Leptopharynx lajacola Omar & Foissner, 2014

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

Leptopharynx lajacola Omar & Foissner nov. spec.

( Figs 41–47 ; Table 1)

Diagnosis: Size about 32 × 17 µm in protargol preparations. Body outline quadrangular to elliptical with flat to slightly convex dorsal side, flat ventral side and slightly oblique preoral region, body ends broadly rounded. Ten somatic kineties and a postoral complex generated by kineties 9 and 10; kineties 1 and 2 with dikinetids anteriorly; kinety 6 composed of four monokinetids; kinety 10 far posterior of adoral membranelles and without dikinetids; preoral kineties on ventral side. On average 143 basal bodies. Three adoral membranelles, membranelles 2 and 3 form a flat, quadrangular ciliary field. Oral basket about 3 µm wide, strongly convex with opening directed posteriorly. Oral primordium left of kinety 1.

Type locality: Soil, mud, and moss from ephemeral puddles (Lajas) with Velosiacean plants in the surroundings of the farm of Mr. Eisenberg, outskirts of the town of Puerto Ayacucho, Venezuela, 5°40′N, 67°35′W .

Type material: One holotype and two paratype slides with protargol-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: Composite of Laja, the Venezuelan word for ephemeral puddles on granitic outcroppings, and the Latin verb colere (to dwell), referring to its habitat.

Description: This species was overlooked in the raw sample where it was much rarer than the common L. costatus . Thus, all observations are from protargol-impregnated specimens. Fortunately, L. lajacola has some outstanding features which are well recognizable in protargol preparations, viz., the quadrangular body shape, the lack of dikinetids in kinety 3, and the strongly curved oral basket whose opening is directed posteriorly. Thus, this species should be recognizable also without in vivo data.

Assuming 15% preparation shrinkage, L. lajacola should have an in vivo size of 30–40 × 15–22 µm, on average about 35 × 18 µm ( Table 2); length: width ratio 1.7–2.1:1, on average 1.9:1; laterally flattened about 2:1, both sides slightly convex. Body usually conspicuously quadrangular with both ends broadly rounded, anteriorly slightly narrower than posteriorly due to the slightly receding preoral region ( Figs 41–43 , 45–47). Nuclear apparatus in or near body centre, usually in curve formed by oral basket. Macronucleus globular, contains minute, argyrophilic masses, probably nucleoli. Micronucleus globular, usually attached to ventral side macronucleus ( Table 2; Figs 42 , 45–47). Opening of contractile vacuole in third quarter of ventral side, i.e., right of posterior part of oral primordium, tube composed of fibres forming a star-like pattern at tube base ( Table 2; Figs 41 , 45). Cytopyge slightly posterior to contractile vacuole, extends between posterior portions of kineties 2 and 10, in protargol preparations usually marked by a short, thick line ( Fig. 45). Extrusomes lenticular, 4–5 µm long. Cytoplasm with few to many lipid (?) droplets 0.5–3 µm across ( Fig. 45).

Cortex comparatively smooth, similar to that of L. costatus , margin of kineties 1, 4 and 5 distinctly impregnated. Ventral side with conspicuous preoral furrows and a shallow concavity containing oral basket opening and adoral membranelles ( Figs 41–47 ).

Cilia 6–8 µm long, arranged in 10 somatic and three preoral rows (kineties), each showing a specific number and pattern of basal bodies; on average a total of 143 kinetids ( Table 2). Kineties 2–5 and 7 bipolar, kineties 1, 6 and 8–10 shortened anteriorly and/or posteriorly. Kineties 1–4 on right side, kineties 5–8 on left side, kineties 9 and 10 on ventral side ( Table 2; Figs 41, 42, 44 , 45–47).

Kinety 1 extends along right margin of oral field, ends slightly posterior of mid-body; composed of seven narrowly spaced, ciliated dikinetids and a single monokinetid at posterior end; posterior dikinetid and monokinetid usually slightly dislocated to the left ( Figs 41, 44 , 45). Kinety 2 composed of two widely spaced, ciliated dikinetids anteriorly, followed by 7–9 widely spaced, ciliated monokinetids leaving a more or less wide break in middle third of row ( Figs 41 , 45). Kinety 3 composed of widely spaced, ciliated monokinetids throughout, a single kinetid-wide break in mid of row ( Fig. 45); begins with two dikinetids anteriorly in one out of 21 specimens. Kineties 4 and 5 limit dorsal margin of right and left body side, composed of moderately narrowly and widely spaced, ciliated monokinetids throughout, respectively ( Figs 41, 42 , 45–47). Kinety 6 composed of two narrowly spaced, oblique, non-ciliated monokinetids near anterior end of cell and two widely spaced, ciliated monokinetids in middle body third ( Figs 42 , 46, 47). Kinety 7 composed of widely spaced, likely ciliated monokinetids, forming more or less distinct pairs in anterior half ( Figs 42 , 46, 47). Kinety 8 begins in second quarter of body and consists of three widely spaced, ciliated monokinetids ( Figs 42 , 46, 47). Kinety 9 consists of two segments ( Figs 41 , 45): anterior segment composed of four ciliated dikinetids posterior of preoral kineties; posterior segment posterior to adoral membranelles and composed of a short row of narrowly spaced, ciliated monokinetids (see postoral complex). Kinety 10 consists of three segments ( Figs 41 , 45–47): anterior segment composed of two dikinetids left of adoral membranelles; middle segment composed of three barren, oblique dikinetids posterior to adoral membranelles; posterior segment composed of 4–5 widely spaced, ciliated monokinetids.

Three preoral kineties each composed of ciliated dikinetids and a ciliated monokinetid posteriorly, occupy preoral ventral side and extend obliquely to left side ( Table 2; Figs 41, 43 , 45). Postoral complex similar to that of L. costatus , i.e., composed of posterior portion of kinety 9 and middle portion of kinety 10 ( Table 2; Figs 41 , 45–47). Posterior of rear portion of kinety 9 a single monokinetid possibly belonging to preoral kinety 3, as in L. costatus ( Figs 41 , 45).

Oral apparatus slightly anterior to mid-body within a concave area containing the adoral membranelles; composed of a distinct basket made of nematodesmata, three adoral membranelles, and a paroral (not shown) made of a single row of basal bodies (“nasse kinetosomes”) subapically connected with the basket rods ( Table 2; Figs 41–43 , 45–47). Adoral membranelles obliquely arranged to main body axis and left of oral basket, membranellar cilia form posteriorly directed bundles up to 8 µm long in protargol preparations ( Fig. 47). Adoral membranelle 1 anterior of membranelles 2 and 3 and composed of few, possibly four densely spaced basal bodies. Membranelles 2 and 3 very close together, forming a flat quadrangular field composed of 6 basal body rows, each consisting of an average of four basal bodies; right row possibly barren ( Table 2; Figs 41 , 45, 47). Left of M2 a very short row of basal bodies belonging to the postoral complex and kinety 10 ( Fig. 41 ). Oral basket about 3 µm wide, of unique shape, i.e., strongly convex with basket opening directed posteriorly and in second quarter of cell, abruptly narrowed when turning posteriorly ( Table 2; Figs 41–43 , 45–47). Nasse kinetosomes difficult to recognize, unciliated. Oral primordium composed of two groups of basal bodies: anterior group right of oral basket, barren, usually faintly impregnated and thus difficult to recognize, composed of four to six basal bodies forming a short, slightly convex row; posterior group composed of two minute rows of ciliated dikinetids left of posterior region of somatic kinety 1, left row usually made by a single dikinetid ( Table 2; Figs 41 , 45).

Occurrence and ecology: As yet found only at type locality.

Comparison of Leptopharynx lajacola with similar species: This species has a clear identity and is easily recognized by the strongly convex oral basket whose opening is near mid-body and directed posteriorly. Further characters are the quadrangular body shape and the absence of dikinetids in somatic kinety 3; the last feature is shared with the microstome morph of L. costatus gonohymen Foissner and Omar in Omar and Foissner (2012a) and L. bromelicola Foissner et al., 2011 .

Acknowledgement. Supported by the Austrian Science Fund (FWF project P22846-B17). The technical assistance of Dr. Barbara Harl, Robert Schörghofer, and Andreas Zankl is greatly appreciated.

REFERENCES

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Received on 23 rd September, 2013; revised on 3 rd December, 2013; accepted on 20 th December, 2013

Figures

Figs 41–44. Leptopharynx lajacola after protargol impregnation. 41, 42 – right and left side view of holotype specimen, length 31 µm, showing the quadrangular body shape, the kinetid and nuclear pattern, and the arrangement of the basal bodies on ventral side. Note the narrow, strongly convex oral basket and the three oblique adoral membranelles. The arrow marks the slightly dislocated posterior end of kinety 1. The arrowhead denotes the anterior portion of the oral primordium. Kineties 3 and 4 consist of monokinetids throughout. Kinety 6 consists of four monokinetids; 43 – left side view of a paratype specimen, showing the quadrangular body shape and the narrow, strongly curved oral basket. 44 – transverse section posterior of adoral membranelles (semi-schematic). B – oral basket, K1–10 – somatic kineties, M1–3 – adoral membranelles, MA – macronucleus, MI – micronucleus, OP – oral primordium, PC – postoral complex, PO(1–3) – preoral kineties, T – excretory tube of contractile vacuole. Scale bars: 10 µm.