Polish Botanical Journal 55(1): 65–71, 2010 A NEW FRESHWATER GYROSIGMA (BACILLARIOPHYCEAE) SPECIES FROM HAWAII* JOHN PATRICK KOCIOLEK, CARRIE L. GRAEFF & REX L. LOWE Abstract. We describe here a new freshwater species of Gyrosigma from Kauai, Hawaii. The new species is angular, with straight and parallel sides and apices bent in opposite directions, 32–46 μm long and 5.5–7.0 μm wide. Gyrosigma krammeri sp. nov. possesses prominent depressions on either side of the external central area. Frustules are isomorphic with regard to the defl ection of the external proximal raphe ends, and otherwise possess the diagnostic features of the genus Gyrosigma. Taxa with similar morphology include an undescribed specimen from South America as well as G. moresbyana Reichardt from Papua New Guinea. The freshwater diatom fl ora of Hawaii appears to contain many undescribed taxa. Key words: biogeography, diatoms, freshwater, Gyrosigma, Hawaii, taxonomy, ultrastructure John Patrick Kociolek, Museum of Natural History, and Department of Ecology and Evolutionary Biology, University of Colo- rado, Boulder, CO 80309, U.S.A.; e-mail: [email protected] Carrie L. Graeff, Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, U.S.A. Rex L. Lowe, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, U.S.A. INTRODUCTION The freshwater diatom fl ora of Hawaii is not well these authors have not always seen eye-to-eye in documented. Hustedt (1942) described several their interpretation of features and taxa, they have species in his classic paper on freshwater dia- enlightened us as to the variability and ultrastruc- toms from several Pacifi c islands. More recently, ture of classic and new species of the genus. None fl oras published by Rushforth and his associates of these authors treated many freshwater species (Fungladda et al. 1983; Rushforth et al. 1984; from the tropics. McMillan & Rushforth 1985) recorded species In this paper we formally describe Gyrosigma that would be considered cosmopolitan. Reichardt krammeri Kociolek, Graeff & Lowe, sp. nov. as (2005) described a new Gomphonema Ehrenberg a species new to science from freshwater environ- from Hawaii, Massey (1978) a new Stauroneis ments in Hawaii, and detail its valve ultrastructure. species, and Main (2003) a new genus Diprora We discuss the systematic position of this species and and several new species from unique habitats. its possible implications for our understanding of the Sherwood (2004) summarized the literature up to origin of the Hawaiian freshwater diatom fl ora. 2003. Most recently, Lowe et al. (2009) and Lowe and Sherwood (in press) described new species of MATERIALS AND METHODS Achnanthes and Cosmioneis from wetwall habitats on Oahu and Maui, respectively. Material was collected from Lanai Stream, on the prop- The diatom genus Gyrosigma Hassall has re- erty of the McBryde Garden at the National Tropical cently received signifi cant attention (e.g., Stidolph Botanical Garden, South shore of Kauai, Hawaii, 29 July 1988, 1992, 1993, 1994; Sterrenburg 1990, 1992, 2009 (21°53′8.67″N, 159°29′33.04″W). 1993; Reid & Williams 2003; Reid 2004). Though Samples were cleaned by boiling in nitric acid. Cleaned valves were mounted on slides with Naphrax. * Dedicated to Dr. Kurt Krammer on the occasion of his 85th Light microscope observations were made with an birthday Olympus Bx-51 with the use of 63× (NA 1.43) and 100× 66 POLISH BOTANICAL JOURNAL 55(1). 2010 (NA 1.40) objectives, and digital images were taken with dinal rib. Central area bears two circular depressed an Olympus DP-71 digital camera. A JEOL JSM 6480 structures that are commonly but not always rela- LV was used for scanning electron microscopy. Cleaned tively large. Each branch of the raphe is S-shaped, material was air-dried on glass coverslips attached to with the external proximal ends defl ected opposite aluminum stubs. Stubs were coated with gold-palladium one another. External distal raphe end defl ected with a Cressington sputter coater operated at 8 Pa and opposite its corresponding proximal end. Striae 30 mA, providing ca 10 nm of coating. radiate about the center, parallel along most of The relative abundance of G. krammeri was deter- mined by three random 100 valve counts from slides of the length of the valve, to converge at the ends. the material and averaging the three counts. Transapical striae 30–32/10 μm; lengthwise striae 40–42/10 μm. Frustules isomorphic (having the same orientation of the raphe from one valve to RESULTS the other (Sterrenburg 1993). In SEM the valve exterior has two prominent Gyrosigma krammeri Kociolek, Graeff & Lowe, depressions in the ovoid to elliptical central area sp. nov. Figs 1–15 (Figs 7–10). Central area bears proximal raphe Valvae angulator, lateribus parallelis rectsi, angulator ends defl ected in opposite directions from one extremis a se adverso fl exiss apicibus rotundatis. Lon- another (Figs 8–10). The raphe transitions from gitudo 32–46 μm. Latitudo 5.5–7.0 μm. Area axialis a simple slit to becoming lateral, and the axial angusta unornata ad apicem, faciens aream centralem area widens towards the central area and the apices irregularem ad anguste ellipsoideam. Raphe margi- (Figs 8–11). At the distal ends the raphe ends are nata in uno latere costa longitudinali. Area centralis defl ected opposite one another, and opposite the depressibus 1–2 circularibus ut plerumque autem non corresponding proximal end (Fig. 11). The axial semper relative amplis. Rami raphis s-formi. Extrema area is bordered on one side by a row of slit-like proxiimales externi raphis deefl ecta opposita uno cetera. areolae that is more distant from the other striae Extrema distales externi raphis defl ecta opposita con- gruentes extrema proximales. Transapicales striae (Figs 9–11). The two central round to ovoid open- radiatae ad centro, parallelae fere longitudem valvis, ings may have a common chamber. Striae are com- convergentae ad apicibus, 30–32/10 μm, longitudinaliter posed of slit-like areolae externally, round to oval striae 40–42/10 μm. Frustulae isomorphicae. internally. Striae are radiate and curved around the center. Striae distant from the center become TYPE: HAWAII, Kauai, Lanai Stream at McBryde curved towards the center, then bend towards the Campus, National Tropical Botanical Garden. 29 July apex (Figs 9–11). External distal ends defl ected 2009, leg. J. P. Kociolek & C. L. Graeff [HOLOTYPE onto the valve mantle. A triangular unornamented (Fig. 4): Accession Number 744386, Herbarium of the area at the apex is bordered by striae, the raphe Bishop Museum of Natural History (BISH), Honolulu; end and a row of slits on the mantle (Fig. 11). ISOTYPES: Accession #627381; slide #223003, Diatom These have been termed ‘apical pores’ by Ster- Collection, California Academy of Sciences, (CAS), San Francisco]. renburg (1991). Internally the elevated axial area is bordered ETYMOLOGY: Named in honor of Kurt by longitudinally oriented ribs, more prominent Krammer, for his many and varied contributions on the primary side of the axial area than on the to diatom research, and on the occasion of his secondary side (Fig. 12). The ribs do not extend 85th birthday. all the way to the helictoglossae (Figs 12 & 13). Valves angular, with parallel, straight sides, The central nodule is ellipsoidal and contains the distal ends bent in opposite directions, and apices dilated proximal ends (Figs 14 & 15). The central rounded. Length 32–46 μm. Breadth 5.5–7.0 μm. nodule is bordered by arched thickenings, vari- Axial area narrow, unornamented at the apices and ously termed ‘central bars’ (e.g., Schrader 1973; forming an irregular to narrowly ellipsoidal central Sterrenburg 1991; Reid 2002; Reid & Williams area. Raphe bordered on one side by a longitu- 2003) or ‘crescentic thickenings’ (Stidolph 1993) J. P. KOCIOLEK ET AL.: A NEW FRESHWATER GYROSIGMA SPECIES FROM HAWAII 67 Figs 1–6. Gyrosigma krammeri Kociolek, Graeff & Lowe, sp. nov. Valve views showing size range; all LM. Scale bar = 10 μm. Figure 1 is of the holotype. and ‘apical costae’ (Stidolph 1988), which are it was found. While recent papers have begun to continuous with the longitudinal ribs (Figs 12, 14 demonstrate the unique nature of the Hawaiian & 15). The raphe terminates distally into helic- fl ora, a signifi cant amount of research is yet needed toglossae (Fig. 13). Internal openings of the areolae to document even the relatively common members appear rectangular (e.g., Fig. 14). of the freshwater diatom fl ora of Hawaii. Our observations on this Gyrosigma from Ha- waii suggest that while it has many similarities DISCUSSION with other members of the genus, it also has some A review of the classical monographs by Peragallo unique features. With other members of the Pleu- (1891), treatments of specifi c taxa by Reid and rosigmataceae Mereschkowsky, G. krammeri has Williams (2003) and Stidolph (1988, 1992, 1993) valves that are linear and parallel-sided, a sigmoid and Sterrenburg (1994, 1995, 2001), freshwater raphe system, and triangular hyaline areas at the fl oras by Krammer and Lange-Bertalot (1986) and apices of the valve externally (Sterrenburg 1991; Patrick and Reimer (1966), and previous fl oristic Stidolph 1988; Reid 2002; Reid & Williams 2003). work on Hawaii (Fungladda et al. 1983) failed to The presence of thickened ‘central bars’ around identify a species to which we could assign this the central area internally, and external proximal taxon. Thus, we continue to add to the knowledge raphe ends that are defl ected in opposite direc- of the freshwater diatom fl ora of Hawaii. This Gy- tions, are features also shared across members of rosigma species occurred with 26% relative abun- the genera Gyrosgima, Pleurosigma W. Smith and dance of the diatom fl ora in the sample in which Toxonidea Donkin. 68 POLISH BOTANICAL JOURNAL 55(1). 2010 The external proximal raphe ends of G. kram- The presence of large depressions or openings meri are variable. Sterrenburg (1993) described to a single depression is illustrated in ‘Gyrosigma two types of external proximal raphe ends in Gyro- spec. cf. scalproides (Rabenhorst) Cleve’ (Met- sigma; ‘crooks’ where the curvature of the raphe is zeltin & Lange-Bertalot 1998, Pl. 128, fi gs 3 and 4) smooth and round, and ‘hooks’ where the raphe is from South America, and ‘Gyrosigma (?nov.) spec.’ angular and bent to a nearly 90 degree angle (Ster- from Ecuador (Rumrich et al. 2000, Pl. 108, fi g. renburg 1993, Fig. 3a, b). ‘Hooks’ are reported by 5). Our specimens also appear to have a thick- Sterrenburg (1993) to occur in isomorphic species ened elongated rib running from the central bar on only, as in G. krammeri (an isomorphic taxon), and the primary side nearly to the helictoglossa. Also our observations confi rm this relationship. present is a rib that is signifi cantly less thickened Figs 7–11. Gyrosigma krammeri Kociolek, Graeff & Lowe, sp. nov. External valve views. 7 – Entire valve showing shape of valve, sigmoid raphe and central area with two depressions. Scale bar = 5 μm. 8–10 – Elliptical central area with two depressions and proximal raphe ends which are both ‘hooks’. Scale bars = 1 μm. 11 – Valve terminus showing defl ected distal raphe end, triangular hyaline area of the axial area and areolae at the very apex of the valve. All SEM. Scale bar = 1 μm. J. P. KOCIOLEK ET AL.: A NEW FRESHWATER GYROSIGMA SPECIES FROM HAWAII 69 Figs 12–15. Gyrosigma krammeri Kociolek, Graeff & Lowe, sp. nov. Internal valve views. 12 – Entire valve view showing elevated axial area bordered by a more distinct (top) and less distinct (bottom) rib. Scale bar = 5 μm. 13 – Terminus of the valve showing helictoglossa and elevated axial area bordered by a rib. Scale bar = 1 μm. 14 & 15 – Central area of the valve, with central area a slightly elevated disc bearing the dilated proximal raphe ends. The central nodule is bordered on both sides by central bars which are connected to the axial ribs. All SEM. Scale bars = 1 μm. but evident on the secondary side of the axial currently referred to Frustulia the ribs may be area and extending from the central bar, nearly entire, shortened, or even absent (unpublished reaching the helictoglossae, similarly to the thick- observations). ened rib on the opposite side of the axial area. Another species resembling G. krammeri These longitudinal ribs resemble the situation in is G. moresbyana Reichardt (Reichardt 1988), members of the Amphipleuraceae Grunow, where a rare freshwater species described from Papua thickened ribs on both sides of the axial area may New Guinea. Like G. krammeri, G. moresbyana is extend uninterruptedly from one helictoglossa to more angular and has nearly parallel sides instead the other (Round et al. 1990). In some species of being more smoothly sigmoid, has triangular, 70 POLISH BOTANICAL JOURNAL 55(1). 2010 unornamented areas at the apices, and appears to REFERENCES have rounded structures in the central area. Un- fortunately, Reichardt (1988) did not publish elec- FUNGLADDA N., KACZMARSKA I. & RUSHFORTH S. R. 1983. tron micrographs when presenting his new species. A contribution to the freshwater diatom fl ora of the Ha- waiian Islands. Biblioth. Diatomol. 2: 1–103. 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