Dictyopteris divaricata (Okamura) Okamura, 1932

Belleza, Dominic Franco C., Tateishi, Hiroto, Tanimae, Shin-Ichiro, Kobayashi, Taishun, Aota, Tomoyuki, Urasawa, Toshiki & Nishihara, Gregory N., 2025, An annotated list of brown seaweeds (Phaeophyceae) from Nakadori Island (northern Goto Islands, Nagasaki, Japan), Phytotaxa 694 (1), pp. 1-24 : 7

* Dictyopteris divaricata (Okamura) Okamura, 1932

Japanese name: エゾヤハズ (ezoyahazu)

Basionym: Haliseris divaricata Okamura, 1907

Syntype localities: —Cape Iwai, Kesen’numa Bay, Miyagi, Prefecture and Hakodate, Japan

Description and remarks: —This specimen is upright and 10 cm tall. The stipe is about 1.5 mm in diameter but is thinner and less robust as it extends as a midrib to each branch. Branching is dichotomous with obtuse apices. Reproductive sori occur as oblong to slightly elongate black spots and arranged as 2–3 rows on both sides of the midrib.

D. divaricata grows at 1–2 m on the leeward side of Yokoura’s rocky subtidal. This species is uncommon but can be found growing together with geniculate coralline algae and among other species of Dictyopteris such as D. prolifera and D. undulata in early spring. Previous collection records indicate that the distribution of this species was only found in Korea, China and in Japan’s northern island of Hokkaido and central part of the main island of Honshu and Shikoku ( Nagai 1940). However, this species may also be found in tropical regions ( Lastimoso & Santiañez 2021), suggesting a much broader temperature tolerance. This specimen may be a representative for its distribution in Japan’s southern Kyushu Island.

Material examined: —18ECS1-116-1