Orthosomella lambdinae n. sp. (Microsporida: Unikaryonidae) from the Spring Hemlock Looper, Lambdina athasaria (Lepidoptera: Geometridae)

Author： Andreadis T.G. Maier C.T. Lemmon C.R.

Publisher： Academic Press

ISSN： 0022-2011

Source： Journal of Invertebrate Pathology, Vol.67, Iss.2, 1996-03, pp. : 169-177

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Abstract

A new species of microsporidia, Orthosomella lambdinae n. sp. (Microsporida: Unikaryonidae), is described from larvae of the spring hemlock looper, Lambdina athasaria (Lepidoptera: Geometridae). The principal site of infection is the midgut epithelium. The microsporidium is free within the hyaloplasm of the host cell and has unpaired nuclei in all stages of development. Schizonts are rounded to irregular in shape with a variable number of nuclei (2-29, median = 6). They are limited by a simple plasmalemma and divide by plasmotomy. Sporogonial plasmodia are elongate and sausage-shaped with a variable number (2-18, median = 6) of linearly arranged nuclei. They are surrounded by an electron-dense surface coat and give rise to moniliform chains of uninucleated sporoblasts with a corresponding number of nuclei. Sporoblasts concurrently undergo sporogenesis prior to cytoplasmic cleavage into free spores. Mature spores are uninucleate and oblong to slightly reniform. They measure 2.8 x 1.5 mum (live) and have 7-8 turns of the polar filament. The natural prevalence of O. lambdinae in larval populations of L. athasaria was found to range from 2.0 to 18.4% (6.8% overall).