Promachoteuthis sp. A

Introduction

Promachoteuthis sp. A is known from two specimens: the smaller holotype, an immature female 58 mm ML and a paratype, an immature female, 102 mm ML. The paratype was captured by the R/V WALTER HERWIG in 1973 while the holotype was captured by the R/V G.O. SARS in 2004 and was in near-perfect condition. Both were taken from the North Atlantic in nets that fished to depths greater than 2,000 m. Virtually nothing is known of their biology.

Diagnosis

A Promachoteuthis ...

• without nuchal fusion between head and mantle.
• with mostly 3-4 series of suckers on arms.
• with papillae on tentacles.

Characteristics

1. Arms
1. Arms with three or four rather irregular suckers series in mid-region sometimes appearing as up to six series.
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Figure. Oral view of the midregion of a lateral arm of Promachoteuthis sp. A, holotype, preserved.

2. Tentacles
1. Tentacles thick at base (slightly thicker than adjacent arms); club not flattened; club) about 60% of tentacle length.
2. Each tentacle with two series of long papillae near oral midline at tentacle base but diverging to be lateral to club; papillae often with stubby branches in holotype but become flattened, highly branching or merge into a complex membrane in the paratype.
3. Darkly pigmented ridges present along the lateral margins of the aboral surface of each tentacle; distally the ridge breaks into small papillae. Pigmented ridges in paratype less prominent and restricted to middle third of tentacle.
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Figure. Lateral views of the tentacles of Promachoteuthis sp. A, holotype, preserved. Note the long papillae that extend from the proximal regions of the tentacles. Arrows point to pigmented ridges. Photograph by R. Young

3. Head
1. Head extremely small with very small eyes buldging laterally from reduced head.
2. Eyelid forming a small, circular opening.
3. Eyelid over lens opaque but with, apparently, a somewhat clearer central region.
image infoimage info

Figure. Side views of the head of Promachoteuthis sp. A, holotype. Left - Preserved squid. Left arrow points to edge of iris; right arrow points to slit which is the collapsed opening of the eyelid. Right - Unpreserved squid. Eyelid opening a small, dark oval pore; iris visible but difficult to discern; whitish, oval ring that passes by the eyeopening appears to define a slightly less opaque (i.e. clearer) region of the eyelid but it is difficult to distinguish in the photograph on the left. Photographs by R. Young.

4. Mantle
1. Anterior mantle-margin free from the head. A nuchal cartilage is present.
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Figure. Anterior dorsolateral view of the mantle opening of Promachoteuthis sp. A, holotype, preserved. Arrow points to nuchal cartilage. Photograph by R. Young.

5. Fins

1. Fins large; large anterior lobes present; posterior lobes absent in holotype but small, distinct posterior lobes present in paratype.

Comments

More information on the description can be found here.

Promachoteuthis sp. A is very distinctive and easily separated from other members of the genus by the peculiar tentacles among many other features.

Distribution

Type locality - Central North Atlantic at 53°05’N, 36°46’W (R/V G.O.SARS MARECO cruise super station 14, local station 341)in an trawl that fished to a maximum depth of 2792 m in 2004. Paratype came from the Eastern North Atlantic at 46°00'N, 15°49'W (R/V WALTER HERWIG station 714) in a trawl that fished to 2650 m.

References

Toll, R. B. 1998. The gladius is teuthoid systematics. Smithson. Contr. Zool., No. 586: 55-68.