Novistrombidium sinicum n. sp. and Novistrombidium orientale n. sp. (Protozoa:Ciliophora): Two New Oligotrich Ciliates from a Mangrove Wetland, South China

WEIWEI LIU,a DAPENG XU,b,c XIAOFENG LIN,a JIQIU LI,a JUN GONG,a,d KHALED A.S. AL-RASHEIDe and WEIBO SONGa,b

aLaboratory of Protozoology, Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, South China Normal

University, Guangzhou 510631, China, andbLaboratory of Protozoology, Ocean University of China, Qingdao 266003, China, and

cDepartment of Biology, North Carolina Central University, North Carolina 27707, USA, anddDepartment of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom, and

eZoology Department, King Saud University, Riyadh 11451, Saudi Arabia

ABSTRACT. The morphology and infraciliature of two new marine oligotrich ciliates, Novistrombidium sinicum n. sp. and Novi-strombidium orientale n. sp., isolated from a mangrove wetland near Guangzhou, southern China, were studied from live and protargol-stained specimens. Novistrombidium sinicum is different from its congeners by the combination of the following characters: three pos-teriorly directed thigmotactic membranelles, one ellipsoidal macronucleus, the extrusomes equidistantly arranged, and the ventral kinetycommencing below the right end of the girdle kinety. The small-sized N. orientale can be separated from its congeners by two posteriorlydirected thigmotactic membranelles, one ellipsoidal macronucleus, the extrusomes equidistantly arranged, and the ventral kinety com-mencing below the right end of the girdle kinety.

Key Words. Infraciliature, marine ciliates, morphology, south China sea, Strombidiidae.

THE arrangement and composition of the somatic kineties isan important generic character for many oligotrichs (Agatha

2004; Jankowski 1978; Lynn and Montagnes 1988). Based on thefeature of ‘‘the girdle kinety is a round equatorial area with a largeventral gap, through which the ventral kinety extends,’’ Song andBradbury (1998) established the genus Novistrombidium. Later,by including the location of the oral primordium, Agatha (2003)improved its diagnosis: Strombidiidae with the left portion of thedextrally spiraled girdle kinety posterior to the oral primordiumand the ventral kinety longitudinally arranged. Currently, onlytwo species, Novistrombidium testaceum (Anigstein, 1913) Song& Bradbury, 1998 and Novistrombidium apsheronicum (Ale-kperov & Asadullayeva, 1997) Agatha, 2003 have been assignedto this genus (Agatha 2003; Song and Bradbury 1998).

During faunistic surveys of ciliates in mangrove wetlands ofSouth China, two oligotrich ciliates were sampled. After detailedobservations and comparison with known species, we concludethat they are new members of Novistrombidium. Morphologicaldescriptions of these two species are documented here.

MATERIALS AND METHODS

Samples were collected using 20-mm mesh plankton nets from amangrove wetland (1141040E, 221370N) near Guangzhou, south-ern China. Novistrombidium sinicum n. sp. was isolated in January2008 (salinity 20%, pH 7.5, and water temperature 17 1C) withmorphospecies ID No. WW08010304, genospecies ID No. GD-08010304, and SSrRNA GenBank accession No. FJ422989.Novistrombidium orientale n. sp. was found in March 2008(salinity 17%, pH 8.2, and water temperature 23 1C) with mor-phospecies ID No. WW08031804, genospecies ID No. GD-08031804, and SSrRNA GenBank accession No. FJ422988.

The behaviors of both species were observed in Petri dishesunder a dissecting microscope (Nikon, Tokyo, Japan). The pro-targol silver-staining method (Wilbert 1975) was used to revealthe ciliary pattern and the nuclear apparatus. Details of the cells invivo were observed using bright-field and differential interferencecontrast microscopy (Nikon) at 100–1,000X while counts andmeasurements on stained cells were done at 1,000X magnification(Xu et al. 2007). Drawings of stained specimens were performed

with the aid of a camera lucida. Terminology is mainly accordingto Agatha et al. (2005).

RESULTS

Novistrombidium sinicum n. sp. (Table 1 and Fig. 1–21). Thecell size is 50–60 � 30–35 mm in vivo, outline is broadly ellip-soidal and asymmetric because of the extrusome bulge around the

Table 1. Morphometric characterization of Novistrombidium sinicumn. sp. (first row) and Novistrombidium orientale n. sp. (second row).

Characters Min Max Mean SD n

Cell length 38 72 52.3 6.88 3318 32 25.2 4.17 31

Cell width 32 49 38.9 4.64 3312 22 17.8 2.82 31

Number of anterior membranellesa 24 29 25.6 1.01 3314 19 16.2 1.17 28

Number of ventral membranelles 9 12 10.1 0.72 315 8 6.2 0.61 29

Number of thigmotactic membranelles 3 3 3.0 0 352 2 2.0 0 21

Number of dikinetids in GK 48 82 69.2 7.18 3224 36 30.8 2.55 26

Number of dikinetids in VK 20 39 31.9 3.74 3314 22 17.1 2.14 24

Distance from apical cell end to cytostome 13 24 17.4 3.33 377 12 9.4 1.23 32

Distance from apical cell end to anteriorend of GK

18 32 22.7 3.89 3210 16 12.3 16.01 27

Distance from apical cell end to posteriorend of GK

31 60 43.5 6.12 3119 30 24.0 3.68 25

VK length 14 31 23.0 3.47 3110 16 12.5 1.97 25

Macronucleus length 18 29 22.5 2.92 338 16 11.4 2.23 31

Macronucleus width 12 20 15.4 2.11 355 14 8.2 1.75 31

All data based on protargol-impregnated and randomly selected spec-imens. Measurements in mm.

aNot including the thigmotactic membranelles.GK, girdle kinety; Max, maximum; Mean, arithmetic mean; Min, min-

imum; n, number of specimens investigated; SD, standard deviation; VK,ventral kinety.

Corresponding Author: X. Lin, Laboratory of Protozoology, SouthChina Normal University, Guangzhou 510631, China—Telephone num-ber: 186 20 8521 0644; e-mail: xlin@scnu.edu.cn

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J. Eukaryot. Microbiol., 56(5), 2009 pp. 459–465r 2009 The Author(s)Journal compilation r 2009 by the International Society of ProtistologistsDOI: 10.1111/j.1550-7408.2009.00425.x

cell (Fig. 1, 2, 9, 10). The cell is 3:4 dorsoventrally flattened(Fig. 3). Its anterior end is transversely truncated forming a shoul-der region with a prominent apical protrusion, ca 9 mm high,which shrank after fixation and staining. The posterior end isbroadly rounded (Fig. 1, 10).

The pellicle is delicate with a thin hemitheca that covers theposterior half of cell, but no polygonal platelet was observed. Thecytoplasm often contains many small globules (1–3 mm across)and food vacuoles with ingested algae and bacteria, which rendercells yellow to brown in color at low magnification (Fig. 1, 2).Extrusomes are prominent and acicular shaped, each about 10mmlong, equidistantly arranged (not in bundles) and inserted directlyanteriorly to the girdle kinety (Fig. 4, 14). On the lateral and dorsalsides, the extrusomes attach to the cortex in a conspicuous bulge;on the ventral side, they obliquely insert at the cortex in a shallowfurrow near the posterior end (Fig. 1, 2, 3, 10, 11, 12). There is noextra extrusome stripe on the posterior dorsal side. The macronu-cleus is positioned right of the mid-line, globular to broadly el-

lipsoidal shaped and contains many chromatin granules (Fig. 1, 7,8, 16). The micronucleus, cytopyge, and contractile vacuole werenot observed.

The locomotion is by rotating about the main cell axis in widespirals, interrupted by sudden changes in direction (Fig. 5). Oc-casionally, this ciliate crawls obliquely over debris, using its threethigmotactic membranelles for attachment of the ventral side.

The oral apparatus consists of an endoral membrane on the in-ner wall of the buccal lip and a conspicuous adoral zone of mem-branelles that surrounds the apical protrusion (Fig. 1, 7, 8, 9, 15).The buccal cavity is shallow, extending transversely to the rightand terminating about one-third of the way down the cell (Fig. 1,9, 10). The adoral zone of membranelles consists of anterior andventral parts, which are separated by three thigmotactic mem-branelles (Fig. 3, 7, 15, 16). The anterior part comprises 24–29,and the ventral part 9–12 membranelles, all of which are com-posed of three rows of kinetosomes. Cilia of the anterior mem-branelles are about 20 mm long, stretching perpendicularly to the

Fig. 1–8. Novistrombidium sinicum n. sp. from life (1–5) and after protargol impregnation (6–8). 1. Ventral view of a typical specimen. 2, 3. Dorsal(2) and left lateral (3) views, to show the three thigmotactic membranelles and the arrangement of extrusomes. 4. Extrusomes. 5. Swimming trace. 6.Pattern of somatic ciliature. 7, 8. Ventral (7) and dorsal (8) views of the same specimens showing the ciliary pattern. AM, anterior membranelles; AP,apical protrusion; E, endoral membrane; Ex, extrusomes; GK, girdle kinety; Ma, macronucleus; TM, thigmotactic membranelles; VK, ventral kinety;VM, ventral membranelles. Scale bars in Fig. 1–3, 6–8 5 20 mm, in Fig. 4 5 5mm.

460 J. EUKARYOT. MICROBIOL., 56, NO. 5, SEPTEMBER–OCTOBER 2009

main cell axis (Fig. 1, 9). The three thigmotactic membranellesdirected posteriorly are distinct in vivo due to their much longercilia. The cilia of the proximal thigmotactic membranelle arelongest, up to 35 mm long and the cilia of the distal one are short-est, about 30mm long (Fig. 1, 3, 13). The bases of the thigmotacticmembranelles are about 12 mm long, while the bases of the ventralmembranelles are 3–6 mm long, distinctly shorter than anterior

membranelles, which are about 8 mm long. The endoral membraneextends to the centre of the anterior protrusion, and is composed ofa single row of monokinetids (Fig. 7).

The somatic ciliature consists of one girdle kinety and oneventral kinety (Fig. 6, 7, 8, 18, 19). The girdle kinety originates inthe equatorial area posterior to the thigmotactic membranelles andextends transversely across right ventral and dorsal sides, then

Fig. 9–21. Micrographs of Novistrombidium sinicum n. sp. from life (9–15) and after protargol impregnation (16–21). 9. Ventral view of a typicalcell (Fig. N from Gao et al. 2009). 10. A slightly fat individual, showing the asymmetric cell shape; arrow marks the apical protrusion and arrowheadsindicate the bulge where extrusomes attach to the cortex. 11, 12. Ventral (11) and dorsal (12) views, to show the arrangement of extrusomes (arrows). 13.Ventral view; arrows indicate the three thigmotactic membranelles. 14. Extrusomes. 15, 16. Anterior portion of cell, to show the adoral zone of mem-branelles; note the three thigmotactic membranelles (arrows). 17. Ventral view showing the ventral kinety. 18, 19. Ventral (18) and dorsal (19) views, toshow the girdle kinety. 20, 21. Ventral view of early (20) and middle (21) dividers; arrows indicate the oral primordium. GK, girdle kinety; Ma, mac-ronucleus; VK, ventral kinety. Scale bars in Fig. 9, 18 5 30 mm; in Fig. 14 5 5mm.

461LIU ET AL.—ON TWO MARINE OLIGOTRICH CILIATES

inclines to the posterior end along the left ventral margin, ap-proaching orthogonally to the ventral kinety subterminally (Fig. 6,7, 8, 17, 18, 19). There are 48–82 widely spaced dikinetids in thegirdle kinety. The left basal body of each dikinetid bears a shortcilium, about 2 mm long (Fig. 7, 8). The ventral kinety, composedof 20–39 densely arranged dikinetids, is located on the right ven-tral side and commences below the right end of the girdle kinety(Fig. 6, 7, 8, 17, 18). Each dikinetid possesses one short cilium,about 2 mm in length, associated with the anterior kinetosome(Fig. 7). No extra kinety was detected.

Two divisional stages were observed: an early-middle dividerwith the oral primordium clearly beneath the cell surface wherethe right end of the girdle kinety is located (Fig. 20); a middle-later divider with oral primordium further developed in the pos-terior half of the cell at the time when the posterior portion of the

newly built adoral zone of membranelles bends to the right and thedifferentiation of membranelles is completed, forming the neworal structure for the opisthe (Fig. 21).

Novistrombidium orientale n. sp. (Table 1 and Fig. 22–42).The cell size is 30–40 � 15–25 mm in vivo. The cell is elliptical;the anterior end is domed to form a conspicuous apical protrusion,about 5 mm high, which may disappear or be undetectable afterprotargol impregnation; the posterior end of the cell is broadlyrounded to slightly narrowed (Fig. 22, 23, 30, 31). The cell is do-rsoventrally flattened about 3:4 (Fig. 24, 34).

The pellicle is thin and delicate. A hemitheca covers the cellfrom the posterior end to the girdle kinety; no polygonal corticalplatelets are recognizable. The cytoplasm is colorless to grayish,filled with little lipid globules. Many light-reflecting granules andingested algae are often contained, making the cell dark at lower

Fig. 22–29. Novistrombidium orientale n. sp. from life (22–26) and after protargol impregnation (27–29). 22. Ventral view of a typical specimen. 23,24. Dorsal (23) and left lateral (24) views, to show the thigmotactic membranelles and arrangement of extrusomes. 25. Swimming trace. 26. Extrusomes.27. Pattern of somatic ciliature. 28, 29. Ventral (28) and dorsal (29) views of same specimen showing the ciliary pattern. AM, anterior membranelles; AP,apical protrusion; E, endoral membrane; Ex, extrusomes; GK, girdle kinety; Ma, macronucleus; TM, thigmotactic membranelles; VK, ventral kinety;VM, ventral membranelles. Scale bars in Fig. 22–24 5 20 mm, 27–29 5 10 mm, in Fig. 26 5 4mm.

462 J. EUKARYOT. MICROBIOL., 56, NO. 5, SEPTEMBER–OCTOBER 2009

magnifications (Fig. 22, 34). Extrusomes are prominent and rodshaped, ca 8mm long, evenly arranged (not in bundles) as a band sur-rounding the posterior half of the cell, and attached to the cortex in aconspicuous bulge above the girdle kinety (Fig. 22, 23, 24, 26, 31, 32).There is no extra extrusome stripe in the posterior dorsal cell portion.The centrally located macronucleus is ovoid to ellipsoidal, mostly

containing numerous small chromatin granules (Fig. 22, 28, 29); inabout 30% of the individuals, four to five replication bands are equi-distantly arranged in the macronucleus (arrows in Fig. 36, 40). Thecontractile vacuole, cytopyge, and micronucleus were not observed.

The cells usually crawl over debris, using the thigmotacticmembranelles for attachment with the ventral side down; when

Fig. 30–42. Micrographs of Novistrombidium orientale n. sp. from life (30–36) and after protargol impregnation (37–42). 30. Ventral view of atypical cell; arrow marks the apical protrusion. 31, 32. Ventral (31) and dorsal (32) views, to show the arrangement of extrusomes (arrows). 33. Ventralview, arrows indicate the two thigmotactic membranelles. 34. Lateral view. 35. Anterior end of cell; arrows indicate the thigmotactic membranelles. 36.Macronucleus; arrows indicate the replication bands. 37, 39. Ventral views, to show the girdle kinety and the ventral kinety. 38. Dorsal view of anteriorpart of cell showing the girdle kinety. 40. Macronucleus; arrows indicate the replication bands. 41. Ventral view of anterior end of cell. Note thethigmotactic membranelles (arrows). 42. Ventral view of early dividers; arrow indicates the oral primordium. GK, girdle kinety; Ma, macronucleus; VK,ventral kinety. Scale bars in Fig. 30, 34 5 20 mm.

463LIU ET AL.—ON TWO MARINE OLIGOTRICH CILIATES

disturbed, they swim in narrow spirals by rotation about the mainaxis (Fig. 25).

The adoral zone of membranelles is divided into 14–19 ante-rior membranelles around the apical protrusion, two long thigmo-tactic membranelles, and 5–8 ventral membranelles (Fig. 28, 29).The buccal cavity is deep, extending obliquely to the right side ofthe cell (Fig. 22, 30). Cilia of the anterior membranelles are about15 mm long in vivo, and extend radially when swimming (Fig. 22,30). The thigmotactic membranelles connect the ventral mem-branelles and the anterior membranelles (Fig. 22, 24, 28, 33, 35,41). The cilia of the proximal thigmotactic membranelle are about22 mm and the cilia of the distal one are 18mm in length. The basesof the thigmotactic membranelles are about 7 mm long, slightlylonger than those of the anterior membranelles, which are about5 mm. The bases of the ventral membranelles are about 3–4mmlong (Fig. 28, 35, 41). The endoral membrane is on the inner wallof the buccal cavity, often difficult to recognize in protargol-stained specimens (Fig. 28).

All somatic kineties are composed of dikinetids, and the leftbasal body of each dikinetid bears a short cilium, about 2 mm long(Fig. 28, 29). The girdle kinety, consisting of 24–36 widely spaceddikinetids, extends from the right ventral side, equatorially acrossthe ventral and dorsal sides, then curves widely posteriad acrossthe left half of the ventral side, and terminates left of the ventralkinety (Fig. 27, 28, 29, 37, 38). The ventral kinety, composed of14–22 widely arranged dikinetids, extends along the right lateralmargin of the cell and commences below the right end of the gir-dle kinety (Fig. 27, 28, 37, 39). No extra kinety was detected.

Stomatogenesis commences with development of a cuneate,longitudinally orientated field of basal bodies in a subsurface tube,between the ventral membranelles and the left portion of girdlekinety (Fig. 42).

DISCUSSION

Taxonomic assignment of our forms. According to themorphological characteristics, especially the positional relation-ship of the ventral kinety (VK) and the girdle kinety (GK), our twoforms could be members of three genera: Spirostrombidium,Parallelostrombidium or Novistrombidium. However, none ofthese genera offer the definition exactly matching the character-istics of our forms (Agatha 2003, 2004; Song and Bradbury 1998).From a morphological point of view, we tentatively consider thegenus Novistrombidium to be the most appropriate taxon toaccommodate our two forms, N. sinicum n. sp. and N. orientalen. sp., despite the following differences compared with knowncongeners: (1) the location of VK relative to the GK (i.e. VKanteriorly through the gap of GK in Novistrombidium vs. VKanteriorly terminated below the right end of GK in our forms); (2)shape of the macronucleus (i.e. sausage like in the known twospecies of Novistrombidium vs. ovoid in our forms); and (3) thepresence of thigmotactic membranelles (i.e. absent in Novistrom-bidium vs. present in our forms) (Agatha 2003; Song and Brad-bury 1998). The phylogenetic trees inferred from small subunitrRNA gene sequences including these two forms have beenconstructed by Gao et al. (2009), in which N. sinicum was underthe name of Spirostrombidium sp.1 and N. orientale was under thename of Parallelostrombidium sp. Our two forms and N. testa-ceum did not group together in those phylogenetic trees (Gao et al.2009). However, the approximately unbiased (AU) test failed toreject the monophyly of Novistrombidium (P > 0.05; Zhang, pers.commun.). This indicates that our taxonomic assignments of thesetwo species are appropriate. A reclassification would require moreinformation on morphological features and gene sequences.

Comparison of Novistrombidium congeners. Novistrombidiumsinicum n. sp. and N. orientale n. sp. are distinguished from the

type species, N. testaceum in: (1) the cell shape (broadly ellip-soidal vs. heart- or bowl-shaped); (2) the arrangement of extru-somes (equidistantly arranged vs. grouped in bundles); (3) thenumber and shape of macronuclear nodules (1, ovoid vs. 2,sausage like); (4) the presence of thigmotactic membranelles(vs. absent); (5) the course of girdle kinety (spiraled once aroundthe cell vs. around equatorial area); and (6) the location of theanterior end of the ventral kinety (below the right end of thegirdle kinety vs. through the gap of girdle kinety) (Song andBradbury 1998).

Both new species can be separated from N. apsheronicum by:(1) the cell shape (broadly ellipsoidal vs. broadly obconical); (2)the arrangement of the anterior extrusomes (equidistantly ar-ranged vs. grouped in bundles); (3) the posterior extrusomes onthe dorsal side (absent vs. present); (4) the shape of the macro-nucleus (ellipsoidal vs. question mark shaped); (5) the thigmotac-tic membranelles (present vs. absent); and (6) the location of theanterior end of the ventral kinety (below the right end of the girdlekinety vs. through the gap of girdle kinety) (Agatha 2003).

In terms of the thigmotactic membranelles and dextrally spi-raled girdle kinety, N. sinicum is closely related to N. orientale.However, the former differs from the latter by: (1) the larger cellsize (60 � 35 vs. 35 � 20 mm in vivo); (2) the more thigmotacticmembranelles (3 vs. 2); (3) the posterior extension of the left endof the girdle kinety (toward right vs. toward posterior); and (4)much higher number of anterior membranelles (24–29 vs. 14–19)and ventral membranelles (9–12 vs. 5–8).

Comparison with similar species. Considering the thigmo-tactic membranelles and dextrally spiraled girdle kinety, threerelated marine species, Spirostrombidium cinctum (Kahl, 1932)Petz, Song & Wilbert, 1995, Spirostrombidium agathae Xu et al.,2006b and Parallelostrombidium paralatum Xu, Song & Warren,2006a should be compared with our new species.

Spirostrombidium cinctum differs from these two new species by:(1) the course of posterior portion of girdle kinety (crossing theposterior pole from the dorsal side vs. inclining to the posterior endacross the left ventral side); (2) the relative location of girdle andventral kinety in the posterior portion (in parallel vs. at an angle); (3)the pattern of extrusomes attachment sites in the posterior half of thecell (extending along the posterior dorsal margin vs. inclining to theposterior end across the left ventral side); and (4) the extra kinetyaround the ‘‘shoulder’’ area of the left side of the cell (present vs.absent) (Kahl 1932; Petz et al. 1995; Xu and Song 2006).

Compared with both new species, S. agathae: (1) has the pos-terior portion of the girdle and ventral kinety in parallel (vs. at anangle); (2) has the extra extrusomes along ‘‘shoulder’’ area on thedorsal side (vs. absent) (Xu et al. 2006b).

Parallelostrombidium paralatum can be separated from thesetwo new species by: (1) the course of the posterior portion of gir-dle kinety (in parallel with the ventral kinety and across the pos-terior pole to the dorsal side vs. at an angle to the ventral kinetyand extending across left ventral side); and (2) a much highernumber of ventral membranelles (15–19 vs. 9–12 in N. sinicumand 5–8 in N. orientale) (Xu et al. 2006a).

Class Oligotrichea Butschli, 1889Order Oligotrichida Butschli, 1889Family Strombidiidae Faure-Fremiet, 1970Genus Novistrombidiium Song & Bradbury, 1998

Novistrombidium sinicum n. sp.Diagnosis. Medium-sized marine Novistrombidium, in vivo

50–60 � 30–35mm; cell asymmetric broadly ellipsoidal with prom-inent apical protrusion; extrusomes equidistantly arranged; one el-lipsoidal macronucleus; about 25 anterior and 10 ventralmembranelles; three thigmotactic membranelles; ventral and girdle

464 J. EUKARYOT. MICROBIOL., 56, NO. 5, SEPTEMBER–OCTOBER 2009

kineties consisting of about 30 and 70 dikinetids, respectively; ven-tral kinety commencing below the right end of the girdle kinety.

Type location. Brackish water from a mangrove wetland(1141040E, 221370N) near Guangzhou, southern China.

Deposition of slides. Two permanent slides of protargol-im-pregnated specimens are deposited as a holotype and a paratype inthe Laboratory of Protozoology, South China Normal University,China with morphospecies ID numbers WW08010304–01 andWW08010304–02, respectively.

Etymology. The Latin word ‘‘sinica’’ (Chinese) indicates thatthis new species was first discovered in China’s territory.

Novistrombidium orientale n. sp.Diagnosis. Small marine Novistrombidium, cell size about

35 � 20 mm in vivo; cell ellipsoidal with apical protrusion; ext-rusomes equidistantly arranged; one ellipsoidal macronucleus;about 16 anterior and six ventral membranelles; two thigmotac-tic membranelles; ventral and girdle kineties consisting of about17 and 31 dikinetids, respectively; ventral kinety commencingbelow the right end of the girdle kinety.

Type location. Brackish water from a mangrove wetland(1141040E, 221370N) near Guangzhou, southern China.

Deposition of slides. One holotype and one paratype slides(morphospecies ID numbers: WW08031804–01, WW08031804–02,respectively) of protargol-impregnated specimens are deposited inthe Laboratory of Protozoology, South China Normal University,China.

Etymology. The Latin word ‘‘orientale’’ (oriental) indicatesthat this new species was first discovered in the Orient.

ACKNOWLEDGMENTS

This work was supported by the Natural Science Foundation ofChina (project numbers: 30870280, 30700069) and a grant fromthe Center of Excellence in Biodiversity, King Saud University.Special thanks are due to two anonymous reviewers and the ed-itors of the JEU for their constructive criticism and linguistic im-provements.

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Xu, D., Song, W., Lin, X. & Warren, A. 2006b. On two marine oligotrichciliates, Spirostrombidium agathae n. sp. and S. schizostomum (Kahl,1932) n. comb. from China, with a key to the identification of sevenwell-characterized Spirostrombidium spp. (Ciliophora: Oligotrichida).Acta Protozool., 45:433–442.

Xu, D., Song, W., Warren, A., Roberts, D. & Hu, X. 2007. Redescriptionsof two marine planktonic ciliates from China, Parastrombidium faurei(Kahl, 1932) Maeda, 1986 and Strombidium capitatum (Leegaard,1915) Kahl, 1932 (Ciliophora, Oligotrichea). Eur. J. Protistol., 43:27–35.

Received: 11/20/08, 03/04/09, 03/30/09; accepted: 03/30/09

465LIU ET AL.—ON TWO MARINE OLIGOTRICH CILIATES