Staurosirella rhomboides

(Grunow) E.Morales and Manoylov 2010      Category: Araphid
BASIONYM: Fragilaria harrisonii var. rhomboides Grunow 1862
SYNONYM(S): Fragilaria leptostauron var. rhomboides (Grunow) Hust. 1931  | Staurosirella leptostauron var. rhomboides (Grunow) Andresen, Stoermer and Kreis 2000 

Staurosirella pinnata


Stephanodiscus alpinus

LM scalebar = 10 µm = 80 pixels.


Contributor: Eduardo A. Morales - October 2011
Length Range: 13-55 µm
Width Range: 5-9 µm
Striae in 10 µm: 6-9


Valves are rhomboid and slightly heteropolar. Valves with rounded ends. The central area is broad. The valve face is slightly to clearly undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular. Cells form short ribbon-like colonies, joined by linking spines. The axial area is lanceolate. Striae are distinct, composed of lineolae. Lineolae are greatest in length midway between the sternum and valve mantle, 6-9 in 10 µm. Lineolae bear finely branched volae. Striae are radiate and extend continuously onto the valve mantle. Costae are as broad as the striae. Spines are flat, spatulate bearing short ligulae on the side. Spines are present along the valve face edge, except at the apices, and are located on the costae between striae. Well-developed, ocellulimbus type, apical pore fields with round poroids are present. Apical pore field at headpole less developed than that of footpole. Pore fields are located at the junction between the valve face/mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and do not bear perforations. Valvocopulae are wider than other girdle elements. Cells form colonies attached to the substratum by a mucilage pad.

Original Description

Basionym: Fragilaria harrisonii var. rhomboides
Author: Grunow 1862
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Morales, E. (2011). Staurosirella rhomboides. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Staurosirella rhomboides

Contributor: Eduardo A. Morales

Reviewer: Sarah Spaulding


Grunow, A. (1862). Die österreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitäten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Meridioneae, Diatomeae, Entopyleae, Surirelleae, Amphipleureae. Zweite Folge. Familie Nitzschieae. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 12: 368, Pl. 7, fig. 8.

Morales, E.A., Manyolov, K.M. and Bahls, L.L. (2010). Three new araphid diatoms (Bacillariophyta) from rivers in North America. Proceedings of the Academy of Natural Sciences of Philadelphia 160(1): 29-46. 10.1635/053.160.0105

Smith, W. (1856). Synopsis of British Diatomaceae. John Van Voorst, London 1856. 2: 107pp., pls. 32-60, 61-62, A-E.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Staurosirella rhomboides CAS

North American Diatom Ecological Database (NADED)

NADED ID: 175017

Autecology Discussion

Cells form ribbon-like colonies with linking spines, attached by mucilage pads to the substrate.