Hypnea nidulans Setch.

NEW YORK BOTANICAL GARDEN

"TT

Plants of Tutuila Island, Samoa

Collected by W. A. Setchei/l, under the auspices of the Division of
Marine Biology of the Carnegie Institution of Washington, D.O., Amred
6. Mayor, Director, June and July, 1920.

Hypnea nidulans s.. nov.

forming dense clumps anon?*
clusters of staghorn corals
(Aero;.ora phaeronis), Aua lieef
June I'2,1920

with tetrasPoran<ria

1084

No.

Plants of Tahiti, Society Islands

Collected by W. A. Setchell and H. E. Parks, under the auspices of
the Department of Marine Biology of the Carnegie Institution of Washington,
D. C., May, June, and July, 1922.

Hypnea nidulans Setchell

Reef at Tahara Mountain
June 18

no. 5186

Hypnea nidulans sp. nov. Fig. 30.

Frondibus laxe intricatis, cespitosis, in Acroporis phaeronis nidulantibus, 5-6 nun.
altis, decomposito ramosis, leviter compressis atrorubescentibus ; axi primario plus

H »

i - -

162

VEGETATION OF TUTUILA ISLAND.

minusve percurrente, alterne ramoso; ramis primariis longioribus et brevioribus,
ramosis aut simplicibus, apice abrupte attenuatis, acutis; cellulis internis magnis,
ad superficiem diminuendis, omnibus hyalinis, strato superficiali parvis cellulis
coloratis unistratosis composito; tetrasporangiis in nematheciis stricte delimitatis,
ephippioformibus infra apicibus ramulorum imponentibus, zonatim divisis, para-
physibus linearibus paucicellulatis commitatis; antheridiis cystocarpiisque ignotis.

No. 1084, forming dense clumps among clusters of staghorn corals (Acropora
phaeronis), Aua Reef (June 12, 1920, with tetrasporangia!).

Fig. 30.—Hypnea nidulans sp. nov. (No. 1084).

1.	Habit of portion of branches. X 1.33 +

2.	Portion showing position and shape of nemathecia. X 5.33+

3.	Enlarged tip of branch, forming a nemathecium. X 83.33 +

4.	Surface view of slightly crushed nemathecium to show tetrasporangia and paraphyses. X 333.33+

5.	Transverse section through a branch. X 333.33 +

This very distinct species has been distributed by Harvey (Friendly Island Algæ,
No. 44) as Hypnea pannosa J. Ag., which it certainly is not. It is one of the most
interesting of the pholadophytes of the reef moat. It usually nestles, or snuggles,
down under a compact mass of branches of staghorn coral, such as the natives
assemble and stack in low windrows in the reef moat for fish traps. Well down
in the pile, the Hypnea nidulans nestles in bunches in such fashion as to seemingly
avoid the extreme illumination. It is frequent on the Aua Reef and probably also
on the other exposed reefs.

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