Carpediemonas

Carpediemonas Ekebom, Patterson & Vors, 1996 (ref. ID; 4872 original paper: Protista Incertae sedis)

[ref. ID; 4872]
Diagnosis; Biflagellated protists of unknown affinities. With ventral groove. Flagella unequal, the anterior flagellum beats with greater excursion, recurrent flagellum long and may have a shallow beat except near its insertion. Moving by skidding, but may attach to substrate by tip of posterior flagellum. (ref. ID; 4872)
Type genus; Carpediemonas membranifera (Larsen & Patterson, 1990) Ekebom, Patterson & Vors, 1996 (ref. ID; 4872)

[ref. ID; 5694]
Circumscription; Cell with two flagella arising at the head of a ventral groove, heterotrophs, and free-living. Mostly from anoxic or organically enriched sites. (ref. ID; 5694)
Ultrastructural identity; Amitocondriate, with two flagella and with three associated basal bodies, giving rise to three major microtubular roots, two of which support the margins of the ventral groove with associated nonmicrotubular material. Recurrent flagellum with three vanes. No extrusomes, no discrete ingestion apparatus but with dictyosomes. (ref. ID; 5694)
Synapomorphy; Excavate flagellates with three basal bodies. (ref. ID; 5694)
Composition; One species has been named (Carpediemonas membranifera); contains second species yet to be named. (ref. ID; 5694)
References; Ekebom et al. 1996; Simpson and Patterson 1999. (ref. ID; 5694)

  1. Carpediemonas membranifera (Larsen & Patterson, 1990) Ekebom, Patterson & Vors, 1996 (ref. ID; 4872 original paper: Protista Incertae sedis) reported author and year? (ref. ID; 4980)
    Basionym; Percolomonas membranifera (Larsen & Patterson, 1990) (ref. ID; 4872)

Carpediemonas membranifera (Larsen & Patterson, 1990) Ekebom, Patterson & Vors, 1996 (ref. ID; 4872 original paper: Protista Incertae sedis) reported author and year? (ref. ID; 4980)

Basionym

Percolomonas membranifera (Larsen & Patterson, 1990) (ref. ID; 4872)

Descriptions

Cell 5 um long (range 4-7.5 um), obovate or posteriorly pointed, slightly compressed laterally, not rigid. With a longitudinal depression on the ventral side stretching for almost the whole cell length. One margin of the groove is formed of a membranous flange. Usually with two flagella of unequal length which emerge from the anterior end of the ventral groove, but occasionally with three or four flagella. The anterior flagellum is as long as the cell or slightly longer. Acronematic posterior flagellum twice to more than three times cell length. The anterior flagellum has a slow sweeping motion with the distal part of the flagellum bent backwards. The posterior flagellum may vibrate actively but there is little excursion. The greatest activity of the posterior flagellum is in that part located within the groove. The distal region may adhere to substrate or may flex. When feeding on suspended bacteria, body and/or posterior flagellum is attached to substrate, anterior flagellum beating less rapidly than posterior flagellum in an arc of 90 degrees - almost 180 degrees. The cell can skid close to substrate with the anterior flagellum beating in a flicking motion (like dog paddling when slow) and the posterior flagellum trails behind. Small filamentous threads may be emerging from the groove although these may be difficult to see. Common in enriched and slightly anoxic samples where it co-occurs with Cafeteria marsupialis. (ref. ID; 4872)

Remarks

Larsen & Patterson (1990) initially described this species as Percolomonas membranifera. Their operational criteria for assigning this species to Percolomonas were that there may on occasions be four flagella and the presence of a longitudinal groove for trapping food. These is however no incontrovertible evidence given by Larsen & Patterson (1990) that no dividing individuals have more than 2 flagella. The pouch may also produce threads and these are difficult to distinguish from flagella. Having now had the opportunity to observe this species again, we feel that we should regard the species as normally having two flagellum and on this basis it should not longer be assigned to Percolomonas. Ultrastructural work will be required to confirm the identity. The moving membrane observed by Larsen & Patterson (1990) was not observed. Free-living flagellates with two flagella and a ventral groove have been assigned to several genera: Cryptobia (Ruinen, 1938), Jakoba (as Cryptobia in Ruinen 1938; Patterson 1990), Developayella (Tong, 1995), and Cafeteria (Patterson & Zolffel 1991). The greatest similarity is with Developayella, but this, like Cafeteria, is a stramenopile and is drawn forward by an extended anterior flagellum when swimming. Despite great similarity in feeding behaviour in the two genera, the following features distinguish them: lack of adhesive pseudopodia in the taxon described here, swimming behaviour, marginal flange to groove in organism described here, groove extending most of length of body in Carpediemonas, and acronematic posterior flagellum. When observed side by side, Carpediemonas has narrower flagella than Developayella, flagella of Developayella are less active, Developayella may use pseudopodia to ingest bacteria, and whereas the groove is well delineated in Carpediemonas, in Developayella it appears more like a simple flagellar pocket or depression. Jakoba libera also closely resembles this organism, but can be distinguished by orientation and adhesive nature of anterior flagellum (Patterson 1990) and its larger size. (ref. ID; 4872)