Drepanomonas multidentata Foissner & Omar nov., 2014

Omar, Atef & Foissner, Wilhelm, 2014, Three New Microthoracids (Ciliophora, Nassophorea) from Austria and Venezuela, Acta Protozoologica 53 (4), pp. 295-311 : 299-308

Drepanomonas multidentata Foissner & Omar nov.

spec. ( Figs 16–21 , 25–40 ; Table 1)

Diagnosis: Size in vivo about 45 × 25 µm. Body crescentic with acute ends made by ground cortex. Three conspicuous spines in mid-body: one right and anterior of oral opening, two on a convexity at level and posterior of oral opening. Right side with an elevated obfalcate plate between kineties 2 and 3; ridge associated with kinety 3 ends in a subapical spine. Left side with a ridge each along kineties 5 and 6 both forming a spine anteriorly and a tridentate pattern posteriorly. Somatic kinety 4 commences with a dikinetid followed by six monokinetids; kineties 6 and 7 only partially ciliated. On average a total of 107 basal bodies. Extrusomes absent.

Type locality: Slightly saline surface mud and soil from temporary grassland puddles in the surroundings of the village of Chichiriviche, Maracay National Park, about 13 km inshore from the north coast of Venezuela, 11°33′N, 67°13′W .

Type material: One holotype slide with protargol-impregnated specimens and five paratype slides with protargol-impregnated and Klein-Foissner silver nitrate-impregnated specimens have been deposited in the Biology Centre of the Museum of Upper Austria, Linz (LI). The holotype and important paratype specimens have been marked by black ink circles on the coverslip .

Etymology: the species name is a composite of the Latin prefix multi (many) and the Latin adjective dentata (toothed), referring to the multitude of body teeth.

Description: Depending on method, body size varies considerably ( Table 1): in vivo about 47 × 27 µm (n = 4), in Klein-Foissner silver nitrate preparations 43 × 25 µm, while cells shrank to 35.5 × 16.8 µm in protargol slides. Taking into account the in vivo measurements and 5% shrinkage in the silver nitrate preparations, we obtain an in vivo size of 40–50 × 20–30 µm, on average about 45 × 25 µm, corresponding to a length: width ratio of 1.9, which matches values obtained from 17 specimens photographed alive ( Figs 25–27, 29–36 ); protargol-impregnated cells have a ratio of 2.1 and are thus slightly more slender ( Table 1; Figs 37, 38 ).

Body crescentic with acute ends and several ventral and lateral spines; laterally only slightly flattened, except for thin dorsal margin; when observed ventrally or dorsally, slenderly elliptical with left side slightly more convex than right side ( Table 1; Figs 16–20 , 25, 30 , 36, 39 ).

Nuclear apparatus in or near mid-body. Macronucleus globular to broadly ellipsoidal, contains some globular masses, probably nucleoli up to 2 µm across. Micronucleus globular, near or attached to ventral side of macronucleus ( Table 1; Figs 16, 19 , 30 , 37 ). Contractile vacuole in third quarter of body, slightly posterior and dorsal of buccal cavity, with distinct tube extending into buccal cavity posterior to adoral membranelles ( Table 1; and 7–9 shortened anteriorly and/or posteriorly. Kineties 1–4 on right side; kineties 5–7 on left side; and kineties 1, 2 and 6–9 on ventral side ( Table 1; Figs 16–20 , 37–40 ).

Oral apparatus in mid-body ( Table 1; Figs 16, 18, 20 , 31 , 37, 39 ). Buccal cavity deep contains two or three adoral membranelles. Membranelle 1 distinctly smaller than membranelles 2 and 3, recognizable only in dividers ( Fig. 21 ); membranelles 2 and 3 obliquely arranged to main body axis and so close together that details cannot be recognized. Nasse kinetosomes anterior to adoral membranelles ( Figs 20 , 39 ); oral basket not recognizable.

Occurrence and ecology: As yet found only at type locality (see above). It grew well in a raw culture with tap water to which were added three squashed wheat grains and a few ml of the soil eluate from the non-flooded Petri dish culture.

Comparison of Drepanomonas multidentata with similar species: Using the species characteristics for Drepanomonas suggested by Omar and Foissner (2013), D. multidentata is unique by the three ventrolateral spines, the tridentate spine pattern in the posterior half of the left side, and the absence of extrusomes. Similar species are D. dentata Fresenius, 1858 , D. lunaris Foissner, 1979 , and D. obtusa Penard, 1922 , all having extrusomes. Further, D. dentata differs from D. multidentata not only by the spine pattern but also by body size (~ 80 µm vs. 45 × 25) and the serrate (vs. smooth) ventral and dorsal margin ( Kreutz 1998; cp. Figs 22–24 with Figs 16, 17 ). Drepanomonas lunaris and D. obtusa differ from D. multidentata not only by the spine pattern but also by the rounded and truncated (vs. acute) posterior body end, respectively.

Figures

Figs 16–24. Drepanomonas multidentata (16–21) and D. dentata (22–24) from life (16, 17, 22–24) and after protargol impregnation (18–21). 16, 17 – right and left side view of a representative specimen, length 45 µm, showing the crescentic body and the cortical ridges. The right side ridges form an obfalcate plate with a subapical spine and a shallow concavity in the posterior portion (asterisk); the two left side ridges, each with a spine anteriorly, produce a tridentate pattern posteriorly. Note the three highly characteristic ventro-lateral spines in the surrounding of the oral opening. 18, 19 – right and left side view of holotype specimen, length 35 µm, showing the kinetid pattern and the nuclear apparatus; 20 – ventral view of a paratype specimen, showing the obliquely arranged preoral kineties, the circumoral basal bodies, and the postoral complex. The posterior segment of somatic kinety 1 cannot be seen in this specimen because it is over the deeply impregnated macronucleus (outline dotted); 21 – in dividing specimens, three adoral membranelles are recognizable both in proter and opisthe. The arrowheads mark the ventro-lateral spines; 22–24 – D. dentata (22, 23, from Fresenius 1858; 24, from Kreutz 1998), showing the crescentic body, the tooth-like projection on the ventral side (triangle), the serrate dorsal (arrows) and ventral (arrowhead) margin, and the cortical ridges.A – anterior body end, K(1–9) – somatic kineties, LAS – left anterior spines, LVS – left ventro-lateral spines, M(1–3) – adoral membranelles, MA – macronucleus, MI – micronucleus, NK – nasse kinetosomes, P – posterior body end, PC – postoral complex, PO(1–3) – preoral kineties, R – ridges, RVS – right ventro-lateral spine, SAS – subapical spine, T – excretory tube of contractile vacuole, TP – spines of the tridentate pattern. Scale bars: 10 µm.

Figs 25–32. Drepanomonas multidentata from life under bright field (25–27) and interference contrast illumination (29–32), and after silver nitrate impregnation (28). 25, 26 – right and left side view of the same specimen, showing the crescentic body shape and the three ventrolateral spines. The cytoplasm is studded with lipid (?) droplets and minute food vacuoles each containing only one or two bacteria (26). The arrows mark the line where the cortical plates of the right side attach to the ground cortex. The arrowhead denotes the left margin of the preoral region; 27 – right side view of a dividing specimen with division furrow marked by arrowheads; 28 – right side view, showing the dense cortical granulation and the ventro-lateral spines; 29–32 – right side views of the same specimen at four focal planes, showing the right side ridges (29), the subapical and the right ventro-lateral spine (30), the buccal cavity in mid-body (31), and the spines of the left ventro-lateral side (32). The arrowhead marks the concave right ventro-lateral margin. The asterisk denotes the shallow concavity in the obfalcate plate.A – anterior body end, BC – buccal cavity, CV – contractile vacuole, CY – cytopyge, FV – food vacuoles, K3 – somatic kinety 3, LAS – left anterior spine, LD – lipid droplets, LVS – left ventro-lateral spines, MA – macronucleus, P – posterior body end, PO – preoral kineties, R – ridges, RVS – right ventro-lateral spine, SAS – subapical spine, T – excretory tube of contractile vacuole, VS – ventro-lateral spines. Scale bars: 15 µm.

Figs 33–40. Drepanomonas multidentata from life (33–36) and after protargol impregnation (37–40). 33–36 – left side views of different specimens at four focal planes, showing the two conspicuous spines left and posterior of the oral opening, the left side ridges each forming an anterior spine, and the two anterior spines of the tridentate pattern; 37, 38 – right and left side view of holotype and of a paratype specimen, showing the ciliary and nuclear pattern. The posterior portion of kinety 9 is either absent or in line with kinety 2. The posterior cilium of kinety 6 appears slightly thickened in the basal portion (arrowhead); 39 – ventral view of a paratype specimen, showing the oblique preoral kineties and the postoral complex; 40 – ventral view of a late divider, showing that kineties 8 and 9 consist of two and three segments, respectively, of which the posterior segment of kinety 9 will possibly align with kinety 2 (see Fig. 37). The left segment of the postoral complex consists of four ciliated monokinetids. A – anterior body end, K1–9 – somatic kineties, LAS – left anterior spines, LVS – left ventro-lateral spines, M – adoral membranelles, MA – macronucleus, MI – micronucleus, NK – nasse kinetosomes, PC – postoral complex, PO(1–3) – preoral kineties, R – ridges, T – excretory tube, TP – spines of the tridentate pattern. Scale bars: 15 µm (Figs 33–36) and 10 µm (Figs 37–40).