Category Archives: Arachnida

Biantes parvulus (Hirst)

Small Seychelles Harvestman (Biantes parvulus)

The Small Seychelles Harvestman was described in 1911; it is known to have inhabited the islands of Mahé, Praslin and Silhoutette in the Seychelles archipelago.

The species has a body length of about 0.6 cm (including the palpi); it is dark brown; the distal ends of the tibiae of the second- and fourth legs are white; the distal tarsal segment of the third and the distal end of the metatarsus and the tarsal segments of the fourth are also pale-colored; the remaining segments of the legs being dark brown in color. [1]

The Small Seychelles Harvestman was only ever found once on Praslin in 1908 and was last recorded from Mahé and Silhouette in 1972; it has never been found since and is likely extinct now.

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syn. Hinzuanius parvulus Hirst

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palp from the inner side

Depiction from: ‘ S. Hirst: The Araneae, Opiliones and Pseudoscorpiones. The Percy Sladen Trust Expedition to the Indian Ocean in 1905, under the leadership of Mr. J. Stanley Gardiner, M.A. Vol 3. No. XVIII. Transactions of the Linnean Society of London. Second Series. Vol. 14. Zoology.: 379-395. 1910-1912’

(not in copyright)

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References:

[1] S. Hirst: The Araneae, Opiliones and Pseudoscorpiones. The Percy Sladen Trust Expedition to the Indian Ocean in 1905, under the leadership of Mr. J. Stanley Gardiner, M.A. Vol 3. No. XVIII. Transactions of the Linnean Society of London. Second Series. Vol. 14. Zoology.: 379-395. 1910-1912

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edited: 28.02.2024

Neorhytidelasma conuropsis Mironov, Dabert & Ehrnsberger

Carolina Parakeet Feather Mite (Neorhytidelasma conuropsis)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Tetrablemmidae gen. & sp. ‘Raivavae’

Raivavaean Armored Spider (Tetrablemmidae gen. & sp.)

The family Tetrablemmidae is a rather small familiy of spiders that mainly occurs in southeast Asia.

This form is known from subfossil remains found on the island of Raivavae, Austral Islands.

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edited: 31.10.2020

Voraptus tenellus (Simon)

Mahe Miturgid Spider (Voraptus tenellus)

This spider species is known from two records, one from 1908 and another one from 1972, it has not been seen since.

The known habitats are heavily degraded due to invasion by introduced plant species and the species very likely is already extinct.

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edited: 27.04.2021

Chiasmalges carolinensis Mironov, Dabert & Ehrnsberger

Carolina Parakeet Chiasmalges Feather Mite (Chiasmalges carolinensis)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Lopharalichus beckeri Mironov, Dabert & Ehrnsberger

Becker’s Lopharalichus Feather Mite (Lopharalichus beckeri)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Orobatida gen. & sp. ‘Rapa Nui’

Rapa Nui Beetle Mite (Orobatida gen. & sp.)

This species is known from core samples that were collected from the lake in the Rano Kau volcano on Rapa Nui, it is known from three samples from depths of 11,05 to 10,3 m. [1]

The species appears to be extinct now.

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References:

[1] M. Horrocks; M. Marra; W. T. Baisden; J. Flenley; D. Feek; L. González Nualart; S. Haoa-Cardinali; T. Edmunds Gorman: Pollen, phytoliths, arthropods and high-resolution 14C sampling from Rano Kau, Easter Island: evidence for late Quaternary environments, ant (Formicidae) distributions and human activity. Journal of Paleolimnology 50(4): 417-432. 2013

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edited: 10.12.2018

Zalmoxis ferrugineus (Roewer)

Seychelles Zalmoxis Harvestman (Zalmoxis ferrugineus)

This species was described in 1912; it is, or maybe was, endemic to the Seychelles, the exact locality, however, is apparently not known.

The cephalothorax reaches a length of 0,5 cm, the legs reach lengths of 0,6 to 1 cm, they are covered with variable spikes; the species is generally rusty colored, except for the eyes which are black.

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References:

[1] C. Fr. Roewer: Die Familien der Assamiden und Phalangodiden der Opiliones-Laniatores. Archiv für Naturgeschichte 78(3): 1-244. 1912

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Depiction from: ‘C. Fr. Roewer: Die Familien der Assamiden und Phalangodiden der Opiliones-Laniatores. Archiv für Naturgeschichte 78(3): 1-244. 1912’

(public domain)

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edited: 26.04.2022

Hirstienus nanus (Hirst)

Small Mahe Harvestman (Hirstienus nanus)

The Small Mahe Harvestman was described in 1913; it was endemic to the island of Mahé in the Seychelles.

The species has not been seen since its discovery in 1908 and is thought to be extinct; unfortunately I have not been able so far to find any further information about this species.

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edited: 17.05.2022

Banksula californica Banks

Alabaster Cave Harvestman (Banksula californica)

The Alabaster Cave Harvestman was described in 1900; it is known only from a cave named Alabaster Cave in the El Dorado County of California, USA.

The species reached a body length of only about 0,2 cm, it also had quite short legs for a harvestman.

The only known locality has been destroyed by mining and has furthermore be sealed by concrete, thus making surveying impossible; the species might still be around but is, however, considered likely extinct.

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edited: 16.05.2022

Fainalges gracilitarsus Mironov, Dabert & Ehrnsberger

Feather Mite (Fainalges gracilitarsus)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Benoitodes caheni (Benoit)

Cahen’s Ground Spider (Benoitodes caheni)

This species was described in 1977, it is or was endemic to the island of Saint Helena, where it appears to have been restricted to the Prosperous Bay Plain at the eastern coast of the island.

The species is/was 1,2 cm long, it has/had a reddish brown carapace and a grey abdomen.

The habitat of Cahen’s Ground Spider is now inhabited by the Brown Widow Spider (Latrodectus geometricus C. L. Koch), that was introduced in 1967, and which probably outcompited the endemic spider. 

The species was not found during recent field studies in 2003 and 2005/06 and may indeed be extinct. [1][2]

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References:

[1] Philip Ashmole; Myrtle Ashmole: Guide to Invertebrates of Prosperous Bay Plain, St Helena and illustrated account of species found on the Eastern Arid Area (EAA), including Prosperous Bay Plain, Holdfast Tom and Horse Point Plain. Report for St Helena Government 2004
[2] Howard Mendel; Philip Ashmole; Myrtle Ashmole: Invertebrates of the Central Peaks and Peak Dale, St. Helena. Report for the St Helena National Trust, Jamestown 2008

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edited: 02.12.2018

Protonyssus proctorae Mironov, Dabert & Ehrnsberger

Feather Mite (Protonyssus proctorae)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Genoprotolichus simplex Mironov, Dabert & Ehrnsberger

(Genoprotolichus simplex)

This feather mite was described in 2005; it is known from an immature skin of a Carolina Parakeet (Conuropsis carolinensis (L.)) without further data that had been collected sometimes before 1869 and was subsequently found on other Carolina Parakeet skins as well.

The species was adapted to its single host, the Carolina Parakeet, and died out together with its host. [1]

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References:

[1] Serge V. Mironov; Jacek Dabert; Rainer Ehrnsberger: Six new feather mite species (Acari: Astigmata) from the carolina parakeet Conuropsis carolinensis (Psittaciformes: Psittacidae), an extinct parrot of North America. Journal of Natural History 39: 2257-2278. 2005

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edited: 24.08.2022

Centrobunus braueri Loman

Brauer’s Spiky Harvestman (Centrobunus braueri)  

This species from the island of Mahé, Seychelles was discovered in 1894 (described in 1902), it was never recorded again, and thus is considered most probably extinct.  

The genus contains only this one species.  

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ocularium (on the left) and right palpus (on the right)  

Depiction from ‘J. C. C. Loman: Neue aussereuropäische Opilioniden. Zoologische Jahrbücher. Abteilung für Systematik, Geographie und Biologie der Tiere 16: 163-216. 1902’  

(not in copyright)

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edited: 26.11.2018

Halarachne americana Banks

Caribbean Monk Seal Nasal Mite (Halarachne americana)  

The Caribbean Monk Seal Nasal Mite was a parasite, specialized to the now extinct Caribbean Monk Seal (Neomonachus tropicalis (Gray)) where they lived inside the respiratory tract of that seal species, their biology, however, is not fully understood yet.

The mites disappeared together with their host species when the Caribbean Monk Seal died out in the 1950s.

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This genus contains at least two additional species which are still alive, the Grey Seal Nasal Mite (Halarachne halichoeri Allman) and the Hawaiian Monk Seal Nasal Mite (Halarachne laysanae Furman & Dailey), both apparently restricted to their own single seal species host.  

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female

Depiction from: ‘Nathan Banks: A treatise on the Acarina, or mites. Proceedings of the United States National Museum 28: 1-114. 1905’  

(public domain)

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edited: 20.09.2020

Dicrogonatus gardineri (Warburton)

Gardiner’s Giant Mite (Dicrogonatus gardineri)

Gardiner’s Giant Mite was described in 1912 based on specimens that were found in 1909 on the island of Mahé in the Seychelles where it inhabited the native forests at higher elevations.

Male about 4 mm. in length, black-brown, not highly polished. Genital area in general design like that of H. longipes but with the prominences at its postero-lateral limits much more salient. Peritreme broadest in the middle and tapering to either end.
Legs moderately long and slender and only sparsely clothed with hairs; leg 1 with the tarso-metatarsus of the same colour as the rest of the animal and only slightly dilated, and with a fairly strong spur under the distal end of the patella; tarsi of legs 2, 3, and 4 with three terminal spurs, two being more or less dorsal and the third lateral on the external side, and small conical spur on the under surface towards the distal end – very small on leg 4.
Female about 4.5 mm., of the colour and general appearance of the male, but with the legs destitute of the patellar and infra-tarsal spurs. Genital area large, the median plate very broad, with sides almost rectilinear, and its anterior border a sinuous transverse line. Lateral plates very small and narrow; anterior plate very broad and shallow.
Two ♂ and two ♀, taken in the jungle, Mahé, at an elevation of over 1200 ft.
” [1]

The species was never seen again and is considered extinct.

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syn. Holothyrus gardineri Warburton

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Depiction from: ‘Cecil Warburton: The Acarina of the Seychelles. Transactions of the Linnean Society of London Ser. 2 Vol. 15: 349-360. 1912-1913’

(not in copyright)

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References:

[1] Cecil Warburton: The Acarina of the Seychelles. Transactions of the Linnean Society of London Ser. 2 Vol. 15: 349-360. 1912-1913

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edited: 19.08.2022

Orsonwelles torosus (Simon)

Waimea Sheat Weaver (Orsonwelles torosus)  

The Waimea Sheat Weaver is known from only a single, female specimen which was collected by R. C. L. Perkins, a famous British entomologist who is best known for its work on the invertebrate fauna of the Hawai’i Islands in the late 19th century.

This sole specimen is labeled only with the locality name of ‘Waimea’, a name that can be found on several of the Hawaiian Islands, however, it is quite possible that it refers to the Waimea area on the island of Kaua’i.

The Waimea Sheat Weaver has never been found again since and is now considered very likely extinct.  

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Specimens from the neighboring islands of Hawai’i, Maui, Moloka’i, and O’ahu, that once were assigned to this species, were subsequently identified as and described as distinct species. 

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References:  

[1] Gustavo Hormiga: Orsonwelles, a new genus of giant linyphiid spiders (Araneae) from the Hawaiian Islands. Invertebrate Systematics 16. 369-448. 2002  

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Depiction from: ‘Fauna Hawaiiensis; being the Land-Fauna of the Hawaiian Islands. by various Authors, 1899-1913. Cambridge [Eng.]: The University Press 1913’

(public domain)

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edited: 20.09.2020

Tetragnatha paschae Berland

Rapa Nui Long-legged Spider (Tetragnatha paschae)  

This enigmatic species was described in 1924 based on three (?) female specimens – no one has ever found similar spiders on Easter Island since.

Rosemay G. Gillespie, who is an expert for spiders, especially of the genus Tetragnatha, considered is possibly identical to the Large Long-legged Spider (Tetragnatha maxillosa Thorell) which originates from Asia and is now distributed almost worldwide. This species, however, could not be recorded during fieldstudies which took place in 2012, instead the Brown Long-legged Spider (Tetragnatha nitens (Audouin)), a species that originates from the Mediterranean, was found.

If the Rapa Nui Long-legged Spider turns out to have indeed been a distinct, endemic species, it is now most certainly extinct. [1] 

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References:  

[1] Darko Davor Cotoras Viedma: Colonization of the most isolated island on Earth: What is the origin of the spider Tetragnatha paschae? 2012  

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prosoma and left jaw claw  

Depiction from: ‘L. Berland: Araignées de l’ile de Pàques et des iles Juan Fernandez. In: Skottsberg, C. (Ed.): The Natural History of Juan Fernandez and Easter Island 3: 419-437. 1924’  

(not in copyright)

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edited: 31.10.2016

Cicurina wartoni Gertsch

Warton’s Cave Spider (Cicurina wartoni)  

Warton’s Cave Spider is a small, color- and eyeless spider that is known from only very few, female specimens, and whose sole natural habitat is a small cave, called Pickle Pit, in Travis County, Texas.  

This cave sits on private land, and the landowners have denied everyone, including researchers access to the cave, the cave entrance has furthermore been locked with a gate whose lock is now rusted and which can obviously not be opened anymore, hence the last record of the species was in the year 2001.  

A big threat to the cave spiders are introduced Red Fire Ants (Solenopsis invicta (Buren)), an aggressive and highly invasive species, with which the spiders have to compete for food.  

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No one knows if Warton’s Cave Spider still exists at all – however, if it does, its future very probably looks bleak.  

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edited: 31.10.2017