Hartmannula derouxi, Gong & Song, 2004

Gong, Jun & Song, Weibo, 2004, Morphology and infraciliature of two marine species of Hartmannula (Protozoa, Ciliophora, Cyrtophorida), from scallop-farming waters off Qingdao (Tsingtao), China, Journal of Natural History 38 (11), pp. 1327-1337 : 1329-1334

Hartmannula derouxi nov. spec.

( figures 1–9 , 14–23 ; tables 1, 2)

Diagnosis. Marine Hartmannula , in vivo 60–120X 30–70 µm, body long oval to elongate in outline, pellicle covered with a smooth, thin layer of gel-like substance; 42–53 ventral kineties, the rightmost 11–12 of which extend apically; about 30 nematodesmata; about 25 ventrally located contractile vacuoles.

Type deposition. One holotype slide of protargol impregnated specimens is deposited in the Natural History Museum , London (registration number 2003:7:23:1). Two paratypes are deposited in the Laboratory of Protozoology, Ocean University of China, People’s Republic of China (number HD 2001-12-22) .

Dedication. We dedicate this new species to Dr Gilbert Deroux, the outstanding French protozoologist, in recognition of his great contribution in ciliatology.

Description. Cell size 60–120X 30–70 µm in vivo, body shape usually long oval to elongate in outline, but highly flexible: in large individuals posterior 75–80% of body length often swollen due to ingested algae; flat in some small individuals ( figures 2, 3 ). Right margin more convex than left, with pronounced anterior ‘beak’ to left ( figures 1, 6 , 14–17 ); usually ventral surface flat, dorsal surface convex. Single arched transversely orientated groove on dorsal side near the anterior end ( figure 15 , double-arrowheads). Pellicle relatively thick, covered with smooth, thin, colourless layer of gel-like substance ( figure 1 , 15 , arrows). Cytostome slitlike, ca 20X 10 µm in size in vivo, surrounded by 30 straight nematodesmata (see table 1), each of which is tipped with one tooth and ca 15 µm in length, extending slightly leftwards and posteriorly. Endoplasm turbid, greyish to dark when overfed, filled with numerous food granules, and algae frequently observed in large individuals. Cilia about 8–10 µm long. Many contractile vacuoles, about 2–3 µm in diameter, irregularly distributed on ventral side ( figures 1 , 14, 16 ); over 20 contractile vacuole pores recognized after protargol and silver nitrate impregnations ( figures 5 , 21, 22 ). Podite about 20 µm in length, located left-posteriorly, secreting glue-like substance for adhering to substratum ( figures 1 , 17 ). Movement slow, frequently bending to left and swirling backwards thus making body turn around by certain angle when crawling over substrata.

Infraciliature as shown in figures 4, 7, 8 , 18–20 ; 42–53 somatic kineties, the rightmost 11–12 of which extend apically (frontoventral kineties, table 1); oral field divides these kineties into three parts: 12–19 kineties (right kineties) positioned to right of oral area, extending posteriorly to vicinity of podite; 18–19 left and 10–15 suboral kineties; left and suboral kineties progressively shortened at their posterior ends from right to left ( figures 4, 7 ). Terminal fragment comprising 15–21 basal bodies ( figure 8 , arrow; figure 20 , arrowheads); equatorial fragment usually present, composed of about 15 basal bodies ( figure 4 , arrowhead). About 13 kinetosome-like dots present near base of podite ( figure 4 , arrow). Macronucleus ellipsoidal, heteromerous, about 24X 12 µm ( figure 4 , double-arrowheads; figure 19 , arrowhead). Micronucleus not detected.

Three oral kineties typical of genus: two circumoral kineties (outer and inner) anterior of cytostome and one preoral kinety left of them, all arranged almost in direction of suture line. The outer circumoral kinety with ca 34 pairs of basal bodies, longer than the inner, which contains ca 20 pairs. Preoral kinety comprising ca 17 basal body pairs, anterior and right of circumoral kineties ( figures 7 , 19 , arrow, table 1).

Silverline system irregularly reticulate with several tiny argentophilic granules on or near silverlines ( figures 9 , 23 ).

Comparison

Of the four known Hartmannula species, only three of them, i.e. H. acrobates , H. angustipilosa and H. oliva , have been studied using silver impregnations ( Dragesco, 1966; Deroux and Dragesco, 1968). Since the infraciliature of H. oliva exhibits a distinct glabrous area, which is completely surrounded by kinetosomes and where the podite is positioned, Deroux (1974) established a new genus, Aegyriana , for this species, A. oliva Deroux, 1974 . Therefore, only three species reside in the genus Hartmannula and should be compared with our new species.

Hartmannula derouxi nov. spec. can be distinguished from H. angustipilosa Deroux and Dragesco, 1968 in terms of its: (1) body size in vivo (60–120X30–70 versus 40–80X20–50); (2) number of somatic kineties (42–53 versus 20–28); (3) number and position of contractile vacuoles (over 20 in number, irregularly distributed on ventral side versus four to seven, arranged in a longitudinal row) ( table 2).

Morphologically, Hartmannula acrobates Poche, 1913 is similar to H. derouxi nov. spec. in terms of body shape, size, habitat and basic pattern of infraciliature ( table 2). Nevertheless, the original description (as Onychodactylus acrobates Entz, 1884 ) and the subsequent redescriptions ( Schouteden, 1906; Dragesco, 1966; Jones, 1974) consistently indicate that H. acrobates has only one contractile vacuole which is positioned to the right of the mid-body (versus many contractile vacuoles, irregularly distributed on ventral side in H. derouxi ), thus it can be distinctly separated from our new species.

The infraciliature of Hartmannula entzi Kahl, 1931 has yet to be described. It differs however, from our new species in living features: according to the original (as Aegyria oliva by Entz, 1884) and subsequent redescriptions ( Wang, 1934; Carey, 1992), this species consistently exhibits a wide, slit-like and transversely positioned cytostome (versus longitudinally situated along the long axis of cell in H. derouxi ), and ca three contractile vacuoles (versus over 20 in H. derouxi ).

Hartmannula angustipilosa Deroux and Dragesco, 1968 ( figures 10–13 , 24–31 ; tables 1, 2)

Improved diagnosis. Marine Hartmannula , in vivo 40–80X 20–50 µm, body oval in outline; 20–28 ventral kineties, the right five to six of which extend apically; four to seven contractile vacuoles arranged in a longitudinal row on right side of cell.

Description of Qingdao population. Cell size in vivo 40–60X 20–30 µm, and oval in outline shape, with anterior and posterior margins rounded, anterior ‘beak’ projected to left ( figures 10, 11 , 24 ); dorsoventrally about 1:3 flattened. Ventral surface flat, while dorsally vaulted. Cyrtos consisting of about 10 toothed nematodesmata, 15 µm long, tapering posteriorly. Endoplasm greyish, with numerous small granules (ca 1–4 µm in diameter), ingested algae also frequently observed. Macronucleus oval, centrally positioned, ca 12 µm in diameter. Cilia 5 µm long. Podite small, about 6 µm in length, located almost central near posterior end ( figure 10 ). Ventral surface around podite usually twisted, and probably plays a role in attachment. Four to seven contractile vacuoles, about 3 µm in diameter, longitudinally arranged on right ( figures 10 , 24, 25 ); contractile vacuole pores can be recognized after impregnation between kinety 7 and 8 (excluding equatorial fragment) from right (among six, seven and eight in one specimen, N ~ 6; figures 12 , 27–30 ). Movement moderately fast, crawling or sliding over substrata.

Infraciliature as shown in figures 12, 13 , 26 . Ventral kineties in 24–28 rows. Five to six kineties extending apically, bending around and reaching left kineties at the beak-like projection; 10–12 suboral and 8–11 left kineties. Six to 11 kinetosome-like dots present near base of podite. Terminal and equatorial fragments with five to seven and zero to nine basal bodies, respectively. Macronucleus oval, about 12X 7 µm in size ( table 1). Micronucleus not detected.

Arrangement of three oral kineties typical of genus and considerably shorter than those in Hartmannula derouxi : with 14–19, seven to eight and 8–12 pairs of basal bodies in outer, inner and preoral kineties, respectively ( table 1).

Silverline system irregularly reticulate as in Hartmannula derouxi ( figures 13 , 31 ). Remarks

In the original description of Hartmannula angustipilosa , no information on the number of contractile vacuoles is given ( Deroux and Dragesco, 1968). Several years later, Agamaliev (1974) redescribed a Caspian population with seven contractile vacuole pores. He stated, incorrectly however, that the contractile vacuole pores were located on the dorsal side. The Qingdao population demonstrates that the number of contractile vacuoles is not constant (ranging from four to seven; see table 2), and also that contractile vacuole pores are consistently located on the ventral side (always in a longitudinal row on the right).

Figures

FIGS. 1–9. Morphology and infraciliature of Hartmannula derouxi nov. spec. from life (1–3, 6), after protargol (4, 7, 8) and silver nitrate impregnation (5, 9). (1) Ventral view of a typical individual, arrow indicates gel-like substance. (2) Dorsal and lateral views of a well-fed specimen. (3) Dorsal and lateral view of a small individual. (4) Infraciliature, showing equatorial fragment (arrowhead), macronucleus (double-arrowheads) and podite (arrow). (5) Ventral view, showing the arrangement of contractile vacuole pores. (6) Dorsal view. (7) Infraciliature of oral field; (8) Dorsal view of anterior portion, arrow marks terminal fragment. (9) Silverline system on dorsal side. Co, circumoral kineties; CVP, contractile vacuole pores; FvK, frontoventral kineties; LK, left kineties; Pr, preoral kinety; RK, right kineties; SoK, suboral kineties. Bars: 40µm (1, 4, 7, 9); 60 µm (2, 3).

FIGS. 14–23. Photomicrographs of Hartmannula derouxi nov. spec. from life (14–17), after protargol (18–20) and silver nitrate impregnation (21–23). (14) Ventral view, arrowheads indicate contractile vacuoles in anterior portion. (15) Dorsal view, showing the gel-like layer on the cell surface (arrow), macronucleus (arrowhead) and arched recess (double-arrowheads). (16) Ventral view, focusing on cytostome (arrow) and several contractile vacuoles in posterior portion (arrowheads). (17) Showing the podite (arrow). (18) Ventral view of infraciliature. (19) Infraciliature of anterior portion, note the preoral kinety (arrow), cytostome (double-arrowheads) and macronucleus (arrowhead). (20) Showing the terminal fragment (arrowheads). (21) Focusing on contractile vacuole pores on the right of ventral surface (arrows). (22) Ventral view, arrows indicate the contractile vacuole pores on the left of ventral surface. (23) Silverline system on dorsal side. Bars: 50 µm (14–17); 40 µm (18); 20 µm (19–22); 10 µm (23).

FIGS. 10–13. Morphology and infraciliature of Hartmannula angustipilosa from life (10, 11), after protargol (13) and silver nitrate impregnation (12). (10) Ventral view. (11) Dorsal view. (12) Silverline system on ventral side, arrows indicating contractile vacuole pores. (13) Ventral view, showing general appearance of infraciliature. P, podite. Bars: 30 µm.

FIGS. 24–31. Photomicrographs of Hartmannula angustipilosa from life (24, 25), after protargol (26) and silver nitrate impregnation (27–31). (24, 25) Dorsal (24) and ventral (25) views, arrows indicate contractile vacuoles. (26) Ventral view to indicate the kinetosome-like dots (arrow), macronucleus (double-arrowheads) and an ingested diatom (arrowhead). (27, 29) Ventral view of two specimens, arrows mark the contractile vacuole pores. (28, 30) Right-ventral view of two specimens,showing the position of contractilevacuole pores (arrows). (31) Silverline system on dorsal side. Bars: 20 µm.