Tetramerocerata | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Myriapoda |
Class: | Pauropoda |
Order: | Tetramerocerata Remy, 1950 |
Tetramerocerata is an order of pauropods containing 11 families and more than 900 species. [1] This order was created in 1950 to distinguish these pauropods from those in the newly discovered genus Millotauropus , which was found to have such distinctive features as to warrant placement in a separate order (Hexamerocerata) created to contain that genus. [2] The order Tetramerocerata includes the vast majority of pauropod species, as there are only eight species in the order Hexamerocerata, which remains the only other order in the class Pauropoda. [3]
Adult pauropods in the order Tetramerocerata feature antennae that have four stalk segments and are not telescopic, whereas species in the order Hexamerocerata have strongly telescopic antennae with six stalk segments. [2] Two antennal branches emerge from the distal end of the fourth segment in Tetramerocerata, one dorsal and one ventral; in Hexamerocerata, however, the dorsal branch emerges from the distal end of the fifth segment, and the ventral branch emerges from the distal end of the sixth segment. [2] [4] In Tetramerocerata, the ventral branch features two long flagella, one anterior and one posterior, but the dorsal branch features only one; in Hexamerocerata, each branch features only one flagellum. In Tetramerocerata, the distal part of the ventral antennal branch also features a spheroid sense organ, the globulus. The lateral sides of the head feature two large eye-like organs, and in Tetramerocerata, these temporal organs are flat or somewhat convex; in Hexamerocerata, these organs are shaped like cups or umbrellas attached to a shallow depression in the head. [4]
Adults in the order Tetramerocerata have trunks with six tergites that may be entire or divided, whereas those in the order Hexamerocerata have twelve entire tergites. [4] [2] Although there are twelve trunk segments, in Tetramerocerata, the first, fourth, sixth, eighth, tenth, and twelfth segments are so short that the entire dorsal surface is covered by the tergites of the second, third, fifth, seventh, ninth, and eleventh segments. In Tetramerocerata, the ventral surface of the first trunk segment, the collum, features two appendages with a plate in between protruding in the anterior direction; in Hexamerocerata, this ventral surface is smooth. In Tetramerocerata, the tergum of the last trunk segment, the pygidium, features four pairs of setae; this tergum in Hexamerocerata features five to eight pairs of setae. [4]
Most adults in the order Tetramerocerata have nine leg pairs. [5] Adults in four genera ( Cauvetauropus , Aletopauropus , Zygopauropus , and Amphipauropus) have only eight pairs, however, and adult females in the genus Decapauropus (in the Pauropodidae family) have either nine or ten pairs of legs. [4] [2] Adults in the order Hexamerocerata have eleven leg pairs. [4]
The mouthparts in the order Tetramerocerata are weaker than those found in the order Hexamerocerata. The mandibles in Tetramerocerata are adapted for sucking fluids and are used to puncture cell walls. No solid food has been found in the midgut of pauropods in the order Tetramerocerata. The mandibles in the order Hexamerocerata, however, are strong enough to allow the consumption of solid food, and the midgut of pauropods in Hexamerocerata can contain fungus, spores, and plant tissue. [4]
Most species in the order Tetramerocerata develop through a series of five post-embryonic stages, from the first instar to the adult. Juveniles in this order begin with three pairs of legs and three tergites, then in most species in this order, they become adults with nine leg pairs and six tergites. Pauropods in this order have three leg pairs in the first stage, then five pairs in the second, six pairs in the third, eight pairs in the fourth, and for most species in this order, nine pairs in the fifth (adult) stage. Juveniles in the order Hexamerocerata, however, begin with six leg pairs and eight tergites, then become adults with eleven leg pairs and twelve tergites, going through stages with six, eight, nine, ten, and eleven leg pairs. [4]
Tetramerocerata has a subcosmopolitan distribution, with species found nearly worldwide. [2]
This order includes the following families: [4] [1]
Pauropoda is a class of small, pale, millipede-like arthropods in the subphylum Myriapoda. More than 900 species in twelve families are found worldwide, living in soil and leaf mold. Pauropods look like centipedes or millipedes and may be a sister group of the latter, but a close relationship with Symphyla has also been posited. The name Pauropoda derives from the Greek pauros and pous or podus, because most species in this class have only nine pairs of legs as adults, a smaller number than those found among adults in any other class of myriapods.
Symphylans, also known as garden centipedes or pseudocentipedes, are soil-dwelling arthropods of the class Symphyla in the subphylum Myriapoda. Symphylans resemble centipedes, but are very small, non-venomous, and only distantly related to both centipedes and millipedes. More than 200 species are known worldwide.
Myriapods are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial.
Pauropodidae is the most diverse family of pauropods, containing 27 genera and more than 800 species. This family has a subcosmopolitan distribution. These pauropods usually live in the soil on mountains and hills. This family also includes the only known fossil pauropod (Eopauropus).
Arthropleura is a genus of massive myriapod that lived in what is now Europe and North America around 345 to 290 million years ago, from the Viséan stage of the lower Carboniferous Period to the Sakmarian stage of the lower Permian Period. It is related to millipedes, and was capable of reaching at least 2 metres in length, possibly up to over 2.5 metres, making it the largest known land arthropod of all time. Arthropleura is known from body fossils as well as trace fossils, particularly giant trackways up to 50 centimetres (20 in) wide, and potentially also large burrows. It lived in open, sparsely wooded environments near water, and was possibly amphibious.
Glomerida is an order of pill-millipedes found primarily in the Northern Hemisphere. Also known as northern pill millipedes, they superficially resemble pill-bugs or woodlice, and can enroll into a protective ball. They have twelve body segments, 17 to 19 pairs of legs, and males have enlarged rear legs involved in mating. The order includes about 30 genera and at least 280 species, including Glomeris marginata, the common European pill-millipede. The order contains members in Europe, South-east Asia and the Americas from California to Guatemala. Although historically considered closely related with the similar sphaerotheriidans that also enroll, some DNA evidence suggest they may be more closely related to glomeridesmidans, a poorly known order that does not enroll.
Opiliones are an order of arachnids and share many common characteristics with other arachnids. However, several differences separate harvestmen from other arachnid orders such as spiders. The bodies of opiliones are divided into two tagmata : the abdomen (opisthosoma) and the cephalothorax (prosoma). Unlike spiders, the juncture between the abdomen and cephalothorax is often poorly defined. Harvestmen have chelicerae, pedipalps and four pairs of legs. Harvestmen were traditionally thought to have two eyes, except in the case of eyeless species. Developmental genetic work has shown that living species retain up to six eyes, including one pair of rudimentary median eyes and one pair of rudimentary lateral eyes.
Scutigeromorpha is an order of centipedes also known as house centipedes. These centipedes are found in the temperate and tropical parts of every continent except Antarctica, with their distribution significantly expanded by the introduction of the Mediterranean species Scutigera coleoptrata throughout Europe, Asia, and North America. The common species S. coleoptrata is a typical representative of this order, lying in wait for other arthropods, then seizing prey using great speed, and all species in this order reflect adaptations for this mode of life.
Insect morphology is the study and description of the physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical features separate insects from other arthropods: they have a body divided into three regions, three pairs of legs, and mouthparts located outside of the head capsule. This position of the mouthparts divides them from their closest relatives, the non-insect hexapods, which include Protura, Diplura, and Collembola.
Dipteran morphology differs in some significant ways from the broader morphology of insects. The Diptera is a very large and diverse order of mostly small to medium-sized insects. They have prominent compound eyes on a mobile head, and one pair of functional, membraneous wings, which are attached to a complex mesothorax. The second pair of wings, on the metathorax, are reduced to halteres. The order's fundamental peculiarity is its remarkable specialization in terms of wing shape and the morpho-anatomical adaptation of the thorax – features which lend particular agility to its flying forms. The filiform, stylate or aristate antennae correlate with the Nematocera, Brachycera and Cyclorrhapha taxa respectively. It displays substantial morphological uniformity in lower taxa, especially at the level of genus or species. The configuration of integumental bristles is of fundamental importance in their taxonomy, as is wing venation. It displays a complete metamorphosis, or holometabolous development. The larvae are legless, and have head capsules with mandibulate mouthparts in the Nematocera. The larvae of "higher flies" (Brachycera) are however headless and wormlike, and display only three instars. Pupae are obtect in the Nematocera, or coarcate in Brachycera.
Juliformia is a taxonomic superorder of millipedes containing three living orders: Julida, Spirobolida, and Spirostreptida, and the extinct group Xyloiuloidea known only from fossils.
Millotauropus is a genus of pauropods in the monotypic family Millotauropodidae in the monotypic order Hexamerocerata. The order Hexamerocerata includes only eight species and was created in 1950 to contain the newly discovered genus Millotauropus, which was found to have so many distinctive features as to warrant placement in a separate order. Before the discovery of Millotauropus, for example, pauropods were thought to have no more than ten leg pairs, but adults in the order Hexamerocerata have eleven pairs of legs.
Bucolus fourneti is a native Australian, small, hairy coccinellid beetle approximately 2.1-4.5 mm in diameter. It was described by Étienne Mulsant in 1850
Brachypauropodidae is a family of pauropods. This family has a nearly worldwide distribution. Pauropods in this family are found on all continents except South America and Antarctica.
Linotaeniidae are a monophyletic clade of soil centipedes in the family Geophilidae found mostly in the temperate regions of the Holarctic as well as the south Andes. Species in the clade Linotaeniidae are characterized by a body that usually tapers toward the anterior tip; mandibles with a single pectinate lamella; second maxillae with coxo-sternite usually undivided and claws without projections; forcipular segment short, with tergite remarkably wide, forcipules evidently tapering; coxal organs opening through distinct pores on the ventral surface of the coxo-pleura. The number of legs in this clade varies within as well as among species and ranges from as few as 31 pairs of legs to as many as 83 leg pairs. Compared to most families in the suborder Adesmata, this clade features a modest number of leg-bearing segments and limited variation in this number within each species.
Perothops is a genus of false click beetles in the family Eucnemidae containing 3 species. They are known as beech-tree beetles or perothopid beetles. They are small as they are only 10–18 millimeters long. It is the only genus in the monotypic subfamily Perothopinae. They are dark-colored beetles that are found across the United States, generally in forests. The genus was discovered by Johann Friedrich von Eschscholtz in 1836. It used to be considered a family not part of Eucnemidae. The genus's name is from Greek, translating to "maimed/crippled eye" or "eye of little necklaces/bands", referring to the placement of perothopid eyes.
Zygopauropus is a monotypic genus of pauropod in the family Brachypauropodidae. The only species in this genus is Zygopauropus hesperius, which is found in the western United States. This genus is notable as one of only four genera of pauropods in which adults have only eight pairs of legs rather than the nine leg pairs usually found in adults in the order Tetramerocerata. Before the discovery of Zygopauropus, adult pauropods were thought to have only nine or (rarely) ten pairs of legs.
Decapauropus is a large genus of pauropods in the family Pauropodidae that includes more than 300 species. This genus was originally described by the French zoologist Paul Remy in 1931 to contain the newly discovered type species Decapauropus cuenoti. As the name of this genus suggests, this genus is notable for including females with ten pairs of legs instead of the nine leg pairs usually found in adult pauropods in the order Tetramerocerata. Before the discovery of D. cuenoti, adult pauropods were thought to have invariably nine pairs of legs.
Decapauropus cuenoti is a species of pauropod in the family Pauropodidae. As the name of the genus Decapauropus suggests, this species is notable for including females with ten pairs of legs instead of the nine leg pairs usually found in adult pauropods in the order Tetramerocerata. Before the discovery of D. cuenoti, adult pauropods were thought to have invariably nine pairs of legs.