Siphoniulus is a poorly known genus of millipede containing only two living species: S. alba from Indonesia, and S. neotropicus from Mexico and Guatemala. An additional two fossil species are known from Cretaceous amber. Siphoniulus species are the only members of the familySiphoniulidae and orderSiphoniulida, making Siphoniulida the smallest millipede order. Few specimens are known, and their classification is contentious, although most recent studies place them as basal members of the Helminthomorpha ("worm-like millipedes").
Siphoniulids are small and eyeless.[1] The head is drawn out into a conical beak, and lacks Tömösváry organs. The body is relatively long and narrow, containing up to 51 segments and reaching up to 7.5 mm (0.30 in) long,[a] and 0.25 mm (0.01 in) wide. The body color ranges from pure white to tan, and has been described as resembling a nematode.[2][3] The exoskeleton is smooth and has few setae, and ozopores (defensive glands) are lacking. The third segment is legless. Males possess a single pair of gonopods (modified copulatory legs) consisting of the anterior limbs on the seventh segment, and which are partially recessed into the body. The telson (rear-most segment) possesses small bristle-like structures called spinnerets.[2]
Distributionedit
S. alba is only known from a single specimen collected in 1894 near Maninjau on the Indonesian island of Sumatra. S. neotropicus was discovered near the Mayan ruins of Tikal in Guatemala, and is also known from the Mexican states of Chiapas and Veracruz.[2] The extinct species S. muelleri and S. preciosus are known from Late Cretaceous Burmese amber.[4]
Historyedit
Siphoniulus alba (and the family Siphoniulidae) was described in 1894 by R. I. Pocock, from a female specimen collected near Maninjau on the island of Sumatra.[5] The specimen was deposited in the Zoological Museum Amsterdam, but by 1975 the specimen was missing its head and anterior segments.[3]S. neotropicus was described by Richard L. Hoffman in 1979 from two possibly immature females collected in Guatemala.[3] Males of either species were unknown until 2003, when samples of leaf litter from Mexico sorted by researchers at the Field Museum of Natural History revealed new specimens of S. neotropicus, allowing for complete anatomical descriptions and characterization of the gonopods.[2]
Combining morphological with molecular data improved resolution, and also supported a basal helminthomorph placement of Siphoniulida.
Siphoniulids have been classified in various, conflicting placements within the Helminthomorpha ("worm-like" millipedes) since their initial description, and their relation to the rest of millipedes is still unresolved. When first described, the family Siphoniulidae was placed in the "Suborder" Colobognatha, a group that is now recognized as a larger grouping including the orders Platydesmida, Polyzoniida, and Siphonophorida.[5] The following year, the American entomologist Orator F. Cook considered Stemiulids as "suborder Siphoniuloidea", closely related to Julidans and Spirostreptidans (a grouping termed Diplochaeata). In 1979, Hoffman placed Siphoniulida (now considered an order) as Helminthomorph incertae sedis, meaning the placement within Helminthomorphs was undetermined, due to the absence of male specimens.[7][b] With only two known species, Siphoniulida is the smallest order of millipedes, followed by Siphonocryptida with three to six species.[8][9]
In more recent years, millipedes have been studied by cladistic and modern phylogenetic methods, yet Siphoniulida remains enigmatic. In the first cladistic study of millipedes, Enghoff could only place Siphoniulids as incertae sedis within the Helminthomorpha, but "probably... a specialized subordinate taxon within some juliform or colobognathan order".[10] However, in the first morphological study of millipede phylogeny incorporating full details of Siphoniulus anatomy, Siphoniulida did not appear closely related to the Juliformia nor Colobognatha, but rather appeared as an outgroup to all other helminthomorphs, and the internal classification of Helminthomorpha was poorly resolved and significantly differed from Enghoff's.[2] In a subsequent study combining anatomical data with DNA sequence data from other groups, Siphoniulida again appeared as basal within Helminthomorpha.[6]
Notesedit
^The holotype and only known specimen of S. alba was described as 11 mm, but the anterior part of it is now missing.[2]
^Gonopod morphology is one of the primary diagnostic traits in millipedes.
Referencesedit
^Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida
^ abcdefgSierwald, P.; Shear, W. A.; Shelley, R. M.; Bond, J. E. (2003). "Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida". Journal of Zoological Systematics and Evolutionary Research. 41 (2): 87–99. doi:10.1046/j.1439-0469.2003.00202.x.
^ abcHoffman, R.L. (1979). "A siphoniulid milliped from Central America". Revue Suisse de Zoologie. 86: 535–540. doi:10.5962/bhl.part.82318.
^Liu, Weixin; Rühr, Peter T.; Wesener, Thomas (2017). "A look with μCT technology into a treasure trove of fossils: The first two fossils of the millipede order Siphoniulida discovered in Cretaceous Burmese amber (Myriapoda, Diplopoda)". Cretaceous Research. 74: 100–108. doi:10.1016/j.cretres.2017.01.009.
^ abPocock, R. I. (1894). "Chilopoda, Symphyla and Diplopoda from the Malay Archipelago". Zoologische Ergebnisse einer Reise in Niederländisch Ost-Indien. 3: 307–404..
^ abSierwald, Petra; Bond, Jason E. (2007). "Current Status of the Myriapod Class Diplopoda (Millipedes): Taxonomic Diversity and Phylogeny". Annual Review of Entomology. 52 (1): 401–420. doi:10.1146/annurev.ento.52.111805.090210. PMID 17163800.
^Hoffman RL. (1979) Classification of the Diplopoda. Geneve: Mus. Hist. Nat. 237 pp.
^Brewer, Michael S.; Sierwald, Petra; Bond, Jason E. (2012). "Millipede Taxonomy after 250 Years: Classification and Taxonomic Practices in a Mega-Diverse yet Understudied Arthropod Group". PLOS ONE. 7 (5): e37240. Bibcode:2012PLoSO...737240B. doi:10.1371/journal.pone.0037240. PMC3352885. PMID 22615951.
^Enghoff, H. (2010). "A new strikingly coloured species of Siphonocryptus, sixth of its order (Diplopoda: Siphonocryptida)" (PDF). Zootaxa. 2681: 66–68. doi:10.11646/zootaxa.2681.1.6.
^Enghoff, H. (1984). "Phylogeny of millipedes - a cladistic analysis". Journal of Zoological Systematics and Evolutionary Research. 22 (1): 8–26. doi:10.1111/j.1439-0469.1984.tb00559.x.
A siphoniulid milliped from Central America, Hoffman's 1979 original description of Siphoniulus neotropicus with photograph and illustrations.
January 01, 1970
siphoniulus, poorly, known, genus, millipede, containing, only, living, species, alba, from, indonesia, neotropicus, from, mexico, guatemala, additional, fossil, species, known, from, cretaceous, amber, species, only, members, family, siphoniulidae, order, sip. Siphoniulus is a poorly known genus of millipede containing only two living species S alba from Indonesia and S neotropicus from Mexico and Guatemala An additional two fossil species are known from Cretaceous amber Siphoniulus species are the only members of the family Siphoniulidae and order Siphoniulida making Siphoniulida the smallest millipede order Few specimens are known and their classification is contentious although most recent studies place them as basal members of the Helminthomorpha worm like millipedes SiphoniulusTemporal range Cenomanian Present PreꞒ Ꞓ O S D C P T J K Pg N Two views of Siphoniulus alba head Scientific classification Kingdom Animalia Phylum Arthropoda Subphylum Myriapoda Class Diplopoda Order SiphoniulidaCook 1895 Family SiphoniulidaePocock 1894 Genus SiphoniulusPocock 1894 Species S alba Pocock 1894 S neotropicus Hoffman 1979 S muelleri S preciosus Contents 1 Description 2 Distribution 3 History 4 Classification 5 Notes 6 References 7 External linksDescription editSiphoniulids are small and eyeless 1 The head is drawn out into a conical beak and lacks Tomosvary organs The body is relatively long and narrow containing up to 51 segments and reaching up to 7 5 mm 0 30 in long a and 0 25 mm 0 01 in wide The body color ranges from pure white to tan and has been described as resembling a nematode 2 3 The exoskeleton is smooth and has few setae and ozopores defensive glands are lacking The third segment is legless Males possess a single pair of gonopods modified copulatory legs consisting of the anterior limbs on the seventh segment and which are partially recessed into the body The telson rear most segment possesses small bristle like structures called spinnerets 2 Distribution editS alba is only known from a single specimen collected in 1894 near Maninjau on the Indonesian island of Sumatra S neotropicus was discovered near the Mayan ruins of Tikal in Guatemala and is also known from the Mexican states of Chiapas and Veracruz 2 The extinct species S muelleri and S preciosus are known from Late Cretaceous Burmese amber 4 History editSiphoniulus alba and the family Siphoniulidae was described in 1894 by R I Pocock from a female specimen collected near Maninjau on the island of Sumatra 5 The specimen was deposited in the Zoological Museum Amsterdam but by 1975 the specimen was missing its head and anterior segments 3 S neotropicus was described by Richard L Hoffman in 1979 from two possibly immature females collected in Guatemala 3 Males of either species were unknown until 2003 when samples of leaf litter from Mexico sorted by researchers at the Field Museum of Natural History revealed new specimens of S neotropicus allowing for complete anatomical descriptions and characterization of the gonopods 2 Classification editSimplified cladogram from Sierwald et al 2003 2 Polyxenida Chilognatha Pentazonia Helminthomorpha Siphoniulida Chordeumatida Colobognatha Platydesmida Siphonophorida Polyzoniida Juliformia Julida Spirobolida Spirostreptida Stemmiulida Callipodida Polydesmida The incorporation of Siphoniulida anatomy did not clearly resolve relationships of millipede orders Simplified cladogram from Sierwald amp Bond 2007 6 Polyxenida Chilognatha Pentazonia Helminthomorpha Siphoniulida Stemmiulida Polydesmida Polyzoniida Siphonophorida Siphonocryptida Platydesmida Chordeumatida Callipodida Juliformia Spirobolida Spirostreptida Julida Combining morphological with molecular data improved resolution and also supported a basal helminthomorph placement of Siphoniulida Siphoniulids have been classified in various conflicting placements within the Helminthomorpha worm like millipedes since their initial description and their relation to the rest of millipedes is still unresolved When first described the family Siphoniulidae was placed in the Suborder Colobognatha a group that is now recognized as a larger grouping including the orders Platydesmida Polyzoniida and Siphonophorida 5 The following year the American entomologist Orator F Cook considered Stemiulids as suborder Siphoniuloidea closely related to Julidans and Spirostreptidans a grouping termed Diplochaeata In 1979 Hoffman placed Siphoniulida now considered an order as Helminthomorph incertae sedis meaning the placement within Helminthomorphs was undetermined due to the absence of male specimens 7 b With only two known species Siphoniulida is the smallest order of millipedes followed by Siphonocryptida with three to six species 8 9 In more recent years millipedes have been studied by cladistic and modern phylogenetic methods yet Siphoniulida remains enigmatic In the first cladistic study of millipedes Enghoff could only place Siphoniulids as incertae sedis within the Helminthomorpha but probably a specialized subordinate taxon within some juliform or colobognathan order 10 However in the first morphological study of millipede phylogeny incorporating full details of Siphoniulus anatomy Siphoniulida did not appear closely related to the Juliformia nor Colobognatha but rather appeared as an outgroup to all other helminthomorphs and the internal classification of Helminthomorpha was poorly resolved and significantly differed from Enghoff s 2 In a subsequent study combining anatomical data with DNA sequence data from other groups Siphoniulida again appeared as basal within Helminthomorpha 6 Notes edit The holotype and only known specimen of S alba was described as 11 mm but the anterior part of it is now missing 2 Gonopod morphology is one of the primary diagnostic traits in millipedes References edit Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida a b c d e f g Sierwald P Shear W A Shelley R M Bond J E 2003 Millipede phylogeny revisited in the light of the enigmatic order Siphoniulida Journal of Zoological Systematics and Evolutionary Research 41 2 87 99 doi 10 1046 j 1439 0469 2003 00202 x a b c Hoffman R L 1979 A siphoniulid milliped from Central America Revue Suisse de Zoologie 86 535 540 doi 10 5962 bhl part 82318 Liu Weixin Ruhr Peter T Wesener Thomas 2017 A look with mCT technology into a treasure trove of fossils The first two fossils of the millipede order Siphoniulida discovered in Cretaceous Burmese amber Myriapoda Diplopoda Cretaceous Research 74 100 108 doi 10 1016 j cretres 2017 01 009 a b Pocock R I 1894 Chilopoda Symphyla and Diplopoda from the Malay Archipelago Zoologische Ergebnisse einer Reise in Niederlandisch Ost Indien 3 307 404 a b Sierwald Petra Bond Jason E 2007 Current Status of the Myriapod Class Diplopoda Millipedes Taxonomic Diversity and Phylogeny Annual Review of Entomology 52 1 401 420 doi 10 1146 annurev ento 52 111805 090210 PMID 17163800 Hoffman RL 1979 Classification of the Diplopoda Geneve Mus Hist Nat 237 pp Brewer Michael S Sierwald Petra Bond Jason E 2012 Millipede Taxonomy after 250 Years Classification and Taxonomic Practices in a Mega Diverse yet Understudied Arthropod Group PLOS ONE 7 5 e37240 Bibcode 2012PLoSO 737240B doi 10 1371 journal pone 0037240 PMC 3352885 PMID 22615951 Enghoff H 2010 A new strikingly coloured species of Siphonocryptus sixth of its order Diplopoda Siphonocryptida PDF Zootaxa 2681 66 68 doi 10 11646 zootaxa 2681 1 6 Enghoff H 1984 Phylogeny of millipedes a cladistic analysis Journal of Zoological Systematics and Evolutionary Research 22 1 8 26 doi 10 1111 j 1439 0469 1984 tb00559 x External links edit nbsp Arthropods portal A siphoniulid milliped from Central America Hoffman s 1979 original description of Siphoniulus neotropicus with photograph and illustrations Retrieved from https en wikipedia org w index php title Siphoniulus amp oldid 1136122828, wikipedia, wiki, book, books, library,
