Atlas of Atlantic Ostracods

Notes

294 Records

In his original description of Conchoecia rotundata, Müller (1891) reported a long and a short form. Iles (1953) analysing material from the Benguela Current off SW Africa also found two forms, which he described as separate species C. teretivalvata (short form) and the C. skogsbergi (long form). Iles used using Skogsberg’s (1920) description of the long form from the Southern Ocean as the definitive description for Conchoecia skogsbergi, so designated neither type material nor a type locality. Gooday (1981) substantially revised what he termed the ‘skogsbergi complex’, naming six new species that previously would have fallen within the original concept of long forms of ‘rotundata’. He retained the name C. rotundata for another species that better matched both Müller’s original description and localities. He also reported that in the Southern Ocean there are three size groups of specimens that were consistent with Skogsberg's description; indeed Skogsberg himself reported some large specimens. Granata and Caporiacco (1949) placed all Muller’s ‘rotundata group’ in a separate genus Metaconchoecia but as was customary with halocyprid taxonomists failed to designate a type species. This nomenclature was not universally adopted until much later when Poulsen (1973) applied it in his Dana Report. Technically the genus remained a nomen nudum until Kempf (1986) nominated M. rotundata as the type species (note this predates Kock’s (1992) designation of fowleri).

Large specimens of Metaconchoecia frequently occur at deep mesopelagic depths and these have been usually been referred to as M. skogsbergi. The size ranges we give below were for specimens collected at 600-700m in a single horizontal tow at Discovery station 9969 (59°S; 20°W south of the Polar Front), and are typical of the smaller of the size forms. Females of the larger forms can reach 1.8mm. It is predominantly a Southern Hemisphere species, with the majority of the records coming from latitudes <22°S. However, there have been occasional records from deep water in the Northern Hemisphere. Leung reported this species as being caught in samples collected from the Fletcher Ice Island between 54° and 61°N but without giving precise co-ordinates. Chavtur (1976) reported this species from several positions between 46°-55°N in the North Pacific but in 2003 described these specimens as new species. Angel (1968) reported a single female specimen collected in the Norwegian Sea at 65°N 20°W, which Gooday (1981) re-examined and concluded it was similar to, but not necessarily identical with Southern Ocean specimens. He therefore designated this specimen as aff. skogsbergi, and probably this name should be given to all specimens and records from the Northern Hemisphere until they can be critically re-examined. Chavtur and Angel (in press) are revising the systematics of the genus Metaconchoecia, designating several new genera within a new tribe Metaconchoeciinae.

At present all specimens from deep water in the North Atlantic should be regarded as aff. skogsbergi.

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