Keratoisis fruticosa, Lapointe & Watling, 2022

Lapointe, Abby & Watling, Les, 2022, Towards a revision of the bamboo corals (Octocorallia): Part 5, new genera and species of Keratoisididae from the Tasmanian deep sea, Zootaxa 5168 (2), pp. 137-157 : 141-145

Keratoisis fruticosa new species

Figures 3–8

Material Examined. Holotype: TMAG K3832 , The Finger, Tasman Fracture Zone, Tasmanian Seamounts , 10 January 2009, -45.2949, 146.1144, 2423 m, 2.07° C bottom temp.

Paratypes: TMAG K3837 , St. Helens, Tasmanian Seamounts , 01 January 2009, -41.2395, 148.8221, 1286 m , 3.37° C bottom temp. TMAG K3851 , The Finger, Tasman Fracture Zone, Tasmanian Seamounts , 10 January 2009, -45.3004, 146.1025, 2217 m , 2.14° C bottom temp. TMAG K3850 , St. Helens, Tasmanian Seamounts , 01 January 2009, -41.2397, 148.8206, 1355 m , 3.07° C bottom temp. TMAG K3836 and K3848, Mongrel / South Hills, Tasmanian Seamounts , 21 December 2008, -44.2933, 147.6333, 1123 m . TMAG K3844 , Tasman Fracture Zone, Tasmanian Seamounts , 09 January 2009, -45.3697, 144.6031, 2727 m , 1.73° C bottom temp. TMAG K3838 , South Hills, Tasmanian Seamounts , 21 Dec 2008, -44.2933, 147.6333, 1060 m , 4.15° C bottom temp.

Diagnosis. Colony is bushy in appearance, branching irregularly at the internodes, occasionally with nodes at the origin of the branch. Secondary calcification occurs over most of the axis. Sclerites in the polyp body are needles or rods arranged obliquely, longitudinally, and occasionally horizontally at the base. Septal sclerites are arranged in groups or as single longitudinal needles.

Description of holotype. Branching pattern is irregular. Colony branches at the internodes, but a node might be present at the origin of the branch ( Fig. 3A ). The axis is approximately 15 mm in diameter at the base of the colony, and decreases to 1 mm at the distal branches. The axis core is hollow, pin-sized throughout the entire colony, independent of the diameter of the axis.

Internodes range from 32 to 59 mm in length. Polyps are located on all sides of the axis, separated by obvious coenenchyme tissue. Polyps are tall (~ 1 cm) and columnar, with a similar diameter throughout ( Fig. 3C, D ). Sclerites in the polyp body are rods and needles, and may be straight or slightly curved, ranging in length from 0.55 to 4.0 mm. Sclerites are arranged obliquely and longitudinally throughout the polyp body, and occasionally horizontally at the base ( Figure 3C, D ). Rods and needles have longitudinal grooves and tuberculate ends ( Fig. 4A ). Scales are not present.

Septal sclerites are needles arranged in groups or singly, perpendicular to the polyp axis, and flare outward slightly when tentacles are contracted. When contracted, tentacles fold slightly inward with tips touching, or fold over slightly toward the center of the polyp ( Fig. 3C ). Tentacular sclerites are rods and flat rods, ranging from approximately 0.29 to 0.75 mm ( Fig. 4C ). The larger rods are arranged longitudinally along the tentacles, decorated with grooves, and have rounded ends with numerous tubercles. The pinnules contain smaller flat rods, 0.10 to 0.15 mm, also decorated with longitudinal grooves and numerous tubercles.

Sclerites of the pharynx are irregularly toothed rods, with a heavily textured surface decorated with longitudinal grooves and multiple tubercles ( Fig. 4D ). Lateral teeth may be gently rounded or triangular. Pharyngeal sclerites range in length from approximately 0.07 to 0.10 mm, and two sclerites may occasionally be fused together. Sclerites in the form of rods, similar in size and shape to sclerites in the polyp body, are sparsely and irregularly arranged throughout the coenenchyme ( Fig. 4B ).

Variation of paratypes. All specimens examined and designated as paratypes had genetically identical sequences for the gene mtMutS. Axis internodes vary significantly in length, both within and between the specimens collected. Internodes are most frequently between 30 and 50 mm in length, but there is great variation in distance between nodes, ranging from 18 to 70 mm. In specimen TMAG K3851, several portions of the axis form anastomoses.

Needle sclerites in the polyp body and coenenchyme are often straight, but most of the specimens collected commonly have curved sclerites in these areas ( Fig. 5 ). In TMAG K3837, flat rods were also found irregularly arranged in the coenenchyme, similar in shape and decoration to the flat rods in the tentacles, but slightly larger ( Fig. 6 ). Tentacular sclerites always consist of rods and flat rods, although the larger rods may vary slightly in shape ( Fig. 7 ). Some may have a pronounced club appearance, while others may be wider in the middle than at the ends. Specimens TMAG K3848, TMAG K3850 and TMAG K3844 have pharyngeal sclerites similar in size and shape to the other specimens collected, but with several very sharp extensions protruding from the sclerites ( Fig. 8 ).

Etymology. The name based on the Latin adjective fruticosum, = bushy or shrubby, a reference to the general appearance of the colony.

Remarks. This species is unique in the genus Keratoisis as the branching pattern is highly variable, with branches at the internodes, but with nodes at the origin of some of the branches. Interestingly, that mode of branching was also illustrated for K. grayi by Bayer (1956). This species also demonstrates high variability in the sclerite shape, in particular in the body and coenenchyme. Various invertebrates tend to be associated with this species. An anemone was growing on one of the branches of TMAG K3837 and was included in the specimen collection. TMAG K3850 was collected growing on the dead skeleton of a scleractinian coral, Solenosmilia variabilis .

Figures

FIGURE 3. Keratoisis fruticosa n. sp., holotype, K3832, A, all collected and preserved colony pieces, B, in situ view of colony being collected, C, D, views of individual polyps.

FIGURE 4. Keratoisis fruticosa n. sp., holotype, K3832, sclerites from, A, polyp body, B, coenenchyme, C, tentacles, and D, pharynx.

FIGURE 5. Keratoisis fruticosa n. sp. body sclerites of paratype specimens, A, K3837, B, K3851, C, K3850, D, K3836, E, K3838, F, K3844.

FIGURE 6. Keratoisis fruticosa n. sp. coenenchyme sclerites of paratype specimens, A, K3837, B, K3851, C, K3850, D, K3836, E, K3838, F, K3844.

FIGURE 7. Keratoisis fruticosa n. sp. tentacle sclerites of paratype specimens, A, K3837, B, K3851, C, K3850, D, K3836, E, K3838, F, K3844.

FIGURE 8. Keratoisis fruticosa n. sp. pharyngeal sclerites of paratype specimens, A, K3837, B, K3851, C, K3850, D, K3836, E, K3838, F, K3844.