Dana, 1849
Diagnosis
No diagnosis is given because of the uncertainty currently prevailing over the taxonomic status of this supergenus. The position is further complicated in that Poulsen (1973) who carried out substantial revisions failed to designate type species for the new genera he proposed, although Martens (1979) did clear up the systematics of the genera he found in the South Pacific off Chile.
Conchoecia species groups
¥ daphnoides group; in the species of this group both rostra and the postero-dorsal corner of the carapace are developed into long processes. Characteristically shaped species. Right asymmetrical gland opens on the anterior margin of the carapace below the rostral incisure. This group equates to the genus Conchoecilla Claus, 1890.
¥ rotundata group; in the species of this group the left asymmetrical gland opens on, or close to the rostrum. Right asymmetrical gland opens closer to the antero-dorsal corner than to postero-dorsal corner. Right asymmetrical gland often difficult to see. Carapace height similar to breadth. This group equates to the genus Metaconchoecia.
¥ curta group; this group consists of small (<1.25 mm) globose species with carapace height only slightly less than the carapace length. Carapace often covered with a clear pattern of sculpturing. Sensory setae on first antenna bifid in both sexes. This equates to the genus Mikroconchoecia Claus.
¥ imbricata group; in the species of this group, the tubercles are developed on both carapace valves close to the postero-ventral corner. Carapace striking sculptured. Spines occur at the postero-dorsal corner. Rostra produced into sharp processes. This equates to the genus Conchoecissa Claus.
¥ gaussi group; species with large median gland openening at mid-length on ventral margin of both valves. This equates to the genus Gaussicia Poulsen, 1973.
¥ bispinosa group; this is a moderately sized group of species with a characteristically smoothly curved ventral margin to the carapace that curves smoothly into the posterior margin, and also lacks sculpturing. The distinguishing feature is that the "c" seta on the endopodite of the second antenna in both sexes is longer than the segment it is inserted on. This equates to the putative genus Orthoconchoecia Claus.
¥ borealis group; this group consists of large high latitude species (>2. 8mm), sometimes with sharp-edged shoulder vaults. Carapace is quite elongate tapering anteriorly, and often with a clear criss-cross pattern of striations over the anterior ventral region. The carapace glands open in the usual positions but there are a large number of supplementary glands just posterior to the asymmetrical gland on the right carapace valve. The frontal organ in the female is clearly differentiated into stem and capitulum and the stalk is segmented. The "e" seta on the first antenna is distally flattened in both sexes. In the male both the "a" and the "c" are quite long and the "b" and "d" setae carry supplementary armature. This equates to the putative genus Boroecia Poulsen.
¥ edentata group; this group has carapaces that are somewhat ovoid in shape with the ventral margin curving smoothly into the posterior margin. It is immediately recognisable from the large supplementary glands that open in the middle of the ventral margin. This group equates to the putative genus Gaussicia Poulsen, 1973.
¥ elegans group; this is a group of small to medium sized species (1-2 mm) with subrectangular carapaces that usually tapered anteriorly, and in some species carry spines at the posterior dorsal corner of the right valve. The carapace glands are located in the usual positions at the posterior ventral corner on the right valve and close to the posterior dorsal corner of the left valve. In the female the frontal organ is undifferentiated. In the male the characteristic feature is that the armature of the "e" seta consists of an oval patch of hairs. This group was considered by Poulsen to belong to the genus Paraconchoecia, but it was placed in a new genus by Martens (1979). This equates to the putative genus Discoconchoecia Martens.
¥ loricata groups; this group consists of medium to large-sized species with carapaces that taper anteriorly. They have supplementary carapace glands that lie laterally adjacent to the asymmetrical gland at the posterior ventral margin of the right carapace valve. This equates to the genus Loricoecia Poulsen.
¥ magna group; this is a group of medium-sized species lacking any spines at the posterior dorsal corner of the carapace or any elaboration of the rostrum. The lateral shape of the carapace is rectangular with the asymmetrical glands in their normal locations at the posterior ventral corner on the right carapace valve and close to the posterior dorsal corner of the left carapace valve. The frontal organ in the female is clearly differentiated into capitulum and stalk. In most species the armature on the "e"seta of the first antenna of the male consists of paired spinules distally that become alternate proximally. This equates to the genus Conchoecia sensu strictu Poulsen, 1973.
¥ mollis group; this is a group of large (>2.5 mm) species which are predominantly deep mesopelagic to abyssopelagic in their bathymetric ranges. The carapaces are subrectangular and carry a sculpturing of shallow to deeply incised striae over the anterior ventral region. There are large supplementary glands on both valves along the posterior margin of the carapace. In females the "a-d" setae on the first antenna are only about a third the length of the "e" seta, which is often flattened distally. In males the capitulum of the frontal organ is large and down-turned, the first antenna has "a" and "c" setae that are longer than the second segment of the limb, the "b" and "d" setae carry an extensive armature of spines and hairs, and the armature of the "e" seta consists of numerous paired spines and the seta is flattened distally. This group includes species that have been attributed to two putative genera Mollicia Poulsen, 1973 and Paramollicia Poulsen, 1973.
¥ obtusata group; this group of two species have rather ovoid carapaces with rounded posterior ventral dorsal corners and a marked sexual dimorphism in size. In the female the frontal organ is undifferentiated and on the first antenna the "a-d" setae are less than half the length of the "e" seta. In males the armature of the "e" seta of the first antenna consists of a relatively few pairs of spines that become alternating proximally. Another definitive characteristic is that the hook appendage on the endopodite of the right-hand second antenna is large, but that on the left-hand endopodite is reduced to a straight peg. The copulatory appendage is also unusually large in this species. This equates to the putative genus Obtusoecia Poulsen, 1973.
¥ procera group; this is a group of quite small species (<1.5 mm) in which the carapace tapers anteriorly, and in many species there is a small spine at the posterior dorsal corner of the right carapace valve. The carapace gland on the right carapace valve opens slightly anterior to the rounded posterior ventral corner. In females the frontal organ is straight and the capitulum is almost undifferentiated from the stalk, and the "e" seta of the first antenna is less than twice the lengths of the other setae. In the male the capitulum of the frontal organ is down-turned, and on the first antenna the "a" seta is longer than the second segment of the first antenna, the "c" seta is very short and the other setae are subequal. The armature of the "e" seta consists of pairs of long slender spines. This equates to the putative genus Proceroecia.
¥ spinifera group; this is a heterogeneous group in which the main distinguishing feature appears to be the long fine hairs on the proximal anterior margin of the "e"seta in females. Carapaces are generally sub-rectangular often tapering anteriorly. In some species the shoulder-vaults are sharp-edged, spines are present at the posterior dorsal corners of the right carapace valve in some, and there are supplementary tubercules just anterior to the posterior dorsal corner of other species. Similarly the armature of the "e" seta of the first antenna of the male, which generally consists of pairs of long spines, consists of rows of hairs in others. This equates to the putative genus Paraconchoecia.
¥ spinirostris group; this is a group of quite small species (<1.5 mm) with subrectangular-shaped carapaces that lack clear sculpturing. The carapace glands are located at their usual positions and there are no supplementary glands. In the female the frontal organ is straight and undifferentiated, and the first antenna has long hairs on the anterior margin of the "e" seta. In the male the frontal organ is differentiated and the capitulum if down-turned. On the first antenna the "a" seta is usually quite long, but the "c" seta is minute. The other setae are subequal with the "e" seta being very slightly longer than the others. The armature of the "e" seta consists of paired distal spines that become alternate proximally. This equates to the putative genus Porroecia.
[Adapted from Angel, 2000]