Haslea amicorum, 2015

Sterrenburg, Frithjof A. S., Tiffany, Mary Ann, Hinz, Friedel, Herwig, Wulf E. & Hargraves, Paul E., 2015, Seven new species expand the morphological spectrum of Haslea. A comparison with Gyrosigma and Pleurosigma (Bacillariophyta), Phytotaxa 207 (2), pp. 143-162 : 155-158

H. amicorum Herwig, Tiffany, Hargraves & Sterrenburg , sp. nov. ( Fig. 65 LM, Figs 66–68 SEM)

Type:— " Birdrock, La Jolla, California, USA, January, 17, 2003, from Codium", geographic coordinates 32°48’N, 117°16’ W. Holotype BRM ZU9 /90, slide coordinates holotype: 4,3 E ; 14,5S. Isotypes in collection Sterrenburg # 728.

Valve rather broadly lanceolate, 32−39 μm long, 7.5–8.5 μm wide. Striae transverse radiate, circa 11 in 10 μm, longitudinal strongly curved, circa 22 in 10 μm. Axial and central areas inconspicuous in LM ( Fig. 65 ). In SEM, the tegumental layer shows continuous longitudinal fissures in the more peripheral portions of the valve, interrupted fissures in the more median portion ( Fig. 66, 67 ). At centre, there is an elliptical field not perforated by external areolar fissures ( Fig. 67 ). Central external raphe fissure elongated droplet-shaped, not deflected ( Fig. 67 ). Apical raphe fissures with V-shaped deflection, ending in depressions ( Fig. 68 ), apical pore present ( Fig. 68 , arrow). Basal layer with longitudinally elongated oblong foramina ( Fig. 65 ). Saepes not observed, no fragmented valves found.

Etymology:— The specific epithet refers to the spirit of this investigation.

Habitat:— Littoral marine, epiphytic and in plankton.

Distribution:— Known from the type locality (rare) and also observed (rare) in a plankton sample from the Mosquito Lagoon, a tributary of the Indian River Lagoon, Florida, USA.

Observations:— This species is rare in the materials collected and no valves presenting an internal view have been seen. From the LM image, the structure of the basal layer can be derived, however, with foramina that are about twice as long as they are wide. The strongly curved longitudinal striae are a particular feature of this species, which also has a special position in the genus Haslea because the more median longitudinal fissures, unlike the more peripheral, are not continuous throughout. Nevertheless, the continuous peripheral fissures and the presence of two separate layers in the valve, as evident from the LM image, warrant assignment to Haslea .

In H. amicorum the longitudinal striae are much finer than the transverse, which excludes a match with H. britannica , H. howeana or H. nautica .

A review of the literature yielded a species described as a Navicula but with the features of Haslea . It is here transferred:

Figures

FIGURES 65−68. H. amicorum sp. nov. Fig. 65. Holotype, LM. Bar = 10 μm. Fig. 66. Isotype, SEM, general view. Bar = 5 μm. Fig. 67. Isotype, SEM, exterior view, centre. Note interrupted longitudinal fissures in median portion of valve, continuous fissures towards margin. Bar = 1 μm. Fig. 68. Isotype, exterior view, apex.Arrow marks apical pore. Bar = 1 μm.