Saccocamera, Grischenko & Gordon & Melnik, 2018

Grischenko, Andrei V., Gordon, Dennis P. & Melnik, Viacheslav P., 2018, Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion - Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining, Zootaxa 4484 (1), pp. 1-91 : 33

Saccocamera n. gen.

Type species. Saccocamera ampulla n. sp.

Etymology. Latin saccus, sac, and camera, chamber, alluding to the discrete sac-like form of the incubation chamber. Gender feminine.

Diagnosis. Colony squat, wart-like, with peristomes radiating around 1–2 calyciform areas occupied by alveoli. Peristomial rims typically with projections. Colony surface mostly granular. Gonozooid discrete, sac-like, narrowing to laterally facing ooeciostome, lacking surficial ribbing, alveoli or pores.

Remarks. Saccocamera n. gen. is established here for a small suite of deep-sea species that resemble Disporella Gray, 1848 , but differ in having simple lageniform, sac-like incubation chambers that do not ramify between autozooids, and which lack pores and structural features on their surface like ribbing and alveoli. Apart from the type species, newly described here from the CCZ, other species include Saccocamera minima ( Moyano, 1991) n. comb. from 1200–1800 m off northern Chile , Saccocamera minicamera ( Gordon & Taylor, 2010) n. comb. from 750–1181 m on the Chatham Rise, New Zealand, and Saccocamera minutissima ( Gordon & Taylor, 2010) n. comb. from 943–1097 m on the Chatham Rise.

Moyano (1991) had suggested that his new species Disporella minima might be accommodated within a new genus, but left the question open. Gordon & Taylor (2010) considered this possibility but reasoned that the small size and saccular nature of the gonozooid might be no more than a consequence of small colony size, i.e. large colonies have large incubation chambers, small colonies have small chambers. Additionally, the occurrence of the gonozooid on the surface of the colony instead of being embedded in it might also be associated with small colony size and limited growth—large species have the capacity for increase in colony thickness, such that frontal growth of kenozooidal chambers can be achieved relatively quickly, partially or wholly concealing gonozooid surfaces. However, the finding of yet another small, squat deep-sea species with a simple saccular incubation chamber that lacks pores (unlike Disporella ), or any surficial reticulation or chambers, strengthens the case for segregation of these species from Disporella . Unfortunately, the ancestrula is not known in any species of Saccocamera n. gen., but it is assumed to be adnate.

Moyano (1991) further believed that, if his new species were to be assigned to a new genus, then Disporella cookae David & Pouyet, 1986 would be congeneric. In fact, this species has a pedunculate colony form and large gonozooid very like that found in Alyonushka n. gen., Calyssopora n. gen. and Rallocamera n. gen., but differs from these in having smooth calcification and a different form of incubation chamber in relation to alveoli; its ooeciopore is virtually flush with the gonozooid surface. It either belongs to yet another new genus or might be accommodated in a stretched concept of Calyssopora . In having smooth calcification it is reminiscent of Dartevellopora neozelanica , but in that species the column is made up of peristomial tubes with occluded apertures.