Octocorallia, Haeckel, 1866

Devictor, Susan T. & Morton, Steve L., 2010, Identification guide to the shallow water (0 - 200 m) octocorals of the South Atlantic Bight 2599, Zootaxa 2599 (1), pp. 1-62 : 13-17

Key to Families (and unique species) of Octocorallia of the South Atlantic Bight (to 200m)

Subclass Octocorallia

1. Colonies attached to substrate with a basal disc or holdfast ( Figure 9a,b ), or encrusting ( Figure 9c ). Colonies generally moderately branching to highly arborescent (although a few species may be unbranched). No leaf-like structures. Coenenchymal sclerites present in all species; medullar or axial sclerites present in some species .................... ................................................................................................................................................. Order Alcyonacea .... 2

- Colonies with a basal muscular peduncle for anchoring in soft substrate ( Figure 10a,b ). Growth form foliose, bilateral, whip-like or club-like, but not branching or encrusting, sometimes with leaf-like structures on the rachis ( Figure 10c,d ). Sclerites usually present in form of three-flanged rods, plates or needles, never spindles, but absent in axis ..................................................................................................................................... Order Pennatulacea … 9

2. Colonies containing a horny ( Figure 11a,b ) or highly calcified ( Figure 11c ) axis, or distinct spiculated medular region ........................................................................................................................................................................... 3

- Colonies containing no horny or highly calcified axis or distinct spiculated medular region (although tissue may occasionally encrust dead octocoral colonies [see Figure 28B ]) ................................................................................. 6

3. Octocorals with axial structure (medulla) composed of free sclerites. Stem divided into outer cortex and inner spiculated medulla, with ring of boundary canals between (see Figure 7 ) ............................................................................. ....................................................................................................... Suborder Scleraxonia … Family Anthothelidae

- Octocorals with axial structures not composed of free sclerites; horny axis with a distinct hollow, cross-chambered core ( Figure 11a ,b') or highly calcified axis with no hollow core ( Figure 11c ) ........................................................... 4

4. Colonies with a horny axis containing a hollow, cross-chambered central core ................. Suborder Holaxonia … 5

- Colonies with highly calcified axis with no hollow, cross-chambered inner core.......................................................... ............... Suborder Calcaxonia , Family Ellisellidae … Viminella barbadensis ( Duchassaing & Michelotti, 1864)

5. Coenenchyme contains some large (0.3–2.0 mm) sclerites, including spindles ( Figure 12a,b ), double-heads ( Figure 12c ), rosettes, cups ( Figure 12d ), knobbed stars or plates ( Figure 12e,f ), thorn-scales ( Figure 12g,h ). Axis typically loculated ( Figure 12i ). Calyces often very prominent, appearing spiky, conical ( Figure 12j ), cylindrical ( Figure 12k ) or shelf-like ( Figure 12l ) .............................................................................................................. Family Plexauridae

- All sclerites small (<0.2 mm), including warty spindles ( Figure 13 a-c), capstans, ( Figure 13d,e ) and flattened rods ( Figure 13f,g ), generally symmetrical, except for sometimes having partially fused disks ( Figure 13h,i ). Axis unloculated or minimally so ( Figure 13j ). Calyces absent, but polyp mounds may be moderately prominent, hemispherical ( Figure 13k ) or absent when polyp is retracted ( Figure 13l ) ...................................................... Family Gorgoniidae

6. Encrusting colonies, or branching colonies with a primary polyp and budded lateral daughter polyps ( Figure 14a ) arising from sheet-like, ribbon-like ( Figure 14b ), or reticulating stolons. Calyces long, cylindrical, with retractile polyps ( Figure 14a,b ) ................................................................................................................ Family Clavulariidae

- Soft corals with fleshy stalk and/or base, not encrusting and without a primary polyp from which all daughters arise; colonies moderately arborescent, lobed, capitate, digitiform or club-like. Polyps often in clusters ( Figure 15 ) ........... ........................................................................................................................................... Suborder Alcyoniina … 7

7. Colony digitiform ( Figure 15c ); polyps not restricted to clusters, but scattered around the colony ............................. ............................................................................. Family Alcyoniidae … Bellonella rubistella ( Deichmann, 1936)

- Colony capitate, lobed or arborescent; polyps occurring in clusters at ends of stalk or lobes ( Figure 15a,b ) ........... 8

8. Colonies non-branching, torch-like or capitate, with long, stiff stalk ( Figure 15b ). Sclerites long, slender, 6 times longer than wide .................................................................. Family Nidaliidae … Nidalia occidentalis Gray, 1835

- Colonies lobed or slightly arborescent, with polyp clusters on terminal lobes ( Figure 15a ). Sclerites in the form of foliated clubs and tuberculate rods ............................ Family Nephtheidae … Pseudodrifa nigra ( Pourtalès, 1868)

9. Colony foliose or heart-shaped, with polyps on upper surface. Sclerites rod-like. No axis........................................... ............................................................................................. Family Renillidae … Renilla reniformis ( Pallas, 1766)

- Colony slender, elongate, pen-like ( Figure 16a ), whip-like, or club-like ( Figure 16b ), often with naked dorsal groove or track ( Figure 16c ). Sclerites, when present, as scales ( Figure 16d ) or needles ( Figure 16e ). Axis always present .................................................................................................................................................................................... 10

10. Colonies pen- or whip-like, with autozooids arranged in polyp leaves ( Figure 16a,c,e ) along sides of axis................. .................................................................................................................................................... Family Virgulariidae

- Colonies club-like, without polyp leaves, with autozooids scattered or in rows on rachis ( Figure 16b ) …...................................................................... Family Kophobelemnidae .... Sclerobelemnon theseus Bayer, 1959

Figures

FIGURE 7. A, Transverse and B, longitudinal cross-sections of scleraxonian octocoral axis (Diodogorgia nodulifera), showing inner cortex (In. cor.), outer cortex (Ou. cor.), spiculated medulla (Me), polyps (Pol), and ring of boundary canals (Bo. ca.).

FIGURE 9. a) Pseudodrifa nigra, basal disc indicated; b) holdfast of Muricea pendula; c) encrusting colony of Scleranthelia rugosa (from Bayer 1981a).

FIGURE 10. a) Sclerobelemnon theseus peduncle indicated; b) Renilla reniformis, peduncle indicated; c) Virgularia presbytes, leaf-like structures indicated; d) Stylatula elegans, showing two polyp leaves (modified from Bayer, 1958).

FIGURE 11. a) Longitudinal section of gorgoniid branch, horny axis with hollow, cross-chambered central core indicated; b, b') cross section of plexaurid branch, horny axis (b) and hollow core (b') indicated; c) cross-section of ellisellid branch, highly calcified axis indicated. Illustration a from Bayer, 1961; illustrations b and c modified from images in Fabricus and Alderslade, 2001).

FIGURE 12. a) Scleracis guadalupensis spindle; b) Thesea nivea spindle and c) double head; d) Bebryce parastellata cup-shaped sclerite and e) knobbed plate; f) Bebryce cinerea knobbed plate; g, h) Paramuricea sp. thornscales; i) crosssection of plexaurid branch, loculi within axis indicated; j) Scleracis guadalupensis conical calyces; k) Bebryce parastellata cylindrical calyces; l) Muricea pendula shelf-like calyx. Illustrations d and e modified from images by S. Cairns/ Smithsonian Institution; illustration i modified from image in Fabricus and Alderslade, 2001; illustration l modified from image by FM Bayer/Smithsonian Institution.

FIGURE 13. a, b) Leptogorgia cardinalis spindles; c) Leptogorgia virgulata spindle; d) Leptogorgia hebes capstan; e) Leptogorgia punicea capstan; f) Leptogorgia cardinalis rod; g) Leptogorgia hebes rod; h, i) disc spindles of Leptogorgia setacea; j) cross-section of gorgoniid branch, unloculated axis indicated; k) hemispherical polyp mounds of Leptogorgia euryale; l) branch of Leptogorgia setacea with no polyp mounds.

FIGURE 14. a) Telesto sanguinea colony, daughter polyps indicated; b) Scleranthelia rugosa, encrusting, ribbon-like stolon indicated (from Bayer, 1981a).

FIGURE 15. a) Pseudodrifa nigra; b) Nidalia occidentalis (from Bayer, 1961); c) Bellonella rubistella.

FIGURE 16. a) Virgularia presbytes; b) Sclerobelemnon theseus; c) dorsal streak of Virgularia presbytes; d) scale sclerites of Sclerobelemnon theseus; e) polyps of Stylatula elegans, needle sclerites indicated (modified from Bayer, 1958).

FIGURE 28. Scleranthelia rugosa: A, plate sclerite of var. musiva (USNM 54586) (scale bar = 0.1 mm); B, calyx of var. musiva (USNM 55107) (scale bar = 0.5 mm); C, var. rugosa showing ribbon-like stolons (USNM 94534, preserved specimen); D, var. rugosa, close up of calyx, showing stolon and plate sclerites; E, var. musiva, showing sheet-like stolons (USNM 55540, preserved specimen). A and B SEM images by F.M. Bayer/Smithsonian Institution.