Ariasina Heydon

Heydon, Steven L., 2014, Review of south temperate New World Coelocybinae (Hymenoptera: Pteromalidae), Zootaxa 3754 (4), pp. 420-434 : 425

Ariasina Heydon n. gen.

Type species. Ariasina adusta Heydon n. sp.

Description. Female. Body color non-metallic, mottled dark brown or almost black depending on species. Head with clypeus small and subcircular, anterior margin convex. Antenna with toruli located just below lower ocular line; scape relatively short, clearly not reaching to median ocellus; flagellum with basal two segments quadrate or greatly elongate but without MPP sensilla; funicular segments with single row of MPP sensilla, although number may be much reduced on basal few funicular segments. Mesosoma dorsoventrally compressed; pronotum elongate and more or less smoothly arched in profile; mesoscutum lacking conspicuous bristles, with notauli shallow, completely sculptured, lacking smooth parallel-sided groove; scutellum with frenum distinctly separated, more smoothly sculptured than remainder of scutellum, completely pilose anterior to frenal sulcus, and with two pairs of dark bristles posterolaterally; propodeum with complete median carina, weakly sculptured. Legs with hind coxal sculpture consisting of deep elongate pits in a whorled pattern similar to that seen in a fingerprint; hind tibia with two spurs. Fore wing almost completely hirsute, without any maculation. Petiole transverse. Gaster with basal tergite smooth and undifferentiated anteriorly, differentiated from succeeding segments.

Remarks. Ariasina can be distinguished from Lanthanomyia and Ambogaster , the other two genera of Coelocybinae in this region, by the possession of the following characters: mesosoma flattened, the pronotum elongated with neck and collar not distinctly separated ( Figs 7, 8 ), notauli weak posteriorly and completely sculptured, and T1 smooth or weakly sculptured ( Fig. 7 ). Its hind coxa sculpturing, whirled like in a fingerprint, is shared with Lanthanomyia , whereas Ambogaster has more normal sculpturing of the hind coxa for the family, with reticulations extending along the length of the coxa. Lanthanomyia and Ambogaster have the mesosoma not flattened, and the pronotum short with a distinctly convex surface between the horizontal collar and the more vertical neck. These latter genera also have the notauli reaching the hind margin of the mesoscutum as a smooth groove ( Figs 16, 21 ) and the first gastral tergite distinctly sculptured.

Most of the known coelocybine genera are found in Australia, and a complete phylogenetic analysis of the subfamily is beyond the scope of this paper. Character polarity in this subfamily is poorly understood. For example, the New World genera have antennae with the first and second flagellar segments quadrate and the funicular segments quadrate or longer than wide, while almost all of the Australian genera have antennae with the basal flagellar segments anelliform and the funicular segments mostly wider than long. Some Australian genera have complete notauli and some have shallow notauli like those in Ariasina . Until the relatives of the Coelocybinae are identified, it is not possible to say if long antennal segments or shallow notauli are primitive or advanced. The flattened mesosoma, the elongate pronotum, and the shallow notauli make the appearance of Ariasina species distinct from those of Lanthanomyia . One cannot defend the generic classification of the Pteromalidae as being phylogenetically robust, but any one of these characters found in other pteromalid species would be enough to define a new genus. The three in combination make Ariasina a well-defined and probably phylogenetically unified unit. It is entirely possible that Lanthanomyia will be found to be a collection of phylogenetically primitive species.

All known specimens of Ariasina are from Chile, but the genus should also be present in far southwestern Argentina. Ariasina is highly unusual in Pteromalidae in having the apical anellus (A2) longer than the first funicular segment in both known species.

Biology. All Ariasina specimens for which there is any biological information were collected off Nothofagus obliqua by canopy fogging. It is likely that these wasps are involved with galls on Nothofagus trees.

Etymology. This genus is named for Elizabeth Arias whose collecting efforts have made the Chilean insect fauna among the best known in all of South America. The gender is feminine.

Figures

FIGURES 5 – 8. Ambogaster and Ariasina spp. 5. Ambogaster wibawae Heydon, ♀ body. 6. Ambogaster wibawae Heydon, ♀ propodeum and first gastral tergite. 7. Ariasina adusta n. sp., ♀ PT body. 8. Ariasina gigas n. sp., ♀ PT body.

FIGURES 16 – 21. Lanthanomyia spp. 16. Lanthanomyia bockleri n. sp., ♀ PT body. 17. Lanthanomyia bouceki Heydon, light form, ♀ body. 18. Lanthanomyia bouceki Heydon, dark form, ♀ body. 19. Lanthanomyia pardos n. sp., ♀ PT body. 20. Lanthanomyia tigrita Heydon, ♀ PT body. 21. Lanthanomyia tigrita Heydon, ♀ PT propodeum and first gastral tergite.