Under Construction

Stoloteuthis sp. A

Richard E. Young
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Containing group: Stoloteuthis

Introduction


Figure.This was the title photograph when Stoloteuthis sp. A
was originally described as Heteroteuthis sp. A. 

When this species was first described on the Tree of Life, it was known from only a single female which had the basic shape of a species of Heteroteuthis especially with its anteriorly located ventral shield and, therefore, was descibed as an unrecognized species, Heteroteuthis sp. A. Now with several more specimens including mature males, the species clearly does not belong in Heteroteuthis. Its placement, however, is uncertain as it shows strong similarities to both Stoloteuthis and Sepiolina but is placed in the latter for reasons stated under "Phylogenetic relationships" below.

Brief diagnosis:

A Stoloteuthis with ...

The second feature is unique.

Characteristics

  1. Arms (female)
    1. Arm formula: 3>1=2=4.
    2. Tips (distal 10% of arm) without suckers on arms I, III and IV; arms II with suckers to tip.
    3. Arms I and III with keels especially broad distally. Arms II virtually without keels, arms IV with lateral membrane.
    4. Suckers of dorsal and ventral series on arms identical to one another.
    5. Web ...
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      Click on an image to view larger version & data in a new window

      Figure. Ventrolateral view of left arms I-IV of Stoloteuthis  sp. A female, 13 mm ML. Note bare arm tips on arms IV, III and I. Note the broad, distal, aboral keels  on arms I and III. Photographs by R. Young.

  2. Arms (male).
    1. Arm formula: III>I=II>IV. Arms I and IV rather blunt; arms II and III attenuate; arms I very broad broad (hectocotylized); all arms without broad distal keels.
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Oral views of the arms of Stoloteuthis sp. A, males. Left - The entire brachial crown, 16 mm ML,note the modified arms I and the stubby arms IV with modified suckers at their tips; tentacles lost during capture. Right - A larger specimen, 20 mm ML, but in poor condition, showing the modified arms I and the very long but narrow web that joins them (top arrow) and the very short web that connects to arms II (bottom arrow).

    2. Hectocotylus - Both arms I very thick, and with complex structure. Protective membranes larger on dorsal margins; secondary membranes passing from protective membrane, between suckers to midline of arm. Long, slender structures beneath surface on both lateral and medial sides of arms (apparently elongate sucker pedicles).  Suckers in 2 series at arm base but in 3 or more irregular series in mid-arm (most apparent in largest male). 
    3. Arm webs - Arms I with narrow, web between them that extends to the arm tips nearly binding them together.
    4. Suckers - Suckers of arms IV smaller than on other arms in mid-arm regions, but suckers at arm tips not greatly diminished in size; 4 terminal arm-tip suckers with opaque white tissue surrounding inner sucker rings. Arm II-IV without enlarged suckers. Most suckers globular with cup-shaped outer rings. Hectocotylus suckers globular at base but, distally, become more tubular and curved.
    5. Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Stoloteuthis sp. A, male, 16 mm ML. Left - Side view of web between arms I near arm tip (top red arrow) and much lower between arms I and II (lower red arrow). Left middle - Oral view of basal 2/3 of arms I showing curvature of some suckers. Right middle - Arm II segment at 2/3 of arm from base showing typical globular suckers. Right - Tip of arm IV showing 4 white, distal suckers.

  3. Head
    1. Small ocular pore on secondary eyelid just anterior to lens (usually difficult to locate).

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    Click on an image to view larger version & data in a new window

    Figure. Dorsolateral view of the head of Stoloteuthis sp. A, female, 12 mm ML, showing the ocular pore (arrow). Photograph by R. Young.

  4. Funnel
    1. Funnel component of the funnel/mantle locking-apparatus slightly boomerang-shaped with deep, angular pit at bend and narrow grooves on either limb. Mantle component with slender ridges extending to a high point at bend which is in posterior half of lock. Anterior edge does not reach mantle margin.
    2. Funnel connected to head by broad funnel adductor muscles that attach to funnel near distal sides of funnel lock.
    3. Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Funnel/mantle locking-apparatus of Stoloteuthis sp. A, female, 12 mm ML. Left - Side view of mantle component. Right - Frontal view of funnel component. Photographs by R. Young.

  5. Mantle
    1. Mantle margin free but nuchal cartilage fused to mantle.
    2. Ventral mantle shield confined to anterior half of mantle (see photograph under "Photophores").
    3. Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Dorsolateral view of the nuchal fushion (arrow) in Stoloteuthis sp. A, female, 12 mm ML. Photograph by R. Young.

  6. Pigmentation/iridophores
    1. Thick iridophore layer present on posteroventral surface of funnel.
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    Click on an image to view larger version & data in a new window

    Figure. Ventral view of the funnel of Stoloteuthis sp. A female, 12 mm ML, showing iridophore layer (arrow). Photograph by R. Young.

Comments

More details of the description of Stoloteuthis sp. A can be found here. 

A better understanding of the structure of the male hectocotylus along with that of other species of Stoloteuthis and of Sepiolina nipponensis is needed before the relationships of Stoloteuthis sp. can be properly determined.

Discussion of Phylogenetic Relationships

The following table shows how some of the more phylogenetically important features in ggenera compare with those characters in Stoloteuthis sp. A. This is a simplified look at the genera and is simply to indicate that placing Stoloteuthis sp. A in a known genus is not easy. We have placed most emphasis on hectocotyliation which, as defined here shows similarities between Stoloteuthis sp. A and other  Stoloteuthis spp. and Sepiolina in the special modification of arm I (although the type of modification may prove to only superficially similar). The structure of the club in the latter prevents placing Stoloteuthis there. We are basically using Stoloteuthis as a catch-all genus as it is already difficult to define with the inclusion of S. weberi.

  Hectocotylization
  club expanded
Tentacular organ
 Shield length as % of VML
Photophore pores
Mantle-head fusion
Funnel locking- apparatus
Hectocotylization symmetrical
Web sector I - long; sector II - short
1° hecto* =  arms I
Heteroteuthis
 no  yes  ~50  central no
groove
no
no
 no
Iridoteuthis
 no  yes  >80  side  yes groove or groove & pit
 yes no
no
Nectoteuthis
 no  yes  >80  ?  no groove & 2 pits
yes ?
no
 no
Amphorateuthis
 no  yes  >80  side  yes groove & pit
 yes no
no
Stoloteuthis
 no  yes  >80  central yes or no
groove
yes no
 yes
Stoloteuthis sp.A
 no  yes ~50
 central  no Groove & pit
 yes yes
 yes
Sepiolina
 yes no, insipient
 >80  central  yes groove
 yes yes
 yes
* Subjective
Title Illustrations
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Click on an image to view larger version & data in a new window
Scientific Name Stoloteuthis sp. A
Location Waters off New Caledonia
Comments Initially frozen, then thawed and photographed.
Specimen Condition Dead Specimen
Sex Female
Life Cycle Stage Mature
View Dorsolateral
Size 13 mm ML
Copyright © Jeff Dubosc
Scientific Name Stoloteuthis sp. A
Location Waters off New Caledonia
Comments Initially frozen, then thawed and photographed. Note the two arms I curved the the right in unison.
Specimen Condition Dead Specimen
Sex Male
Life Cycle Stage Mature
View Dorsolateral
Size 16 mm ML
Copyright © Jeff Dubosc
About This Page


University of Hawaii, Honolulu, HI, USA

Correspondence regarding this page should be directed to Richard E. Young at

Page: Tree of Life Stoloteuthis sp. A. Authored by Richard E. Young. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Young, Richard E. 2014. Stoloteuthis sp. A. Version 21 January 2014 (under construction). http://tolweb.org/Stoloteuthis_sp._A/149536/2014.01.21 in The Tree of Life Web Project, http://tolweb.org/

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