Nova Hedwigia, Beiheft 141, 141–154 ArticleStuttgart, März 2012

© 2012 J. Cramer in Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany www.borntraeger-cramer.de 1438-9134/2012/0141-0141 $ 1.25

Fragilariforma horstii sp. nov. (Bacillariophyceae) a new araphid species from the northern United States of America

Eduardo A. Morales1, 2 *, Kalina M. Manoylov3 and Loren L. Bahls4

1 Herbario Criptogámico Universidad Católica Boliviana, Carrera de Ingeniería Ambiental, Casilla de Correos 5381, Cochabamba, Bolivia

2 Patrick Center for Environmental Research, The Academy of Natural Sciences of Philadelphia, PA 19103-1195, USA

3 Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, GA 31061, USA

4 Montana Diatom Collection, 1032 12th Avenue, Helena, Montana 59601, USA

* Corresponding author: edu.morales2006@gmail.com

With 21 fi gures and 2 tables

Abstract: A new taxon, namely Fragilariforma horstii E. Morales, Manoylov & Bahls, is described from rivers in the northern United States of America. Light (LM) and scanning electron microscopy (SEM) data reveal that the taxon has several features congruent with taxa currently placed in Fragilariforma D. M. Wil-liams & Round such as uniseriate striae recessed between thickened costae, simple round areolae, spines on the costae at the valve face/mantle junction, a portula along a stria, developed apical pore fi elds, and ligulate, open girdle bands. However, the taxon also exhibits unique features that justify its separation at the species level from any currently known taxon within Fragilariforma: 1) the spines are subtended by a siliceous ring having short extensions projecting onto the valve face, 2) there is a portula lacking a labi-ate internal structure, and 3) the girdle bands lack perforations. Among Fragilariforma spp. producing a cruciform shape, the new species is distinguished by the tapering and narrowly rounded apices and the much higher stria density. The new taxon is circumneutral to acidophilous and oligo- to mesotraphentic. A discussion is presented about the morphology and ecology of this taxon in the light of pertinent literature.

Key words: Fragilariforma horstii sp. nov., Bacillariophyceae, araphid diatoms, United States of America

Introduction

The genus Fragilariforma was established to include taxa related to Fragilaria virescens (Ralfs) D. M. Williams & Round (Williams & Round 1987, 1988). The species in the genus are com-monly reported from oligotrophic, dystrophic waters varying from slightly to strongly acidic (Renberg 1977, Charles 1986, Williams 1990, Kingston et al. 2001, Kilroy et al. 2003). The most

K-NOVA141.indb 141 25.01.2012 07:04:21

eschweizerbart_xxx

142 E. A. Morales et al.

salient characteristics highlighted in the genus protologue (Williams & Round 1987) are produc-tion of uniseriate striae composed mostly of round areolae bearing simple vela. These striae run from the narrow (barely visible and sometimes absent) central sternum onto the valve mantle. The spines are tubular and located at the junction of the valve face/valve mantle border. Apical pore fi elds are simple, as opposed to being of the ocellulimbus type, the distinguishing character-istic from Fragilaria Lyngb. (Williams 1996). These apical pore fi elds are more or less developed and are composed of round poroids. Girdle bands are open, ligulate, and bear a single row of round areolae. One rimoportula is located along a stria at one of the valve apices.

In recent years, the concept of the genus has been implicitly expanded by insertion of new taxa without rimoportula or having two rimoportulae, one at each valve apex (Williams 1990, Krammer & Lange-Bertalot 1991, Kilroy et al. 2003). In the case of Fragilariforma fl oridana (Hanna) D. M. Williams, there is absence of apical pore fi elds and of areolae on the valve mantle. The girdle bands in this taxon have been shown to bear scattered areolae on the pars interior and exterior a characteristic unique to this diatom (Williams 1990). More recently, Metzeltin & Lange-Bertalot (2007) found populations of F. fl oridana, F. spinulosa (Patrick) Metzeltin & Lange-Bert. and their newly described species F. hamiltonii Metzeltin & Lange-Bert. and F. wil-liamsii Metzeltin & Lange-Bert. having a clear hyaline area around the valve face edge. This is a region at the valve face margin with fi lled in striae, more noticeable and wider in representatives having a swollen central area (see for example fi gs 1 and 2 in their Plate 22, p. 311).

While some features of all known species have been clearly studied, such as presence and lo-cation of spines, more or less faint axial area, the uniseriate character of the striae and the general appearance of the areolae, other features merit further research. For example, the literature (i.e., compare fi gures and text in Kilroy et al. 2003 and Williams & Round 1987) is ambiguous about the tubular character of the spines, and the structure, absence or presence, number, location of the rimoportulae. As more detailed studies are produced further character variations might be reported.

In the present work we report a taxon, Fragilariforma horstii sp. nov., from streams in the northern United States that has strong affi nities with taxa currently placed in Fragilariforma, but that it presents three characters different from those of any species reported thus far, namely: 1) spines with a ring of silica with short extensions onto the valve face, 2) portula lacking a labiate internal structure, and 3) girdle bands without perforations. Additionally, the taxon has a cruci-form valve shape with tapering and narrowly rounded apices, as well as a very high density of striae. Both of the latter features readily distinguish the taxon from other Fragilariforma spp. producing a cruciform shape, e.g. Fragilariforma fl oridana, F. hamiltonii, F. lata (Cleve-Euler) D. M. Williams & Round, F. lata var. acuta Flower, F. spinulosa, F. stevensonii Metzeltin & Lange-Bert. and F. williamsii. A discussion of the morphology and ecology of this new taxon in the light of published literature is also presented herein.

Materials and methods

Samples used in this study are listed in Table 1. Montana periphyton and environmental samples were collected by the Montana Department of Environmental Quality (MDEQ) for various moni-toring and assessment projects. Collection and analysis methods followed MDEQ standard oper-ating procedures located at http://www.deq.state.mt.us/wqinfo/monitoring/SOP/sop.asp. These samples were preserved with Lugol′s (IKI) solution, digested with concentrated sulfuric acid and potassium dichromate, washed by decanting with distilled water, and air-dried aliquots mounted on glass slides using Naphrax. The microscope used for photography was a Leica DMLB2™ with Nomarski DIC. The camera used with this microscope is a Spot Insight QE Model No. 14.0 monochrome digital camera. From all Montana slides in which the taxon occurred (Table 1), 19

K-NOVA141.indb 142 25.01.2012 07:04:21

eschweizerbart_xxx

143Fragilariforma horstii sp. nov.Ta

ble

1. L

ocal

ity, p

erce

ntag

e of

F.

hors

tii

valv

es, a

nd e

nvir

onm

enta

l da

ta f

or t

he s

ampl

es a

naly

zed

in t

he p

rese

nt s

tudy

. Use

d ab

brev

iatio

ns:

“AN

SP”

= D

iato

m H

erba

rium

, Aca

dem

y of

Nat

ural

Sci

ence

s Ph

ilade

lphi

a; “

Phyc

. Sec

t.” =

Phy

colo

gy S

ectio

n, P

atri

ck C

ente

r fo

r E

nvir

onm

enta

l R

esea

rch,

AN

SP;

″ N/A

” =

data

not

ava

ilabl

e; “

T”

= Te

mpe

ratu

re in

°C

; “C

ond.

” =

Con

duct

ivity

in µ

S.cm

–1; “

Tot.

N”

= To

tal n

itrog

en in

mg.

l–1; “

Tot.

P” =

Tot

al p

hosp

horu

s in

mg.

l–1, a

nd “

D. O

.” =

Dis

solv

ed o

xyge

n in

mg.

l–1.

Sam

ple

No.

/ L

ocat

ion

Riv

er /

Col

lect

ion

date

Loc

atio

n (L

at.,

Lon

g.)

% p

er

600

valv

esE

nv. d

ata

4152

01 /

Mon

tana

Col

lect

ion,

H

elen

aJo

hnso

n C

reek

, Bea

verh

ead

Cou

nty,

Mon

tana

/ Ju

l. 30

, 200

745

° 44′

31″

N, 1

13°

40′ 4

8″ W

1T

: 16.

3pH

: 7.6

Con

d.: 4

5To

t. N

: 0.

185

Tot.

P : 0

.012

D. O

.: 7.

7

4055

01 /

Mon

tana

Col

lect

ion,

H

elen

aA

tlant

ic P

ond,

Gla

cier

Nat

iona

l Par

k, M

onta

na /

Aug

. 14,

200

748

° 34

′ 17″

N, 1

13°

28′ 3

3″ W

1T

: 21.

1pH

: 6.9

8C

ond.

: 71

3819

01 /

Mon

tana

Col

lect

ion,

H

elen

aSw

amp

Cre

ek, S

ande

rs C

ount

y, M

onta

na /

Sep.

4, 2

006

47°

30′ 5

6″ N

, 115

° 01

′ 17″

W1

T: 1

8.3

pH: 6

.81

Con

d.: 9

1To

t. N

: 0.

010

Tot.

P : 0

.009

D. O

.: 8.

39

4148

01 /

Mon

tana

Col

lect

ion,

H

elen

aFi

shtr

ap C

reek

, Dee

r L

odge

Cou

nty,

Mon

tana

/ Ju

l. 26

, 200

745

° 53

′ 17″

N, 1

13°

16′ 0

6″ W

2T

: 16.

9pH

: 7.8

Con

d.: 7

4To

t. N

: 0.

130

Tot.

P : 0

.013

D. O

.: 7.

72

3761

01 /

Mon

tana

Col

lect

ion,

H

elen

aPa

radi

se S

prin

g B

rook

, Gla

cier

Nat

iona

l Par

k,

Mon

tana

/ Se

p. 9

, 200

748

° 28

′ 49″

N, 1

13°

22′ 3

1″ W

8N

/A

AN

SP, G

. C. 1

1036

8a

Phila

delp

hia

Litt

le K

ijik

Riv

er, L

ake

and

Peni

nsul

a B

orou

gh,

Ala

ska

/ Aug

. 24,

200

460

º 17

′ 08″

N, 1

54 º

20′ 3

5″ W

1T

: 6.5

pH: 6

.2C

ond.

: 56

Tot.

P: 0

.004

D. O

.: 10

.2

WE

MA

P091

0 / P

hyc.

Sec

t. Ph

ilade

lphi

aH

oodo

o C

reek

, Leh

mi C

ount

y, I

daho

/ A

ug. 1

6,

2004

45 º

05′ 3

1″ N

, 114

º 56

′ 21″

W<

1T

: 13.

2pH

: 6.6

Con

d.: 2

0To

t. P:

0.0

02

WE

MA

P122

4 / P

hyc.

Sec

t. Ph

ilade

lphi

aJo

ey R

amon

e C

reek

, Tet

on C

ount

y, W

yom

ing

/ A

ug. 3

1, 2

004

44 º

09′ 8

9″ N

, 110

º 73

′ 41″

W<

1T

: 12.

7pH

: 7.8

Con

d.: 4

0To

t. P:

0.0

15

K-NOVA141.indb 143 25.01.2012 07:04:21

eschweizerbart_xxx

144 E. A. Morales et al.

valves were selected and measured. Archived material and replicate slides have been deposited in the Montana Diatom Collection (MDC) in Helena, Montana and in the University of Montana Herbarium at Missoula. Relative abundances of diatom species are based on identifi cation and counts of 600 valves following the above SOPs. Data are stored in the Montana Diatom Data-base, which is maintained by L. Bahls.

The Idaho and Wyoming samples were collected as part of the United States Environmental Protection Agency’s Western Environmental Monitoring and Assessment Program (WEMAP). Water chemistry, physical habitat, landscape characteristics and biological data were collected from perennial streams/rivers in these two states and 10 others on the western United States fol-lowing methodology presented by Stoddard et al. (2005). Briefl y, periphyton samples from each site were collected at ¼, ½ or ¾ of the distance to the stream bank after a random start and for each of 11 transects. A surface area of 12 cm2 was scraped with a toothbrush from rock/wood substrates (erosional habitat). Soft sediments were vacuumed with a 60 mL syringe (depositional habitat). All 11 samples per reach were combined into one composite sample which was preserved with 37 % formalin. A subsample of 10 – 20 mL of each composite sample was acid-digested (Patrick & Reimer 1966), rinsed with distilled water and mounted using NAPHRAX® mounting medium. A minimum of 600 valves were counted and identifi ed to the lowest taxonomic level possible (mostly species) at 1000 X under a Leica DMLB™ microscope equipped with differ-ential interference contrast (DIC) and images were captured and measured using a Spot Insight QE Model No. 4.2 color digital camera. A total of 20 specimens were measured from samples in which the taxon was found (Table 1). Archived material and permanent WEMAP slides were deposited in the Diatom Herbarium, Academy of Natural Sciences of Philadelphia (ANSP) and the Phycology Section, Patrick Center for Environmental Research (PCER), ANSP.

Samples from Alaska were preserved with formaldehyde (4 % fi nal concentration) and ana-lyzed by the Phycology section, PCER, ANSP. Ecological data for the Little Kijik River, Alaska, chosen as the type locality of the new taxon described herein, are included in Brabets & Ourso (2006). Collection methods followed protocols developed for the United States Geological Sur-vey (USGS) National Water Quality Assessment Program (NAWQA) (Fitzpatrick et al. 1998, Moulton et al. 2002). For LM analyses of the Alaska sample, a sub-sample was digested with nitric acid using the microwave method, washed by rinsing and decanting with distilled water, and air-dried aliquots mounted on glass slides using NAPHRAX® (Charles et al. 2002). A Nikon Microphot-FXA microscope equipped with differential interference contrast (DIC) and a Spot Insight QE Model No. 4.2 color digital camera were used to measure and capture images of se-lected specimens. Archived material and permanent slides were deposited in the ANSP Diatom Herbarium or the PCER Phycology Section collection. Relative abundances of diatom species are based on identifi cation and counts of 600 valves following methodology in Charles et al. (2002). Data are stored in PCER Phycology Section’s North American Diatom Ecological Da-tabase (NADED). Forty valves were randomly selected and measured to obtain ranges in valve dimensions and striae density.

For SEM studies, aliquots of processed material were air dried onto 15 cm2 pieces of alumi-num foil. The foil was trimmed into smaller pieces and mounted on aluminum stubs with double-sided tape. The stubs were then coated with gold-palladium using a Polaron Sputter Coater for ca. 1.5 min at 1.8 kV. A Leo-Zeiss 982-DSM electron microscope was used for SEM analysis. Digital images were captured and plates were assembled using Adobe Photoshop CS4. Morpho-logical terminology follows Anonymous (1975), Ross et al. (1979), Williams & Round (1987) and Round et al. (1990).

K-NOVA141.indb 144 25.01.2012 07:04:21

eschweizerbart_xxx

145Fragilariforma horstii sp. nov.

Results

Fragilariforma horstii E. Morales, Manoylov & Bahls sp. nov. Figs 1–15 LM, 16 – 21 SEM

DESCRIPTIO: Frustula aspectu cingulari rectangularia partim visae ob gibbam centralem promi-nentem, catenas formantes per spinas. Valvae isopolares cruciatae apicibus gradatim anguste rostratis, 4 –15 µm longis, 4 –12 µm latis, 30-38 striae in 10 µm (n = 79). Sternum angustissimum rectum tenuum in microscopio photonico. Limbus valvaris abruptus margine parallelo ad valvae et limbi marginem ornamento carentis ad apices. Striae in quoque lato areae axialis valvae op-posite dispositae curvatae in superfi cie valvae plerumque radiantes ubique valvam. Striae unise-riatae aliquae continuae ex superfi cie ad limbum valvae sed nonnunquam interruptae per unam spinam locatam in valvae et limbi margine. Striae aliquae curtae non terminans in aream axialem valvae praesertim striae locatae in expansione centrali valvae. Volae non visae. Spinae solidae conicae spatulatae ad apices circumcinctae per annulos siliceos prominentiis. Spinae plerumque in costis sed nonnunquam secus striam in valvae et limbi margine. Costae elevatae tantum interne valvae ut striae alveiformes videtur. Areae porellarum aliquot porellis rotundatis in valvae et limbi juncture. Una portula in quoque valva rotundam sejunctam foramine formans stria repo-nens. Copulae latae non perforatae. Plastidi incogniti.

Figs 1–15. LM and SEM micrographs of Fragilariforma horstii sp. nov. 1– 6. LM images from type mate-rial, Little Kijik River, Lake and Peninsula Borough, Alaska. Notice the apparently closed girdle element in Fig. 6. 7–11. LM images from streams in Montana, U.S.A. 7. Johnson Creek, Beaverhead County. 8. Atlantic Pond, Glacier National Park. 9. Swamp Creek, Sanders County. 10. Fishtrap Creek, Deer Lodge County. 11. Paradise Spring Brook, Glacier National Park. 12. LM image of specimen from Hoodoo Creek, Lemhi County, Idaho. 13. LM image of specimen from Joey Ramone Creek, Teton County, Wyoming. 14. SEM image of type material showing an external view of the valve with characteristics of axial area, striae, spines, and apical pore fi elds. 15. SEM of type material showing an internal view. Notice depressed striae due to raised costae. Scale bars: 1–13: 10 µm, 14 –15: 2 µm.

K-NOVA141.indb 145 25.01.2012 07:04:21

eschweizerbart_xxx

146 E. A. Morales et al.

DESCRIPTION: Frustules rectangular in girdle view and only partially seen due to prominent central swelling, forming chains with the aid of spines (Figs 11, 16, 17). Valves isopolar, cruciform with narrowly rostrate, tapering apices (Figs 1– 5, 7–10, 12, 13). Length 4 –15 µm, breadth 4 –12 µm, striae density 30 – 38 in 10 µm (n = 79). Sternum very narrow and straight, faint in LM (Figs 1– 5,

Figs 16 – 21. SEM micrographs of Fragilariforma horstii sp. nov. from type material, Little Kijik River, Lake and Peninsula Borough, Alaska. 16. Detail of apex showing characteristics of areolae, spines, apical pore fi elds and valve mantle devoid of ornamentation at the very apex. 17. Detail of valve central expansion showing position of spines and short striae. 18. Internal view of apex denoting trough-like striae, raised costae, apical pore fi eld and isolated portula (arrow). 19. Valve interior with detached open girdle elements, devoid of ornamentation. Arrow indicates a ligula in one of the elements. 20. Internal detail of apex without portula. Notice thickness of valve at the edge of mantle. 21. Detail of other apex of the same valve depicted in Fig. 20 showing isolated portula (arrow) and the round poroids of the apical pore fi eld. Scale bars: 16: 0.5 µm, 17, 18, 20, 21: 1 µm, 19: 2 µm

K-NOVA141.indb 146 25.01.2012 07:04:22

eschweizerbart_xxx

147Fragilariforma horstii sp. nov.

7–10, 12, 13 and 14). Valve mantle steep (Figs 14 – 21) with edge parallel to the valve face/valve mantle border (Figs 14, 15) and devoid of ornamentation at the valve apices (Figs 14, 15). Striae on each side of valve axial area aligned opposite to one another, curved on valve face and mostly radial throughout the valve (Fig. 14). Striae uniseriate, some uninterrupted from valve face to valve mantle (Figs 14, 16), but some others interrupted by a spine located on the valve face/valve mantle edge (Fig 14). Some striae shorter and not ending at the valve axial area, especially those located in the valve central expansion (Figs 14, 15, 17, 19). Volae not seen. Spines solid, conical becoming spatulate at the ends, and surrounded at the base by a ring of silica with projections (Figs 14, 16, 17). Spines mostly on costae, but sometimes along a stria at the valve face/valve mantle edge (Figs 14, 16, 17). Costae raised only on the valve interior making striae appear as troughs (Figs 18 – 21). Apical pore fi elds present, with several round poroids irregularly disposed at the valve mantle (Figs 14 –16, 18, 21). One portula per valve and represented by a round hole, isolated, and located in the place where a striae would have developed (Figs 15, 18, 21). Girdle bands wide, without perforations (Fig. 19). Plastids not observed.

HOLOTYPE: Here designated as slide ANSP G. C. 110368 a, Diatom Herbarium, Academy of Natural Sciences, Philadelphia (ANSP). Sample collected by T. Brabets, United States Geologi-cal Survey, Water Research Division Alaska, August 24, 2004.

ISOTYPE: Slide HCUCB D-5, Herbario Criptogámico Universidad Católica Boliviana, Cocha-bamba, Bolivia.

TYPE LOCALITY: Little Kijik River above Kijik Lake near Port Alsworth, Lake and Peninsula Bor-ough, Alaska, USA. Lat. 60° 17′ 08″. Long. 154° 20′ 35″.

ETYMOLOGY: The new species is dedicated to Prof. Dr. Horst Lange-Bertalot for his devotion to diatoms and outstanding contributions to their knowledge.

ECOLOGY: Most of the streams included in the present manuscript have slow fl owing waters, sug-gesting an adaptation of the new taxon to this condition. The new taxon was not abundant in the sample chosen as the type, reaching only 1 % of the total periphyton community encountered in a 600 valve count (Table 1). The dominant accompanying species are Tabellaria fl occulosa (Roth) Kütz. (32 %), Synedra rumpens Kütz. (19 %), Fragilaria vaucheriae (Kütz.) J. B. Petersen (6 %), Achnanthidium jackii Rabenh. (5 %), and Stauroforma exiguiformis Flower, V. J. Jones & Round (3 %). Table 1 shows that all the sites for which the new taxon was reported have cold waters with very low nutrient content and low conductivity. The pH ranges from 6.2 to 7.9, indicating that the taxon does not only thrive in acidic waters, but it can survive in basic conditions. Table 1 also shows that Paradise Spring Brook, Glacier National Park, Montana contains the highest abundance of the new taxon Fragilariforma horstii, but environmental data were not collected for this site.

Discussion

The accompanying taxa cited above for the type sample, except Fragilaria vaucheriae, are com-monly reported as circumneutral to acidophilous diatoms thriving in oligo to mesotrophic wa-ters (Whitmore 1989, Van Dam et al. 1994, Watanabe & Asai 1999, Rakowska 2001, Siver et al. 2004). Fragilaria vaucheriae is an alkaliphilous, eutraphentic taxon (Van Dam et al. 1994), but its presence in the Little Kijik River, type locality for Fragilariforma horstii, is not surprising since the sample contains other taxa with the same ecological requirements, for example, Di-atoma tenuis C. Agardh and Planothidium haynaldii (Schaarschm.) Lange-Bert. The presence of these latter taxa indicate infl ux of important amounts of nutrients most probably due to massive

K-NOVA141.indb 147 25.01.2012 07:04:23

eschweizerbart_xxx

148 E. A. Morales et al.

Tabl

e 2.

Com

pari

son

of F

ragi

lari

form

a ho

rsti

i sp.

nov

with

oth

er ta

xa in

Fra

gila

rifo

rma

havi

ng a

cru

cifo

rm s

hape

.

Spec

ies

Shap

e / M

orph

omet

rics

Cen

tral

ste

rnum

/ St

riae

Spin

esA

pica

l por

e fi e

ld /

port

ula

Gir

dle

band

sR

efer

ence

/ N

ote

Fra

gila

rifo

rma

fl ori

dana

(H

anna

) D

. M. W

illia

ms

Cru

cifo

rm w

ith b

road

ly

roun

ded,

sub

capi

tate

ap

ices

/ L

: 17–

47, W

: 10

–19,

Str

/10

µm: 1

3 – 21

Obv

ious

in S

EM

at e

nd p

oles

and

in

tern

ally

/ Si

ngle

row

of

roun

d po

res

from

axi

al a

rea

to v

alve

fa

ce e

dge.

Sho

rt s

tria

e at

mid

dle

infl a

tion.

Hya

line

area

aro

und

valv

e fa

ce p

erim

eter

pre

sent

in

som

e po

pula

tions

. Str

iae

rece

ssed

in

inte

rnal

SE

M v

iew

Tub

ular

with

spa

tula

te

ends

, alo

ng v

alve

fac

e ed

ge

incl

udin

g ap

ices

. All

abou

t th

e sa

me

size

. No

ring

of

silic

a at

the

base

.

Abs

ent b

ut h

avin

g a

grou

p of

den

sely

pa

cked

str

iae

in th

eir

plac

e / A

bsen

t

Ope

n, li

gula

te

with

sca

ttere

d ar

eola

e in

par

s in

teri

or a

nd

exte

rior

Met

zelti

n &

Lan

ge-

Ber

talo

t 200

7,

Will

iam

s 19

90

Fra

gila

rifo

rma

ham

ilto

nii

Met

zelti

n &

Lan

ge-B

ert.

Cru

cifo

rm, b

ut m

ore

com

mon

ly r

hom

bic

and

with

cun

eate

api

ces

/ L

: 6.5

– 44

, W: 4

.4 –1

2,

Str/

10 µ

m: 1

8 – 22

Fain

t in

LM

/ Si

ngle

row

of

roun

d po

res

from

axi

al a

rea

to a

di

stan

ce f

rom

val

ve f

ace

edge

. N

o sh

ort s

tria

e re

port

ed. H

yalin

e ar

ea a

roun

d va

lve

face

per

imet

er

wid

e. R

eces

sed

natu

re o

f st

riae

no

t rep

orte

d

Stru

ctur

e no

t defi

ned

, sm

all,

alon

g va

lve

face

edg

e,

pres

ence

on

valv

e ap

ices

not

re

port

ed. N

o ri

ng o

f si

lica

at

the

base

rep

orte

d

Not

rep

orte

d / N

ot

repo

rted

Not

rep

orte

dM

etze

ltin

& L

ange

-B

erta

lot 2

007

/ No

SEM

ava

ilabl

e

Fra

gila

rifo

rma

hors

tii

sp. n

ov.

Cru

cifo

rm w

ith n

arro

wly

ro

unde

d, r

ostr

ate

apic

es

/ L: 4

–15,

W: 6

–12,

St

r/10

µm

: 30 –

38

Fain

t or

invi

sibl

e in

LM

, obv

ious

in

SE

M /

Sing

le r

ow o

f ro

und

pore

s fr

om a

xial

are

a to

val

ve

man

tle. S

hort

str

iae

at m

iddl

e in

fl atio

n. H

yalin

e ar

ea a

roun

d va

lve

face

per

imet

er a

bsen

t. St

riae

rec

esse

d in

inte

rnal

SE

M

view

Solid

with

spa

tula

te e

nds,

al

ong

valv

e fa

ce e

dge

exce

pt

the

apic

es. A

ll ab

out t

he

sam

e si

ze. H

avin

g a

ring

of

silic

a w

ith r

adia

l ext

ensi

ons

at th

e ba

se

Pres

ent,

com

pose

d of

se

vera

l rou

nd p

oroi

ds /

Pres

ent,

but n

ot la

biat

e si

tuat

ed w

ere

a st

ria

wou

ld h

ave

deve

lope

d

Ope

n, li

gula

te,

alth

ough

som

e cl

osed

ele

men

ts

have

bee

n se

en

in L

M. N

o ar

eola

tion

Pres

ent w

ork

K-NOVA141.indb 148 25.01.2012 07:04:23

eschweizerbart_xxx

149Fragilariforma horstii sp. nov.

Tabl

e 2

(con

tinue

d).

Spec

ies

Shap

e / M

orph

omet

rics

Cen

tral

ste

rnum

/ St

riae

Spin

esA

pica

l por

e fi e

ld /

port

ula

Gir

dle

band

sR

efer

ence

/ N

ote

Fra

gila

rifo

rma

spin

ulos

a (P

atri

ck)

Met

zelti

n &

L

ange

-Ber

t.

Cru

cifo

rm w

ith b

road

ly

roun

ded,

sub

capi

tate

ap

ices

/ L

: 21–

41, W

: 11

–19,

Str

/10

µm: 1

4 – 20

Fain

t eve

n in

SE

M /

Sing

le r

ow

of r

ound

por

es f

rom

axi

al a

rea

to

a di

stan

ce f

rom

val

ve f

ace

edge

. Sh

ort s

tria

e at

mid

dle

infl a

tion.

H

yalin

e ar

ea a

roun

d va

lve

face

pe

rim

eter

nar

row

. Rec

esse

d na

ture

of

stri

ae n

ot r

epor

ted

Tub

ular

nat

ure

not r

epor

ted.

L

onge

r at

mid

dle

infl a

tion,

w

ith s

patu

late

end

s an

d al

ong

valv

e fa

ce e

dge

incl

udin

g th

e ap

ices

. No

ring

of

sili

ca a

t the

bas

e

Abs

ent,

but h

avin

g a

grou

p of

den

sely

pa

cked

str

iae

in th

eir

plac

e / N

ot r

epor

ted

Not

rep

orte

dM

etze

ltin

&

Lan

ge-B

erta

lot

2007

, Pat

rick

194

0 / V

alve

inte

rior

in

SEM

unk

now

n

Fra

gila

rifo

rma

stev

enso

nii M

etze

ltin

&

Lan

ge-B

ert.

Cru

cifo

rm w

ith r

ostr

ate

apic

es /

L: 1

3 – 86

, W:

8 –17

, Str

/10

µm: 1

6 –19

Invi

sibl

e in

LM

/ Si

ngle

row

of

roun

d po

res

from

axi

al a

rea

to

valv

e fa

ce e

dge.

Sho

rt s

tria

e at

m

iddl

e in

fl atio

n. H

yalin

e ar

ea

arou

nd v

alve

fac

e pe

rim

eter

na

rrow

. Rec

esse

d na

ture

of

stri

ae

not r

epor

ted

Tub

ular

nat

ure

not r

epor

ted.

L

onge

r at

mid

dle

infl a

tion,

al

ong

valv

e fa

ce e

dge

incl

udin

g th

e ap

ices

. No

ring

of

sili

ca a

t the

bas

e re

port

ed

Not

rep

orte

d / N

ot

repo

rted

Not

rep

orte

dM

etze

ltin

& L

ange

-B

erta

lot 2

007

/ No

SEM

ava

ilabl

e

Fra

gila

rifo

rma

wil

liam

sii

Met

zelti

n &

Lan

ge-B

ert.

Cru

cifo

rm w

ith r

ostr

ate

apic

es /

L: 1

0 –10

0, W

: 8 –

18, S

tr/1

0 µm

: 12 –

14

Fain

t or

invi

sibl

e in

LM

, onl

y ob

viou

s at

end

s in

SE

M /

Sing

le

row

of

roun

d po

res

from

axi

al

area

to a

dis

tanc

e fr

om v

alve

fa

ce e

dge.

Sho

rt s

tria

e at

mid

dle

infl a

tion.

Hya

line

area

aro

und

valv

e fa

ce p

erim

eter

wid

e. S

tria

e re

cess

ed in

inte

rnal

SE

M v

iew

Tub

ular

nat

ure

not r

epor

ted.

L

onge

r at

mid

dle

infl a

tion,

al

ong

valv

e fa

ce e

dge

exce

pt

the

apic

es. N

o ri

ng o

f si

lica

at th

e ba

se

Pres

ent,

but r

educ

ed,

conf

used

with

den

sely

pa

cked

str

iae

at a

pice

s / P

ortu

lae

not o

bser

ved

Not

rep

orte

dM

etze

ltin

& L

ange

-B

erta

lot 2

007

K-NOVA141.indb 149 25.01.2012 07:04:23

eschweizerbart_xxx

150 E. A. Morales et al.

sockeye salmon migrations into nearby Lake Clark and subsequent spawning in lake tributaries, including the Little Kijik River (Brabets & Ourso 2006).

Although SEM confi rmation is pending, F. horstii seems to have been reported in the literature before, but as unknown taxon collected from the Yellowstone National Park (Krammer & Lange-Bertalot 1991, p. 489, Plate 129, fi g. 9). The single LM micrograph presented by Krammer & Lange-Bertalot illustrates a specimen with the same overall shape, central sternum and striae characteristics as those of valves discussed above. The location of the Yellowstone National Park (States of Wyoming, Idaho and Montana) also corresponds to the area from where several of the populations presented herein are reported.

Fragilariforma horstii has several features that justify its placement in Fragilariforma: the uniseriate striae are recessed between thickened costae in valve interior view and are composed of simple round areolae, the position of spines mostly on the costae and at the valve face/mantle junction, the presence of a portula along a stria, the developed apical pore fi elds, and the ligulate, open girdle bands are characteristics also present in taxa currently placed in this genus (Wil-liams & Round 1987, Round et al. 1990, Williams 1990, 1996, Kingston et al. 2001, Metzeltin & Lange-Bertalot 2007).

The new species has three features that readily distinguish it from species in Fragilariforma:1) Presence of a ring at the base of the conical spines (Figs 14, 16, 17). The ring leaves a space

between its internal perimeter and the base of the spine making the latter appear as suspended from the valve surface. This basal ring sometimes has protrusions extending its area of contact with the valve face. There does not seem to be a pattern to the production of these extensions. Fragilariforma horstii has solid spines as revealed by broken off tips (Fig. 14). The protologue of the genus and of several Fragilariforma species state that spines are tubular, but the published SEM material does not show this clearly for all species. In the case of at least F. cassieae Kilroy & Bergey, F. rakiuriensis Kilroy & Sabbe (Kilroy et al. 2003), the spine interior seems to possess a softer core, but not an internal chamber, as it seems to be the case of F. virescens (the generi-type, Williams & Round 1987), F. fl oridana (Williams 1996), and F. platensis D. M. Williams (Williams 1996).

2) The portula lacks a labiate structure in its valve interior opening (Figs 15, 18, 21). This opening appears as an enlarged areola and it is situated where a stria should have developed. This is evidenced by a very short stria placed at the valve margin on the side where the portula develops. The stria on the other side of the axial area develops normally. The external opening of the portula is the same size of an areola, thus it is diffi cult to distinguish it in valve outer views. It is worth noticing that from all taxa with published SEM illustrations some species produce large rimoportulae, while others such as F. acidobiontica (Charles) D. M. Williams & Round show a rimoportula with much reduced labia (Charles 1986). Thus, the portula in F. horstii could be part of an apparent continuum in the development of portulae across Fragilariforma taxa. The rimo-portula in F. platensis is especially large (Williams 1996). Since in the latter is a fossil taxon and the rimoportula is embedded in the apical pore fi elds, it is possible that the reduced portula and its independence from the apical pore fi eld in F. horstii is a derived and more recent character in evolutionary terms. This possibility merits further research as does the possession of two rimo-portulae (one at each apex) by F. bicapitata (Ant. Mayer) D. M. Williams & Round (Krammer & Lange-Bertalot 1991) and the loss of the portulae altogether by F. cassieae and F. rakiuriensis (Kilroy et al. 2003).

3) Lack of perforations in the girdle bands. The literature reports a single row of areolae for girdle elements. This row is located on the pars interior of the elements, the place of contact with the adjacent girdle band. F. fl oridana has been reported to have scattered areolae on the girdle band pars interior and exterior (Williams 1990). Thus, it seems that also this character is variable among species of Fragilariforma. Open girdle elements were observed in F. horstii during SEM analyses (Fig. 19), however, some closed bands were observed, although infrequently, in LM

K-NOVA141.indb 150 25.01.2012 07:04:24

eschweizerbart_xxx

151Fragilariforma horstii sp. nov.

preparations (Fig. 6). More studies are needed to determine if all these are indeed open girdle ele-ments or if there could be open and closed girdle elements composing the cingulum as reported for other araphid taxa (Morales 2006). It is worth mentioning that observation of girdle bands in the type preparation was diffi cult due to presence of other araphid taxa in Fragilaria, Diatoma Bory and Synedra Ehrenb. Figure 19 is one of the few images we could gather showing girdle bands still in contact with a valve, although two extraneous perforated bands –albeit eroded- can be seen lying on the specimen.

Table 2 contains a comparison of F. horstii with other species in Fragilariforma having a cruciform shape F. fl oridana, F. hamiltonii, F. spinulosa, F. stevensonii, and F. williamsii all have this overall shape, but differ from F. horstii by being larger, broader, having a hyaline area around the valve face perimeter, more prominent apical pore fi elds, multiareolated girdle bands, etc. Some of these species also lack a defi ned axial area, portulae, and a ring at the base of the spines (Metzeltin & Lange-Bertalot 2007, Williams 1990). Additionally, F. horstii has a very high striae density (30 – 38 per 10 µm), much higher than that reported for all other taxa having a cruciform shape (Table 2).

Another set of species that produce variants with cruciform shape are F. cassieae, F. hun-garica var. tumida (Cleve-Euler) P. B. Hamilton, F. lata, F. lata var. acuta Flower, F. polygonata (Cleve-Euler) Kingston, Sherwood & Bengtsson, F. rakiuriensis, F. virescens. However, all of these diatoms produce constricted or biconstricted forms toward the large end of their size spec-trum (Renberg 1977, Williams & Round 1987, Kingston et al. 2001, Kilroy et al. 2003), a feature not present in studied F. horstii individuals.

The vela within the areolae of F. horstii could not be observed. It is possible that due to the small size of the areolae the vela are very delicate and thus easily lost during preparation. Incidentally, this structure has not been illustrated for the majority of taxa for which there is available published SEM micrographs. Williams & Round (1987) presented a micrograph of the valve surface of F. strangulata (Zanon) D. M. Williams & Round showing very fi ne membranes covering the entrance of the minute areolae. Also, Charles (1986) showed similar structures for F. acidobiontica.

Fragilariforma horstii sometimes produces mantle plaques along the valve mantle margin (Fig. 16). The production of these structures seems to be more constant in other species such as F. virescens (Williams & Round 1987), while others seem to lack them altogether as is the case of F. fl oridana (Williams 1990). The latter species and F. horstii, however, have a thick rim along the mantle edge (see arrows in Fig. 14) suggesting that the plaques develop to form a continuous layer of silica around the whole valve perimeter. Micrographs presented by Metzeltin & Lange-Bertalot (2007) for F. fl oridana show that this thickening is accentuated by a row of verrucae, depositions of silica material seen as whitish granules under SEM. The production of verrucae is not mentioned for most taxa in Fragilariforma, but it seems that these structures are rather common in some taxa such as F. spinulosa and F. fl oridana, in which their growth is profuse, especially at the valve apex and mantle (Williams 1990, Metzeltin & Lange-Bertalot 2007).

Acknowledgements

EAM thanks Dr. Marie Cantino and Jim Romanow from the Electron Microscopy Laboratory at the University of Connecticut for their help and constant support during SEM analyses, and Dr. Donald Charles from the Phycology Section, PCER, ANSP for continued support and funding provided for these analyses. Dr. Saúl Blanco, Universidad de León, Spain, kindly provided the Latin translation of the protologues. Samples and environmental data from Alaska were collected by United States Geological Survey, Water Research Division Alaska. LLB thanks Rosie Sada de Suplee and Jolene McQuillan, Montana Department of Environmental Quality, for providing

K-NOVA141.indb 151 25.01.2012 07:04:24

eschweizerbart_xxx

152 E. A. Morales et al.

samples and environmental data used in this study. Luc Ector, Public Research Centre-Gabriel Lippmann, Luxembourg and an anonymous reviewer are deeply thanked for their comments and improvement of the manuscript.

References

Anonymous (1975): Proposals for a standardization of diatom terminology and diagnoses. – Nova Hed-wigia Beih. 53: 323 – 354.

Brabets, T. P. & R. T. Ourso (2006): Water Quality, Physical Habitat, and Biology of the Kijik River Basin, Lake Clark National Park and Preserve, Alaska, 2004 – 2005. – U. S. Geol. Surv., Sci. Investigations Rep. 2006-5123. 52 pp.

Charles, D. F. (1986): A new diatom species, Fragilariforma acidobiontica, from acidic lakes in notheast-ern North America. – In: Smol, J. P., R. W. Battarbee, R. B. Davis & J. Meriläinen (eds), Diatoms and lake acidity, pp. 35 – 44. Dr. W. Junk Publ., Dordrecht.

Charles, D. F., C. Knowles & R. S. Davis (eds), (2002): Protocols for the Analysis of Algal Samples Col-lected as Part of the US Geological Survey National Water-Quality Assessment Program. – Acad. Nat. Sci. Philadelphia Patrick Center for Environm. Res.–Phycol. Section, Rep. no. 02 – 06. 124 pp.

Fitzpatrick, F. A., I. R. Waite, P. J. D’arconte, M. R. Meador, M. A. Mauplin & M. E. Gurtz (1998): Re-vised Methods for Characterizing Stream Habitat in the National Water-Quality Assessment Program. – U. S. Geol. Surv. Water Res., Investigations Rep. 98-4052. 67 pp.

Flower, R. J. (2005): A taxonomic and ecological study of diatoms from freshwater habitats in the Falkland Islands, South Atlantic. – Diatom Res. 20: 23 – 96.

Hustedt, F. (1952): Neue und wenig bekannte Diatomeen. IV. – Bot. Not. 1952: 366 – 410.Kilroy, C., K. Sabbe, E. A. Bergey, W. Vyverman & R. Lowe (2003): New species of Fragilariforma (Bacil-

lariophyceae) from New Zealand and Australia. – New Zealand J. Bot. 41: 535 – 554.Kingston, J. C., A. R. Sherwood & R. Bengtsson (2001): Morphology and taxonomy of several Fragi-

lariforma taxa from Fennoscandia and North America. – In: Economou-Amilli, A. (ed.), Sixteenth In-ternational Diatom Symposium, 25 Aug.–1 Sept. 2000, Athens & Aegean Islands, Greece, pp. 73 – 88. University of Athens, Greece.

Krammer, K. & H. Lange-Bertalot (1991): Bacillariophyceae 3. Centrales, Fragilariaceae, Eunotiaceae. – In: Ettl, H., J. Gerloff, H. Heynig & D. Mollenhauer (eds), Süsswasserfl ora von Mitteleuropa 2/3: 1– 576. G. Fischer Verlag, Stuttgart.

Metzeltin, D. & H. Lange-Bertalot (2007): Tropical diatoms of South America II. Special remarks on bio-gegraphic disjunction. – Iconogr. Diatomol. 18: 1– 877.

Morales, E. A. (2006): Staurosira incerta (Bacillariophyceae) a new fragilarioid taxon from freshwater systems in the United States with comments on the structure of girdle bands in Staurosira Ehrenberg and Staurosirella Williams et Round. – In: Ognjanova-Rumenova, N. & K. Manoylov (eds), Advances in Phycological Studies. Festschrift in Honour of Prof. Dobrina Temniskova-Topalova, pp. 133 –145. Pen-soft Publ., St. Kliment Ohridski Univ. Press, Sofi a-Moscow.

Moulton, S. R. Ii, J. G. Kennen, R. M. Goldstein & J. A. Hambrook (2002): Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program. – U. S. Geol. Surv., Open-fi le report 02-150, 75 pp.

Patrick, R. & C. W. Reimer (1966): The Diatoms of the United States: Vol. 1: Fragilariaceae, Eunotiaceae, Achnanthaceae, Naviculaceae. – Monogr. Acad. Nat. Sci. Philadelphia 13: 1– 688.

Rakowska, B. (2001): Indicatory values in ecological description of diatoms from Polish lowlands. – Int. J. Ecohydrol. Hydrobiol. 1: 481– 502.

Renberg, I. (1977): Fragilaria lata, a new diatom species. – Bot. Not. 130: 315 – 318.Ross, R., E. J. Cox, N. I. Karayevia, D. G. Mann, T. B. B. Paddock, R. Simonsen & P. A. Sims (1979):

An amended terminology for the siliceous components of the diatom cell. – Nova Hedwigia Beih. 64: 513 – 533.

Round, F. E., R. M. Crawford & D. G. Mann (1990): The diatoms. Biology and morphology of the genera. – Cambridge Univ. Press, Cambridge, 747 pp.

K-NOVA141.indb 152 25.01.2012 07:04:24

eschweizerbart_xxx

153Fragilariforma horstii sp. nov.

Simonsen, R. (1987): Atlas and catalogue of the diatom types of Friedrich Hustedt. – J. Cramer, Berlin, Stuttgart.

Siver, P. A., T. D. Ahrens, P. B. Hamilton, K. Stachura-Suchoples & J. P. Kociolek (2004): The ecology of diatoms in ponds and lakes on the Cape Cod peninsula, Massachusetts, U.S.A., with special refer-ence to pH. – In: Poulin, M. (ed): Seventeenth International Diatom Symposium 2002 Ottawa, Canada, pp. 335 – 357. Biopress Limited, Bristol.

Stoddard, J. L., D. V. Peck, S. G. Paulsen, J. Van Sickle, C. P. Hawkins, A. T. Herlihy, R. M. Hughes, P. R. Kaufmann, D. P. Larsen, G. Lomnicky, A. R. Olsen, S. A. Peterson, P. L. Ringold & T. R. Whittier (2005): An ecological assessment of western streams and rivers. – U. S. Environ. Prot. Agency, EPA 620/R-05/005. 66 pp.

Van Dam, H., A. Mertens & J. Sinkeldam (1994): A coded checklist and ecological indicator values of freshwater diatoms from The Netherlands. – Netherlands J. Aquatic Ecol. 28: 117–133.

Watanabe, T. & K. Asai (1999): Diatoms on the pH gradient from 1.0 to 12.5. – In: Mayama, S., M. Idei & I. Koizumi (eds), Proceedings of the Fourteenth Diatom Symposium 1996, pp. 383 – 412. Koeltz, Kö-nigstein.

Whitmore, T. J. (1989): Florida diatom assemblages as indicators of trophic state and pH. – Limnol. & Oceanogr. 34: 882 – 895.

Williams, D. M. (1990): Fragilaria fl oridana Hanna: Ultrastructure of the valve and girdle and its transfer-ence to Fragilariforma Williams & Round. – In: Ricard, M. (ed.), Ouvrage dédié à la Mémoire du Profes-seur Henry Germain (1903 –1989), pp. 259 – 265. Koeltz, Königstein.

Williams, D. M. (1996): Notes of the genus Fragilariforma (Fragilariophyceae: Bacillariophyta) with a description of a new Miocene fossil species, Fragilariforma platensis. – Nova Hedwigia Beih. 112: 283 – 288.

Williams, D. M. & F. E. Round (1987): Revision of the genus Fragilaria. – Diatom Res. 2: 267– 288.Williams, D. M. & F. E. Round (1988): Fragilariforma, nom. nov., a new generic name for Neofragilaria

Williams & Round. – Diatom Res. 3: 265 – 266.

K-NOVA141.indb 153 25.01.2012 07:04:24

eschweizerbart_xxx

K-NOVA141.indb 154 25.01.2012 07:04:24

eschweizerbart_xxx