Myzinum navajo Krombein

Myzinum navajo (Krombein)

Fig. 20, Map 6

Myzine navajo Krombein 1938:272. Holotype female; USA: Arizona, Florence (PHILADELPHIA).

Male.―Body length 15–20 mm. Head: hypostome forming right angle in profile; frons punctures contiguous; ocellocular distance as long as interocellar distance; flagellomere I length 1.6x breadth; flagellomere IX length twice breadth. Thorax: mesopleuron without omaulus, punctures 0.5 PD apart; propodeum transversely rugosopunctate; fore, mid and hindcoxae unmodified. Metasoma: tergum VII flat, weakly longitudinally striate apicomedially. Genital capsule (Fig. 20): paramere ventral lobe 5x as long as broad, 7–8 spines along apical one-third, dorsal lobe marginal setae fewer than five, more than two-thirds as long as volsella; volsella rounded apically, ovoid in cross-section, setose apically, half as long as paramere ventral lobe; aedeagus apical bulb twice as broad as shaft below, with large basal lamella. Color: black, with yellow markings; clypeus yellow; inner eye margin with yellow band along inner margin; antennal lobe with yellow spot; pronotum with broad anterior and posterior yellow bands; mesopleuron with large anterior and smaller posterior yellow spots; scutum, scutellum and metanotum with medial yellow spots; tegula yellow; coxae, femora and tibiae with yellow band or spot; tarsi yellow; propodeum with large yellow lateral spot; metasomal terga I–VI with transverse posterior yellow band, sterna II–VI with elongate posterolateral yellow spot; wing membrane lightly brown-tinted. Vestiture: silvery.

Female.―Body length 15–19 mm. Head: frons punctures coarse, contiguous near antennal lobes, becoming nearly impunctate around midocellus and on vertex; ocellocular distance 1.8x interocellar distance; hypostomal angle forming right angle in lateral view. Thorax: pronotum dorsal surface without tiny interpunctures between punctures; forebasitarsis with eight rake spines; propodeum laterally coarsely and evenly cross-ridged, contiguous with coarse parallel ridging radiating outward from petiolar socket on posterior surface. Color: black, with yellow markings; reddish brown on legs, antenna and mandible; yellow band along inner eye margin; pronotal disk with large medial or two sublateral yellow spots; mesopleuron with anterior and sometimes posterior yellow spots; scutum with medial and lateral yellow spots; scutellum may have medial yellow spot; metanotum yellow medially; legs reddish brown; metasomal terga I–V with large lateral yellow spot; forewing brown-tinted, darkest along costal margin. Vestiture: pale yellowish to silvery.

Distribution (Map 6).― USA: Arizona: Cochise, Pima, Pinal, Santa Cruz Counties; New Mexico: Hidalgo Co.; Texas: Brewster Co.; MEXICO: Chihuahua, Colima, Guerrero, Michoacán, Morelos, Oaxaca, Sinaloa, Sonora, Veracruz, Zacatecas; EL SALVADOR; COSTA RICA: Guanacaste Prov.; 130 females and 165 males were studied.

Discussion.―This is another of the large-bodied Myzinum species. It is superficially similar to carolinianum. Females have distinctive, coarse ridging on the propodeum. Males have an unusual, apically enlarged aedeagus (Fig. 21). The apex of the aedeagus is so large that it can often be seen protruding between the apical tergum and sternum if they are parted slightly. In addition, male navajo have spines extending along the apical two-thirds of the inner margin of the ventral lobe of the paramere. Otherwise, male navajo look very much like male carolinianum. However, navajo occurs only from southern Arizona to southwestern Texas, south into El Salvador, while carolinianum occurs in the southeastern U.S.