Table 2 Characteristics of the four microsporidian genera contained within the family Enterocytozoonidae

Host

Caligid copepod, Lepeophtheirus salmonis

Mammals and birds^a and penaeid shrimp^b

Fish (salmonid, freshwater, and marine)

Marine decapod crabs

Host cell-type infected

Desmocytes in the glycocalyx bordering haemocoelic cavities

Enterocytes ^a

Tubule epithelial cells of the hepatopancreas ^b

Haemopoietic cells and blood leukocytes ^c

Intestinal epithelial cells^d

Hepatopancreas epithelial cells

Mature spore shape and size

Round to sub-spherical

2.34 × 1.83 (± 0.01) fresh

Spherical to ovoid, 1.5 × 0.8 ^a (fixed)

Oval 1.1 × 0.7 (fresh/percoll-purified)

ovoid to pyriform, 2 × 1 (fixed) ^c

ellipsoidal 1.6 × 0.8 (ultrathin sections)^d

1.3 (± 0.02) × 0.7 (± 0.01) (fixed)

Number of turns and type of polar filament

Isofilar, 5-8 turns (usually a double layer)

4-7 turns (double layer)^a

5-6 turns (double layer)^b

8-12 turns (single or double layer)^c

4-5 turns (double layer) ^d

4-5 turns (double layer)

Spore production

Polysporous, without interfacial envelop

Polysporous, without interfacial envelop

Polysporous, without interfacial envelop

Polysporous, without interfacial envelop

Location in host cell

Cytoplasm

Cytoplasm

Nucleoplasm (intranuclear)

Nucleoplasm (intranuclear)

Earliest stage observed

Diplokaryotic meront

Uninucleate meront

Uninucleate meront

Binucleate meront

Plasmodium/syncitium stage

Merogonial plasmodium divides via plasmotomy.

No sporogonial plasmodium present.

Merogonial plasmodium transforms to sporogonial plasmodium without prior division.

Merogonial plasmodium transforms to sporogonial plasmodium without prior division.

Merogonial plasmodium transforms to sporogonial plasmodium without prior division.

Key references

Present study, [21, 23]

^a[29, 31, 33, 41]

^b[14]

^c[32, 33]

^d[34]

[3, 4]