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| Burmanopetalum inexpectatum Stoev, Moritz & Wesener, 2019 |
Abstract
The entire Mesozoic Era is rather poor in millipede (class Diplopoda) fossils, with less than a dozen species being taxonomically described. Here, we describe the first fossil millipede of the order Callipodida, Burmanopetalum inexpectatum gen. nov. et sp. nov., found in early Cenomanian amber of Burma, 98.79±0.62 Mya. The species possesses a number of morphological traits that exclude it from all extant suborders, and Burmanopetalidea suborder nov. and Burmanopetalidae fam. nov. are here erected to accommodate it. The new suborder can be recognized by the following unique characters: pleurotergal setae absent; telson with a specific spatulate shape twice the size of the penultimate body ring; hypoproct devoid of setae; and eyes composed of five well-separated ommatidia. While the callipodidan habitus seems to have remained generally unchanged for at least 99 million years, pleurotergal and hypoproctal setation, as well as the complexity of eyes in ground-dwelling forms may have evolved recently in the order. As B. inexpectatum gen. nov. et sp. nov. is the first true callipodidan in the fossil record, the minimum age of Callipodida is thus at least 99 Mya.
Keywords: Burmanopetalidea suborder nov., Burmanopetalidae fam. nov., Burmanopetalum inexpectatum gen. nov. et sp. nov., Cenomanian, Mesozoic.
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| Burmanopetalum inexpectatum gen. nov. et sp. nov., female holotype (ZFMK-MYR07366) A habitus B head, anterior-most body rings and vulvae, anterior view C antennae, lateral view D pleurotergal crests ornamentation, lateral view E telson, lateral view F legs, dorsolateral view G apical part of vulva, lateral view H basal part of vulva, lateral view. |
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| Burmanopetalum inexpectatum gen. nov. et sp. nov., female holotype (ZFMK-MYR07366), volume rendering A habitus B head, collum and pleurotergite 2, lateral view C head, anterior view D Gnathochilarium, ventral view E midbody body ring, dorsoposterior view F telson, and the last 3 pleurotergites, lateral view G same, ventral view. |
Systematic palaeontology
Class Diplopoda de Blainville in Gervais, 1844
Subclass Chilognatha Latreille, 1802/1803
Infraclass Helminthomorpha Pocock, 1887
Superorder Nematophora Verhoeff, 1913
Order Callipodida Pocock, 1894
Suborder †Burmanopetalidea suborder nov.
Diagnosis: Body less than 10 mm, composed of 35 body rings (including collum and two apodous body rings) and telson. Eyes composed of five ommatidia situated in two rows (3+2). Body rings cylindrical, with fused tergites and pleurites and free sternites. Pleurotergites composed of smooth prozonites and carinate metazonites, latter being greater in diameter than prozonites. Pleurotergal crests most pronounced from 3rd to 8th pleurotergite. Pleurotergal setae absent; telson spatulate, twice the size of the penultimate body ring; hypoproct tripartite, devoid of setae.
The suborder comprises one family: †Burmanopetalidae fam. nov.
Family †Burmanopetalidae fam. nov.
Genus † Burmanopetalum gen. nov.
Etymology: From “Burma”, the country of origin, and “-petalum” a frequent generic termination in Callipodida. Gender: neuter.
Diagnosis: Differs from all extant genera of Callipodida by its minute size (less than 1 cm in length), lack of pleurotergal setae, and its spatulate telson being twice the size of the penultimate body ring. Eyes composed of five ommatidia.
†Burmanopetalum inexpectatum sp. nov.
Diagnosis: As for the suborder, family and genus. Species further characterized by antennomeres III–V strongly conical (infundibular), VI and VII subrectangular; metazonites with 28 more or less well-developed narrow, subparallel crests, well-separated from one another, poriferous crests missing.
Etymology: "inexpectatum" in Latin means "unexpected" referring to the stunning discovery of just a single specimen among the 529 millipede specimens so far found in Burmese amber. The species epithet is an adjective.
Locality and horizon: Burmese amber, early Cenomanian, 98.79±0.62 Mya (Shi et al. 2012) from the Noije Bum amber mine, Hukawng Valley, Kachin State, northern Myanmar.
Pavel Stoev, Leif Moritz and Thomas Wesener. 2019. Dwarfs under Dinosaur Legs: A New Millipede of the Order Callipodida (Diplopoda) from Cretaceous Amber of Burma. ZooKeys. 841: 79-96. DOI: 10.3897/zookeys.841.34991