Identification

Description

Valves are slightly dorsiventral and nearly lanceolate. The ends are subrostrate and slightly deflected toward the ventral side. The dorsal margin is broadly rounded and the ventral margin is convex. The raphe is lateral becoming reverse-lateral near the proximal ends. The proximal raphe ends are slightly expanded and deflect dorsally. The distal raphe ends are strongly deflected ventrally and extend to the valve margin. The axial area is narrow and parallel. Central area is small, and slightly or moderately rounded on the dorsal side. Striae radiate throughout appearing parallel at the center. Areolae are not distinguishable under LM. This species is small and lightly silicified.

Note that several nearly lanceolate species are placed in either Encyonema or Encyonopsis. The generic circumscriptions are currently not clear and need to be revised.

Autecology

Encyonema evergladianum was originally described by Krammer from samples collected in the Florida Everglades, USA. The specimens used for the current species treatment are also from the Florida Everglades where they were collected from periphyton mats, a characteristic feature of this landscape. The periphyton mats are composed of benthic algae, bacteria, fungi, and detritus and, in the karstic, freshwater wetlands of the interior Everglades, have a calcium carbonate top layer precipitated by cyanobacteria growing in mats (Gaiser et al. 2011, Hagerthey et al. 2011). The samples used for this description were collected along a transect spanning karstic, freshwater wetlands up to the interior edge of the fringing, coastal mangroves within Everglades National Park (see below). The Florida Coastal Everglades Long Term Ecological Research Program reports the presence of E. evergladianum at several other locations throughout South Florida.

The USGS BioData program reports E. evergladianum in rivers and in Central Texas, but these records have not been confirmed.

Dscf2902
Credit: Nick Shulte
Calcareous periphyton mat from the Florida Everglades, USA

Original Description

Merkmale Quant: Lange 13-28 µm, Breite 3.7-5 µm, maximaler Lange/Breite-Quotient 5.6, 21-23 Transapikalstreifen/10 µm, 37-42 Punkte/10 µm Umriß: Wenig dorsiventral, lanzettlich, Dorsal- und Ventralseite maßig konvex Enden: Schwach rostrat abgesetzt, schmal gerundet, Schultern nur auf der Ventralseite wenig angedeutet Areae: Axialarea eng, linear; Zentralarea fehlt. Raphe: Filiform, proximal nach dorsal abgebogen, Raphenaste ventral gekurvt, Endspalten nahe dem Schalenrand ventralwarts laufend. Streifen: Dorsal (r) / (r), ventral (r / (r) Punkte: Im LM nur bei extrem shragem Licht erkennbar Diagnose: Merkmalskombination: Umriß; morphometrische Daten. Ahnliche Arten: E. rifelanum (grober gestreift); E. truncatum (grober gestreift); E. guatemalum (,,Kleinform" von E. evergladianum)

Okologie Verbreitung: Typenhabitat. Haufigkeit: Im Typenmaterial haufig

Bemerkungen Fig. 142: 8 aus den kolumbianischen Anden konnte eine kleine Form von E. evergladianum sein. Da es sich aber um ein Einzelexemplar handelt, ist eine sichere Zuordnung nicht moglich. Sehr ahnlich ist auch das Einzelexemplar aus einem Fischteich im Schwalmtal bei Bruggen (Fig. 142: 12), das mit 22-24 Transapikalstreifen/10 ebenfalls sehr fein gestreift ist. Eine kleine, wahrscheinlich auf einer Schale beruhende Encyonema mit lanzettlichem Umriß hat CHOLNOKY (1956) als Cymbella psammophila beschrieben (Fig. 141, 28). Dieses Taxon hat eine große, rhombischrundliche Area, wie wir sie sonst bei keiner anderen Encyonema finden.

  • Author
    Krammer 1997
  • Length Range
    13-28 µm
  • Width
    3.7-5 µm
  • Striae in 10µm
    21-23

Original Images

Krammer Original

Cite This Page

Mazzei, V. (2014). Encyonema evergladianum. In Diatoms of North America. Retrieved August 19, 2018, from https://diatoms.org/species/encyonema_evergladianum

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Encyonema evergladianum from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.