Abraliopsis sp. V

Introduction

Abraliopsis (Pfefferiteuthis) sp. V is one of the more distinctive species in the subgenus.  Its size is a bit smaller than other members of the subgenus, reaching lengths of 28 mm ML in males and 35 mm ML in females. Known in the Central North Pacific from the equator to Hawaii (rare in Hawaii) and also a single record near New Guinea.

Brief diagnosis:

An Abraliopsis (Pfefferiteuthis) ...

• without keels or carpal flaps on tentacular clubs.
• with largest ventral hooks of tentacular clubs about 2 times height of dorsal counterparts.
  
• with many scattered photophores in Lateral Head Sector; mostly located in anterior half of sector and at base of Central Arm IV Sector.
  

Characteristics

1. Arms
   1. Females
      1. Hooks on arms I largest and with enlarged median processes.
      2. Arms without tubercles.
         
         

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         Figure. Ventral view of arms I (the two middle arms) and II of a female Abraliopsis sp. V (33 mm ML, paratype) showing the larger size of the hooks on arms I. Insert: Side (left) and front (right) views of a large arm I hook showing the vane-like median process.
         

   2. Males
      1. Arms I without enlarged hooks and hooks without strong median process. Hooks nearly aligned in single series over much of arm.
         
      2. Arms longer in males and with more hooks.
      3. First basal sucker, arms III, ventral series much larger than second basal sucker of same series and about equal in size to counterpart in dorsal series. Basal suckers 2-4 of arms III, dorsal series much larger than counterparts of ventral series.
         
      4. Left arm IV highly modified: enlarged ventral protective membrane with 12-18 large trabeculae reaching up to 2.5 mm in length. Dorsal trabeculae and membrane much shorter; first few proximal trabeculae larger, size diminishes distally and membrane nearly absent. Hooks with varying sizes depending on arm position. Arm with numerous tubercules.
      5. Hectocotylus (right arm IV) with large ventral flap and smaller, offset dorsal flap. Hooks with varying sizes depending on arm position. Arm with numerous tubercules.
         


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Figure. Oral views of arms III and IV of Abraliopsis sp. V, mature male, 30 mm ML, central Equatorial Pacific. Note the relative size of the two basal hooks of arm III, ventral series (arrows). Photographs by R. Young.


2. Tentacles
   1. Clubs relatively short and without keels or carpal flaps.
   2. Carpus with 2-4 suckers and pads. 
   3. 2-4 large ventral hooks, 2-4 smaller dorsal hooks.
   4. Largest ventral hook of club about 2X dorsal counterpart in height.
      
      

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      Figure. Ventral (left), oral (center) and dorsal (right) views of the tentacular club of Abraliopsis sp. V, mature male, 30 mm ML, central Equatorial Pacific. Photographs by R. Young.

3. Fins
   1. Fins large, 73-79% of ML.
      
      
4. Photophores
   1. Ocular photophores: 5 ocular photophores, with end members about twice diameter of adjacent photophores.
   2. Integumental photophores: 3 series on ventral head; 6 series on ventral mantle.
      
      

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      Figure. Ventral views of the integumental photophores of Abraliopsis sp. V, mature male, 30 mm ML, tropical Pacific. Left - Photograph of the preserved squid. Right - Outline drawing from photograph with all integumental photophores represented by colored dots. Red dots - Complex photophores. Blue dots - Non-complex photophores. Images by R. Young.

      Detailed information on the integumental photophores can be found here.

5. Viscera
   1. Spermatangia receptacles - Females with single pocket (stellate pocket) for storing spermatangia located in midline between anterior end of gladius and visceral mass. Dorsal collar area lacks pigmentation and folds indicating that it is not a receptacle.
      

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       Figure. Dorsolateral view of the receptacle (stellate pocket - arrow) for spermatangia of Abraliopsis sp. V, 33 mm ML. Photograph by R. Young.
      

   2. Spermatophore:
      
      

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      Figure. Spermatophore of Abraliopsis sp. V, 30 mm ML, with enlarged insert of oral end. Photograph by R. Young
      

6. Measurements and counts:
   

   	TC 44, sta. 18	TC 44, sta. 18	TC 48, loc. B	TC 43, sta. 22	TC 46, sta. 27	TC 46, sta. 23
   Sex	Female	??	Female	Male	Male	Male
   Mantle length	33	33	32	28	30	30
   Head width index	30	33	36	36	37	37
   Fin Length index	76	64	73	79	70	73
   Fin width index	94	97	103	93	100	100
   Arm Length index (R/L): I	39/33	39/-	36/-	39/-	43/-	43/-
   II	36/36	39/-	45/-	46/-	50/-	50/-
   III	39/-	36/-	42/-	39/-	47/-	53/-
   IV	49/49	42	46/46	57/61	53/60	57/63
   No. arm hooks (R/L): I	16/-; (22)	19/-; (21)	15/-; (24)	23/-	23/-; (15)	22/-
   II	19/-; (16)	21/-; (15)	18/-; (21)	26/-	27/-; (12)	24/-
   III	18/-; (12)	18/-; (12)	18/-; (20)	26/-	24/-; (8)	24/-
   IV	23/23	22/22	22/-	31/40	26/43	25/36
   Club length index (R/L)	18/18	18/20	20/-	20/-	20/20	20/18
   Club hooks (D/V)(R:L)	3/4; 3/4	4/3; 4/3	3/3	3/3; 4/3	3/3; 4/3	4/3; 4/3
   Carpal suckers (R/L)	3/4	4/5	4/-	4/4	4/4	4/4

Comments

While the abundance of blue photophores in the Lateral head and Central Arm IV Sectors is unique among A. (Pfefferiteuthis) spp., it is similar to that found in A. (Micrabralia) spp. NC1 and NC2. Therefore the identification of females (lack the characteristic A. (Pfefferiteuthis) male arms IV) requires some care. The tentacle clubs are similar only to those of A. falco within the subgenus but they are similar to those of A. lineata within A. (Micrabralia). The most distinctive feature of females, unique to this species, is the enlargement of hooks on arms I. 

Comparisons of all species in the subgenus can be found on the Abraliopsis (Pfefferiteuthis) page.

Distribution

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Figure. White dots show general regions where Abraliopsis sp. V has been collected. Background map from Google Earth.app.