Abraliopsis sp. P

Introduction

Abraliopsis sp. P is found in the tropical Pacific. It is a fairly large species for an Abraliopsis, with males reaching at least 31 mm ML and females at least 40 mm ML. It is very similar to the sympatric Abraliopsis sp. A except, primarily, for the structure of the tentacular club.

Brief diagnosis:

An Abraliopsis (Pfefferiteuthis)  ...

• with carpal flap and large keel on club.
• without photophores in central Median Mantle Sector or Medial Head Sector.
  

Characteristics

1. Arms
   1. Arms with two series of hooks and arms I-III with two series of small suckers at tip; suckers more numerous on arms I and least numerous on arms III.
      
   2. Arms IV longer in males than females.
   3. Males with right arm IV hectocotylized and left arm IV highly modified.
      
      1. Ventral flap of hectocotylus extends from 5th pair of hooks to base of enlarged arm-tip photophores. Ventral flap bilobed with proximal lobe about twice as high as distal lobe.
      2. Dorsal flap of hectocotylus extends from most distal hook, becomes abruptly reduced in height, continues distally as low ridge.
      3. Trabeculae of hectocotylus present on both margins opposite hooks; membrane between trabeculae low or absent in more proximal and distal trabeculae.
      4. Left arm IV with enlarged ventral protective membrane extending from 2nd pair of hooks nearly to tip of arm. Up to 24 large trabeculae present, up to 2.5 mm long. trabeculae slender, elongate, connected by thin, heavily pigmented membrane. Dorsal protective membrane with short trabeculae and low membrane.
         
      5. Bases of arms IV and trabeculae with numerous conical tubercules.
      6. Left arm IV with longer and more numerous hooks than right arm IV; hooks on both arms differ remarkably in size and arrangement; in some areas dorsal hooks opposite smaller ventral hooks and vice versa.
         
      

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      Figure. Oral views of arms IV of Abraliopsis sp. P, paratype, mature male, 28 mm ML, central Equatorial Pacific. Photograph by R. Young.

   4. Arms I-III with protective membranes on ventral margins, largest on arms III. Dorsal margins with short, stubby trabeculae without membranes except at distal ends of arms.
   5. Arms III in males with first 1-4 proximal hook of dorsal series much larger than their ventral counterparts. First proximal hook of ventral series equal to or smaller than subsequent hook of same series.
      
   6. Arms IV in females with stubby trabeculae on both margins and absent distally.
      
   

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   Figure. Oral views of arms of Abraliopsis sp. P, paratype, mature male, 28 mm ML, central Equatorial Pacific. Relative sizes of arms not maintained. Note that the basal sucker of arm III (male only), ventral series (arrow) is smaller, not larger, then the next sucker in the series, an important difference with Abraliopsis sp. A. Photographs by R. Young.

2. Tentacles
   1. Club keel slightly narrower than width of dactylus; extends from proximal end of base of most distal hook of dorsal series to terminal pad.
   2. Carpal flap extends from opposite carpal area to first ventral hook.
   3. Carpal pad with 4-5 (rarely 6) suckers and pads.
   4. Manus with up to 4 pairs of hooks; largest ventral hook over 3 x height of dorsal counterpart.
   5. Dactylus with 10-11 diagonal rows in four series. Sucker rings smooth, with wide aperatures.
      
      

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      Figure. Oral view of the tentacular club of Abraliopsis sp. P., paratype, mature male, 28 mm ML, central Equatorial Pacific. Note the shape of the largest hook. Photograph by R. Young.

3. Photophores
   1. Ocular photophores: Five ocular photophores; end members about 2x diameter of central photophore; middle three photophores very nearly the same size.
      
   2. Integumental photophores: 3 series on ventral head, 6 on ventral mantle.
      

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      Figure. Ventral view of Abraliopsis sp. P, mature male, 26 mm ML, central equatorial Pacific. Left - Photograph of the preserved squid. Right - Outline drawing from the photograph with all integumental photophores represented by colored dots.  Red dots - Comples photophores. Blue dots - Non-complex photophores. Images by R. Young.

      Detailed information on the integumental photophores can be found here.

4. Viscera
   1. Spermatangia receptacles: Three receptacles present; two dorsal-collar pockets and one stellate pocket.
      
   2. Spermatophore:
      
      

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      Figure. View of the spermatophore (7 mm long) of Abraliopsis sp. P with enlarged insert of oral end, mature male, 28 mm ML, central Equatorial Pacific. Photograph by R. Young

5. Measurements and counts:

   	CHG 89, sta 29	TC 44, sta. 18	TC 44, sta. 56	TC 44, sta. 56	CHG 89, sta 15	HMS 47, sta. 51
   Sex	Male	Female (mated)	Female (mated)	Male (mature)	Male (mature)	Male
   Mantle length	31	34	40	25	28	28
   Head width index	36	32	28	36	43	29
   Fin Length index	71	71	75	-	75	71
   Fin width index	90	94	90	-	93	104
   Arm Length index (R/L): I	48/-	-/47	45/-	44/-	46/-	54 /-
   II	55/-	53/-	48/-	56/-	54/-	68/-
   III	48/-	53/-	50/-	52/-	50/-	61/-
   IV	55/68	56/62	58/63	56/64	61/68	71/93
   No. arm hooks, R/L; (suckers): I	20/-; (22)	17/-; -	18/-; (22)	18/-; (24)	20/-; -	19/-; -
   II	26/-; (12)	20/-; (7)	21/-; (12)	21/-; (14)	24/-; -	21/-; -
   III	24/-; (10)	20/-; (6)	21/-; (10)	20/-; (19)	22/-; -	26/-; -
   IV	31/34	24/25	26/29	27/27	31/36	36/43
   Club length index (R/L)	19	24/24	23/-	24/-	21/-	25/-
   Club hooks (D/V)(R:L)	4/2/-	3/4; 3/4	4/4	2/4; -	3/3	-
   Carpal suckers (R/L)	5/-	4/4	5/-	5/-	6/-	5/-

Comments

More details of the description can be seen here.

Abraliopsis sp. P is very close to Abraliopsis sp. A, Abraliopsis falco and Abraliopsis atlantica. However, A. sp. P and A. sp. A have broadly overlapping distributions. They are separated primarily by features of the tentacular club: A. sp. P with large keel and carpal flap; species with A small keel (short and low) and without a carpal flap. In additionm Abraliopsis sp. P also differs from A. sp. A in lacking an enlarged basal hook on arm III, ventral series, of males. There is also a difference in the size and shape of the largest hooks on the club between these two species.

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Figure. Comparison of the club hook size and shape between Abraliopis sp. A and sp. P, side view, all with same magnification. Photographs by R. Young.

The largest hooks of A. sp. P are longer (measured from the base, around the curvature, to the tip of the claw) than those of A. sp. A and the tips of their claws are further removed from the hook shaft. Note that smaller hooks of the ventral series are very similar in the two species although the claw in A. sp. A is more strongly recurved. 

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

Distribution

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Figure. The white dots are localities where Abraliopsis sp. P has been captured. The background map is from Google earth.