Stigmatoteuthis dofleini Pfeffer 1912

Histioteuthis dofleini (Pfeffer, 1912)

Calliteuthis ocellata.—Chun, 1910, p.147; pl.I, figs.1, 2; text fig.23a, b.

Stigmatoteuthis Dofleini Pfeffer, 1912, p.288.

Stigmatoteuthis dofleini.—Sasaki, 1929, p.258; text fig.126—127; pl.22, figs.1–3.

Histioteuthis dofleini.—Voss, 1967, p.74; 1969, p.784.

DESCRIPTION.—The mantle is thick walled and moderately muscular. It is conical, but tapers to a blunt point. The free margin projects at the locking-cartilages. Beneath the thin outer integument, the mantle is covered with short, broad, wartlike papillae.

The fins are short (about one-third of the mantle in length and one-half of the mantle in width). Each fin is nearly semicircular in outline and has small, free anterior and posterior lobes. The papillate tissue of the mantle extends onto the medial portion of the dorsal surface of the fins.

The funnel is short, and free from the head laterally. The dorsal pad of the funnel organ has an inverted V-shape with an inverted V-shaped central ridge terminating in a small anterior papilla. The ventral pads are oval. The funnel locking-cartilage has a straight but deep and broad central groove which opposes a large, slightly curved ridge on the mantle.

The head is large and broad. The left eye is nearly twice the size of the right. There appears to be 3 nuchal folds rising from the nuchal crest on either side of the head. The second fold bears the “olfactory” organ. The nuchal cartilage is long and slender; it bears a median ridge with a central groove. The head and aboral surfaces of the arms have weltlike papillae beneath the outer epidermis as on the mantle.

The arms are very long (over 175% of the M.L.); they are broad at the bases and attenuate at the tips. The arm formula is I = IV>II = III. Rather broad aboral keels are present on the distal half of arms III, but arms I and II have keels that are only slender ridges. Arms IV have thick, fleshy lateral keels. Arms I–III have large trabeculate protective membranes on both the dorsal and ventral margins; these are much less developed on arms IV. Arms I of the single large female examined have suckers arranged in 3 rows at the arm tips (this is not typical of the species according to N. Voss); otherwise, all arms have biserially arranged suckers. The suckers of arms I–III are much larger than those of arms IV. The inner chitinous rings have been destroyed by the fixative in the largest specimen; however, in the 14 mm M.L. specimen, about 7–10 triangular teeth are present on the distal half of the inner ring; laterally and proximally these diminish to small knobs. An outer web connecting all arms at their bases is relatively well developed, being approximately 20–25% of the mantle in length.

The tentacles are long and muscular. The tentacular clubs are slender but expanded, and nearly 40% of the M.L. The suckers of the manus are somewhat irregularly arranged, but can be generally divided into 5 longitudinal series. There is a row of very large suckers in the median portion of the club. Dorsal to this row is a very irregular row of medium-size suckers that alternate somewhat in size. Ventral to the central series is another, more regular row of medium-size suckers. Along both the dorsal and ventral margin is a row of very small suckers. Along the ventral margin, this row may be incomplete. The suckers of the dactylus also appear somewhat irregularly arranged. In a transverse line through the dactylus there are 3–4 suckers. At the tip of the club there is a small flap that carriers 7–9 suckers. The inner rings of the largest suckers of the manus have as many as 60 sharp teeth around the entire margin. A large dorsoaboral keel is present on the dactylus. The carpal locking-mechanism consists of a row of 2 suckers with alternating pads at the base of the manus along the dorsal border. Proximal to the manus there is a median row of 3–4 alternating suckers and knobs. A small sucker is located near the proximal member of this series. Proximal to the median row is a series of 2–3 pairs of suckers alternating with 2–3 pairs of knobs. The first set in this series is situated obliquely on the stalk, but the remaining lie along the ventral margin. This series terminates with a single sucker or knob.

The buccal connectives attach to the dorsal borders of arms I, II, and IV and to the ventral borders of arms III.

The ventral surface of the mantle is covered with large, well-separated photophores. A somewhat irregular row of smaller photophores extends along the free margin of the mantle. Dorsally the photophores in this series lie somewhat farther from the mantle margin and are very small. There are 22–23 photophores in this series. On the dorsal surface of the mantle, the photophores are small and scattered. I counted a total of 103 photophores on the entire mantle; however, since some are very difficult to locate in the present material, this number may not be exact. The photophores on the ventral surface of the mantle are arranged approximately in diagonal rows.

Photophores are arranged in diagonal rows on the ventral surafce of the head, except for a transverse series that extends along the posterior margin. Seventeen photophores, embedded in the margin of the eyelid, encircle the right eye. Photophores are not so regularly arranged around the enlarged left eye; unfortunately, their exact arrangement cannot be determined in the material available. A few scattered photophores are present on the dorsal surface of the head. In the proximal half of the ventral arms, photophores are arranged in 3 longitudinal rows. On the third quarter, or slightly more, of the arm, photophores are arranged in 2 rows, and on the distal segment only a single row is present.

Arms I–III all have a single row of large photophores, extending the full length of the arms along the ventral margin of the aboral surface. A second row, near the dorsal margin, of very small photophores is also present on all arms. It is possible that other photophores are present, but not detectable in the present material.

This animal has a uniform purplish red coloration.

The data for the largest specimen available are: Sex, ; M.L., 150 mm; M.W., 65 mm; H.W., 75 mm; F.L., 54 mm; F.W., 77 mm; arm lengths for arms I–IV respectively, 265 mm, 318 mm, 313 mm, 268 mm; Tent. L., 345 mm; Club L., 61 mm.

TYPE LOCALITY.—Sagami Bay, Japan.

LOCATION OF TYPE.—Not traced.