Gomphonema californicum

Stancheva and Kociolek 2016      Category: Asymmetrical biraphid

Gomphonema brebissonii

 

Gomphonema caperatum

LM scalebar = 10 µm = 80 pixels.



Observations

Contributor: Rosalina Stancheva - December 2016
Length Range: 22-69 µm
Width Range: 5.6-8.3 µm
Striae in 10 µm: 10-15

Description

Valves are lanceolate-clavate with a rounded headpole and narrower footpole. Striae are slightly radiate at the center of the valve (10-13 in 10 µm) and up to 15 in 10 µm near the apices. Striae are strongly radiate toward the footpole. Striae are composed of areolae (28-32 in 10 µm) clearly distinguishable near the center and headpole. The axial area is narrow and lanceolate. One, occasionally two, median striae on both sides of the central area are shorter than the others. The central area is rectangular and transversely extended, or rarely elliptic, delimited by two or three curved striae. One isolated stigma is positioned close to the proximal raphe ends. The raphe is lateral and slightly undulate. Frustules are slightly cuneate in girdle view. Striae extend onto the mantle where pores form an irregular single row, becoming double near the head pole, interrupted or continuous near the middle. A small single apical spine is present at the head pole, which is better observed in girdle view. In some specimens, the spine may be very small or missing, but in other specimens is pronounced and clearly visible with LM.

Under SEM, striae are uniseriate and composed of slit-like (lineola-like) areolae, which extend onto the mantle. Areolae near the headpole are coarser and longer than the areolae near the footpole. Areolae adjacent to the axial area are shorter and slightly undulate or c-shaped. Small areolae with circular external openings form: 1) the tips of the median short striae and the adjacent two or three striae, and 2) the entire basal stria at the foot pole. Distal raphe ends are deflected before the apices and extend into the mantle. In the central area, one isolated stigma with a circular opening is positioned close to the dilated and drop-shaped proximal raphe ends. Apical pore field with porelli, separated from striae by a hyaline area is present at the footpole. The porelli are either regularly ordered within the apical pore fields or split by a narrow, unornamented area.



Original Description

Basionym:
Author: Stancheva and Kociolek 2016
Length Range: 22-67 µm
Width Range: 5.6-8.3 µm
Striae in 10 µm: 10-15

Original Description

Gomphonema californicum Stancheva & Kociolek, sp. nov. (Figs 1–27)

LM observations

Valves are lanceolate-clavate with rounded head pole and narrower foot pole. Cells are 5.6–8.3 μm wide, 22–67 μm long (Figs 1–13); initial cell 10 μm wide, 71 μm long (Fig. 14). Striae are slightly radiate at the center of the valve 10–13 in 10 μm, becoming denser up to 15 in 10 μm near both apices and strongly radiate toward the foot pole. Striae composed of areolae, which are coarser and distinguishable near the head pole, 28–32 in 10 μm. Striae sometimes are interrupted, particularly around the central area (Figs 2 and 3). Axial area narrow, lanceolate. One, occasionally two median striae on both sides of the central area are shorter than the others (Figs 4–6). Central area is rectangular transversely extended, delimited by two or three curved striae (Figs 2, 6, 8, 10), rarely elliptical (Fig. 4). One isolated stigma is positioned close to the proximal raphe ends. Sometimes one or a few small indistinct depressions are present in the central area, not easily resolvable with LM (Fig. 2). The raphe is lateral, slightly undulate. Frustules are slightly cuneate in girdle view with single or double irregular rows of puncta on each mantle, in some specimens interrupted near the middle (Figs 12 and 13).

SEM observations Externally, striae are uniseriate, composed of slit-like (lineola-like) areolae, which extend onto the mantle (Fig. 15–18). Areolae near the head pole (Fig. 19) are coarser and longer than the areolae close to the foot pole (Fig. 20). Areolae adjacent to the axial area are shorter and slightly undulate or c-shaped (Figs 15, 16, 19). Small areolae with circular external openings form: (1) the tips of the median short striae and the adjacent two or three striae (Figs 22, 23), and (2) the entire basal stria at the foot pole (Figs. 17, 18, 20). Apical pore field with porelli, separated from striae by a hyaline area is present at the foot pole (Figs 15–18, 20). The porelli are either regularly ordered within the apical pore fields (Fig. 15) or split by a narrow, unornamented area (Fig. 20). Distal raphe ends are deflected before the apices and extend into the mantle (Figs 19, 20). A small single apical spine is present at the head pole (Fig. 19), better observed in girdle view (Figs 17, 18, 21). In some specimens the spine may be very small or missing (Fig. 16), but in other specimens is pronounced and visible with LM (Fig. 13) In the central area, one isolated stigma with a circular opening is positioned close to the dilated and drop-shaped proximal raphe ends (Figs 22, 23). Sometimes, one or two small indistinct depressions are visible near the stigma in the central area (Fig. 23). These do not extend through the valve and are not visible on the internal side of the valve. Each mantle with pores in an irregular single row, becoming double near the head pole, and more widely spaced near the middle (Figs 17, 18). Internally, the helictoglossa and pseudosepta are visible at both poles (Figs 24, 27). The central nodule is slightly raised, bearing a slit-like stigma opening and dilated and recurved proximal raphe ends (Figs 25, 26).

Type:—USA. California: Digger Creek, Sierra Nevada Mts, 40.44284º N, 121.72501º W, Nathan Mack, August 31, 2015 (holotype UC2050494 circled specimen on slide; isotype RS! 007, circled specimen on slide and material, CSUSM, USA).

Etymology:—The epithet refers to the USA state of California, where the species was first observed.

Distribution and ecological notes:—Found in four sites in the Sierra Nevada Mts, CA (elevation 1133 to 1902 m a.s.l.). Habitats are generally characterized by low nutrients (total nitrogen (TN) <0.1 mg L-1, total phosphorus (TP) <0.05 mg L-1), low conductivity (<107.6 μS cm-1), slightly alkaline (35–76 mg L-1 CaCO3), and pH 8.1–8.5 (see Table 1).

Comments: —In terms of outline, and overall dimensions, this species resembles G. dichotomum Kützing (1833: 569) as illustrated by Reichardt & Lange-Bertalot (1991) and G. grasmueckii Lange-Bertalot & Reichardt (Lange- Bertalot 1993). Striae densities of both diatoms, however, are lower compare to the California specimens having striae that are 10–13 in 10 μm, and rarely up to 15 in10 μm (Table 2). Furthermore, the shape of central area differs among three species, being significantly smaller in G. grasmueckii. Perhaps more importantly, ultrastructurally the three species are quite different. Reichardt & Lange-Bertalot (1991) show G. dichotomum to have large c-shaped areolae uniform throughout the entire valve , while in G. californicum the areolae are variable in shape. In G. grasmueckii areaolae are lineola-lake and circular, but the stiae are only partially uniseriate, becoming biseriate toward the mantle (Lange-Bertalot 1993). The presence of an apical spine at the head pole is an unique feature of G. californicum.

Original Images


Cite This Page:
Stancheva, R. (2016). Gomphonema californicum. In Diatoms of the United States. Retrieved June 25, 2017, from http://westerndiatoms.colorado.edu/taxa/species/gomphonema_californicum

Species: Gomphonema californicum

Contributor: Rosalina Stancheva

Reviewer: Sarah Spaulding

Citations

Lange-Bertalot, H. (1993). 85 Neue taxa und uber 100 weitere neu definierte Taxa erganzend zur Subwasserflora von Mittleuropa. Bibliotheca Diatomologica 27, 454 p. Cramer, Berlin, Stuttgart.

Reichardt, E. and Lange-Bertalot, H. (1991). Taxonomische Revision des Artencomplexes um Gomphonema angustum—G. dichotomum—G. intricatum—G. vibrio und ahnliche Taxa (Bacillariophyceae). Nova Hedwigia 53(3-4): 519-544.

Stancheva, R., Sheath, R.G. and Kociolek, J.P. (2016). New freshwater gomphonemoid diatoms from streams in the Sierra Nevada mountains, California, USA. Phytotaxa 289 (2): 118-134.

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)

NADED ID:

Autecology Discussion

Gomphonema californicum was described from California, where it is found in remote oligotrophic streams (Digger Creek, Rice Creek, Bailey Creek and Butte Creek) in the Sierra Nevada mountain range (Stancheva et al. 2016). The sites ranged in specific conductance (26 - 108 µS/cm), pH (8.1-8.5), orthophosphate as P (0.04-0.07 mg/L) and nitrate plus nitrite as N (0.008-0.023 mg/L).