Chamaesipho is a genus of four-plated notochthamaline barnacles in the Pacific Ocean limited to Australian/New Zealand temperate waters. They are intertidal in preference, and tend to form crowded columnar colonies. They can be identified in the field by having a four-plated wall, an unfused rostrum, and narrow opercular plates. Elminius, which also inhabits the same area, has four plates in its shell wall. However, in Elminius, the rostrum and rostrolatera are fused completely, and the compound rostrum receives the alae of the adjacent carinolaterals. In Chamaesipho, the unfused rostrum bears
Chamaesipho is a genus of four-plated notochthamaline barnacles in the Pacific Ocean limited to Australian/New Zealand temperate waters. They are intertidal in preference, and tend to form crowded columnar colonies. They can be identified in the field by having a four-plated wall, an unfused rostrum, and narrow opercular plates. Elminius, which also inhabits the same area, has four plates in its shell wall. However, in Elminius, the rostrum and rostrolatera are fused completely, and the compound rostrum receives the alae of the adjacent carinolaterals. In Chamaesipho, the unfused rostrum bears alae, and closely resembles the carina in appearance.
==Definition and Discussion== The primary shell wall is four plated, reduced from six by fusion of rostrolatera and carinolaterals during ontogeny. No sutural interfolding is observed. With age, all plate sutures become concrescent. The basis is membraneous. Opercular plates are deeply articulated, but do not fuse together. The scutum bears a visible lateral depressor pit, and a scutal adductor ridge which ranges from nearly absent/indistinct to rounded prominent. The tergum is pitted internally. There is no trace of a tergal spur, and the tergal depressor area is wide, with prominent crests.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).