Pholidoteuthis adami, sometimes referred to as the Western Atlantic scaled squid or pink scaled squid, is a deep-sea species of squid.
Description Pholidoteuthis adami is named in honor of Dr. W. Adam of Bruxelles, who named the genus Pholidoteuthis. This species was initially described as an "animal of large to gigantic size; fins a marginal fringe bordering the slender posterior point of the mantle; skin smooth; alternate cups and suckers along the entire length of the tentacular stalk". The initial description relied on 31 specimens collected by the USFWS vessel Oregon in 1950–1956; the holotype (USNM 575139) is a female with a mantle length of 175 mm (6.9 in), while the other 30 specimens ranged from 146–305 mm (5.7–12.0 in). A Food and Agriculture Organization document lists a maximum mantle length of 780–800 mm (31–31 in). The mantle of this species is stated to be "thick and soft, choroidal", broadest anteriorly (towards the head) and quickly tapering into a "long attenuated tail". The mantle is covered with a thin layer of closely-set non-overlapping "scale-like plates", irregularly pentagonal in shape and 0.5 mm in diameter, which are pale vinous red in color and sparsely scattered with chromatophores. These scales or more accurately "dermal cushions" contain a solution of ammonium chloride, which is known to provide buoyancy in other squid species and likely to provide the same in P. adami. The fins flank the scaled portion of the mantle; they are sagittate (arrowhead-like) in shape, are 3/4 to 4/5 of the mantle's length, and noted to be "quite broad", 60–70% of the mantle length and broadest in the third of the fin towards the front of the animal. The head is narrower than the mantle. The eyes are large and "sunken deeply into the head"; they do not bulge out from the head. The siphon is described as "fairly large but weak", with a slightly sinuous, simple locking apparatus. The gladius is straight-edged, long and slender, with an expanded "vane" ending in a pointed, long and slender conus. The arms are 65–75% of the mantle's length, "long and stout at their bases" and "attenuating" towards their tips; they easily detach from the body similar to the un-scaled skin. The arm bases are said to be one of the few places on the body with visible chromatophores. The third pair of arms, which are the longest arms, has indications of a "swimming membrane" in some specimens, though it is not always apparent. The round, obliquely mounted suckers are arranged in two rows and attached to slender "pedicels". The suckers possess chitinous rings; in the basal suckers these possess triangular "teeth" on the margins away from the arm's bases, while in the middle of the arms these "teeth" are found all around the margins of the sucker. The long and slender tentacles are somewhat flattened, with 4 rows of suckers on non-expanded but very elongated tentacle clubs; the rows of suckers are densest towards the tips of the clubs. The species was noted to possess no hooks or light organs. Live scaled squid are dark red to purple in color.
Taxonomy Though some experts considered this species to be a member of Lepidoteuthidae based on characters of the gladius, separating the two supposed members of Pholidoteuthis (congeners), a later study proved that it is indeed the sister species of Pholidoteuthis massyae, being similar except for P. adami's fins which extend back to form a triangular "tail", with Lepidoteuthis being closer related to the octopus squids (Octopoteuthidae). A 2022 study recovered the two families, grouped into Octopoteuthoidea, in a more basal position than Pholidoteuthis, branching off just before the lineage that led to this genus and the families Chiroteuthidae, Joubiniteuthidae, Magnapinnidae, and Mastigoteuthidae.
Habitat and distribution The holotype was collected 200 fathoms down, at 29°11.5′N 88°07.5′W, off the coast of Texas and east of the Mississippi Delta, while the other specimens collected elsewhere in the upper Gulf of Mexico. This species was subsequently found to range from off Cape Hatteras down to offshore of Río de la Plata; specimens were captured at depths ranging from 360–2,000 m (1,180–6,560 ft) (in the bathyal region), though are most often found 625–750 m (2,051–2,461 ft) down.
Biology This scaled squid is thought to undergo diel migration, as "huge schools" were recorded during nighttime at the surface of the Gulf of Mexico, and they were never recorded by deep-sea trawling during this time. A member of this species was observed in the Exuma Sound in 2013 using an underwater camera platform; a similar platform equipped with a lure mimicking the bioluminescent Atolla jelly would later observe a juvenile giant squid. The observed P. adami was observed to repeatedly attempt to strike giant isopods (Bathynomus giganteus) which were feeding at a bait crate, though it quickly retreated after each strike attempt, before catching any of the isopods. P. adami or a similar species is preyed upon by the short-finned pilot whale, and the sperm whale, which might be the reason why this species mates near the sea floor.
Reproduction
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