Luminous Fire Squid

Pyroteuthis addolux

DESCRIPTION.—The mantle is conical and tapers rapidly to a posterior point. The tip of the mantle consists of little more than an integumentary layer which covers the pointed conus of the pen. The mantle wall, for most of its length, is thick and muscular. The free margin projects in the area of the ventral locking-cartilages and in the nuchal region.

The fins are separate and each is nearly circular in outline, having broad, free anterior and posterior lobes. The fin length is about 40–50% of the mantle length, and the combined fin width is about 70–80% of the mantle length.

The funnel is short; it reaches anteriorly to approximately the level of the midpoint of the lenses. The funnel locking-cartilage has a straight groove. The dorsal pad of the funnel organ has in inverted V-shaped pad which bears median ridges on each of the lateral arms and a very small anterior papilla. The ventral pads are oval and extremely large. A funnel-valve is present.

The head is large; its width is greater than that of the mantle. The large eyes occupy the entire lateral sides of the head. A distinct anterior sinus on the eyelid is lacking. A thick “olfactory” papilla is present on either side of the head at the posterior end just lateral to the funnel; the papilla curves forward in an anteromedial direction. A nuchal crest and nuchal folds are lacking. The nuchal cartilage is oval and bears a median ridge with a central groove.

The arms are robust; they are about 50–60% of the mantle in length and in the order of 4=3=2>l. Large trabeculate protective membranes are present on the ventral borders of arms I–III, but are greatly reduced on the dorsal borders. Arms IV have low membranes on their dorsal borders, but none on their ventral borders. Arms I–III all have well-developed aboral keels; arms IV have large, lateral keels. The armature is biserial throughout and consists of hooks over most of the arm length, although there are suckers basally and distally. The hooks of arms IV are considerably smaller than those of the other arms. The hooks have no trace of an aperature and a small secondary cusp is present beneath the major one. This secondary cusp is greatly elaborated in the proximal hooks of the hectocotylus. There appears to be considerable sexual dimorphism in the armature; however, since only a single male was examined, this will need confirmation. The male lacks distal suckers on arms II and III, while females have approximately 4–9 suckers. The male also has a slightly greater number of hooks (21–23 hooks) on arms II and III than do females (14–17) and a lesser number of proximal suckers. The structure of the suckers appears to be similar on all arms except the dorsal pair. The first 2–6 suckers in the distal series of arms I are typical, but the following suckers have lost the outer chitinous ring and are more globular. The first few of these latter suckers are slightly enlarged over the adjacent typical suckers. The globular suckers have smooth rings. The proximal suckers from arms IV have approximately 10 teeth around the margin of the inner chitinous ring. The teeth of the distal margin are rounded and separate from one another, while those of the proximal margin are truncate and closely adjacent, almost fused to one another.

The right arm IV of the male is hectocotylized by the presence of a short semicircular membrane on the ventral border of the arm about one-third of the arm length from the tip of the arm. The 2 rows of hooks proximal to the membrane are more widely separated than in the other arms.

The tentacles are moderately long and bear short, unexpanded clubs. The club, on its proximal two-thirds, is bounded by very low, trabeculate, protective membranes. The manus has a single row of 3–5 hooks dorsal to which is a slightly irregular row of relatively large suckers, and ventral to it is a row of small suckers. The remainder of the club distally bears 4 rows of suckers that gradually diminish in size. There is a distinct carpal cluster mat consists of 3 suckers and an equal number of pads. The largest suckers of the club each have about 13 broadly separated, blunt teeth around the entire margin of the inner chitinous ring, with those of the proximal margin distinctly larger than those of the distal margin.

There are no photophores present on the surface of the mantle; however, a number of light organs are situated on the visceral sac. A large photophore is located on either side of the anus. A transverse series of 3 photophores is located on the midline between the gills; the median member is much the largest. A large round photophore is located at the base of each gill. Posterior to the median, ventral mantle artery lies a single round photophore that is followed farther posteriorly by another median photophore. The latter 2 photophores are often bilobed. There is a final median, round photophore located near the tip of the body at approximately the level of the most posterior edge of the fin.

Twelve photophores are present on the bulbus of the eye: 3 are situated on the anterior margin near the bases of arms II and III, another is immediately posterior to the lens. On the anteroventral margin of the bulbus, mere is a series of 5 large photophores that are somewhat staggered in position. The second photophore from the posterior end of the series is the largest. Anteriorly and medially from this photophore is an additional series of 3 very small light-organs.

A series of 7 photophores is imbedded in the tentacular stalk. Near the base of the tentacle, the stalk is bent sharply. This bend is easy to locate and is a permanent feature of all members of the subfamily. At the distal end of this area is a round photophore that is deeply buried in the stalk. Shortly distal to this is a smaller round photophore that lies more superficially near the aboral surface of the stalk. Near the proximal end of the carpal cluster is another round photophore located near the aboral surface of the stalk. Approximately evenly spaced between these proximal and distal photophores are 4 elongate light organs near the aboral surface of the stalk.

The dorsal surface of the mantle, head, and arms is covered with large, reddish brown chromatophores; smaller chromatophores of the same color are present on the ventral surfaces. Most chromatophores overlie a silvery, iridescent layer.

The buccal connectives attach to the dorsal borders of arm IV.

The eggs of the gravid females measure 1.0 mm in in diameter. The spermatophores’ of the male are short, compact, and lack coils in the ejaculatory apparatus.

TYPE LOCALITY.—31°39′ N, 133°16′ W, eastern North Pacific Ocean.

LOCATION OF TYPE.—University of Southern California, U.S.C. Hancock collections, AHF Cephalopod Type No. 2.

Pyroteuthis addolux Young, 1972

ORIGINAL REFERENCE.—Pyroteuthis addolux Young, 1972:22, pls. 3B, 4I–Q,S.

DEPOSITION OF TYPES.—Holotype: SBMNH 34962, female, 45 mm ML, R/V Swan sta 27A, Northeast Pacific, 31°39′N, 133°16′W, 1966, good condition.

Paratypes: SBMNH 34963, male, 30 mm ML, R/V Swan sta 13A, Northeast Pacific, 26°N, 147°W, 1966, good condition. SBMNH 34964, female, 20 mm ML, R/V Velero IV sta 8238, off Santa Catalina Island, California, 33°28′N, 118°48′W, good condition. SBMNH 34965, female, 23 mm ML, R/V Velero IV sta 10838, off Baja California, 31°14′N, 118°45′W, good condition.

GEOGRAPHICAL DISTRIBUTION.—Eastern North Pacific; off Hawaiian Islands (Young, 1978).

Pyroteuthis addolux is a species of squid in the family Pyroteuthidae. It is distinguished from other members of the genus Pyroteuthis by the shape of photophores on the tentacles and the shape of the hectocotylus. The hectocotylus is located on arm IV, containing 10 proximity hooks, and six to 15 suckers at the tip. P. addolux ranges from south of the Hawaiian Islands, to the subantarctic boundary. They exhibit minor geographical variance, as southern specimens are slightly smaller than their northern counterparts. P. addolux is the only member of the genus to occur in the North Pacific, but additional members of the family Pyroteuthidae have also been found. The species has been observed using bioluminescence to reduce its silhouette in dim surrounding light. The type specimen was taken off southern California and described in 1972 by Richard E. Young.

Pyroteuthis addolux apparentlyt undergoes a diel vertical migration in which spends th day at depths of 450-500 mbefore ascending to 150-200m at night to feed, most likely on copepods and other small crustaceans. The larger individuals do not appear to migrate each night. The oocytes contained in the ovary of a sexually mature female had a length of 1.0mm, when they hatch they produce planktonic paralarva. The males have short spermatophores.

mesopelagic