Achramorpha diomediae Hôzawa, 1918

Alvizu, Adriana, Xavier, Joana R. & Rapp, Hans Tore, 2019, Description of new chiactine-bearing sponges provides insights into the higher classification of Calcaronea (Porifera: Calcarea), Zootaxa 4615 (2), pp. 201-251 : 223

Achramorpha diomediae Hôzawa, 1918

Original description. Hôzawa 1918, p. 540, pl. 85, fig 10.

Type locality. Off Cape Rollin , Simushir Island, Kuriles. St. 4803, 418 m depth .

Synonym and citations. Achramorpha diomediae, Burton 1963, p. 93 .

Type material. [Cat. No. 1971, U.S. N.M.: one specimen] .

Material examined. BMNH-1938.7.4.72: one specimen and one slide, Swedish Bank, Zool. Inst. Acad. Sci. Leningrad. BMNH-1938.7.4.73: three specimens of different species, and one slide, Sea of Okhotsk, St. 214, Zool. Inst. Acad. Sci. Leningrad.

Remarks. Based on the original description, Achramorpha diomediae mainly differs from all other Achramorpha species due to the presence of an atrial skeleton composed of tetractines with their unpaired actines directed toward the base of the sponge ( Hôzawa 1918). Another difference is the absence of chiactines, which are not mentioned by Hôzawa (1918), and based on the spicule figures presented in the original description, this type of tetractines is not present in A. diomediae . In line with these characteristics, A. diomediae does not fit into the definition of the genus Achramorpha and should be excluded. However, the formal reallocation of this species to another genus requires an examination of the holotype.

The material analysed from the BMNH collection identified as A. diomediae also presents some incongruences. First, the material available in the collection is in two jars, the first one with one specimen (BMNH-1938.7.4.72) and the second (BMNH-1938.7.4.73) contains three different specimens with fairly distinctive morphology. Secondly, the slide from the specimen BMNH-1938.7.4.72 does not have chiactines in the atrial skeleton, presenting instead an atrial skeleton built up by tetractines with very long apical actines, similar to Breitfussia . Third, the slide of the specimen BMNH-1938.7.4.73, does not specify to which of the three specimens it belongs. Fourth, after examination of this second slide, we noticed that the skeletal arrangement is completely different than that in the slide of the specimen BMNH-1938.7.4.72. In summary, the samples available in the BMNH collection under the name A. diomediae are not Achramorpha , and should not be considered within this group of chiactines-bearing sponges.