A Generic Revision and Phylogenetic Analysis of the Primnoidae

48 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
Diagnosis. Branching of colonies in a bottlebrush
arrangement. Calyces arranged in whorls of up
to fi ve, the calyces inclined upward (Figure18i). Welldeveloped
operculum present, the operculars prominently
keeled (Figure 18n) on their inner surface. Five marginal
scales (Figure 18j) present, all bearing apical spines, but
abaxial and two lateral marginals bear extremely long
spines. Marginal spines bear longitudinal serrate ridges.
Polyps completely covered by fi ve longitudinal rows of
body wall scales (one abaxial row, two lateral rows, and
two adaxial rows, the adaxial scales much smaller than
the others). Inner surface of body wall scales tuberculate
(Figure 18m), outer surface fi nely granular (Figure 18l).
Coenenchymal scales elliptical, arranged in one layer.
Discussion. Originally considered by Versluys
(1906) to be one of four subgenera of Stenella sensu
Gray, 1870, Dasystenella was raised to generic rank by
Bayer (1981b), who distinguished it as having only fi ve
marginal scales and bottlebrush-branched colonies. It is a
monotypic genus restricted to the subantarctic region.
Distribution. Argentina, Scotia Ridge to
South Shetland Islands, abyssal plain west of Tierra del
Fuego, 300–5,087 m.
Type Species. Stenella acanthina Wright and
Studer, 1889, by monotypy. Syntypes are deposited at
the BM (1889.05.27.48), and uncataloged syntype SEM
stubs B276 and C1185-1186 are deposited at the NMNH.
The type species was recently redescribed and fi gured by
Cairns (2006).
41. Pseudoplumarella Kükenthal, 1915
FIGURE 19A–J
Plumarella.—Thomson and Mackinnon, 1911:682 [in part: not P. laevis].
Pseudoplumarella Kükenthal, 1915:143, 145 [in part: not P. plumatilis, key
to genus and species]; 1919:353–354 [in part: not P. plumatilis, key to genus
and species]; 1924:263 [key to genus and species].—Bayer, 1956:F220;
1981a:622–625; 1981b:937 [key to genus].—Bayer and Stefani, 1989:454
[key to genus].
Diagnosis. Colonies uniplanar, branching in
an alternate pinnate manner. Calyces small, arranged in
an alternate biserial manner on distal branches, becoming
random (Figure 19a) on larger branches; calyces face
upward and are adnate to branch, such that there is essentially
no adnate body wall. Well-developed, tall, conical
operculum present, operculars bearing a prominent
longitudinal keel (Figure 19d–e). Lower, inner edge of
each abaxial and outer-lateral operculars bear two irregularly
shaped mounds, one on either side of the midline,
each of which articulates with the mound on the adjacent
opercular (Figure 19c–e), producing a strong interlocking
of adjacent operculars (sometimes joined even after the
cleaning treatment). Inner-lateral operculars have only
one mound on the abaxial side, and adaxial operculars do
not have articulating mounds at all. Usually, fi ve marginal
scales present, those on the abaxial may be spinose, but in
most species (e.g., the type species) not. Polyp protected
by three longitudinal rows of body wall scales: a single
row of smooth, large, crescent-shaped abaxial body wall
scales (Figure 19h–i) and two outer-lateral rows of about
four scales each; inner-lateral and adaxial positions usually
limited only to marginal scales (i.e., no rows). Coenenchymal
scales in two layers: outer layer composed of
smooth scales, inner layer composed of small irregularly
shaped tuberculate rods.
Discussion. Characters used to distinguish
the fi ve species (Table 4) include number of scales in the
abaxial body wall rows, serration or lack thereof on distal
margin of abaxial scales, spination of marginal scales, and
arrangement of calyces on branch.
The outer-lateral row of the type species consists of
a medium-sized marginal scale, two small scales hidden
by their adjacent abaxial scales, and a massive basal scale
that partially overlaps the basalmost abaxial scale. The
opercular locking mechanism appears to be unique among
the primnoids.
Distribution. Off New South Wales and
Queensland, Australia, 55–115 m.
Type Species. Plumarella thetis Thomson and
Mackinnon, 1911, by original designation. Syntypes are
deposited at the AM, the specimen from Thetis station 40
numbered G12137.