/. MolL Stud. (1997), 63,311-325
© The Malacological Society of London 1997
CLADISTIC ANALYSIS OF THE OCTOPODS BASED ON
ANATOMICAL CHARACTERS
JANET R. VOIGHT
Department of Zoology, Field Museum of Natural History, Roosevelt Road at Lake Shore Drive, Chicago,
IL 60605, USA
names derive from the two rows of cirri that
parallel the suckers on each of their arms, also
Parsimony analysis of 29 finned andfinlessoctopod present are fins and an internal shell or fin
taxa considered 66 anatomical and morphological
support that spans the breadth of the mantle.
characters to discover synapomorphies that unite
These characters appear to be primitive, as they
monophyletic groups. The resultant cladogram (177
are shared in some form with squids and cuttleequally parsimonious trees at 191 steps, CI 0.429)
fishes, the other coleoid cephalopods. Finless
resolved all relationships except those among the 16
octopuses have been assigned to the suborder
exemplars of the Octopodidae included and those
among Tremoctopus, Ocythoe and Argonauta. Boot- Incirrata, the Order Octopoda Leach, 1817 of
strap values of over 90% support the monophyly of
Young (1989); this group lacks the above
the finned and finless octopods, relationships among
characters. Despite the rarity of hard parts in
the finned octopods, the bolitaenids and the monooctopod specimens, classifications have relied
phyly of Haliphron, Tremoctopus, Ocythoe and Argo- heavily on characters such as thefinsupport of
nauta; bootstrap values for other nodes range from 57 curates and the radula of incirrates. To avoid
to 79%. Among finned octopods, specimens repreany confusion caused by the different applicasenting Grimpoteuthis are basal, as Voss (1988a)
suggested. Specimens of Opisthoteuthis represent a tions of the term Octopoda, here I refer to
divisions within the octopods as cirrates and
distinct lineage, and are sister taxon, in this analysis,
of Cirroteuthis (although specimens of Stauroteuthis incirrates.
could not be included). New definitions of the genera
Attempts to increase our understanding of
Opisthoteuthis and Grimpoteuthis are provided to
octopod evolution have been perceived as
reflect their separate evolutionary histories rather
limited by the few fossil specimens available
than their overt morphological similarity. Among
(Robson, 1932; Roger, 1944; Voss, 1988a);
finless octopods, bolitaenids are basal. The monoperhaps a more significant limit is imposed by
phyletic Octopodidae is the sister taxon to the clade
the rarity of specimens of extant taxa. As many
containing the -sister taxa Vitreledonella and
Amphitretus, and Haliphron, Tremoctopus, Ocythoe octopod taxa are known only from depths
and Argonauta. The Ctenoglossa and Heteroglossa,
greater than 400 m, including most cirrates, five
families grouped by shared radular dentition, are
meso-pelagic incirrate families and seven
diphyletic and paraphyletic, respectively. The cladoctopodid genera (Voss, 1988b), specimens are
istic relationships demonstrate that both the Vitrelefew. Mature (spermatophore-carrying) males
donellidae and Idioctopodidae are junior synonyms
of meso-pelagic groups remain unknown. As
of the Amphitretidae; despite conspicuous morphspecimens of cirrates have become more availological differences separating these taxa, they share
able over the last century, their classification
a recent evolutionary history.
has been revised (Grimpe, 1916, cited by
Robson, 1932; Voss, 1988a). Despite increased
collections of meso-pelagic incirrates (Thore,
1949), Naef's (1923) classification of the group
INTRODUCTION
has remained unaltered.
Gassification of the octopods, cosmopolitan
This cladistic analysis of the octopods identimarine predators with eight arms and muscular fies monophyletic groups using anatomical
suckers, is based largely on single characters. characters that, when possible, reflect the
The bentho-pelagic finned octopods have been acquisition of new features rather than the loss
assigned to the sub-order Cirrata, and to the or reduction of plesiomorphies. The resultant
Order Cirroctopoda by Young (1989); the topology reveals hypotheses of relationships
ABSTRACT
JR. VOIGHT
312
that reflect our current knowledge. As new
information becomes available, this topology
should be re-examined to assess its stability.
for mid-water taxa are based on Thore (1949).
Hochberg et al (1992) provided additional
information, with additional references as
noted.
OUTGROUP TAXON
QRRATA: Octopods with paired fins, an internal fin
support, cirri, arm suckers in one row, mantle
aperture and radula variably reduced, no ink sac or
right oviduct.
Cirroteuthidae. Cirrates with thick, saddle-shaped fin
support, sepioid gills, long cirri, intermediate web,
elongate body, radula absent. Representative:
Cirroteuthis muelleri Eschricht, 1836.
Opisthoteuthidae. Cirrates with U- or V-shaped
fin support, half-orange gills, short cirri, simple
web, body bell- or disk-shaped, radula variable.
Representatives: Grimpoteuthis bathynectes Voss
& Pearcy, 1990; Grimpoteuthis sp. A; Opisthoteuthis agassizi VerriU, 1883; O. califomiana Berry,
1949.
INCIRRATA: Octopods without fins, fin support or
cirri. Both oviducts present, sucker arrangement
and presence of ink sac and esophageal crop
variable.
Alloposidae. Mid-water incirrates with tricuspid
rachidian teeth without seriation, complex, detachable hectocotylus, without apparent secondary
sexual dimorphism. Monotypic: Haliphron atlanticus Steenstmp, 1859 = Alloposus mollis Verrill,
1880, according to Willassen (1986). As the more
senior name has been virtually unused, Hochberg
et aL (1992) retained Alloposus; I follow Young's
(1995) use of Haliphron. Alloposidae, to my
knowledge, is the only family name that has been
applied to this group.
Amphitretidae. Mid-water incirrates in which the
rachidian and lateral teeth are multicuspid and
seriated (ctenoglossan radula), viscera rotated
cephalad, mantle aperture restricted to two lateral
openings, telescopic eyes oriented dorsally, one
sucker row. Representative: Amphitretus pelagicus
Hoyle, 1885.
Argonautidae. Epipelagic incirrates with tricuspid
rachidian teeth without seriation, complex, detachable hectocotylus, dwarf males, eggs brooded in
case produced by dorsal arms of females. Representative: Argonauta argo Linn6,1758.
Bolitaenidae. Mid-water incirrates with ctenoglossan
radula, one sucker row, wide mantle opening.
Representatives: Eledonella pygmaea Verrill, 1884;
Eledonella sp. A;Japetella diaphana Hoyle, 1885.
Octopodidae. Benthic incirrates typically with multicuspid, seriated rachidian teeth (sometimes unicuspid or absent), simple lateral teeth, secondary
sexual dimorphism minimal, simple hectocotylus,
usually with ligula and calamus, arm sucker
arrangement and presence of crop and ink sac variable. Only a subset of the over 200 nominal species
and 25 genera that Hochberg et al. (1992) estimated
to have been assigned to the Octopodidae are
included here. The need to assess the monophyly
of the group conflicts with the computational difficulties imposed by the inclusion of a large number
The extant taxon, Vampyroteuthis infernalis
Chun 1903, has been recognized as the sister
group to the octopods based on characters that
are otherwise unique among coleoid
cephalopods. These presumed synapomorphies
include the dense concentration of ganglia in
the brain, the position of the superior buccal
lobe (Young, 1977), inner and outer statocyst
sacs separated by perilymph (Young, 1989), the
reduction of one of the five arm pairs, muscular
suckers without horny rings, the digestive duct
appendage (pancreas) being within, rather than
separate from, the digestive gland and the form
of the systematic heart (Pickford, 1939). Specimens of V. infernalis, however, document that
the group has had its own evolutionary history.
For example, these animals lack an ink sac, a
character present in all other coleoid cephalopods except cirrates and a comparatively few
benthic octopuses. Following Young (1964), I
consider this loss to be a derived state.
INGROUP TAXA
Included in the analysis were octopod taxa
representing as much of the group's known
diversity as possible. Specimens of the finned
genera Stauroteuthis, Chunioteuthis and Cirrothauma and of the incirrate genus Idioctopus,
however, could not be included. The available
specimens of these fragile deep-sea taxa were
too damaged to allow relevant characters to be
scored. Aldred, Nixon & Young's (1983) monographic treatment of specimens of Cirrothauma
murrayi Chun, 1913, Robson's (1924) detailed
description of Chunioteuthis gilchristi (Robson,
1924) and Taki's detailed (1963) report of
Idioctopus gracilipes Taki, 1962, and examination of a partial specimen of this species,
allowed post-hoc consideration of these taxa.
Possible misidentification of specimens Ebersbach (1915) referred to Stauroteuthis made his
account unreliable (Robson, 1932; Young,
1989).
Below, the octopod groups included in the
analysis are summarized. The specimens examined are listed in Appendix 1. The summary
diagnoses of the cirrates and deep-sea octopodids are based largely on Voss (1988a); those
CLADISTIC ANALYSIS OF THE OCTOPODA
of taxa. To balance these opposing constraints,
specimens representing genera that Toll (1991)
suggested merit formal recognition, and as many
representatives of deep-water genera as possible,
were included.
Bathypolypus Grimpe, 1921. Deep-sea octopodids
with two sucker rows, no ink sac or CTOp, papillose
skin, unicuspid rachidian teeth, reduced posterior
salivary glands, funnel organ W . Representative:
B. arcticus (Prosch, 1849).
Benthoctopus Grimpe, 1921. Deep-sea octopodids
with two sucker rows, no ink sac, crop with diverticulum, smooth skin, multicuspid rachidian teeth,
large posterior salivary glands, funnel organs W
(rarely W ) . Representative: B. hokkaidensis
(Berry, 1921).
Cistopus Gray, 1849. Octopodids with two sucker
rows, elongate mantles, constricted heads and
necks, water pouches on oral surface of each web
sector, small, poorly developed ligula. Representative: Cistopus sp.
Eledone Leach 1817. Octopodids with one sucker
row, ink sac, crop, multicuspid rachidian teeth,
large posterior salivary glands, funnel organ W,
hectocotylus lacks calamus, other male arms
heteromorphic at tip, Voight (1993a) adds:
branchial retractors fused medially on ventral
mantle, eggs fertilized in the ovary. Representative: E. cirrhosa (Lamarck, 1798).
Graneledone Joubin, 1918. Deep-sea octopodids with
a single sucker row, no ink sac, no crop diverticulum, skin with tubercles, radula homodont or
variable, few gill lamellae, small posterior salivary
glands, funnel organ W . Representatives: G.
pacifica Voss & Pearcy, 1990; G. antarctica Voss,
1976.
Hapalochlaena Robson, 1929. Octopodids with two
sucker rows, small size, fixed, characteristic iridescent blue markings on mantle and arms, few (4-9)
gill lamellae. Representative: H. lunulala (Quoy &
Gaimard, 1832).
Octopus (O). Lamarck, 1798. Octopodids with two
sucker rows, crop and ink sac, multicuspid seriated
rachidian teeth, wide mantle aperture, variable
shape, size, gill lamellae number, color, ligula
shape. Representative: O. (O.) bimaculatus
(Verrill, 1883).
Octopus (Callistoctopus) (Taki, 1964). Following
Norman (1992), octopodids with two sucker rows,
elongate arms, first arms longest, ligula deeply
grooved, red and white color, multicuspid seriated
rachidian teeth, many (10-14) gill lamellae. Representative: O. (C.) omatus Gould, 1852.
Octopus (Macrotritopus) Grimpe, 1922. Octopodids
with two sucker rows, elongate mantles and arms,
third arms the longest with the most suckers
in planktonic young. Representative: O. (M.) horridus (Orbigny, 1826).
Pareledone Robson, 1932. Following Lu & Stranks
(1994): Octopodids with one sucker row, ink sac,
crop, multicuspid rachidian teeth, gill lamellae
number 6-9, hectocolytus with ligula and calamus,
large posterior salivary glands, funnel organ W or
313
W-shaped. Circum-Antarctic. Representative: P.
charcoti (Joubin, 1905).
Pteroctopus Fischer, 1882. Octopodids with two
sucker rows, gelatinous skin with low, dense
tubercles, hectocotylus on left, web noted to be
deep. Representative: P. tetracirrhus (delle Chiaje,
1830).
Robsonella Adam, 1938. Octopodids with two sucker
rows, stout, bulbous ligula, penis with long primary
and secondary diverticula. Representative: R.
fontaniana (OTbigny, 1835).
Scaeurgus Troschel, 1857. Octopodids with two
sucker rows, skin with dense, rounded papillae,
hectocotylus on left, ligula long, swollen. Representative: S. unicirrhus (d'Orbigny, 1840).
Tetracheledone Voss, 1955. Octopodids with one
sucker row, ink sac, crop, skin with tubercles, unicuspid rachidian teeth, large posterior salivary
glands, funnel organ four-parted. Monotypic: T.
spinicirris Voss, 1955.
Velodona Chun, 1915. Octopodids with one sucker
row, crop, ink sac, large posterior salivary glands,
dramatic web extensions on ventral arm surface,
skin with papillae, unicuspid rachidian teeth,
funnel organ VV. Representative: V. togata Chun,
1915.
undescribed gen. & sp. (C.F.E. Roper, F.G.
Hochberg, B.A. Seibel in prep.). Octopodids with
elongate mantle, crop and stylets, ink sac absent,
skin without apparent functional chromatophore
organs, known only from East Pacific Rise
hydrothermal vents.
Ocythoidae. Epipelagic incirrates with tricuspid
rachidian teeth without seriation, complex, detachable hectocotylus, dwarf males, ventral mantle
surface of females tuberculate, one pair cephalic
water pores. Monotypic Ocythoe tuberculata
Rafinesque, 1814.
Tremoctopodidae. Pelagic incirrates with tricuspid
rachidian teeth without seriation, complex, detachable hectocotylus, dwarf males, two pairs of
cephalic water pores; in adult females, web sectors
A and B extensive, dorsal arms I often truncated.
Representative: Tremoctopus violaceus della
Chiaje, 1830.
Vitreledonellidae. Mid-water incirrates with multicuspid, seriated rachidian teeth, simple lateral
teeth, viscera rotated cephalad, wide mantle opening. Monotypic: VitreledonellarichardiJoubin, 1918.
Cirrate genera have been assigned to families
based on the shapes of the internal shell and
gills, and on the structure of the interbrachial
web (Robson, 1932; Voss, 1988a). Taxonomic
treatments of incirrates have been based on the
number of arm sucker rows (Joubin, 1918;
Voss, 1988a), radular dentition (Thore, 1949),
and habitat (Young, 1989; 1995). Naef (1923)
identified Haliphron, Ocythoe, Tremoctopus
and Argonauta as sharing a common ancestor
based on similarities in form, development and
position of the hectocotylus, strong sexual size
J.R. VOIGHT
314
dimorphism (known in three of the four) and
the tricuspid rachidian teeth, characters that
are unique among octopods.
CHARACTERS ANALYZED
Despite the recognized need for comparative
anatomical studies of cephalopods (Naef, 1923;
Voss, 1977; Vecchione, 1994), few anatomical
accounts of even a single taxon have been produced since the 1920's (Young, 1964; Roper,
1966; Thomas, 1977; Aldred et al., 1983). The
taxonomic tradition, rather, has become one of
removing the digestive and reproductive organs
from the mantle, stripping them of blood
vessels, nerves and muscles, then illustrating
them in species descriptions. This procedure
so limits the characters available that too few
can be recovered to reconstruct relationships
within the Octopodidae (Voight, 1993b).
Examining organs in situ, as was done here,
allows characters based on arterial branching
patterns and the anatomy of muscles which
extend between organs within the mantle cavity
to be considered. After making a mid-ventral
incision in the mantle wall, severing the funnel
depressors and the head retractor muscles
bilaterally near their insertion on the inner
mantle wall (and any additional muscles that
insert medially on the wall), flexing the mantle
over the head exposes the viscera on the dorsal
surface of the digestive gland for examination.
Characters and character states on which this
analysis are based are listed below, grouped by
organ system. Sixteen characters pertain to
overall morphology, 15 relate to reproduction,
13 to the digestive system, six to respiration,
one to the ink sac, eight to the circulatory
system, four to the stellate ganglion and three
to muscles inside the mantle. The eight characters that represent losses or reductions are indicated, as are the eleven multistate characters
that were always analyzed unordered. Four
additional multistate characters were analyzed
ordered. Character states unique to a single
taxon were excluded from the matrix.
1. How many pairs offinsare present during some
stage of the life cycle? Two = O, only one = 1;
none = 2. Loss.
2. Is a gladius, fin support or pair of stylets present
in the dorsal mantle musculature? Gladius-like
dorsal shield = 0; fin support within posterior
mantle = 1; stylets in lateral mantle musculature
= 2; none detectable = 3. UNORDERED; LOSS.
Contrary to earlier reports, gelatinous masses,
scored here as stylets, are present in the dorsolateral mantle of specimens of Haliphron. The
3.
4.
5.
6.
7.
8.
9.
10.
similarity of the stylets' consistency to that of
the musculature may have contributed to their
having been overlooked. Contrary to the report
of Lu & Stranks (1994), stylets are present in at
least some members of Pareledone.
Do specimens have a gelatinous (amorphous)
coating? no = 0; yes, during at least some stage of
the life cycle = 1. Small specimens of Japetella
have a gelatinous coat (Thore, 1949).
Are ventral cephalic water pores present in
adults? no = 0; yes = 1.
Are muscular septa present in dorsal arm musculature? no = 0; yes = 1. Young (1977: Fig. 24) and
Nixon & Dilly (1977: Fig. 64) illustrate these
septa in Japetella.
Do cirri occur lateral to the suckers on all arms?
yes = O, no = 1. Loss.
Do the arm suckers occur from immediately
adjacent to the buccal mass to the arm tip? no =
0;yes = 1.
Do all arms (excluding the hectocotylus) carry
the same number of suckers? yes = 0; no, first
arms have more suckers = 1; no, third and fourth
arms have more suckers = 2. UNORDERED. AS
arms are likely derived from a common primordial bud, they are considered to be directly
homologous; differences among them are
derived.
Does the web extend to near the tips of all arms?
yes = 0; no = 1.
Does the web extend symmetrically about
arm axis? yes = 0, no, asymmetrically, deeper on
ventral arm = 1; no, dorsal sectors dramatically
extended = 2. UNORDERED.
11. Does afleshynodule, orfinger-likeprocess, unite
the ventral surface of arms with the distal border
of web? no = 0; yes = 1. This character refers to
the thickening noted on the ventral cirrate arm
by, e.g. Voss & Pearcy (1990) among many
others, it is also present in specimens of
Velodona.
12. Does skin extend between sucker acetabula on
lateral surface of arm? no = 0; yes = 1.
13. How many suckers are on the arms with the most
suckers? under 60 = 0; over 75 = 1.
14. Does a pair of extrinsic sucker muscles extend
between the sphincters of serial suckers? no = 0;
yes = 1. These muscles were apparently first
reported in Benthoctopus levis (Hoyle, 1885) by
Joubin (1900).
15. Is the skin texture permanently rough, apparently
independent of dermal muscles? no = 0; yes = 1.
16. How many arms are present? 10 = 0; 8 = 1. Loss.
17. What is position of gonad relative to spiral
caecum? ventral = 0; dorsal = 1.
18. Do the sexes differ by more than 50% in body
size at maturity? no = 0; yes, females much larger
than males = 1.
19. Are posterior salivary glands larger in mature
males than in females? no = 0; yes = 1 (Voight,
1995).
20. Are both oviducts present? yes = 0; no, right
oviduct absent = 1. Loss.
CLADISTIC ANALYSIS OF THE OCTOPODA
21. How do the right and left oviducts diverge from
their common origin? at a 90° angle = 0; an acute
angle = 1.
22. Is a cervix, sensu Peterson (1959), present at the
junction of the oviductal gland and the distal
oviduct? no = 0, yes = 1.
23. Does the oviductal gland contain radially
arranged spermathecae? no = 0; yes = 1.
24. What is the appearance of penis? With weak
diverticulum at an oblique angle = O, with accessory glands closely associated = 1; with bulbous
diverticulum = 2. UNORDERED. Although
Thomas (1977) termed the terminus of the internal male reproductive system of Tremoctopus,
Needham's Sac, I follow Marchand (1907) in
referring to this structure as the diverticulum. As
few males of Ocythoe, Tremoctopus and Argonauta were available, scoring of male reproductive characters for these taxa were supplemented
by data from Naef (1923) and Thomas (1977).
25. Does a muscle extend from penis to ventral
mantle septum? no = O, yes = 1.
26. Is one of the third arms of males modified to
form a hectocotylus? no = 0; yes = 1. Use of the
term hectocotylus (an arm modified apparently
to transfer spermatophores) does not imply
homology between the octopod arm and that
of teuthoids. Differences in the affected arm and
the type of modifications (see review by Voss &
Voss, 1983) suggest convergence between the
groups.
27. Are any suckers on males arms so grossly
enlarged that their function may be impaired? no
= 0; yes = 1. This excludes the enlarged suckers
of octopodids; despite their enlargement, they
appear to function as do other suckers.
28. Is the hectocotylus wholly contained in a pouch in
the web? no = 0; yes = 1.
29. Is the suckerless tip of hectocotylus (ligula) very
long and conic? no = 0; yes = 1.
30. Does the hectocotylus have lateral fringe near its
base? no = 0; yes = 1.
31. Is calamus present between the distal-most
sucker of hectocotylus and the arm tip? no = 0;
yes, present as a small structure on the oral arm
surface = 1; yes, present as a large structure on
lateral arm surface = 2. Size here is estimated
relative to ligula length. The lateral position is
considered derived as homology with an arm
sucker is hypothesized.
32. What is the dentition of the rachidian teeth? unicuspid = 0; multicuspid = 1; tricuspid = 2.
UNORDERED. States of this character were coded
for cirrates based on reports by Voss & Pearcy
(1990), for Robsonella on reports of Robson
(1929) and Mangold and Portmann (1989) and
for Bathypolypus on those of Verrill (1880) (as
O. bairdii), Robson (1932) and Mangold &
Portmann (1989), all of which agreed.
33. What is the dentition of first and second lateral
teeth? simple = 0; multicuspid = 1.
34. What is the posterior salivary gland texture?
tubes very coarse = 0; tubes very fine = 1.
315
35. Where is (are) the posterior salivary gland(s)?
cephalad of digestive gland = 0; absent from the
mantle cavity = 1; dorsal to esophagus = 2.
UNORDERED; LOSS. Hochberg et aL (1992) report
the posterior salivary glands to be absent in
incirrate octopods other than octopodids and
Amphitrelus, my observations conflict with this
statement.
36. What is the configuration of the posterior salivary
gland? single = 0; paired = 1.
37. Do posterior salivary gland ducts enter the
esophageal crop directly? no = 0; yes = 1.
38. What is the form of esophageal crop? subtle
dilation without apparent sphincter = 0; diverticulum broadly open to esophagus = 1; diverticulum narrowly open to esophagus = 2.
UNORDERED.
39. How is the esophageal crop positioned relative to
digestive gland? dorsal = 0; cephalad = 1.
40. How is the caecum positioned relative to the
stomach? lateral = 0; ventral = 1; dorsal = 2.
UNORDERED.
41. Is the caecum separate from digestive gland?
yes = 0; no, contained within the membrane
surrounding the digestive gland = 1.
42. What is the degree of coiling in the caecum? only
a partial or one complete spiral = 0; more than
one complete spiral = 1.
43. At its entry to the mantle septum, what is the
position of the rectum? sagittal = 0; para-sagittal
—^
44. Does the digestive gland have more than one
lobe? no = 0; yes = 1.
45. Does efferent branchial vessel divide the gill
along its midline? yes = 0; no, gill composed of
discrete, radial sections, termed 'half-orange'
type by Robson (1932) = 1.
46. Is mantle-funnel locking apparatus strongly
developed with complex, folded mantle element?
no = 0; yes = 1.
47. How many lamellae are in the outer demibranch
of the gill (counting minute terminal lamella)?
twelve or more = 0; ten or fewer = 1. Loss.
48. What is funnel organ shape? V = 0; W = 1; W =
2. UNORDERED.
49. Is the mantle aperture broadly open? yes = 0; no,
tightly contracted around funnel (at least in
preservation) = 1; no, fused to funnel medially,
open laterally = . (autapomorphy of Amphitretus, coded as missing). Only extreme closure
was scored as 1 here; the variable closure of
the mantle cavity Robson (1929) discussed and
classified among octopodids was scored as 0.
50. Is the branchial gland attached to mantle wall for
the length of the gill? no = 0; yes = 1.
51. Is the ink sac present? yes = 0; no = 1. Loss.
52. How is the systematic heart positioned relative to
the viscera? dorsal (including on the posterior tip
of the viscera) = 0; ventral = 1.
53. Is dorsal aorta (the main artery that leaves the
systematic heart to run dorsally across the digestive gland toward the brain, sometimes termed
cephalic artery in cirrates) constricted cephalad
J.R. VOIGHT
316
54.
55.
56.
57.
58.
of its origin at the systematic heart? no = O, yes =
1. Illustrated by Aldred el al (1983: Fig. 13).
Where does the pallial artery (the artery that
carries blood from the dorsal aorta to the dorsolateral mantle wall, termed 'fin' artery in cirrates,
posterior mantle artery by Young (1964) in
Vampyroteuthis and dorsal artery by Chun (1915)
in a bolitaenid) originate relative to systematic
heart? within one heart length = 0; over two
heart lengths = 1.
Do the right and left pallial arteries branch from
the dorsal aorta separately? yes = 0; no, common
pallial artery present (regardless of its length) =
1. Polymorphic in Vitreledonella; dorsal chamber
of Aldred et al. (1983) scored as common pallial
artery.
Where does the left pallial artery branch? distant
to the artery's origin, lateral to viscera = 0; close
to its origin, dorsal to viscera = 1.
Where does the first branch of the dorsal aorta
flow? viscera = O,finsor mantle = 1.
What organs does the gastric artery (the artery
that minimally carries blood to the stomach)
serve? stomach and digestive gland = 0; stomach
only = 1; stomach, crop and digestive gland = 2.
UNORDERED.
59. How many arteries from the dorsal aorta feed the
esophageal crop? three or fewer = 0;fiveor six =
1; nine or more = 2.
60. What is the condition of the photosensitive
vesicle? absent from stellate ganglion = 0;
present in stellate ganglion as single vesicle = 1;
present in stellate ganglion as multiple vesicles =
2. State of this character in Vampyroteuthis coded
from Young (1972).
61. Does the stellate ganglion occur lateral to gill? no
= 0;yes = 1.
62. What is the orientation of nerves emerging from
the stellate ganglion? narrow band = 0; star-burst
emergence = 1.
63. How many large nerves emerge from the stellate
ganglion? comparatively few (6 or fewer) = 0;
many (over 9) = 1.
64. Does a muscle extend from the digestive gland to
the junction of esophagus and stomach to form a
muscular sling that holds the dorsal aorta? no =
0;yes = 1.
65. Does a muscle extend from the hard part of the
stomach to the sheath over the digestive gland?
no = fr.yes = 1.
66. Is a ventral mantle septum present? no = 0; yes,
restricted to the anterior part of the mantle = 1;
yes, extending over the length of the mantle, at
least as a strip of muscle = 2. UNORDERED.
ANALYSIS
The character matrix (Appendix 2) was examined to
ensure that every taxon differed from all others by at
least one character state and that no character state
was unique to a single taxon. This resulted in
members of genera that had identical character distributions, such as Graneledone and Eledonella, being
represented by a single taxonomic unit.
The analysis was conducted using the heuristic
search options in PAUP 3.1.1 (Swofford, 1993) to
attempt to discover the most parsimonious solution.
Twenty-five replicates using random stepwise addition of taxa were run to increase the probability that
all most parsimonious trees were discovered. Character state changes were optimized on the cladogram
with delayed transformation (deltran) optimization.
Under this optimization, character state changes that
can be interpreted as either convergences or reversals
in the same number of steps are attributed to convergence. Character state changes that have ambiguous
interpretations are discussed in the text. One hundred
replicates of bootstrapping with tree-bisectionreconnection branch-swapping and mulpars in effect
were performed to assess the stability of the tree
topology.
To assess whether characters that reflect loss or
reduction contribute as much information as do
characters of acquisition, or if they show more homoplasy than do positive characters, consistencies of the
characters identified above as losses are compared to
those of other characters.
RESULTS AND DISCUSSION
The strict consensus tree of the 177 equally
most parsimonious trees discovered at 191 steps
(Consistency Index = 0.429; Retention Index =
0.678) resolves all relationships except those
among thirteen of the sixteen exemplars of the
Octopodidae and the trichotomy formed by
Argonauta, Tremoctopus and Ocythoe. All
nodes are supported by boot strap values over
50% (Fig. 1) except one relationship within the
octopodids. Although all equally parsimonious
trees identify O. Macrotritopus as the sister
taxon of Hapalochlaena and the undescribed
genus, bootstrapping does not support the node
and it is not included on Figure 1. The lowest
bootstrap value among the twelve nodes was
Figure 1. Results of 100 replicate bootstrapping analyses are indicated on the strict consensus tree of the 177
equally most parsimonious trees discovered at 191 steps (CI = 0.429; RI = 0.678). In addition to the relationships indicated on the figure, all 177 most parsimonious trees identified O. (Macrotritopus) as the sister taxon
to the species pair Hapalochlaena and the undescribed genus. The few characters informative for the limited
number of exemplars of the benthic octopuses (octopodids) included in the analysis argue that these relationships must be more closely examined before being fully accepted.
CLADISTIC ANALYSIS OF THE OCTOPODA
,Vampyroteuthis
. Cirroteuthis
Opisthoteuthis agassizi
o
\
Opisthoteuthis californiana
Grimpoteuthls
Eledonella
apetella
phitretus
Vitreledonella
Haliphron
Tremoctopus
Ocythoe
Argonauta
Pareledone
Bathypolypus
Benth octopus
"8
Reroctopus
Q.
Q.'
Oct. bimaculatus
8
Oct. ornatus
Eledone
Graneledone
Tetracheledone
Velodona
Cistopus
Robsonella
Scaeurgus
Oct. (Maaotritopus)
Hapalochlaena
undesc. gen. sp.
317
318
J.R. VOIGHT
57%, ten nodes were supported at 70% and six are present in Grimpoteuthis, but absent in
nodes at 85% or above (Fig. 1).
more derived cirrates, include the pallial (fin)
The range of consistencies of the eight arteries being the second, rather than the first,
characters of loss or reduction are identical branch of the dorsal aorta (57), the lack of a
with those of characters of acquisition included construction in the dorsal aorta (53) and an
in the analysis (range for both 0.200 to 1.000). elongate penis that is comparatively free of the
Characters of loss and reduction, thus, do offer accessory glands (24), which in members of this
information that may be important to phylo- taxon are positioned near the testis. Autagenetic reconstruction, as Begle (1991) argued, pomorphies of Grimpoteuthis include the
despite the perception that problems in assess- comparatively shallow web (9) and the pallial
ing homology force rejection of negative arteries originating distant from the heart (54).
Optimizing character change with delayed
characters (Young & Vecchione, 1996).
The monophyly of the group formed by the transformation finds the half-orange gills (45)
cirrates and incirrates is supported by several to be convergent in Grimpoteuthis and
synapomorphies, including the presence of at Opisthoteuthis.
most one pair of fins (character number 1),
The above characters of Grimpoteuthis, illuseight arms (16) carrying sessile suckers which trated in Cirroteuthis umbellata (Fischer, 1883),
originate immediately adjacent to the buccal the type species of Grimpoteuthis by Ebersbach
mass (7), a reduced number of gill lamellae (1915), offer a new, restricted definition of the
(47), a common pallial artery (55), photo- genus Grimpoteuthis. This restriction is a critisensitive vesicles located in the stellate ganglion cal first step in building a cirrate classification
on the mantle wall (60), the presence in females based on evolutionary history rather than on
of radially arranged spermathecae in the overall morphological similarity. Whether the
oviductal gland (23) and the systematic heart presence of a homodont radula characterizes
located ventral to the viscera (52). In addition, this genus remains uncertain. Voss & Pearcy
the common ancestor of Vampyroteuthis, the (1990) report the radula to be absent in specicirrates and the incirrates is reconstructed as mens of G. bathynectes, but present in those of
lacking an ink sac (51); the organ is defined as congeners. The character may convey informaan apomorphy of the incirrates. As stated tion at a level other than that discussed here or,
above, I consider the organ to have been lost if its absence in G. bathynectes is a synapoindependently in Vampyroteuthis and the morphy shared with derived cirrates, it may
cirrates rather than to be absent in the ancestor. signify paraphyly of specimens assigned to the
The presence of an ink sac in a Cretaceous genus Grimpoteuthis.
fossil cirrate, Palaeoctopus newboldi WoodThe monophyly of the genus Opisthoteuthis
ward, 1896, with a broadly U-shaped fin is well-supported by the numerous arm suckers
support (Roger, 1944) and in all non-octopod (13), the caecum ventral to the stomach (40),
coleoid cephalopods, support this non- the dramatically enlarged suckers of males (27)
parsimonious scenario.
and the bi-lobed digestive gland (44) (as noted
The monophyly of the cirrates is supported by Ijima & Ikeda (1895, Plate XXXIII) and
by seven synapomorphies that include the Meyer (1907) in O. depressa Ijima and Ikeda,
presence of the fin support modified from the and by Pereyra (1965) in O. californiana).
gladius (2) and web nodules (11), a narrow These characters offer a new definition of the
mantle aperture around the funnel (49), a genus. The half-orange gills (45), under delayed
ventral mantle septum restricted to the anterior transformation, are also considered to be apomantle cavity which is not homologous with morphies of this genus. The disk-shaped body
that of incirrates (66), muscular septa in the typical of Opisthoteuthis, although not conarms (5), the absence of the posterior salivary sidered here, may also be a synapomorphy of
gland from the mantle cavity (35), loss of the the genus that has contributed to their invasion
right oviduct (20), and, I argue, loss of the ink of comparatively shallow-water habitats (Voss,
sac (51). When character change is optimized as 1988b). Rather than using their fins for
accelerated rather than delayed, the half- propulsion, as do most cirrates (Aldred et at,
orange arrangement of the gills (45) is also 1983), disk-shaped members of Opisthoteuthis
considered to be a synapomorphy of the swim by moving large amounts of water by
opening and closing the web (Pereyra, 1965).
cirrates.
This analysis discovers Grimpoteuthis to The muscles required for this swimming mode
be basal among the cirrates, as Voss (1988a) may define the body shape of preserved
suggested. Plesiomorphic character states that specimens. The revised generic definitions of
CLADISTIC ANALYSIS OF THE OCTOPODA
Opisthoteuthis and Grimpoteuthis are more
restrictive than those in current usage and
may necessitate recognition of additional
genera.
The relationships identified here, strongly
supported by significant bootstrap values, indicate that Voss' (1988as) Opisthoteuthidae, consisting of Opisthoteuthis and Grimpoteuthis, is
paraphyletic. The characters cited as diagnostic
of that family (single, deep web, small mantle
aperture, short funnel with an inverted Vshaped funnel organ, half-orange gills, a U- or
V-shaped shell, short cirri, variable radula and
bell-shaped or depressed body) are here discovered to be symplesiomorphies or convergences. Although this analysis did not include
specimens of Stauroteuthis, Robson's detailed
description of arterial branching in Chunioteuthis gilchristi (Robson, 1924) suggests that it
is among the derived cirrates; its secondary
web, reported by Voss (1988a), links it with
Cirroteuthis. Voss (1988a) assigned Chunioteuthis to the Stauroteuthidae and suggested
that it is synonymous with Stauroteuthis.
Although the secondary web, the saddleshaped shell and an exceptionally elongate
common pallial artery (apparently linked to the
depth of the fin support) were, among the specimens examined, autapomorhires of specimens
of Cirroteuthis, their reported presence in
specimens of Cirrothauma (Aldred et al, 1983)
support the hypothesis that these genera form a
monophyletic group.
The medial posterior salivary gland cephalad
of the bifurcation of the dorsal aorta, depicted
by Meyer (1907) in G. umbellata, has rarely
been reported in cirrates. The organ is uniquely
present in one of two specimens in the lot of
O. agassizi examined. This single specimen
questions whether the loss of the gland can be
considered a synapomorphy of the cirrates, and
whether the position of the gland dorsal to the
crop can be an apomorphy of the incirrates.
This apparent intra-specific variation suggests
that the character may vary in a complex
manner with size and/or sex.
The monophyly of the incirrates is supported
by several synapomorphies. These include the
negative characters: complete loss of the fins
(1), cirri (6) and all remnants of the gladius (2)
and a reduction in the depth of the web (9). The
clade is supported by the positive characters of
multicuspid rachidian teeth (32), paired posterior salivary glands (36), an esophageal crop
with a narrow opening (38), the caecum positioned ventral to the stomach (40), the attachment of the branchial gland to the mantle wall
319
for its length (50), the extensive ventral mantle
septum (66) which is not homologous with that
of cirrates and nerves emerging in a star-burst
pattern from the stellate ganglion (62) which is
lateral to the gill (61). As discussed above,
although the presence of an ink sac (51) is
identified as uniting the incirrates, I argue that
it should be viewed as a plesiomorphic character that was lost in convergence in Vampyroteuthis and the cirrates. The hectocotylus with a
ligula (26) and the posterior salivary glands lying
dorsal to the crop (35), when viewed under the
assumption of accelerated transformation, also
unify the incirrates, with reversals in Japetella
(26) and Amphitretus and Vitreledonella (35).
In addition, based on his study of the central
nervous system, Young (1988; 1989) cited the
extreme condensation of the brain, the strongly
developed vertical lobe system and the division
of the cristae of the statocyst into nine units as
unifying the incirrates.
The Bolitaenidae are basal incirrates. The
monophyly of the group is supported by characters that include muscular septa in the arms (5),
sexually dimorphic posterior salivary gland size
(19), multicuspid lateral teeth (33), the caecum
within the digestive gland membrane (41) and
the gastric artery carrying blood only to the
stomach (58). Under delayed character transformation, the posterior salivary glands being
positioned dorsal rather than cephalad to the
crop (35) also defines the clade. Potential
adaptations of the bolitaenids to mid-water
existence include the septa in the arms and
sexually dimorphic posterior salivary glands
(Voight, 1995). Bolitaenid plesiomorphies may
include the absence of the supra-branchial
commissure, a character not included in this
analysis. Young (1977) reported this commissure to be present in the cirrate and incirrate
taxa that this analysis finds to be derived, and
considered its absence in bolitaenids to be an
adaptation to their mid-water existence. The
commissure has been argued to increase the
fine nervous control of the arms (Young, 1971)
and to be homologous in cirrates and incirrates,
despite the difference in its anatomical position
in the two groups (Young, 1977). In cirrates, the
commissure lies posterior to the cerebrobranchial connective; in incirrates, it is anterior
to it. When examined in light of the relationships discovered here, the commissure appears
to be an adaptation to the loss of the tentacles;
the difference in its position between cirrates
and incirrates may evidence its convergent evolution. The complex septa in bolitaenid arms
may help compensate for the absence of the
320
J.R. VOIGHT
commissure by increasing the fine control of
the arms.
The Octopodidae and what I informally
refer to as the pelagic clade, containing
Amphetritus, Vitreledonella, Haliphron, Tremoctopus, Ocythoe and Argonauta, are sister
taxa. This relationship is supported by the W
(or W ) shaped funnel organ (48), the pallial
artery being the first branch of the dorsal aorta
(57), the many nerves that emerge from the
stellate ganglion (63), a muscle extending from
the dorsal stomach to the sheath over the dorsal
viscera (65) and the calamus on the oral arm
surface (31). Characters that unite the clade
assuming delayed change include the development of a hectocotylus with a ligula (26) (if this
character is convergent in Eledonella) and
equal number of suckers on all arms (8);
assuming accelerated change, the large number
of suckers occur on the arms (13) also unites
these taxa.
The pelagic clade is united by synapomorphies that include a long, conic ligula (29),
the parasagittal rectum (43), the dorsal
systemic heart (52) and the gastric artery which
carries blood to the stomach, crop and digestive
gland (58). The cephalad posterior salivary
gland (35) also supports the gTOup assuming
delayed transformations, as does the bulbous
diverticulum of the penis (24), assuming that it
is reversed in Vitreledonella.
The monophyly of the four argonaut genera
is supported by the hectocotylus that is held in a
pouch (28), the calamus being on the lateral
arm surface (31), tricuspid rachidian teeth (32),
the well-developed funnel-mantle locking
apparatus (46), separate right and left pallial
arteries (55) and the restricted mantle septum
(66). Assuming delayed character change, the
bulbous penial diverticulum (24) and the many
arm suckers (13) also unify the group.
The monophyly of Ocythoe, Tremoctopus
and Argonauta is supported by the dorsal arms
having the most suckers (8), the skin extending
between sucker acetabula (12), strong sexual
size dimorphism (18), the posterior salivary
glands being dorsal (35) to the broadly open
esophageal crop (38) and the increased number
of outer gill lamellae (47). Despite the wellsupported monophyly of the clade, relationships among these distinctive taxa cannot be
further resolved with the characters analyzed
here.
Amphitretus and Vitreledonella are recognized here as sister taxa. Characters that support this relationship include the crop being
cephalad to he digestive gland (39), the caecum
lying dorsal to the stomach (40), multiple
vesicles in the photosensitive vesicle (60), the
same number of suckers on all arms (8) and,
under accelerated change, the cephalad posterior salivary glands (35). Required changes in
the family-level classification of these taxa are
discussed below. Although Thore (1949) argued
that the multicuspid lateral teeth (33) united
the bolitaenids and Amphitretus in the
Ctenoglossa, this group emerges as diphyletic in
this analysis. Among the incirrates, the multicuspid rachidian teeth are plesiomorphic; the
unicuspid rachidian teeth of Bathypolypus and
the tricuspid rachidian teeth of the argonauts are
derived. The multicuspid lateral teeth are convergent in the bolitaenids and Amphitretus.
A study of the pelagic clade would greatly
increase our knowledge of radula function.
Among these closely related taxa, differences in
radular dentition meet or exceed levels
known elsewhere in the class (see, however,
Doguzhaeva & Mutvei, 1992).
The monophyly of the Octopodidae is supported by this analysis. The stylets (2) (which
are suggested to be convergent with those in
Haliphron and Tremoctopus), the muscle
encircling the dorsal aorta at the esophagus'
entry to the stomach (64), in females the
presence of a cervix (22), and the oviducts that
originate from the common oviduct at an acute
angle (21), unite the clade. It may be notable
that among octopodids, only in specimens of
Eledone (which none of the 177 shortest trees
considers to be basal) are both the cervix of
females and the calamus of males absent,
suggesting that these characters are functionally linked. Whether the arms with the same
large number of suckers (8; 13) and the dorsal
position of the posterior salivary glands (35)
also unify the benthic octopuses depends on the
assumptions of the rate of character transformation.
The incirrate stylets evolved de novo, independent of the plesiomorphic gladius. Differences in stylet biomineralization among the
octopodids (R.B. Toll, pers. comm.) and the
unusual stylets in specimens of Haliphron,
neither of which was considered as a separate
character state here, support this discovery.
Engeser's (1988) and Berthold & Engeser's
(1987) reconstructions of Palaeoctopus as a
member of the stem-group of incirrates cannot
be accepted, as they assume that the cirrate fin
support is a plesiomorphy of the incirrates.
Although the few recognized species of midwater incirrates likely underestimate the diversity of these incirrate groups (Voight, unpubl.
321
CLADISTIC ANALYSIS OF THE OCTOPODA
data), the over 200 nominal species of octo- identifies convergence of these taxa in this
podids (Hochberg et al, 1992) appear to character.
constitute an evolutionary radiation. Despite
In situ study of the digestive system also prothe group's unique evolutionary success, no key vided much information on incirrate relationinnovation has been identified, suggesting that ships. As Joubin (1918) and Thore (1949)
their diversification relates to their benthic noted, the spatial relationships of the viscera in
life style.
Vitreledonella and Amphitretus are shifted
The one relationship discovered among cephalad; the esophageal crop is immediately
the octopodids included, and supported by a behind the brain and the stomach is closer to
57% bootstrap value, is most surprising. This the head than to its plesiomorphic position at
analysis finds an undescribed octopodid from the posterior tip of the mantle cavity. The
hydrothermal vents at the East Pacific Rise to caecum is dorsal in position, and the gonad is
be a sister taxon to Hapalochlaena from centered on the dorsal digestive gland, rather
shallow-water reefs of the Indo-West Pacific. than being ventral to that gland. What has
All 177 equally parsimonious trees also identify escaped notice is that a similar but less extreme
O. (Macrotritopus) as the sister taxon to this spatial shift affects the argonauts. The shift is
species pair, although significant boot strap most easily seen in submature specimens in
values do not support this relationship. Charac- which the gonad does not displace other organs
ters that support this surprising relationship from the posterior mantle, as it does in the
are the coarse tubes composing the posterior specimens illustrated by Naef (1923: Fig. 450 &
salivary glands (34), a broadly open crop (38), a 466). Although it may seem surprising that such
caecum with one or part of one spiral (42), the an unusual anatomical arrangement could go
presence of a common pallial artery (55) the unnoticed, neither Ijima & Ikeda (1902) nor
first branch of the left pallial artery being very Sasaki (1929) mentioned this aspect of the
close to its origin (56) and many arteries carry- anatomy of Amphitretus, despite having at least
ing blood from the aorta to the crop (59). This partially dissected specimens of the taxon. This
congruence is unusual among the 20 characters anatomical arrangement may minimize the
that vary informatively (Le., differ in state in at effect of a full digestive system on the center of
least two taxa) among the octopodids. The gravity. By shifting the crop and stomach
comparatively few informative characters anterior, the weight of ingested prey remains
concerning the octopodids, a group represented not only along the midline of the body, but also
by few exemplars, argue that this suggested near the head to increase the animal's stability.
relationship should not be given undue
Taxonomic divisions at the level of family
emphasis.
among the incirrates are generally supported by
Arterial branching of the dorsal aorta to the this analysis, I argue that two, however, must be
digestive organs discovered by examining synonymized. The first is Idioctopodidae, a
organs in situ shows parallel changes in the taxon Taki (1962; 1963) described based on two
cirrates and incirrates. In Vampyroteuthis, an specimens. His specimens had characters virtuartery from the dorsal aorta flows to the digest- ally identical with those of Amphitretus, the
ive gland and branches to supply other digest- fusion of the mantle and funnel, multicuspid
lateral teeth, and a long, conic ligula (with or
ive organs with blood (Young, 1964), a second
branch of the aorta nearer the head supplies the without papillae). As the taxa share characters
pallial arteries. This pattern is essentially that that define a genus, they cannot be maintained
seen in Grimpoteuthis and bolitaenids. Among as separate families. As Hochberg et al. (1992)
derived cirrates and incirrates, the first branch suggested, Idioctopodidae is a junior synonym
of the aorta supplies blood to the mantle or fins, of Amphitretidae.
the second artery supplies the viscera. Among
The recognition of the Vitreledonellidae as
some octopodid taxa, additional arteries Irom distinct also appears to be inappropriate.
the dorsal aorta supply blood directly to the Although members of Vitreledonella do not
esophageal crop. Members of the pelagic clade share the medial fusion of the mantle and
share an anatomy similar to that of the octopo- funnel that is unique to those of Amphitretus,
dids, but the arteries to the esophageal crop assigning these sister taxa to separate families
branch from the gastric artery. The artery in the based on what is perceived to be 'sufficient'
pelagic clade is short, as the crop is either difference undermines the information that the
immediately dorsal to the stomach or curves taxonomy could convey. The classification of
back to almost touch the stomach. The differ- these genera in the same family, as is proposed
ence in the source of the blood supply clearly here, would reflect that, cladistically, they are as
322
J.R. VOIGHT
closely related as are members of Eledonella
and Japetella. If taxonomic categories are to
convey information on shared evolutionary
history, the classification must reflect our
current understanding of that history. Continuing to regard these taxa as separate families
assigns taxonomic rank based on a criterion
other than evolutionary history. In addition,
synonymizing Vitreledonellidae with the more
senior Amphitretidae would make the application of the taxonomic rank of family consistent
among the incirrates.
Young (1989; 1995) and Doyle, Donovan &
Nixon (1994) have advocated elevating the
cirrates and incirrates to ordinal status. This
analysis offers no insight into the issue other
than to demonstrate the monophyly of the
groups. As the cladistic relationships among
and between the other coleoid groups of
sepiolids, squids and cuttlefish are unresolved,
the question may be considered in a more
appropriate context after those relationships
are established. Elevating the rank of the octopod suborders now may be premature, as it
might set a precedent that would complicate
taxonomy of other groups.
Kear, Briggs & Donovan's (1995) comparison of mantle musculature among fossil
coleoids, extant squid and a generic octopod,
suggests that either octopods are a monophyletic group separate from squids, or that the
monophyletic group of Recent squids and
cuttlefish includes the Jurassic cephalopods
they discussed. These authors fail to consider
that the acquisition of external and internal
tunics of connective tissue on the mantle
musculature does not define a clade; it may be a
symplesiomorphy of modern squids. The
absence of the tunics in octopods cannot be
cited as evidence of their separate origin
without having examined the character in specimens of Vampyroteuthis. Young (1964) reports
longitudinal mantle muscles, the character that
these authors suggest defines octopods, to be
nearly absent in specimens he examined,
supporting the hypothesis that the tunics are
lost in octopods rather than that octopods are
unrelated to squids.
The cladistic relationship of the Octopoda
revealed here offer new insight into the evolution of these animals, which occupy every
marine environment. These hypotheses of
phylogenetic relationships should be reexamined from different perspectives and
re-analyzed as additional data sets become
available. Continued study of this lineage and
its diversification through the marine realm
from multiple perspectives will increase our
understanding of the history of these animals
and of the oceans themselves.
ACKNOWLEDGEMENTS
Nancy Voss at the Invertebrate Collections of
the Rosenstiel School of Marine and Atmospheric
Science, University of Miami Marine Laboratories,
Terry Gosliner at the California Academy of
Sciences, George Davis at the Academy of Natural
Sciences Philadelphia, and Bruce Marshall, Museum
of New Zealand allowed study of specimens in their
care that were vital to this research. Examination of
additional specimens in the care of F. Naggs at the
Natural History Museum (London) and C.F.E.
Roper at the United States National Museum was
also important to the research reported here. A.
Perez assisted with the anatomical analysis of female
reproductive systems. Comments by R.E. Young and
A.C. Driskell on earlier attempts to resolve relationships among octopods were very helpful. B. Ballard &
P. Herendeen assisted with computer analyses, R.
Bieler with key translations. The paper benefitted
gTeatly from comments by the symposium editors and
outside reviewers. This research was partially funded
byNSF(DEB-9306925).
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324
JR. VOIGHT
relationships within coleoid cephalopods. AmeriPaleontology of the Cephalopods (M.R. Clarke &
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Diego.
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Appendix 1. List of the specimens examined, includoctopods (Mollusca: Cephalopoda) of the northing the catalogue number of each lot. ANSP =
eastern Pacific. Proceedings of the California
Academy of Natural Sciences, Philadelphia; CAS =
Academy of Sciences, 47:47-94.
California Academy of Sciences; FMNH = Field
Museum of Natural History; NMNZ = National
Voss, N.A. & Voss, R.S. 1983. Phylogenetic relationMuseum of New Zealand; UMML = Rosenstiel
ships in the cephalopod family Cranchiidae
School of Marine and Atmospheric Science, Univer(Oegopsida). Malacologia, 23: 397-426.
WILLASSEN, E. 1986. Haliphron atlanticus Steenstrup sity of Miami.
(Cephalopoda: Octopoda) from the coast of
Vampyroteuthis infemalis CAS 030393; CAS 030110;
Norway. Sarsia, 71: 35^40.
Cirroteuthis muelleri CAS 067787, CAS 067788;
YOUNG, J.Z. 1971. The anatomy of the nervous system Grimpoteuthis bathynectes CAS 067789 (paratypes);
G. sp. A UMML 31.2468; O. agassizi UMML 31.2494;
of Octopus vulgaris. Oxford University Press,
Opisthoteuthis califomiana FMNH 278029, CAS
Oxford.
020795; Eledonella pygmaea UMML 31.1587; E. sp. A
YOUNG, J.Z. 1977. Brain, behaviour and evolution of
cephalopods. Symposia of the Zoological Society of UMML 31.1583; Japetella diaphana UMML 31.1375;
Amphixretus pelagicus UMML 31.1564, UMML
London, 38: 377^34.
31.2028, UMML 31.2717, UMML 31.2718, UMML
YOUNG, J.Z. 1988. Evolution of the cephalopod
31.2719; Idioctopus gracilipes NMNZ M.118261
brain. In: The Mollusca, 12: Neontology and
Paleontology of the Cephalopods (M.R. Clarke & (Specimen too damaged to be included in analysis);
VitreledoneUa richardi FMNH 78335, UMML
E.R. Trueman, eds), 215-228. Academic Press, San
31.1566, UMML 31.1467; Haliphron atlanticus
Diego.
FMNH 278028, UMML 31.927; Ocythoe tuberculata
YOUNG, J.Z. 1989. The angular acceleration receptor
UMML 31.1570; Tremoctopus violaceus UMML
system of diverse cephalopods. Philosophical
Transactions of the Royal Society of London, B325: 31.2024, UMML 31.244: Argonauta argo FMNH
279608; Pareledone charcoti FMNH 278067, UMML
189-238.
31.2561; Bathypolypus arcticus FMNH 278079,
YOUNG, J.Z. 1995. The classification of Octopods. In:
FMNH 278080, FMNH 278026; Benthoctopus
Abstracts 12th international Malacological
Congress, Vigo, Spain. (A. Guerra, E. Rolan & F. hokkaidensis FMNH 278066; Pteroctopus tetracirrhus
UMML 31.1971; Octopus (O). bimaculatus FMNH
Rocha, eds). 367. FE1TO, Vigo.
278030; Octopus (C.) ornatus FMNH 278027; O.
YOUNG, R.E. 1964. The anatomy of the Vampire
(Macrotritopus) horridus CAS 077987, CAS 077978,
Squid. Ms. Thesis. University of Southern CaliEledone cirrhosa FMNH 278032; Graneledone pacifornia, Los Angeles.
YOUNG, R.E. 1972. Function of extra-ocular photo- fica FMNH 278078, UMML 31.2541, UMML 31.2542,
receptors in bathypelagic cephalopods. Deep-Sea CAS 061434; G. antarctica UMML 31.1667; Tetracheledone sptnicirris UMML 31.249, UMML 31.143;
Research, 19: 651-660.
Velodona togata UMML 31.2720; Cistopus sp. ANSP
YOUNG, R.E. 1995. Aspects of the natural history of
A6394; Robsonella fontaniana ANSP A638O; Scaeurpelagic cephalopods of the Hawaiian Meso-pelagicgus unicirrhus UMML 31.2199, UMML 31.1414;
boundary region. Pacific Science, 49:143-155.
Hapalochlaena lunulata FMNH 279609; undescribed
YOUNG, R.E. & VECCHIONE, M. 1996. Analysis of
gen. and sp. FMNH 278064.
morphology to determine primary sister-taxon
Appendix 2. Reported for each operational taxonomic unit is the state assigned to each of the characters
analyzed. '.' indicates character state could not be scored or was noted to be polymorphic, see text for definition of characters and states. * indicates multistate character which was analyzed unordered.
1 11111 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3
12 3 4 5 6 8 9 0 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
Vampyroteuthis infemalis 0 0 0 0 0 0 0 11 0 0 0 0 0 0 0 0 0 0 . 0 0 . 0 0 . 0 0 . . . 0 0
Cirroteuthis muelleri
1 1 1 0 10 1 . 0 0 1 1 0 0 0 1 0 0 . 1. .1 1 1 0 0 . . . 0 .
Grimpoteuthis bathynectes 1 1 0 0 1 0 1 1 1 0 1 0 0 0 0 1 0 0 . 1 . 0 1 0 0 0 0 . . . 0 .
Opisthoteuthis agassizi
110 0 10 1 1 0 0 1 0 1 0 0 1 0 0 0 1. .1 1 0 0 1 . . . 0 .
O. califomiana
1 1 0 0 . 01 0 0 0 1 0 1 0 0 1 0 0 . 1 . 0 1 1 0 0 1 . . . 0 .
Eledonella
2 3 10 11 1 1 1 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 1 0 0 0 0 0 1
Japetella
2 3 0 0 1 11 1 1 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 1
Amphitretus
2 3 1 0 0 1 1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 2 0 1 0 0 1 0 11
Vitreledonella richardi
2 3 0 0 0 1 10 1 . 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 1 0 11
Haliphron atlanticus
2 2 10 0 1 12 10 0 0 1 0 0 10 0 0 0 0 0 2 0 10 1 1 1 2 2
Ocythoe tuberculata
2 3 0 1 0 1 1 1 1 0 0 1 1 0 11 1 1 0 0 0 0 2 0 1 0 1 1 0 2 2 0
CLADISTIC ANALYSIS OF THE OCTOPODA
Tremoctopus violaceus
Argonauta argo
Pareledone charcoti
Bathypolypus arcticus
Benthoctopus hokkaidensis
Pteroctopus tetracirrhus
Octopus bimaculatus
Octopus omatus
Macrotritopus horridus
Eledone cirrhosa
Graneledone pacifica
Tetracheledone spinicirris
Velodona togata
Cistopus sp.
Robsonella fontaniana
Scaeurgus unicirrhus
Hapalochlaena lunulata
undescr. gen. & sp.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Vampyroteuthis
Cirroteuthis
Grimpoteuthis
O. agassizi
O. califomiana
Eledonella
Japetella
Amphitretus
Viireledonella
Hahphron
Ocythoe
Tremoctopus
Argonauta
Pareledone
Bathypolypus
Benthoctopus
Pteroctopus
O. bimaculatus
O. ornatus
O. horridus
Eledone
Graneledone
Tetracheledone
Velodona
Cistopus
Robsonella
Scaeurgus
Hapalochlaena
undescr. gen.
3 33 3 34
5 678 90
0 000 00
1 . .0 0 0
1 . .0 0 0
.0 0 0
1 . 0 0
21 2 0
21 2 0
0 2 21
01 21
01
0 0
2
01
0 0
2
01
2
0 0
2
2
0 00
2
10 0
2
10 0
2
2 01
2
2 0 1
2
101
2
2 0 0
2
0 0
2
0 0
2
0 0
2
2 0
2
2 0
2
2 0
2
10
2
10
201
300
200
200
200
200
200
200
2 0
2 0
3 0
2 0
200
200
200
2 0
3 0
300
0 1 2 1 2 0 1 1 0 0 0 10 0 0 0
1 2 0 1 1 0 0 0 10 0 0 0
0
0 1 0 0 0 0 1 10 0 0 1
0
0 1 0 0 111 0 0 0 0 1
0
0 1 0 0 110 0 0 0 01
0
0
0 0
01 0 000 1
0
0 10
0 0 0 000 1
0
0 0 0
1 0 0 0 0 01
0 1 1 0 0 0 0 11
0
0 0 0
0 1 1 0 0
0 1 1 0 0 0 0 11
1 1 1 0 0 0 0 11
0 1 1 10
0 1 0 1 0 0 0 0 1 10 0 . . . .
0 1 . 1 1 10 1 1 1 1 0 0 . 0 1 .
0 1 . 10 0 . 1 0 0 1 0
0 1 0 1 0 0 10 0 1 0 . . 0 .
0 1 0 1 1 0 1 1 11 0
0 10 10 0 1 0 0 10 0 . . . .
0 10 10 0 0 1 0 0 10
4 4 444
12 3 4 5
0 0 000
0 0 000
0 0 00 1
0 0 01 1
0 0 01 1
10 0 0 0
10 0 0 0
0
0 0
0
0 0
0 0 10 0
0 0 10 0
0 110 0
0 0 10 0
0 0 000
0 0 000
0 0000
0 00
0 00
0 00
0 00
0 00
0 0000
0 0000
0 0000
0 0000
0 0000
0 0 10 0
0 0000
0 0 01 0
444 4 5 55 5
6 7 8 9 0 12 3
0 0 0 0 0 10 0
0 1 0 10 11 1
0 1 0 10 11 0
0 1 0 10 11 1
0 1 0 10 11 1
01 0 0 10 1 0
01 0 0 10 1 0
0 1 1 . 10 0 0
01 1 01 0 0 0
1 11 0 1 0 0 0
1 0 10 10 0 0
1 0 10 10 0 0
1 0 10 10 0 0
0 1 10 10 1 0
0 1 10 11 1 0
01 1 01 1 1 0
0 1 2 0 10 1 0
0 1 10 10 1 0
0 0 10 10 1 0
0 1 10 10 1 0
0 0 10 10 1 0
01 2 0 111 0
01 .0101 0
0 1 10 10 1 0
0 0 10 10 1 0
0 1 10 10 1 0
0 0 2 0 10 1 0
01 .0101 0
0 0 10 1 1 1 0
325
12 0 1 0
12 0 10
10 0 10
1 0 11 0
10 0 10
10 0 1 0
10 0 10
10 0 10
1 0 11 0
10 0 10
110 1 0
.001 0
.001 0
.001 0
10
. 0 10
..01 0
.001 0
.001 0
55 5 5 55
45 6 789
000 000
0 1 0 10 0
11 0 0 0 0
0 1 0 1.0
0 1 0 10 1
1 10 0 1 0
01 1 01 0
11 0 12 0
0 .0 1 20
000 1 20
00 120
00 1 20
00 1 20
11
0 0
11
0 0
01
01 0
01 1 0 1
000 0 1
00110 2
01 1 1 01
10 0 1 01
1 . .10 0
0 1 0 10 2
01 110 0
0 1 0 10 0
0 0 110 0
01 110 2
0 1 110 2
1 11 2 2 0 1
1 10 2 2 0 1
000 1 0 1
0 0 0 0 00
000 1 0 1
000 .0 1
000 1 0 1
000 1 0 1
000 1. . 0
0 0 0 0 10 1
0 0 0 11 0 1
000 1. . 1
000 1. . 1
000 1. . 1
0 0 0 11 0 1
000 1. . 1
000 1. . 0
0 0 0 11 0 0
6 6 66
0 12 3
0 0 00
10 0 0
10 0 0
10 0 0
.000
1110
1110
2 0 11
2 0 00
1111
.111
.111
.10 0
110 1
110 1
1111
1111
1111
1111
.111
1111
.111
.111
.111
.111
.111
.111
.111
.111
6
4
0
0
0
0
1
0
0
1
0
0
0
0
0
1
1
1
66
56
00
01
01
0 1
1 1
02
02
1 2
02
1 1
1 1
0 1
0 1
1 2
1 2
1 2
12
12
12
12
12
12
12
12
12
12
02
12
1 1 2