Chamaepinnularia thermophila (Bacillariophyceae): synonymy with Navicula tongatensis Hustedt and update of its geographic distribution and ecology

Figure 1

Figure 2(a–v)

Figure 3(a–u)

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Figure 5

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Physical and chemical variables of the sites with Chamaepinnularia thermophila (including the new site of the San Giovanni Su Anzu spring in Sardinia, Italy), relative abundance of the species and occurrence on different substrates

Variables	Units	Country
		Guadalupe		Martinique	Sardinia
		Spring sites
		Chute du Carbet	La Lise	Sucrerie	San Giovanni Su Anzu
Temperature	°C	44.9	44.9	26.4	29.3–30
Discharge	Is- 1				0.489–0.651
Mean water depth	cm				6–7.3
pH		6.51	7.33	7.92	7.26–7.30
Alkalinity	meq l-1				3.8–4.7
Conductivity	μS cm-1			1558	570–590
Dissolved Oxygen				7.07	7.2–8.7
Oxygen saturation	% saturation			89.2	95–114
BOD5	mg O2 l-1				1.0–3.3
Cl		368	27.5		42.5–46.1
Total hardness	mg CaCO3 l-1				235–235
Reactive phosphorus					16–24
Total phosphorus	μg P l-1				37–78
N-NO2-	μg N l–1				4–6
N-NO3		200	1140		2448–2932
N-NH4					3–8
Total nitrogen					3743–6244
Reactive silica	mg Si l–1	110	72		7.53–8.65
Suspended solids	mg l–1				0–1.8
Br-					< D.L.0.4
Ca2+		188	13.4		44–44
F					<D.L.–0.1
Fe2+					0.04–0.04
HCO3-		125	132		254.4–274.5
K+		24	3.89		1.7–2.2
Mg2 +		64.9	4.84		30.4–30.9
Mn2 +		n.d.	0.011		0.04–0.05
Na+		116.2	41.9		26–27.3
SO42 -		303	5.69		8.0–9.8
% C. thermophila		10–50%	< 10%	55	0.9–10.8
Substrate				cob	cob/mac/sed

Main characteristics and the type locality of Navicula thermophila and Navicula tongatensis reported in the original descriptions of the species

	Navicula thermophila Manguin in Bourrelly & Manguin 1952	Navicula tongatensis Hustedt 1962
Valve outline	elliptic	linear-elliptic
Ends	capitate	sub-capitate
Raphe		straight, filiform
Striae	radiate, more spaced in the middle	slightly radiate, more spaced in the middle
Central area	sub-quadratic
Length (μm)	7.2–8.0	6.0–8.0
Width (μm)	2.5–3.0	2.5
Striae/10 μm	29–30	26–28
Type locality	hot-salt spring	thermal well