

Etymology Named after the country of Mexico, as the most characteristic stephanid species of this region.

Description

FEMALE. Holotype specimen ( Figs 24 , 87–91, 93, 95 ). Body length 10.5 mm. Head: Antenna with 30 flagellomeres, f1 ventrally dilated, laterally flattened; f2 ventrally on central 0.3 perceptibly swollen; f3–6 very long and narrow, about 15 times as long as wide; f7 basal 0.3 cylindric, apical 0.7 somewhat widened; f8–25 as wide as f7 apex; f26–30 progressively shorter and smaller. Flagellomeres 1–6 corresponding to 0.35 of the flagellar length; width widening of apical portion of flagellum distinct, clearly dividing antennae in two major sections. Frons rugose approximately in zig­zag, ventrally rugosity transverse, changing to dorsally oblique. Coronal tubercles well defined, hind tubercles mesal margin widely separated, ending at anterior margin of first interocellar carina. Vertex ( Fig. 87 ) glabrous; two interocellar carina, first one strong, darkened, shaped as a square bracket (“[”), second weak, more irregular; main area densely transversely rugose, changing progressively from strong anteriorly to fine posteriorly; rugosity reaching occipital carina centrally, becoming very weak laterally, disappearing on temple. Gena polished; in dorsal view very weakly prominent; centrally and ventrally with sparse long pale hairs. Occipital carina ( Fig. 87 ) narrow, sharp, translucent; in dorsal view deeply emarginate into vertex, semicircular; in posterior view weakly convergent ventrally, ending far from hypostomal carina, at a distance almost as long as length of scape.

Mesosoma: Pronotum ( Figs 88, 89 ) apical margin weakly emarginate, narrowly reflexed upwards, sharp; colo long, centro­longitudinally weakly concave, generating a subtle, polished channel, its apex with a few transverse, weak, arched carinae; laterally, on each side, with 7 strong and strongly oblique carinae, converging towards semiannular; pronotal fold transverse, straight, narrow, very deep. Semiannular ( Figs 88, 89 ) transversally crossed by thick rugosity, which becomes fine along posterior margin, centro­laterally, and on lateral lobe. Femoral impression ( Fig. 88 ) distinct, moderately deep, transversally crossed by rugosity from semiannular; ventral area longitudinally rugulose. Prosternum apical flange strongly alutaceous, centrally weakly rugulose, basal half smooth, except marginally rugulose to rugose. Mesonotum from centraly strongly longitudinally rugose to laterally irregularly strongly rugose, median sulcus a weak straight groove, notaulus indistinct; axilla rugose as mesonotum; scutellum from laterally strongly longitudinally rugose to centrally areolate­rugose, except apico­centrally alutaceous (similar to Fig. 92 ). Mesopleuron with sparse long golden hairs; anteriorly, on pectus, with patch of fine white pilosity; laterally from dorsally coarsely to ventrally finely areolate­rugose, also densely microareolate inside areolae; centro­posteriorly with patch of fine white pilosity; pleural sulcus entirely strongly crenulate. Mesopseudosternum distinctly alutaceous; discrimen narrow, delimited by closely aligned foveolae. Crenulate sulcus ( Figs 90, 93 , in part) deep and wide, well isolated from propodeum. Propodeum ( Fig. 90 ) strongly areolate­rugose, flank and area behind pleuropropodeal fovea alutaceous and shiny; spiracular groove indistinct ( Fig. 90 ); spiracular carina faintly indicated by convergence of rugosity ( Figs 90, 93 ); parapetiolar depression indicated as largest areola near petiolar foramen, polished inside. Metapleuron ( Figs 90, 93 ) strongly areolate­rugose, finer anteriorly; anterior half dorsally with large patch of long, dense, parallel, ventrally decumbent white pilosity; ventral margin approximately straight, with very weak basal lobe. Pleuropropodeal and metapleural foveae deep; both foveae and interfoveolar area polished; pleural sulcus ( Fig. 93 ) fully, very regularly and strongly crenulate; anterior margin of interfoveolar area straight ( Fig. 93 ); postfoveolar area alutaceous. Hind coxa laterally densely microareolate, also with rugosity associated to its long, sparse hairs, particularly at base; dorsally transversely strigate; mesally flattened, densely and mostly transversely finely strigate and microareolate (as in Fig. 94 ). Fore wing vein M+Cu with 6 erect, equidistant setae grouped at apex, ending at point of conexion with vein 1M; vein (Rs+M)b about 7 times longer than centrally wide; vein 2­1A tubular only on its basal 0.18, otherwise absent, cell 2Cu mostly open posteriorly; veins 2Cua and 2Cub entirely nebulous.

Metasoma: Petiole basal end rugulose, with a few longitudinal wrinkles, changing to coarsely microfoveolate and then progressively to finely and delicately microareolate towards apex, including ventrally; dorso­apical margin polished; T3 (2 nd metasomal) finely but conspicuously longitudinally alutaceous; T4 very finely transversely strigulatealutaceous; T5–7 transversely microscopically strigulate; T8 coarsely alutaceous. In full lateral view, metasoma with fine matte texture due to its generalized fine and dense sculpture pattern.

Color. Entirely light colored ( Fig. 24 ), from brownish yellow (255,195,075) on head and pronotum to reddish brown (191,102,028) on mesopleuron. Apex of mandible, apex of coronal tubercles, longitudinal walls of crenulate sulcus and at articulation of hind coxa with metapleuron, dark brown. Hind leg reddish brown somewhat lighter than mesopleuron, compressed center of tibia and tarsi lightly colored, yellowish. Ovipositor reddish brown; ovipositor sheath with four major color sections ( Fig. 95 ) its basal 0.30 yellowish brown, next 0.36 dark brown, next 0.17 a subapical white band, followed by apical 0.17 dark brown, except the very apex (apical 0.04) black. Wing membrane light amber, veins brown.

Morphological variation in females. Range of biometric values in Table 1. All specimens very similar, but mesonotal rugosity, including scutellum, can be considerably coarser and more irregular than observed in the holotype, the median sulcus practically disappearing in this case.

MALE. Unknown.

Comments

This is the most typical Mexican stephanid, and one of the most characteristic species of the family. The pronotal shape and sculpture ( Figs 88, 89 ), particularly the narrow and transverse pronotal fold ( Fig. 88 ), the extremely coarse sculpture of the mesonotum, including the scutellum ( Fig. 92 ), and the four color areas of the ovipositor sheath ( Fig. 95 ) form an unique combination, making this species very easy to recognize. The following features can further aid its recognition: body entirely lightly colored ( Fig. 24 ), a long fore wing vein (Rs+M)b, and metapleuron dorso anteriorly with a white tuft of long, white, “combed” hairs ( Figs 90, 93 ). The four areas of color on the ovipositor valve also occurs in a similar way on a few specimens of M. texanus and M. celaenocephalus .

Distribution Mexico.

Material examined

Four females. Holotype ♀ ODAC “ Mexico, Jalisco, Est. Biol. Chamela , 17­X­1996, R. L. Westcott. OSUC22880 .” Left ovipositor sheath basally broken, but glued on place; otherwise complete, well preserved. Paratypes: ♀ EBCC “ Mexico, Jalisco, Chamela , fecha 16­VII­85, R. Ayala, s./. OSUC22877 .” ♀ EBCC “ Mexico, Jalisco, Est. Biol. Chamela , 8­ X­1991, R. L. Westcott. OSUC22879 .” ♀ EBCC “ Mexico, Jalisco, Est. Biología Chamela , 2­VII­1995, R. L. Westcott. OSUC22878 .”

Figures

FIGURES 9–16. Values of morphometric ratios for all examined female specimens of all species of Mexican Megischus. Species grouped in the Y­axis according to their order of appearance and morphological similarity in the key to species; key structure also indicated by the dendrogram applied to Y­axis of Figure 9. Legends for all graphs: an, M. anaxeus, sp. n.; az, M. arizonicus; bc, M. bicolor; cl, M. celaenocephalus, sp. n.; jc, M. jaliscoensis, sp. n.; ml, M. melanogladius, sp. n.; mx, M. mexicanus, sp. n.; ng, M. niger; pn, M. peninsularis, sp. n.; tx, M. texanus. For ratio abbreviations, see text.

FIGURES 23–25. Mexican representatives of Megischus Brullé. 23, M. celaenocephalus, sp. n., holotype ♀, dorsal view; 24, M. mexicanus sp. n., holotype ♀, habitus; 25, M. bicolor (Westwood), ♂, habitus. Illustrations not to scale.

FIGURES 87–95. Megischus mexicanus, sp. n., ♀. 87, head, dorsal, holotype; 88, pronotum + prosternum, left, holotype; 89, pronotum, dorsal; 90, propodeum + metapleuron, dorso­lateral left and slanted forward, holotype; 91, hind left tibia, posterior view, holotype; 92, mesonotum, including scutellum, also part of crenulate sulcus, paratype OSUC22877; 93, crenulate sulcus, interfoveolar area, propodeum + metapleuron, left, holotype; 94, hind left coxa, mesal, paratype OSUC22878; 95, ovipositor and sheaths, lateral, holotype. Illustrations not to scale.