Leiobunum rotundum 10 1024
Leiobunum rotundum (Latreille, 1798), female. Photo Copyright © Arachnologische Gesellschaft e.V. [1].









Leiobunum C.L. Koch, 1839 is a greatly diverse genus of sclerosomatids with 130 species distributed in the Holarctic.

Type speciesEdit

Phalangium rotundum Latreille, 1798 (by subsequent designation Simon, 1879) - now Leiobunum rotundum (Latreille, 1798).


[From the forthcoming Catalogue of the World Opiliones by AB Kury]:

Leiobunum C.L. Koch 1839c: 35; Davis 1934: 663 (diagn., keys to USA species); Suzuki 1976 [type species: Phalangium rotundum Latreille 1798, by subsequent designation of Simon (1879b)].
Liobunum Agassiz 1846: 203 [unjustified emendation for Leiobunum C.L. Koch, 1839]; Thorell 1876a: 465, 493; Simon 1879b: 172 (key to species); Banks 1894a: 41 (key to NY species); Banks 1894e: 162 (key to WA species); Tullgren 1906a: 210 (key to Swedish species); Lessert 1917: 10; Roewer 1923: 883 (diagn., key); Mello-Leitão 1938b: 319.
Lejobunum Doleschall 1852: 651 (incorrect subsequent spelling).
Leiobunus Meade 1855: 411 [unjustified emendation for Leiobunum C.L. Koch, 1839].
Forbesium Weed 1890: 915 [junior subjective synonym of Leiobunum C.L. Koch, 1839: implied by Weed (1893a: 538), first stated by Banks (1893b: 210); type species: Phalangium formosum Wood, 1868, by subsequent designation of Crawford (1992)].
Pseudoliobunum Müller 1914: 95 [junior subjective synonym of Leiobunum C.L. Koch, 1839 by Suzuki (1976); type species: Pseudoliobunum japanense Müller, 1914 by monotypy].
Metaliobunum Suzuki 1940b: 276 [junior subjective synonym of Leiobunum C.L. Koch, 1839 by Suzuki (1976); type species: Metaliobunum japonicum Suzuki 1940, by original designation].


Leiobunum from Greek λειος (smooth) + βουνος (mound). Gender neuter. Forbesium for Prof. S.A. Forbes. Gender neuter.


Leiobunum originally in family Opilionidae; transferred to the Phalangiidae by Meade (1855).

Type species designationEdit

C.L. Koch originally included 3 species in Leiobunum, without choosing one as type of the genus – L. rotundum, L. rupestre and L. roseum. Thorell (1876a) designated as type Opilio fasciatus Herbst 1798 (which he at the same time synonymized with Opilio hemisphaericus Herbst, 1799), but this designation is invalid because it did not refer to any of the 3 original species. A few years later, Simon (1879b) validly designated Phalangium rotundum Latreille 1798 as type.

Forbesium as a junior synonymEdit

“Although currently listed as a synonym, Forbesium will probably have to be resurrected for part of the decidedly heterogeneous American "Leiobunum." Therefore, it is important to designate a type species, which has not heretofore been done. Of the two originally included species, Phalangium formosum Wood is selected here as being more likely to represent a distinct genus; the other, Forbesium hyemale Weed, 1890 (Weed 1890: 916, pl. 31) has been considered a subspecies of Leiobunum ventricosum (Wood), possibly a true Leiobunum, by Weed (1893a: 539), Davis (1934), and others.” [Crawford 1992].


Four of the most widespread species belong to the recent named Leiobunum rupestre species group.

Central-North AmericaEdit

Central AmericaEdit






Additional images - GalleryEdit