1. 64 Accepted by D. Calder: 13 Oct. 2011; published: 21 Nov. 2011
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)Copyright © 2011 · Magnolia Press
Zootaxa 3104: 64–68 (2011)
www.mapress.com/zootaxa/ Correspondence
A new sclerite-free genus and species of Clavulariidae (Coelenterata:
Octocorallia)
PHILIP ALDERSLADE1
& CATHERINE S. MCFADDEN2
1
Commonwealth Division of Marine & Atmospheric Research, PO Box 1538, Hobart, Tasmania 7001, Australia. E-mail:
phil.alderslade@csiro.au
2
Department of Biology, Harvey Mudd College, Claremont, California 91711, USA. E-mail: mcfadden@hmc.edu
This short communication describing only a single new taxon is necessary to facilitate further research publications by
Neil Blackstone & Austin Parrin (Northern Illinois University) and colleagues. Neil and Austin have found the new
species to be an ideal experimental animal that is fast-growing and extremely easy to maintain in laboratory aquaria
(Parrin et al. 2010). [NTM = Museum & Art Gallery of the Northern Territory, PO Box 4646, Darwin, NT 0801,
Australia].
Clavulariidae Hickson, 1894
Clavulariinae Roxas, 1933
Phenganax, n. gen.
Diagnosis: Clavulariinae with an encrusting, stoloniferous habit. Polyps erect, separate from each other, upper part
retractile into basal part, not into stolon. Stolons and basal part of polyps covered in a thin cuticle. Sclerites absent;
zooxanthellae present. Distribution tropical. Type species: Phenganax parrini, n. sp., by original designation and
monotypy. Etymology: utilising the transliterated Greek words phengos, meaning light, and anax, meaning master or
king (see “Aquarium notes” below). Gender neuter. Cervera Làpez-González et al., 1995, is the only stoloniferous genus
with comparable features to the new taxon. It has the same basic colony form, but it lacks zooxanthellae, has a cryptic,
temperate habitat, and a very different DNA profile.
Molecular data: DNA sequences from two mitochondrial coding regions, cytochrome oxidase I and the octocoral-
specific mut-S homolog (GenBank accessions GQ342412 and GQ342490), were compared to reference sequences from
81 octocoral genera representing 28 of 47 families, including eight genera of Clavulariidae and three other families of
stoloniferans (Acrossotidae, Coelogorgiidae, Tubiporidae). Phylogenetic analyses support a sister relationship between
Phenganax parrini, n. g., n. sp., and Acrossota amboinensis (Acrossotidae), although the genetic distance separating
them is comparable to that among other stoloniferan genera that have been placed in different families or sub-families.
Family Clavulariidae is highly polyphyletic (McFadden et al. 2006), and Phenganax, n. gen., belongs to a clade that is
phylogenetically distant from the morphologically similar Cervera (GenBank accessions JN620804 and JN620805).
Phenganax parrini, n. gen, n. sp.
Figs 1–2
?Clavularia reptans, sensu Thomson & Henderson 1906: 403.
clavulariid sp. A., Parrin et al. 2010: 113–120.
Material examined: Holotype, NTM C015597, Bali, Indonesia, Daniel Knop via a German importer, kept in an
aquarium for only a short time, 2009. Paratypes: NTM C015598, origin unknown, aquarium raised, Austin Parrin & Neil
Blackstone via a US importer, 2009; NTM C015599, same data except 2006.
Description: The holotype has a stoloniferous mode of growth and encrusts many parts of a fragment of dead, finely
branched scleractinian coral (Acropora sp.). In the aspect shown in Fig. 1A, it measures 45 mm between the arrowhead-
labels.

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FIGURE 1. Phenganax parrini, n. g., n. sp., holotype: A, whole colony; B,D, close-ups; C, gap-bridging stolon with a polyp; E, oral
aspect of a polyp. s = stolon, e = expanded polyp, r = retracted polyp.

3. ALDERSLADE & MCFADDEN66 · Zootaxa 3104 © 2011 Magnolia Press
FIGURE 2. Phenganax parrini, n. g., n. sp., colonies in an aquarium: A, dense polyps obscuring substrate; B-C, a selected colony
portion in two different states of polyp activity; D, a polyp with a wrinkled cuticle on the basal portion; E, a polyp fully expanded
[pharynx (p)]; F, same polyp partially retracted.

4. Zootaxa 3104 © 2011 Magnolia Press · 67CLAVULARIIDAE—A NEW SCLERITE-FREE TAXON
Polyps are monomorphic and the distribution varies from well spaced to dense clumps (Fig. 1B, D). Polyps arise
from anastomosing stolons that criss-cross the substrate, and bridge gaps between branches (Fig. 1Bs, Ds). Figure 1C
shows a polyp arising from a bridging portion of stolon. Polyps are present in many stages from moderately expanded to
completely retracted (Fig. 1De,r). Their base can vary from balloon-like to cylindrical, and is generally translucent
revealing the insertions of the mesenteries in the wall of the gastric cavity as well as any retracted parts of the polyp.
Polyp size varies considerably; the larger of the nearly retracted ones may have a cylindrical base in the vicinity of 3.8
mm tall and 1.3 mm in diameter.
The oral aspect of a polyp is shown in Fig. 1E. Larger polyps can have tentacles in the vicinity of 1.6 mm long and
0.8 mm across the medial zone. There is a single row of plump pinnules along each edge of a tentacle; the common count
is 12 per row, but it can be up to 15. Bifurcated or partially bifurcated pinnules are not uncommon.
Stolons vary in thickness from about 0.2–0.4 mm. Some parallel portions of stolons appear to have fused side to
side, but there are no membranous structures. All stolons and bases of polyps are covered with a thin cuticle.
The holotype colony is completely devoid of sclerites. The bright specks resembling xeniid sclerites, visible in the
polyp shown in Fig. 1E and those in Fig. 2B–E, are actually zooxanthellae.
Figure 2 shows live examples of Phenganax parrini, n. g., n. sp., in Daniel Knop’s aquarium from where the
holotype was selected. It illustrates polyps expanded and also in various stages of retraction; the wrinkled cuticle
covering a polyp base; and just how dense colonies can become in a man-made environment.
Paratype NTM C105598 is a colony fragment holding together a 20 mm long cluster of calcareous granules. Paratype
NTM C015599 is a colony fragment on a piece of calcareous material 19 x 10 x 7 mm.
The colour of all preserved colonies is pale grey. Live colonies (Fig. 2) have a pale oral disc. The species has been
observed at various locations in Indonesia, including Kotok Island and Raja Ampat, as well as in the Philippines, where
it can be found in well-spaced groups of 20–30 polyps in dimly lit, sheltered locations below 10 m, commonly associated
with Knopia octocontacanalis Alderslade & McFadden, 2007 and Clavularia spp. (Daniel Knop, pers. com.).
Etymology: named for Austin Parrin, for his extensive laboratory work involving this species.
Aquarium notes: (Neil Blackstone, Austin Parrin & Daniel Knop, pers. com.): The species has an extraordinary
ability to grow under almost any type of lighting from strong metal halide lights (250 watt) to dim fluorescent lamps.
Under strong lighting some tentacles, virtually always three per polyp, generally show a bluish fluorescence. These
darker tentacles can be seen in Fig. 2A, and to a lesser extent in Fig. 2B. Over time, from when first placed in an
aquarium, colonies become slightly more robust with less feathery-looking tentacles, and develop a considerable
increase in polyp density (Fig. 2A). The species prefers low light regions with moderate flow, where the stolons may
become more ribbon-like, and can only survive above 25°C.
Discussion: The small number of morphological features, and poor state of much of the literature, makes it difficult
to establish if any previously described species are congeners. Nevertheless, we think candidates for possible inclusion in
Phenganax n. g., along with their distinguishing characters, are as follows.
—Clavularia reptans Hickson, 1894, Sulawesi, described as having polyp-carrying stolons that bridge coral substrate
gaps, no sclerites, polyps 2 mm diameter when retracted, 7–10 mm expanded, and tentacles “with numerous densely
packed pinnules” (see Hickson’s pl. XLVII). Zooxanthellae are not mentioned. Depth 9–36 m.
— Clavularia reptans sensu Thomson & Henderson (1906: 402), Zanzibar, is unlikely to be Hickson’s species, which he
said has tentacles “resembling” C. garciae that has 30 pinnules/row. However, the 12–15 pinnules/row that their material
has indicates it might be the same as Phenganax parrini, n. g., n. sp.
—Clavularia celebensis Hickson, 1894, Sulawesi, encrusts dead coral with narrow and wide stolons. Polyps up to 8 mm
tall, tentacles with “numerous densely crowded pinnulae”, and no sclerites. Zooxanthellae not mentioned, but the
tentacles are green and polyp body and stolons are brown. Recorded from 18 m depth.
—Clavularia pregnans Thomson & Henderson, 1906, Kenya, basal membrane and not stolons, polyps to 5 mm tall,
“pinnules occur all around the tentacles”, no sclerites, zooxanthellae present. No mention of retractility, but the polyps
are “sometimes marked by contraction-rings” and Thomson and Henderson’s (1906) Plate XXX fig. 3 shows polyps with
a distinctly differentiated basal region.
Acknowledgements: We are indebted to Neil Blackstone, Austin Parrin and Daniel Knop for trusting us with this
project (also to Daniel for his superb colour photographs used in Fig. 2), and especially to Oscar Ocaña, Fundación
Museo del Mar, Spain, for supplying samples of Cervera atlantica for DNA analysis. Molecular work was funded by the
Cnidarian Tree of Life project (NSF grants EF-0531570 to C. McFadden and EF-0531779 to P. Cartwright).

5. ALDERSLADE & MCFADDEN68 · Zootaxa 3104 © 2011 Magnolia Press
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