Meridion alansmithii

Brant 2003      Category: Araphid

Melosira varians


Meridion anceps

LM scalebar = 10 µm = 80 pixels.


Contributor: David R.L. Burge | Mark Edlund | Lynn Brant - June 2015
Length Range: 20-100 µm
Width Range: 3.5-5.5 µm
Striae in 10 µm: 14-20


Valves are narrow and linear-clavate, with an attenuated rostrate to subcapitate head pole. A single rimoportula is visible in LM. The rimoportula is positioned near the central sternum, near the widest part of the valve. The sternum is narrow and indistinct. Striae are continuous along the length of the valve. Costae are mostly primary, although secondary costae also are present. Costae number 4-6 in 10 µm and are often not visible near the foot pole.

Original Description

Author: Brant 2003
Length Range: 23-100 µm
Width Range: 3.5-5.5 µm
Striae in 10 µm: 15-20

Original Description

Frustules in girdle view wedge-shaped, attached valve face to valve face forming fan-shaped colonies. Valves heteropolar, hastate to clavate in valve view, length 23-100 µm width 3.5-5.5 µm. Valve tapering to subcapitate footpole with rounded to subcuneate headpole. On longer specimens margin between point of maximum width and apex of headpole somewhat concave. Position of maximum valve width about 1/4 the valve length from headpole. A narrow sternum runs the length of the valve. Transversely oriented rimoportula prominent, located on either side of sternum, usually from 1/5 to 1/3 the valve length from headpole. From 2 to 8 costae lie between head pole and rimoportula. Costae extend across part or entire width of valve, becoming much less prominent or absent near footpole, density 3-5 in 10 µm. Pore field present on foot pole, extending onto mantle. Numerous spines along valve face/mantle junction in some specimens. Striae uniseriate, extending onto mantle, density 15-20 in 10 µm.

Original Images

Cite This Page:
Burge, D., Edlund, M., and Brant, L. (2015). Meridion alansmithii. In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Meridion alansmithii

Contributor: David R.L. Burge | Mark Edlund | Lynn Brant

Reviewer: Sarah Spaulding


Brant, L.A. (2003). A new species of Meridion (Bacillariophyceae) from western North Carolina. Southeastern Naturalist 2: 409–418.

Rhode, K.M, Pappas, J.L. and Stoermer, E.F. (2001). Quantitative analysis of shape variation in type and modern populations of Meridion Ag. Journal of Phycology 37: 175-183.

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

Meridion alansmithii CAS

North American Diatom Ecological Database (NADED)

NADED ID: 1100

Autecology Discussion

Meridion alansmithii was described from an acidic (4.8-6.4 pH), low conductivity (12-42 µS/cm), and low nutrient temperate mountain wetland in North Carolina (Brant 2003). Samples were collected from squeezes of plants and other algae. Meridion alansmithii has only been reported from wetlands of North Carolina.