Vulcanoctopus hydrothermalis González & Guerra, 1998

Strugnell, Jan, Voight, Janet R., Collins, Patrick C. & Allcock, A. Louise, 2009, Molecular phylogenetic analysis of a known and a new hydrothermal vent octopod: their relationships with the genus Benthoctopus (Cephalopoda: Octopodidae), Zootaxa 2096 (1), pp. 442-459 : 450

Vulcanoctopus hydrothermalis González & Guerra, 1998

Type material examined: Vulcanoctopus hydrothermalis González & Guerra, 1998 in González, Guerra, Pascual & Briand , holotype, MNHN 2885, HOT 96 East Pacific Rise , North of Genesis , 12°48'N 103°56'W, 19 February 1996, 2647 m, male.

Additional material examined: Vulcanoctopus hydrothermalis: FMNH 307183, RV Atlantis HOV Alvin , 10°46'N 103°39'W (East Pacific Rise), Alvin Dive 3936, 17 November 2003, 2574 m, male, coll & det JR Voight. * FMNH 307184, RV Atlantis HOV Alvin , 08°38'N 104°13'W (East Pacific Rise), Alvin Dive 3926, 7 November 2003, 2541 m, male, coll & det JR Voight. FMNH 278064, RV Atlantis HOV Alvin , 9°50.333'N 104°17.482'W (East Pacific Rise), Dive 2846, 24 Oct. 1994, 2512 m, male, coll R. Lutz, det JR Voight. FMNH 287365, RV Atlantis HOV Alvin , 9°49.136'N 104°17.332'W (East Pacific Rise), Dive 3217, 17 May 1998, 2495 m, male, coll C. Fisher, det JR Voight. FMNH 287366, RV Atlantis HOV Alvin , 9°50.624'N 104°17.48'W (East Pacific Rise), Dive 3212, 13 May 1998, 2509 m, male, coll C. Fisher, det JR Voight. FMNH 307185, RV Atlantis HOV Alvin , 12°49'N 103°56'W (East Pacific Rise), Dive 3938, 19 November 2003, 2619 m, male, coll & det JR Voight. FMNH 306500, RV Atlantis HOV Alvin , 12°48.673'N 103°56.408'W (East Pacific Rise), Dive 3939, 20 November 2003, 2620 m, male, coll A. Berry & J. Voight, det JR Voight.

Diagnosis. Incirrate octopod. Biserial Suckers. Ink sac and anal flaps absent. Arms 2–4.5 times ML. Arm formula 1>2>3>4; arm length somewhat variable among 8 specimens with seemingly intact (or fully regenerated arms): arm I at least 10 mm longer than II in 5, subequal in 3; arms II at least 10 mm longer than III in 4 of 8; arms III and IV subequal in 5 of 8. Arm I with up to 166 suckers, other arms with fewer; hectocotylus carries between 58 and 83 suckers. Funnel organ W-shaped, lateral limbs shorter than medial limbs. Gills with 8 to 10 lamellae per outer demibranch. Ligula of males without strong transverse ridges LLI 8–10. Digestive gland multilobed. Maximum spermatophore length 62, maximum SpLI 125, maximum number of spermatophores 114. Mature males without enlarged suckers. Rachidian multicuspid. Integument of holotype shows evidence of some sculpture in the form of widely spaced small papillae on the dorsal and ventral mantle, but most conspicuous are the low wrinkles that cover the animal, including the oral web. These are present in both fresh and preserved specimens, not as the description stated “wrinkled in preservation” ( González et al. 1998 p. 173) .

Remarks. A female of this species was recently described ( González et al. 2008) as lacking the dark swelling described in the intestine of males ( González et al. 1998). Neither has the dark swelling been seen in 13 additional specimens, 8 from the type locality, in Field Museum collections. The condition of the optic chiasma is nearly unexplored in other deep-sea octopodids. Information on spermatophores given in diagnoses was extracted from González et al. (2002), which details variation in male specimens from the type locality. The holotype has been heavily dissected; the reproductive tract, for example, is in eight parts. Only 69 spermatophores remain in the holotype; this is similar to the next highest counts we found in 30 male specimens (70, 72, 74). The funnel organ shape is herein described for the first time based on specimens from the type locality.