• Category
  • Length Range
    32.8-57.4 µm
  • Width Range
    6.1-7.8 µm
  • Striae in 10 µm
    13-16
  • Reported As
    Gomphonema appalachianum (Thomas et. al 2009, pg. 227, Pl. 11, Fig 112-115)

Identification

Description

Valves are lanceolate-clavate with a rounded headpole and footpole. The axial area is broadly lanceolate and expanded at center valve. Raphe is lateral, with proximal raphe ends narrowly separated.The central area lacks a stigmoid. Striae are parallel to nearly parallel at center valve, becoming barely radiate at the apices.

The species G. appalachianum, also described from the southeast (Thomas et al. 2009), appears to be a later heterotypic synonym of G. christenseni. Here, the type images of G. christenseni are presented. Our observations of the G. christenseni specimens on the holotype slide is consistent with the original description (below). Note that in Thomas et al. (2009), images portraying G. christenseni appear to be an undescribed taxon. The specimens portrayed as "G. christenseni by Thomas et al. are considerably broader than the original description, and range in breadth from 8.4-11.2 µm (Pl. 11, Figs 109-11).

Autecology

This taxon was originally described from the Great Smoky Mountains, where it was found in many streams in lower elevations, in low abundance. More recently, it has been found in low numbers in other rivers of the southeast (US Geological Survey regional survey of 2014).

The species has also been reported from the Kumano River, from Kirishima Heights, and from Lake Biwa, Japan (Tuji 2003).

Original Description

Valvae lineari-clavate, 32-62 X 6-8 μm, parviores rotundatae et subapiculatae. Area axialis extremis distalibus parva, ad centrum proper strias incompletas expansa. Area centralis ut videtur silliceor quam pars major valvae. Raphe filiformis. Striae 12-13 per 10 μm, versus medium valvae parallelae, extremibus plus minus radiatae.

Holotypus: A.N.S.P. - G.C. #53920, in collectione diatomarum Academiae Scientarum Naturalium Philadelphiae.

Valves linear-clavate, becoming rounded and almost apiculate in smaller specimens. Valve length 32-62 μm, breadth 6-8 μm. Axial area small at the distal ends, becoming expanded due to a shortening of the striae towards the central area. Central area appears more heavily silicified than the rest of the valve and lacks an isolated punctum or stigma. Striae parallel at mid-valve, becoming slightly radiate at the ends. Striae 12-13 in 10 μm. Raphe filiform.

Holotype: A.N.S.P. -G.C. #53920. In general diatom collection, Academy of Natural Sciences of Philadelphia.

Type locality: Great Smoky Mountains. National Park, Big Creek 100 m downstream from foot bridge, Big Creek Watershed, epiphytic on submerged Fontinalis. Collected by R. Lowe, 9-15-77 #5-3.

GSMNP Distribution: Observed at lower elevations in many streams, however, never in large numbers.

  • Author
    R.L.Lowe and Kociolek 1984
  • Length Range
    32-62 µm
  • Width
    6-8 µm
  • Striae in 10µm
    12-13

Original Images

Gomphonema christenseni orig illus
G Christenseni Origdes

Cite This Page

Vaccarino, M, and Tyree, M. (2016). Gomphonema christenseni. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/gomphonema_christenseni

Responses

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