Porcupinella tasmanica, Williams, 2021
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Mature colony length < 50 mm. Lower rachis region strongly recurved, colonies have an inverted J-shape. Region of strongest curvature forms a laterally flattened keel. Single terminal polyp and generally two pair of lateral polyps congested together in distal region of rachis. Autozooids five to seven in total number. Distal terminus of colony ends in a pointed tip and may form a downward projecting beak-like acute point. Siphonozooids sparsely distributed (< 12 per side), present on upper surface of rachis adjacent and proximal to the lower lateral polyps. Sclerites restricted to minute ovoid bodies in the bulb of the peduncle. Preserved colonies white.
Holotype. CASIZ 228434. Western Pacific Ocean, Australia, Tasman Sea, Flinders Marine Park (40.4732 to 40.464S, 149.3967 to 149.4255E); 4114-4139 m; 20 May 2017; coll. RV Investigator, IN2017_V03_015_011, Beam Trawl; one whole colony wet-preserved in 95% ethanol. Paratype. CASIZ 228435, same data as holotype; one whole colony wet-preserved in 95% ethanol.
CASIZ 228436, same data as holotype, three whole colonies wet-preserved in 95% ethanol.
Habitat and distribution.
Known only from the type locality, Flinders Marine Park in the Tasman Sea, 4114-4139 m in depth (Fig. 6A, B View Figure 6 ).
The specific epithet is derived from “Tasmania” and the Latin suffix - ica (belonging to), in reference to the type locality.
Description of the holotype.
(Figs 1 View Figure 1 , 2A View Figure 2 ). Colonial morphology . The holotype is 30 mm in length from proximal tip of the peduncle to the distal margin of the keel. If the length of the recurved distal portion of the rachis is included, the total length of entire colony is approximately 46 mm. The keel represents that portion of the colony between the polyp-bearing portion of the rachis and the distal most portion of the peduncle. The keel is somewhat flattened laterally. The maximum height of the keel is approximately 2 mm in the region of strongest curvature. The thin internal axis is clearly distinguishable just below the surface of the upper-most portion of the keel curvature. The distal terminus of the rachis comes to an acute tip and is beak-shaped. The rachis is widest in the middle and tapers at both ends. The peduncle occupies approximately 20 mm of the colony below the proximal portion of the keel. The narrowest part of the peduncle is 0.5 mm in diameter and the widest part is the proximal bulb, approximately 1.5 mm in diameter.
Polyps (Figs 1 View Figure 1 - 3 View Figure 3 ). The lower pair of lateral polyps (autozooids) emanate from opposite sides of the widest part of the rachis, while the bases of the upper pair of lateral polyps are closer together on the narrower distal portion of the rachis. The single terminal polyp emanates from 1-2 mm proximal to the acute tip of the beak near the distal terminus of the colony. The siphonozooids appear as minute, low, hemispherical mounds (<0.2 mm in diameter), and are sparsely distributed on all sides of the rachis from the upper-most portion of the keel to just below the insertion of the terminal polyp. A few siphonozooids are also distributed along the lateral surfaces of the strongly curved portion of the keel, adjacent to the outline of the subcutaneous axis.
Sclerites (Fig. 2 View Figure 2 inset). Sclerites are apparently absent throughout the colonies except in tissues of the peduncle, in which there are minute, variably shaped, mostly ovoid bodies, 0.01-0.02 mm in length. These sclerites are difficult to isolate and observe. Sclerites were not observed in other parts of the colony. This is similar to what has been recorded in the type species of the genus, Porcupinella profunda ( López-González & Williams, 2011: 313.).
Variation. (Figs 2 View Figure 2 , 3 View Figure 3 ). The five colonies that are known to exist are all from the same collecting station and collecting event in the Tasman Sea. They have an a more-or-less inverted fish hook shape or inverted J-shape and range in length from 27-38 mm (Figs 1 View Figure 1 , 2 View Figure 2 ). The strongly curved portion of the upper stalk is laterally compressed and flattened, forming a conspicuous keel, with a narrow portion of the axis running throughout the upper-most portion of the curved keel (Figs 1 View Figure 1 , 2 View Figure 2 ). The axis is present throughout the length of the colonies, and is discernably wider in the peduncle than in the rachis or polyp-bearing upper portion of the stalk, where it is relatively narrow. The proximal end of the short peduncle is somewhat [slightly] swollen and forms an elongated bulb (Figs 1 View Figure 1 , 2 View Figure 2 ). The total number of autozooids in any given colony is generally five to seven - one terminal polyp and four to six lateral polyps. The siphonozooids are not conspicuous and are relatively sparsely distributed on parts of the rachis and distal portion of the keel (Figs 1 View Figure 1 , 3A, B View Figure 3 ). The distal portion of the stalk that contain the polyps is spearhead-shaped or spade-shaped, and ends with an acutely tipped, generally curved beak (Figs 1 View Figure 1 , 2C View Figure 2 ). A single terminal polyp emanates from the base of the beak. Two pairs of lateral polyps are oppositely disposed on the spearhead-shaped upper portion of the stalk. (Figs 1 View Figure 1 - 3 View Figure 3 ). Conspicuous sclerites are absent in all parts of the colony, with the exception of minute oval bodies in the peduncle interior. Color of the preserved colonies is white throughout (Figs 2 View Figure 2 , 3 View Figure 3 ).
Porcupinella tasmanica has a strongly recurved growth form, and the autozooids are on the enlarged rachis, which is distal to the keel and separated from it (Figs 1 View Figure 1 , 2 View Figure 2 ). This is in contrast to the only other known species, Porcupinella profunda , which is slightly crescent-shaped to virtually straight, the keel and the rachis are not separated, and the autozooids are contained on the sides of the keel/rachis region (Figs 4 View Figure 4 , 5 View Figure 5 ).
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