Douglassarachne acanthopoda: A spiney Arachnid from the Mazon Creek Fauna of Illinois.

The Late Carboniferous appears to have been a time of remarkable Arachnid diversity, with known fossils including long-established Arachnid groups such as the Scorpions and Harvestmen, as well as the first appearance of other groups such as the Spiders, Whip Spiders, Whip Scorpions, Tick Spiders, and Camel Spiders. In addition to these living groups, Carboniferous deposits have yielded fossils of a number of entirely extinct groups such as the Trigonotarbids, Phalangiotarbids, and Haptopods. A number of Carboniferous fossil 'Spiders' are also likely to represent extinct, non-Spider groups, as they do not possess spinneretes (silk-producing organs) which are considered to be the diagnostic organ for Spiders by modern Arachnologists. 

In a paper published in the Journal of Paleontology on 17 May 2024, Paul Selden of the Department of Geology at the University of Kansas, and the Natural History Museum in London, and Jason Dunlop of the Museum für Naturkunde at the Leibniz Institute for Evolution and Biodiversity Science, describe a new species of Arachnid from the Late Carboniferous Mazon Creek Fauna of Illinois.

The Mazon Creek Fossil-Lagerstätte produces a wide range of terrestrial and shallow-marine fossils preserved in ironstone concretions collected from the spoilheaps of coal strip mines around Braidwood in northeastern Illinois. These deposits have provided a valuable insight into the flora and fauna of the Late Carboniferous, including a wide range of Arachnids, with every known order found here, with the exception of the Haptopoda, which is known only from the Late Carboniferous of the UK. 

The new species is described from a single specimen which came from a concretion found in the 1980s by fossil hunter Bob Masek on the spoil heap of Pit 15 Northern Mine near Essex in Kankakee County, Illinois. Masek split the concretion by leaving it outside in water during the winter, which enables frost to enter natural cracks in the hard ironstone and widen them, then striking it with a hammer to get it to split along  a single plain. The specimen was acquired from Masek by David Douglass of the Prehistoric Life Museum, where it was displayed until 2023, when the importance of the fossil was realised, and it was donated to the Field Museum of Natural History in Chicago.

The new species is named Douglassarachne acanthopoda, where 'Douglassarachne' means 'Douglass's Arachnid' in honour of David Douglass for donating the fossil, and 'acanthopoda' means 'prickly legs' in reference to the numerous spines on the legs of the specimen.

Douglassarachne acanthopoda, holotype and only known specimen FMNH PE 91366. (1) Photograph of part; (2) explanatory drawing of part; (3) photograph of counterpart; (4) explanatory drawing of counterpart; 1–4, leg numbers; a t, anal tubercle; e t, eye tubercle; fe, femur; t, tergite. Scale bars are 5 mm. Seldon & Dunlop (2024).

Douglassarachne acanthopoda has a bodylength of about 15 mm, and a body roughly divided into two parts, interpreted as an anterior prosoma and a posterior segmented opisthosoma. The prosoma is covered by a subtriangular dorsal shield, which is divided, and has a slight anterior projection. The chelicerae and pedipalps cannot be seen. The legs are robust, and of roughly even length, with a notable covering of spines. The connection between the prosoma and the opisthosoma is broad, represented by only a slight narrowing of the body. The opisthosoma has at least eight visible tergites, and lacks any form of s spines or large tubercles, with the exception of what appears to be a terminal anal tubercle.

Douglassarachne acanthopoda, reconstruction of the possible appearance of the animal in life. Seldon & Dunlop (2024).

Douglassarachne acanthopoda does not clearly belong to any described order of Arachnids, living or extinct. The spiney legs of the species are similar to those seen in Armoured Harvestmen, Podoctidae, but there is no other indication of a close relationship, and spines have arisen numerous in numerous Arthropod groups as an anti-predation measure. 

Seldon and Dunlop note that there is a precedent for naming Carboniferous Arachnid orders from a single specimen, the Haptopoda having been described in this way, but decide against doing this, on the basis that the discovery of another specimen of Douglassarachne acanthopoda with preserved chelicerae and pedipalps might reveal a closer relationship to another Arachnid group than is currently obvious, and the need for a revision of the numerous Carboniferous 'Spiders' now thought not to belong to that group. For the time being they settle for assigning the new species tentatively to the clade Pantetrapulmonata, which united the extant Spiders, Whip Spiders, and Whip Scorpions, with the extinct Trigonotarbids.

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Larca boulderica: A new species of Pseudoscorpion from Colorado.

The Larcidae is a small family of Pseudoscorpions, comprising 15 species within a single genus, Larca, found in Europe and North America. In North America four species are widely distributed surface dwellers, while five are cave-dwelling species with very limited distributions in the southern United States, while in Europe a single species is widely distributed across northern Europe and four are found in caves in the Mediterranean region.

In a paper published in the journal ZooKeys on 25 April 2024, Mark Harvey of Collections & Research at the Western Australian Museum and the School of Biological Sciences at the University of Western Australia, and David Steinmann of the Department of Zoology at the Denver Museum of Nature & Science, describe a new species of Larca from Mallory Cave, Colorado. 

Mallory Cave is located on Dinosaur Mountain to the west of Boulder on the eastern edge of the Rocky Mountains. It comprises a single chamber approximately 25 m wide and 7 m deep, with a single entrance facing to the east. The cave has been gated since 2011 to protect a breeding colony of Townsend’s Big-eared Bats, Corynorhinus townsendii, the population of which had fallen to 10 individuals in 2008-9 and risen to over 60 by 2023. 

The new species is named Larca boulderica, where 'boulderica' refers to Boulder County, where the species was found. It is described from seven specimens (two male and five female) collected from Packrat nests within Mallory Cave in 2008 and 2009 after the Bats had left for the winter.

A specimen of Larca boulderica, in situ in Mallory Cave. Harvey & Steinmann (2024).

Specimens of Larca boulderica are yellowish brown in colour, with the legs and the genital region of females being paler. Male specimens are between 2.25 and 2.37 mm in length, while females are between 2.51 and 2.74 mm. The cuticle of these Pseudoscorpions is granulated. Venom apparatus are found on both fingers of the pedipalps (claws), with 30 teeth on the fixed fingers of both sexes, while the males have 29 teeth on the movable finger and the females have 28.

Larca boulderica, paratype female (DMNS): (7) body, dorsal view (8) body, ventral view. Harvey & Steinmann (2024).

The distribution of Larca is similar in both North America and Europe, with widely distributed, surface-dwelling species found northerly habitats, and cave dwelling species with limited ranges found in the southern part of the distribution of the genus. Harvey and Steinmann suggest that this is because caves serve as refugia during times of climate change, particularly in this case preserving cooler, moister environments in areas that have become significantly warmer and drier since the end of the Pleistocene. 

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A hitchhiking Pseudoscorpion from Chiapas Amber.

Phoresis is an interaction in which an Animal hitches a ride on another Animal purely for the purpose of transport. This is found in a variety of Animal groups, but is particularly common in Mites and Pseudoscorpions. Unusually for an Animal behaviour, phoresis has a fairly long fossil record, with the oldest known example being a Mite found attached to an early Orthopteran Insect from from the Carboniferous Tupo Formation of China, and the oldest known example involving a Pseudoscorpion coming from Cretaceous Burmese Amber.

In a paper published in the journal Historical Biology on 7 April 2024, Víctor Córdova-Tabares of the Universidad Autónoma del Estado de Morelos and the Departamento de Zoología at the Escuela Nacional de Ciencias Biológicas, Francisco Riquelme, also of the Universidad Autónoma del Estado de Morelos, and Gabriel Villegas-Guzmán, Javier Víctor, and Emilio Estrada Ruiz, also of the Departamento de Zoología at the Escuela Nacional de Ciencias Biológicas, describe an example of phoresis from Mexican Chiapas Amber, in which a Pseudoscorpion is attached to a Crane Fly.

Chiapas Amber comes from the Simojovel, Totolapa, and Estrella de Belén localities in the Chiapas Highlands of southern Mexico, with the Simojovel site being the main centre of commercial amber extraction. The amber comes from a series of limestone, sandstone, siltstone, shale, and lignite beds of Late Oligocene to Early Miocene age, referred to as either the Simojovel Formation or the La Quinta Formation. The amber here is thought to have derived from a type of Leguminous tree of the genus Hymenaea; resin-producing trees belonging to this genus are also thought to have been responsible for Dominican Amber, which is of approximately the same age as Chiapas Amber, and are still found today across the Neotropics. 

The Amber-Lagerstätte from Chiapas in southern Mexico: Simojovel, Totolapa, and Estrella de Belén, Late Oligocene to Early Miocene. Schematic map showing the location of the Montecristo mines in Simojovel. Córdova-Tabares et al. (2024).

The specimen described is a piece of amber from the Montecristo Mine at Simojoval in the Colección de Artrópodos Fósiles of the Escuela Nacional de Ciencias Biológicas. The Pseudoscorpion involved is assessed to belong to the genus Hysterochelifer, which has four extant species, but differs from these in the structure of its chelicerae. It is therefore assigned to a new species, Hysterochelifer manpauch, becoming the designated holotype of that species. The specific name 'manpauch' derives from the Tzotzil ‘man pauch’, meaning a person who works with amber.

Hysterochelifer manpauch. (A) Holotype CAF-1 (phoront) and CAF-2 (carrier), general view. (B) CAF-1 in dorsal view; (C) CAF-1 in a closer view. Legs in Roman numerals, abbreviations ab, abdomen; c, carapace; che, chelicera; gt, genitalia pa, patella. Córdova-Tabares et al. (2024).

The Pseudoscorpion is attached to the trochanter (second segment) of the foreleg of a Cranefly assigned to the species Trentepohlia immemorata, one of two species of this genus previously described from Chiapas Amber.

The Pseudoscorpion genus Hysterochelifer belongs to the family Cheliferidae, which is distinguished by having  a well-developed venom apparatus in both chelal fingers. The family dates back to the Middle Cretaceous, with the oldest specimen coming from Cenomanian Archingeay Amber, which comes from the Charente Maritime district of south-western France. A protonymph (hatchling) assigned to the Cheliferidae has previously been described from Chiapas Amber, but this is the first adult specimen. 

Pseudoscorpions attached as phoronts to other Insects have previously been described from both  Baltic and Dominican amber, most commonly targetting Dipterans (True Flies) or Wasps. Living Pseudoscorpions will attach to a variety of organisms, including Vertebrates such as Birds and Mammals, but generally prefer Insects or larger Arachnids, and in particular Beetles. Beetles tend to have fairly specific environmental requirements, as do Pseudoscorpions, so a Pseudoscorpion attaching to a Beetle has a good chance of being carried to a suitable new environment. Flies are more tolerant in their environmental needs, typically settling on a wide range of surfaces, making them less ideal carriers. 

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Pararoncus leonardi & Pararoncus taeyoungi: Two new species of Pseudoscorpion from South Korea.

Pseudoscorpions are a somewhat overlooked group in Korea, with only 25 species reported from the country, from twelve genera and seven families, which is likely to be a considerable underestimation of the total. The family Syarinidae, which contains 125 species and has a worldwide distribution, is known only from a single species in Korea, Pararoncus japonicus (which is also known from Japan). Pararoncus japonicus is also interesting in that it is widespread and found in leaf litter, whereas all other described species in the genus have very limited distributions, often within caves, with the exception of Pararoncus histrionicus, which was discovered 'taken at quarantine in Hawaii', originating from an unknown point in Japan.

In a paper published in the jounal Evolutionary Systematics on 2 April 2024, Kyung-Hoon Jeong of Seoul National University, the Species Diversity Research Division of the Korean National Institute of Biological Resources, and the Department of Agricultural Convergence Technologty and Laboratory of Insect Phylogenetics & Evolution at Jeonbuk National University, Danilo Harms of the Museum of Nature Hamburg, the Harry Butler Institute at Murdoch University, and the Australian Museum Research Institute, and Jung-Sun Yoo, also of the Species Diversity Research Division of the Korean National Institute of Biological Resources, describe two new species of Pararoncus from South Korea.

The first new species is named Pararoncus leonardi, in honour of basketball player Kawhi Leonard who has the longest wingspan in the American National Basketball Association. The species is described from six specimens, three male and three female, collected from moist leaf litter habitats on Mount Sobaek in the Sobaek Mountains of Chungcheongbuk Province, 741 m above sealevel, in April and May 2022.

Habitus of Pararoncus leonardi.: (A) Female holotype in dorsal view; (B) female holotype in ventral view; (C) male paratype, dorsal; (D) male paratype ventral. Jeong et al. (2024).

Specimens of Pararoncus leonardi are between 3.32 and 3.98 mm in length, and reddish browm in colour with paler abdomens and legs. Unusually for a the genus, all specimens have four well-developed, lensed eyes (most species of Pararoncus only have a two eyes). 

The second new species is named Pararoncus taeyoungi, where honours  the former Korean Basketball League player Tae Young Moon who has the longest wingspan ratio in the Korean Basketball League. This species is also described on the basis of six specimens, three male and three female, collected from leaf litter on Mount Bangtae in Gangwon Province, 621 m above sealevel, in October 2022.

Habitus of Pararoncus taeyoungi: (A) Female holotype in dorsal view; (B) female holotype in ventral view; (C) male paratype, dorsal; (D) male paratype, ventral. Jeong et al. (2024).

Specimens of Pararoncus taeyoungi range from 2.77 mm to 3.32 mm in length and reddish brown in colour with the abdomen and legs being lighter, and a dark brown rear margin to each abdomen segment. Like Pararoncus leonardi, Pararoncus taeyoungi has two pairs of well developed, lensed eyes; the two species are generally similar to one another, but Pararoncus taeyoungi is notably smaller, and the proportion of the tarsus to the rest of the leg is larger in Pararoncus leonardi.

Type localities of all Pararoncus species according to the World Pseudoscorpiones Catalog (2023). The two new species are represented by squares, circles indicate epigean species in Japan, and triangles indicate troglobitic species. Jeong et al. (2024).

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Scorpiops (Euscorpiops) krachan: A new species of Scorpion from Thailand.

The Scorpion genus Scorpiops comprises medium-sized, generally brown Scorpions found across South,  Southeast, and  East Asia.  The genus is generally split into several subgenera, although not all of these are accepted by all experts in the field, while some  Scorpion  specialists elevate some or all of the subgenera to genus level.

In a paper published in the journal Zootaxa on 6 March 2024, Wasin Nawanetiwong of the Department of Biology at Chulalongkorn University, Ondřej Košulič of the Department of Forest Protection and Wildlife Management at Mendel University in Brno, Natapot Warrit, also of Chulalongkorn University, Wilson Lourenço of the Muséum national d’Histoire naturelle, and Eric Ythier of BYG Taxa, describe a new species of Scorpiops from the Kaeng Krachan National Park in Phetchaburi Province, Thailand.

The new species is described on the basis of three male and one female specimens, all collected within the park. It is placed within the subgenus Euscorpiops, and given the specific name krachan, in reference to the national park.

Scorpiops (Euscorpiops) krachan. (A), (B) Male holotype, habitus, dorsal (A) and ventral (B) aspects. (C), (D) Female paratype, habitus, dorsal (C) and ventral (D) aspects. Scale bar is 1 cm. Nawanetiwong et al. (2024).

Male specimens of Scorpiops (Euscorpiops) krachan ranged from 21.7mm to 26.9 mm in length, while the female specimen measured 25.9 mm, small for the subgenus. These Scorpions are brownish yellow in colour, with the females being darker than the males. Males have notably longer pedipalps and chelae than the females. The carapace has a weakly granular texture.

Scorpiops (Euscorpiops) krachan, female with pre-juveniles (instar I). Nawanetiwong et al. (2024).

Members of the genus Scorpiops have been described from a wide range of forest types at altitudes of between 40 m and 1800 m above sealevel. Scorpiops (Euscorpiops) krachan is the second member of the genus to be reported in Phetchaburi Province, and is found in the Tenasserim Mountain Range, which is covered by rainforests. Specimens were found under rocks in a transitional zone between secondary and primary rainforest. Members of the genus Scorpiops are ambush predators, giving them a rather sedentary lifestyle, and therefore limited distribution potential, which leads to a high rate of  endemism within the genus.

Natural habitat of Scorpiops (Euscorpiops) krachan in Kaeng Krachan National Park, Phetchaburi Province, Thailand. Nawanetiwong et al. (2024).

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