<i>Mattesia grandis</i> n. sp., a Sporozoan Pathogen of the Boll Weevil, <i>Anthonomus grandis</i> Boheman*

Abstract

SYNOPSIS. Laboratory cultures of the boll weevil, Anthonomus grandis Boheman, became infected with Mattesia grandis n. sp. (Neogregarinida, Ophryocystidae). The ensuing epizootic resulted in destruction of the weevil colony. Infection occurred per os in larval and adult weevils. Sporozoites penetrate the intestinal wall and infect adipose tissue cells. Micronuclear schizogony with production of merozoites is the primary method of multiplication and spread to new foci. Micronuclear schizonts may grow as large as 30 μ in size and produce up to 200 or so merozoites, which may be 20 μ long and 1–2.5 μ wide and are motile. Macronuclear schizonts are formed from these 1st schizogony merozoites, and can become 20–30 μ in size, producing up to 80 or so macronuclear merozoites. These can be 15 μ long but 2–3 μ wide with limited motility. Second schizogony merozoites form gamonts, which pair, forming gametocysts. Nuclear division occurs, resulting in 4 equal sized nuclei and 2 pairs of residual nuclei. Four gametes are formed by cytoplasmic constriction around the nuclei. The gametes rapidly pair to form 2 zygotes in the gametocyst, resulting in 2 spores. Nuclear pairing in 1 of the 2 zygotes often lags slightly behind. Abnormal development of zygotes was rare, but could result in 1 spore with 3 poles and a normal spore, or with only 1 spore developing. Near maturity gametocysts are about 12.5 μ long and 14.0 μ wide, with the gametocyst wall tightly stretched over the poles of the spores. Spores often are slightly flattened on the adjacent side in the gametocyst but frequently attained evenly curved walls on all sides after release. The spores are octozoic, with sporozoite development occurring after release from the gametocyst. Spores measured 7.1 μ X 11.8 μ. Characters are given to separate M. grandis from other species of Mattesia.