Studies on Three Diverse Frontonia Species (Ciliophora, Peniculida), with Brief Notes on 14 Marine or Brackish Congeners Author Pan, Xuming Author Liu, Weiwei Author Yi, Zhenzhen Author Fan, Xinpeng Author Al-Rasheid, Khaled A. S. Author Lin, Xiaofeng text Acta Protozoologica 2013 52 1 35 49 https://www.mendeley.com/catalogue/7e747b38-e86b-3f14-85d0-058b78439c1b/ journal article 10.4467/16890027AP.13.004.0832 1689-0027 13192853 Frontonia guangdongensis spec. nov. ( Fig. 1 ; Tables 1 , 2 ) Diagnosis: Brackish water Frontonia , about 160 × 35 μm in vivo , elongated body shape with right margin depressed in anterior third of body; length to width ratio about 4:1 to 5:1; small buccal field about 10 to 12% of body length; 62–75 somatic kineties; three or four vestibular kineties, four or five postoral kineties; peniculi 1 and 2 each with four rows, peniculus 3 with two rows; macronucleus ellipsoidal and located in central region of body; one contractile vacuole in mid-body region right of cell median. Type locality: A coastal shrimp-culturing area in Nansha ( 23°43′N , 113°33′E ), Guangdong province . Deposition of type slides: One slide containing the holotype (registration no. LWW-08110901-01) and several paratype slides (registration no. LWW-08110901-02) with protargol-impregnated specimens are deposited in the Laboratory of Protozoology , Ocean University of China , China . Fig. 1. Frontonia guangdongensis spec. nov. in vivo (A–D, H–M), after protargol (E–G, N–Q, S) and silver nitrate (R, T) impregnation. A , H – ventral view of a typical individual; B , I – different body shapes; C – part of a pellicle, to show extrusomes; D – extrusomes; E , F – infraciliature in ventral and dorsal views, macronucleus, and contractile vacuole pore of a holotype specimen; G – infraciliature of the buccal area; J – buccal area; K – ventral view, arrows show polygonal crystal granules, double arrowhead marks the single macronucleus, arrowhead exhibits the contractile vacuole; L – anterior end of cell, arrowheads mark the anterior suture; M – posterior part of the cell, arrowheads mark the caudal cilia, arrows show extrusomes; N , R – structure of the buccal region, arrows on R depict postoral kineties and arrowheads mark vestibular kineties; O – macronucleus and micronucleus, arrow marks micronucleus and arrowhead shows ingested algae; P , Q , T – anterior suture (arrowhead in P) and postoral suture (arrowheads in Q, T); S – somatic kineties. CVP – contractile vacuole pore; Ma – macronucleus; Mi – micronucleus; P1–P3 – peniculi 1, 2, 3; PK – postoral kineties, PM – paroral membrane; VK – vestibular kineties. Scale bars: A = 60 μm, E, F = 40 μm, H, I = 70 μm, J = 20 μm. Table 1. Morphometric data of Frontonia guangdongensis spec. nov. (upper row, bold font), F. ocularis Bullington, 1939 (middle row) and F. schaefferi Bullington, 1939 (lower row). Data according to protargol-impregnated specimens. All measurements in µm. Abbreviations: CV – coefficient of variation in %, n – number of specimens measured, SD – standard deviation.

Character	Min	Max	Mean	SD	CV	n
Body length	152	175	164.9	11.1	7.6	23
88	110	95.5	4.8	4.9	24
74	101	88.7	7.1	7.9	20
Body width	45	58	49.8	7.4	13.4	23
45	55	47.9	2.9	6.3	24
34	60	44.3	6.1	13.5	20
Number of	52	65	61.4	5.8	7.9	19
somatic kineties	93	107	95.7	9.6	12.8	18
59	80	69.2	12.1	13.8	18
Number of	3	4	3.1	0.3	8.7	15
vestibular kineties	3	3	3	0	0	14
3	3	3	0	0	14
Number of	4	5	4.1	5.8	7.9	14
postoral kineties	3	4	3.5	0.5	14.6	13
5	5	5	0	0	12
Number of ciliary rows in	4	4	4	0	0	15
peniculus 1	4	4	4	0	0	16
4	4	4	0	0	15
Number of ciliary rows in	4	4	4	0	0	15
peniculus 2	4	4	4	0	0	16
4	4	4	0	0	15
Number of ciliary rows in	2	2	2	0	0	14
peniculus 3	2	2	2	0	0	14
2	2	2	0	0	15

Etymology: The species name ‘ guangdongensis ’ refers to the location where this organism was first isolated. Description: Cell in vivo distinctly elongate, usually about 150–170 × 35–40 μm, with ratio of length to width about 4:1 to 5:1 ( Fig. 1A, H ). Right margin slightly depressed in anterior third of body ( Fig. 1A, B, H, I ). Dorsoventrally flattened about 5:4. Buccal cavity small and shallow, elliptical to triangular in outline, about 20 × 11 µm in size, 10 to 12% of body length ( Fig. 1G ). Cytoplasm grayish with many large (6–10 µm across), black, polygonal crystal granules. Food vacuoles (10– 12 µm across) and ingested algae distributed randomly in cytoplasm ( Fig. 1A, K ). Macronucleus ellipsoidal, about 20 μm × 15 μm, located in mid-region of body ( Fig. 1A, O ). Single micronucleus located near end of macronucleus, spherical, about 5 µm in diameter ( Fig. 1O ). Single contractile vacuole in mid-body region right of cell median, about 7 μm in diameter, contracting at about one minute intervals ( Fig. 1A, K ); no collecting canals observed; one contractile vacuole pore located on right-dorsal surface ( Fig. 1F ). Two types of extrusomes, spindle (about 8 µm long) and round (2 µm across), densely arranged beneath pellicle ( Fig. 1C, D, M ); somatic cilia generally about 6 µm long, cilia in caudal region being longer than others at approximately 10 µm long ( Fig. 1M ). Locomotion by gliding on substrate or by swimming while rotating about long body axis. Table 2. Comparison of marine or brackish Frontonia species isolated in China.

Species	Body length	Number of	Data sources
in vivo (µm)	somatic	ciliary rows	vestibular	postoral	contractile
kineties	in peniculi 1, 2, kineties and 3		kineties	vacuole
F. subtropica Pan et al ., 2012	180–230	104–114	4, 4, 4	5	5	1	Pan et al. (2013)
F. magna Fan et al ., 2011	200–410	165–216	4, 4, 4	5–6	4–7	1–2	Pan et al. (2013)
F. canadensis Roque and Puytorac, 1972	120–150	77–88	4, 4, 4	3–4	5	1	Pan et al. (2012)
F. sinica Fan et al ., 2013	100–200	100–119	4, 4, 2	5–6	3–5	1	Fan et al. (2013)
F. pusilla Fan et al ., 2013	70–100	70–77	4, 4, 2	4	3	2	Fan et al. (2013)
F. mengi Fan et al ., 2011	150–242	48–60	5, 5, 2	3	5	1	Fan et al. (2011)
F. tchibisovae Burkovsky, 1970	80–180	110–130	4, 4, 4	4	7	1	Long et al. (2008)
F. lynni Long et al ., 2005	100–210	71–83	4, 4, 5	3	5	1	Long et al . (2005)
F. didieri Long et al ., 2008	100–150	61–71	4, 4, 3	3	3–5	1	Long et al. (2008)
F. multinucleata Long et al ., 2008	70–120	58–67	4, 4, 4	3	4–5	1	Long et al . (2008)
F. elegans Fan et al., 2013	75–90	69–78	4, 4, 3	4	3	2	Fan et al . (2013)
F. guangdongensis spec. nov.	150–170	52–65	4, 4, 2	3–4	4–5	1	present work
F. ocularis Bullington, 1939	115–140	93–107	4, 4, 2	3	3–4	2	present work
F. schaefferi Bullington, 1939	95–100	59–80	4, 4, 2	3	5	1	present work

Somatic ciliature as shown in Fig. 1E, F, G, P–T . About 52 to 65 longitudinal somatic kineties, commencing at anterior end of cell, forming a conspicuous anterior suture that extends from anterior end of buccal cavity to dorsal side ( Fig. 1E, F, P, S ); posterior part of somatic kineties terminating below posterior region of oral apparatus forming the postoral suture ( Fig. 1G, Q, T ). Three to four vestibular kineties with close-set dikinetids ( Fig. 1G, R ). Four or five postoral kineties left of postoral suture, beginning anteriorly below buccal cavity and gradually shortening from left to right ( Fig. 1G, R ). Buccal apparatus as shown in Fig. 1G, N, R . Three conspicuous peniculi (P1–3) located on left wall of shallow buccal cavity, slightly curved to right at anterior end. Peniculi 1 and 2 about equally long, parallel to each other, and each composed of four rows of kinetosomes. Peniculus 3 composed of two kineties, right one of which extends entire length of buccal cavity, left one extending only to about anterior 4/5 of cavity length ( Fig. 1G, N ). Double-rowed paroral membrane on right side of buccal cavity: inner row composed of densely arranged monokinetids, outer row composed of loosely arranged dikinetids ( Fig. 1G, R ). Comparison and remarks: There are three species that closely resemble Frontonia guangdongensis spec. nov. in terms of the conspicuously elongated body shape: F. mengi Fan, 2011 , F. pallida Czapik, 1979 and F. microstoma Kahl, 1931 . Frontonia mengi differs from F. guangdongensis in three respects. Firstly, its body size in vivo is larger (250 × 45 μm vs. 160 × 35 μm); secondly, it has more kinety rows in peniculi 1 and 2 (each row has five in F. mengi vs. four in F. guangdongensis ): thirdly, the contractile vacuole of F. mengi is located in the posterior third of the cell, whereas in F. guangdongensis it is located in the mid-body region ( Fan et al. 2011a ). Frontonia pallida can be clearly distinguished from F. guangdongensis by the following combination of characteristics: F. pallida has three kinety rows in peniculus 2, whereas F. guangdongensis has four; F. pallida has a funnel-shaped cytopharynx (vs. absent in F. guangongensis ); F. pallida ’s contractile vacuole is to the left of the cell median, whereas it is to the right in F. guangdongensis ( Czapik 1979 , Dragesco and Dragesco-Kernéis 1986 ). Frontonia guangdongensis spec. nov. can also be easily separated from F. microstoma Kahl, 1931 in having only a single contractile vacuole with no canals whereas the latter has two contractile vacuoles with associated canals. Frontonia guangdongensis also has fewer somatic kineties (52–65 vs. 110–120 in F. microstoma ) and fewer kinety rows in peniculus 3 (2 vs. 3 or 4) ( Roque 1961 , Carey 1992 ).