• Category
  • Length Range
    18-21 µm
  • Width Range
    7.5-8.5 µm
  • Striae in 10 µm
    9-10
  • Synonyms
    Navicula pseudanglica (Lange-Bert.) in Krammer and Lange-Bert. 1985

Identification

Description

Valves are elliptical, with rostrate to subcapitate apices. Striae are punctate, slightly curved and radiate. Near the center valve, 1-2 striae may be shorter in length than the remaining striae. The axial area is narrow. The central area is small and nearly round. The proximal raphe ends are straight and slightly expanded.

Navicula anglophila is similar to Placoneis elginensis, but P. elginensis has linear valve margins according to the original description of Pinnularia elginensis (Gregory 1856). Re-examination of the lectotype specimen of Placoneis elginensis by Cox (2003) also found P. elginensis valves are linear with a transverse central area.

The species illustrated on this taxon page was first proposed as Navicula pseudanglica Lange-Bertalot in Krammer and Lange-Bertalot (1985). In 1987, Lange-Bertalot recognized that his N. pseudanglica was a later illegitimate homonym of Navicula pseudanglica Cleve-Euler (1948). To correct the nomenclatural issue, Lange-Bertalot proposed the nom. nov., Navicula anglophila Lange-Bertalot in Lange-Bertalot and Krammer (1987) for his Navicula pseudanglica Lange-Bertalot (1985). However, Cox (Diatom Research issue is dated Dec 1987, but INA lists the date as 1988) transferred the taxon to Placoneis as Placoneis pseudanglica (Lange-Bertalot) Cox 1988. Subsequent workers have treated that name as either a valid transfer P. pseudanglica (Lange-Bertalot) Cox (see Cox 2003, Hofmann et al. 2013) or as a nom. nov. for N. pseudanglica as P. pseudanglica Cox (see CAS, Algaebase).

In 2005, Lange-Bertalot recognized that his taxon belonged in the genus Placoneis and proposed its transfer as P. anglophila (Lange-Bertalot) Lange-Bertalot in Metzeltin et al. (2005), based on his recognition of N. anglophila Lange-Bertalot in Lange-Bertalot and Krammer (1987) as the legitimate nom. nov. Lange-Bertalot (2005) recognized Cox's Placoneis pseudanglica (Lange-Bertalot) Cox as invalid, which it is not, rather he should have referred to P. pseudanglica (Lange-Bertalot) Cox as illegitimate. It seems that the jury has fallen on the side of recognizing this taxon as P. pseudanglica Cox 1987/1988? as the proper name, but because Cox's transfer was actually dated 1988 (as noted by CAS and INA), there was a legitimate and validly published available name in place for this taxon, i.e. Navicula anglophila Lange-Bertalot in Lange-Bertalot and Krammer (1987), for which Cox should have based her transfer. Because Lange-Bertalot published his nom. nov. (Navicula anglophila Lange-Bertalot) before Cox's 1987/1988? transfer to Placoneis (essentially superfluous nom. nov), we have to accept the Lange-Bertalot’s (2005) transfer to Placoneis as the correct name for this taxon, i.e. Placoneis anglophila (Lange-Bertalot) Lange-Bertalot in Metzeltin et al. (2005).

Had Cox published her combination Placoneis pseudanglica Cox before Lange-Bertalot published his new name (Navicula anglophila Lange-Bertalot), her name Placoneis pseudanglica Cox would have priority as a nom. nov. based on ICN Art 41.8 (see example 21(c)).

Autecology

Placoneis anglophila was found in epipelon in Beck’s Canal and in epipsammic samples from Silver Lake, both in Dickinson Co., Iowa. According to Cox (2003) it is found in slightly eutrophic to eutrophic freshwater.

Placoneis Pseudanglia1
Credit: USGS BioData
Distribution of Placoneis pseudanglica in rivers of the continental U.S. based on the National Water Quality Assessment program. Retrieved 03 June 2015.

Original Description

  • Basionym
    Navicula anglophila
  • Author
    Lange-Bert. 1987
  • Length Range
    26-40 µm
  • Width
    10.5-15 µm
  • Striae in 10µm
    9-10 in the center valve, up to 14 at the ends

Original Images

N Pseudanglica Orig Desc 1985
N Pseudanglica Orig Image 1985
N Anglophila Orig Desc 1987

EMAP Assessment

EMAP Distribution

Placoneis Pseudanglica   Lange  Bertalot   Cox 10
Map 10

Response Plots

Planothidium Apiculatum   Patrick   Lange  Bertalot

Cite This Page

Salas, E, and Bishop, I, and Burge, D, and Edlund, M. (2015). Placoneis anglophila. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/placoneis_anglophila

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Placoneis anglophila 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.