A Generic Revision and Phylogenetic Analysis of the Primnoidae

24 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
Diagnosis. Colonies uniplanar, sparsely dichotomously
branched, with long terminal branches. Calyces arranged
in closely placed whorls of up to 10, the appressed
calyces directed upward; calyces cylindrical to cone shaped;
brood chambers common. Poorly developed, almost fl at
operculum present; inner face of opercular scales longitudinally
keeled. Marginal scales not differentiated from other
body wall scales, folding over bases of opercular scales
(Figure 3r). Small calyces covered with eight longitudinal
rows of scales, the adaxial rows somewhat shorter; however,
larger calyces intercalate additional body wall scales,
making the longitudinal row structure indistinct and even
appear to spiral (Figure 3s). Outer face of body wall scales
smooth but with radiating ridges near distal edge, which
interlock with similarly sized ridges on inner distal face of
the more proximal scale, preventing lateral displacement
of scales as calyx opens and closes (Bayer, 1996a). Coen -
enchymal scales in two layers: outermost layer consists of
highly concave, saucer-like plates (Figure 3q), the inner
layer composed of small tuberculate spheroids (Figure 3m).
Discussion. Bayer (1996a) stated that this
genus does not have an operculum; however, calyces from
the type series and even one fi gured by him (Bayer, 1996a:
fi g. 10, bottom) show a distinct, if somewhat ill defi ned,
operculum composed of eight triangular, keeled, opercular
scales.
Distribution. South Georgia and Burdwood
Bank, 70–686 m.
Type Species. A. stefanii Bayer, 1996a, by
original designation. The holotype is deposited at the
USNM (81289).
4. Armadillogorgia Bayer, 1980
FIGURE 4A–G
Armadillogorgia Bayer, 1980:217; 1981b:934 [key to genus].—Bayer and
Stefani, 1989:455 [key to genus].—Bayer, 1996a:527.
Diagnosis. Colonies sparsely dichotomously
branched. Calyces arranged in whorls of up to 20 calyces,
facing upward in the holotype but downward in
other specimens; adaxial side of calyces adnate to branch.
Operculum not present nor are distinctive marginal scales;
calycular aperture (mouth) a simple, unadorned pore (Figure
4b). Polyp completely covered by sclerites, the abaxial
body wall covered by two rows of up to 70 broad, smooth,
sickle-shaped sclerites that meet in an alternating (zigzag)
pattern on calyx midline (Figure 4a, e). Sclerites on adaxial
and circumoral region scale-like but not arranged in rows
or in any order. Coenenchyme composed of two layers of
sclerites, an outer layer of goblet-shaped sclerites (Figure
4f–g) and an inner layer of tuberculate spheroids.
Discussion. Although Bayer (1980) compared
Armadillogorgia to certain species of Primnoella, it
is diffi cult to even consider its placement within the family
Primnoidae. It lacks opercular and marginal scales, its
body wall sclerites are not scales but a uniquely shaped
sickle-like sclerite, its lateral and adaxial sclerites are not
arranged in rows whereas the abaxial rows have up to 70
sclerites, and its sclerites do not demonstrate the characteristic
cruciform extinction pattern under crossed Nicols.
If this is a primnoid, it is a very highly derived genus.
Distribution. South Georgia, Scotia Sea,
659–1,886 m.
Type Species. A. cyathella Bayer, 1980, by
original designation. The holotype is deposited at the
USNM (58166).
5. Ainigmaptilon Dean, 1926
FIGURE 4H–P
Ainigmaptilon Dean, 1926:337.—Carlgren, 1943:1–7.—Bayer, 1950:295–
296 [key to species]; 1956:F222; 1981b:936 [key to genus].—Bayer and Stefani,
1989:455 [key to genus].—Bayer, 1996b:151.
Lycurus Molander, 1929:66–70.
Diagnosis. Colonies unbranched (fl agelliform),
the stem terminating proximally in a funnel-shaped
base, which, when fi lled with mud, functions as an anchor
in soft sediment. Calyces arranged in terminal clusters of
up to 30 on unsupported, simple, or branched fl eshy lobes,
called polyp leaves (Figure 4o, p) by previous authors.
Polyp leaves arranged in an alternate biserially manner on
the branch. Well-developed operculum present, each opercular
having an extremely long, smooth apical spine (Figure
4h–j), so long that they cannot close over the tentacles
of the polyp; inner face of operculars not keeled. Eight
marginal scales present but not differentiated from other
body wall scales, the latter arranged randomly (type species)
or in eight longitudinal rows (e.g., A. edisto). Body
wall scales irregular in shape or triangular shaped, with a
broad, notched distal end (arrowhead shaped; Figure 4m–
n), having a spiny or smooth outer surface. Coenenchymal
plates on branch surface as well as leaf surface fusiform in
shape, having an L:W of up to 10; outer surface smooth,
inner surface tuberculate; no inner layer of specialized coenenchymal
sclerites.