Product Code Database
The Opiliones (formerly Phalangida) are an order of ,
Common name known as harvestmen, harvesters, or daddy long legs. Over 6,650 species of harvestmen have been discovered worldwide, although the total number of extant taxon species may exceed 10,000.Glauco Machado, Ricardo Pinto-da-Rocha & Gonzalo Giribet (2025). 9780674023437, Harvard University Press. ISBN 9780674023437 The order Opiliones includes five suborders: Cyphophthalmi, Eupnoi, Dyspnoi, Laniatores, and Tetrophthalmi, which were named in 2014.
Representatives of each extant suborder can be found on all continents except Antarctica.
Well-preserved fossils have been found in the 400-million-year-old of Scotland, and 305-million-year-old rocks in France. These fossils look surprisingly modern, indicating that their basic body shape developed very early on, and, at least in some taxa, has changed little since that time.
Their Phylogenetics position within the Arachnida is disputed; their closest relatives may be camel spiders (Solifugae) or a larger clade comprising horseshoe crabs, Ricinulei, and Arachnopulmonata (scorpions, pseudoscorpions, and Tetrapulmonata). Although superficially similar to and often misidentified as (order Araneae), the Opiliones are a distinct order that is not closely related to spiders. They can be easily distinguished from long-legged spiders by their fused body regions and single pair of eyes in the middle of the cephalothorax. Spiders have a distinct abdomen that is separated from the cephalothorax by a constriction, and they have three to four pairs of eyes, usually around the margins of the cephalothorax.
They also have no silk glands and therefore do not build webs. In some highly derived species, the first five abdominal segments are fused into a dorsal shield called the scute, which in most such species is fused with the carapace. Some such Opiliones only have this shield in the males. In some species, the two posterior abdominal segments are reduced. Some of them are divided medially on the surface to form two plates beside each other. The second pair of legs is longer than the others and function as antennae or feelers. In short-legged species, this may not be obvious.
The feeding apparatus (stomotheca) differs from most arachnids in that Opiliones can swallow chunks of solid food, not only liquids. The stomotheca is formed by extensions of the coxae of the and the first pair of legs.
Most Opiliones, except for Cyphophthalmi, have long been thought to have a single pair of camera-type eyes in the middle of the head, oriented sideways. Eyes in Cyphophthalmi, when present, are located laterally, near the ozopores. A 305-million-year-old fossilized harvestman with two pairs of eyes was reported in 2014. This find suggested that the eyes in Cyphophthalmi are not homologous to the eyes of other harvestmen. Many cave-adapted species are eyeless, such as the Brazilian Caecobunus termitarum (Grassatores) from termite nests, Giupponia chagasi (Gonyleptidae) from caves, most species of Cyphophthalmi, and all species of the Guasiniidae. However, recent work studying the embryonic development of the species Phalangium opilio and some Laniatores revealed that harvestman in addition to a pair of median eyes also have two sets of vestigial eyes: one median pair (homologous to those of and ), and one lateral pair (homologous to facetted eyes of horseshoe crabs and insects). This discovery suggests that the neuroanatomy of harvestmen is more primitive than derived arachnid groups, like spiders and scorpions. It also showed that the four-eyed fossil harvestman previously discovered is most likely a member of the suborder Eupnoi (true daddy-longlegs).
Harvestmen have a pair of prosomatic defensive () that secrete a peculiar-smelling fluid when disturbed. In some species, the fluid contains noxious quinones. They do not have book lungs, and breathe through tracheae. A pair of spiracles is located between the base of the fourth pair of legs and the abdomen, with one opening on each side. In more active species, spiracles are also found upon the tibia of the legs. They have a gonopore on the ventral cephalothorax, and the copulation is direct as Opiliones penis, unlike other arachnids. All species lay eggs.
Typical body length does not exceed , and some species are smaller than 1 mm, although the largest known species, Trogulus torosus (Trogulidae), grows as long as . The leg span of many species is much greater than the body length and sometimes exceeds and to in Southeast Asia. Most species live for a year.
Although parthenogenesis species do occur, most harvestmen reproduce sexually. Except from small fossorial species in the suborder Cyphophthalmi, where the males deposit a spermatophore, mating involves direct copulation. The females store the sperm, which is aflagellate and immobile, at the tip of her ovipositor. The eggs are fertilized during oviposition. The males of some species offer a secretion (nuptial gift) from their chelicerae to the female before copulation. Sometimes, the male guards the female after copulation, and in many species, the males defend territories. In some species, males also exhibit post-copulatory behavior in which the male specifically seeks out and shakes the female's sensory leg. This is believed to entice the female into mating a second time.
The female lays her eggs shortly after mating to several months later. Some species build nests for this purpose. A unique feature of harvestmen is that some species practice parental care, in which the male is solely responsible for guarding the eggs resulting from multiple partners, often against egg-eating females, and cleaning the eggs regularly. Paternal care has evolved at least three times independently: once in the clade Progonyleptoidellinae + Caelopyginae, once in the Gonyleptinae, and once in the Heteropachylinae. Parental care in opiliones probably evolved due to natural selection, while paternal care appears to be the result of sexual selection. Depending on circumstances such as temperature, the eggs may hatch at any time after the first 20 days, up to about half a year after being laid. Harvestmen variously pass through four to eight nymphal to reach maturity, with most known species having six instars.
Most species are nocturnal and colored in hues of brown, although a number of diurnal animal species are known, some of which have vivid patterns in yellow, green, and black with varied reddish and blackish mottling and reticulation.
Many species of harvestmen easily tolerate members of their own species, with aggregations of many individuals often found at protected sites near water. These aggregations may number 200 individuals in the Laniatores, and more than 70,000 in certain Eupnoi. behavior is likely a strategy against climatic odds, but also against predators, combining the effect of scent secretions, and reducing the probability of any particular individual being eaten.
Harvestmen clean their legs after eating by drawing each leg in turn through their jaws.
Other harvestmen may exhibit mimicry to resemble other species' appearances. Some Gonyleptidae individuals that produce translucid secretions have orange markings on their . This may have an aposematic role by mimicking the colouration of glandular emissions of two other quinone-producing species. Mimicry (Müllerian mimicry) occurring between Brazilian harvestmen that resemble others could be explained by convergent evolution.
Autotomised legs provide a further defence from predators because they can twitch for 60 seconds to an hour after detachment. This can also potentially serve as deflection from an attack and deceive a predator from attacking the animal. It has been shown to be successful against ants and spiders.
The legs continue to twitch after they are detached because 'pacemakers' are located in the ends of the first long segment (femur) of their legs. These pacemakers send signals via the nerves to the muscles to extend the leg and then the leg relaxes between signals. While some harvestman's legs twitch for a minute, others have been recorded to twitch up to an hour. The twitching has been hypothesised to function as an evolutionary advantage by keeping the attention of a predator while the harvestman escapes.
Several Opiliones in Argentina appear to be vulnerable, if not endangered. These include Pachyloidellus fulvigranulatus, which is found only on top of Cerro Uritorco, the highest peak in the Sierras Chicas chain (provincia de Cordoba) and Pachyloides borellii is in rainforest patches in northwest Argentina which are in an area being dramatically destroyed by humans. The cave-living Picunchenops spelaeus is apparently endangered through human action. So far, no harvestman has been included in any kind of a Red List in Argentina, so they receive no protection.
Maiorerus randoi has only been found in one cave in the Canary Islands. It is included in the Catálogo Nacional de especies amenazadas (National catalog of threatened species) from the Spain government.
Texella reddelli and Texella reyesi are listed as endangered species in the United States. Both are from caves in central Texas. Texella cokendolpheri from a cave in central Texas and Calicina minor, Microcina edgewoodensis, Microcina homi, Microcina jungi, Microcina leei, Microcina lumi, and Microcina tiburona from around springs and other restricted habitats of central California are being considered for listing as endangered species, but as yet receive no protection.
An urban legend claims that the harvestman is the most animal in the world; however, it possesses fangs too short or a mouth too round and small to bite a human, rendering it harmless (the same myth applies to Pholcus phalangioides and the Tipuloidea, which are both also called a "daddy longlegs").The Spider Myths Site: "Daddy-Longlegs" None of the known species of harvestmen have venom glands; their chelicerae are not hollowed fangs but grasping claws that are typically very small and not strong enough to break human skin.
Since the 1990s, study of the biology and ecology of harvestmen has intensified, especially in South America.
Early work on the developmental biology of Opiliones from the mid-20th century was resurrected by Prashant P. Sharma, who established Phalangium opilio as a model system for the study of arachnid comparative genomics and evolutionary-developmental biology.
The family Stygophalangiidae (one species, Stygophalangium karamani) from underground waters in North Macedonia is sometimes misplaced in the Phalangioidea. It is not a harvestman.
The oldest known harvestman, from the 410-million-year-old Devonian Rhynie chert, displayed almost all the characteristics of modern species, placing the origin of harvestmen in the Silurian, or even earlier. A recent molecular study of Opiliones, however, dated the origin of the order at about 473 million years ago (Mya), during the Ordovician.
No fossils of the Cyphophthalmi or Laniatores much older than 50 million years are known, despite the former presenting a basal clade, and the latter having probably diverged from the Dyspnoi more than 300 Mya.
Naturally, most finds are from comparatively recent times. More than 20 fossil species are known from the Cenozoic, three from the Mesozoic, and at least seven from the Paleozoic.
Brigantibunum listoni from East Kirkton near Edinburgh in Scotland is almost 340 million years old. Its placement is rather uncertain, apart from it being a harvestman.
From about 300 Mya, several finds are from the Coal Measures of North America and Europe. While the two described Nemastomoides species are currently grouped as Dyspnoi, they look more like Eupnoi.
Kustarachne tenuipes was shown in 2004 to be a harvestman, after residing for almost one hundred years in its own arachnid order, the "Kustarachnida".
Some fossils from the Permian are possibly harvestmen, but these are not well preserved.
Currently, no fossil harvestmen are known from the Triassic. So far, they are also absent from the Lower Cretaceous Crato Formation of Brazil, a Lagerstätte that has yielded many other terrestrial arachnids. An unnamed long-legged harvestman was reported from the Early Cretaceous of Koonwarra, Victoria, Australia, which may be a Eupnoi.
In England, the Opiliones are often called "" or "". Folk etymology explanations for this are numerous, such as that they appear during harvest season, or because of a superstitious belief that if one is killed there will be a bad harvest that year,Frank Cowan, Curious Facts in the History of Insects, p.321 but these are unfounded. More likely, as in other European languages which call them a word meaning "cutter" or "scyther", the original explanation is that their oddly shaped legs look like tiny or . The alternative name "shepherd spiders" is sometimes attributed to the assumption that Englishmen knew of the shepherds in the Landes region of France who traditionally used stilts to better observe their wandering flocks from a distance, and so were reminded of them by the long-legged arachnid, but is much more likely just an extension of this agricultural imagery, with the farmer's implement changed to a shepherd's crook rather than a reaping tool. Compare similar developments in the Dutch language words for Opiliones: (literally meaning "hay-wagon") and in southern dialects (literally "cowherd", one who herds cattle).
English speakers may colloquially refer to species of Opiliones as "" or "granddaddy longlegs". However, this name is also used for two other distantly related groups of : the crane flies of the superfamily Tipuloidea, as well as the Pholcidae of the family Pholcidae (which may be distinguished as ""), because of their similar appearance.
Behavior
Many species are omnivorous, eating primarily small and all kinds of plant material and fungi. Some are , feeding upon dead organisms, bird dung, and other Feces material. Such a broad range is unusual in arachnids, which are typically pure predators. Most hunting harvestmen ambush their prey, although active hunting is also found. Because their eyes cannot form images, they use their second pair of legs as antennae to explore their environment. Unlike most other arachnids, harvestmen do not have a sucking stomach or a filtering mechanism. Rather, they ingest small particles of their food, thus making them vulnerable to internal parasites such as .
Antipredator defences
Predators of harvestmen include a variety of animals, including some mammals, amphibians, and other arachnids like spiders and scorpions. Opiliones display a variety of primary and secondary defences against predation, ranging from morphological traits such as body armour to behavioral responses to chemical secretions. Some of these defences have been attributed and restricted to specific groups of harvestmen. (2025). 9780674023437, Harvard University Press. ISBN 9780674023437
Primary defences
Primary defences help the harvestmen avoid encountering a potential predator and include crypsis, aposematism, and mimicry.
Crypsis
Particular patterns or colour markings on harvestmen's bodies can reduce detection by disrupting the animals' outlines or providing camouflage. Markings on legs can cause an interruption of the leg outline and loss of leg proportion recognition.Cokendolpher pers. comm. Darker colourations and patterns function as camouflage when they remain motionless.Gnaspini, P., Cavalheiro, A.J., 1998. Chemical and Behavioral Defensces of a Neotropical Cavernicolous Harvestman: Goniosoma spelaeum (Opiliones, Laniatores, Gonyleptidae). J. Arachnol. 26, 81–90. Within the genus Leiobunum are multiple species with cryptic colouration that changes over ontogeny to match the Habitat used at each life stage.Edgar, A.L., 1971. Studies on the biology and ecology of Michigan Phalangida (Opiliones). Many species have also been able to camouflage their bodies by covering with secretions and debris from the leaf litter found in their environments. Some hard-bodied harvestmen have Epibiont cyanobacteria and Marchantiophyta growing on their bodies that suggest potential benefits for camouflage against large backgrounds to avoid detection by Diurnality predators.Machado, G., Vital, D.M., 2001. On the Occurrence of Epizoic Cyanobacteria and Liverworts on a Neotropical Harvestman (Arachnida: Opiliones) | BIOTROPICA
Aposematism and mimicry
Some harvestmen have elaborate and brightly coloured patterns or appendages which contrast with the body colouration, potentially serving as an aposematic warning to potential predators.Pomini, A.M., Machado, G., Pinto-da-Rocha, R., Macías-Ordóñez, R., Marsaioli, A.J., 2010. Lines of defence in the harvestman Hoplobunus mexicanus (Arachnida: Opiliones): Aposematism, stridulation, thanatosis and irritant chemicals. Biochem. Syst. Ecol. 38, 300–308. This mechanism is thought to be commonly used during daylight, when they could be easily seen by any predators.
Secondary defences
Secondary defences allow for harvestmen to escape and survive from a predator after direct or indirect contact, including Apparent death, freezing, bobbing, autotomy, fleeing, stridulation, retaliation and chemical secretions.
Thanatosis
Some animals respond to attacks by simulating an apparent death to avoid either detection or further attacks.Humphreys, R.K., Ruxton, G.D., 2018. A review of thanatosis (death feigning) as an anti-predator behaviour. Behav. Ecol. Sociobiol. 72, 22. Arachnids such as spiders practise this mechanism when threatened or even to avoid being eaten by female spiders after mating.Hansen, L.S., Gonzales, S.F., Toft, S., Bilde, T., 2008. Thanatosis as an adaptive male mating strategy in the nuptial gift–giving spider Pisaura mirabilis. Behav. Ecol. 19, 546–551.Jones, T.C., Akoury, T.S., Hauser, C.K., Moore, D., 2011. Evidence of circadian rhythm in antipredator behaviour in the orb-weaving spider Larinioides cornutus. Anim. Behav. 82, 549–555. Thanatosis is used as a second line of defence when detected by a potential predator and is commonly observed within the Dyspnoi and Laniatores suborders, with individuals becoming rigid with legs either retracted or stretched.Cokendolpher, J.C., 1987. Observations on the defensive behavior of a Neotropical Gonyleptidae (Arachnida, Opiliones). Revue Arachnologique, 7, pp.59–63.Eisner, T., Alsop, D., Meinwald, J., 1978. Secretions of Opilionids, Whip Scorpions and Pseudoscorpions, in: Arthropod Venoms, Handbook of Experimental Pharmacology / Handbuch Der Experimentellen Pharmakologie. Springer, Berlin, Heidelberg, pp. 87–99.Machado, G., Pomini, A.M., 2008. Chemical and behavioral defences of the neotropical harvestman Camarana flavipalpi (Arachnida: Opiliones). Biochem. Syst. Ecol. 36, 369–376.Pereira, W., Elpino-Campos, A., Del-Claro, K., Machado, G., 2004. Behavioral repertory of the neotropical harvestman ilhaia cuspidata (opiliones, gonyleptidae). J. Arachnol. 32, 22–30.
Freezing
Freezing – or the complete halt of movement – has been documented in the family Sclerosomatidae.Misslin, R., 2003. The defence system of fear: behaviour and neurocircuitry. Neurophysiol. Clin. Neurophysiol. 33, 55–66. While this can mean an increased likelihood of immediate survival, it also leads to reduced food and water intake.Chelini, M.-C., Willemart, R.H., Hebets, E.A., 2009. Costs and benefits of freezing behaviour in the harvestman Eumesosoma roeweri (Arachnida, Opiliones). Behav. Processes 82, 153–159.
Bobbing
To deflect attacks and enhance escape, long-legged species – commonly known as daddy long-legs – from the Eupnoi suborder, use two mechanisms. One is bobbing, for which these particular individuals bounce their bodies. It potentially serves to confuse and deflect any identification of the exact location of their bodies.Field, L.H., Glasgow, S., 2001. The Biology of Wetas, King Crickets and Their Allies. CABIHolmberg, R.G., Angerilli, N.P.D., LaCasse, L.J., 1984. Overwintering Aggregations of Leiobunum paessleri in Caves and Mines (Arachnida, Opiliones). J. Arachnol. 12, 195–204. This can be a deceiving mechanism to avoid predation when they are in a large aggregation of individuals, which are all trembling at the same time.Escalante, I., Albín, A., Aisenberg, A., 2013. Lacking sensory (rather than locomotive) legs affects locomotion but not food detection in the harvestman Holmbergiana weyenberghi. Can. J. Zool. 91, 726–731. Cellar spiders (Pholcidae) that are commonly mistaken for daddy long-legs (Opiliones) also exhibit this behavior when their webs are disturbed or even during courtship.Huber, B.A., Eberhard, W.G., 1997. Courtship, copulation, and genital mechanics in Physocyclus globosus (Araneae, Pholcidae). Can. J. Zool. 75, 905–918.
Autotomy
Autotomy is the voluntary amputation of an appendage and is employed to escape when restrained by a predator.Domínguez, M., Escalante, I., Carrasco-Rueda, F., Figuerola-Hernández, C.E., Marta Ayup, M., Umaña, M.N., Ramos, D., González-Zamora, A., Brizuela, C., Delgado, W., Pacheco-Esquivel, J., 2016. Losing legs and walking hard: effects of autotomy and different substrates in the locomotion of harvestmen in the genus Prionostemma. J. Arachnol. 44, 76–82.Fleming, P.A., Muller, D., Bateman, P.W., 2007. Leave it all behind: a taxonomic perspective of autotomy in invertebrates. Biological Reviews.Roth, V.D., Roth, B.M., 1984. review of appendotomy in spiders and other arachnids. Bull.-Br. Arachnol. Soc.Mattoni, C.I., García Hernández, S., Botero-Trujillo, R., Ochoa, J.A., Ojanguren-Affilastro, A.A., Outeda-Jorge, S., Pinto-da-Rocha, R. and Yamaguti, H.Y., 2001. Perder la cola o la vida. In Primer caso de autotomía en escorpiones (Scorpiones: Buthidae). III Congreso Latinoamericano de Aracnología, Memorias y Resúmenes (pp. 83–84). Eupnoi individuals, more specifically sclerosomatid harvestmen, commonly use this strategy in response to being captured.Houghton, J.E., Townsend, V.R., Proud, D.N., 2011. The Ecological Significance of Leg Autotomy for Climbing Temperate Species of Harvestmen (Arachnida, Opiliones, Sclerosomatidae). Southeast. Nat. 10, 579–590.Guffey, C., 1998. Leg Autotomy and Its Potential Fitness Costs for Two Species of Harvestmen (Arachnida, Opiliones). J. Arachnol. 26, 296–302. This strategy can be costly because harvestmen do not regenerate their legs, and leg loss reduces locomotion, speed, climbing ability, sensory perception, food detection, and territoriality.Macias-Ordonez, R., 1998. The mating system of Leiobunum vittatum Say 1821 (Arachnida: Opiliones: Palpatores): Resource defense polygyny in the striped harvestman.
Fleeing
Individuals that are able to detect potential threats can flee rapidly from attack. This is seen with multiple long-legged species in the Leiobunum clade that either drop and run, or drop and remain motionless.Machado, G., Raimundo, R.L.G., Oliveira, P.S., 2000. Daily activity schedule, gregariousness, and defensive behaviour in the Neotropical harvestman Goniosoma longipes (Opiliones: Gonyleptidae): Journal of Natural History: Vol 34, No 4. This is also seen when disturbing an aggregation of multiple individuals, where they all scatter.
Stridulation
Multiple species within the Laniatores and Dyspnoi possess stridulation organs – body parts that can be rubbed together to generate sound – which are used as intraspecific communication and have also been shown to be used as a second line of defense when restrained by a predator.
Retaliation
Armored harvestmen in Laniatores can often use their modified morphology as weapons.Dias, B.C., Willemart, R.H., 2013. The effectiveness of post-contact defenses in a prey with no pre-contact detection. Zoology 116, 168–174.Segovia, J.M.G., Del-Claro, K., Willemart, R.H., 2015. Defences of a Neotropical harvestman against different levels of threat by the recluse spider. Behaviour 152, 757–773. Many have spines on their pedipalps, back legs, or bodies.Eisner, T., Eisner, M., Siegler, M., 2005. Secret Weapons: Defenses of Insects, Spiders, Scorpions, and Other Many-legged Creatures. Harvard University Press. By pinching with their chelicerae and pedipalps, they can cause harm to a potential predator. This has been proven to increase survival against recluse spiders by causing injury, allowing the harvestman to escape from predation.
Chemical
Harvestmen are well known for being chemically protected. They exude strongly odored secretions from their scent glands, called ,Shultz, J.W., Pinto-da-Rocha, R., 2007. Morphology and functional anatomy. Harvest. Biol. Opiliones Harv. Univ. Press Camb. Mass. Lond. Engl. 14–61. that act as a shield against predators; this creates a strong and unpleasant taste, which is often their most effective defense. In Cyphophthalmi the scent glands release naphthoquinones, chloro-naphthoquinones and aliphatic , Insidiatores use nitrogen-containing substances, terpenes, aliphatic ketones, and Phenols, while Grassatores use alkylated phenolics and benzoquinones, and Palpatores use substances like naphthoquinones, methyl- and ethyl-ketones. A Novel Class of Defensive Compounds in Harvestmen: Hydroxy-γ-Lactones from the Phalangiid Egaenus convexus These secretions have successfully protected the harvestmen against wandering spiders (Wandering spider), wolf spiders (Lycosidae) and Formica exsectoides ants. However, these chemical irritants are not able to prevent four species of harvestmen being preyed upon by the black scorpion Bothriurus bonariensis (Bothriuridae). These secretions contain multiple volatile compounds that vary among individuals and clades.Gnaspini, P., Rodrigues, G.S., 2011. Comparative study of the morphology of the gland opening area among Grassatores harvestmen (Arachnida, Opiliones, Laniatores)of Zoological Systematics and Evolutionary Research.Hara, M. R., Gnaspini, P., 2003. Comparative study of the defensive behavior and morphology of the gland opening area among harvestmen (Arachnida, Opiliones, Gonyleptidae) under a phylogenetic perspective.Shear, W. A., Jones, T. H., Guidry, H. M., Derkarabetian, S., Richart, C. H., Minor, M., Lewis, J. J., 2014. Chemical defenses in the opilionid infraorder Insidiatores: divergence in chemical defenses between Triaenonychidae and Travunioidea and within travunioid harvestmen (Opiliones) from eastern and western North America | Journal of Arachnology.
Endangered status
All troglobitic species (of all animal taxa) are considered to be at least threatened in Brazil. Four species of Opiliones are on the Brazilian national list of endangered species, all of them cave-dwelling: Giupponia chagasi, Iandumoema uai, Pachylospeleus strinatii and Spaeleoleptes spaeleus.
Misconception
(pincer-like) chelicerae typical of harvestmen (200× magnification); these chelicerae are homologous to chelicerae that take the form of fangs in spiders or chelae in the Solifugae.
Research
Harvestmen are a scientifically neglected group. Description of new taxa has always been dependent on the activity of a few dedicated taxonomists. Carl Friedrich Roewer described about a third (2,260) of today's known species from the 1910s to the 1950s, and published the landmark systematic work Die Weberknechte der Erde (Harvestmen of the World) in 1923, with descriptions of all species known to that time. Other important taxonomists in this field include:
Phylogeny
Harvestmen are ancient . Fossils from the Devonian Rhynie chert, 410 million years ago, already show characteristics like tracheae and sexual organs, indicating that the group has lived on land since that time. Despite being similar in appearance to, and often confused with, spiders, they are probably closely related to the , , and ; these four orders form the clade Dromopoda. The Opiliones have remained almost unchanged morphologically over a long period. Indeed, one species discovered in China, Mesobunus martensi, fossilized by fine-grained volcanic ash around 165 million years ago, is hardly discernible from modern-day harvestmen and has been placed in the extant family Sclerosomatidae.
Systematics
/ref>
Fossil record
Despite their long history, few harvestman fossils are known. This is mainly due to their delicate body structure and terrestrial habitat, making them unlikely to be found in sediments. As a consequence, most known fossils have been preserved within amber.
Paleozoic
The 410-million-year-old Eophalangium sheari is known from two specimens, one a female, the other a male. The female bears an ovipositor and is about long, whilst the male had a discernable penis. Whether both specimens belong to the same species is not definitely known. They have long legs, tracheae, and no median eyes. Together with the 305-million-year-old Hastocularis argus, it forms the suborder Tetrophthalmi, which was thought to form the sister group to Cyphophthalmi. However, recent reanalysis of harvestman phylogeny has shown that E. sheari and H. argus are in fact members of the suborder Eupnoi, after it was discovered that living daddy-longlegs have the same arrangement of eyes as the fossils.
Described species
Mesozoic
etc. Bartel et al, 2023 report "These new records bring the total number of Burmese amber laniatorean species to ten"
Cenozoic
Unless otherwise noted, all species are from the Eocene.
Etymology
The Swedish naturalist and arachnologist Carl Jakob Sundevall (1801–1875) honored the naturalist Martin Lister (1638–1712) by adopting Lister's term for this order, from Latin ("shepherd"), because these arachnids were known in Lister's days as ""; Lister characterized three species from England (although not formally describing them, being a pre-Linnaean work). Martin Lister's English Spiders, 1678. Ed. John Parker and Basil Hartley (1992). Colchester, Essex: Harley Books. pp. 26 & 30. (Translation of the Latin original, Tractatus de Araneis.)
Further internal navigation links
External links
|
|
