ZoologicalJournal ofthe Linnean Society, 65: 367-384. With 6 figures
April 1979
A reconsideration of the sipunculan taxa
Fisherana Stephen, Mitosiphon Fisher and
Apionsoma Sluiter
EDWARD B. CUTLER
Utica College of Syracuse University, Utica, New York 13502, U S .A.
Acceptedfor publication February 1978
The sipunculan taxon Fisheram Stephen, erected as a genus, is critically examined. Type material of
three of the four originally assigned species is reviewed and Colfing~~
warini is shown to be a junior
synonym of G. lobostoma. Colfingia saualoui is reduced to a junior synonym of G . capitata. The subgenus
Mitosiphon Fisher is considered in light of the recent discovery of the tentacular arrangement of G .
murinae and G . misakiam. The tentacles do not surround the mouth bur lie dorsal to it as in
Phascolosoma. Following an analysis of hook and papilla morphology, including scanning electron
microscopy, F i s b a n a and Milosiphon are combined into one subgenus of Golfingia and the senior
available name is applied: Apionsoma Sluiter. Keys to the species in this subgenus and to the
subgenera of Golfingio are included.
KEY WORDS: - Sipuncula - Fisheram - Mitosiphon - Apionsoma - taxonomy - Golfingiidae.
CONTENTS
. . . . . . . . . . . . . . . . . . . . . .
Introduction
Systematicsection
. . . . . . . . . . . . . . . . . . . . .
Mitosiphon species . . . . . . . . . . . . . . . . . . . .
Golfingiamurim
. . . . . . . . . . . . . . . . . . .
Golfingia muakiana
. . . . . . . . . . . . . . . . . . .
Golfingia recondita
. . . . . . . . . . . . . . . . . . .
Golfingia trichocephola
. . . . . . . . . . . . . . . . . .
Fisherana species
. . . . . . . . . . . . . . . . . . . .
Colfingia saualoui
. . . . . . . . . . . . . . . . . . .
Golfingia capitata
. . . . . . . . . . . . . . . . . . .
Golfingiapapillqera . . . . . . . . . . . . . . . . . . .
Golfingaa lobostoma
. . . . . . . . . . . . . . . . . . .
Golfingiawarini
. . . . . . . . . . . . . . . . . . . .
Discussion
. . . . . . . . . . . . . . . . . . . . . . .
Conclusions
. . . . . . . . . . . . . . . . . . . . . .
Key to Apionsuma species
. . . . . . . . . . . . . . . . . . .
Acknowledgements
. . . . . . . . . . . . . . . . . . . .
References
. . . . . . . . . . . . . . . . . . . . . . .
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38 I
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INTRODUCTION
The genus Fisherana was first erected in 1964 in a short paper by A. C. Stephen.
It was subsequently included in Stephen 8c Edmonds’s 1972 monograph with this
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@ 1979 The Lirinean Society of London
E. B. CUTLER
368
definition: “Small species with trunk spindle to subcylindrical in shape. Hooks
on introvert with structure and shape like those of the genus Phascolosoma.
Papillae dome-like to conical in shape, often capped with a small protuberance,
and usually most densely packed at the anterior and posterior extremities of the
trunk as in Phascolosoma. Longitudinal musculature of the body wall continuous
as in Golfingza. One or two pairs of retractor muscles. Tentacles in some species
arranged in a crescent or near circle which lies dorsal to the mouth as in
Phascolosoma (the arrangement of the tentacles of the type species is not known)”
(Stephen & Edmonds, 1972).
Fisherana, type-species Phascolosoma papillijierum Keferstein, was erected to
include a few species which seemed intermediate between the genera GoEfingia
Lankester and Phascolosoma Leuckart. In Stephen’s (1964) key he distinguished it
from Golfingia on the sole feature of hook complexity. Edmonds, who took on
the task of completing the monograph after Stephen’s death, stressed the
importance of the tentacular arrangement and on this ground placed the group
in the newly established family Phascolosomatidae.
Fisherana is further discussed by Murina ( 1974-a new species and a key to the
species-and 1975, in a discussion of the evolution and phylogeny within the
Sipuncula). In both papers Fisheranu is treated as a subgenus of Golfingia with
some phasocolosomatid features. I concur in the placement of this taxon in the
Golfingiidae.
The subgenus Mitosiphon, erected in 1950 by W. K. Fisher to include G. hespera
(Chamberlain) and G. misakiana (Ikeda), was defined as follows: “Retractors 4;
longitudinal muscle layer not divided into bundles; nephridia bilobed; spindle
muscle attached to posterior end of body; introvert hooks with an accessory
comb of spinelets at base.” In Cutler (19731, where G. murinae Cutler and G.
Table 1. Material upon which this analysis is based
A. Museum specimens
1. Golfingiu cupitutu-Gerould’s type from National Museum of Natural History, Washington, D.C.
2. Golfingiu hesperu-Chamberlain’s type from Museum of Comparative Zoology, Harvard University
3. Golfingia hespera-from California, identified by W. K. Fisher, from National Museum of Natural
History, Washington, D.C.
4. Go~ngialo~ostoma-Fischer’stypefromZoologischesMuseumUniversitAtHamburg
5. Golfrngia longirostris-identified by E. Wesenberg-Lund, from Universitetets Zoologiske Museum,
Copenhagen
6. Golfingia misakiam-from Australia, identified by Fischer, from Museum fur Naturkunde HumboldtUniversitAt zu Berlin
7. Golfingia papibjera (sic)-identified by Sluiter, from Institut Ockanographique, Monaco
8. ColJingia reconditum-Sluiter’s type (external only)from Institut Ockanographique, Monaco
9. Goljngia lenuissima-identified by E. Wesenberg-Lund
10. Colfingia trichocephala-Sluiter’s type from Institut OcCanographique, Monaco
I 1. Golfingia wnrini-Lanchester’s type from British Museum (Natural History), London
B. More recent collections
1. Golfingiucapitata from the northwestern Atlantic
2. Golfingiu misuhiana-384 from Madagascar and Mombassa
3. Golfingiamzsahiuna-from Tanzania (courtesy of P. K. B. Menon)
4. Golfingiumisakianu-from East Africa (courtesy of G. Murina)
5. GolJingiu trichocephala-from southeastern United States (Cutler, 1973)
6. Go@ngiatrichocephala-off Durban (Stephen& Cutler, 1969)
7 . Golfingia trichocephala-267 from Madagascar and Arabian Sea
8. GolfingiaIrichocephala-from Australia (courtesy of S . J. Edmonds)
9. Golfingia trichocephula-from Texas and Florida Gulf coasts
SIPUNCULAN TAXONOMY
369
trichocephala (Sluiter)were added to this subgenus, the diagnosis was modified/expanded as follows: “ Four retractors; nephridia either bilobed o r single lobed;
spindle muscle attached to posterior end of body; introvert hooks, if present,
possibly with accessory comb of spinelets at base; tentacles possibly reduced;
introvert longer than trunk. ”
In Cutler 8c Murina (1977) it was proposed that G. murinae should be moved to
Fisherana on the basis of its now known tentacular arrangement. G. recondita
(Sluiter)was also shifted into Mitosiphon but with some uncertainty as the type is
unavailable for inspection.
Apionsoma was erected as a genus in 1902 by Sluiter for his new species
trichocephala. This taxon was transferred into Golfingia by Wesenberg-Lund
(1959b)as a separate subgenus. Stephen & Edmonds (1972) subsequently placed
it in the subgenus Golfingia sensu stricto. Sluiter’s description had several
shortcomings. The type material was re-examined and redescribed by Cutler
(1973).
The analysis of a large number of specimens from several areas has provided
me with important new data relevant to these m a . Table 1 lists the material
analysed for this study. Reference collections of G. capitata (Gerould), G.
misakiana, and G. trichocephala have been deposited in the American Museum of
Natural History, New York.
SYSTEMATIC SECTION
Mitosiphon species
Golfingza murinae Cutler, 1969
When this species (and its two subspecies) was first described it was based on
animals with incompletely extended introverts. A reference was made to one
individual which seemed to show the phascolosomatid tentacle arrangement.
Subsequent material has produced several more specimens with completely
extended introverts and confirms the presence of tentacles dorsal to the mouth
(Fig. lA, B). Complex hooks and papillae are present. The suggestion made in
Figure 1. GoIfingia murinue. A. Whole animal (scale 1 mm). B. Tip of introvert with oesophagus
protruding through mouth ventral to tentacles (scale 1 mm).
22
370
E. B. CUTLER
Cutler 8c Murina (1977) to move this into Fisherana was an error for reasons
discussed later.
Gogngia mzsakzana (Ikeda, 1904)
Phascolosoma hespera Chamberlain, 1920 : 3 1 .
Golfingia hespera Fisher, 1952: 392-395, pl. 24, figs 1-3. Stephen & Edmonds,
1972: 113. Amor, 1975: 115-1 16.
The identity of Go&ngta misakiana has been one of the more difficult problems
confronting sipunculan biologists. There have been five species names in the
literature. Cutler (1967, 1973) discussed this problem and synonymized G.
longzrostris and G. tenuissima with G. trichocephala. He also proposed informally
that G. hespera might be a junior synonym of G. misakiana and concluded that G.
trichocephala and G. misakiana are very similar. Since then, the acquisition of
additional specimens has required a re-examination of this complex. From a
collection taken at Dar es Salaam, P. K. B. Menon was able to determine the true
tentacular arrangement of G. misakiana (personal communication). Menon’s
specimens show the phascolosomatid array of tentacles dorsal to the mouth
(Fig. 2). A large Indian Ocean collection (over 650 specimens) recently analysed
by Cutler 8c Cutler (1979) also contributed to our knowledge. Unfortunately
Ikeda’s types of G . misakiana cannot be located and no recent collections have
been made around the type locality in Japan.
The most recent published work on this species is by Amor (1975) in which she
concurs with Cutler (1973) on most points but still retains the two species G.
misakiana and G. hespera. The sole distinguishing feature she uses is the number of
denticles/spinelets on the base of the hook. She maintains that G. hespera has 5-9
spinelets but some have no spinelets, while G. misakiana has 1-5 spinelets but
some lack them. Amor also describes how the rows of hooks show
differences-most spinelets being on the most distal rows of hooks while
proximally the number of spinelets decreases to zero. This division of a
population, otherwise identical, so that those with five or more spinelets are one
species and those with five or less are another seems unnatural and arbitrary. The
hooks from Fischer’s (1927)Australian specimens of G. misakiana exhibit 4 , 5 , and
6 spinelets.
Several interesting points grew out of a study of hook morphology using the
Figure 2. Go&ngia misakiam. Tip of introvert with oesophagus protruding through mouth ventral to
tentacles (scale 0.5 mm).
SIPUNCULAN TAXONOMY
371
scanning electron microscope and stimulated the following hypothesis.
Considering the ontogeny of these structures and the introvert itself, it is
proposed that when very young, the introvert is devoid of hooks, but at some
point hooks begin to be produced near the growing tip. These early hooks are
scattered, not in rows or rings, and these early hooks do not have spinelets
(Fig. 3C). Only later are spinelets produced on the hooks, at first only a few, the
full complement not appearing until maturity. Also, the growth of any one hook
is a gradual process, growing out of the dermal tissue much the same way as a
fingernail. This would mean that the most distal ring of hooks is in the early
stages of growth and not yet fully erupted so that even if it may eventually have
seven or eight spinelets, there is a time when only two or three are visible (Fig.
3A,B). Some appropriate supportive evidence comes from a recent study of
radular teeth in opisthobranch gastropods by Bertsch ( 1976) wherein he
recommends that knowledge about variations should replace typological
thinking with modern systematics. He suggests, “The presence o r absence of a
certain feature, such as denticles, may indicate a second species or it may show
simply an ontogenetic stage.”
Figure 3. CdJrngia m’suhiam hooks (see text for interpretation) (scale lOpm). A. First three rows
behind tentacles showing hooks in different stages of development. B. Fully formed hooks from
about the tenth row. C. Hook from zone of scattered hooks proximal to rows,without spinelets.
E. B. CUTLER
572
Table 2. Comparisons of two similar species of Mitosiphon
G . misakiam
G . murinae
Habitat
Shallow water (<50 m),
tropical or subtropical,
sand
Deep water (>50 m),
cold, mud
Epidermis
Thin, transparent
Not usually thin or
transparent
Retractor
muscles
Two pairs, short, thin,
and equal in size and
distance from ventral
nerve cord
Two pairs, longer,
stout, of unequal size
and distance from
ventral nerve cord
Nephridia
Bilobed and both lobes
of equal length
One subspecies
unilobed, other with
secondary lobe less than
1/3 the main lobe size
Introvert
length
From 10 to 12 times the
trunk length
From 4 to 6 times
the trunk length
Amor (1975) also commented on G. murinae and Murina’s G. hespera. She
suggested (without corresponding with this author or comparing material) that
G. murinae is really G. hespera or G. misakiana. The distinctions, discussed at length
in Cutler (1969: 214; 1973: 142-143), are not just in the size and density of the
papillae as Amor states, but include trunk size and shape, introvert length,
nephridia, retractors, pigmentation, and habitat (see Table 2).
The Indian Ocean collections provided me with a large series ofworms from a
single population and after some initial confusion I was able to accept the fact
that G. misakiana and G. trichocephda do co-exist in the same community. How
their niches differ is still unclear but may have to do with their feeding mode.
These populations are discussed more fully in Cutler 8c Cutler (1978). I t is
concluded that G. hespera contains only larger, older individuals of G. misakiana,
with larger papillae and more spinelets on the hooks, and is therefore a junior
synonym.
Goljngia recondita (Sluiter, 1900)
The only two identified specimens of this form are on public display in the
Oceanographic Museum at Monaco. In 1970 I was able to view the specimens
but not to remove them from the bottle. Recent attempts to obtain them for
closer inspection were fruitless because they were permanently fixed to a glass
plate inside the jar for display purposes.
It is probable that the length of the introvert exceeds the trunk length. As the
introverts of Sluiter’s specimens were retracted, his statement about the tentacles
surrounding the mouth is open to question, as discussed elsewhere in this paper.
He says that a fully developed, posteriorly anchored spindle muscle is absent but
that the posterior end of the gut coil is attached to the body wall by a muscle
divided into rays that come together near the most posterior convolution. With
no specimen it is difficult to interpret this but I am treating this as a spindle
SIPUNCULAN TAXONOMY
313
muscle. The peculiar nephridial state (apparently only described from one worm)
of a unilobed right nephridium and a bilobed left nephridium is also impossible
to verify. Sluiter compares it to the condition in G. abnorme (Sluiter). This latter
species has been considered a junior synonym of Phascolosmapectinatum by Cutler
8c Murina (1977).When inspected by me, G. abnorme clearly showed longitudinal
muscle bands and in all ways (except one unilobed nephridium) was identical to
P. pectinatum.
I t is tempting to change the status of this species because of the unavailability
of the type (and only) material. For the time being that temptation shall be
resisted.
Golfingia trichocephala (Sluiter, 1902)
As noted earlier this species has been discussed at length in Cutler ( 1973) and
little more need be said. In size, shape, form, and habitat it closely resembles G.
misakiana but lacks the posterior papillae, hooks, and tentacles. Murina leaves
this species in its own monotypic subgenus Apionsomu (personal communication)
because it lacks the hooks and tentacles. It is my opinion that these differences
are outweighed by the remainder of the traits which unite it with the other species
in this complex.
Fisherana species
Golfingia savalovi Murina, 1974
This species was described in detail by Murina as a new form distinguished
from G. capitata on an erroneous interpretation of Gerould’s description. She
thought the distal region of the introvert, described as an orange head, was
unique in G. capitata. After comparison of the two forms it became evident that
they were the same and after subsequent exchange of specimens, Murina now
concurs in this. Therefore, G. savalovi is ajunior synonym of G. capitata.
A few comments on the four species originally assigned to Fisherana by Stephen
are in order. All but the first were originally placed by their describers in the
genus currently known as Golfingia.
Golfingia capitata (Gerould, 19 13)
Forty specimens identified by Gerould have been examined as well as several
dozen individuals from recent collections. This material was provided by four
different sources as shown in Table 3. Gerould’s records ranged in depth from
about 1220-3200 m along the eastern United States from latitude 3 8 O 29’ to 41°
53’ N. Taken together this clearly shows a slope inhabitating species, absent from
the shelf and abyssal depths.
The extreme variability in the density and size of the trunk papillae make
statements like, “Trunk . . . with conspicuous scattered papillae which are thickly
scattered over the posterior end” (Stephen 8c Edmonds, 1972: 331) rather
misleading. Many worms have small and few papillae. Stephen 8c Edmonds’s
(1972: 331) comments about the point of origin of the retractor muscles in the
posterior end omit Gerould’s elaboration ( 19 13 : 423-424) on the extreme
E. B.CUTLER
314
Table 3. Recent collections of Go&ngiu cupitutu
Source
Howard Sanders,
Woods Hole
Oceanographic
Institution
Latitude
Longitude
Depth
(m)
Date
spec.
58
202
38" 34' N
56' S
39" 47' N
72" 55'W
12" 15' E
70" 50' W
1925
1535
1600
7/IX/63
23/V/68
22/11/69
40
6
5
28" 21' N
39"31'N
28" 50'W
31"05'W
1009
650
10/IX/71
25/X/ll
2
39" 42' N
70° 45'W
1860
28/VIII/59
I
3 9 O 12"
71" 48'W
2116
15IXII73
2
209
R/V Charcot,
Paris Museum
Natural History
136
R. Wigley, NOAA,
NMFS, Woods
Hole
Delaware
59-10
Tow 18
G . Rowe, Woods
Hole
No. of
Station
25
Knorr
1
312
Oceanographic
Institution
variability of this feature. The author concurs with Gerould's statement, viz:
"This species varies much in regard to the position of the points of attachment
of the retractor muscles to the body wall. Thus in one specimen both pairs were
attached near together near the middle of the trunk. In a small, young specimen
the ventral retractors have the usual attachment near the posterior end of the
body, whereas the slender dorsal muscles are joined to the body wall much
further forward than in the individual which I have figured (fig. 141, and
underneath the nephridia. In general, in a few specimens which I have dissected,
the position of the attachment of the dorsal retractors varies from about the
posterior end of the first third of the trunk backward to the posterior end of the
third quarter."
The epidermis is often very loose and fragile, rubbing off easily to give a very
different appearance, with the pale whitish underlying muscle layer and large
papillae the prevalent features (Fig. 4).
Unless the introvert is extended and the phascolosomatid arrangement of the
tentacles is visible, one can easily place this form in the subgenus Golfingzella
Stephen, and if one believes Wesenberg-Lund ( 1959a)about the spindle muscle,
it easily keys out to G. pudicu (Selenka). This problem of accurate determination
of tentacular arrangement will be returned to.
Golfingtapapillifera (Keferstein, 1865)
This was first described from a single specimen with a 9mm trunk (not
introvert as in Stephen & Edmonds, 1972: 322) and a 15mm introvert. The
arrangement of the 12 oval, leaf-like tentacles is neither commented on nor
illustrated and Stephen 8c Edmonds note (1972: 329): "How the tentacles are
ordered relative to the mouth is not known for the type F. papilltjera nor have we
been able to locate the type specimen. From a comparison with F. capitata and F.
wasini it seems possible that the tentacles of F. papillifera are arranged in the
typical Phuscolosoma-manner. If ever this is shown not to be so, the position of
SIPUNCULAN TAXONOMY
375
Figure 4. GoFngia capitata. Trunk papillae from specimen with sloughed off skin. A. General view of
posterior region (scale 0.2 mm). B. Two papillae (scale 0.1 mm). C. Tip of one papilla (scale
0.01 mm).
Fisheranu in the family Phascolosomatidae will be untenable.” It seems to me that
if the tentacles were visible to Keferstein, as they must have been for him to count
them, he would certainly have noted their arrangement if they were not typically
golfingiid. To assume otherwise is very risky.
In addition to Keferstein’s worm, there are only two other original records of
this species in the literature. Shipley (1902: 132) found “several specimens” in
coral and stone masses in the Laccadive Islands. His animals were longer
(30 mm) and all of the specimens had ruptured body walls with the retractors and
intestine protruding-not prime material. Attempts to locate his specimens at
Cambridge and London were not productive. The only other known record is
that of Sluiter (1912) from Cape Verde Islands. This single small worm ( 5 mm
trunk, 4 mm introvert) was obtained from the Monaco Museum and proved to
have not two but four well developed retractor muscles-clearly not Keferstein’s
species. Also, the longitudinal musculature while not obviously forming bands
showed upon close inspection a tendency towards splitting up; a normal
condition for a 5 mm Phcolosoma, possibly P . nigrescens Keferstein.
376
E. B. CUTLER
When Stephen (1964) first described Fisheranu he did not mention the tentacle
arrangement, which may account for his choosing this poorly known species for
the type. The appearance of the hook seems to have been important to Stephen,
but with no possibility of first hand verification, there is room for doubt.
Keferstein included it in the complex of species that are currently referred to as
Go@ngza and his comments on it did not suggest any thought that it was
significantly dissimilar from those such as G. pellucida Keferstein, which also has
hooks and large papillae.
Therefore, the species selected as the type for Fisheranu has no traceable
representatives in any museum. The only published descriptions are either not
verifiable (Shipley)or incorrect (Sluiter).Despite extensive collections in the area
of the type locality, Rice (1975a)does not report finding any representatives of
this species. This is hardly a firm foundation for a genus. One could make an
argument for placing this species in the subgenus Siphonoides Murina.
Goljingia lobostoma (Fischer, 1895)
This species has been recorded twice, the second only a note of the occurrence
of a single worm from Madagascar with no description other than a figure of its
hook. Recent collections of several hundred sipunculans from Madagascar
(Cutler 8c Cutler, 1979) failed to produce any representatives of this taxon. The
abbreviated translation of Fischer’s description found in Stephen 8c Edmonds
(1972: 333) says the introvert is 1.5 mm long-it should read 1.5 cm. It also
omits the fact that the spindle muscle is attached posteriorly. The original
description of the tentacles is unclear but does not sound like that proposed as
typical for Fisheranu, i.e. dorsal to the mouth. Fischer’s statement (1895: 14) is:
“Die Tentakel scheinen bundelweise vereinigt zu sein, 8-10 kleinere und 2
grossere konnte ich bemerken.”
Goljingia wasini (Lanchester, 1905)
This species, from off East Africa, has not been recorded since the original
description over 70 years ago, despite numerous collections in the area. The
distinctions between this form and G. lobostoma found on adjacent Madagascar
are ill-defined. The location of the nephridiopores “just anterior to’’ or “just
posterior to” the anus as found in Stephen 8c Edmonds’s key ( 1972)to this group
is not a very significant distinction. G . lobostoma has a posterior spindle muscle,
while G . wasini has a fine fastening mesentery attaching the gut convolutions to
the posterior end of the trunk according to Stephen 8c Edmonds (1972). In their
key this translates into “spindle muscle absent” in G. wasini. However,
Lanchester’s own words are ( 1905: 33) “The intestine is held to the hind end of
the body by a fine muscle strand. . .”. When I examined Lanchester’s specimens
I had no doubt that it is a normal spindle muscle. The brown hooks matched the
published figures well and measure 35-50 pm high, the clear streak often a bit
narrower than that shown in fig. 40F of Stephen 8c Edmonds (1972: 330). The
trunk length of these worms ranges from 3-9mm. The large papillae are
restricted to the two ends of the trunk and the midregion is quite smooth. It is
conceiuable that these may simply be juvenile Phascolosoma in which the
longitudinal musculature is still in its early ontogenetic state, i.e., undivided and
continuous.
SIPUNCULAN TAXONOMY
311
Edmonds re-examined the type material and says that the tentacles lie dorsal
to the mouth. In the four specimens I examined none of the introverts were
extended so this could not be verified. A side by side comparison of hooks and
papillae of G. lobostoma and G. wasini showed no significant differences in size,
shape or appearance. Externally the animals show no differences. Internally the
on1 detectable distinction (acknowledging their poor condition) is the minor
dif? erence in anudnephridiopore placement.
Based on these observations it is concluded that these two “species”, neither
having been collected for a very long time, are synonymous under the older
name G. lobostoma.
DISCUSSION
One basic biological question which has not recently been addressed in the
sipunculan literature is: what is our concept of a genus? The biological or
population species concept has been touched on but no explicit consensus has
been reached among different workers. This is less of a problem now than it has
been, but it is not yet resolved, nor shall this be an attempt to do so.
Stephen’s ( 1964) short preliminary work provided no philosophical basis for
his decisions except that the previous arrangement was “inconsistent at several
points”. The problem he saw was the longitudinal musculature and the way it
had been used as a taxonomic character. He felt it should be weighted more
heavily than it had been, thereby requiring the splitting of Aspidosiphon Diesing
into two genera and elevating Phuscolopsis Fisher with its single species to generic
rank. He also created a new subgenus (Goljngiella), resurrected the all but
forgotten name of Themiste Gray for the familiar Dendrostomum Griibe, and
created the genus Fisheranu.
The striving for internal consistency within natural systems is an admirable
trait, but, as an example, the action on Themiste and Phascolopsis did not make any
friends for systematists in the larger community of biologists who fail to see the
necessity for such changes.
The reality and consistency of the AspidosiphonJParaspidosiphon division is very
doubtful as the body musculature is not always either continuous or divided into
distinct bundles (Cutler, 1973; Cutler 8c Cutler, 1979; Ditadi, 1975; Murina,
1975).While it may be a convenient, often dependable tool for identification, a
subgeneric ranking for this character seems more than adequate, which brings us
back to Fisheranu and the genus concept.
I t is generally acknowledged that the rank given a taxon above the species level
is a subjective matter. A look at the history of the Sipuncula over the last 100
years easily illustrates this (Stephen & Edmonds, 1972).A genus has been defined
variously but one standard version from Mayr, Linsley & Usinger (1953:48)is:
“A genus is a systematic category including one species or a group of species of
presumably common phylogenetic origin, which is separated from other similar
units by a decided gap.” The focal point here is the “decided gap”; this is also
the point where judgments vary. This task was easier when we had less
information and fewer specimens. As the number and size of collections increase
we gain a better idea of how much natural variation occurs within a group
(population, species or genus) due to size, age, environmental conditions or type
of anesthesia/preservativesused. This requires a constant re-evaluation of earlier
constructs as the gaps become less distinct.
918
E. B. CUTLER
The creation of a genus is more synthetic than analytic and usually involves
evaluating several characters, not single ones. Which characters we select for this
purpose is crucial. Blackwelder ( 1967 : 202-203) comments: “There is no
question that all characters to be used are chosen by the taxonomist for that
particular use. This is a personal decision, regardless of what basis he uses for his
choice. The choice is, therefore, highly subjective. The choosing of the characters
is one of the major functions of the taxonomist.’’ He goes on to discuss good and
bad characters: “A good character at any level is one which ‘works’, which
produces a useful distinction or grouping. This means that it is ( 1 ) readily
detectable, (2)clear-cut in its segregation of the group possessing it, (3)complete
in its uniting of the members of the group, and (4)evidently correlated with other
aspects of the life of this group, so that the grouping itself is useful in a variety of
situations.’’ Blackwelder also comments on how good characters should not be
influenced by environmental factors and then concludes that section saying
(1967: 204): “These can be identified only in practice, by trial and recognition of
failure.” I t is my contention that the groupings proposed by Stephen are poor
because the characters he uses are not significant. Let us review them for
Fisherana .
Stephen (1964) used two characters, the hooks and papillae which are
supposedly complex and like those found in Phascolosoma. In Stephen & Edmonds
(1972) a third character is added, the arrangement of the tentacles.
Looking first at hooks, the assumption seems to be that all members of the
genus Phascolosoma have hooks of complex internal structure and that on any
single worm all of the hooks exhibit this complexity. In fact, there are at least six
species of Phascolosoma which have been described as lacking hooks altogether.
Furthermore, in those bearing hooks, the internal complexity is correlated to size
(age) of the hooks. Often those rings most distal (most recently formed) are
smaller, less pigmented, and without the “typical” internal characteristics. This is
not peculiar to Sipuncula as Bertsch (1976: 120) points o u t for radular teeth in
opisthobranchs : “Newly formed teeth have a different morphology than fully
formed teeth. Young teeth are weaker, thinner, and more transparent. . . .” It is
possible to select from a typical Phascolosoma a number of hooks which look ve
golfingiid o r to find none at all. While it is true that hooks in most GoCfFngia loo
different from most Phuscolosoma hooks and those known for Fisheranu are closer
to the phascolosomatid morph, it is not in my judgment a clear, distinct, good
generic character. As Bertsch (1976: 121) points out, “The opisthobranch radula
has an important use in taxonomy but it must be treated as a biological entity
subject to variation and not as the product of a typological mind.”
The papillae can also be misused. The papillae of a single worm taken from
different body regions may vary considerably in structure. Even more variation is
shown in a population of different-sized worms (e.g. G. jiagr$?ra (Selenka) in
Cutler, 1973). Supposedly Fisheranu have PhmcoloJma-likepapillae, i.e., dome-like
or cone-shaped with chitinous platelets, generally more pronounced and
complex than in Goljingia. To examine this more closely the scanning electron
microscope was again used and Figs 4-6 show some of the results. Other species
within each “genus” show quite different shapes and sizes, Phascolosoma pacijicum
having among the largest in that group. My conclusion is that the papillae of
Fisheranu species are not clearly distinct from many GoCfngia. A distinct “gap” is
hard to demonstrate, therefore this is a poor character.
u
SIPUNCULAN TAXONOMY
379
Figure 5. Papillae from two specimens of Golfingta capitafa. A and B from G . Rowe’scollection with
“normal” skin; C and D from H . Sander’s collection with “loose” skin. Difference possibly due to
post mortem chemical environment or nature of microhabitat while alive (scale 0. I mm).
In the definition of Fishmanu, one finds this phrase: “Papillae . , . usually most
densely packed at the anterior and posterior extremities of the trunk as in
Phcolosoma.” In the many species of Golfingta which bear trunk papillae, the
same distribution pattern holds true. In other words, this character, while used
in Stephen 8c Edmonds (1972) to relate Fisheranu to Phascolosomu, can just as
legitimately be used to relate it to GoLjngia. In Blackwelder’s terms neither the
hooks nor papillae are clear-cut in segregating Fisheranu from Golfingia.
An analysis of these characters must include some reflection on an old and
debated biological principle of ontogeny recapitulating phylogeny. There is
general agreement that Golfingza represents the early, primitive generalized
morph (Murina, 1975; Stephen & Edmonds, 1972: 15-18). What one sees during
the ontogeny of Pharcofosoma hooks, papillae, and musculature is a much more
golfingiid (generalized) condition, prior to maturity. In mature Fisheranu, one
sees an intermediate situation-a step in the Phascolosoma direction, a part of a
Figure 6. Comparison of Go@zgia and fhcolosoma papillae. The lack of chitinous platelets on the
surface of' the Pharcolosoma species is noteworthy and not restricted to these two species. I t may be
that this technology obscures these or that they are artifacts of light microscopy. Papillae of
Phascolosuma do do not appear very dissimilar to those of Golfingia on the surface. Much variation in
size and shape could be found on a single worm. A, B. Golfingia pellucida (scale 0.05 mm). C , D.
Pharcolosoma scolops (scale0.1 mm). E. fharcolosomapacijicum (scale0.1 mm).
SIPUNCULAN TAXONOMY
38 1
divergent evolutionary process. This is consistent with Murina ( 1975) but does
not imply that Pharcolosma evolved from any extant Fisherana.
The tentacular arrangement added to the definition of Fisherana by Edmonds is
an improvement but it is troublesome for different reasons. Using this character
requires that the introvert be completely extended and in the more than twenty
thousand sipunculans I have studied, probably one or two per cent have met this
criterion. Secondly, even with tentacles showing, the task of precisely locating the
mouth is very difficult unless the esophagus happens to be protruding through it.
This is rare. The likelihood of misidentifying a worm for this reason is great. It is
of course true that the classification of a group and the process of identification
are, or ought to be, separate processes. A practical problem remains which
relates to one of Blackwelder’s points, i.e. it simply is not readily detectable. It is
unfortunate that when they established their families for this phylum, Stephen 8c
Edmonds (1972: 19) invested heavily in this often hidden character. Table4
shows what remains from the definition of Fisheranu.
Table 4. Characters used in definition of Fisheranu
Character
~~
Genus which it resembles
~~~~
~
~~
Golfingia and Phcolosoma
leaning towards Phcolosoma
Golfingia and Phaxolosoma
Go&ngia
Golfingia and Phcolosoma
uncertain or P h c o l o s m a
Golfingia
Trunk size and shape
Hook structureand shape
Papillae shape and distribution
Longitudinal musculature
Retractor muscles
Tentacle arrangement
Egg shape’
’ Character not used by Stephen & Edmonds (1972).
I have added an additional character to the list-egg shape. Most phylogeneticists assume that similarities in type of egg, cleavage patterns, mesoderm
development, etc. are more instructive than adult external form. Leaning heavily
on external characters which are more likely to vary in an adaptive fashion (for
tasks like food gathering) can be misleading (Cutler, 1975). Gerould (1913: 422)
points out that “the eggs [of G. capitatal are spherical, small, and transparent,
covered with a yolk membrane pierced with distinct pore canals.” Rice (1975b:
152) tells us that “Although eggs of most sipunculans are spherical . . . those of
the genus Phascolosoma are characteristically flattened ellipsoids, frequently with
depressed apices.” These quotes have been confirmed by my own observations
and I would, therefore, suggest that this is a strong argument against a close
relationship between Fijherana and Phascolosoma.
CONCLUSIONS
In reviewing the evidence from gross morphology, light and scanning electron
microscopy on all of the material listed in Table 1, I conclude that the species
discussed herein are related and should be grouped together but d o not merit
generic rank. Rather, the taxon Fisheranu might be viewed as a subgenus of
GolJingia, acknowledging that it probably represents an offshoot of the main
branch in the direction of Phcolosoma.
E. B. CUTLER
382
Keturning to the Mitosiphon species: if we interpret the latest diagnosis of
Fisherana in one way it would behove us to move G. misakiana and G. murinae into
it as we now know them to have the phascolosomatid tentacle arrangement. This
was my first inclination, as evidenced in Cutler 8c Murina (1977). This would
leave only G. trichocephala and G. recondita in Mitosiphon. However, as G. hespera
(now G. misakiana) is the type for Mitosiphon, additional problems arise, i.e.
Mitosiphon would have seniority over Fisherana. Alternatively, the two groups of
species could remain separate if we simply modified the concept of Mitosiphon to
include its “proper” tentacle arrangement. After reconsidering the grouped
characters, this second alternative seemed logical and rational.
However, at this point two problems remain. These.two groupings are not very
distinct on paper and the argument for keeping them separate appears weak.
There is also the fact that Murina (1975) retains Apionsoma as a monotypic
subgenus. After some helpful correspondence with P. E. Gibbs, the most sensible
solution seems to be to place all of these species into a single subgenus and
apply the senior available name, which is Apionsoma. Those differences we might
have used for separating the taxa can now be used for constructing a key to the
species (below). There remains as much internal unity as within most other
subgenera. A problem with this idea is that the original concept bears little
resemblance to this revised version and as trichocephala now becomes the typespecies, it is externally the least “typical” of the group (i.e., lacking hooks,
tentacles, and papillae). But we now have some type material available for study.
There is reason to move in this direction as a solution to a perplexing and
troublesome situation. The revised subgeneric diagnosis proposed is :
Goljngia (Apionsoma) Sluiter, 1902 sensu Cutler
Two pairs of retractor muscles (except G. papillfera, which cannot be verified);
spindle muscle attached to posterior end of trunk; nephridia single or bilobed;
introvert hooks usually present; tentacles, where known, arranged in crescent or
near circle dorsal to mouth; introvert of varying lengths; papillae, when present,
most obvious at posterior end of trunk and often dome-like or conical. Includes
G. capitata, G. lobostoma (=G. wasini), G. misakiana (=G. hespera), G. murinae. G.
papillifera, G. recondita, and G. trichocephala (type-species).
Table 5 , showing some of the diagnostic characters of the six Goljzngia
subgenera, can serve as a key to the groups. It is noted there that Phascoloides
Table 5. Diagnostic table for Goljngia subgenera
Contractile
vessel villi
Number of
retractors
Posterior
spindle
muscle
Tentacles,
if present
Thysanocardia
present
2
absent
around mouth
Siphanoides
absent
2
present
around mouth
Nephcrroma
(Phascoloides)
absent
2
absent
around mouth
Golfingia
absent
4
absent
around mouth
Golfingiella
absent
4
present
around mouth
Apionsoma
absent
4
present
dorsal to mouth
(1 with 2)
SIPUNCULAN TAXONOMY
383
should now be replaced by Nephasoma Pergament. Informal consensus now
suggests that to retain Phuscoloides as suggested in Cutler & Murina (1976) would
be a violation of the International Code.
KEY TO Al'IdNSOMA SPECIES
1A. Introvert shorter than trunk; hooks without accessory comb of
spineletsatbase
. . . . . . . . . . . . . . . .
2
1B. Introvert equal to or longer than trunk; hooks, when present, with
. . . . . . . . . . 4
2A. Two retractor muscles . . . . . . . . . . . G . papillfera
2B. Fourretractormuscles . . . . . . . . . . . . . . 3
3A. Ventral retractor muscles arise in posterior half of trunk
. . G . capitata
accessory comb of spinelets at base
3B. Ventral retractor muscles arise in middle or anterior part of trunk
. . . . . . .
. . . . . . . . . . G.lobostoma
4A. Papillae, hooks, tentacles absent
. . . . . . . . G . trichocephala
4B. Papillae, hooks, tentacles present . . . . . . . . . . . 5
5A. Introvert more than 9 times trunk length; body wall thin, transparent, with small papillae
. . . . . . . . . .
G . misakiana
5B. Introvert less than 7 times trunk length; body wall thick, opaque,
with large papillae
. . . . . . . . . . . . .
G . murinae
ACKNOWLEDGEMENTS
The completion of this work was dependent on the co-operation of those
institutions listed in Table 1 for the loan of pertinent specimens. I am also
indebted to G. Murina, Sevastopol; P. K. B. Menon, Dar-es-Salaam; and S. J.
Edmonds, Adelaide, for the loan of specimens and for dialogues on this
problem. Dr Murina and Dr P. E. Gibbs, Plymouth, have read an earlier version
of the manuscript and offered helpful comments.
Dr Anthony Checchi, Utica College, provided valuable assistance with the
scanning electron microscopy which was performed in the Biology Department,
University of Massachusetts, Boston. Mr Henry Iwanicki made the drawings. Ms
Norma Cutler provided many forms of assistance throughout this project.
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