Chordeumatida - an overview | ScienceDirect Topics (2023)

Chordeumatida and Polydesmida, with troglobites in Europe, North America, and Japan;

From: Encyclopedia of Insects (Second Edition), 2009

Related terms:

  • Cladistics
  • Chemical Defense
  • Julida
  • Spirostreptida
  • Polydesmida
  • Polyxenida
  • Sphaerotheriida
  • Glomerida
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Alessandro Minelli, Sergei I. Golovatch, in Reference Module in Life Sciences, 2023

Habitats and Adaptations


At least five morphological body plans and a few life-forms can be distinguished among millipedes (Golovatch and Kime, 2009). The pin-cushion millipedes (ie, the representatives of the worldwide distributed order Polyxenida) are soft bodied, very small (usually <5mm long), extremely bristly, swift, and capable of withstanding much drier conditions than most other Diplopoda. Many polyxenidans live under loose tree bark or are characteristic inhabitants of microcaverns and small crevices under stones, in the uppermost soil, in litter, and in similar substrates.

The pill millipedes (the largely Holarctic order Glomerida and the Afrotropical and Indo-Australian order Sphaerotheriida) are collectively termed “rollers” because of their ability to roll themselves into mostly glossy balls. Pill millipedes are generally litter dwellers, but some smaller Glomerida are either troglobionts or geobionts.

The colobognathans (ie, the “sucking millipedes” with reduced mouthparts) and some Chordeumatida, which mostly possess flexible, worm-like, strongly tapered bodies, and shorter legs, are termed “borers.”

Many Polydesmida and numerous Chordeumatida, often conspicuously ornamented and relatively shorter, long-legged, and displaying more or less strong paranota (wing-like dorsolateral projections of the diplosegments), are referred to as “wedge types” and are characteristic of forest litter.

The lifestyle, or ecomorphological type, most common and widespread among Diplopoda is that of “bulldozers” or “rammers.” Their long, cylindrical, hard body with numerous diplosegments (hence, numerous pushing legs) penetrates the substrate like a bulldozer, using the broad head as a ram. Most juliform millipedes (Julida, Spirobolida, Spirostreptida, Callipodida, and some others) belong to this ecological type. This burrowing habit must have been critical in ensuring diplopods much or even most of their present-day high ecological and geographical performance. In particular, unlike the remaining ecomorphotypes, only juliforms, among Diplopoda, appear to have colonized virtually any suitable habitat. In fact, in Juliformia belong the few littoral dwellers and deserticoles, but this body plan also provides most of millipede diversity in troglobionts and geobionts, in addition to anthropochores. Indeed, the northernmost record of a millipede belongs to the subcorticolous European species Proteroiulus fuscus (Julida) in the forest–tundra belt of Yamal Peninsula, Russia׳s north, whereas perhaps the most characteristic deserticole among millipedes is Orthoporus ornatus (Spirostreptida) in the southern United States and adjacent parts of Mexico. Both these species are rare except in their native environments (Golovatch and Kime, 2009).

There are sound reasons to believe that, due to their capability to escape adverse conditions by burrowing in the soil, rotten logs, and similar shelters, juliforms (namely, species of the order Julida) dominate in Europe. This youngest, fully migratory nucleus of the millipede fauna shows a clear-cut inclination to dwell on open terrain. In contrast, all the remaining millipede orders display very evident geographical trends in diversification. In Europe, even the relatively uniformly distributed Polydesmida have a remarkable center of secondary diversification in Slovenia, whereas the Chordeumatida are particularly species-rich within the Atlantic climatic zone of western Europe (Kime and Golovatch, 2000; Golovatch and Kime, 2009). Furthermore, only a few species of Julida, apparently in response to the strongly adverse conditions that existed in Europe during the Ice Age, appear to have developed a reproductive strategy unique among terrestrial animals – the periodomorphosis, ie, as previously mentioned, the extension of male life by means of intercalary stadia.

Most millipede lineages are currently in a phase of rapid evolution and speciation; however, there are a few apparently relict groups (Hoffman, 1980). Polydesmida seem remarkably diverse largely due to their wedge type of burrowing allowing ecological niche partitioning mainly in the litter and at the soil–litter interface. This is particularly obvious in tropical and subtropical faunas. However, examples of troglobionts, geobionts, and myrmecophilous as well as arboricolous species are about as numerous among Polydesmida as among juliforms, whose type of burrowing and lifestyle seem the most characteristic, widespread, and ecologically progressive among all recent Diplopoda. It is forest litter that seems to have always been and still remains the main and primary environment for millipedes (Kime and Golovatch, 2000; Golovatch and Kime, 2009).

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Subphylum Myriapoda, Class Diplopoda

Jean-Jacques Geoffroy, in Thorp and Covich's Freshwater Invertebrates (Fourth Edition), 2015

Ecology and Behavior of Freshwater Millipedes

Physiological Problems Faced by Millipedes in Freshwater

As a first look and rough answer, we could consider that there are no “truly aquatic” millipedes anywhere in the world because all millipedes lack a gill or other structure to extract oxygen from water, unlike almost all other aquatic organisms. Their respiratory system is specially adapted for extracting oxygen from air. The exchange of oxygen and carbon dioxide between the cells of these arthropods and the atmosphere takes place via tracheae. The tracheal respiratory system opens via cuticular spiracles located on sternites (Blower, 1985; Hopkin and Read, 1992). Being air-breathing, most millipedes living in flooded or waterlogged soils usually come to the surface, move to upper litter layers, or even climb trees to avoid drowning.

The excretory system of millipedes is also not adapted for life in water. Terrestrial millipedes primarily excrete nitrogenous wastes as ammonia (which has to be excreted rapidly as gas) and uric acid (which is stored before excretion), with the latter requiring more energy but less water to produce and excrete. They have not evolved to release nitrogenous excretory products directly into water as liquid ammonia.

Nevertheless, some millipedes can survive under water for surprising lengths of time. Most of them belong to the order Polydesmida (Figure 26.4), like the pantropical Oxidus gracilis (C.L. Koch, 1847). These millipedes may rely on an air bubble that gets trapped around their spiracles, as in some diving beetles. Once the oxygen in that air bubble is depleted, however, the diplopod must replenish it with more air, or drown. Such a special situation among the terrestrial millipedes was reported about polydesmid millipedes (Figure 26.5) under stones in French streams and tentatively explained a century ago as a form of branchial respiratory system in millipedes. Observations of the diplopods making pumping movements of the rectal area were interpreted as a respiratory surface formed by the rectal wall (Causard, 1903).

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FIGURE 26.4. Oxidus gracilis (Diplopoda, Polydesmida, Paradoxosomatidae; C.L. Koch, 1847).

A pantropical widespread millipede.

Photo Lemaire, J.-M.

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FIGURE 26.5. Polydesmus angustus (Diplopoda, Polydesmida, Polydesmidae; Latzel, 1884).

A common saprophagus polydesmid millipede from Western Europe, shown here walking on oak litter.

Photograph by Régine Vignes-Lebbe and Geofffroy, J.-J.

Several cases of such aquatic or semiaquatic diplopods have been documented in different localities, ecosystems, and biogeographical regions in the world. Examples are reported for species in Polyzoniida, Julida, Chordeumatida, and above all, Polydesmida.

Millipedes of Tropical Islands and Amazonian Floodplains

The widespread pantropical polydesmid Aporodesminus wallacei Silvestri, 1904 (Pyrgodesmidae) is distributed in several islands (St. Helena, Hawaii, Tahiti) and in urban freshwater creeks near Sydney, Australia (see below). It belongs to a group of minute polydesmid millipedes (Figure 26.6), some of them well adapted to survive long submersions. Adults and subadults have been sampled underwater, and the species is considered to be semi-aquatic millipedes, with similar habits to the related minute pyrgodesmid Cryptocorypha ornata (Attems, 1938). The aquatic habit in these taxa is supported by the well-adapted structure of the mouthparts and the presence of a cerotegument enabling plastron respiration (Adis etal., 1998). Morphological adaptations of the mouthparts and spiracles have been reported in diplopods strongly suspected of entering freshwater bodies and feeding on fine-grained organic particles in the water (Enghoff, 1985; Burrows etal., 1994). In most of these species, submersion tolerance or resistance lasting weeks or even months is possible because of plastron respiration using very special structures and cuticular secretions, including a cerotegument that covers the spiracles (Messner and Adis, 1992, 1994, 1997; Messner etal., 1996). This is particularly well documented in another pyrgodesmid diplopod, Myrmecodesmus adisi (Hoffman, 1985), which was reported to have survived more than a 6-month long flood period under a submerged tree trunk in an Amazonian inundation forest (Hoffman, 1985; Adis, 1986; Messner and Adis, 1988; Adis and Messner, 1997). All tergites are covered with this thick cerotegument layer, extending to the coxal region of the sternite. The spiracles are, therefore, entirely or partly covered by the externally hydrophilous secretion that facilitates long-term submersion. Air is held in the hydrophobic cavity below the cerotegument and around the spiracles. Then, plastron respiration adds oxygen from the surrounding water to the trapped reserve of air; bubbles of atmospheric air are also captured in the water and added to the plastron (Adis, 1992; Messner and Adis, 1992, 1994, 1997). However, all field observations and laboratory experiments are related to adults or subadults, and development of juveniles probably remains restricted to very moist terrestrial habitats and banks of water bodies (Adis etal., 1998). In contrast, other species, such as Myrmecodesmus duodecimlobatus (Golovatch, 1996), lacking either morphological or physiological adaptations, rely on vertical migrations along tree trunks to survive flood periods (Adis etal., 1996; Adis, 1997; Minelli and Golovatch, 2001; Adis and Junk, 2002).

Chordeumatida - an overview | ScienceDirect Topics (3)

FIGURE 26.6. Diplopoda, Polydesmida, Pyrgodesmidae. Habitus of a minute pyrgodesmid millipede from Vanuatu.

Photograph by Deharveng, L.

Although almost nothing is known about the small chelodesmid Pandirodesmus disparipes Silvestri, 1932 from Guyana, it is suspected of being semi-aquatic. It is good climber, swimmer, and glider, and several morphological features of the legs, tubiform spiracles, sternites, and hydrophobe setae strongly suggest a special ecology closely associated with freshwater, despite the absence of cerotegument and microtrichia in the spiracles (Golovatch and Kime, 2009).

Millipedes of Swamps and Rivers

Several reports of “aquatic” Polydesmida (mainly Paradoxosomatidae) were recently noted for streams in North America (Shelley, personal communication). Numerous specimens, thousands of them, were observed in the middle of a stream, covering water algae; all were alive and well as far as it could be determined. These polydesmid millipedes are sightless, and their mass migrations seem not to be deterred by crossing a stream. They cannot be considered as a truly aquatic species of millipedes, but they certainly seem to show capacity to survive in water. Paradoxosomatid species observed in the Hudson Valley were under wet soggy leaf litter all along a very small headwater stream. They are not “aquatic” but living and well adapted to damp areas close to the streams. Similar situations have been observed in Australia, and they are thought to have occurred in swamps, floodplains, and river banks in Central Europe during major floods last century (Tajovsky, 1999). European millipedes can survive in floodplains using a risk-strategy, due to a combination of high reproductive rates, dispersal, and re-immigration following catastrophic events (Adis and Junk, 2002; Golovatch and Kime, 2009).

Aquatic Australian Millipedes

Populations of two millipede species were discovered under stones submerged in a creek on the Macquarie University campus in the northern suburb of Sydney. One was a Polyzoniida belonging to the family Siphonotidae, and the second was a Polydesmida belonging to the family Pyrgodesmidae. The latter is closely related to pyrgodesmid species described in oceanic islands and Amazonian inundation forests. This was the first published report of “aquatic millipedes” in Australia. They became targets in the center of a hot debate about protection and conservation of invertebrate populations threatened by construction works of a dam (Burrows etal., 1994; Black, 1997). There was obvious risk of damage to the clay walls of the creek, where the millipedes were suspected to lay their eggs. Animals were present in numbers in and near the water from autumn to late spring, but moved to other habitats during the summer, probably burrowing into damp soil or the creek bed. They were observed leaving the water in large numbers during early winter to mate and lay eggs in cracks in the banks. They apparently breathe cutaneously, and both adult and juvenile stadia have been found totally submerged; long-term submergence is considered a normal part of their behavior (Burrows etal., 1994; Adis etal., 1998). The specimens were later identified as Aporodesminus wallacei Silvestri, 1904 (Pyrgodesmidae), and a well-documented re-description of the species was published (Adis etal., 1998). A. wallacei has also been reported from St. Helena (southern Atlantic Ocean), Tahiti, and the Hawaiian Islands. It is not known to be native anywhere in its range but belongs to the pyrgodesmid millipede fauna of Australia (Mesibov, 2012).

The modified mouthparts in A. wallacei exhibit hypertrophied, hair-shaped teeth of pectinate lamellae and reduced masticating parts (Adis etal., 1998: Figs 5-8), and the species show highly adapted features of the tegument allowing long-term resistance to water submersion (see discussion above on the cerotegument). Having both mouthparts adapted for food uptake underwater and a cerotegument for plastron respiration, A. wallacei is one of the best semiaquatic millipede examples we have, with the others distributed in deep caves.

Millipedes in Subterranean Habitats of Europe

Caves and subterranean habitats more generally are shelters for many different lineages of myriapods, particularly diplopods. Most of the cave-dwelling and strongly adapted troglobionts differ from their epigean relatives in showing striking morphological and physiological features (Shear, 1969; Mauriès, 1994, 2004; Culver and Shear, 2012). Among these adaptations to cave life, mouthparts are commonly convergently modified in Julidae, Blaniulidae, Polydesmidae, etc. in different geographic areas (Enghoff, 1985). The cave environment is sometimes considered equivalent ecologically to an island, and their insularity combined with general habitat conditions in subterranean environments appear to be highly significant components of millipede diversity and adaptation (Enghoff, 1993). Therefore, cave-dwelling millipedes are obviously adapted to hygrophily and most certainly comprise the best candidates to possess aquatic or at least semiaquatic ways of life among terrestrial myriapods.

Serradium semiaquaticum Enghoff etal., 1997 (Polydesmida, Polydesmidae) has been described from several northern Italian caves (Figure 26.7) and is a close, derived relative and sister species of Serradium hirsutipes Verhoeff, 1941, which lives in the same caves but shows a wider distribution (Enghoff etal., 1997). The species is utterly remarkable in exhibiting peculiar semiaquatic and feeding habits and modified anatomical features, especially mouthparts and spiracles (Caoduro, 1995; Enghoff etal., 1997; Adis etal., 1997, 1998). S. semiaquaticum appears to be the single truly semiaquatic millipede occurring in a cold subterranean environment, at least for subadults and adults (Adis etal., 1997; Golovatch and Kime, 2009). This troglobitic species is remarkable in showing a combination of morphological, ecophysiological, and ecoethological adaptative traits that facilitate its amphibious mode of life. These include the following:

Chordeumatida - an overview | ScienceDirect Topics (4)

FIGURE 26.7. Serradium semiaquaticum (Diplopoda, Polydesmida, Polydesmidae; Enghoff etal., 1997).

A cavernicolous millipede from northern Italian caves, which is remarkable because of its semiaquatic habits.

Photograph by Luca Cavallari.

The modified, broom-like hypertrophied pectinate lamellae of the mandibular gnathal lobes and reduced masticating parts, which allow uptake of fine organic particles, clay, and limestone material from moist surfaces along the banks of water bodies and from underwater and the bottom of cave rivulets.

A hydrophilic surface of the cuticle, which facilitates entry to the water.

Hydrophobic microtrichia of the spiracles, which allow plastron respiration under freshwater and small bubbles of atmospheric air in the water to be captured if water currents are strong enough.

An ion-catching chloride epithelia in the intersegmental membranes, which allows additional uptake of ions and of dissolved oxygen from the water.

This semiaquatic troglobiont is a stenothermal species that enters cold subterranean water bodies voluntarily as part of its natural semiaquatic behavior, which contrasts with the behavior of its relative S. hirsutipes. Taken together, the listed adaptations enable specimens to enter subterranean water bodies periodically during the day or and to remain submerged for up to four weeks in laboratory conditions; the former demonstrates the species’ tolerance and the latter its submersion resistance (Adis etal., 1997).

In Papua, New Guinea, the hygrophilous montane troglobite Selminosoma chapmani Hoffman, 1978 (Polydesmida, Paradoxosomitadae) is also highly adapted both to ecological conditions in caves in general and to total immersion in water in particular (Hoffman, 1977; Messner etal., 1996). Moreover, several other cases are strongly suspected from China or Southwest Asia where millipedes have been observed entering water without apparent difficulties (Deharveng and Bedos, 2000).

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Chemical Ecology

Konrad Dettner, in Comprehensive Natural Products II, 2010

4.09.25 Arthropoda: Myriapoda: Progoneata: Diplopoda (Millipedes) and Symphyla

Together with Pauropoda and Diplopoda, representatives of Symphyla comprise the taxon Progoneata. The soil-dwelling predatory Symphyla (160 species) resemble centipedes and possess large spinnerets at the posterior body parts. Upon molestation, ducts of spinning glands emit sticky threads, which may entangle the mouth parts of all kinds of aggressors.

Herbivorous to saprophagous millipedes, which comprise about 13000 species worldwide (probably 80000 Myriapoda), lack poisonous fangs and do not bite. Usually, they roll into a defensive ball or spiral, and many species emit highly toxic or foul-smelling compounds. With the exception of five orders Polyxenida, Sphaerotherida, Glomeridesmida, Chordeumatida, and Siphoniulida, representatives of the remaining sometimes even aposematically colored 10 Diplopoda taxa produce defensive secretion in serially arranged defensive glands.165,166

The basally arranged noncalcareous Polyxenida (Penicillata; bristle millipedes) lack defensive glands and instead project hooked bristles against attackers such as ants.12 Similar to modified larval hairs of dermestid beetles, predators are thus effectively entangled.

Among Pentazonia, which can coil into a sphere or ‘pill’, Sphaerotherida and Glomeridesmida lack defensive glands, whereas Glomerida (Glomeris, Loboglomeris) have eight pairs of mid-dorsally evacuating defensive glands, which contain a bitter-tasting, sticky, proteinaceous and colorless secretion. The glandular material contained the quinazolinone alkaloids 1,2-dimethyl-4-quinazolone (glomerin, 139) and 1-methyl-2-ethyl-4-quinazolone (homoglomerin, 140), which are unusual for animals12,167 and may deter and paralyze spiders, ants, carabid beetles, and vertebrates such as mice, birds, and toads. This contrasts with the large armored pill millipedes of the genus Sphaerotherium, which are devoid of defensive secretions. Mungos hurl these millipedes against a rock and subsequently smash them.168 These Glomerida alkaloids resemble quinazoline alkaloids such as arborine (2-benzyl-1-methylquinazol-4-one), recorded from Indian medicinal plants. Both 139 and 140 are produced from anthranilic acid as was shown by feeding glomerids with labeled precursors.165

Colobognatha, the neighbor group of Pentazonia, include chemically defended taxa with paired laterally arranged defensive glands in the order Polyzoniida. Polyzonium rosalbum emits a sticky whitish defensive fluid with a strong odor. The fluid consists of two spirocyclic terpene alkaloids, (+)-polyzonimine (6,6-dimethyl-2-azaspiro[4.4]non-1-ene, 145) and the related tricyclic (+)-nitropolyzonamine (2′,2′-dimethyl-6-nitrospiro-{1-azabicyclo[3.3.0]octane-4,1′-cyclopentane}, 146). Both compounds, which contain a 2-azaspiro[4.4]nonane system, represent ant deterrents and repellents.12 Enantiomerically pure 145 and 146 were synthesized by asymmetrical Michael addition of the enamine derived from 2,2-dimethylcyclopentanecarboxaldehyde and (S)-prolinol methyl ether to nitroethylene.169 Another polyzoniid species of the genus Buzonium secretes the interesting tetracyclic alkaloid buzonamine (143), an epoxy group, and a tertiary nitrogen.170 Apart from this ant repellent, the secretion contains limonene (74) and β-pinene (137). From a further polyzoniid species Rhinotus purpureus, the spiropyrrolizidine O-methyloxime was isolated (147).171 Because traces of this compound were also detected in skin extracts of sympatric poison frog Dendrobates pumilio, a dietary source of this alkaloid was supposed.

In Abacion magnum, a representative of the neighbor group Nematophora (Callipodida), the defensive secretion contained p-cresol (127).165

Chordeumatida - an overview | ScienceDirect Topics (5)

Several papers concerning the defensive secretions of Polydesmida (another neighbor group, also called Merocheta) have been published. Polydesmida possess segmentally arranged special reactor glands characterized by a reservoir, a smaller vestibule, and an opening valve between both compartments.165 Leonardesmus injucundus secretes p-cresol (127)172 and represents a primitive polydesmid, closely related to the callipodid Abacion. Most other representatives of polydesmid taxa165,173,174 produce mandelonitrile (133), the precursor of benzaldehyde (123), and hydrogen cyanide (112). Other polydesmid defensive compounds are benzoyl cyanide (134), mandelonitrile benzoate (135), 2-methoxyphenol (guaiacol, 131), phenol, benzoic acid (124), ethyl benzoate, formic acid (93), acetic acid (75), 3-methylbutanoic acid (92), 2-methylbutanoic acid, myristic acid (94), and stearic acid (95). Erratically distributed polydesmid compounds are benzaldehyde dimethyl acetal (132) and 2-methoxy-4-methylphenol (creosol, 125) in Chamberlinius175 and Oxidus;176 1-octen-3-ol (100) and geosmin (136) in Niponia;177 and (1E)- (138) and (1Z)-2-nitroethenylbenzene (E/Z ratio: 56:1; 2–3μg per millipede) in Eucondylodesmus.178

Chordeumatida - an overview | ScienceDirect Topics (6)

The polydesmid secretions represent effective repellents against ants, lizards, and birds but compounds such as 124, 134, and 138 also inhibit mycelial growth and spore germination.179 In addition, 138 has antibacterial and insecticidal properties.178 Quantitative differences were recorded in developing female polydesmids, when titers of methyl benzoate and 131 were compared, which indicates that the compounds may also have certain physiological functions related to reproduction and development.175 Moreover, in another species, males contained twice as much 123 and 133 compounds as females.180 Finally, Ômura et al.177 suggested that 1-octen-3-ol, which is a typical mushroom volatile, might also act as an alarm pheromone. It is interesting to note that l-phenylalanine is used as a precursor for both 2-nitroethenylbenzene178 and mandelonitrile,165 which was proved by using the labeled precursor [2-14C]phenylalanine and α,β,β,2,3,4,5,6-d8-l-phenylalanine, respectively. Moreover, by using 14C-labeled precursors it was shown that phenol and guaiacol (131) are derived from tyrosine, whereas H14CN is detoxified and converted primarily to thiocyanate by rhodanase with minor conversion to β-cyanoalanine and asparagine.181

Most chemically studied millipedes belong to the Juliformia with Julida, Spirobola, and Spirostreptida.165 Segmentally arranged glands represent spherical sacs with efferent ducts and opening muscles near the outer orifice.165 The secretions of the three orders are characterized primarily by p-benzoquinones such as 2-methyl-1,4-benzoquinone (114), 2-methyl-3-methoxy-1,4-benzoquinone (115), 1,4-benzoquinone (113), 2,3-dimethoxy-1,4-benzoquinone (119), 5-methyl-2,3-dimethoxy-1,4-benzoquinone (120), 2-methyl-1,4-hydroquinone (128), and 2-methyl-3-methoxy-1,4-hydroquinone (130). In a few species, o-cresol (126), hexadecyl acetate (96), 9-hexadecenyl acetate (97), 9-octadecenyl acetate (98), and (E2)-dodecenal (99) could be detected. Further defensive compounds that are erratically distributed in Spirobolida are 2-ethyl-1,4-benzoquinone (49), 2-hydroxy-3-methyl-1,4-benzoquinone (122), hydroquinone, 2-methoxy-3,6-dimethyl-1,4-benzoquinone (121), 2,3-dimethoxyhydroquinone, 2-methyl-3,4-methylenedioxyphenol (129), 2,3-dimethoxy-5-methylhydroquinone in Acladocricus182 and some Floridobolus species.183 The neotropical spirobolid Rhinocricus padbergi is unusual in secreting the alkaloid 3,3a,4,5-tetrahydro-1H-pyrrolo-[2,3-b]pyridine-2,6-dione (144), together with 114 and linear hydrocarbons from C21 (heneicosane) to C29 (nonacosane).184 New constituents in the spirostreptid Telodeinopus aoutii are 2-methoxy-1,4-benzoquinone (118) and naphthoquinone (53). In a harpagophorid species, the presence of 2-methoxyhydroquinone is worth mentioning.185 Apart from stereotypic quinones and hydroquinones, several julid species of the genera Julus, Leptoiulus, Ommatoiulus, Tachypodoiulus, Enantiulus, and Cylindroiulus contained 2-methoxy-5-methyl-1,4-benzoquinone (116), 2-methoxy-6-methyl-1,4-benzoquinone (117), a homologous series of hexyl esters ranging from dodecanoic acid hexyl ester (101), tridecanoic acid hexyl ester (102), tetradecanoic acid hexyl ester, pentadecanoic acid hexyl ester (103), hexadecanoic acid hexyl ester (104), octadecanoic acid hexyl ester (105) to eicosanoic acid hexyl ester (106).186 Cylindroiulus caeruleocinctus exclusively shows n-alkanols comprising 1-octanol (111), 1-nonanol (110), 1-decanol (109), 1-dodecanol (108), and 8-methyl-1-nonanol (107).186

Various data exist on the biological significance of diplopod defensive chemicals. Compounds such as 114, 115, 123, 124, 134, and 135 are toxic to fungi,187 nematodes, and bacteria.188 It was also suggested that, similar to opilionid defensive secretions, minor components such as 47 and 48 contribute much more to the antibiotic activity of the whole secretion than the main constituent 46.186 As demonstrated in Ommatoiulus sabulosus, its defensive secretions are repulsive to vertebrates, which exhibit an avoidance behavior.189 Quinazolinones from Glomeris can induce a significant spider sedation.190 In addition, certain vertebrates such as capuchin monkeys frequently use diplopods and their secretions to deter mosquitoes and ticks.191 Moreover, diplopod defensive compounds such as 114 and 115 attract certain necrophagous dung beetles, which normally feed on freshly dead millipedes.192

Millipedes may show bioluminescence after molestation. The luminescent system of Luminodesmus sequoiae (now Motyxia sequoiae) is activated by ATP, magnesium, and molecular oxygen and involves a 104kDa luciferase.193 Although the details of the mechanisms are unknown, it was concluded that 7,8-dihydropterin-6-carboxylic acid (141) is the light emitter.141,194

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The chemical defenses of millipedes (diplopoda): Biochemistry, physiology and ecology

William A. Shear, in Biochemical Systematics and Ecology, 2015

14.3.3 Polydesmida

The largest question in millipede phylogenetics is the correct position of the Polydesmida, which classically has been placed in its own superorder Merochaeta. However, Shear etal. (2003), without a matrix-based analysis, suggested an “eighth gonopod clade” consisting of Polydesmida, Callipodida, Chordeumatida and Stemmiulida. Characters supporting this hypothesis are the metamorphosis-like, abrupt development of gonopods from the eighth legpair, the vas deferens opening through the second leg coxae, and the presence of spinnerets on the telson. This clade is present in the analyses of Sierwald etal. (2003) and Blanke and Wesener (2013) but has not been found in any analysis based on genetic data. There, the polydesmids have “bounced around” as sister to Colobognatha, to Julida, or to all other Eugnatha. However, even the most recent of these analyses (Brewer and Bond, 2013) was characterized by very incomplete taxon sampling, leaving out representatives of five orders. Cyanogenesis in polydesmidans is an autapomorphy and thus uninformative, but the presence of phenol and phenolic derivatives such as cresols and guaiacol in numerous species provides a link to the cresol-producing Callipodida and Stemmiulida. Unfortunately there is no well-supported phylogeny of the families of Polydesmida, but most authorities have considered Paradoxosomatidae to be basal in the order, and it is here that phenolic compounds are most commonly found. The presence of the cyanogenic system in this putatively basal family also suggests that where cyanogenesis does not occur in the order, it is due to a loss. I would also go so far as to hypothesize that the cyanogenic system developed in response to vertebrate predation; it has been noted that HCN is not repellent to ants, and the largest producers of HCN (such as xystodesmids) display aposematic signals directed at visual predators. When cyanogenesis has been lost, it has been replaced by (possibly retained?) phenolics, and this occurs in small, cryptic species unlikely to be preyed upon by vertebrates.

Brewer and Bond (2013) did not recover a monophyletic Nematophora; instead Stemmiulida was sister to Juliforma and two of the orders of traditional Nematophora (i.e., Stemmilulida (Juliforma (Callipodida+Chordeumatida)). However, our preliminary results from at least three species of Stemmiulus gave p-cresol, also produced by callipodidans, and therefore provides at least some support for a monophyletic Nematophora. However, the spinnerets of stemmilulidans and siphonoiulidans, while similar to one another, differ anatomically from those of Polydesmida, Callipodida and Chordeumatida (Shear etal., 2007).

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Introduction: My name is Eusebia Nader, I am a encouraging, brainy, lively, nice, famous, healthy, clever person who loves writing and wants to share my knowledge and understanding with you.