Cryptostomata of Sargassum

Sargassum is an Atlantic species with unique blade shapes. Fresh specimens show regular cylindrical primary and secondary branches, terete blades, mutic vesicles, and longer, more slender male receptacles. Previously considered a member of the subgenus Phyllotrichia, Sargassum desfontainesii lacks distinctive features like distichous primary branches and linear, pinnately branched lower blades. It is suggested that this species should be placed in the subgenus Sargassum, section Malacocarpicae, subsection Cymosae. Certainly, the species is now considered a genuine member of the subgenus Phyllotrichia. Have you heard about Cryptostomata of Sargassum?

Cryptostomata of Sargassum

Morphology of Sargassum

The thallus of Sargassum is coarse and bushy, reaching a height of 135 cm. The main axis is terete, 2-6 mm in diameter, 5-12 mm long, and bears 3-5 major branches with flat axes, each 3-5 mm broad. Also, branching alternates in one plane at a spacing of 0.8-1.4 cm.  Branches of the second order range in length from 34 to 61 cm, while those of the third order range from 12.5 to 6.5 cm long.

  1. The phylloids at the base are coarse, oval, or oblong, measuring 8 cm long and 1.6-2 cm wide. They have serrated undulate borders, an asymmetric base, and a midrib that disappears below the apex.
  2. Also, the phylloids in the center are 3.5-6.7 × 1.6 cm.
  3. Some species of brown algae have structures known as cryptostomata (singular: cryptostoma).
    Some Fucus species have these anatomical characteristics, while Pelvetia canaliculata does not.
  4. Cryptostomata are different and dispersed over phylloids and vesicles. Vesicles are stalked, roundish, broadly ovate to ellipsoidal, 0.3-1.0 × 0.8-1.3 cm, with jagged wings in the bottom half of the vesicles. They are either complete or with an appendage on top. Talk flat, foliaceous, with an asymmetrical base and serrate borders.
  5. Their attachment via basal disc. Further, they grow on shallow intertidal and subtidal rocks, stones, and dead corals.
Cryptostomata of Sargassum

Image source: Titlyanov, E., Titlyanova, T., Li, X., & Huang, H. (2016). Common Marine Algae of Hainan Island (Guidebook). Coral Reef Marine Plants of Hainan Island, 75-228.

Cryptostomata of Sargassum

The Fucaceae’s morphology and cytology concerns revolve mostly around the sexual organs. The unique sunken structures in which they are borne, are known as conceptacles; the similarly submerged but sterile structures are known as cryptostomata; and the sporelings. Sargassum‘s cryptostoma develops gradually, following the conceptacle’s history. They are conceptacles: sterile chambers that produce only hairs. They are located on the lamina of the Fucus serratus. Also, they emit colorless tufts of hair.

Origin of Cryptostomata

  • The first cell forms near the apical cell of a leaf or vegetative branch. The first cell of the cryptostomata splits transversely, resulting in a two-celled structure.
  • The lowest cells divide lengthwise. Then the process results in a collection of three cells, comparable to the conceptacle stage.
  • The two bottom cells of this three-celled stage split longitudinally into one or more planes, resulting in a structure with four or five cells in the longitudinal section.
  • The tongue cell is prominently located in the center of this and subsequent structures. As the lowest cells of the two-celled stage divide longitudinally, the structure’s walls progressively grow.
  • Cryptostomta paraphyses develop alongside sexual organs in the conceptacle. The production of paraphyses by wall cells does not disrupt their ability to generate cryptostomata.

Cryptostomata are distributed across blades but can be found near the margins of larger blades. Cryptostomata are elliptical and measure 60-214 × 24-143 µm in diameter.Cryptostomata of Sargassum


The conceptacles and cryptostomata arise from a single flask-shaped cell that forms the complete structure. Cryptostomata of Sargassum are famous in the whole group of algae. The initial cell splits into two distinct segments: a big bottom cell that forms the conceptacle and cryptostomata walls, and an upper cell, the tongue cell, which may stay dormant, divide into a short filament, or degenerate. The conceptacle and cryptostoma share homologous structures. The stages of development in both structures are identical, from the emergence of comparable starting cells to the formation of paraphyses in cryptostomata and sexual organs in the conceptionacle. The paraphyses develop basipetally by dividing the lowermost cell in each structure.

Some cryptostomata have spermatocysts or degenerate equivalents. Cryptostomata likely originated from conceptacles with sterile sexual organs.


  1. Titlyanov, E., Titlyanova, T., Li, X., & Huang, H. (2016). Common Marine Algae of Hainan Island (Guidebook). Coral Reef Marine Plants of Hainan Island, 75-228.

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