Harvestman The Biology Of Opiliones Classification

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Published online 2015 Nov 18. doi: 10.3897/zookeys.537.6073
PMID: 26798238

Order Opiliones Sundevall, 1833. Pp 112-114 In Zhang, Z.-Q. Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness. Zootaxa 3148: 1–237. Reference page.. Full article (PDF) Reference page. 2012: A synopsis of catalogs and checklists of harvestmen (Arachnida, Opiliones). I'm about half-way through the 'Opiliones Project' - this is a twitter-project devoted to sharing facts about Harvestmen (follow using the hashtag #OpilionesProject). Daddy longlegs: spider or harvestmen? A nice overview of the biology of the species was provided by Jackson & Brassington, in 1987 – their paper is a key source for. Classification of harvestmen - Cyphophthalmi, Laniatores, Palpatores, and the link to Opiliones Notes. Cave Spider, from Arthur's Pass webscape information. Info on a possibly endangered NZ harvestman species, with photo.

Associated Data

Supplementary Materials
zookeys.537.6073-treatment1.xml (35K)

Abstract

A new species of troglobitic harvestman, Iandumoemasmeagolsp. n., is described from Toca do Geraldo, Monjolos municipality, Minas Gerais state, Brazil. Iandumoemasmeagolsp. n. is distinguished from the other two species of the genus by four exclusive characteristics – dorsal scutum areas with conspicuous tubercles, enlarged retrolateral spiniform tubercle on the distal third of femur IV, eyes absent and the penial ventral process slender and of approximately the same length of the stylus. The species is the most highly modified in the genus and its distribution is restricted only to caves in that particular area of Minas Gerais state. The type locality is not inside a legally protected area, and there are anthropogenic impacts in its surroundings. Therefore, Iandumoemasmeagolsp. n. is vulnerable and it must be considered in future conservation projects.

Keywords: Endemism, troglobitic, limestone, Espinhaço Supergroup, Minas Gerais state

Introduction

The subterranean or hypogean fauna is ecologically categorized according to the degree of the populations’ dependence and specialization to that environment, as proposed by Schiner (1854) and modified by Racovitza (1907) (apudBarr and Holsinger 1985, Trajano 2012): trogloxenes, organisms which are regularly found in caves, but that periodically return to the surface to feed and often to reproduce; troglophiles, organisms that can complete their life-cycle in either environment; and troglobites, organisms restricted exclusively to caves. Troglobites have evolved isolated in a peculiar selective regime, distinct from their ancestrals’: total absence of light, a tendency to environmental stability, lack of primary production and low energy intake (Culver and Pipan 2009). In order to survive and effectively colonize the hypogean realm, subterranean species must reproduce, defend their territories and find food and mates in this environment, regardless of vision (Gibert and Deharveng 2001). Several specializations related to the life in subterranean environment have been reported in literature – the autapomorphies, called troglomorphisms (Christiansen 2012).

In caves, harvestmen are found near to or in association with organic matter deposits or spots, under blocks and rocks, on the walls, and on the ceiling, exhibiting solitary or gregarious behavior (Reddell 2012). To date, eight species of troglobitic harvestmen have been described in Brazil, belonging to the families Gonyleptidae Sundevall, 1833 (seven species; one Pachylospeleinae and six from Pachylinae subfamily) and Escadabiidae Kury and Pérez 2003 (one species), in addition to several troglophile and trogloxene representatives (Trajano and Bichuette 2009, Willemart and Taques 2013). At least six other undescribed species has been reported as restricted to subterranean environments (Hara and Pinto-da-Rocha 2008, Willemart and Taques 2013).

The gonyleptid genus IandumoemaPinto-da-Rocha 1996, comprises two strictly subterranean species (troglobitic) up to now: IandumoemauaiPinto-da-Rocha 1996 and IandumoemasetimapocuHara and Pinto-da-Rocha 2008. The genus belongs to the polyphyletic Pachylinae (Pinto-da-Rocha et al. 2014) and its distribution is restricted to northern Minas Gerais state (eastern Brazil): Iandumoemasetimapocu is endemic to only one cave (Lapa do Zu cave, municipality of Coração de Jesus) (Hara and Pinto-da-Rocha 2008) and Iandumoemauai is restricted to two caves (Gruta Olhos d’Água and Lapa do Cipó caves, municipality of Itacarambi) (Pinto-da-Rocha 1996, ).

A new cave species of Iandumoema is herein described, being the second troglobitic harvestman with no eyes for Brazil (the first being the GonyleptidaeGiupponiachagasi Perez and Kury 2002, from Serra do Ramalho karst area, Bahia state, northeastern Brazil). This record corroborates the hypothesis of an exclusively troglobitic genus.

Material and methods

Study area

Iandumoemasmeagol sp. n. is recorded from two caves from Monjolos region, Minas Gerais State, Brazil. This region is located in the central east part of the southern portion of the São Francisco Craton, Velhas river basin, with a mean altitude of approximately 600 meters, inserted in the Sete Lagoas Formation, Bambuí Group, which has a relief typical of karst carbonate regions (Stávale 2012, Guimarães 2012) (Figure (Figure1a).1a). Monjolos region is characterized by evident karst relief, marked by large limestone cliffs, karrens, dolines, sinks, and resurgences, representing the exokarst (Figure (Figure1b),1b), and subterranean watercourses, diverse speleothems and caves, representing the endokarst (Guimarães 2012). According to the Köppen-Geiger climatic classification, the region has a tropical climate with a dry season (Kottek et al. 2006) type Aw (Sá Junior et al. 2012), with mean annual temperatures ranging between 20 and 21 °C. The vegetation is dominated by plants of the ‘cerrado’ sensu strictu, cerrado fields, and seasonal forests (Guimarães 2012). However, the vegetation surrounding the cave is under anthropogenic actions, such as pasture and agricultural activities.

a map of the study area at Monjolos municipality, Minas Gerais state, Brazil b Karst relief of Monjolos regions c entrance of Toca do Geraldo cave, a limestone cave of Bambuí Geomorphological Unit.

Toca do Geraldo is a limestone cave which extends approximately 1.5 km, with one entrance in a crack (Figure (Figure1c)1c) and another in the ceiling and a subterranean stream, which extends at least 400 meters. The harvestmen were found on the wet walls and sometimes in the silt substrate, next to the drainage, always in the aphotic zone. This cave has guano piles and litter as main food source for other cave arthropods such as crickets, cockroaches, mites, etc. Because the perennial drainage, the humidity is high (higher than 70%), even during the dry season. Lapa do Santo Antonio is also a limestone cave ca. 4.6 km far from Toca do Geraldo and also possess a subterranean stream; however, is an impacted cave due uncontrolled visitation. This cave has ca. of 300 m of extension.

Methods

The type material were collected, fixed in 70% ethanol and examined under a stereomicroscope. Live specimens were collected to observe the coloration in vivo. We took photographs and length measurements using a Leica stereomicroscope (M205C). Methods and terminology follow Acosta et al. (2007). The pattern of the macrosetae of the penis follows Kury and Villarreal (2015). Coloration is based on specimens immersed in ethanol and living specimens. Abbreviations used in Table Table22 are: Tr = trochanter; Fe = femur; Pt = patella; Ti = tibia; Mt = metatarsus; Ta = tarsus. All measurements are in millimeters. The types are deposited in the Museu de Zoologia, Universidade de São Paulo, São Paulo (MZUSP) and Laboratório de Estudos Subterrâneos, Universidade Federal de São Carlos, São Carlos (LES/UFSCAR).

Table 2.

Iandumoemasmeagol sp. n., measurements (in mm) of appendages of male paratype (MZUSP 67947) and female paratype (LES/UFSCar 0006299; in parentheses).

TrFePtTiMtTaTotal
Leg I0.3 (0.4)3.9 (3.0)1.1 (0.8)2.9 (2.1)4.8 (3.5)2.5 (2.1)15.5 (11.9)
Leg II0.5 (0.3)8.1 (5.3)1.5 (1.3)6.8 (5.1)9.2 (6.1)6.9 (5.2)25.7 (23.3)
Leg III0.6 (0.3)5.4 (3.9)1.3 (0.8)3.1 (2.2)5.5 (4.1)2.3 (1.5)18.2 (12.8)
Leg IV1.1 (0.5)6.9 (5.5)2.0 (1.5)5.2 (3.8)7.4 (6.1)2.2 (2.3)24.8 (19.7)
Pedipalp0.6 (0.4)2.1 (1.5)0.9 (0.8)1.6 (1.1)---1.1 (0.9)6.3 (4.7)

In the natural habitat, through ad libitum method (), the behavior and spatial distribution were observed. On four occasions, the minimal abundance through visual census method (Krebs 1999) was recorded, covering an extension of 300 m. Measurements of temperature and air humidity were recorded through a thermo-hygrometer.

Results

Key for the male of Iandumoema

1Apophysis of coxa IV directed obliquely backwards (parallel to body main axis)2
Apophysis of coxa IV directed laterally (perpendicular to body main axis)Iandumoemauai
2Dorsal scutum areas with conspicuous tubercles (paramedian pair higher than wide), retrolateral trochanter IV with larger tubercle on apexIandumoemasmeagol sp. n.
Dorsal scutum areas with low tubercle (as heigh as wide), retrolateral trochanter IV without larger tubercle on apexIandumoemasetimapocu

Iandumoemasmeagolsp. n.

http://zoobank.org/AAFD82A9-FA5B-4A71-958A-1150951CB142

Drawing of Iandumoemasmeagol sp. n. Male (holotype): habitus, dorsal view showing tubercles.

Photography of Iandumoemasmeagol sp. n. Male (holotype): habitus, dorsal view.

Iandumoemasmeagol sp. n. Male (holotype): habitus, right lateral view.

Iandumoemasmeagol sp. n. Male (holotype): habitus, ventral view.

Iandumoemasmeagol sp. n. Male (holotype): right pedipalp, ventral view.

Iandumoemasmeagol sp. n. Male (holotype): right trochanter IV, dorsal view.

Iandumoemasmeagol sp. n. Male (holotype): right leg IV, dorsal view.

Iandumoemasmeagol sp. n. Male (holotype): right leg IV, ventral view.

Iandumoemasmeagol sp. n. Male (paratype, MZUSP 67947): distal part of penis, dorsal view.

Iandumoemasmeagol sp. n. Male (paratype, MZUSP 67947): distal part of penis, left lateral view.

Iandumoemasmeagol sp. n. Live male specimen foraging in its natural habitat, showing detail of the pale yellowish coloration.

Iandumoemasmeagol sp. n. Female (paratype, LES/UFSCar 6299): habitus, dorsal view.

Type material.

Male holotype, Brazil, Minas Gerais, Monjolos, Toca do Geraldo cave, S18°16'43.31', W44°06'10.96’, 08.VII.2014, R. Fonseca-Ferreira, M.E. Bichuette, I. Arnone and J.E. Gallão leg. (MZUSP 67946). Paratypes: same locality of holotype, 22.II.2014, Rafael Fonseca-Ferreira and B.G.O. do Monte leg., one male (LES/UFSCar 0006298); Brazil, Minas Gerais, Lapa do Santo Antônio cave, S18°19'07,65', W44°07'03.32’, 21.II.2014, Rafael Fonseca-Ferreira and B.G.O. do Monte leg., one female (LES/UFSCar 0006299); same locality of holotype, 22.II.2014, Rafael Fonseca-Ferreira and B.G.O. do Monte leg., two male (MZUSP 67947 and MZUSP 67948).

Etymology.

The specific epithet refers to the hobbit named Smeagol, created by J.R.R. Tolkien, being the original name of Gollum – the dweller of the caves located below the Misty Mountains of Middle-earth of the Lord of the Rings book.

Diagnosis.

Iandumoemasmeagol sp. n. can be distinguished from other Iandumoema species by the following exclusive characteristics: dorsal scutum areas with conspicuous tubercles (paramedian pair much higher than wide), enlarged retrolateral spiniform tubercle on the distal third of femur IV, eyes absent and the penial ventral process slender and of approximately the same length as the stylus – and by the combination of the following characters: four pairs of macrosetae on penial basal group A+B (six in Iandumoemauai), three or four pairs of macrosetae on penial distal group C (six pairs in Iandumoemauai); and the apex of the penial truncus narrower than ventral plate basal width (wider in Iandumoemauai), and the setae of male pedipalpal tibia ectally and mesally with IiIi (ectally with IiiIi and mesally with IiIi in Iandumoemasetimapocu). A more detailed comparison of morphological and meristic features of Iandumoema species are provided in Table Table11.

Table 1.

Comparative morphological and meristic data for the three Iandumoema species from Brazilian caves (adapted from Hara and Pinto-da-Rocha 2008).

CharactersIandumoemauai Pinto-da-Rocha, 1996Iandumoemasetimapocu Hara & Pinto-da-Rocha, 2008Iandumoemasmeagol sp. n.
Eyes conditionAt least twice the diameter of tubercles on carapaceSame or similar size of diameter of tubercles on carapaceAbsent
Setae on male pedipalpal tibiaEctally and mesally with IiIiEctally with IiiIi and mesally with IiIiEctally and mesally with IiIi
Direction of dorso-apical apophysis on male coxa IVBackwards and laterallyObliquely backwards, close to bodyObliquely backwards, close to body
Submedian prolateral apophysis on male trochanter IVAbsentPresentPresent
Large tubercles on dorsal male femur apexTwo (one prolaterally, the other retrolaterally)Three (two as in Iandumoemauai, plus a large median one)Two (one prodorsal and one median)
Number of pair of macrosetae on penial basal group (A+B)644
Number of pairs of macrosetae on penial distal group (C)343–4
Shape of penial ventral processShort and serrateShort and serrateSlender and approx. same length as stylus, not serrate
Apex of penial truncusWider than ventral plate basal widthNarrower than ventral plate basal widthNarrower than ventral plate basal width
Description.

Male: Dorsum (Figures (Figures2,2, ,3,3, ,4):4): Measurements (paratype MZSP-67947): Dorsal scutum length 3.6; prosoma length 1.7; prosoma width 2.1; opisthosoma maximum width 3.1. Measurements of legs provided in Table Table2.2. Frontal hump with five tubercles (paramedian pair largest), anterior margin of dorsal scutum with 4–5 tubercles on each side. Ocularium without eyes; with high upwardly directed spine, apex curved backwards. Each side of ocularium with 2-3 tubercles. Prosoma with 10 tubercles posterior to ocularium. Scutal area I divided, with three tubercles on each side; scutal area II with one transversal row of 6-7 tubercles; scutal areas III–IV each with seven tubercles, paramedian pair largest and pointed on all areas. Lateral margin of dorsal scutum with an external row of 21–24 tubercles from sulci I–IV and an internal one with 14–16 tubercles from sulci I–II. Posterior margin of dorsal scutum with 14 tubercles. Free tergite I with 11 tubercles; II with 12; III with 10 (three median larger). Anal operculum with an anterior row of seven tubercles and posterior part irregularly tuberculate.

Venter (Figure (Figure5):5): Coxa I with one median row of five anterior tubercles and four posterior tubercles; coxa II with 11 tubercles; coxa III with seven tubercles; coxa IV and stigmatic area irregularly tuberculate. Posterior margin of stigmatic area, free sternites, and anal opercle each with one row of tubercles.

Harvestman The Biology Of Opiliones Classification System

Chelicera: Segment I elongated, bulla poorly defined, with four tubercles. Fixed finger with four equally sized teeth on the edge; movable finger with five teeth.

Pedipalps (Figure (Figure6):6): Slightly elongated. Coxa smooth. Trochanter with two dorsal and two ventral (ventro-mesal largest) tubercles. Femur with one ventro-basal large followed by three small tubercles. Patella smooth; tibial and tarsal spination: ectal and mesal IiIi.

Legs (Figures (Figures7,7, ,8,8, ,9,9, Table Table2):2): Coxa I with two stout tubercles; II with one stout anterior tubercle, one median small and one stout posterior; III with two stout tubercles, one anterior fused with the posterior tubercle of coxa II and one posterior IV with scattered tubercles and with dorso-apical, slightly sigmoid, backwards-directed apophysis, with one retrolateral apical long apophysis (4× longer than wide). Trochanter I with two dorsal, one retrolateral and three ventral tubercles; II with four dorsal, two prolateral, one retrolateral and three ventral tubercles; III smooth dorsally, with three retrolateral and six ventral tubercles; IV dorsally smooth, with large basal prolateral submedian apophysis bearing one tubercle, and with four retrolateral (apical largest), and 12 small ventral tubercles. Femur–tibia III with small tubercles.

Femur IV straight, with two rows of irregular dorsal tubercles, two ventral rows of higher than others of same segment (twice as long as wide) tubercles on apex, one retrolateral row of irregular-sized tubercles, larger than other of same segment (third apical one largest), two enlarged dorso-apical tubercles (one prodorsal and one median). Patella IV with two ventral rows of tubercles, tuberculate on the sides, dorsally unarmed. Tibia IV with two rows of ventral tubercles of similar sizes. Basitarsus I of similar size as distitarsus. Tarsal segmentation: 6(3), 11(3), 6, 6.

Penis (paratype MZSP-67947, Figures Figures10,10, ,11):11): Ventral plate subrectangular, with distal margin straight and a slight median constriction on the sides. Macrosetae: distal group with 3-4 on each side (C1–C4), basal one (C4, absent in the right) half-length of other three distal setae (similar sized, curved apically); median pair of setae (D1) placed more internally than groups A–C; basal group in arch (lateral view), formed by A1–3 and B1 (ventralmost), similar in length. Glans sac enlarged in the middle, stylus long and thicker than ventral process shaft; ventral process of glans without serrate distal margin, slender than and as long as stylus; both stylus and ventral process with ventromedian small microsetae.

Coloration

(Figures (Figures3,3, ,12).12). Ethanol: Pale yellowish carapace with tip of tarsus and dorsal tibia whitish (Figure (Figure3).3). Live specimens show a carapace with lighter coloration compared to the same part in the preserved specimen (Figure (Figure1212).

Female (paratype, LES/UFSCar 0006299, Figure Figure13):13): Measurements: Dorsal scutum length 3.1; prosoma length 1.2; prosoma width 1.8; opisthosoma maximum width 2.4. Measurements of appendages are presented in Table Table2.2. Only characteristics different from those of males are mentioned. Anterior margin of dorsal scutum with six tubercles on each side. Scutal area I with 3–5 tubercles on each side; scutal area II with eight; scutal area III with seven; scutal area IV with seven tubercles. Posterior margin of dorsal scutum with 13 tubercles. Free tergite I with 17; II with 17; III with 11 tubercles. Coxa IV with a shorter prolateral apophysis (half as long) than in male; trochanter IV with basal and median apophyses half as long or less than in male; tubercles on legs smaller than in male; femur IV with two enlarged dorso-apical tubercles.

Relationships.

Iandumoemasmeagol sp. n. seems to be close related to Iandumoemasetimapocu based on number of macrosetae on penis, four pairs on group A+B (six in Iandumoemauai) and apex of truncus narrower than ventral plate basal width. The shape of male apophysis on coxa IV is similar in both species, being obliquely directed, as also the presence of a submedian prolateral apophysis on male trochanter IV. However, a cladistics analysis is necessary to reveal well-supported relationships among Iandumoema species.

Distribution and natural history.

The occurrence of Iandumoemasmeagol sp. n. in the limestone caves of Bambuí Group, more specifically in the boundaries of Serra do Espinhaço Plateau (Figure (Figure1)1) shows that this region must be the eastern boundary distribution of the genus, the quartzite and the high altitudes of Serra do Espinhaço being the possible barriers. The results show that the genus Iandumoema only occurs in the northern Minas Gerais state, occupying an area of ca. 8,000 km2, and is restricted to hypogean environments, being exclusive to caves. This distribution range corroborates those presented by Hara and Pinto-da-Rocha (2008). Most specimens were collected in the aphotic zone of Toca do Geraldo cave; and only one individual was recorded in the Lapa do Santo Antônio cave. The minimum distribution range for Iandumoemasmeagol sp. n. (or occurrence area) is of 4.6 km2. The specimen collected in the Lapa do Santo Antônio cave was on the rocky substrate, at the twilight zone and close to the entrance (less than 50 m away). In four visits at Toca do Geraldo, the opilionids were observed on the walls (rocky substrate) and few on the silt substrate, always close to water bodies (drainage or pools). Despite the observed guano piles (of hematophagous bats), not one individual was observed close to them. The adults show solitary habits; on one occasion, one individual was feeding in litter, apparently scavenging carcasses of invertebrates (Figure (Figure12).12). In two occasions, active juveniles were observed on the walls while the adults showed a behavior comparatively more sedentary. In the four occasions, a total of 14 individuals were observed including adults and juveniles, always close to the cave stream, showing a low abundance. Apparently, the cave does not have dry galleries and/or conduits, showing high relative humidity of the air (ca. 80%) and temperature amplitude between 22 and 24 °C.

Troglomorphisms and conservation remarks.

As a result of their faunistic singularities and high endemism, hypogean environments are considered fragile. Besides their unique faunistic composition, the singularity of cave habitats is related to the presence of relicts, many times represented by troglobitic species. observed this tendency in a small area (24 km2) located at Chapada Diamantina, northeastern Brazil (at least 23 troglobitic species, most of them relict ones). Troglobitic species have unique sets of autapomorphies, such as eyes and melanistic pigmentation reductions allied to other troglomorphisms, such as pedipalps elongation in opilionids and other arachnids. A possible endemism in a karst area, which is threatened, was observed for Iandumoemasmeagol sp. n. in addition to the accentuated autapomorphies. Projects for the installation of small hydroelectric dams and limestone extraction for cement production represent potential impacts on the immediate environment (M. E. Bichuette and R. Fonseca-Ferreira, pers. obs.). Moreover, the extent of occurrence area of the species (4.6 km2) allied to the deforestation in the cave surroundings must place this species in a threatened category considering the IUCN criteria (Vulnerable, VU or Endangered, EN). Long-term studies focusing population biology and distribution of Iandumoemasmeagol sp. n. are urgent and fundamental to establish an effective conservation policy, including the creation of protected area(s).

Supplementary Material

XML Treatment forIandumoemasmeagol:

Acknowledgements

We are greatly indebted to: the field team, B.G.O. do Monte, C.S. Fernandes, I. Arnone and J.E. Gallão; M.P. Bolfarini for preparing the drawing of male habitus; the Instituto Nacional de Ciência e Tecnologia (INCT) of Hymenoptera parasitoids in the southeast of Brazil for permission to use the stereomicroscope Leica DFC 295 and L.B. Fernandes (UFSCar technician) for capturing the images; A.T. Fushita for preparing the map of the study area. The field trips were funded by the Programa de Pós-graduação em Biologia Comparada (PPGBC/USP) and Programa de Pós-graduação em Ecologia e Recursos Naturais (PPGERN/UFSCAR). M.E. Bichuette has been funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 303715/2011-1), R. Pinto-da- Rocha has been funded by Fundação de Amparo à Pesquisa do Estado e São Paulo (FAPESP, 2012/02969-6 and 2013/50297-0), the National Science Foundation (NSF/DOB 1343578) and NASA. To Cibele Bragagnolo and Marcos Hara for the carefully revision on the first draft of the manuscript.

Notes

Citation

Pinto-da-Rocha R, Fonseca-Ferreira R, Bichuette ME (2015) A new highly specialized cave harvestman from Brazil and the first blind species of the genus: Iandumoema smeagol sp. n. (Arachnida, Opiliones, Gonyleptidae). ZooKeys 537: 79–95. doi: 10.3897/zookeys.537.6073

References

Opiliones
Temporal range: 410–0 MaEarly Devonian – Holocene
Hadrobunus grandis showing its body structure and long legs: one pair of eyes and broadly joined body tagma differentiate it from similar-looking arachnids
Scientific classification
Kingdom:Animalia
Phylum:Arthropoda
Subphylum:Chelicerata
Class:Arachnida
Order:Opiliones
Sundevall, 1833
Suborders
Diversity
5 suborders, > 6,650 species

The Opiliones (/ˌpɪliˈnz/ or /ɒˌpɪliˈnɛz/; formerly Phalangida) are an order of arachnidscolloquially known as harvestmen, harvesters, or daddy longlegs. As of April 2017, over 6,650 species of harvestmen have been discovered worldwide,[1] although the total number of extant species may exceed 10,000.[2] The order Opiliones includes five suborders: Cyphophthalmi, Eupnoi, Dyspnoi, Laniatores, and Tetrophthalmi, which were named in 2014.[3]

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 Rhynie cherts of Scotland, and 305-million-year-old rocks in France, which look surprisingly modern, indicating that their basic body shape developed very early on,[4] and, at least in some taxa, has changed little since that time.

Their phylogenetic position within the Arachnida is disputed; their closest relatives may be the mites (Acari) or the Novogenuata (the Scorpiones, Pseudoscorpiones, and Solifugae).[5] Although superficially similar to and often misidentified as spiders (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.

English speakers may colloquially refer to species of Opiliones as 'daddy longlegs' or 'granddaddy longlegs', but this name is also used for two other distantly related groups of arthropods, the crane flies of the family Tipulidae, and the cellar spiders of the family Pholcidae, most likely because of their similar appearance. Harvestmen are also referred to as 'shepherd spiders' in reference to how their unusually long legs reminded observers of the ways that some European shepherds used stilts to better observe their wandering flocks from a distance.[6]

  • 3Antipredator defenses
    • 3.1Primary defenses
    • 3.2Secondary defenses
  • 10Fossil record
    • 10.1Paleozoic

Description[edit]

Tropical harvestman (Pachyloidellus goliath)
North European harvestman (Leiobunum rotundum) body

The Opiliones are known for having exceptionally long legs relative to their body size; however, some species are short-legged. As in all Arachnida, the body in the Opiliones has two tagmata, the anteriorcephalothorax or prosoma, and the posterior 10-segmented abdomen or opisthosoma. The most easily discernible difference between harvestmen and spiders is that in harvestmen, the connection between the cephalothorax and abdomen is broad, so that the body appears to be a single oval structure. Other differences include the fact that Opiliones have no venom glands in their chelicerae and therefore pose no danger to humans.

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 scutum, 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 pedipalps and the first pair of legs.

Most Opiliones, except for Cyphophthalmi, have a single pair of 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 indicates that the eyes in Cyphophthalmi are not homologous to the eyes of other harvestmen.[7][8] However, some 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.[9]

A harvestman (a male Phalangium opilio), showing the almost fused arrangement of abdomen and cephalothorax that distinguishes these arachnids from spiders

Harvestmen have a pair of prosomatic defensive scent glands (ozopores) 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 male Opiliones have a penis, unlike other arachnids. All species lay eggs.

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 hypothesized to function as an evolutionary advantage by keeping the attention of a predator while the harvestman escapes.[2]

Typical body length does not exceed 7 mm (0.28 in), and some species are smaller than 1 mm, although the largest known species, Trogulus torosus (Trogulidae), grows as long as 22 mm (0.87 in).[2] The leg span of many species is much greater than the body length and sometimes exceeds 160 mm (6.3 in) and to 340 mm (13 in) in Southeast Asia.[10] Most species live for a year.

Behavior[edit]

Harvestman eating a skink tail
Protolophus sp. cleaning its legs
A male Phalangium opilio, showing the long legs and the tarsomeres (the many small segments making up the end of each leg)
Mites parasitising a harvestman
Gregarious behavior in Opiliones

Many species are omnivorous, eating primarily small insects and all kinds of plant material and fungi; some are scavengers, feeding upon dead organisms, bird dung, and other fecal material. Such a broad range is unusual in other 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 gregarines.[2]

Although parthenogenetic species do occur, most harvestmen reproduce sexually. Mating involves direct copulation, rather than the deposition of a spermatophore. 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.[11]

The females lay eggs from an ovipositor 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.[12] 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 instars to reach maturity, with most known species having six instars.[2]

Most species are nocturnal and colored in hues of brown, although a number of diurnal 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. Gregarious 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.[2]

Harvestmen clean their legs after eating by drawing each leg in turn through their jaws.

Antipredator defenses[edit]

Harvestman The Biology Of Opiliones Classification

Predators of harvestmen include a variety of animals, including some mammals[13][14] amphibians and arachnids like spiders[15][16] and scorpions.[17] Opiliones display a variety of primary and secondary defenses against predation,[18] ranging from morphological traits such as body armor to behavioral responses to chemical secretions.[19][20] Some of these defenses have been attributed and restricted to specific groups of harvestmen.[21]

Primary defenses[edit]

Primary defenses help the harvestmen avoid encountering a potential predator, and include crypsis, aposematism, and mimicry.

Crypsis[edit]

Particular patterns or color 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.[22] Darker colorations and patterns function as camouflage when they remain motionless.[23] Within the genus Leiobunum are multiple species with cryptic coloration that changes over ontogeny to match the microhabitat used at each life stage.[21][24] Many species have also been able to camouflage their bodies by covering with secretions and debris from the leaf litter found in their environments.[21][25] Some hard-bodied harvestmen have epizoiccyanobacteria and liverworts growing on their bodies that suggest potential benefits for camouflage against large backgrounds to avoid detection by diurnal predators.[26][27]

Aposematism and mimicry[edit]

Some harvestmen have elaborate and brightly colored patterns or appendages which contrast with the body coloration, potentially serving as an aposematic warning to potential predators.[21][28][29] This mechanism is thought to be commonly used during daylight, when they could be easily seen by any predators.

Other harvestmen may exhibit mimicry to resemble other species’ appearances. Some Gonyleptidae individuals that produce translucid secretions have orange markings on their carapaces. This may have an aposematic role by mimicking the coloration of glandular emissions of two other quinone-producing species.[28] Mimicry (Müllerian mimicry) occurring between Brazilian harvestmen that resemble others could be explained by convergent evolution.[21]

Secondary defenses[edit]

Secondary defenses allow for harvestmen to escape and survive from a predator after direct or indirect contact, including thanatosis, freezing, bobbing, autotomy, fleeing, stridulation, retaliation, and chemical secretions.

Thanatosis[edit]

Some animals respond to attacks by simulating an apparent death to avoid either detection or further attacks.[30] Arachnids such as spiders practice this mechanism when threatened or even to avoid being eaten by female spiders after mating.[31][32] Thanatosis is used as a second line of defense when detected by a potential predator and is commonly observed within the Dyspnoi and Laniatores suborders,[29] with individuals becoming rigid with legs either retracted or stretched.[33][34][35][36]

Freezing[edit]

Freezing – or the complete halt of movement – has been documented in the family Sclerosomatidae.[37] While this can mean an increased likelihood of immediate survival, it also leads to reduced food and water intake.[38]

Bobbing[edit]

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.[21][38][39][40] 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.[21][41] 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.[42]

Autotomy[edit]

Leiobunum vittatum missing a leg, possibly as a result of autotomy

Autotomy is the voluntarily amputation of an appendage, and is employed to escape when restrained by a predator.[43][44][45][46] Eupnoi individuals, more specifically sclerosomatid harvestmen, commonly use this strategy in response to being captured.[41][47][48] This strategy can be costly because harvestmen do not regenerate their legs,[21] and leg loss reduces locomotion, speed, climbing ability, sensory perception, food detection, and territoriality.[41][48][47][49]

Autotomized legs provide a further defense from predators because they can twitch for 60 seconds to an hour after detachment.[45] 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.[34]

Fleeing[edit]

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.[50] This is also seen when disturbing an aggregation of multiple individuals, where they all scatter.[21][41]

Stridulation[edit]

Multiple species within the Laniatores and Dyspnoi possess stridulating organs, 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.[29]

Retaliation[edit]

Armored harvestmen in Laniatores can often use their modified morphology as weapons.[15][51][52] Many have spines on their pedipalps, back legs, or bodies.[21][53] By pinching with their chelicerae and pedipalps, they can cause harm to a potential predator.[15] Also this has been proven to increase survival against recluse spiders by causing injury, allowing the harvestman to escape from predation.[52]

Chemical[edit]

Harvestmen are well known for being chemically protected. They exude strongly odored secretions from their scent glands, called ozopores,[21][23][28][35][54] that act as a shield against predators; this is the most effective defense they use which creates a strong and unpleasant taste.[51] These secretions have successfully protected the harvestmen against wandering spiders (Ctenidae),[15][16] wolf spiders (Lycosidae) and Formica exsectoides ants.[20] However, these chemical irritants are not able to prevent four species of harvestmen being preyed upon by the black scorpion Bothriurus bonariensis (Bothriuridae).[17] These secretions contain multiple volatile compounds that vary among individuals and clades.[55][56][57]

Endangered status[edit]

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.

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 Spanish 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.

Misconception[edit]

Chelate (pincer-like) chelicerae typical of harvestmen (200x magnification); these chelicerae are homologous to chelicerae that take the form of fangs in spiders or chelae in the Solifugae.

An urban legend claims that the harvestman is the most venomous animal in the world,[58] but 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 cranefly, which are both also called a 'daddy longlegs').[59] This is untrue on several counts. None of the known species of harvestmen has venom glands; their chelicerae are not hollowed fangs but grasping claws that are typically very small and not strong enough to break human skin.

Harvestman The Biology Of Opiliones Classification

Research[edit]

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:Pierre Latreille (18th century)Carl Ludwig Koch, Maximilian Perty (1830s-1850s)L. Koch, Tord Tamerlan Teodor Thorell (1860s-1870s)Eugène Simon, William Sørensen (1880s-1890s)James C. Cokendolpher, Raymond Forster, Jürgen Gruber, Reginald Frederick Lawrence, Jochen Martens, Cândido Firmino de Mello-Leitão (20th century)Gonzalo Giribet, Adriano Brilhante Kury, Tone Novak (21st century).

Since the 1990s, study of the biology and ecology of harvestmen has intensified, especially in South America.[2]

Phylogeny[edit]

Harvestmen are ancient arachnids. Fossils from the DevonianRhynie 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 scorpions, pseudoscorpions, and solifuges; these four orders form the clade Dromopoda. The Opiliones have remained almost unchanged morphologically over a long period.[2][4] 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.[60][61]

Etymology[edit]

The Swedish naturalist and arachnologist Carl Jakob Sundevall (1801–1875) honored the naturalist Martin Lister (1638–1712) by adopting Lister's term Opiliones for this order, known in Lister's days as 'harvest spiders' or 'shepherd spiders', from Latin opilio, 'shepherd'; Lister characterized three species from England (although not formally describing them, being a pre-Linnean work).[62]

Systematics[edit]

The interfamilial relationships within Opiliones are not yet fully resolved, although significant strides have been made in recent years to determine these relationships. The following list is a compilation of interfamilial relationships recovered from several recent phylogenetic studies, although the placement and even monophyly of several taxa are still in question.[63][64][65][66][67]

  • Suborder CyphophthalmiSimon 1879 (about 200 species)
    • Infraorder BoreophthalmiGiribet 2012
    • Family SironidaeSimon 1879
    • Family StylocellidaeHansen & Sørensen 1904
    • Infraorder ScopulophthalmiGiribet 2012
    • Family PettalidaeShear 1980
    • Infraorder SternophthalmiGiribet 2012
    • FamilyTroglosironidaeShear 1993
    • Superfamily OgoveoideaShear 1980
    • Family NeogoveidaeShear 1980
    • Family OgoveidaeShear 1980
  • Suborder EupnoiHansen & Sørensen 1904 (about 1,800 species)
    • Superfamily CaddoideaBanks 1892
    • Family CaddidaeBanks 1892
    • Superfamily PhalangioideaLatreille 1802
    • Family NeopilionidaeLawrence 1931
    • Family PhalangiidaeLatreille 1802
    • Family ProtolophidaeBanks 1893
    • Family SclerosomatidaeSimon 1879
  • Suborder DyspnoiHansen & Sørensen 1904 (about 400 species)
    • Superfamily AcropsopilionoideaRoewer 1923
    • Family AcropsopilionidaeRoewer 1923
    • Superfamily IschyropsalidoideaSimon 1879
    • Family IschyropsalididaeSimon 1879
    • Family SabaconidaeDresco 1970
    • Family TaracidaeSchönhofer 2013
    • Superfamily TroguloideaSundevall 1833
    • Family DicranolasmatidaeSimon 1879
    • Family NemastomatidaeSimon 1872
    • Family NipponopsalididaeMartens 1976
    • Family TrogulidaeSundevall 1833
  • Suborder LaniatoresThorell, 1876 (about 4,200 species)
    • Infraorder InsidiatoresLoman, 1900
    • Superfamily TravunioideaAbsolon & Kratochvil 1932
    • Family CladonychiidaeHadži 1935
    • Family CryptomastridaeDerkarabetian & Hedin 2018
    • Family ParanonychidaeBriggs 1971
    • Family TravuniidaeAbsolon & Kratochvil 1932
    • Superfamily TriaenonychoideaSørensen, 1886
    • Family SynthetonychiidaeForster 1954
    • Family TriaenonychidaeSørensen, 1886
    • Infraorder GrassatoresKury, 2002
    • Superfamily AssamioideaSørensen, 1884
    • Family AssamiidaeSørensen, 1884
    • Family PyramidopidaeSharma and Giribet, 2011
    • Superfamily EpedanoideaSørensen, 1886
    • Family EpedanidaeSørensen, 1886
    • Family PetrobunidaeSharma and Giribet, 2011
    • Family PodoctidaeRoewer, 1912
    • Family TithaeidaeSharma and Giribet, 2011
    • Superfamily GonyleptoideaSundevall, 1833
    • Family AgoristenidaeŠilhavý, 1973
    • Family CosmetidaeKoch, 1839
    • Family CranaidaeRoewer, 1913
    • Family CryptogeobiidaeKury, 2014
    • Family GerdesiidaeBragagnolo, 2015
    • Family GonyleptidaeSundevall, 1833
    • Family ManaosbiidaeRoewer, 1943
    • Family MetasarcidaeKury, 1994
    • Family NomoclastidaeRoewer, 1943
    • Family StygnidaeSimon, 1879
    • Family StygnopsidaeSørensen, 1932
    • Superfamily PhalangodoideaSimon, 1879
    • Family PhalangodidaeSimon, 1879
    • Superfamily SamooideaSørensen, 1886
    • Family BiantidaeThorell, 1889
    • Family SamoidaeSørensen, 1886
    • Family StygnommatidaeRoewer, 1923
    • Superfamily SandokanoideaÖzdikmen & Kury, 2007
    • Family SandokanidaeÖzdikmen & Kury, 2007
    • Superfamily ZalmoxoideaSørensen, 1886
    • Family EscadabiidaeKury & Pérez, 2003
    • Family FissiphalliidaeMartens, 1988
    • Family GuasiniidaeGonzalez-Sponga, 1997
    • Family IcaleptidaeKury & Pérez, 2002
    • Family KimulidaePérez González, Kury & Alonso-Zarazaga, 2007
    • Family ZalmoxidaeSørensen, 1886

The family Stygophalangiidae (one species, Stygophalangium karamani) from underground waters in North Macedonia is sometimes misplaced in the Phalangioidea. It is not a harvestman.

Fossil record[edit]

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.

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 MYA, during the Ordovician.[68]

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 million years ago (Mya).

Naturally, most finds are from comparatively recent times. More than 20 fossil species are known from the Cenozoic, three from the Mesozoic,[61] and at least seven from the Paleozoic.[69]

Paleozoic[edit]

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 10 mm (0.39 in) 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.[3][70]

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.[3][4] 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'.

Harvestman The Biology Of Opiliones Classification Pdf

Some fossils from the Permian are possibly harvestmen, but these are not well preserved.

Described species[edit]

  • Eophalangium sheariDunlop, 2004 (Tetrophthalmi) — Early Devonian (Rhynie, Scotland)
  • Brigantibunum listoniDunlop, 2005 (Eupnoi?) — Early Carboniferous (East Kirkton, Scotland)
  • Echinopustulus samuelnelsoniDunlop, 2004 (Dyspnoi?) — Upper Carboniferous (Western Missouri, U.S.)
  • Eotrogulus fayoliThevenin, 1901 (Dyspnoi: † Eotrogulidae) — Upper Carboniferous (Commentry, France)
  • Hastocularis argusGarwood, 2014 (Tetrophthalmi) — Upper Carboniferous (Montceau-les-Mines, France)
  • Kustarachne tenuipesScudder, 1890 (Eupnoi?) — Upper Carboniferous (Mazon Creek, U.S.)
  • Nemastomoides elaverisThevenin, 1901 (Dyspnoi: † Nemastomoididae) — Upper Carboniferous (Commentary, France)
  • Nemastomoides longipesPetrunkevitch, 1913 (Dyspnoi: † Nemastomoididae) — Upper Carboniferous (Mazon Creek, U.S.)

Mesozoic[edit]

Currently, no fossil harvestmen are known from the Triassic. So far, they are also absent from the Lower CretaceousCrato 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.[citation needed]

A fossil of Halitherses grimaldii, a long-legged Dyspnoi with large eyes, was found in Burmese amber dating from approximately 100 Mya. It has been suggested that this may be related to the Ortholasmatinae (Nemastomatidae).[71]

Harvestman The Biology Of Opiliones Classifications

Cenozoic[edit]

Unless otherwise noted, all species are from the Eocene.

  • Haupt, 1956 (Dyspnoi: Trogulidae) — Geiseltal, Germany
  • Philacarus hispaniolensis (Laniatores: Samoidae?) — Dominican amber
  • Kimula species (Laniatores: Kimulidae) — Dominican amber
  • Cokendolpher & Poinar, 1998 (Laniatores: Samoidae) — Dominican amber
  • (Eupnoi: Caddidae) — Baltic amber
  • (Koch & Berendt, 1854) (Eupnoi: Phalangiidae) — Baltic amber
  • (Eupnoi: Phalangiidae?) — Baltic amber
  • Cheiromachus coriaceusMenge, 1854 (Eupnoi: Phalangiidae?) — Baltic amber
  • (Eupnoi: Sclerosomatidae) — Baltic amber
  • (Dyspnoi: Nemastomatidae) — Baltic amber
  • (Dyspnoi: Nemastomatidae) — Baltic amber
  • (Dyspnoi: Nemastomatidae) — Baltic amber
  • (Dyspnoi: Sabaconidae) — Baltic amber
  • Petrunkevitchiana oculata(Petrunkevitch, 1922) (Eupnoi: Phalangioidea) — Florissant Fossil Beds National Monument, USA (Oligocene)
  • Proholoscotolemon nemastomoides (Laniatores: Cladonychiidae) — Baltic amber
  • (Cyphophthalmi: Sironidae) — Bitterfeld amber
  • Amauropilio atavus(Cockerell, 1907) (Eupnoi: Sclerosomatidae) — Florissant, USA (Oligocene)
  • Amauropilio lacoei (A. lawei?) (Petrunkevitch, 1922) — Florissant, USA (Oligocene)
  • Cokendolpher, 1987 (Laniatores: Samoidae) — Dominican amber
  • Phalangium species (Eupnoi: Phalangiidae) — near Rome, Italy (Quaternary)

References[edit]

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  2. ^ abcdefghGlauco Machado, Ricardo Pinto-da-Rocha & Gonzalo Giribet (2007). 'What are harvestmen?'. In Ricardo Pinto-da-Rocha, Glauco Machado & Gonzalo Giribet (ed.). Harvestmen: the Biology of Opiliones. Harvard University Press. pp. 1–13. ISBN978-0-674-02343-7.
  3. ^ abcGarwood, Russell J.; Sharma, Prashant P.; Dunlop, Jason A.; Giribet, Gonzalo (2014). 'A Paleozoic Stem Group to Mite Harvestmen Revealed through Integration of Phylogenetics and Development'. Current Biology. 24 (9): 1017–1023. doi:10.1016/j.cub.2014.03.039. PMID24726154. Retrieved April 17, 2014.
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  16. ^ abWillemart, R.H.; Pellegatti-Franco, F. (2006). 'The spider Enoploctenus cyclothorax (Araneae, Ctenidae) avoids preying on the harvestman Mischonyx cuspidatus (Opiliones, Gonyleptidae)'. J. Arachnol. 34 (3): 649–652. doi:10.1636/S05-70.1.
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External links[edit]

Wikimedia Commons has media related to Opiliones.
Wikispecies has information related to Opiliones
  • Joel Hallan's Biology Catalog (2005)
  • Harvestman: Order Opiliones Diagnostic photographs and information on North American harvestmen
  • Harvestman: Order Opiliones Diagnostic photographs and information on European harvestmen
  • University of Aberdeen: The Rhynie Chert Harvestmen (fossils)
  • National Museum page Classification of Opiliones A synoptic taxonomic arrangement of the order Opiliones, down to family-group level, including some photos of the families
  • Pocock, Reginald Innes (1911). 'Harvester' . Encyclopædia Britannica (11th ed.).
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