Frontonia multinucleata, Long, Hongan, Song, Weibo, Al-Rasheid, Khaled A. S. & Wang, Yangang, 2008

Long, Hongan, Song, Weibo, Al-Rasheid, Khaled A. S. & Wang, Yangang, 2008, Taxonomic studies on three marine species of Frontonia from northern China: F. didieri n. sp., F. multinucleata n. sp. and F. tchibisovae Burkovsky, 1970 (Ciliophora: Peniculida), Zootaxa 1687, pp. 35-50 : 41

Frontonia multinucleata n. sp.

( Figs. 4–6 ; Table 1 )

Diagnosis: marine Frontonia in vivo 70–120 × 40–75 µm, dorsoventrally flattened about 2:1. 58–67 somatic, 3 vestibular and 4–5 postoral kineties. 3 peniculi each with 4 kineties. 2–4 globular macronuclear nodules. Single contractile vacuole located in posterior 1/3 of cell length.

Type location: A clear sandy beach (salinity 30 ‰) of Qingdao, China.

Type slides: One holotype with silver nitrate impregnated specimens (slide number: 2007:5:17:2) is deposited in the Natural History Museum, London, UK, and one paratype (slide number: 2006060101-2) is deposited in the Laboratory of Protozoology, Ocean University of China.

Etymology: This species is the first one in Frontonia which has more than one macronucleus (2–4). Thus, it is named according to this character: multi- (many), nucleata.

Description: Size in vivo about 70–120 × 40–75 µm. Cell shape rather constant, ellipsoidal in outline when viewed from ventral side ( Figs. 4 A, 4B; 5A, 5D). Dorsoventrally flattened about 2:1. Extrusomes spindle-shaped, about 8 µm long (20–25 µm long after being ejected, Fig. 5 B), densely arranged in cortex ( Figs. 4 A, 4B; 6C). Somatic cilia about 8 µm long. Cytoplasm colorless or grayish, often full of tiny granules, especially in caudal part ( Figs. 4 A, 4B; 5A, 5D). In all specimens observed from the culture which maintained for about 2 weeks, macronuclear nodules always in 2–4, yet mostly 4, generally globular in shape and about the same size, grouped or sparsely distributed ( Figs. 4 A, 4B, 4G, 4I; 6B, 6E, 6F). One large contractile vacuole located in posterior 1/3 of cell length, ca. 15 µm in diameter ( Figs. 4 A, 4B, 4E, 4J; 5E).

Movement mainly by gliding back and forth on substrate; when swimming, moderately rapid with rotation around the long axis of the cell.

Infraciliature as shown in Figs. 4 I–K. Both anterior and postoral sutures conspicuous, which extend onto dorsal side ( Fig. 4 C, 4I, 4J). On average 63 somatic kineties; 4–5 postoral kineties (PK, Figs. 4 H, 4I, 4K; 6N); 3 vestibular kineties, conspicuously short ( Figs. 4 H, 4I, 4K; 6J, 6L). Single CVP right dorsally located, at approximately posterior 1/3 of cell length ( Figs. 4 C; 6G, 6K).

Triangular buccal cavity occupying about 1/5 of body length. Peniculus 1–3 about equally long, all with 4 kineties; among them, P3 curved to right whose length becomes conspicuously shorter from right to left ( Figs. 4 F, 4H, 4I, 4K; 6D, 6H). Double-rowed paroral membrane on right side of buccal cavity ( Figs. 4 H, 4I, 4K; 6L). Argentophilic line positioned parallel to paroral membrane ( Fig. 4 H). Silverline system as quadrangular cortical meshes ( Fig. 6 I).

Comparison: Frontonia multinucleata n. sp. is the only one among members of the genus, which has consistently several macronuclear nodules (vs. single in all other known congeners). Hence, the new species is easily recognizable ( Fig. 10 C, 10D, 10I, 10J, 10K, 10M, 10N, 10R, 10S; Table 2).

Figures

FIGURE 4. Frontonia multinucleata n. sp. from living cells (A, B), after silver nitrate (C, F, H, K), silver carbonate (I, J) and protargol (D, E, G) impregnations. (A, B) Ventral views of typical specimens. (C) Dorsal view, to show the contractile vacuole pore (arrowhead). (D, E) Side views, to show the fibers connected with the buccal and postoral suture area. Note the contractile vacuole is near the dorsal side. (F) Detailed structure of the peniculus 3. (G) To show the different situation of the macronuclear nodules. (H) The oral apparatus, note the two-rowed paroral membrane (PM) and the vestibular kineties (VK), in which the anterior part consists of monokinetids. (I, J) The infraciliature of ventral and dorsal (ventral-to-dorsal) side of the same specimen, to show the postoral suture (arrows in I and J), and the contractile vacuole. (K) Ventral view, note the long cytopyge (arrowheads). SL = silver line. Scale bars = 30 µm.

FIGURE 5. Frontonia multinucleata n. sp. from life (A – E). (A, D) Typical individuals. (B) To show the ejected extrusomes. (C) Extrusomes beneath the pellicle. (E) Lateral view, to show the contractile vacuole (arrow). Scale bars in (B) = 15 µm; in (D) = 45 µm; in (A, E) = 50 µm.

FIGURE 6. Frontonia multinucleata n. sp. after silver carbonate (A – C, E, F) and silver nitrate (D, G, H – N) impregnations. (A, B, E, F, M) Ventral and dorsal views of different cells. Note the macronuclear nodules (arrows). (C) Part of pellicle, arrow marks the extrusome. (D, H) Oral apparatus. Arrowheads mark the posterior ends of kinety rows in P 3, which are in different lengths. (G, K) To point the CVP (arrowheads). (I) Detail of the silverline system. (J, L) Buccal area, to show the vestibular kineties (arrowheads) and the paroral membrane (arrow in L). (N) Structures posterior to the oral apparatus. Note the postoral kineties (arrowheads) and the cytopyge (arrow). Scale bars in (M) = 30 µm; in (A, E, F) = 45 µm; in (K) = 50 µm.

FIGURE 10. Frontonia species from living cells (C, D, G, I, K, O, Q) and after silver nitrate impregnations (B, E, F, H, J, L, N, P). (A, B) F. azerbaijanica Alekperov, 2005 (after Alekperov 2005). (C) F. bullingtoni Dragesco, 1960 (after Dragesco 1960). (D) F. c a n e t i Dragesco, 1960 (after Dragesco 1960). (E, F) F. elongata Burkovsky, 1970 (after Burkovsky 1970 b). (G, H) F. frigida Petz et al., 1995 (after Petz et al. 1995). (I, J) F. l y n n i Long et al. 2005 (after Long et al. 2005). (K, L) F. m a r i n a Fabre-Domergue, 1891 (K after Dragesco 1960; L after Roque 1961). (M, N) F. m a r i s a l b i Burkovsky, 1970 (after Burkovsky 1970 a). (O, P) F. s a l m a s t r a Dragesco and Dragesco-Kernéis, 1986 (after Dragesco & Dragesco-Kernéis 1986). (Q) F. vacuolata Dragesco, 1960 (after Dragesco 1960). (R) F. vernalis Bullington, 1939 (after Bullington 1939). (S) F. canadensis Roque and Puytorac, 1972 (after Roque & Puytorac 1972). Scale bars in (C) = 25 µm; in (M) = 30 µm; in (S) = 50 µm; in (E) = 60 µm; in (G) = 90 µm; in (D, K, Q, R) = 100 µm; in (A) = 150 µm.