LOWER BEAK
We examined five beaks of Mt. pyrodes from individuals (53, 65, 102, 145, 155 mm ML). The following characters are taken from Clarke (1986). Arithmetic means, based on three squid (65, 102, 145), are used for characters requiring measurements.
- Pigmentation - Normal.
- Pigmentation pattern - See photographs.
- (Wing length)/(visible rostral edge) (profile) - 1.93
- Height/baseline (profile) - 1.07
- (Length from rostral tip to wing tip projected on baseline)/baseline (profile) - 0.24
- (Hood length)/(crest length) (profile) - 0.60
- (Crest length)/baseline (profile) - 0.62
- (Rostral base)/(visible rostral edge) (profile) - 1.02
- (Hood length)/(visible rostral edge) (profile) - 0.86 (n=2)
- Rostral width ratio [LRL/(length between jaw angles)] - 2.09
- Wing angle (= visible jaw angle in profile) - Obtuse.
- Shape of rostral edge - Gentle curve.
- Rostrum (profile) - Wthout unusually slender taper.
- Hood distance from crest - Normal to close.
- Crest - Often slightly curved.
- Lateral wall notch - Normal.
- Hood-wing - Broad.
- Hood notch - Shallow.
- Lateral walls to free corner - Well separated with increasing but low divergence from one another.
- Hood midline - Moderately curved.
- Hood surface without prominent longitudinal ridges or grooves.
- Wing fold - Low, rounded, without distinct groove between wing fold and shoulder blade at 102 mm ML but with prominent fold and groove in adult. Wing fold obscures jaw angle in profile.
- Shoulder blade - Shoulder blades narrow (much deeper than wide) trapezoidal in shape. Distal end of the shoulder blade tends to project above the shoulder more than the proximal end.
- Shoulder cartilage - Shoulder cartilage prominant at 102 mm ML, absent in mature females.
- Jaw angle - Approximate right angle.
- Jaw edge extension without step and with prominent angle point extending well past shoulder padding.
- Jaw edge in cross-section - Blunt
- Crest in cross-section - Rather broad.
- Lateral wall - Lateral-wall fold with a solid ridge that that slightly overhangs its base anteriorly; lateral wall fold with sharp medial groove and short, steep-sloping sides.
Figure. Left and right side views of the same lower beak of Mt. pyrodes, 145 mm ML, 5.5 mm LRL, mature (spent) female, northern Hawaiian waters. Photographs by R. Young.
Figure. Figure. Left and right side views of the same lower beak of Mt. pyrodes, 102 mm ML, 3.4 mm LRL, immature female, Northeast Pacific, 29°N, 118°W. Photographs by R. Young.
Figure. Left and right side-oblique views of the same lower beak of Mt. pyrodes, 145 mm ML, mature (spent) female, northern Hawaiian waters. Photographs by R. Young.
Figure. Front (left) and rear (right) views of the same lower beak of Mt. pyrodes, 145 mm ML, mature (spent) female, northern Hawaiian waters. Photographs by R. Young.
Figure. Figure. Two posterior-oblique views of the same lower beak of Mt. pyrodes, 145 mm ML, mature (spent) female, northern Hawaiian waters, showing the width of the lateral wall ridge (arrows). Photographs by R. Young.
Figure. Left - Top view of the lower beak of Mt. pyrodes, 145 mm ML, mature (spent) female, northern Hawaiian waters. Right - Side view of the lower beak of Mt. pyrodes, 155 mm ML, 4.6 mm LRL, mature (spent) female, northern Hawaiian waters, that has been cut in half and laid flat with drawn cross-sections of the lateral wall overlayed where the cuts occurred. Photographs by R. Young.
Comments
The lower beak of Mt. pyrodes is somewhat intermediate in features between the other members of the tall-, slender-beak species (Echinoteuthis atlantica/E. famelica and Mastigopsis hjorti). It is most easily distinguished in young beaks by the shape and size of the shoulder blade and the somewhat broader crest. It differs, among other features, from E. atlantica/E. famelica in the lack of a lateral-wall ridge in the form of a fin and from Mastigopsis hjorti in the larger lateral wall ridge which more distinctly overhangs its base.
UPPER BEAK
Figure. Side views of the upper beaks of Mt. pyrodes. Left - 145 mm ML, mature (spent) female, northern Hawaiian waters. Right - 102 mm ML, immature female, Northeast Pacific, 29°N, 118°W. Photographs by R. Young.
Figure. Various views of the upper beak of Mt. pyrodes, 145 mm ML, mature (spent) female, northern Hawaiian waters. Left - Top view. Middle - Bottom view. Right - Front view.Photographs by R. Young.
Comments
To be added.
