Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 68. (Budapest 1976)

Huddleston, T.: A revision of Elasmosoma Ruthe (Hymenoptera, Braconidae) with two new species from Mongolia

ANNALES HISTO RICO-NATU KALES MUSEI NATIONALIS HUNGARICI Tomus 68. Budapest 1976. A Revision of Elasmosonia Ruthe (Hymenoptera, Braconidae) with Two New Species from Mongolia* by T. HUDDLESTON, London Abstract — Three new species of Elasmosoma are described — two from Mongolia, the third from Europe. A lectotype is designated for E. luxemburgense WASMANN and there is a key to nine of the species of Elasmosoma. With 15 figures. The subfamily Neoneurinae consists of the genera Neoneurus and Elasmosoma both of which are found in association with ants. The two genera are closely similar morphologically and the few recorded observations upon their host selecting and ovipositing behaviour show that they probably also have closely similar life histories. From studies of their larval and adult morphology and of their biology it is now generally accepted (CAPEK 1970) that Neoneurinae are more closely related to Euphorinae than to Microgasterinae where they have frequently been put in the past. Biology — The evidence that Neoneurus and Elasmosoma are parasitic upon ants is chiefly circumstantial. It is that the parasites are frequently found in association with ants, in which they take an active interest of which the ants appear to be aware. PIERRE (1893) and DONISTHORPE (1927) claim to have observed Elasmosoma ovipositing in the abdomen of adult worker ants, and DONISTHORPE, also claims to have reared Elasmosoma from observation nests. DONISTHORPE 'S statements, however, almost certainly apply to Neoneurus following MORLEY'S (1914) misidentification of Neoneurus kalidaii MARSHALL as Elasmosoma berolinense RUTHE, a nomenclatorial confusion which persisted until cleared up by NIXON" (1934). With few exceptions Elasmosoma species have been found in association with formicine ants ; these ants exude formic acid which is a powerful attractant for predatory ant species (B. BOLTON, personal communication) and it seems likely that this exudate could serve also as a kairomonal stimulant to host-seeking by Elasmosoma. No one has yet succeeded in rearing Elasmosoma in circumstances which show unequivocally that the parasite develops in adult worker ants ; their habit of approaching ants however, seems strongly to suggest that this is so. PIERRE (1893) wrote that the parasite always approaches the ant from behind, probably a necessary precaution since he also states that the ants appear to be aware of the presence of the parasite. If the orientation of the ant be propitious — if it still has its back turned — the Elasmosoma then makes a brief contact with the abdomen of the ant during which time PIERRE supposed that oviposition occurred. DR. R. D. HARKNESS recently made similar observations when he took E. platamonense in Greece. The parasite approached from behind the ant and remained in contact with the tip of the abdomen for less than one second (personal communication). The form of the ovipositor in Elasmosoma — strongly curved, almost hookshaped, and forward-pointing when exserted — gives support to the supposition that eggs are laid as described, into the gaster of adult workers. Parasites of other groups (Pygostolus, for instance, a parasite of weevils) which are known to lay their eggs in the abdomen of the host adult usually by inserting it through the anus have an ovipositor of a similar shape and disposition. It is significant that HARKNESS "•Ergebnisse der zoologischen Forschungen von DE. Z. KASZAB in der Mongolei, Nr. 365. Ann. Hist.-nat. Mus. Nat. Hung., 1976, 68.