Thuricola kellicottiana ( Stokes 1887 ) Kahl, 1935

Lu, Borong, Ji, Daode, Sheng, Yalan, Song, Weibo, Hu, Xiaozhong, Chen, Xiangrui & Al-Rasheid, Khaled A. S., 2018, New discoveries of the genus Thuricola Kent, 1881 (Ciliophora, Peritrichia, Vaginicolidae), with descriptions of three poorly known species from China, Acta Protozoologica 57 (2), pp. 123-143 : 127-132

Thuricola kellicottiana ( Stokes 1887) Kahl, 1935

( Figs 4A–Q , 5A–T , Table 1)

1884 Thuricola innixa Stokes, 1882 –Kellicott, Proc. Amer. Soc. Microsc., Seventh Annual Meeting., 6: p. 120, Pl.3: Fig. 5 .

1887 Thuricolopsis kellicottiana spec. nov. –Stokes, Proc. Amer. Soc. Microsc., p. 251, Fig. 17.

1888 Thuricolopsis kellicottiana Stokes, 1887 – Stokes, J. Trenton Nat. Hist. Soc., p. 253–254, pl. 9: Fig.12.

1904 Cothurnia crystallina Ehrbrg. –Entz, Mat. Naturwiss. Ber. Ungarn., 19: p. 140–141, Fig. 10g.

1914 Cothurnia castellensis –Penard, Mém. Soc. Phys. Hist. Nat. Genève, 37: p. 59–60, Pl. 3, Figs 9–11, 13,14.

1922 Cothurnia kellicottiana Stokes –Penard, Georg & Cie, Genève, p. 290, Fig. 272.

1935 Thuricola (Thuricolopsis) kellicottiana ( Stokes 1887) –Kahl, Tierwelt Dtl., p. 785, Fig. 145: 5–6.

1951 Thuricola amphora n. sp. –Sommer, Arch. Hydrobiol., p. 410–411, Pl. 20, Fig. 36.

1970 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Nusch, Arch. Hydrobiol., 37: p. 313, Fig. 33.

1971 Thuricola amphora Sommer, 1951 –Stiller, Peritricha. Fauna Hung., 105: p. 214, Fig. 131c.

1980 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Trueba, Beaufortia, 30: p. 131–132, Figs 2e , 3c, d .

1982 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Bernerth, Cour. Forsch.-Inst. Senckenberg., 57: p. 170.

1988 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Foissner, Hydrobiologia, 166: p. 44 (record only).

1992 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Foissner et al., Landesamtes Wasserwirtsch., 278–280.

2016 Thuricola kellicottiana ( Stokes 1887) Kahl, 1935 –Shen & Gu, Fauna Sinica, Invertebrata, 45: p. 333–334. Pl. CLI, Fig. 456a–e.

Although Thuricola kellicottiana had been reported several times, studies have not been thorough and its morphology remains vague ( Stokes 1887). Thus, a redescription is necessary for the sake of clarification.

Emended diagnosis: Lorica colourless and ca. 160–290 μm long, elliptical to sub-circular in cross-section, nearly symmetrical on wider side and asymmetrical on narrower side. Two anisometric valves in upper third of lorica, larger valve with a spine in the middle; anterior third portion inclined with convex un- der aperture on secondary valve side, posterior portion tapering to base with two annular bulges to form a long slender rear; aperture clearly elliptical, base expanded. Zooid ca. 180–435 × 20–35 μm in vivo. Stalk about 15 μm long. Peristomial lip single-layered and strongly everted. Contractile vacuole dorsally located. Row 1 in infundibular polykinety 3 about twice the length of the other two. Transverse silverlines numbering 95–105 from peristome to trochal band, 100–110 from trochal band to scopula.

Voucher slides: Two voucher slides with protargol stained specimens (registration number: LU20170310- 03-01-02) have been deposited in the Laboratory of Protozoology, Ocean University of China.

Description: One or two trumpet-shaped zooids that taper towards the scopula, 230–380 × 20–30 μm (n = 9) in vivo ( Figs 4A–C , 5A–G ). Zooid very flexible and can bend extensively ( Fig. 5G ). When disturbed, zooid contracts and becomes ellipsoid or broadly conical in outline ( Fig. 5I, K, J ). Single-layered peristomial lip relatively thin and conspicuously everted, about 40–48 μm across ( Figs 4A–C , 5A–G ). Peristomial disc obliquely elevated above persitome ( Figs 4A–C , 5A–G ). Trochal band forming a circular bulge in mid-region of zooid ( Fig. 4C, F ). About 95–105 striations from peristome to trochal band and 100–110 striations from trochal band to scopula (counted from live cells, n = 5).

One contractile vacuole located at the same level as peristomial lip and on the dorsal wall of infundibulum ( Figs 4A , 5E, F ). Cytoplasm hyaline and contains nu- merous small granules and several food vacuoles ( Figs 4A, B , 5A–G ). Food vacuoles spindle-shaped when freshly detached from cytostome.

Macronucleus vermiform, extends almost entire length of zooid, relatively straight but curved transversely above peristomial lip, widens gradually towards anterior end ( Figs 4C, G , 5Q, R ). Due to shrinkage during fixation, macronucleus in protargol stained specimens is more twisted than in vivo ( Figs 4G , 5Q, R ).

Stalk about 15 μm long in average, both ends slightly expanded ( Figs 4A–C , 5A–G ).

Lorica hyaline, about 190–225 μm long. Narrow side about 44–50 μm across and wide side about 51–54 μm across; wall smooth and colourless. Viewed from the narrower side, the upper third portion of lorica inclined ( Figs 4A, B, D , 5I, O ). Aperture slightly everted and elliptical. Lorica conspicuously convex under aperture on secondary valve side and with a bulge in region above base of main valve ( Figs 4A, B, D , 5I, O ). Viewed from the wider side, lorica approximately symmetrical. Posterior region tapering and step-like ( Figs 4A–E , 5A–G, I–L, P ). Lorica widened at base ( Figs 4A–E , 5A–G, I–L, P ). One main valve and one secondary valve located in the upper third of lorica. Viewed from the wider side, valves include some longitudinal fibril-like elements ( Figs 4C, E , 5K, L ). Large main valve curved at base, with central spine that is variable in length ( Figs 4D, E , 5I, K, L, N ). Secondary valve smaller and easily overlooked ( Figs 4D, E , 5I, K, L, O ). Main valve connected to inconspicuous junctional membrane ( Fig. 5I ).

Oral cilia approximately 18 μm long. Haplokinety and polykinety commencing together to form a spiral that performs about 1.5 turns around peristomial disc before plunging into infundibulum where they perform a further turn ( Figs 4H, I , 5Q–T ). Within infundibulum, haplo- and polykineties spiral on opposite walls, terminating at cytostome. The polykinety transforms into three infundibular polykineties (P1–3), each consisting of three parallel rows of kinetosomes ( Figs 4L, M , 5S, T ). All rows of P1 are equally long ( Figs 4I , 5S, T ). Three rows of P 2 in a staggered arrangement, that is, row 1 commences slightly behind P1 and terminates just before second turn of P1; row 2 starts and ends a little behind row 1; the abstomal end of row 3 starts away from row 2 while the adstomal end terminates beyond row 2 ( Figs 4I , 5S, T ). Row 1 of P3 commences at the middle of P2 and approximately twice as long as the other two rows; adstomal ends of these three rows disordered ( Figs 4I , 5S, T ). Epistomial membrane 1 located near the entrance of infundibulum ( Fig. 4I ). Epistomial membrane 2 ahead of polykinety and haplokinety ( Figs 4I , 5S, T ). Trochal band in mid-region of zooid ( Figs 4C, G , 5Q, R ). Germinal kinety parallel to haplokinety and ends at last bend of haplokinety ( Figs 4I , 5S, T ).

Figures

Fig. 4. Morphology and ciliature of Thuricola kellicottiana. (A) Narrow side view of an individual with two zooids. (B) Narrow side view of an individual with single zooid. (C) Wide side view of an individual with single zooid, to show macronucleus in vivo. (D) Narrow side view of lorica. (E) Wide side view of lorica. (F) Detail of pellicle, to show the transverse striations and aboral trochal band. (G) Macronucleus after protargol staining. (H) Model pattern of oral ciliature. (I) Oral ciliature. (J) T. innixa from Kellicottiana, 1884. (K) Thuricolopsis kellicottiana from Stokes, 1887. (L) Cothurnia castellensis from Penard, 1914. (M) T. amphora from Sommer, 1951. (N) T. kellicottiana from Bernerth, 1982. (O) T. kellicottiana from Nusch, 1970. (P) T. kellicottiana from Trueba, 1980. (Q) T. kellicottiana from Shen and Gu (2016). EM1–2, epistomial membrane 1–2; G, germinal kinety; H, haplokinety; JM, junctional membrane; Ma, macronucleus; Po, polyki- nety; P1–3, infundibular polykineties 1–3; Sp, spine; TB: trochal band; Val, valve. Scale bars = 100 μm.

Fig. 5. Photomicrographs of Thuricola kellicottiana in vivo (A–P) and after protargol staining (Q–T). (A–C) Narrow side view of individuals with two zooids (A, B) and single zooid (C). (D) Wide side view of a single zooid individual. (E–G) Narrow side views of different individuals, arrowheads mark contractile vacuoles. (H) Detail of pellicle, to show the transverse striations. (I) Narrow side view of lorica, arrowhead marks the valve spine. (J–L) Wide side view of lorica, arrows mark junctional membrane, arrowheads mark valve spine. (O) Narrow side view of anterior portion of lorica, arrows mark valves, arrowheads marks valve spine. (P) Posterior portion, arrows mark the bulge in the lorica, arrowhead marks junctional membrane around the inner stalk. (Q, R) Ciliature of two specimens, arrowhead marks trochal band. (S) Oral ciliature, arrow marks epistomial membrane 2. (T) Detail of infundibular polykinety 1–3, arrow marks epistomial membrane 2. G, germinal kinety; H, haplokinety; Ma, macronucleus; P1–3, infundibular polykineties 1–3. Scale bars = 100 μm.

Fig. 2. Morphology and ciliature of Thuricola obconica. (A) Narrow side view of an individual with two zooids. (B) Narrow side view of an individual with single zooid. (C) Narrow side view of an individual with single zooid, to show macronucleus. (D) Wide side view of an individual with two zooids. (E) Wide side view of lorica. (F–H) Narrow side view of different curved lorica. (I) Base of lorica. (J) Detail of pellicle, to show the transverse striations and trochal band. (K) Model pattern of oral ciliature. (L) Macronucleus after protargol staining. (M) Oral ciliature. (N) Detail of infundibular polykineties. (O) T. obconica from Kahl (1933). (P) T. obconica from Kahl (1935). (Q) T. obconica from Bock (1952). (R) T. kamptostoma from Bock (1952) (synonym of T. obconica). (S) T. obconica from Biernacka (1963) (pos- sible misidentification). (T) T. obconica from Küsters (1974) (probably misidentified). (U) T. obconica from Shen & Gu (2016). EM1–2, epistomial membrane 1–2; G, germinal kinety; H, haplokinety; JM, junctional membrane; LB, lorica base; Ma, macronucleus; Po, polykin- ety; P1–3, infundibular polykineties 1–3; TB, trochal band; Val, valve. Scale bars = 100 μm (A, B, D); 50 μm (E–H, L, O–U).

Fig. 3. Photomicrographs of Thuricola obconica from life (A–N) and after protargol staining (O–S). (A) Narrow side view of an individual with two zooids. (B) Narrow side view of an individual with single zooid. (C) Wide side view of an individual with two zooids. (D, E) Narrow side view of different individuals. (F–H) Narrow side view of different curved loricas. (I) Anterior portion of body, arrow marks contractile vacuole. (J) Posterior portion, arrowhead marks junctional membrane around the inner stalk. (K) Posterior portion, arrow marks the expanded lorica base, arrowheads mark the junctional membrane. (L) Wide side view of lorica, arrowhead marks the junctional mem- brane. (M) Narrow side view of anterior portion of lorica, arrow marks valve. (N) Detail of pellicle, arrowhead marks aboral trochal band. (O–Q) Ciliature of three specimens, arrow marks trochal band. (R) Oral ciliature, arrow marks the epistomial membrane 2. (S) Detail of infundibular polykineties 1–3. EM1, epistomial membrane 1; G, germinal kinety; H, haplokinety; Ma, macronucleus; P1–3, infundibular polykineties 1–3. Scale bars = 100 μm (A–H); 50 μm (O–Q).