• Category
  • Length Range
    23.9-48.9 µm
  • Width Range
    9.1-13.2 µm
  • Striae in 10 µm



Valves are linear-lanceolate, becoming slightly triundulate in larger specimens. Apices are cuneate. Striae are radiate, becoming more dense near the apices. The central area is transversely oriented, incomplete, asymmetric, and characterized by a distinct stigma. Few to many puncta are erratically scattered near the central area margin. The axial area is moderately narrow and lanceolate. Longitudinal lines are visible along the valve margin. The raphe is narrowly lateral, with hooked distal ends and proximal ends deflected to the opposite side. Areolae are coarse and easily visible in LM, measuring 18-20 in 10 µm.


Patrick (1959) described this taxon from Pennsylvania. Although species in the genus Luticola are often found in soils and aerophilic habitats, we verified records in samples from rivers of Georgia and South Carolina. Along with Sellaphora japonica, L. minor is found both in rivers of the southeastern U.S. and in Japan - a curious disjunct distribution. L. minor has been reported from Japanese springs and rivers (Mayama and Kawashima, 1998).

Luticola minor is similar in shape to L. submobiliensis, but the valve length to width ratios of each taxon are distinct (below).

Minor Submobiliensis
Credit: Meredith Tyree
Comparison of length and width measures of L. minor (red circles) and L. submobiliensis (blue triangles).

Original Description

Navicula mobiliensis var. minor var. nov.

Valva lineari ad linearem lanceolatam, apicub cuneatis. Area axiali distincta. Area centrali transversa. Stigma distincta in uno latere nodulis; compluribus punctis in altera latere areae centralis quae sunt separatae ab apicubus striarum. Striis radiatis per valvam. Longitudo, 34-43 μ (specimen typicum, 41 μ). Latitudo, 10-12 μ (specimen typicum, 11 μ). Striae, 16 in 10 μ in media valvae usque 24 in 10 μ apicibus valvae.

Valve linear to to linear-lanceolate, with wedge-shaped ends. Axial area distinct, central area transverse. On one side of the central nodule a distinct stigma; on the other side of the central area several puncta which are isolated from the ends of the striae. Striae radiate throughout the valve. Length, 34-43 μ (type, 41 μ). Breadth, 10-12 μ (type, 11 μ). Striae, 16 in 10 μ at center of valve to 24 in 10 μ at ends of valve.

The shape of the valve and the general characteristics of the axial and central areas are similar to that of the nominate variety. This variety differs in its smaller size, finer striae and the presence of several isolated puncta near the ends of the striae on the side of the central area opposite to the side bearing the stigma. Puncta usually 20-22 in 10 μ.

Specimen illustrated.--A-G.C. 44497 (holotype). Type locality.--Pennsylvania, Chester County, Ridley Creek near Garrett Mill Road, approximately one-fourth mile upstream from West Chester Pike, J. Wallace, November 1951. Distribution.--Only known from the type locality.

  • Basionym
    Navicula mobiliensis var. minor
  • Author
    R.M.Patrick 1959
  • Length Range
    34-43 µm
  • Width
    10-12 µm
  • Striae in 10µm

Original Images

L Minor Origfig
L Minor Origdesc

Cite This Page

Tyree, M, and Bishop, I. (2016). Luticola minor. In Diatoms of North America. Retrieved August 19, 2018, from https://diatoms.org/species/luticola_minor


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