Diachasmimorpha mexicana Cameron, 1887

The body of the D. mexicana holotype is remarkably smooth relative to that of other species in the Diachasmimorpha mexicana species group. The precoxal sulcus, for example, is very weakly crenulate, the propodeum is very weakly sculptured in general but completely smooth and polished anterior-laterally, and T1 is unsculptured except for the very short dorsal carinae. Sculpture is variable to some extent in other species of this species group, and thus it would be useful to obtain additional specimens of the true D. mexicana to determine the extent of sculptural variation in this species and ascertain whether reduction in sculpture is a useful diagnostic feature.

In his redescription of this species, Fischer (1967b) noted that the specimen labeled as the type in BMNH is a male, but Cameron (1887) indicated in his original description that he was describing a female. The excellent figure in Cameron (1887) matches the type specimen, providing additional evidence of Cameron’s error (either misinterpretation of the male genitalia as an ovipositor or, more likely given the general quality of Cameron’s early work, a typographical error).

See additional remarks under Diachasmimorpha hildagensis (Fischer).

Taxonomic History / Nomenclature
This species was originally described as Opius mexicanus by Cameron (1887). It was later placed in Desmiostoma by Fischer (1967, 1977) and ultimately transferred to Diachasmimorpha by Wharton (1997).
Diagnosis and Relationships
Holotype male. Eye in dorsal view shorter than temple, temples weakly expanded beyond eyes; eye in lateral view 0.95 x length of temple. Frons unsculptured along midline between antenna and median ocellus. Clypeus 3.4 x wider than high. Occipital carina distinct near base of mandible, short, not extending dorsally to ventral margin of eye. Antenna broken. Pronope deep, large, interrupting posterior crenulate groove middorsally. Notauli deep anteriorly, reaching margin of mesoscutum anteriorly, apparently extending about half distance from anterior-lateral margin to elongate midpit but pin obliterates midpit and surrounding area of mesonotum. Precoxal sulcus very weakly crenulate, nearly smooth, short, not extending close to anterior margin of mesopleuron. Propodeum largely smooth, with rugulose sculpture largely confined to midline, especially around apex, and along border of metapleuron. Fore wing 2RS 0.8 × 3RSa; m-cu distinctly postfurcal. T1 with dorsal carinae widely separated, short, barely extending to level of spiracle, T1 otherwise unsculptured. Head, meso- and metasoma orange, tegula black; legs black as in holotype of D. hildagensis. Body length about 4.0 mm. This species has a much smaller eye (Figs 2, 3) than the similarly-colored D. sanguinea (Fig. 6) and is also less heavily sculptured. Females are unknown.

This species is very similar to Diachasmimorpha sanguinea (Ashmead). Careful comparison of the two suggests that Diachasmimorpha sanguinea is a more heavily sculptured species with a distinctly larger eye. Diachasmimorpha sanguinea has frequently been reared as a parasitoid of Zonosemata infesting Solanum in the southern U.S., whereas the name mexicana has previously been applied to the species attacking Rhagoletis in Mexico. After comparison of the holotype of mexicana in 2011 (Figs 1-5), I now conclude that the parasitoid of Rhagoletis in Mexico is not Diachasmimorpha mexicana due to differences in color and size of the eye.

1. Diachasmimorpha mexicana holotyp...
2. Diachasmimorpha mexicana...
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5. Diachasmimorpha mexicana holoty...
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Originally described from Mexico, most likely from Mexico City.

Type locality: Mexico, D. F., Chapultepec.

No referenced distribution records have been added to the database for this OTU.
Biology / Hosts
This species was described from a single male specimen, without any associated biological information.

Diachasmimorpha mexicana has been recorded as a parasitoid of Rhagoletis in Mexico (Rull et al. 2009), based on initial studies by Wharton. More detailed recent work indicates that the species attacking Rhagoletis is the newly described Diachasmimorpha martinalujai Wharton, and as a consequence, there are no confirmed records of hosts for the true Diachasmimorpha mexicana.

Biology and Behavior