Species of Abralia are small squid some of which are associated with shallow bottoms on steep slopes and as such are members of the mesopelagic-boundary fauna.

Brief diagnosis:

An enoploteuthid ...

• without large, black photophores at the tips of arms IV (see, however, A. astrolineata).
• with fins extending to posterior tip of tail.

1. Arms
   1. Arm suckers present distally on Arms IV.
      
      
2. Tentacles
   1. Manus of club with one series of hooks; two series of suckers.
      
      
3. Buccal crown
   1. Typical chromatophores on oral surfaces of buccal crown.
      
      
4. Photophores
   1. Enlarged photophores on tips of arms IV generally absent; if present, not covered by black chromatophores (exception in A. astrolineata).
   2. Five to twelve photophores on each eye.
   3. Complex photophores of integument without red-colored filters.

Comments

In life, the integumental photophores have a characteristic appearance. The photo shows the three types of integumental photophores. A "lensed" photophore (white arrow) has a blue color and white ring. A "simple" photophore (black arraow) is small and violet-colored. The remaining are "complex" photophores and have a central green color and small "satellite" green-color points. Often complex photophores will appear blue rather than green depending on their physiological state (see Young and Arnold, 1982). The black dots are chromatophores.

The structure of a complex photophore can be seen here.

Classification

Species of Abralia are generally placed into six subgenera but these may not all be natural groups. The following table (modified from Tsuchiya and Okutani, 1988) shows the primary taxonomic features of each group.

	Abralia (Abralia)	Abralia (Asteroteuthis)	Abalia (Astrabralia)	Abralia (Pygmabralia)	Abralia (Heterabralia)	Abralia (Enigmoteuthis)
No. distal sucker series on arms I-III	3-4	3-4	2	2	2	2
Which arm IV hectocotylized	Right	Left	Right	Right	Left	Right
No. Club hooks	>4	<5	>4	<4 (often 1 or 2)	<5	>5
No. of types of ocular photophores*	2	2	1	1	2	1
Large, unpigmented caudal and arm IV-tip photophores	No	No	Yes	No	No	No
Attachment of buccal connective to arm III	Ventral	Ventral	Ventral	Ventral	Ventral	Dorsal

*Refers to reflective properties (e.g., orange, silvery, opaque) that indicate structural differences other than size.

Depth range based on 426 specimens in 21 taxa.
Water temperature and chemistry ranges based on 330 samples.

Environmental ranges
  Depth range (m): 11 - 2587
  Temperature range (°C): 3.021 - 27.572
  Nitrate (umol/L): 0.006 - 40.784
  Salinity (PPS): 34.151 - 37.543
  Oxygen (ml/l): 0.678 - 6.275
  Phosphate (umol/l): 0.034 - 2.956
  Silicate (umol/l): 0.774 - 73.601

Graphical representation

Depth range (m): 11 - 2587

Temperature range (°C): 3.021 - 27.572

Nitrate (umol/L): 0.006 - 40.784

Salinity (PPS): 34.151 - 37.543

Oxygen (ml/l): 0.678 - 6.275

Phosphate (umol/l): 0.034 - 2.956

Silicate (umol/l): 0.774 - 73.601
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Barcode of Life Data Systems (BOLD) Stats
                                        

Specimen Records:	4	Public Records:	2
Specimens with Sequences:	4	Public Species:	2
Specimens with Barcodes:	4	Public BINs:	1
Species:	3
Species With Barcodes:	3

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