Seven new species expand the morphological spectrum of Haslea. A comparison with Gyrosigma and Pleurosigma (Bacillariophyta)
Author
Sterrenburg, Frithjof A. S.
Author
Tiffany, Mary Ann
Author
Hinz, Friedel
Author
Herwig, Wulf E.
Author
Hargraves, Paul E.
text
Phytotaxa
2015
2015-05-08
207
2
143
162
http://dx.doi.org/10.11646/phytotaxa.207.2.1
journal article
10.11646/phytotaxa.207.2.1
1179-3163
13637746
H. avium
Tiffany, Herwig & Sterrenburg
,
sp. nov.
(
Figs 19, 20
: LM. 58–64: 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
:
4,4 E
;
3,4 S
,
isotype
:
4,8 E
; 5,3.
Isotypes
also in collection
Sterrenburg
# 728.
Valve (
Figs 19, 20
) robust, lanceolate, 38–45 μm long, 6–9 μm wide, with acute apices. Striae transverse slightly radiate, circa 13–15, longitudinal much finer, circa
30 in
10 μm. A few central transverse striae somewhat more radiate and slightly shortened, leaving a tiny more or less oval central area, but this is variable (
Figs 19
,
59, 64
). Axial area extremely narrow, inconspicuous in LM. In
SEM
, the tegumental layer, with longitudinal fissures that are continuous over most of the valve but sometimes interrupted near the central area, may show marked surface relief (
Figs 60, 62
, but not in
Fig. 63
). External raphe fissures often undulating in the middle (
Fig. 62
, less so in
Fig. 63
), central endings tightly curving hooks that
form depressed
pits with tooth-like projections (
Figs 62, 63
), external terminal endings deeply depressed and retrograde (
Fig. 60
). Internally, no central bars apparent, one side of the raphe ridge thickened but no pronounced accessory silica ridge paralleling the raphe ridge present (
Figs 59, 64
). The entire internal raphe ridge, including the central raphe node, tilted sideways (
Fig. 64
). Basal layer: foramina longitudinally elongated oblong, transverse bars of the grate considerably broader than the longitudinal (
Fig. 64
).
Etymology:—
The specific epithet (genitive, plural of Latin “avis” = bird) refers to the birds of the
type
locality.
Habitat:—
Littoral marine, epiphytic and in sediment.
Distribution:—
Known from the
type
locality only, not rare, also in several other samples from the Birdrock locality in collections
Tiffany
and
Sterrenburg
.
Observations:—
This species somewhat resembles
H. tsukamotoi
and
H. meteorou
with regard to the marked surface relief of the robust valve, the hook-shaped external central raphe endings with tooth-like projections and the sideways tilted internal central raphe node, but the external central raphe endings and tooth-like projections are very different in shape. Also, the basal layer and striation are clearly different. Saepes not satisfactorily visualized, no fragmented valves found.
In LM, this species may be readily mistaken for one of the
Naviculae sensu stricto
(the “
Lineolatae”
) but the SEM images are decisive. In
Fig. 63
the coarse transverse bars of the basal layer grate “shine through” the tegumental layer as ghost images, permitting a transverse stria count in the SEM material. Without this, it would not have been possible to verify that the exterior views of
Figs 58, 60 and 62
and the interior views of
Figs 59, 61 and 64
are indeed of the same species.
In
H. avium
the longitudinal striae are much finer than the transverse, which excludes a match with
H. britannica
,
H. howeana
or
H. nautica
.