Table 5 Key to the Novyella species

1 (19)

Maximum number of merozoites in erythrocytic meronts > 4

2 (41)

Maturing erythrocytic meronts, which displace host-cell nuclei, assume a fan-like shape and possess elongate nuclei (Fig. 3v), are absent

3 (26)

Erythrocytic meronts, which lie free in the cytoplasm of host cell and do not touch the nuclei of infected erythrocytes (Fig. 3e–l, o), are present

4 (32)

Trophozoites and binuclear meronts (Fig. 3e, f) do not produce clearly defined long outgrowths (Fig. 5a); if ameboid outgrowths are present, they do not exceed the main body of the trophozoites in length

5 (42)

Ends of growing macrogametocytes are similar in width (Fig. 4c–e, g–r)

6 (9)

Number of merozoites in mature erythrocytic meronts is relatively stable. Over 90% of the mature meronts contain 6 merozoites

7 (8)

Macrogametocyte nuclei are terminal in position (Fig. 4g). Refractive globules (Fig. 3h) are present in erythrocytic meronts

……………………………………………. P. parahexamerium [55]

8 (7)

Macrogametocyte nuclei are central or subcentral in position (Fig. 4o). Refractive globules are absent from erythrocytic meronts (Fig. 3p)

……………………………………………. P. hexamerium [1, 8, 55, 107]

9 (6)

Number of merozoites in mature erythrocytic meronts is variable

10 (37)

Growing and mature meronts assume various positions to the erythrocyte nuclei; they can be found in polar, sub-polar and lateral position in relation to the host cell nuclei

11 (38)

Binuclear erythrocytic meronts do not possess large (of size, which is similar to nuclei of the meronts), centrally located vacuoles (Fig. 3e). Macro- and microgametocytes are of similar shape, they assume similar positions in erythrocytes (Fig. 4g, h)

12 (39)

Gametocytes do not possess refractive globules

13 (16)

Erythrocytic meronts possess globules in natural infections (Fig. 3f, h–j)

14 (15)

The majority of trophozoites as well as developing and mature erythrocytic meronts possess one of circular shape, prominent (on average 0.5 µm² in area) pigment granule (Fig. 3q). Fan-like in shape mature meronts predominate

……………………………………………. P. unalis [49]

15 (14)

The majority of trophozoites, developing and mature erythrocytic meronts possess 1–4 (usually 2–3) small (< 0.5 µm² in area), of different size pigment granules (Fig. 3c, h). Fan-like in shape mature meronts (Fig. 3o) are uncommon

……………………………………………. P. vaughani [1, 8, 49, 55, 108]

16 (13)

Erythrocytic meronts do not possess globules in natural infections (Fig. 3g, n, o, r, s)

17 (18)

Fan-like mature meronts containing 7–8 merozoites are common (Fig. 3o); pigment granules in gametocytes are clumped together into a prominent group, which is predominantly of terminal position in the gametocytes (Fig. 4e, h)

……………………………………………. P. ashfordi [71]

18 (17)

Fan-like mature meronts containing 7–8 merozoites are absent; pigment granules in gametocytes are scattered or clumped, but position of these clumps is irregular (never predominantly terminal) in the gametocytes

……………………………………………. P. forresteri [8, 109]

19 (1)

Maximum number of merozoites in erythrocytic meronts is 4

20 (21)

Erythrocytic meronts do not possess globules in natural infections (Fig. 3g)

……………………………………………. P. bertii [8, 110]

21 (20)

Erythrocytic meronts possess globules in natural infections (Fig. 3f, h–l)

22 (23)

One small (< 0.5 µm in diameter) refractive globule present in the majority of meronts (Fig. 3f, h, j). Blue non-refractive globules (Fig. 3k, l) are absent from meronts. The cytoplasm in gametocytes is more or less homogenous, but never is granular-like (Fig. 4c) or globular-like (Fig. 4l, m) in appearance

……………………………………………. P. rouxi [1, 8, 52, 111]

23 (22)

Refractive globules (Fig. 3f, h–j) are absent from meronts. One blue non-refractive globule present in each advanced trophozoite (Fig. 3b), growing and mature meront (Fig. 3k, l). The cytoplasm in gametocytes is granular-like (Fig. 4c) or globular-like in appearance (Fig. 4l, m)

24 (25)

One large (size similar to parasite nuclei or greater) blue non-refractive globule present in each advanced trophozoite (Fig. 3b), growing and mature meront (Fig. 3l). The cytoplasm in macro- and microgametocytes is markedly globular-like in appearance (Fig. 4l, m). Average number of pigment granules in macro- and microgametocytes is close to 10

……………………………………………. P. megaglobularis [52]

25 (24)

One small (size smaller than parasite nuclei) blue non-refractive globule present in each advanced trophozoite, growing and mature meront (Fig. 3k). The cytoplasm in gametocytes is markedly granular in appearance, which is better visible in macrogametocytes (Fig. 4c); globular-like appearance of the cytoplasm (Fig. 4l, m) is not characteristic. Average number of pigment granules in macro- and microgametocytes is close to 5

……………………………………………. P. globularis [52]

26 (3)

Erythrocytic meronts, which lie free in the cytoplasm of host cell and do not touch the nuclei of infected erythrocytes (Fig. 3e–l, o), are absent. Erythrocytic meronts are strictly nucleophilic (Figs. 3n, s; 5q)

27 (40)

Both meronts (Fig. 3n, p, s, t) and gametocytes (Fig. 4a, d) are strictly nucleophilic

28 (29)

Large (≥ 1 mµ in length) pigment granules are present in gametocytes (Fig. 4d); both mature gametocytes (Fig. 4d) and meronts (Fig. 3n, t) do not displace nuclei of erythrocytes

……………………………………………. P. delichoni [72]

29 (30)

Large (≥ 1 mµ) pigment granules (Fig. 4d) are absent from gametocytes; mature meronts (Fig. 5q) or mature gametocytes (Fig. 5k) displace nuclei of erythrocytes

30 (31)

Fully-grown gametocytes do not fill erythrocytes up to their poles (Fig. 4h). Fully grown meronts displace nuclei of erythrocytes (Fig. 5q). Fully-grown gametocytes do not displace the nuclei of infected erythrocytes (Fig. 4h)

……………………………………………. P. nucleophilum [1, 8, 112,113,114]

31 (30)

Fully grown gametocytes fill erythrocytes up to their poles (Fig. 5k). Fully grown erythrocytic meronts do not displace or only slightly displace the nuclei of infected erythrocytes (Fig. 3t). Fully-grown gametocytes markedly displace the nuclei of infected erythrocytes laterally (Fig. 5k)

……………………………………………. P. paranucleophilum [8, 113]

32 (4)

Trophozoites and (or) binuclear meronts often produce clearly defined long outgrowths (Fig. 5a); the outgrowths exceed the main body of the trophozoites in length

33 (34)

One or two refractive globules present in advanced trophozoites and developing and mature meronts. Each globule has a clear rim at its periphery (Fig. 3i); macrogametocytes are markedly vacuolated in appearance (Fig. 4n)

……………………………………………. P. multivacuolaris [55]

34 (33)

Globules are absent from trophozoites and meronts, but vacuoles might be present

35 (36)

A large (> 1 µm in length) vacuole is present in trophozoites (Fig. 5a). Number of merozoites in erythrocytic meronts is relatively stable; approximately 95% of the meronts contain five merozoites. Pigment granules in gametocytes either randomly scattered throughout the cytoplasm or clumped into several small groups

……………………………………………. P. kempi [8, 115]

36 (35)

A large (> 1 µm in length) vacuole (Fig. 5a) is absent from trophozoites, but a small (< 1 µm in diameter) vacuole present occasionally. Number of merozoites in erythrocytic meronts is variable, but most often is equal to 8. Pigment granules in gametocytes frequently are clumped in a focus near one end of the gametocytes (Fig. 4h)

……………………………………………. P. columbae [1, 8, 116]

37 (10)

Growing and mature meronts are strictly of polar or subpolar position to the erythrocyte nuclei, and they usually do not adhere to the nuclei (Fig. 3q). Refractive globules present in grooving meronts, but often are invisible in mature meronts

……………………………………………. P. homopolare [58]

38 (11)

Binuclear erythrocytic meronts often possess one large (size similar to nuclei of the meronts), centrally located vacuole (Fig. 3e). In binuclear meronts, nuclei locate asymmetrically in relation to the vacuole (Fig. 3e). Shape of macro- and microgametocytes is different: microgametocytes are elongate (Fig. 4j), but macrogametocytes are not, and they are more or less roundish, lobulated or irregular in form parasites (Fig. 4b). Macrogametocytes usually take polar or subpolar position to nuclei of erythrocytes (Fig. 4b), and microgametocytes locate laterally to the nuclei of erythrocytes (Fig. 4j). Trophozoites possess one clear vacuole (Fig. 3a), which maintain in fully grown meronts (Fig. 3m)

……………………………………………. P. lucens [55]

39 (12)

Gametocytes possess refractive globules (Fig. 5h). Refractive circular globules present in macro- and microgametocytes

……………………………………………. P. accipiteris [53]

40 (27)

Meronts are strictly nucleophilic (Fig. 3p), but gametocytes are not (Fig. 4r). The majority of gametocytes do not adhere to nuclei of infected erythrocytes. Mature gametocytes markedly enclose nuclei of erythrocytes by their ends (Fig. 4r)

……………………………………………. P. homonucleophilum [117]

41 (2)

Maturing erythrocytic meronts, which displace host-cell nuclei, assume fan-like shape and possess elongate nuclei (Fig. 3v), are present. Number of nuclei in maturing fan-like meronts is about 10–12

……………………………………………. P. valkiunasi^a [56]

42 (5)

Ends of growing macrogametocytes are markedly different in width

……………………………………………. P. dissanaikei [1, 8, 118]