Streptostemon catenulum (N.L.Gardner) Komárek

• Region

  West Indies

• Country

  Puerto Rico

• Locality

  on rocks and earth about ten kilometers north of Utuado

• Coordinates

  18.359, -66.7045

• Distribution

  Map all specimens of this taxon

B° Afi , ,

THE NEW YORK BOTANICAL GARDEN

DARIUS OGDEN MILLS FUND

FRESHWATER ALGAE OF PORTO RICO
COLLECTED BY PROFESSOR N, WIL
Utuado March 5-6-^1915

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Determined by Francis Drouet

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Determined by Francis Drouet

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Scytonema catenulum sp. nov.

Plate 17, figure 34

Filaments densely aggregated into erect fascicles 1.5-2 mm.
long, more or less agglutinated by their gelatinous walls; 18-
26 m diam., sparsely branched; trichomes moniliform when old,

8-12 n diam., the greater diameter being at the apices, diminish-
ing gradually in the older parts, in some cases entirely vanish-
ing, at the same time the sheath increasing in thickness corre-
spondingly; cells compressed dolioform at the apices, becoming
suhspherical in the older parts, yellowish green to bright aeru-
ginous, homogeneous; cross-wall inconspicuous; heterocysts
compressed spherical to concave when old; sheath subgelatinous,
homogeneous, and hyaline when young, becoming indistinctly
lamellose and ocreate at the apices, and yellowish when mature,
roughened on the surface; branching mostly single toward the
apices, geminate in part below.

Growing on rocks about ten kilometers north of Utuado, no.

1556, type, and on earth, no. 1561.

This species of Scytonema is well marked by the character of
the cells combined with the indistinctly ocreate sheath. The
cells in the meristematic region are very short and dolioform.

As the growing region moves forward, the successive cells be-
come more and more spherical, the sheath thickening and push-
ing in between the cells and eventually, in many instances, com-
pletely separating them. As the successive cells diminish in
diameter, the sheath becomes correspondingly thicker, and lin-
ally many cells completely disappear.

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: 34. Scytonema catenation

Apical portions of two filaments.

x 250

Determined by Francis Drouet

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