Speirogorgia robertbollandi, Williams, 2019

Williams, Gary C., 2019, A new genus and species of enigmatic gorgonian coral from the Ryukyu Archipelago northwestern Pacific, with a discussion of calcaxonian systematics (Cnidaria Anthozoa, Octocorallia), Zootaxa 4701 (5), pp. 417-433 : 419-426

Speirogorgia robertbollandi sp. nov.

( Figs. 1–8 , 10 )

Species diagnosis. Colonies unbranched, flagelliform/filiform, coiled. Axis quadrate in cross-section. Polyps generally arranged biserially and alternately placed along polypary. Sclerites are tuberculated spindles and capstans. Sclerite color appears white due to lack of pigmentation.

Type material. Holotype. CAS 216391 , East China Sea, Japan, Ryukyu Islands , Okinawa, Seragaki Tombs , 1.3 km ENE Maeki-zaki; 26.00° 30.40’ N 127.00° 52.60’ E; 71.65 m (235 ft.) in depth; 29 April 1995; coll. Robert F. Bolland; originally fixed in 75% ethanol, wet-preserved in 95% ethanol; one colony in two pieces.

Description of the holotype.

External Morphology ( Figs. 1–2 ). The colony is flagelliform and spirally coiled, ca. 400 mm in length and <1 mm in diameter. A holdfast is absent—either the specimen is partial and the holdfast is missing, or the species is “free-living” and lacks a holdfast altogether as is the case in some other filiform gorgonians ( Grasshoff, 1988: 146; 1992: 42).

Axis ( Figs. 3–4 ). The axis is conspicuously quadrangular in shape, highly calcareous, apparently solid and uniform throughout, without concentric lamellae or radiating wedges of calcified material, superficially resembling the calcareous internodes of isidid gorgonians ( Chen, 2011: 76, fig. 7A–B).

Polyps ( Figs. 1–2 ). The polyps are retractile and calyces are absent. The retracted polyps form very low, slightly conical mounds on the surface of the polypary. Many of the polyps form a bilateral appearance, but some are scattered on the polypary surface between the two longitudinal columns. Polyps are separated by bare areas of the polypary, between 2.5 and 3.5 mm in length.

Sclerites ( Figs. 5–8 ). Sclerites of the outer coenenchyme include a predominance of highly warty, elongate spindles with narrow and smooth median waists, often approaching the shape of double cones ( Figs. 5 , 7A ). Other coenenchymal sclerites, particularly from the subsurface coenenchyme include a diverse array of radiates ( Fig.6 , 7B ). Overall coenenchymal sclerite size range: 0.03–0.20 mm—double cones 0.10–0.20 mm, other sclerites 0.03– 0.10 mm ( Figs. 5–7 ). Sclerites of the polyps (presumably those of the tentacles) are small, sparsely-ornamented rods 0.05–0.08 mm in length. The tubercles are not ornate or elaborate, but rather are present as sparsely-distributed, low-rounded to slightly conical mounds or knob-like processes on the sclerite surface ( Fig. 8 ). All sclerites from throughout the colony are colorless.

Etymology. The new species is named for Dr. Robert F. Bolland, who collected the holotype during his time as a professor of biology at the University of Maryland University College Asian Division, Okinawa.

Habitat and distribution ( Fig. 10 ). Mixed sand and coral rubble. At present known only from the type local-ity—Okinawa, Ryukyu Islands, Japan, 72 m in depth.

Differential diagnosis. Speirogorgia differs from all other calcaxonian taxa in that it possesses distinctive coenenchymal sclerites that predominantly resemble double cones, as well as a filiform growth form, completely retractile polyps without calyces, and has a uniform axial interior throughout. Isidids have jointed axes with alternating proteinaceous nodes and calcareous internodes. Primnoids and chyrsogorgiids have non-retractile polyps, well-spiculated polyp bodies, and sclerites that are mostly plates, scales, or rods with sparse ornamentation. The el- lisellid and pennatulacean sister groups have radiating wedge-shaped columns of calcareous material that comprise the axis. The ifalukellids have a bushy or plumose growth form, and small scale-like, often oval sclerites with a course, granular surface texture.

Comparisons. A monotypic taxon.

Figures

FIGURE 1. Speirogorgia robertbollandi gen. & sp. n. A. Two photographic views of the entire holotype; scale bar=45 mm. B–C. Dissecting microscope views of external morphology. B. Two views of a portion of the colony showing placement of polyp mounds; scale bar=2.50 mm. C. Details of surface of colony showing polyp mounds and partially exserted polyps; scale bar=2.50 mm.

FIGURE 2. Speirogorgia robertbollandi gen. & sp. n. A. Scanning electron micrograph of a portion of the polypary showing a single polyp mound, and sclerites of the surface coenenchyme; scale bar=0.4 mm. B–C. Two photographic views of a portion of the polypary; scale for B=1.0 mm; scale bar for C=2.5 mm.

FIGURE 3. Speirogorgia robertbollandi gen. & sp. n. Scanning electron micrographs of morphological features. A. A portion of the external surface of the holotype showing a polyp mound (center) and dense arrangement of sclerites in the surface coenenchyme; scale bar=1.0 mm. B–D. Oblique views of portions of the axis showing distinctive quadrangular shape in transverse section, and solid calcified material distributed throughout the axial interior; scale bars=0.2 mm.

FIGURE 4. Speirogorgia robertbollandi gen. & sp. n. Scanning electron micrographs of axial structure. A–B. Longitudinal views of two portions of axis; scale bar=1.0 mm. C. Transverse section of axial portion in A; scale bar=0.2 mm.

FIGURE 5. Speirogorgia robertbollandi gen. & sp. n. Scanning electron micrographs of sclerites from the surface coenenchyme—elongated spindles with median waists; scale bar=0.10 mm.

FIGURE 6. Speirogorgia robertbollandi gen. & sp. n. Scanning electron micrographs of sclerites from the subsurface coenenchyme—radiates; scale bar=0.05 mm.

FIGURE 7. Speirogorgia robertbollandi gen. & sp. n. Scanning electron micrographs of coenenchymal sclerites. A. Sclerites from the surface coenenchyme. B. Sclerites from the subsurface coenenchyme; scale bar=0.05 mm.

FIGURE 8. Speirogorgia robertbollandi gen. & sp. n. Camera lucida illustrations of polyp sclerites (rod-like structures presumably from the tentacles); scale bar=0.02 mm.

FIGURE 10. Map of a portion of the eastern Pacific, Ryukyu Archipelago, and Okinawa; arrows point to the type locality of Speirogorgia robertbollandi gen. & sp. n.