המועדפים של richard_1

Nassulides pictus (Greef, 1888) Foissner, Agatha & Berger 2002 from a rainwater puddle in a neglected lawn. Imaged in Nomarski DIC on Olympus BH2S using SPlanap 40 0.95 objective plus variable phone camera cropping on Samsung Galaxt S9+. The cell measure 80 um in length. The cytoplasm is filled with colorful (mostly green) algae. The cytopharyngeal basket or nasse is plainly visible as are the single mid-cell contractile vacuole and the round macronucleus. Optical sectioning shows the small pellicular mucocysts. There are a few short caudal cilia as depicted by Foissner et al 1994 but not mentioned in the text. The hypostomial frange could not be imaged. A right anterior patch of yellowish granules is visualized.

Nassula is a genus of unicellular ciliates, belonging to the class Nassophorea. Like other members of the class, Nassula possesses a basket-like feeding apparatus (nasse, or cyrtos) made up of cytopharyngeal rods (nematodesmata), which are themselves composed of closely packed microtubules. Nassula use this structure to ingest filamentous cyanobacteria, drawing individual strands of blue-green algae through the cytopharynx and into the body of the cell, where they are digested. As the algae are broken down, they can take on a variety of bright colours, which give Nassula a distinctive, variegated appearance under the microscope. The body is ovoid to elongate, and uniformly ciliated, with a single macronucleus and a partial hypostomial frange (synhymenium) running from the left side of the cell to the oral aperture. When food is scarce, members of the genus have the ability to become dormant by forming a microbial cyst. Excystment can be induced by exposure to a medium inoculated with wild bacteria.

Nassula reproduce asexually, by fission. During reproduction, the cell is divided transversally. As in most ciliates (with the exception of the Karyorelictea) the macronucleus splits, during division, and the micronuclei also undergo mitosis. While fission is an asexual process, it may be preceded by conjugation, during which compatible mating individuals come together and transfer genetic material across a cytoplasmic link. In conjugation, the micronuclei of each cell undergo meiosis, and haploid micronuclei are then exchanged from one cell to the other. After sexual exchange has occurred, both conjugants will divide by fission.

Diagnostic features from Foissner et al (1994):
1) Size in vivo 70-140 x 35-70 um, mostly around 100 um long.
2) Shape clumsy ellipsoid. Slightly flattened ventrally.
3) Macronucleus usually spherical slightly behind the middle of the body. 1 small micronucleus.
4) Contractile vacuole approximately in the middle of the body, surrounded by small auxiliary vacuoles.
5) Extrusomes (mucocysts; no rod-shaped trichocysts) barely recognizable, according to methyl green. However, when stained with pyronin they form a thick shell. Cells through many close food vacuoles with cyanobacteria and algae in various stages of digestion are strikingly colorful.
6) Approximately 37-50 longitudinal ciliary rows. Few elongated caudal cilia (depicted but not described in text).

7) Mouth funnel (nasse/cyrtos) in the front third of the body approximately in the median, without a clear ring made of around 24 strongly twisted bars. Hypostomial cilia band (synhymenium) straight, consisting of 7-8 tufts arranged obliquely to the somatic rows of eyelashes.

Because of the mostly colorful coloring and the striking nasse it is easily recognizable as a nassulid ciliate. Following species have a similar size and shape (FOISSNER 1989): Nassula tumida MASKELL (contractile vacuole clearly behind the middle of the body, described superficially); N. terricola FOISSNER (8-10 hypostomial cilia tufts; hypostomial cilia band sigmoid; cyst with bar-like protrusions jumps, whereas in N. picta it is smooth; N. vernalis GELEI & SZABADOS (with fusiform,easily recognizable trichocysts, 40-50 very fine nasse rods); N. citrea KAHL (with spindle-shaped, easily recognizable trichocysts, 34-38 nasse rods; Re-description in EISLER 1986); Obertumia gracilis FOISSNER and O. Kahli FOISSNER (hypostomial cilia band divided into two, about 16 Reuscythe sticks). From Nassula ornata (155-320 um, with spindle-shaped, easily recognizable trichocysts) and Obertrumia aurea (around 200 um) easily distinguished by their much smaller size. The separation from the sometimes colorful -+ Holophrya species is best done by the location of the nasse (more delicate and apical in Holophrya) and the contractile vacuole (in the posterior end in Holophrya). Features 1, 5, 7 are particularly important for identification.

Nassulides nov. gen. Diagnosis: Nassulid organelles numerous, rightmost ones orientated obliquely to frange axis and overlapping proximally, others arranged parallel to frange axis. Type species: Nassula picta Greef, 1888. Etymology: Composite of Nassula (nassa; lat., basket) and ides (gr., similar to genus
Nas sula). Masculine gender.
Systematic position and comparison with related genera: Nassulides has a nassulid frange which commences underneath the oral opening, extends across the left ventral side, and terminates dorsally. Accordingly, it belongs to the family Nassulidae, as defined above. Nassulides is rather similar to Nassula, differing solely by the oblique arrangement of the right nassulid organelles. Thus, its generic status might be questioned. On the other hand, nassulids are a species-rich group requiring some organization for practical purposes. The following species have to be combined with Nassulides: N. pictus (Greef, 1888) nov. comb. (basinoym: Nassula picta).....(2).

1. Wilhelm Foissner, Helmut Berger, and Fritz Kohmann; [Taxonomische und okologische Revision der Ciliaten des Saprobiensystems-Band III: Hymenostomata, Prostomatida, Nassulida]. Informationsberichte des Bayerisches Landesamt fur Wasserwirtschaft. (1/94): pp 445-50 1994
2. FOISSNER W., AGATHA S. & BERGER H. (2002): Soil ciliates (Protozoa, Ciliophora) from Namibia (Southwest Africa), with emphasis on two contrasting environments, the Etosha region and the Namib Desert. – Denisia, 5: 1–1459.

Fly Pirates rob Droptail Ants

Two days ago I was surprised to see flies of the genus Bengalia robbing false army ants of their larvae. Then I noticed that wherever there were ants of any species collecting food, there were Fly Pirates in attendance. The flies were robbing ants of whatever they picked up: Bits of flowers, seeds, or any organic material. Since there seemed to be an abundance of such snacks lying around on the forest floor, I started wondering why the flies couldn't simply gather their own food. Perhaps the flies saved labour by letting the ants discern edible stuff from the rest. So I ran a little experiment. What if I presented the flies with something that was obviously a good meal, like grated cheese?

So I placed some cheese within view/smell of the flies. No reaction!
In no time at all some droptail ants started breaking up the cheese gratings for easier transport back to their nest. The flies observed but kept their distance.

OBSERVATION: The flies ONLY become interested once the ants start carrying the cheese cuttings.
Before that, the flies observed the ants intently. At one stage a fly perched atop a passing duo of Toktokkies (busy trying to sort out their reproductive plumbing), enjoying a touring view of the feasting place. There were ample bits of cheese unattended, close to the flies, but their interest was focused only on the ants. Once an ant started moving a piece of cheese, a fly or two would start harassing it. Sometimes a tug of war ensued and sometimes the ant would let go and charge the fly, which then retreated. On some occasions the fly would take the fight into the air, gripping the cheese with its forelegs trying to shake the ants off. If that failed, it would drop the ant and cheese quite violently to the ground and then try and separate cheese from ant. On some occasions the fly would simply start feeding on a chunk of cheese while the ant was underway, not trying to separate it from the ant. The irritated ant would then drop the cheese and shoo the fly away (see gif animation).

What struck me was that the flies treated the droptails with less respect than the false army ants. The droptails have stingers, no? The false army ants have no stingers and are blind, but seem to have powerful mandibles and are quick movers.