Grasshoffia virgularioides, Williams, Gary C., 2015

Williams, Gary C., 2015, A new genus and species of pennatulacean octocoral from equatorial West Africa (Cnidaria, Anthozoa, Virgulariidae), ZooKeys 546, pp. 39-50 : 41-44

Taxon classification Animalia Pennatulacea Virgulariidae

Grasshoffia virgularioides sp. n. Figures 1, 2, 3, 4, 5

Species diagnosis.

Virgulariid sea pens superficially resembling some species of Virgularia . Axis circular in transverse section, extending throughout virtually entire colony length. Polyp leaves variously rolled, funnel-shaped, or semicircular in shape with conspicuous, somewhat narrowed basal stalks. Sclerites of polyps leaves and coenenchyme rod-like with parallel sides and mostly deltoid apices, inconspicuously three-flanged. Preserved colony color cream-white in ethanol.

Type material.

Holotype: USNM 1205583, North Atlantic Ocean, Gulf of Guinea, Nigeria, Isaka, Bight of Bonny, Niger Delta, Bonny River; depth not recorded; 28 August 1984; wet-preserved 70% ethanol; one whole colony. Paratype 1: USNM 1231549, same data as holotype; one colony in two pieces 122 mm in total length. Paratype 2: USNM 1231550, same data as holotype; one colony 82 mm in length. Paratype 3: USNM 1205580, same data holotype; one colony in two pieces 119 mm in total length.

Description.

Morphology (Figures 1-2). The holotype is 98 mm in length. The axis extends throughout the length of the colony and is exposed for 5 mm at the distal-most region of the rachis. The axis is circular to broadly elliptical in cross section (Figure 2C), mottled brown and white in color (presumably due to a mixed content of calcitic and proteinaceous material), composed of narrow wedges of axial material radiating outward from the center, and is approximately 0.80-0.90 mm in diameter. The rachis is also approximately 0.80-0.90 mm in width and is densely congested with polyp leaves; there is approximately 1.5 mm of bare rachis between adjacent proximal bases of the polyp leaves. The polyp leaves are funnel-shaped or mushroom-shaped in lateral view. They broaden distally where the polyps reside, and have neck-like bases that narrow proximally and serve to attach the polyp leaves to the rachis (Figure 2B). The appearance of the polyp leaves are conspicuously rolled or convoluted (some are horseshoe-shaped), with approximately fourteen to twenty-six polyps per leaf (Figures 1A, 2A). The polyps are contractile and non-retractile, urn-shaped or teardrop-shaped and approximately 0.50-0.60 mm in diameter. Siphonozooids not apparent on the rachis or polyp leaves.

Sclerites (Figures 3-4). The distal region of the polyp leaves and the tissues of the peduncle contain numerous, small, rod-like sclerites that are prismatically-shaped with straight parallel sides, more-or-less three-flanged, mostly broadly-triangular in shape at each end, and vary in length from 0.02 to 0.06 mm.

Color (Figure 1). The color of the wet-preserved colonies is cream-white throughout.

Etymology.

The specific epithet is derived from the genus Virgularia and the suffix -oidea (likeness of form); in reference to the superficial resemblance of the colonies to some species of the genus Virgularia .

Habitat and distribution.

Habitat not known. Known only from the type locality - Niger River Delta, Nigeria, Gulf of Guinea, West Africa. Depth not recorded (Figure 5).

Differential diagnosis.

Virgularia and Scytaliopsis do not have sclerites in the rachis or polyp leaves. Scytalium has ovoid plate-like sclerites in the polyp walls and polyp leaves that are not three-flanged. Grasshoffia has prismatically-shaped rod-like sclerites in the polyp leaves and coencenchyme that are indistinctly three-flanged and have broadly-triangular ends. Species of Stylatula have a fan-like armature of large spindles at the base of each polyp leaf, and most species of Acanthoptilum have a cluster of non-aligned spindles at the base of each polyp leaf. Virgularia , Scytalium , Stylatula , and Acanthoptilum generally have flattened polyp leaves that are variously-shaped, while Grasshoffia has strongly curved, rolled, often horseshow-shaped to funnel-shaped polyp leaves. Stylatula macphersoni López-González, Gili & Williams, 2001, has sclerites in the body walls of the autozooids that are similar in shape to coenenchymal sclerites in Grasshoffia virgularioides ( López-González et al. 2001; 67, Fig. 4A).

Remarks.

The coenenchyme covering the rachis is extremely thin, and therefore the rachis and axis diameters are virtually equal. The polyp leaves are distinctly rolled or conspicuously curved, perhaps due to contraction in the wet preserved type material, as the appearance of the living colonies is not known. Siphonozooids were not observed in the preserved type material, possibly due to the congested and contracted state of the polyp leaves along the rachis.