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Table 4 Key to Giovannolaia species

From: Keys to the avian malaria parasites

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Features and species

1 (16)

Elongate meronts, which grow laterally to nuclei of infected erythrocytes (Figs. 2c–e; 3w–y), predominate

2 (3)

Cytoplasm of gametocytes (especially macrogametocytes) is highly vacuolated (Fig. 4o). Large (> 1.5 µm in diameter) vacuoles are present in some macrogametocytes

………………………………………………. P. fallax [1, 8, 92]

3 (2)

Cytoplasm of gametocytes is not highly vacuolated; if vacuoles are present in macrogametocytes, they are few and of small size (< 1 µm in diameter) (Fig. 4p–s)

4 (5)

Pigment granules in the majority of erythrocytic meronts are aggregated into large (> 1.5 µm in length) clumps, which usually locate at one end of elongate meronts (Fig. 5f)

………………………………………………. P. anasum [1, 8, 93]

5 (4)

Pigment granules in the majority of erythrocytic meronts are not aggregated into large (> 1.5 µm in length) clumps, which usually locate at one end of elongate meronts (Fig. 5f). Location of pigment granules in erythrocytic meronts is markedly variable

6 (7)

Nuclei tend to lean to one end in the majority of growing erythrocytic meronts (Fig. 5d)

………………………………………………. P. leanucleus [8, 94]

7 (6)

Nuclei do not tend to lean to one end in the majority of growing erythrocytic meronts (Fig. 5d). Position of nuclei in developing meronts is markedly variable (Fig. 3u, x)

8 (11)

Average number of merozoites in mature meronts is < 12

9 (10)

Fully grown erythrocytic meronts and gametocytes are thin slender cells, they do not displace the nuclei of infected erythrocytes and usually do not adhere to the nuclei (Fig. 5e)

………………………………………………. P. gundersi [1, 8, 95]

10 (9)

Fully grown erythrocytic meronts (Fig. 3w) and gametocytes (Fig. 5k) are broad cells, which width is equal to the width of erythrocyte nuclei or is greater; both mature meronts and gametocytes displace the nuclei of infected erythrocytes laterally and often adhere to the nuclei (Figs. 3w; 5k)

………………………………………………. P. octamerium [8, 96]

11 (8)

Average number of merozoites in mature meronts is ≥ 12

12 (15)

Gametocytes and meronts grow around nuclei of erythrocytes (Figs. 2c, d; 4r, s). Fully grown erythrocytic meronts and gametocytes usually only slightly (if at all) influence infected erythrocytes and do not displace or only slightly displace nuclei of erythrocytes laterally (Figs. 2d, e; 4s). Infected erythrocytes usually do not become rounded (Fig. 5x)

13 (14)

Fully-grown erythrocytic meronts (Fig. 2d, e) and gametocytes (Fig. 4s) markedly (often nearly completely or completely) encircle nuclei of infected erythrocytes; completely circumnuclear mature meronts and gametocytes frequently develop, but their occurrence depends of stage of parasitemia, so they might be not always seen in blood films

………………………………………………. P. circumflexum [1, 8, 97] , P. homocircumflexum [35]a

14 (13)

Fully grown erythrocytic meronts never assume circumnuclear form (Fig. 3w, y). Gametocytes nearly completely (Fig. 4r) or completely (Fig. 4s) encircle nuclei of infected erythrocytes; completely circumnuclear mature gametocytes develop, but usually are rare. Advanced trophozoites and young meronts often possess large (> 1 µm in diameter) vacuoles (Fig. 5j)

………………………………………………. P. lophurae [1, 8, 98]

15 (12)

Gametocytes and meronts start to grow around nuclei of erythrocytes

However, fully grown meronts markedly displace nuclei of erythrocytes and assume various irregular forms; they often roundish or close to roundish in shape (Fig. 5w), markedly displace the nuclei of infected erythrocytes and can occupy all available cytoplasmic space in the erythrocytes (Fig. 5w). Fully grown gametocytes markedly deform infected erythrocytes, which become rounded (Fig. 5x, y)

………………………………………………. P. gabaldoni [8, 99]

16 (1)

Elongate erythrocytic meronts, which grow laterally to nuclei of infected erythrocytes (Figs. 2c–e; 3w–y), are absent or appear only occasionally; they never predominate. The majority of fully grown meronts are of roundish, oval or irregular form; they do not take or take only occasionally the lateral position to nuclei of erythrocytes (Fig. 5q–s)

17 (24)

Large (> 1.5 µm in diameter) vacuoles (Fig. 5g) absent from gametocytes. If small vacuoles are present in gametocytes, pigment granules do not gather around vacuoles

18 (25)

Fully grown gametocytes do not tend to lie obliquely in infected erythrocytes (Fig. 5i, o), and they do not displace the nuclei towards one pole of the erythrocytes

19 (26)

Growing erythrocytic meronts do not produce long (> 2 µm in length) tail-like or finger-like outgrowths (Fig. 5c)

20 (21)

Erythrocytic meronts take a polar or subpolar position in infected erythrocytes, and their influence on infected erythrocytes is usually not pronounced (Fig. 3r)

………………………………………………. P. polare [1, 8, 100]

21 (20)

Erythrocytic meronts can be seen anywhere in infected erythrocytes including a lateral, subpolar and polar position. If meronts take a polar or subpolar position in the erythrocytes, they markedly influence the host cells causing their deformation and (or) displacement of their nuclei

22 (23)

Maximum number of merozoites in mature meronts > 10. Size of pigment granules in macro- and microgametocytes is clearly different

………………………………………………. P. pinottii [1, 8, 101]

23 (22)

Maximum number of merozoites in mature meronts < 10. Size of pigment granules in macro- and microgametocytes is similar

………………………………………………. P. garnhami [1, 8, 102]

24 (17)

Large (> 1.5 µm in diameter) vacuoles (Fig. 5g) develop in many macrogametocytes. Pigment granules often gather around these vacuoles

………………………………………………. P. formosanum [1, 8, 103]

25 (18)

Fully grown gametocytes tend to lie obliquely in infected erythrocytes, and they displace the nuclei towards one pole of the erythrocytes (Fig. 5o)

………………………………………………. P. durae [1, 8, 104]

26 (19)

Growing erythrocytic meronts often produce long (> 2 µm in length) tail-like or finger-like outgrowths (Fig. 5c)

27 (28)

Nuclei in mature erythrocytic meronts are usually arranged as fans (Fig. 3v), rosettes (Fig. 5r), or more or less pronounced rows (Fig. 3w). Infected erythrocytes with segmented mature meronts are often rounded (Fig. 5r). Fully grown gametocytes do not fill erythrocytes up to their poles (Fig. 4h)

………………………………………………. P. pedioecetae [1, 8, 105, 106]

28 (27)

Nuclei in mature erythrocytic meronts are usually located randomly (Fig. 3q) and they only occasionally can be arranged as rosettes. Infected erythrocytes with segmented mature meronts are not rounded (Fig. 3w). Fully grown gametocytes fill erythrocytes up to their poles (Fig. 5k)

………………………………………………. P. hegneri [8, 93]

  1. aBased on available information, P. circumflexum and P. homocircumflexum are cryptic species, which cannot be distinguished using morphological features of their blood stages [35]. Cytochrome b sequences can be used to distinguish these infections (see Table 7)