Myelophycus caespitosus Kjellman, 1893

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 : 11-12

Myelophycus caespitosus Kjellman, 1893

Japanese name: ニシイワヒゲ (nishiiwahige)

Type locality: —Goto Islands, Nagasaki Prefecture

Description and remarks: —Specimens are bushy, with several individual terete unbranched thalli arising from a common point. Thalli are often twisted and can reach about 7 cm high with widths of 1–1.5 mm. Plants are common from early-late summer and can be found on the upper intertidal zone at Yokoura and Aokata and are attached to rocks via rhizoidal holdfasts.

This species was previously synonymized to Myelophycus simplex ( Papenfuss 1967) but was recently reinstated as a distinct species upon examining cox1 and cox3 DNA sequences ( Hanyuda et al. 2020). Their study shows that the distribution of M. simplex is distinct on the eastern coast of Honshu while M. caespitosus is distributed along the western coast of Honshu, Shikoku and Kyushu.

Material examined: —18ECS1-51 (1 to 4)

Family Petrospongiaceae