Pugetia taxonomy

Taxonomy and Distinguishing Characteristics

Pugetia fragilissima

Kingdom: Protista

Division: Rhodophyta

Class: Florideophyceae

Order: Gigartinales

Family: Kallymeniaceae

Genus: Pugetia

Species: fragilissima

Pugetia firma

Kingdom: Protista

Division: Rhodophyta

Class: Florideophyceae

Order: Gigartinales

Family: Kallymeniaceae

Genus: Pugetia

Species: firma

Pugetia fragilissima was first described by H. Kylin in 1925. He collected his first samples in Puget Sound, Washington, and thus, named the genus "Pugetia." Later, in 1941 Kylin described Pugetia firma from samples found along the west coast of North America. He found enough similarities in morphology to group it within the same genus as Pugetia fragilissima. Subsequently Pugetia firma was moved into the genus Callophyllis by R. Norris in 1957 due to its reproductive structures, but then returned to Pugetia in 2004.

To learn more about the interesting history of Pugetia firma and the differences between the genuses Pugetia and Callophyllis, please click here: Callophyllis vs. Pugetia

Division Rhodophyta

Rhodophyta is a diverse division with ~ 4,000-6,000 species and ~675 genera. It is commonly referred to as the red algae or "the reds" and contains some of the most beautiful and complex algae in the world. It ranges from delicate species like Pugetia fragilissima, to small slimy species like Antithamnion, to tough calcium carbonate lined Calliarthron. Almost all of "the reds" are benthic marine species. Some have specialized to be epiphytic (growing on other algae) or even parasitic. The reds have a unique three part life history, which cycles between a gametangial plant, a carposporophyte and a sporangial plant. Interestingly, they lack a swimming stage and instead have unflagellated male gametes called spermatia. However, this has not stopped the reds from proliferating. Many red species can be found throughout the world's oceans. Most red algae photosynthesize the sun's energy for sustenance utilizing pigments, such as chlorophyll a, chlorophyll d, phycobilins and carotenoids. Red algae contain double layers of chloroplasts which lack endoplasmic reticulum. Within the chloroplasts are single unstacked thylakoids.

Class Florideophyceae

Florideophyceae is the largest class of red algae found in California and thus encompasses a huge range of diverse species. Despite the variety in form and function, they all share a few key features that are characteristic of Florideophyceae. Such traits include multicellular thalli, simple chloroplasts with phycobilin pigments, oogamous reproduction, and pit plugs. The cells are typically arranged in filaments, which can be branched, unbranched or aggregating.

Order Gigartinales

Gigartinales is an order filled with large beautiful red algae, some of which are economically valuable. Many morphological features of the Gigartinales are very similar to other orders such as the Cryptonemiales and the Rhodymeniales. Thus, reproductive anatomy is the most critical identifying characteristic for the order. All Gigartinales species have an auxiliary cell, which originated from a cortical cell. This auxiliary cell normally produces a gonimoblast with a few sterile filaments. Gigartinales have either a uniaxial or multiaxial construction

Family Kallymeniaceae

Kallymeniaceae is best known for its unique female reproductive system. Although there is some variation within the family, all algae in Kallymeniaceae have 3-celled carpogonial branches. Each supporting cell can bear one to may of these branches. The life cycle is haplodiplontic, with isomorphic life stages.The tetrasporophyte produces cruciate tetraspores. In terms of morphology, the family Kallymeniaceae is known for its multiaxial thalli which can be simple and undivided like in Pugetia or branched and cleft as in Callophyllis. Ordinarily it has a thin cortex (outer cell layer) and a much thicker medulla (inner cells) with large clear pseudoparachymatous cells and small filaments interspersed.

Genus Pugetia

The genus Pugetia has undergone many permutations as different criteria were used to characterize the genus. Currently the two most important features of the genus are the undivided blades and the presence of well-developed filaments interspersed in between the larger isodiametric medulla cells. The most closely related genus to Pugetia is Callophyllis. Although the branched thallus of Callophyllis clearly distinguishes it from Pugetia, many species of Pugetia, including P. firma were once classified as Callophyllis due to their female reproductive structure. With new molecular data, P. firma and other species have returned to Pugetia after being classified as Callophyllis for approximately 50 years.

To learn more about the interesting history of Pugetia firma and the differences between the genera Pugetia and Callophyllis, please click here: Callophyllis vs. Pugetia

Species fragilissima and firma

Considering the similar morphologies of Pugetia fragilissima and Pugetia firma, it can often be difficult to distinguish one from the other. Luckily, there are a number of tricks that can help phycologists differentiate them, both from the field and ultimately within the lab.

When observing these algae in their natural environment, habitat and basic morphology will be the most effective clues for deciphering their identities. Pugetia firma proliferates both in the low intertidal and the subtidal, whereas Pugetia fragilissima can only be found subtidally. Thus, if a specimen is found growing in the intertidal, it is more than likely Pugetia firma. The substrate upon which the alga is growing can also provide insight. Pugetia firma grows almost entirely on the side of rocks and although Pugetia fragilissima can also be found attached there, it can additionally grow on tubeworms or epiphytically on other red algae.

Both morphology and texture can be very informative, but sometimes deceiving traits. Pugetia fragilissima tends to have delicate undivided blades attached at the base, whereas Pugetia firma usually grows thicker cleft blades with a holdfast in the center. In intertidal specimens of Pugetia firma, large medulla cells are visible to the naked eye. Unfortunately, these morphological differences are only generalizations, not rules, and thus can potentially lead to a false classification.

The most revealing characteristicof these species lies within the medulla and thus, often a cross section of the blade is needed to positively identify Pugetia fragilissima from Pugetia firma. The small filaments within the medulla of Pugetia fragilissima are pigmented, however those in Pugetia firma are not. The pigmented filaments of Pugetia fragilissima are visible in the picture to the right.

Top

Pugetia fragilissima & Pugetia firma

Taxonomy and Distinguishing Characteristics