MYRIAPODA
Henrik Enghoff
Natural History Museum of Denmark (Zoological Museum)
2005
<page and fig. references, “RFB”, refer to
Ruppert, Fox & Barnes: Invertebrate Zoology, 7th. ed. 2004.>
There are four classes of Myriapoda, viz. Chilopoda (centipedes, DA: SKOLOPENDRE),
Diplopoda (millipedes, DA: TUSINDBEN), Pauropoda (pauropods, DA: PAUROPODER) and
Symphyla (symphylids, DA: SYMFYLER).
THE POSSIBLE MONOPHYLY OF MYRIAPODA AND THE RELATIONSHIPS
BETWEEN THE MYRIAPOD CLASSES
(Also read “Phylogeny of Tracheata” in RFB p. 718-720”)
Myriapod phylogeny is unsettled, but possibly the four myriapod classes plus the class
Hexapoda constitute a monophyletic 'subphylum' Uniramia, also known as Atelocerata
and Tracheata.
The presence of numerous legs, which has given the myriapods their name, is obviously a
symplesiomorphy. Within the framework of a monophyletic Uniramia, several sistergroup relationships have been proposed:




(Hexapoda) – (Myriapoda)
(Hexapoda) – (Symphyla)
(Hexapoda) – (Chilopoda)
(Chilopoda) - ((Hexapoda) – (Symphyla+Pauropoda+Diplopoda))
The following traits have been mentioned as possible synapomorphies for the four
myriapod classes, i.e., as arguments for a monophyletic group Myriapoda (numbering
continued from first part of compendium):
1. No mandibular abductor muscle; abduction of mandibles effectuated indirectly by
the movable anterior tentorium (Fig. 1)
2. Median eyes never present (in Crustacea, the median eyes are represented by the
nauplius eye, in Hexapoda, they are represented by the ocelli .
1
3. No perforatorium in the spermatozoa (Fig.2: "1-laget acrosom" (one-layered
acrosome), in contrast to the two-layered acrosome in "Insecta" which is
considered to be the original state)
All these have been considered reductional characters and therefore of limited value. The
absence of an abductor muscle may, however, be primary, i.e., a plesiomorphy, and the
same may be true of the movability of the tentorium (Klass & Kristensen i Deuve ed.,
2000). The presence of the anterior tentorium in itself appears as an apomorphy
immediately below the myriapod level, i.e. as an apomorphy for Uniramia.
The characters invoked in favour of the hypothesis of a sister-group relationship between
Symphyla and Hexapoda are possibly symplesiomorphies or convergencies:
4. Three pairs of buccal appendages (mouthparts) (RFB: fig. 20-7B-C, p. 710).
Ruppert & Barnes follow Manton in rejecting this similarity based on differences
between the buccal appendages of symphylids and hexapods: this suggests that
the presence of three pair of buccal appendages could be convergent.
5. Second pair of maxillae forming a labium (‘lower lip’). This character, too, may
be regarded as a convergence. The morphological interpretation of the ‘lower lip’
in Diplopoda and Pauropoda is still under debate (cf. below).
The basis of the hypothesis of a sister-group relationship between Chilopoda and
Hexapoda is tenuous:
6. In both groups the gonopores are located at the posterior end of the body, unlike
the situation in Diplopoda, Pauropoda and Symphyla (‘Progoneata’, cf. below)
where they are placed near the anterior end. Out-group comparison (with
Crustacea and Chelicerata) is of no help here, but the posterior gonopore is most
likely the original condition within Uniramia and thus cannot be used as an
argument in favour of a Chilopoda-Hexapoda sister-group relationship.
There are several similarities between Hexapoda on the one hand, and Diplopoda+
Pauropoda+Symphyla on the other. They are all quite subtle, and none is persuasively
synapomorphic. One example is:
7.
The eversible coxal sacs which are found in Symphyla (RFB: p. 711), certain
Diplopoda (Penicillata, Colobognatha, Nematophora) and certain (‘primitive’)
Hexapoda. The coxal sacs are probably symplesiomorphic and have become lost
in Chilopoda, Pauropoda, many Diplopoda and most Hexapoda).
Wheeler et al. (1993) analysed arthropod relationships using one morphological and two
molecular (DNA) data sets. Their analysis included Diplopoda and Chilopoda (but not
Symphyla and Pauropoda) as well as numerous groups of Hexapoda, Crustacea and
Chelicerata. Both molecular data seta indicated that Diplopoda and Chilopoda were more
closely related to each than to any other the other included groups and thus support the
hypothesis of myriapod monophyly. (The analysis of the morphological character set – a
2
character set with several flaws – did not resolve the relationship between Diplopoda,
Chilopoda and Hexapoda.)
It was suggested above that Chilopoda differ from the other myriapod classes. The latter,
viz., Diplopoda, Pauropoda and Symphyla, together constitute the group Progoneata. This
name (‘pro’: in front, ‘gon-’: having to do with sexual organs) refer to a possible
synapomorphy between the three classes, viz.:
8. The gonopore is placed anteriorly on the body (cf. the discussion under character
6).
Other possible synapomorphies between the three classes (i.e., autapomorphies for
Progoneata) are:
9. clypeus and labrum are fused (in Chilopoda and Hexapoda the labrum is separated
from the clypeus by a suture and is ± movable. RFB: fig. 20-2C, p. 705, shows the
clypeus in a chilopod; the labrum is not visible, but is placed in ’the black hole’
between clypeus and first maxilla.
10. The body segments have ventral apodemes (Fig. 3). In Diplopoda and Pauropoda
these are the tracheal apodemes (see below). In Symphyla there are no tracheae
connected with the apodemes – the tracheae may be secondarily reduced like in
most Pauropoda.
11. Trichobothria basally swollen. Trichobothria are a special type of sensory hairs
which are set in a complicated socket. Trichobothria occur in numerous groups of
terrestrial arthropods (especially in arachnids, but unfortunately not in Chilopoda),
but in Progoneata the trichobothria are characterised by having the base of the hair
swollen (Fig. 4). In Symphyla there is one such pair of trichobothria in the posterior
end of the body (RFB: fig. 20-7D, p. 710). In Pauropoda there are five pairs
laterally on the body (RFB: fig. 20-13, p. 718). In Diplopoda trichobothria are
known only from the Penicillata where there are 3 pairs on each side of the head. In
spite of the different body parts where the trichobothria are situated, the
characteristic structure of the progoneate trichobothria be regarded as apomorphic.
Within Progoneata, Symphyla are sister-group to Diplopoda + Pauropoda. Synapomorphies
between Diplopoda and Pauropoda include:
12. Immediately behind the mandibles there is a complex ‘lower lip’ (Fig. 5), the
composition of which is controversial. Some regard it as a composite of the two
pairs of maxillae, others maintain that it is formed exclusively by the first pair of
maxillae, the second pair being entirely suppressed; at least part of the dorsal part of
the second maxillary segment is represented by the ‘collum’ (RFB: fig. 20-9, p. 712,
fig. 20-13, p. 718). Cf. character 5 above.
13. In both groups, the spiracles are situated on the sterna, near the leg bases (RFB: fig.
20-10B, p. 713). Both groups have tracheal apodemes associated with the spiracles
(cf. character 10). Tracheae have arisen several times independently in arthropods.
The ventral system in Diplopoda + Pauropoda undoubtedly represents one
‘invention’ of tracheae, whereas it is more doubtful if the lateral system in non-
3
scutigeromorph centipedes (RFB: fig. 20-2E, p. 705) is homologous with that of
Diplopoda + Pauropoda. The tracheal system in Symphyla (RFB: fig. 20-7, p. 710)
is even more dubious in this respect. The dorsal tracheal system of scutigeromorph
centipedes (RFB: fig. 20-2B, p. 705) certainly represents an independent ‘invention’.
Based on the characters discussed above, the relationships of the myriapods can be
illustrated as in the cladogram, Fig. 6.
Alternative relationships between the myriapod classes have been suggested. Fig. 2 thus
suggests a sister-group relationship between Pauropoda and Chilopoda, based exclusively
on the morphology of spermatozoa; this similarity is probably a symplesiomorphy.
Symphyla + Chilopoda have also been regarded as sister-groups, mainly because both
classes lack limbs on the last two body segments. Balanced against the autapomorphies for
Progoneata suggested above, this character is, however, not convincing.
4
CLASS CHILOPODA – CENTIPEDES (DA.: SKOLOPENDRE)
RFB: 703-710.
The numbers of apomorphies in this section refer to Fig. 7.
Chilopoda autapomorphies:
1. First pair of body limbs transformed into poisons fangs (‘forcipules) (RFB: fig. 202, A, C, p. 705).
2. Second maxilla in the embryo provided with an ‘egg-tooth’.
3. Nucleus of spermatozoon spiral-shaped
Systematic review of Chilopoda – centipedes
More than 3000 species of centipedes have been described. Thirty-two species have been
recorded in Denmark.
Order Scutigeromorpha
Ca. 130 species from the warmer parts of all continents. Easy to recognize by the 15 pairs
of extremely long, multi-segmented legs, and equally extremely long antennae. Composite
eyes which may be inherited from the common ancestor of all centipedes although some
structural details suggest that the eyes of scutigeromorphs may be derived from single eyes
of the type found in Lithobiomorpha and Scolopendromorpha; in the latter case the
secondarily composite eye in Scutigeromorpha is an autapomorphy. Certain
autapomorphies include:
16. The dorsal spiracles (RFB: fig. 20-2B, p.705)
17. The strongly sub-segmented tarsi
Scutigera coleoptrata is common in southern Europe and has been found occasionally in
houses in Denmark (introduced).
Order Lithobiomorpha
Ca. 1500 species from all parts of the World. Fifteen pairs of walking legs like in
Scutigeromorpha, but the tarsi are not multi-segmented, and the eyes are not composite; the
spiracles are lateral and are present only on some of the segments. An autapomorphy is:
18. The single testicle (RFB: fig. 20-4, p. 707). Two testicles are formed in the embryo,
but one is later reduced. (Scutigeromorpha have paired testicles; see below on
Scolopendromorpha and Geophilomorpha, character 12).
A further, possible autapomorphy is:
5
19. coxal pores (Fig. 8, cf. also below) on at least two pairs of legs, not only on the last
pair as in Scolopendromorpha and Geophilomorpha.
Lithobius forficatus (to 3 cm long) is extremely common in Denmark, like several smaller
species of the same genus. Lamyctes emarginatus is the only myriapod known from
Greenland; it is parthenogenetic and is also known from Denmark.
Order Craterostigmomorpha
Only one species, Craterostigmus tasmanianus, from Tasmania and New Zealand. Hatches
from the egg with 12 pairs of legs, the adult number of 15 pairs is reached after one moult;
the number of leg-pairs is certainly a symplesiomorpy with the two orders above. C.
tasmanianus superficially resembles a Lithobious.
Order Scolopendromorpha
Ca. 500 species in all parts of the World, mainly in warm regions. They resemble
Lithobiomorpha superficially, but they have 21 or 23 pairs of walking legs. An
autapomorphy is:
20. The tergum of the poison fang segment is fused with that of the following segments
(that carrying the first pair of walking legs). (The fused tergum is seen in RFB: fig.
20-1A, p. 704 as a trapezoid plate just behind the head).
Family Scolopendridae: four eyes on each side of the head. The very large centipedes
belong here, genus Scolopendra and others in the tropics and subtropica including southern
Europe.
Fam. Cryptopsidae: no eyes. Cryptops hortensis (2-3 cm) in Denmark. Scolopocryptops (=
Otocryptops).
Order Geophilomorpha – Da: jordskolopendre
Ca. 1000 speices in all parts of the World. From 29 to almost 200 pairs of legs. No eyes.
Good autapomorphies include:
21. the earthworm-like burrowing technique (RFB: 707)
22. the constant number of 14 antennal articles. In the other orders, the number is large and
variable.
The high number of legs and the lack of eyes are other possible autapomorphies.
6
Several families, a dozen species in Denmark including Geophilus carpophagus, which is
bioluminescent (glows in the dark) and occurs in old houses, and Strigamia maritima,
which is sometimes abundant under seaweed on the beach.
Centipede phylogeny
The phylogeny of centipedes has been subject of much debate. The discussion illustrates
very well the difficulties with deciding which characters are original, plesiomorphic, and
which are derived, apomorphic. The Geophilomorpha have been regarded as sister-group to
the other centipede orders, and so have the Scutigeromorpha. The class has also been
divided into two groups: Anamorpha (= Scutigeromorpha + Lithobiomorpha) and
Epimorpha (= Scolopendromorpha + Geophilomorpha). Based, among other things, on
increased knowledge of the fifth order, Craterostigmomorpha, Dohle (1985) and Shear &
Bonamo (1988) were able to present a convincing phylogenetic analysis, according to which
relationships are as shown in Fig. 7.
The group Anamorpha was named after the mode of postembryonic development in its
members, viz., hemianamorphosis: The juveniles hatched from the egg have 4 pairs of legs
(excluding the poison fangs) in Scutigeromorpha, 6-7 pairs in Lithobiomorpha. The adult
number (15 pairs) is gradually attained during growth, and when it has been reached, no
new leg-pairs are added during succeeding moults. Hemianamorphosis occurs in all
Pauropoda and Symphyla and also in primitive Diplopoda; this character is thus a clear
symplesiomorphy for the members of ‘Anamorpha’.
Several synapomorphies are shared by Lithobiomorpha,
Scolopendromorpha and Geophilomorpha, including:
Craterostigmomorpha,
4. the head is flattened
5. the tentorium is reduced in a characteristic way
6. the sternum and coxae of the poison fangs are fused to a coxosternum (RFB: fig.
20-2, p. 705, “coxosternite plate of forcipule”). This is clearly apomorphic, since
the poison fangs are derived from normal walking legs
7. the last leg-pair at least has coxal organs of a characteristic structure. They open to
the surface through coxal pores (Fig. 8) and probably serve a water-regulatory
function
8. the spermatophore is placed on a web produced by a spinneret in the rear end of the
male (RFB: fig. 20-6A p. 709).
Craterostigmomorpha,
synapomorphies:
Scolopendromorpha
og
Geophilomorpha
share
further
9. eggs and young juveniles are protected by parents (RFB: fig. 20-6C, p. 709)
10. juveniles hatch with the full (or almost full) adult number of segments and legs.
Scolopendromorpha og Geophilomorpha finally share the following synapomorphies:
7
11. juveniles hatch with full number of adult number of segments and legs
12. the testicles are fusiform, with vasa efferentia originating from both ends (Fig. 9, cf.
RFB: fig. 20-4, p. 707)
13. tracheae from different segments anastomose
14. there is no median suture on the coxosternum (cf. character 6)
15. there is a direct articulation between first and fourth article of the poison fang’s
telopodite (Fig. 10, cf. RFB: fig. 20-2C, p. 705).
One character is in strong conflict with the cladogram, Fig. 7, viz., the heterotergy. In
Geophilomorpha all terga are of similar size (homotergy). In the other orders there is a more
or less pronounced alteration between short and long terga: heterotergy. In RFB: fig. 20-1, p.
704, the heterotergy is clearly seen in Lithobius, not so clearly in Otocryptops. In Scutigera
the short terga are entirely hidden under the long ones. Intuitively one would believe
homotergy to be original, heterotergy thus being a synapomorphy for all centipedes except
Geophilomorpha. Balanced against characters 4-15 above, the heterotergy, however, must
be regarded as convergent or plesiomorphic, in the latter case the homotergy in
Geophilomorpha would be secondary.
Spermatological evidence (Jamieson 1987) is also partly in contrast with the phylogeny
advocated above. Spermatology does support the sister-group relationship between
Scutigeromorpha and the rest, but also provides a possible (but not very well founded)
synapomorphy between Lithobiomorpha and Geophilomorpha, which is in conflict with
characters 11-15 above.
8
CLASS SYMPHYLA – SYMPHYLIDS, DA.: SYMFYLER
RFB: 710-711.
The large spinnerets in the posterior end may constitute an autapomorphy for symphylids. It
is, however, uncertain, whether the spinnerets are homologous with the cerci of Hexapoda
(the cerci of some Diplura have spinning glands like the spinnerets of Symphyla). The
position of the two trichobothria is another possible autapomorphy (but not the trichobothria
by themselves, see character 18 in the chapter "The possible monophyly of Myriapoda and
the relationships between the myriapod classes"). Also, the extra tergites may constitute a
symphylidan autapomorphy although their number is variable.
The styli mentioned by RFB (p. 711) (Fig. 11) also occur in some apterygote hexapods:
Archaeognatha and Diplura. Also, stylus-like structures are found in the diplopod subclass
Penicillata, and in Pauropoda.
About 160 species of Symphyla have been described. Four species have been found in
Denmark. Scutigerella immaculata – one of the largest symphylids – is very common in
humid forest soil and similar places in Denmark.
9
CLASS DIPLOPODA – MILLIPEDES, DA.: TUSINDBEN
RFB: 711-717.
The numbers of apomorphies in this chapter refer to Fig. 12.
Good autapomorphies for millipedes are:
4. diplosegments (RFB: 713).
5. spermatozoa without a flagellum (Fig. 2)
6. antennae with 8 articles, with four large, cone-shaped sense organs on the tip (Fig.
13)
There are 16 orders of millipedes in the current classification, a clear example of
‘taxonomic inflation’. Looking at the degree of distinctiveness and recognisability it is
rather the superorders of millipedes that may be compared with insect of arachnid orders.
About 10,000 species of millipedes have been described; 42 species are known from
Denmark.
SUBCLASS PENICILLATA – pincushion millipedes, da.: penseltusindben
easily recognized by the autapomorphic character:
12. tufts of bristles along the sides of the body and in the posterior end
About 100 described species from all regions. Only a few mm long, the pincushion
millipedes exhibit many primitive traits and seem not to have departed very much from the
millipede ground-plan. They thus have retained trichobothria (cf. character 18 in the section
on myriapod relationships), their cuticle is not calcified, and the number of legs is relatively
low: 11-17 pairs in adults. Terga, pleura and sterna are independent (except that the terga
are fused into twos [diplosegments]). No legs are modified for copulation. Sperm transfer
happens indirectly: the male deposit spermatophores which are later taken in by the female
(RFB: fig. 20-12E, p. 717).
It has recently been suggested (Kraus & Brauckmann 2003) that the Penicillata are closely
related to the extinct Arthropleurida, giant (more than 1m, perhaps even more than 2m)
myriapods from the Devonian, Carboniferous and Permian periods.
One order, Polyxenida. One species in Denmark, Polyxenus lagurus. See RFB: fig. 20-8B,
p. 712. P. lagurus is often, but not always parthenogenetic, and it is this species which RFB
(p. 717) refers to.
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SUBCLASS CHILOGNATHA
Superorder Pentazonia
Good autapomorphies:
13. the last pair of legs (and sometimes also the penultimate and antepenultimate pairs)
of the male are modified into clasping organs which hold the female during
copulation
14. the sterna are divided in the midline
Pentazonia are also characterized by a relatively low number of legs: 17-37 pairs in adults.
Terga, pleura and sterna are independent. The group includes 3 orders and a total of ca.
350 described species from all parts of the World. One species in Denmark.
Order Glomeridesmida. Unlike other Pentazonia, glomeridesmidans cannot roll up into a
sphere. A few cm long. Occur in South and Central America , and in SE Asia.
Order Sphaerotheriida. Giant pill millipedes (da.: kæmpekugletusindben). Up to the size
of a golf ball when rolled up. Occur on the southern hemisphere except South America.
Order Glomerida. Pill millipedes (da.: kugletusindben). Rarely more than 7 mm in
diameter when rolled up. Occur on the northern hemisphere and SE Asia. One species,
Glomeris marginata, in Denmark (shown in RFB: fig. 20-8D, E, p. 712), common in
deciduous forest.
Superorder Colobognatha
Good autapomorphies:
15. mouthparts more or less modified into stiletto-like structures with unknown
function
16. first juvenile stadium hatching from the egg with four pairs of legs (three pairs in
other millipedes, see RFB: fig. 20-12F, p. 717)
17. a parent (the mother in some species, the father in others) protects the eggs by
rolling itself around them like in some centipedes (character 9 in the section on
centipedes).
The group includes four orders and a total of ca. 300 species, a few cm long, described
from all parts of the World.
Order Platydesmida. Mouthparts only moderately modified. Occur on the northern
hemisphere and SE Asia.
Order Polyzoniida. Mouthparts strongly modified. Eyes present. Occur in all parts of the
World. Polyzonium germanicum (Fig. 14) occurs in Denmark, but is rare.
11
Order Siphonocryptida. Very similar to preceding order. Four species from SE Asia, the
Canary Islands and Madeira.
Order Siphonophorida. Mouthparts stiletto-like (Fig.14). No eyes. Occur in North,
Central and South America, South Africa and Southeast Asia. The ruling World
Champion in leg numbers belongs here: Illacme plenipes from California (up to 750
legs).
Superorder Nematophora
The name means ‘thread-bearer’, and accordingly a good synapomorphy is:
18. posterior end with one or more pairs of spinnerets (Fig. 15)
In Nematophora, the sterna are not fused with the pleura. In this character, Nematophora
resembles the superorders mentioned above and differs from those treated further down.
The group includes three orders and a total of ca. 1000 described species. Three species
are known from Demmark.
Order Stemmiulida. One to two eyes on each side of the head. Body a few cm long,
circular in transverse section, tapering posteriorly. No defence glands, but some species
exhibit an incredible defensive behaviour, escaping from aggressors in long jumps. Occur
in South and Central America, tropical Africa and India.
Order Callipodida. Many eyes. Up to 10 cm long, cylindrical. Defence glands present
(smell horrible!). Occur in the warmer parts of the Holarctic region including the
Mediterranean region.
Order Chordeumatida. Many eyes (except in some species which are blind). Body a few
cm long, often moniliform or with flat ‘wings’ like Merocheta (see below). Occur in all
regions. The Danish Nematophora belong here, our commonest species is Craspedosoma
rawlinsi which occurs in humid forest soil.
Superorder Merocheta – flat-backed millipedes, da.: kiletusindben
Good autapomorphies:
19. number of segments almost constant: the vast majority of the species have 19-20
segments1 in the adult (other Helminthomorpha, cf. Fig. 12, have more segments,
and the number is often variable within each species).
20. no eyes (convergent with many subgroups within other superorders)
1
Traditionally, segments of millipedes are counted as follows: The four anteriormost segments, which are
not diplosegments, are each counted as one. The following segments, which are diplosegments, are also
counted as one each. The telson, which is not a segment, is also counted as one. A merochetan millipedes
with ’20 segments’ thus consists of the four anterior, simple segments, 15 diplosegments, and the telson
(4+15+1 = 20).
12
21. defence glands with two compartments, produce HCN (mentioned by RFB: 715),
this type of glands only occurs in Merocheta.
In most species of Merocheta the body rings (‘segments’) have a pair of keel- or winglike
dorsolateral outgrowths, giving the dorsal side a flattened appearance. Using the flat
back, the merochetans wedge their way between, e.g., fallen leaves on the ground (RFB:
“flat wedgers, p. 714).
Only one order:
Order Polydesmida. Ca. 3000 described species, from a few mm to ca.10 cm long,
occurring in all parts of the World. Ten species in Denmark, including several of the
genus Polydesmus (pictured without a name on RFB: fig. 20-8C, p. 712).
Superorder Juliformia – cylindrical millipedes, da.: cylindertusindben
Good autapomorphies:
22. the first body segments, collum, overlaps the posterior part of the head as well as
the anterior part of segment 2 (RFB: fig. 20-8F, p. 712)
23. Spermatozoa with a “bilayered acrosome” (Fig. 2). (A “bilayered acrosome” also
occurs in Hexapoda, and loss of one of the ‘layers’, the actin-containing
perforatorium, is considered a possible autapomorphy of Myriapoda [char. 8 in
the chapter on myriapod relationships]. In Juliformia, a perforatorium ‘reappears’, but it lacks actin, is called a pseudoperforatorium and is regarded as a
novelty ‘invented’ by the common ancestor of Juliformia).
Juliformia constitute the millipedes as typically understood by laymen: long, cylindrical
animals with plenty of legs (although the highest numbers of legs occur in
colobognathans, cf. above). The defence glands of Juliformia produce benzoquinones – a
type of defensive chemical which is widely distributed among arthropods.
The group includes three orders with ca. 4000 described species, 27 species in Denmark.
The orders can only be told apart by details in mouthparts and gonopods.
Order Spirobolida. From a few to more than 20 cm long. Do not occur naturally in
Europe, but in all other parts of the World. The genus Narceus, mentioned by RFB,
belongs here. A small species has been introduced to the greenhouses of the Botanical
Garden in Copenhagen where it seems to thrive.
Order Spirostreptida. From a few to 30 cm long. Distributed in the same areas as
Spirobolida. The very large Archispirostreptus gigas from East Africa, which is one of
the most frequent ‘terrarium millipedes’, belongs here. Some species are pests on
peanuts, potatoes etc. in Africa.
Order Julida. Occur naturally only on the northern hemisphere. Rarely longer than 5 cm.
Many common Danish species belong here, including the black Julus scandinavius, the
13
brown species of Cylindroiulus, and our largest millipede: Ommatoiulus sabulosus (up to
5 cm, with two yellow longitudinal stripes). Some species, especially the small, thin
Blaniulus guttulatus, may be pests on potatoes and sugar beets.
-o0o-
The 16th millipede order, Siphoniulida, is known only from a handful of specimens. It is
probably related to Colobognatha or Juliformia.
Millipede phylogeny
Enghoff (1984) presented a cladistic analysis of the millipede orders 2. The results are
shown in the cladogram, Fig. 12 (and in RFB: p. 716). Numbering of characters in the
present chapter follows Fig. 12.
Since 1984, a number of studies on millipede phylogeny have been published, including
some using molecular characters. So far, however, the results have not stabilized, and the
1984 model is offered here as, so far, the most robust one.
The class Diplopoda consists of two subclasses: Penicillata, which was characterized
above, and Chilognatha (not to be confused with Chilopoda) which is characterized by
the following autapomorphies:
4. cuticle calcified
5. most diplosegments with a pair of defence glands (not more than one pair,
although RFB 813 suggests the opposite); the glands are secondarily missing in,
e.g., Chordeumatida.
6. no trichobothria (cf. character 16 in the chapter on myriapod relationships)
7. certain muscles and ligaments reduced (in contrast to Penicillata to Penicilalta,
where they have been retained)
8. spermatozoa ‘depressed’, i.e., strongly shortened along the anterior-posterior axis
(Fig. 2)
Among the five superorders of Chilognatha, four (Colobognatha + Nematophora +
Merocheta + Juliformia = Helminthomorpha on Fig. 12) share an obvious synapomorphy,
viz.:
9. at least one leg-pair on segment 7 in the male is modified into gonopods which
serve as copulatory organs.
Nematophora, Merocheta and Juliformia (= ‘Eugnatha’ on Fig. 12) share further
synapomorphies, including:
2
The Siphonocryptida had not been recognised as a separate order in 1984 but uncontroversially belong in
Colobognatha.
14
10. terga and pleura fused into pleuroterga (this fusion has, however, happened
convergently in the colobognathan order Platydesmida)
Merocheta and Juliformia are sister-groups, united by the apomorphy:
11. pleuroterga and sterna fused into complete body rings (RFB: fig. 20-10C, p. 713).
Merocheta and Juliformia are sometimes collectively referred to as ‘ring-forming
millipedes’.
On Fig. 2, Polyzoniida branch off before Glomerida. This is in conflict with the 'strong'
character 9, and the spermatological evidence on which this part of Fig. 2 is based is
accordingly dubious.
15
CLASS PAUROPODA – PAUROPODS, DA.: PAUROPODER
RFB: 718.
The branched antennae constitute a good autapomorphy for pauropods. The pauropods
pictured by RFB belongs to the Tetramerocerata and almost has diplosegments like a
diplopod (6 terga for 9 pairs of legs); in Hexamerocerata the number of terga corresponds to
the number of legs.
About 500 species of Pauropoda have been described, and one or two handfuls of species
are known from Denmark.
Order Hexamerocerata. Many primitive traits are preserved, including tracheae on the first
body segment and powerful mandibles. Seven species from Africa and South America.
Order Tetramerocerata. No tracheae, mandibles reduced, weak, number of terga less than
number of leg-pairs. In all parts of the World.
16
IDENTIFICATION KEY TO MYRIAPODA
Classes/orders occurring in Denmark are shown with CAPITAL LETTERS. Orders not
occurring in Europe are in (brackets).
Key to the myriapod classes
1.
Most body segments with two pairs of legs. Usually calcified,
slow animals
One pair of legs per segment
MILLIPEDES, DIPLOPODA
2
-
Usually more than 1 cm long, brownish/yellowish. A pair of
poison fangs behind/below the head
Smaller than 1 cm, usually whitish. No poison fangs
CENTIPEDES, CHILOPODA
3
3.
-
Antennae moniliform, unbranched. Twelve pairs of legs
Antennae branched. Nine, rarely 10-11 pairs of legs
2.
SYMPHYLA
PAUROPODA
Key to the orders of centipedes, CHILOPODA
1.
-
15 pairs of legs
21 or more pairs of legs
2.
Antennae and legs extraordinarily long. Big, composite eyes. Spiracles
mid-dorsally
Antennae and legs ’normal’. A small group of single eyes on each side
of the head, or eyes missing. Spiracles lateral
-
3.
-
Large gland openings on coxae of the 2-4 posteriormost leg-pairs.
Body relatively compact
No coxal pores on posterior legs. Body relatively slender
4.
-
21, rarely 23 pairs of legs
29 or more pairs of legs
2
4
Scutigeromorpha
3
LITHOBIOMORPHA
(Craterostigmomorpha)
SCOLOPENDROMORPHA
GEOPHILOMORPHA
17
Key to the orders of millipedes, DIPLOPODA
(exluding Siphoniulida)
1.
2.
-
Characteristic tufts of setae (’brushes’) along the sides of the body. Rarely more
than 5 mm long
No such brushes. Often larger
At most 13 segments including telson. Body can be rolled into a sphere
Adults with more than 17 segments including telson. Body almost never capable
of rolling up into a sphere
POLYXENIDA
2
3
4
3.
-
13 segments incl. telson. Ball usually >1 cm in diameter
11-12 segments incl. telson. Ball (almost always) <1 cm in diameter
(Sphaerotheriida)
GLOMERIDA
4.
19-20 segments (exceptionally 18 or up to 25). No eyes. Usually with
dorsolateral processes rendering the dorsal surface more or less flat. Complete
body rings (= tergum + pleura + sternum)
Adults (almost always) with > 20 segments
POLYDESMIDA
5
5.
-
6.
7.
-
8.
-
9.
10.
-
Collum covering the posterior part of the head and the anterior part of segment 2.
Body circular in transverse section. Complete body rings (tergum + pleura +
sternum)
Collum smaller, and/or body transverse section not circular. Sternum, sometimes
even pleura, independent sclerites
Head with a longitudinal suture starting from anterior margin. Gnathochilarium
with a very large mentum
Head without such a suture. Gnathochilarium different
Lateral sclerites of gnathochilarium (stipites) meet in midline. Usualy a few cm
long, segments often hairy
Gnathochilarial stipites divided by mentum. Usually large animals (> 5 cm).
Body hairless
Collum small, head largely uncovered. Head/mouthparts not attenuated. Eyes
usually well-developed. Posterior end with spinnerets (may be difficult to see)
Anterior end different. Head/mouthparts usually more or less attenuated. At most
a few single eyes, often no eyes at all. No spinnerets
At most 32 segments. Body transverse section circular or with dorsolateral
projections.
Adults with >32 segments
Body transverse section semicircular, or depressed semicircular
Body with large or smaller dorsolateral processes
12.
-
No eyes. Head/mouthparts not attenuate
A few single eyes. Head/mouthparts attenuate
8
(Spirobolida)
7
JULIDA
(Spirostreptida)
9
11
CHORDEUMATIDA
10
Up to 10 cm long, eyes well-developed, strongly sculptured segments and often a
horrible smell
A few cm long, 0-2 single eyes on each side. Weakly sculptures segments, no
particular smell. Some species can jump
11.
-
6
Callipodida
(Stemmiulida)
12
14
(Glomeridesmida)
13
18
13.
-
With a mid-dorsal suture
No mid-dorsal suture
Siphonocryptida
POLYZONIIDA
14.
Tergum and pleura of each segment fused. Head/mouthparts only slightly
attenuate
Pleura separate from tergum. Head/mouthparts often extremely attenuate
Platydesmida
(Siphonophorida)
-
19
REFERENCES
(only those cited in the compendium)
Baccetti, B., Burrini, G., Dallai, R. & Pallini, V. 1979: Recent work in myriapod spermatology (The spermatozoon of Arthropoda XXXI). - Side 97-111 i Camatini, M. (red.): Myriapod biology. - Academic Press London
etc.
Deuve, T (ed.). 2000: Origin of Hexapods - Mémoires du Muséum national d'Histoire Naturelle (under
trykning).
Dohle, W. 1980: Sind die Myriapoden eine monophyletische Gruppe? Eine Diskussion der
Verwandtschaftsbeziehungen der Antennaten. - Abhandlungen des naturwissenschaftlichen Vereins in
Hamburg (NF) 23: 45-104.
Dohle, W. 1985: Phylogenetic pathways in the Chilopoda. - Bijdragen tot de Dierkunde 55(l): 55-66.
Enghoff, H. 1984: Phylogeny of millipedes - a cladistic analysis. - Zeitschrift für zoologische Systematik und
Evolutionsforschung 22: 8-26.
Jamieson, B.G.M. 1987: The ultrastructure and phylogeny of insect spermatozoa. - Cambridge University
Press, Cambridge etc.
Kraus, O. & Brauckmann, C. 2003: Fossil giants and surviving dwarfs. Arthropleurida and Pselaphognatha
(Atelocerata, Diplopoda): characters, phylogenetic relationships and construction. – Verhandlungen des
naturwissenshcaftlichen Vereins Hamburg, Neue Folge 40: 5-50.
Shear, W.A. & Bonamo, P.M. 1988: Devonobiomorpha, a new order of centipeds (Chilopoda) from the Middle
Devonian of Gilboa, New York State, USA, and the phylogeny of centiped orders. - American Museum
Novitates 2927: 1-30.
Wheeler, W.C., Cartwright, P. & Hayashi, C.Y. 1993: Arthropod phylogeny: a combined approach. - Cladistics
9: 1-39.
20
LEGENDS TO ILLUSTRATIONS
Fig. 1. The anterior tentorium is an internal skeletal structure which can be viewed as an
inward extension of the external surface of the head capsule. The upper scanning electron
micrograph shows the the head capsule of a millipede in ventral view; the paired tentoria
are aritculated laterally ("tilledningssted"). The lower SEM shows the same head capsule
in oblique posterior view. The circular hole in the head capsule is the articulation site of
the left antenna. Also notice the tridentate labrum which is characteristic of millipedes.
Fig. 2. Spermatozoan structure in myriapods, after Baccetti & al. (1979). Notice that the
branching pattern of the spermatozoan-based cladogram differs from the cladogram
recommended in the compendium text (Figs. 6 and 12).
Fig. 3. Sterna, spiracles and tracheal apodemes in millipedes. The upper SEM shows the
oval sternum in a species of Juliformia. On both sides, sternum is fused with pleura, the
latter hide the tracheal apodemes from view. (In Juliformia the two sterna of each
diplosegments are fused but the picture only shows the anterior sternum). The lower SEM
shows an isolated sternum of a species of Nematophora. Here the tracheal apodemes are
visible; you can perhaps imagine that they project 'into the paper', i.e. into the body.
Fig. 4. Trichobothria in a symphylid (left), a pauropod (center) and a pincushion
millipede (right). Notice the swollen basis of the trichobothria which are located in a
concavity in the cuticle. Of the remaining part of the trichobothria, only the tips are
shown.
Fig. 5. Gnathochilarium in a pauropod (left) and a pill millipede (right). Embryos above,
fully developed animals below.
Fig. 6.Suggested relationships within Uniramia (presuming that Uniramia is
monophyletic!)
Fig. 7. Relationships within Chilopoda according to Dohle (1985). Numbers refer to
synapomorphies mentioned in the text.
Fig. 8. Posterior end of a lithobiomorph centipede. Notice the coxal pores.
21
Fig. 9. Male gonads in Chilopoda Epimorpha. Geophilomorpha left, Scolopendromorpha
right.
Fig. 10. Poison fangs in Geophilomorpha. Notice the undivided coxosternum (cxs) and
the direct articulation between the first and the fourth telopodite article (arrow).
Fig. 11. Leg of a symphylid. Notice stylus (arrow).
Fig. 12. Relationships within Diplopoda. Modified after Enghoff (1984). Numbers refer
to synapomorphies mentioned in the text.
Fig. 13. SEM of antennal tip of a millipede. Notice the four large sense organs
(autapomorphy for Diplopoda).
Fig. 14. Millipedes of the superorder Colobognatha. a-c: Polyzonium germanicum, the
only Danish colobognathan. d: a species of the order Siphonophorida. e: anterior end of
another species of Siphonophorida; notice the extremely pointed head and the stout
antennae.
Fig. 15. A: Craspedosoma rawlinsi, the commonest Danish species of Diplopoda
Nematophora. B: posterior end of a species of Nematophora; notice spinnerets (arrow).
Fig. 16. The fossil millipede group Arthropleurida lived in the Devonian, Carboniferous
and Permian periods. From Kraus & Brauckmann (2003).
22