Two New Species of Centrohelid Heliozoans: Acanthocystis costata sp. nov. and Choanocystis symna sp. nov. Author Zlatogursky, Vasily V. text Acta Protozoologica 2014 53 4 313 324 https://www.mendeley.com/catalogue/bf9b6251-8f7a-37a4-af28-d3023e35cd6d/ journal article 10.4467/16890027AP.14.021.1776 1689-0027 10371188 Acanthocystis costata sp. nov. ( Figs 1 , 2 ) Diagnosis: Cell body ca 9.5 µm in diameter. Axopodia 2–3 times longer than cell diameter. Length of spine scales 2.1–9.5 µm (on average 5.1 µm). There are straight scales as well as curved ones. Spine scales with four, five or six teeth. Plate scales with concave or, sometimes, parallel edges and rounded ends. Length of plate scales 1.3–3.7 (ca. 2.6) µm, width 0.9–1.9 (ca. 1.4) µm. Periphery of scale with a thickened border. Axial thickening and about fifty radial slits are present. Some scales with numerous small granules, probably present on one side of the scale only and therefore visible not on all scales. Cells actively move at the bottom of the culture dish or float in the culture medium. Sometimes fusions of two or three cells with a common food vacuole were observed. Large particles of unknown nature were observed in vacuoles of some individuals. Etymology: The species group name costata (from the Latin costatus ; ribbed), refers to the texture of plate scales. Type locality: Freshwater pool in the greenhouse of the botanical garden of St. Petersburg State University , St. Petersburg , North-Western Russia , 59°56′N , 30°17′E . Collected 22.12.2011 . Hapantotype: preparation ( Fig. 1A ) has been deposited in the Natural History Museum UK , accession number NHMUK 2013.6.28.2. Type sequence: GenBank accession number KF990486. Culture: CCAP 1504 /2 – the clonal culture from which type material and all the data provided in this paper were obtained . ZooBank LSID : urn:lsid:zoobank.org:act: CC3A8 4B0-1699-46BD-89E1-68A633AA7120 . Comparative diagnosis: The sculpture of the plate scales is a very characteristic feature of this species. Plate scales with similar radial slits are also described in A. myriospina and A. nichollsi . In A. myriospina these slits are observed only by Roijackers (cit. from Siemensma 1991 ) and only line drawing of the plate scale is published. But the quantity of slits on this drawing is nineteen, while in A. costata there are about fifty slits per scale. Probably this finding of Roijackers represents not an A. myriospina , but a new not yet described species. Anyway, even assuming, that slit-bearing scales are characteristic for A. myriospina , this species differs from A. costata in the quantity of slits and the morphology of spine scales. The similar quantity of slits is characteristic for scales of A. nichollsi . The size of plate scales is comparable, but not the same: 1.4–2.2 × 2.3–3.8 ( A. nichollsi from Siemensma 1991 ) vs 1.3–3.7 × 0.9–1.9 and appearance is alike, except of the presence of granules in A. costata . But morphology of spine scales between those two species is clearly different, because in A. nichollsi short spine scales with apexes, separated into arms and connected with flarings of scale shaft are present ( Nicholls 1983 ). Contrary, there is no any flarings on spine scales of A. costata . Table 1. Summary of characteristics of all described species of Acanthocystis and Choanocystis .
Species Plate scales Spine scales
1. A. antonkomolovi Leonov, 2010 oval, radial openings 2 long teeth
2. A. astrakhanensis Mikrjukov, 1993 oval 2 short teeth
3. A. bicornis Dürrschmidt, 1987 oval 2 types: short, secondary bifurcations; long, branches with inner denticles
4. A. clavata Dürrschmidt, 1987 oval tapering
5. A. cornuta Dürrschmidt, 1987 oval 2 branches with inner denticles
6. A. costata sp. nov oval, radial slits, granules 4–6 short teeth
7. A. dentata Leonov et Mylnikov, 2012 dumbbell 2 branches with 1 inner tooth each
8. A. dresscheri Siemensma et Roijackers, 1988 dumbbell, granules truncated 5–8 short teeth
9. A. dürrschmidtidae Wujek, 2003 oval, granules, marginal rim truncated
10. A. elenazhivotovae Leonov, 2010 oval, radial openings 2–3 short teeth
11. A. mikrjukovi Leonov, 2010 pear-shaped 2 branches with secondary bifurcations
12. A. mylnikovi Leonov, 2010 oval, granules 2–6 short teeth
13. A. myriospina Penard, 1890 First EM : Dürrschmidt, 1985 oval 3 sharp teeth
14. A. nichollsi Siemensma et Roijackers, 1988 oval, radial slits about 6 teeth with flarings
15. A. olgashelestae Leonov, 2010 oval or pear-shaped, granules 2 short teeth
16. A. pectinata Penard, 1889 First EM : Siemensma, Roijackers, 1988 oval, granules 2 types: short, 4–6 teeth, flarings, numerous; long, 2–3 teeth, rare
17. A. penardi Wailes, 1925 First EM : Nicholls, 1983 oval truncated 8–14 short teeth
18. A. polymorpha Dürrschmidt, 1985 dumbbell, granules two types: short, 5–8 teeth, flarings; long, with about 3 long teeth
19. A. pusilla (Dürrschmidt, 1987) Siemensma, 1991 dumbbell or pear-shaped, granules 4–7 teeth
20. A. quadrifurca Nicholls, 1983 oval, radial openings 4 sharp teeth
21. A. saphonovi Mikrjukov, 1994 bean-shaped 10–12 short teeth, spiral rib
22. A. spinifera Greeff, 1869 First EM : Siemensma et Roijackers, 1988 dumbbell 2–3 obtuse teeth
23. A. spinosa Cavalier-Smith et von der Heyden, 2007 oval 3 short teeth
24. A. takahashii Dürrschmidt, 1987 oval or pear-shaped 3 branches with small denticles
25. A. taurica Mikrjukov, 1997 oval 5 sharp teeth
26. A. tubata Dürrschmidt, 1987 oval about 12 short teeth, broad apex
27. A. turfacea Carter, 1863 First EM : Dürrschmidt, 1987 oval 2 long teeth
28. A. valdiviense Dürrschmidt, 1987 oval 4 teeth two types: short with long teeth; long with short teeth
29. A. wiasemskii Ostroumoff, 1917 First EM : Mikrjukov, 1994 bean-shaped tapering
Species Plate scales Spine scales
1. Choanocystis aculeata (Hertwig et Lesser, 1874) Siemensma et Roijackers, 1988 dumbbell papillate, truncated
2. Choanocystis antarctica Tikhonenkov et Mylnikov, 2010 oval spur at the bend point of the shaft, curved toward base
3. Choanocystis bicornioides Mikrjukov, 1995 dumbbell 2 branches with secondary bifurcations
4. Choanocystis curvata Cavalier-Smith et von der Heyden, 2007 oval 2–3 teeth, curved toward base
5. Choanocystis ebelii (Wujek et Elsner, 1992) Mikrjukov, 1997 rod-shaped pointed, granules
6. Choanocystis kareliensis Mikrjukov, 1994 dumbbell, granules pointed
7. Choanocystis lepidula Penard, 1904 First EM : Siemensma et Roijackers, 1988 oval, marginal rim truncated, curved toward base
8. Choanocystis malyutini Mikrjukov, 1995 oval, granules 3 branches
9. Choanocystis pantopoda (Penard, 1904) Siemensma, 1991 First EM : Dürrschmidt, 1987 oval 4–6 teeth
10. Choanocystis pelagica (Ostenfeld, 1904) Mikrjukov, 1994 oval, granules pointed, curved toward base
11. Choanocystis perpusilla (Petersen et Hansen, 1960) Siemensma, 1991 oval 2 (more rarely 3–4) small teeth
12. Choanocystis pertusa (Dürrschmidt, 1987) Siemensma, 1991 oval, radial openings 4 teeth
13. Choanocystis rhytidos (Dürrschmidt, 1987) Siemensma, 1991 oval or pear-shaped; radial slits 2–4 teeth
14. Choanocystis roijackersi Wujek, Saha, 2006 oval or slightly dumbbell 2–4 teeth, constriction near base-plate
15. Choanocystis rossica (Mikrjukov, 1995) Mikrjukov, 2002 oval or slightly dumbbell truncated
16. Choanocystis rotoairense (Dürrschmidt, 1987) Mikrjukov, 1995 oval, granules 4 teeth
17. Choanocystis rotundata ( Nicholls, 1983 ) Dürrschmidt, 1987 oval 10–20 small teeth
18. Choanocystis symna sp. nov. dumbbell 3–5 teeth
Table 2. Morphometry of Acanthocystis costata and Choanocystis symna .
Parameter Min Max Mean unweighted +/– SE n (i) n
A. costata sp. nov. , CCAP 1504/2 Cell diameter 5.8 12.0 9.5 ± 0.19 58 58
Radial scales length 2.1 9.5 5.1 ± 0.14 5 149
Plate-scales length 1.3 3.7 2.6 ± 0.05 5 83
Plate-scales width 0.9 1.9 1.4 ± 0.02 5 94
C. symna sp. nov. , CCAP 1597/1 Cell diameter 5.3 8.1 6.7 ± 0.10 50 50
Radial scales length 3.9 6.7 5.1 ± 0.49 6 111
Plate-scales length 4.4 5.0 4.7 ± 0.17 3 33
Plate-scales width 1.62 1.90 1.71 ± 0.092 3 33
All measurements in μm. Abbreviations : Max – maximum, Mean – arithmetic mean, Min – minimum, n – number of measurements, n (i) – number of individuals and SE – standard error of the mean.
Fig. 1. Acanthocystis costata spec. nov strain CCAP 1504/2. ( A ) Air-dried whole-mount of the cell. Type-slide NHMUK 2013.6.28.2. SEM (Scanning electron micrograph). Spine scales (ss) and plate scales (ps) are seen. Spine scales with four (ft), five (fit), and six (st) teeth can be found. Surface of plate scales is covered by numerous granules (g). ( B ) Living cell. Phase contrast. ( C ) Two individuals with a common food vacuole (fv), containing some vegetable material. Phase contrast. ( D ) Living cell compressed with a cover-slip. DIC (Differential interference contrast). Axopodia (a), contractile vacuoles (cv), microtubule-organizing center (MTOC), nucleus (n) and spine scales can be seen. ( E ) Scales of the air-dried specimen. Phase contrast. Scale bars: 1 μm (A), 10 μm (B–E). A. mylnikovi is similar to the new species in having spine scales with four, five or six teeth (however two or three teeth are also reported for A. mylnikovi ). But spine scales of A. costata are much shorter: 2.8–11.3 µm vs 5–17 µm for A. mylnikovi and plate scales of A. mylnikovi have no slits ( Leonov 2010 ). A. pectinata , A.polymorpha and several other species (see Table 1 ) have granules on plate scales similar to granules in A. costata . But in these species there are no slits on plate scales and morphology of spine scales is very different.