Banded Piglet Squid

Helicocranchia pfefferi Massy, 1907

Helicocranchia pfefferi Massy, 1907, p.382; 1909, p.34, pl.3, figs. 1–3.—Robson, 1948, p.130.

Teuthowenia (Helicocranchia) pfefferi.—Pfeffer, 1912, p.740.—Grimpe, 1922, p.98.—Massy, 1928, p.36.

Desmoteuthis megalops [parts], Muus, 1956, p.9; 1962 p.9.

Megalocranchia (Helicocranchia) pfefferi.—Voss, 1960, p.433.

DESCRIPTION.—The mantle is broadest in the midportion; posteriorly, it tapers to a blunt point. The mantle wall is thin but muscular and often has a leathery texture. It is fused to the head in the nuchal region and to the lateral edges of the funnel; no cartilaginous tubercules or pads are present at these points.

The fins are separate, paddlelike in shape, and have large posterior lobes. Except at the extreme anterior ends, the fins are supported exclusively by the pen which projects dorsally above the mantle. The small posterior tip of the mantle, therefore, not only extends beneath fins without being attached to them, but also lacks the supporting tip of the pen.

The funnel is extremely large; it extends well past the bases of the arms and is very broad. The dorsal pad of the funnel organ has roughly the shape of an inverted V. A slender papilla arises from the mid-anterior portion of each lateral arm and also from the midportion of the apical region. Each ventral pad has an L-shaped appearance with the transverse limb shorter and much broader than the longitudinal one. A funnel valve is not present, and the funnel is free from the head laterally.

The head is short and narrow. The eyes, small relative to the size of the body, project from the head and point forward at roughly a 45° angle to the body axis. Each eye has a well-formed ventral rostrum with an ill-defined photophore on its proximal face. A small “olfactory” papilla arises from the tissue covering the lateral surface of each eye.

The arms are very small and slender. The arm formula is III>II>I=IV. All arms have low, protective membranes without apparent trabeculae on both the dorsal and ventral margins. Narrow aboral keels are present on arms I–III, and lateral keels are present on arms IV. All arms have biserial suckers over their entire lengths except for arms I and II of males. Each inner chitinous ring has about 7–10 low, rounded, or sometimes pointed teeth on the distal margin; the proximal margin is smooth. These teeth are very difficult to see under the microscope.

In males, approximately the distal one-fourth to one-third of arms I and II are modified. On each arm I, the size of the suckers and the diameter of the arms decrease abruptly and the number of sucker rows increases to about 4. On each arm II, the tips are similarly modified except that the number of rows increases to 8–9. These suckers have inner rings that are disproportionally small and apparently lack teeth.

The tentacles are long and moderately robust. The tentacular clubs are small but expanded and bear suckers in 4 series. At the proximal end of the manus, the suckers of the median rows are slightly enlarged over those of the marginal rows. On the dactylus, the suckers in a transverse series grade in size from the largest in the ventral row to the smallest in the dorsal row. At the tip of the dactylus, a small lobe bearing 3–4 tiny suckers is present. On the manus, the inner chitinous rings of the suckers have about 8–10 slender, pointed teeth on the distal half of the margin. Laterally, the teeth diminish rapidly in size and form only small pointed knobs proximally. The proximal 2 suckers in the dorsal row of the manus are distinctly reduced in size. A broad, trabeculate protective membrane is present along the entire ventral margin of the club, but the dorsal membrane terminates along the base of the dactylus. A short dorsoaboral keel is present on the dactylus. About 13–17 pairs of small suckers alternating with knobs extend along almost the full length of the tentacular stalk. Buccal connectives attach to the ventral borders of arms IV.

H. pfefferi has a characteristic color pattern. The mid-dorsal surface of the mantle has scattered elongate chromatophores. A strip of chromatophores extends along each dorsolateral side of the anterior two-thirds of the mantle. The lateral sides have a series of short, transverse bars, while the ventral surface has scattered chromatophores with a small concentration in the anterior midline.

TYPE LOCALITY.—Near Ireland, 51°54′ N; 11°57′ W.

LOCATION OF TYPE.—British Museum (Natural History).

Helicocranchia pfefferi, the banded piglet squid, is a small squid of the genus Helicocranchia. Adults of this species are mesopelaegic.

circum global

circum-(sub)tropical

mesopelagic

Known from seamounts and knolls