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. 

See also...

A new species of Limonid Crane Fly from Eocene Baltic Amber.

The Limoniidae are a large group of small-to-medium sized Crane Flies, Tipuloidea, with coloured or patterned wings, which are sometimes shortened or otherwise reduced. There are over 11 000 extant species within the family Limoniidae, divided into four subfamilies, the Chioneinae, Dactylolabinae, Limnophilinae and Limoniinae, with phylogenetic analyses suggesting that the Dactylolabinae are likely to be the oldest group. All members of the subfamily Dactylolabinae are currently placed within a single genus, Dactylolabis, with living members divided into four subgenera, Bothrophorus, Coenolabis, Dactylolabis and Eudactylolabis. Of these subgenera only Dactylolabis has a fossil record, being known from Eocene Baltic Amber, with four extinct subgenera, Aurolabis, Eobothrophorus, Eolabis and Idiolabis also used to describe Baltic Amber species.

In a paper published in the journal Palaeontologica Electronica in January 2015, Iwona Kania of the Department of Environmental Biology at Rzeszów University and Wiesław Krzemiński of the Institute of Systematic and Evolution of Animals at the Polish Academy of Sciences describe a new species of Dactylolabis from Eocene Baltic Amber.

The new species is placed in the subgenus Idiolabis and given the specific name ryszardi, in honour of Ryszard Szadziewski, an expert on fossil and living flies. Dactylolabis (Idiolabis) ryszardi i described from a single male specimen 7.3 mm in length, with 9.76 mm wings.

Dactylolabis (Idiolabis) ryszardi, male specimen in lateral view. Kania & Krzemiński (2015).

The long-lived status of the subgenus Dactylolabis (Dactylolabis), with all other described subgenera being either modern or Eocene, has recently been questioned. A phylogenetic analysis carried out by Kania and Krzemiński suggests that all the described subgenera are indeed discreet evolutionary lineages (although some of the Eocene subgenera contain only a single species), though the Eocene and modern members of Dactylolabis (Dactylolabis) are not particularly closely related.

Kania and Krzemiński observe that while the Eocene forests of Fennoscandia, which produced the Baltic Amber, were a warm-forest environment with little seasonal variation, similar to forests found closer to the equator today, these forests covered a vast geographical range, extending a long way north-to-south and also containing a wide range of altitudinal variation. This suggests that these forests would have had a high number of different environments within them, as is the case with modern tropical forests, but that this ecological variation is hidden somewhat by the nature of the Baltic Amber deposits, which contain river-transported material carried from many different areas by the action of vast ancient waterways.

Modern members of the subgenus Dactylolabis (Dactylolabis) are widely distributed, and have are tolerant of a broad range of environments, while the other modern subgenera of Dactylolabis are much more limited, with more specialized environmental requirements. Kania and Krzemiński suggest that the same may have been the case in the Eocene, with subsequent environmental change wiping out the more specialized groups while the more tolerant Dactylolabis (Dactylolabis) survived. This scenario makes it highly likely that Dactylolabis (Dactylolabis) is in fact polyphyletic as well as morphologically conservative, with more specialized forms repeatedly arising from within this subgenus

See also…

Winter Crane Flies from the Middle Jurassic Jiulongshan Formation of Inner Mongolia.
Winter Crane Flies (Trichoceridae) are large True Flies (Diptera) with a (slightly erroneous) reputation for being tolerant of cold conditions. In fact a few species are capable of remaining active in winter, with some even mating and laying eggs beneath snow cover, but...

A Non-biting Midge from Late Eocene Ukrainian amber.
Non-biting Midges (Chironomidae) are small Flies closely related to the Biting Midges, Solitary Midges and Blackflies. They closely resemble Mosquitoes, but despite their appearance and relationships, they...


A new species of Axymyid Fly from the northwest United States.
Axymyids are medium sized, stout bodied, True Flies (Diptera) related to the Gnats, Midges, Mosquitoes and Crane Flies. They have a fossil record going beck to the Jurassic, but are rare today, with only six described species.

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