Craticula sardiniana Bahls, 2013

Bahls, Loren, 2013, New diatoms (Bacillariophyta) from western North America, Phytotaxa 82 (1), pp. 7-28 : 23-25

Craticula sardiniana Bahls , sp. nov. ( Figs 96–101 )

Synonym: —“ Craticula silviae ” nov. spec. prov. Lange-Bertalot (2001: 412)

Reported as: —(?) Craticula acidoclinata Lange-Bertalot et al. (2003: 176) .

Valves lanceolate with broadly rounded, unprotracted apices. Valve length 68–113 µm; valve width 15.6–19.5 µm. Axial area linear and narrow. Central area elliptic with convex sides, about two times wider than axial area. Raphe weakly lateral with straight and slightly inflated proximal ends. Striae parallel in the middle, becoming weakly radiate, then convergent near the apices, 14 in 10 µm at the valve center to 18 in 10 µm near the apices. Areolae 26 in 10 µm. Craticula valves observed; “Heribaudii” valves not observed.

Holotype:— CANADA, Alberta: Waterton Lakes National Park, Indian Springs Pond , 49.1297 o N, 113.8731 o W, elev. 1372 m, coll. B. Johnston, 5 June 2009. MDC sample 454301; holotype slide MDC 124-1 ( Figs 96, 98 ) (circled holotype specimen in Fig. 96 ). MONTU!

Isotypes: —MDC slide 40-26 (MONTU!); ANSP GC 65100.

Paratypes: — USA, Montana: Beaverhead County, Skinner Pond No. 1, 45.1728 o N, 113.5136 o W, elev. 2252 m, coll. L. Bahls, 11 July 2010. MDC sample 460301; MDC slides 37-22, 124-54 ( Figs 97, 99–101 ). MONTU !

Etymology:—This taxon is named after the island of Sardinia, where it was first reported.

Observations:— Craticula acidoclinata ( Lange-Bertalot & Metzeltin 1996: 41) has wider valves (16–24 µm) with narrower, weakly protracted apices. Craticula cuspidata has rhombic-lanceolate valves, much narrower apices, and a central area with concave sides. Craticula johnstoniae sp. nov. ( Figs 90–95 ) has rostrate to subcapitate apices.

Distribution and Ecology: — Craticula sardiniana has been collected from two ponds in the northern Rocky Mountains where pH ranges from 7.8 to 8.1 and specific conductance from 302 to 313 µS/cm. Its preference for alkaline waters with higher electrolyte content sets this taxon apart from Craticula acidoclinata , which prefers acidic or circumneutral waters with very low concentrations of dissolved solids. In Sardinia, C. sardiniana was collected from rock pools rich in electrolytes ( Lange-Bertalot et al. 2003).

Order Surirellales D.G. Mann in Round et al. 1990: 656

Family Surirellaceae Kützing 1844: 58

Genus Cymatopleura W. Smith 1851: 12

Figures

FIGURES 90–101: Craticula johnstoniae, Craticula sardiniana. Figs 90–95: Craticula johnstoniae. Figs 90–93: Akamina Pools, Waterton Lakes National Park, Alberta (type locality). Fig. 90: Holotype specimen. Fig. 91: “Heribaudii“ valve. Fig. 94: Pond near Park Lake, Jefferson County, Montana. Fig. 95: Indian Springs Pond, Waterton Lakes National Park, Alberta. Figs 96–101: Craticula sardiniana. Figs 96, 98: Indian Springs Pond, Waterton Lakes National Park, Alberta (type locality). Fig. 96: Holotype specimen. Figs 97, 99–101: Skinner Pond No. 1, Beaverhead County, Montana. Scale bars: 10 µm.