Chaenea sinica, Fan & Xu & Gu & Li & Al-Farraj & Al-Rasheid & Hu, 2015

Fan, Xinpeng, Xu, Yuan, Gu, Fukang, Li, Jiqiu, Al-Farraj, Saleh A., Al-Rasheid, Khaled A. S. & Hu, Xiaozhong, 2015, Morphology of Two Novel Species of Chaenea (Ciliophora, Litostomatea): Chaenea paucistriata spec. nov. and C. sinica spec. nov., Acta Protozoologica 54 (2), pp. 97-106 : 102-103

Chaenea sinica spec. nov. ( Figs 4 , 5 ; Table 1)

Diagnosis: Extended cell size in vivo usually about 200 × 20 µm. On average 19 somatic kineties. Dorsal brush rows 1–4 consisting of 3–7, 10 or 11, 11–13, and 3–6 dikinetids, respectively. About 71–164 macronuclei.

Type locality: Coastal waters of Bohai Bay (37°37’N, 121°22’E), China .

Type material: A protargol slide containing the holotype specimen marked with an ink circle has been deposited in the Laboratory of Protozoology , Ocean University of China (Registry no. WYG2006032701) .

Etymology: The species-group name sinicus, -a, -um [m, f, n] reflects the fact that this organism was discovered in China.

Description: Extended cell size about 140–240 × 14–25 µm in vivo, with a length:width ratio of about 10–13:1; cell flexible and contractile; anterior body portion slightly narrowed and posterior part rounded ( Figs 4A, C , 5A–E ). Oral bulge inconspicuous ( Fig. 5A–C ). 71–164 ellipsoid macronuclei, with size about 2–4 × 1–2 µm, scattered in cytoplasm ( Figs 4F , 5N ). Single contractile vacuole located at the posterior body end ( Figs 4A, C , 5B ). Extrusomes rod-like, about 6–8 µm long, attached in batches to oral bulge, and scattered in cell ( Figs 4A, C , 5F, G ); extruded ones can be observed outside oral bulge, about 12–16 µm long ( Figs 4F , 5L ). Cortex flexible with distinct furrows present in some contracted specimens ( Fig. 5E ). Cell colour greyish due to packed food vacuoles, ca. 10 µm in diameter, and cytoplasmic granules, ellipsoid or round, ca. 1–4 µm in diameter ( Figs 4A, C , 5C ). Movement by slowly crawling on bottom of Petri dish, with anterior body portion continually contracting. 17–21 somatic kineties mainly consisting of monokinetids and extending the entire body length, each of which consists of 6–9 narrowly spaced oralized somatic monokinetids and 89–188 ordinarily spaced somatic monokinetids ( Figs 4D, E , 5H–K ). Somatic cilia about 5–6 µm long ( Fig. 5D ). Four dorsal brush rows consisting of 3–7, 10 or 11, 11–13, and 3–6 dikinetids respectively ( Figs 4B , 5H–J ). Cilia of dorsal brush undetectable in living cells, but observable in protargol stained specimens and about 2.5 µm long ( Figs 4B , 5H–J, M ). Circumoral kinety inconspicuous, composed of dikinetids which are at anterior end of each somatic kinety ( Figs 4D, E , 5I ). Nematodesmata, which can be observed after protargol staining, arising from circumoral kinety ( Figs 4F , 5I ).

Comparison: Considering the cell size, the number of macronuclei and somatic kineties, Chaenea sinica spec. nov. can be distinguished from most congeners. But, Chaenea sp. sensu Petz et al., (1995) and Chaenea robusta Kahl, 1930 need to be compared with our new species.

Although no information regarding its living cell is available, Chaenea sp. sensu Petz et al. (1995) still differs from the new form in possessing longer extrusomes (12–15 µm vs. 6–8 µm) and more dikinetids, in particular in the dorsal brush rows (22–28, 25–30, 25–32, 24–29 vs. 3–7, 10 or 11, 11–13, 3–6). These two species can therefore be separated ( Figs 3G, H ; Table 2; Petz et al. 1995).

Chaenea robusta can be distinguished from the new species by having: (1) a longer body (300–400 µm vs. 140–240 µm), (2) longer dorsal brush cilia (8 µm vs. ca. 2.5 µm) and extrusomes (12–15 µm vs. 6–8 µm), and (3) fewer somatic kineties (about 15 vs. 19 on average) ( Fig. 3F ; Table 2; Kahl 1930).

Figures

Figs 3A–M. Morphology of some closely-related congeners of Chaenea paucistriata spec. nov. and Chaenea sinica spec. nov. A–D – C. teres (from Petz et al., 1995), general view of living cell (A), overview of ciliary pattern (B), detail of ciliary pattern in anterior body end (C), surface view showing cortical granulation (D); E – C. simulans (from Kahl, 1930); F – C. robusta (from Kahl, 1930) G, H – Chaenea sp. (from Petz et al., 1995), detail of ciliary pattern in anterior body (G), overview of ciliary pattern (H); I–K – C. stricta (from Foissner, 1984), detail of ciliary pattern in anterior body (I), general view (J), overview of ciliary pattern (K); L, M – C. vorax (from Song and Packroff, 1997), general view (L), overview of ciliary pattern (M). B – dorsal brush, B1–4 – dorsal brush rows 1–4, CG – cortical granules, CK – circumoral kinety, CV – contractile vacuole, E – extrusomes, Ma – macronuclei, OB – oral bulge, SK – somatic kinety. Scale bars: 100 µm (A, H, L), 50 µm (B, J, K, M), 150 µm (E, F).

Figs 4A–F. Chaenea sinica spec. nov. in vivo (A, C) and after protargol staining (B, D–F). A – typical extended individual; B – detail of anterior part of dorsal ciliary pattern; C – contracted individual; D, E – overview of ciliary pattern of ventral (D) and dorsal (E) side; F – distribution of macronuclei, extrusomes, and nematodesmata. B1–4 – dorsal brush rows 1–4, CK – circumoral kinety, CV – contractile vacuole, E – extrusome, Ma – macronuclei, N – nematodesmata, SK – somatic kinety. Scales bars: 50 µm.

Figs 5A–N. Chaenea sinica spec. nov. in vivo (A–G) and after protargol impregnation (H–N). A, B – typical individuals; C–E – contracted and twisted cells; F, G – rod-shaped extrusomes attached to oral bulge (F) and scattered in cytoplasm (G); H–J – ciliary pattern of anterior body end, showing circumoral kinety, dorsal brush rows 1–4, and nematodesmata; K – middle part of body, showing somatic kineties; L – anterior body end, arrowheads denote the extruded extrusomes outside the oral bulge; M – anterior body end, arrowhead marks cilia of the dorsal brush; N – many scattered macronuclear nodules throughout cytoplasm (arrowheads). B1–4 – dorsal brush rows 1–4, CK – circumoral kinety, CV – contractile vacuole, E – extrusome, N – nematodesmata, SK – somatic kinety. Scales bars: 100 µm.