- Arms
- Arms < half ML; arms II=III>I=II.
- Arm suckers biserially arranged and relatively small (largest suckers midarm); except for hectocotylus, each arm usually with 75-78 suckers (range 66-87).
- Arm suckers with 5,7 or 9 teeth on distal 2/3 of sucker rings, depending on sucker size; central tooth generally slightly larger than lateral teeth.
- Tentacles
- Proximal region of club with suckers in two series with each sucker attached to base of trabecula as on arms, no locking apparatus is present; middle (manus) region suckers in tetraserial arrangement with small lateral suckers attached to trabeculae and large medial suckers attached directly to club; carpal area suckers similar in dentition to arms suckers.
- Manus area of club with suckers in four series; large, medial club suckers with 15 relatively large, sharp teeth alternating with 15 smaller blunt teeth around entire ring; distal teeth, especially blunt ones, distinctly larger; distal medial tooth larger than others but degree of enlargement variable.
- Dactylus area of club with suckers in four series; trabeculae reduced, low protective membrane better developed on ventral margin; sucker dentition similar to that of manus-area suckers.
- Club generally with about 155 suckers total. photo
- Proximal region of club with suckers in two series with each sucker attached to base of trabecula as on arms, no locking apparatus is present; middle (manus) region suckers in tetraserial arrangement with small lateral suckers attached to trabeculae and large medial suckers attached directly to club; carpal area suckers similar in dentition to arms suckers.
- Head
- Beaks
- Lower beak with shoulder tooth, transparent strip along jaw-edge extension, low wing fold, broad hood with notch, rostral edge about equal to hood length; lateral wall without fold, rostrum with pronounced hook. Color blacker than general in ommastrephids.
- Calculated regression (r2 = 0.756; n = 67) of lower rostral length (r) in mm against wet weight in grams (w):
ln w = 2.405 = 2.012 ln r
- Calculated regression (r2 = 0.736; n = 67) of lower rostral length (r) in mm against mantle length in mm (l):
l = 102.0 + 29.47 r
- Lower beak with shoulder tooth, transparent strip along jaw-edge extension, low wing fold, broad hood with notch, rostral edge about equal to hood length; lateral wall without fold, rostrum with pronounced hook. Color blacker than general in ommastrephids.
- Foveola, in funnel groove, with 7 longitudinal folds; side pockets absent.
- Statoliths
- Beaks
- Funnel
- Funnel organ
Click on an image to view larger version & data in a new window
Figure. Ventral view of the funnel cut open of M. hyadesi showing the shape of the funnel organ. Drawing from Rodhouse and Yeatman (1990).
- Funnel/mantle locking apparatus typical for family but with mantle component showing similarity to that of Todarodes pacificus in cartilage at the anterior tip (see Comparisons of the funnel-locking appartus).
- Funnel organ
- Fins
- Fin length about 40% of ML.
- Posterior fin angle 47-55°.
- Photophores
- Photophores absent.
- Photophores absent.
- Pigmentation
- In live specimens: Dorsal surface of mantle with very dark purple coloration; lateral mantle red/brown; ventral mantle silver/white.
- In live specimens: Dorsal surface of mantle with very dark purple coloration; lateral mantle red/brown; ventral mantle silver/white.
- Gladius
- Gladius with typical ommastrephid shape, reinforced with one central and two lateral ribs; vane 20% of total length.
- Gladius with typical ommastrephid shape, reinforced with one central and two lateral ribs; vane 20% of total length.
- Viscera
- Spermatophore
- Spermatophore
- Measurements and counts
Character Range mean +/-sd Range mean +/-sd Type specimen Males Females Mantle width index 19.0-29.7 23.4 2.1 19.9-26.8 22.8 1.6 19.0 Head length index 12.9-17.4 15.8 1.0 12.6-17.6 15.7 1.0 19.0 Head width index 12.0-18.4 15.5 1.4 13.2-17.7 15.5 1.2 Fin length index 38.2-45.6 41.6 1.9 38.4-45.5 42.0 1.8 43.0 Fin width index 54.3-66.5 60.0 2.8 55.5-64.3 59.4 2.3 55.5 Arm I length index 29.5-43.8 37.8 3.3 29.9-43.2 36.9 2.8 37.0 Arm II length index 34.6-48.8 41.5 3.0 35.2-45.7 40.4 2.7 41.0 Arm III length index 35.5-49.2 42.0 3.2 35.7-46.1 40.9 2.6 43.0 Arm IV length index 27.7-36.5 32.5 2.3 30.1-40.8 35.2 2.6 37.0 Hecto length index 6.6-14.9 10.5 2.3 Tentacle length index 49.3-66.9 58.6 4.7 44.9-70.2 59.8 5.2 Club length index 38.2-55.6 48.4 4.1 37.3-57.0 48.6 4.2 50.0 Gladius length index 91.9-100.0 95.1 1.6 91.9-89.9 95.5 1.6 Gladius width index 2.8-4.7 3.3 0.4 2.6-3.7 3.1 0.2 Rhachis length index 74.5-85.5 78.5 2.6 72.6-81.7 77.4 2.0 Rhachis width index 3.8-4.7 4.3 0.2 3.9-5.0 4.3 0.3
Comments
The above characteristics are from Rodhouse and Yeatman (1990).