Atlas of Atlantic Ostracods
Taxon details
Alacia alata alata (Müller, G.W., 1906)
- Order:
- MYODOCOPA
- Suborder:
- Halocypridina
- Family:
- Halocyprididae
- Subfamily:
- Conchoecinae
- Size range (females):
- 1.9-2.4 mm
- Size range (males):
- 1.7-2.0 mm
- Depth:
- mesopelagic
Notes
203 records
This is a distinctively shaped species; its broadly winged shoulder vaults are a unique feature in Atlantic halocyprids. Poulsen (1973) established the genus Alacia to include all species in Müller’s “alata” group, which are characterized by having lateral corner glands on the posterior margins both valves. The likely function of these glands is to release bioluminescent secretions into the exhalent flow. The shoulder vaults in A. alata are also lined with glands that produce luminescence, but the luminescence is retained within the gland cells. The present genus is almost certainly artificial and will need to be split up. Poulsen (1973) failed to designate a type species for the genus, but the designation of this species would be appropriate. The bathymetric profiles show that this is generally a shallow mesopelagic species, which at times undertakes strong diel vertical migration and has been caught in neuston nets at night. In open ocean regions it occurs spasmodically in the tropics, but it a numerically dominant species in the Northwest African upwelling region. The distribution map shows that it is a species associated with other upwelling centres such as the Benguela system (Iles 1953), the Humboldt Current (Martens 1979) and the Somali Current Region. A closely related species A. minor has been reported from the fjords along the Vancouver coastline (McHardy 1964) and may also occur in the California Current, but regrettably there have been no studies of the halocyprids in the region. The reports of this species in the Indonesian Seas may be the result of confusion with elsae Poulsen 1973, which has rounded shoulder vaults. But this species described by Poulsen (1973) is known only from a single juvenile specimen.
| SOND | n | Mean mm | s.d. | Range mm |
|---|---|---|---|---|
| Female | 111 | 2.25 | 0.091 | 2.03-2.43 |
| Male | 42 | 2.01 | 0.061 | 1.88-2.13 |
| vi | 50 | 1.51 | 0.059 | 1.38-1.63 |
| v | 6 | 1.02 | 0.030 | 0.98-1.08 |
| iv |
| South Atlantic | n | Mean mm | s.d | Range mm |
|---|---|---|---|---|
| Female | 204 | 2.28 | 0.092 | 2.12-2.44 |
| Male | 116 | 2.03 | 0.047 | 1.90-2.12 |
| vi | 130 | 1.55 | 0.054 | 1.44-1.64 |
| v | 130 | 1.05 | 0.032 | 1.00-1.16 |
| iv | 18 | 0.74 | 0.026 | 0.70-0.80 |
