Szelenyiopria pampeana (Loiácono) Loiacono, 2009

Loiácono, Marta S. & Margaría, Cecilia B., 2009, A note on Szelenyiopria pampeana (Loiácono) n. comb., parasitoid wasps (Hymenoptera: Diapriidae) attacking the fungus growing ant, Acromyrmex lobicornis Emery (Hymenoptera: Formicidae: Attini) in La Pampa, Argentina, Zootaxa 2105, pp. 63-65 : 63-65

Szelenyiopria pampeana (Loiácono) n. comb.

Gymnopria pampeana Loiácono in Loiácono et al. 2000: 10.

Remarks: Masner and García (2002) considered Gymnopria Loiácono as junior synonym of Szelenyiopria Fabritius by comparison with material type-species. Here, S. pampeana is considered as a new combination. Szelenyiopria pampeana (Loiácono) is similar to S. lucens (Loiácono) but differs by the coriaceous sculpture of head and mesosoma; scarcely pilosity of cheeks and anterior margin of prothorax; and wider first segment of antennal club.

Among the Diapriinae the Diapriini is the only tribe that includes truely symphilic species, some of them remarkably adapted morphologically to life with ants; these adaptations include extensive mimicry of the host ants which may include convergences in sculpture, pilosity, color behavior, and biology. Members of the genus Szelenyiopria share no specialized structures known from other myrmecophilic diapriini ; but there is evidence of setae with truncate apices which were considered by Masner and García (2002) to be specialized structures, possibly as outlets for chemical substances ( Fig. 2 a ).

Distribution: Argentina: La Pampa: Santa Rosa (36º62’ S, 34º 28’ W) and La Reforma (37º 55’, S 66º 23’W).

Biology: Szelenyopria pampeana is known as a koinobiont and gregarious endoparasitoids of larvae of late instars of Acromyrmex lobicornis Emery ( Loiácono et al. 2000) .

Parasitized larvae of A. lobicornis were easily recognized by the dark coloration of the cuticle caused by the developing wasps ( Fig. 1 b). All parasitized larvae belong to the reproductive forms of the ants, which can be recognized by the peculiar “ancoriforme” pilosity ( Fig. 2 b) (Covello de Zolessi and González 1974). In this study, we verified that S. pampeana attacks both nests of A. lobicornis in two locations of La Pampa province; all recovered wasps were females ( Fig. 1 e), and solitary parasitism was predominant. From the 33 ant larvae parasitized at La Reforma, 26 showed solitary parasitism ( Fig. 1 c) and five larvae were gregariously parasitized with up to three diapriids per larva ( Fig. 1 a, b). These results are not similar that those of Loiácono et al. 2000 for S. pampeana : the authors recovered in some cases, both sexes from a single host. Further, the number of wasps per larva ranged from 1 to 22; gregarism was predominant and the coexistence of two diapriid species of different genera was found ( S. pampeana and Trichopria formicans Loiácono ). Loiácono et al. (2000) colected 1560 wasps (adults and inmatures) from 430 parasitized larvae from three partial colonies of A. lobicornis , which shows how aggressive these wasps can be in attacking the ants. Fernández-Marín et al (2006) suggest that these minute wasps present excellent opportunities to explore the hypothesis that parasitoid wasps regulate host population density and community structure both through indirect and direct effects.

Figures

FIGURE 1. Ant larvae. a – b. showing immature states of diapriines, c. with adult diapriid emerging, d. after diapriid emergence. e. Szelenyiopria adult female (upper) and ant worker (lower).

FIGURE 2. a. Szelenyiopria pampeana female, mesosoma, detail of specialized setae with truncate apices. b. Formicid sexual larvae, detail of tegument with ancoriformes setae.