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Research Article

Table 1

Morphological differences between five very similar gregarines of acridians reported in the literature. This table is based on individual descriptions provided by the authors of [7, 21, 22, 24, 30]; see also [17]. D, diameter; L, length; W, width; TL, total length.

Gregarine Gregarina acridiorum (Léger, 1893) Labbé, 1899 [24] [21] Gregarina garnhami Canning, 1956 [7] Gregarina rigida (Hall, 1907) Ellis, 1913 [17] Gregarina ronderosi, Lange & Wittenstein, 2002 [22] Gregarina caledia, Ninham, 1995 [30]
Hosts Caelifera: Acrididae, Tetrigidae; Ensifera: Tettigoniidae Caelifera: Acrididae Caelifera: Acrididae; Ensifera: Tettigoniidae Caelifera: Acrididae Caelifera: Acrididae
Infected sites in hosts Midgut Early stages in gastric ceca and occasionally in the midgut; gamonts in the midgut Early stages in gastric ceca, near the anterior end of the midgut Trophozoites, solitary or associated gamonts in gastric ceca and gut; gametocysts in the hindgut Trophozoites, solitary or associated gamonts in gastric ceca and midgut; gametocysts in the hindgut
Trophozoites – gamonts
Gamonts Gamonts: cylindrical, ovoid in older forms, endocyte yellow orange.
  • L: ~ 400 μm, W: 160 μm

Gamonts: rather stout bodied in older forms, endocytes are pale yellow.
  • L: 250–554 μm

Gamonts: rather stout bodied, endocytes are brownish orange.
  • L: 250–750 μm

  • W: 130–210 μm

Trophozoite (epimerite): L: 10.4–275 μm, more slender than gamonts; Gamonts: rather stout bodied, endocytes are pale yellow.
  • L: 80–348 μm

Gamonts: pale-yellow, ovoid then cylindrical
  • L: 180–264 μm

  • W: 60–70 μm

  • Mean: 222 μm × 65 μm

Association Length TL: up to 1000 μm TL: 500–1110 μm TL: up to 1425 μm (average: 550 μm). Protomerite smaller in the satellite than in the primite TL: 160–700 μm (average: 425 μm). Primites and satellites are similar in size and shape TL: 515 μm. Primites and satellites are similar in size. Also seen: primite with 2 small satellites
Epimerite Small, spherical with a short stalk. Small, globular with a short stalk. Small spherical hyaline knob. Conical when attached, globular and smaller in free trophozoites Globular
Protomerite Sub-globular in primites, depressed at the anterior end in satellites. Conical in young stages, subspherical in older stages, widest at the septum, tapering towards the anterior end, flattened in satellite. Somewhat flattened, 3 times wider than long, generally less constriction at septum more or less indistinct. Sub-globular in primites, depressed at anterior end in satellites, less flattened than in G. garnhami Rounded anterior end
Deutomerite Cylindrical, rounded posterior end Cylindrical or rounded, with sharply pointed posterior end Cylindrical or barrel-shaped, little wider than protomerite, broadly rounded end or flattened “cornered” extremity Cylindrical, rounded posterior end, wider than protomerite, barrel-shaped in older forms Cylindrical, in small gamonts, wider than in protomorites and rounded in older forms
Gametocysts – oocysts
Gametocysts D: 500 μm, thick ectocyst D: 114–470 μm (exclusive of the ectocyst) D: 300 μm in average. Yellow orange color. Thick ectocyst D: 96–376 μm. Thick ectocyst D: 228–312 μm (mean 270 μm). Yellow orange color. Ectocyst (24–100 μm thick)
Basal discs Yellow orange Yellow orange Not mentioned Orange Orange
Sporoducts 12–15, with a swollen basal part, L > 1/2 cyst diameter 8, L: 1/3 cyst diameter (without ectocyst) 10 or more, short 12–15, L: up to 60 μm 5 to more than 10
Oocysts (sporocysts) Dolioform*, double wall Dolioform*, thick wall Barrel-shaped* Dolioform* or Barrel-shaped* Barrel-shaped*
7.6 μm × 3.3 μm 6.5–7 μm × 4 μm 8 μm × 5 μm 5 μm × 3.2 μm 12 μm × 6 μm

Depending on the authors, the terms “dolioform” and/or “barrel-shaped” were used to describe the shape of oocysts. Note also that oocysts were called sporocysts in all these historical descriptions.