Leiobunum
Leiobunum is a genus of the harvestman family Sclerosomatidae with more than 100 described species. Contrary to popular belief, they are not spiders, although they share a resemblance. They are arachnids, in the order Opiliones, harvestmen. Species in Leiobunum tend to have relatively long legs compared with other harvestmen, and some species are gregarious.
Taxonomy
The genus was first described by Carl Ludwig Koch in 1798. The type species is Phalangium rotundum which became Leiobunum rotundum.Species
Leiobunum annulipes Banks, 1909 Leiobunum aldrichi Leiobunum alvarezi Goodnight & Goodnight, 1945 Leiobunum anatolicum Roewer, 1957 Leiobunum annulatum Walker, 1930 Leiobunum apenninicum Leiobunum aurugineum Crosby & Bishop, 1924 Leiobunum bicolor Leiobunum bifrons Roewer, 1957 Leiobunum bimaculatum Banks, 1893 Leiobunum biseriatum Roewer, 1910 Leiobunum blackwalli Meade, 1861 Leiobunum bogerti Goodnight & Goodnight, 1942 Leiobunum bolivari Goodnight & Goodnight, 1945 Leiobunum bracchiolum C.R.McGhee, 1977 Leiobunum bruchi Mello-Leitão, 1933 Leiobunum brunnea Walker, 1930 Leiobunum calcar Leiobunum caporiacci Roewer, 1957 Leiobunum coccineum Simon, 1878 Leiobunum colimae Goodnight & Goodnight, 1945 Leiobunum consimile Banks, 1900 Leiobunum crassipalpe Banks, 1909 Leiobunum cretatum Crosby & Bishop, 1924 Leiobunum cupreum Simon, 1878 Leiobunum curvipalpi Roewer, 1910 Leiobunum cypricum Roewer, 1957 Leiobunum davisi Leiobunum defectivum Rambla, 1959 Leiobunum denticulatum Banks, 1900 Leiobunum depressum Davis, 1934 Leiobunum desertum Goodnight & Goodnight, 1944 Leiobunum dromedarium F.O.Pickard-Cambridge, 1904 Leiobunum ephippiatum Roewer, 1910 Leiobunum escondidum Chamberlin, 1925 Leiobunum euserratipalpe Ingianni, McGhee & Shultz, 2011Leiobunum exillipes Leiobunum flavum Banks, 1894 Leiobunum formosum Leiobunum fuscum Roewer, 1910 Leiobunum ghigii Caporiacco, 1929 Leiobunum globosum Suzuki, 1953 Leiobunum glabrum L.Koch, 1869 Leiobunum gordoni Goodnight & Goodnight, 1945 Leiobunum gracile Thorell, 1876Leiobunum gruberi Karaman, 1996 Leiobunum guerreoensis Goodnight & Goodnight, 1946 Leiobunum hedini Roewer, 1936 Leiobunum heinrichi Roewer, 1957 Leiobunum hiasai Suzuki, 1976 Leiobunum hikocola Suzuki, 1966 Leiobunum hiraiwai Leiobunum hoffmani Ingianni, McGhee and Shultz, 2011 Leiobunum holtae McGhee, 1977 Leiobunum hongkongium Roewer, 1957 Leiobunum hoogstraali Goodnight & Goodnight, 1942 Leiobunum knighti Goodnight & Goodnight, 1942- † Leiobunum inclusum Roewer, 1939 Leiobunum insignitum Roewer, 1910 Leiobunum insulare Roewer, 1957 Leiobunum ischionotatum Leiobunum japanense Leiobunum japonicum Leiobunum kohyai Suzuki, 1953 Leiobunum leiopenis Davis, 1934 Leiobunum limbatum L.Koch, 1861 Leiobunum lindbergi Roewer, 1959Leiobunum longipes Weed, 1890Leiobunum lusitanicum Roewer, 1923 Leiobunum maculosus Leiobunum manubriatum Leiobunum marmoratum F.O.Pickard-Cambridge, 1904 Leiobunum maximum Roewer, 1910Leiobunum mesopunctatum Goodnight & Goodnight, 1942 Leiobunum metallicum Roewer, 1932 Leiobunum mexicanum Banks, 1898 Leiobunum montanum Suzuki, 1953Leiobunum nigrigenum Goodnight & Goodnight, 1945 Leiobunum nigripes Weed, 1887Leiobunum nigripalpe Leiobunum nigropalpi Leiobunum nycticorpum Goodnight & Goodnight, 1942 Leiobunum oharai N. Tsurusaki, 1991 Leiobunum oregonense C.J. Goodnight and M.L. Goodnight, 1943Leiobunum patzquarum Goodnight & Goodnight, 1942 Leiobunum peninsulare Davis, 1934 Leiobunum politum Weed, 1890 Leiobunum potanini Leiobunum potosum Goodnight & Goodnight, 1942 Leiobunum relictum Davis, 1934 Leiobunum religiosum Leiobunum roseum C.L.Koch, in Hahn & C.L.Koch 1848 Leiobunum rotundum Leiobunum royali Goodnight & Goodnight, 1946 Leiobunum rubrum Suzuki, 1966 Leiobunum rumelicum Silhavý, 1965 Leiobunum rupestre Leiobunum sadoense N. Tsurusaki, 1982
- † Leiobunum sarapum Menge, 1854 Leiobunum seriatum Simon, 1878 Leiobunum seriepunctatum Doleschall, 1852Leiobunum serratipalpe Roewer, 1910Leiobunum silum Shultz, 2018Leiobunum simplum Suzuki, 1976Leiobunum socialissimum C.L.Koch, 1873 Leiobunum soproniense Szalay, 1951Leiobunum speciosum Banks, 1900 Leiobunum subalpinum Komposch, 1998Leiobunum supracheliceralis Roewer, 1957Leiobunum tamanum Suzuki, 1958Leiobunum tascum Goodnight & Goodnight, 1945 Leiobunum tisciae Avram, 1968Leiobunum tohokuense Suzuki, 1976Leiobunum townsendi Weed, 1893 Leiobunum trimaculatum Goodnight & Goodnight, 1943 Leiobunum tsushimense Suzuki, 1976Leiobunum uxorium Leiobunum ventricosum Leiobunum veracruzensis Goodnight & Goodnight, 1947Leiobunum viridorsum Goodnight & Goodnight, 1942 Leiobunum verrucosum Leiobunum vittatum Leiobunum wegneri Silhavý, 1976Leiobunum zimmermani Roewer, 1952
Habitat
Leiobunum species are found inhabiting tree trunks, fences, and walls such as building walls and stone walls.Furthermore, aggregations of harvestmen have been found located on industrial sites, ledges of windows, beneath roof gutters, and brickstone oven walls. Alike habitats have been found in Germany where Leiobunum aggregates are seen residing on house walls, and in corners of shaded buildings. Negative phototaxis is believed to play a role in this, where they can avoid sunlight.
Diet
Leiobunum are considered to be omnivores with an ability for predation and scavenging. The primary prey for Leiobunum are invertebrates such as Oligochaeta, commonly known as earthworms. However, many smaller species of Leiobunum are not capable of attacking larger earthworms so they do not prey on them frequently, this indicates that they are also capable of scavenging on dead Earthworms as well. For many species, earthworms made up a majority of their diet composition, with Coleoptera being slightly less eaten. Due to the small size of Leiobunum, they are still capable of attacking much larger predators and often use it to their benefit. Aside from predation, they are also observed to consume blackberries as their main source of non-animal food. In addition to their scavenging on earthworms, they also are capable of scavenging on Ephemeroptera significantly larger than them.In order to feed, Leiobunum have an advantageous adaptation to go further off the ground to prevent any clashes with ground level competition for prey. Leiobunum does not only eat on other animals and fruits, they are also seen to feed on bird droppings therefore can be considered a detritivore and infrequently scavenging on grasshoppers.
Predators of ''Leiobunum''
Harvestman species are preyed upon by spiders, such as Araneus diadematus, Larinioides seriacatus, Marpissa mucosa, and Zygiella x-notata. For example, the body of a Leiobunum was gripped by the jaws of a Marpissa mucosa spider, while having its legs removed.Body form
The Leiobunum, under the order Opiliones, is commonly identified as 'daddy long-legs' or 'harvestmen'. Arachnids under the order Opiliones are considered the most frequently observed terrestrial arthropods, as they are easily recognized in numerous environments due to their distinctive appearances. True to their common name of 'daddy long-legs', a distinguishable morphological feature of the Leiobunum is their long legs. Like other arachnids, they have eight legs, with the second pair of legs typically being the longest, as these play a crucial role in sensing the environment rather than locomotion. Therefore, the second pair of legs are known as the 'sensory legs', while the remaining six are primarily used for locomotion.The Leiobunum displays sexual dimorphism between males and females, which can aid in identifying the different species of Leiobunum. In both sexes, the Leiobunum possesses two eyes, while some may have one or no eyes in special cases. Eye placements for the Leiobunum can vary, depending on different suborders, as the eyes can be located dorsally on the prosoma or the ocular tubercle. Additionally, there is a pale yellow longitudinal line between the eyes; if the eyes were on the ocular tubercle, this pale yellow longitudinal line would greatly contrast with the body's colouration. In terms of the body's colouration, the dorsal area of the abdomen shows a brownish-black colour along with darker striper in the middle, while the sides show a brighter colouration.
Male and female Leiobunum vary in terms of morphological characteristics. A male Leiobunum tends to be smaller in length and width and has a flattened, oval body structure with a microsculpture and a scutum parvum in its abdomen. Female Leiobunum are generally larger in length and width with an oval body raised in the abdomen. Male Leiobunum have a slender penis which is whitish in color and feebly sclerotized; the penis also contain strongly elongated glans. Female Leiobunum have a whitish ovipositor for their genital morphology which aids in reproduction; the ovipositor consists of 25–27 segments, with the first 15–17 segments containing two distinct pairs of bristles on the dorsal and ventral sides.
Sexual reproduction
Leiobunum reproduce sexually through intromission, with males having a true penis. A pregenital chamber that encloses the male and female reproductive structures is located in the ventral side of the abdomen, opening to the anterior just below the mouth. This chamber is surrounded by a genital operculum that functions similarly to a trap door through the articulation of a transverse hinge posterior to the abdomen. In males, the penis can be externally exposed in the anterior with the movement of protractor muscles that help evert the reproductive structure, which is made possible by the flexible pregenital chamber. Prior to intromission, the male will initiate mating by attempting to climb on top of the female and grabbing her pedipalps or legs to orient himself to directly face her. The male hooks his pedipalps around the base of the female's second pair of legs. In preparation of the copulatory phase, the penis is everted to make contact with – but not penetrate – the pregenital chamber of the female. Males will typically secrete a nuptial gift from their accessory glands located near his pregenital chamber opening. Male penetration into the female pregenital chamber marks the copulatory phase, followed by a change in body position where the males appear to "face up", resulting in insemination. Mating only last momentarily for a few seconds and do not exhibit courtship behavior before and after copulatory events.While there no courtship behaviours observed between male and female Leiobunum, pre-mating behaviours has been observed between males undergoing intraspecific combat for suitable mates. Egg-laying females are guarded by a male, until another competitor arrives to challenge the position, in which the winner takes precedence as the new guard.