Goussia Labbe, 1986

Lovy, Jan & Friend, Sarah E., 2015, Intestinal coccidiosis of anadromous and landlocked alewives, Alosa pseudoharengus, caused by Goussia ameliae n. sp. and G. alosii n. sp. (Apicomplexa: Eimeriidae), International Journal for Parasitology: Parasites and Wildlife 4 (2), pp. 159-170 : 166-167

Genus: Goussia Labbe, 1986 .

Type host: Alosa pseudoharengus (Wilson, 1811) , common name, alewife, a species of river herring; parasite found in both anadromous and landlocked alewives, present in both young-of-the-year and adult fish.

Other host: unknown.

Type locality: Maurice River , New Jersey, USA in anadromous fish; Lake Hopatcong, New Jersey, USA in landlocked forms .

Other localities: unknown.

Type material: Histological sections, blocks, and photomicrographs are catalogued at the New Jersey Division of Fish and Wildlife Fish Pathology Laboratory , Oxford, NJ 07863, USA. Extracted DNA is stored at −80 ̊C in the New Jersey Department of Agriculture, Animal Health Diagnostic Laboratory. The small subunit 18S ribosomal DNA sequence has been deposited in GenBank under accession number KP411007 .

Parasite description: In fresh preparations, unsporulated oocysts were rounded to ovoid in shape ( Figs 1A and 3A ). Sporulated oocysts with smooth, thin, irregular oocyst wall. Oocyst residuum, micropyle and polar granules absent. Oocysts contain 4 ellipsoidal sporocysts with abundant sporocyst residuum; steida body not observed in sporocysts using light microscopy. Two elongated sporozoites closely opposed to each other within each sporocyst and partially covered with sporocyst residuum. Dimensions of sporocysts varied between anadromous and landlocked forms after in vitro sporulation (see Table 1), possibly due to incomplete sporulation or differing sporulation dynamics of anadromous form. Line drawings of sporulated oocysts are shown from anadromous ( Fig. 5A ) and landlocked ( Fig. 5B ) fish. Measurements summarized in Table 1.

In histology, meronts containing 10–15 elongated merozoites (n = 9) arranged radially in landlocked alewives and 6–7 merozoites (n = 4, Fig. 3D ) in anadromous forms ( Fig. 1E ). Early developmental stages were small (about 2 μm) spherical to slightly elongated, basophilic staining structures in brush border of intestinal epithelium. Macro and microgamonts were spherical to slightly ovoid shaped and occurred in an epicellular position in intestinal epithelium. Unsporulated oocysts were slightly ovoid or spherical and occurred in an epicellular position or sloughed in the intestinal lumen. Sporulation of oocysts occurred in lumen of intestinal tract of anadromous fish, while sporulation was rare in intestine of landlocked forms. Exogenous sporulation occurred in the landlocked forms.

Infection site: Anterior intestine, predominantly pyloric cecum.

Prevalence: In anadromous alewives, prevalence was 76% and 86% in YOY and adult spawning fish, respectively. In landlocked forms, prevalence was 92% and 34% in YOY and adult fish, respectively (see Table 2).

Pathology: Heavy parasite infection on surface of intestinal epithelium covering a large percentage of the intestinal epithelium. Infection was associated with focal necrosis and sloughing of intestinal epithelium. Mucoid casts containing parasite stages were observed in heavily infected individuals.

Etymology: The species was named after Amelia, the senior author’s niece whose birth coincided with the completion of the present study.

Figures

Fig. 1. Goussia ameliae from anadromous alewives, bar = 10 μm. (A–C) Wet mounts of fresh coccidia preparations with (A) unsporulated oocysts, (B) oocysts in the process of sporulation, and (C) sporulated oocysts containing four sporocysts. (D–H) Histology documenting various stages of coccidia infection in the pyloric cecum, stained with H&E. (D) Intestinal epithelium with a severe infection of coccidia stages including gamonts and unsporulated oocysts covering the intestinal epithelium; (E) meront containing merozoites (arrow) attached to the microvillar surface of intestinal epithelial cells; (F) gamogony with macrogamonts (arrow) and microgametocytes (arrowhead) with an epicellular position; (G) unsporulated oocysts with an epicellular position (notice below, the focal necrosis to the intestinal epithelium); (H) a focal erosion in the intestinal epithelium with unsporulated and sporulated (arrow) oocysts released into the lumen.

Fig. 3. Goussia ameliae from landlocked alewives, bar = 10 μm. (A–C) Wet mounts of fresh coccidia preparations with (A) unsporulated oocysts and (B,C) sporulated oocysts containing four elongated sporocysts. (D–H) Histology documenting the development of the coccidian in the pyloric cecum, stained with H&E.(D) Meronts containing merozoites within the brush border on the surface of the intestinal epithelium; (E) early developmental stages (arrowheads) embedded within the brush border; (F) macrogamonts with an epicellular position on the intestinal epithelium; (G) microgametocytes (arrowhead) and unsporulated oocysts (arrow) which have sloughed from the epithelial surface; (H) severe coccidiosis with various developmental stages occupying most of the surface of the intestinal epithelium.

Fig. 5. Line drawings of sporulated oocysts of Goussia ameliae from (A) anadromous and (B) landlocked alewives and (C) G. alosii sampled from landlocked alewives, bar = 5 μm.