A checklist of chiggers (Trombidiformes: Trombiculidae and Leeuwenhoekiidae) of Panama

An updated checklist of chiggers from the family Trombiculidae and Leeuwenhoekiidae is presented, with 81 species in 38 genera parasitizing different terrestrial vertebrate hosts in Panama. The depository for all Panamanian records, including new localities and host-associations records for the species Blankaartia sinnamaryi (Floch and Fauran, 1956), Eutrombicula tinami (Oudemans, 1910), Eutrombicula goeldii (Oudemans, 1910), Hooperella vesperuginis (Brennan and Jones, 1960), and Pseudoschoengastia bulbifera Brennan, 1960 were provided.


Introduction
The first chigger described from Panama was Odontacarus dentatus (Ewing, 1925), originally described as Trombicula dentata Ewing, 1925(Ewing 1925b. Eighteen years later, Fairchild (1943) published a list with eight species followed by Wharton and Fuller (1952) world list of chiggers, assigning five genera and ten species to Panama. In 1961, Brennan and Jones (1961b) described: Aniatrus Brennan and Jones, 1961; Polylopadium Brennan and Jones, 1961; and Vanidicus Brennan and Jones, 1961 and including description of 17 new species. Soon after, Brennan and Yunker (1966) compiled a catalog for Panama, which recorded 76 species organized in 29 genera. In contrast, a key of chigger genera prepared by Brennan and Goff (1977a), identified 87 genera for the Nearctic and Neotropical regions, with only 25 assigned to Panama.
Compared to other countries in South and Central America, only Venezuela has the most significant diversity of chiggers, having 136 species in 38 genera (Brennan and Reed 1975). Among the countries that have a great diversity in this region with a compiled checklist were Brazil (63 species -Jacinavicius et al. 2018), Chile (25 species -de Silva-de la Fuente et al. 2020), and Peru (37 species -Brennan and Jones 1961) stand out, but still having a smaller number of species of chiggers when compared to Panama or Venezuela.
Here, we provide an updated checklist of Panamanian chiggers, the data on the distribution of these chiggers outside the country, and also, we provided the most recent taxonomic positions for some of these chigger species, as well as, corrected some host names. Besides that, we included new host associations and locality records for five species of chiggers.

Material and methods
The checklist is arranged in alphabetical order, following the format proposed by Jacinavicius et al. (2018), starting with: Genus -valid name of the genus, author, date, and page; Species -valid name of the species, author, date, page, type locality, type host, and type depository, in parenthesis are the typifications. The list below are the abbreviations of the Collections/Institutes used in this checklist: • AMNH USA, New York, American Museum of National History; The type locality is updated to the present day, as well as, it is as accurate as possible, for more details and old names of these localities, look for the original description, which is placed right after the type locality of each species.
All records in the "Panama records" section, were taken from literature. In some of these studies, the host species have not been separated by locality. So, for these cases, we also chose not to separate species by locality, followed by the new records for the country, when available.
The new records are based on the material deposited in the IBSP collection. When the species were also reported outside Panamanian territory, they were registered in the section "Other records". Dissertations and theses were not considered in this checklist. The "type depository" section is based on literature, either by the original description or by type catalogs such as those made by Hernandes et al. (2011) and Bassini-Silva et al. (2021). Besides that, according the type catalog made by Bassini-Silva et al. (2021), the Bernice Pauahi Bishop Museum (BPBM) and Rocky Mountain Laboratory (RML) collections are now housed in the USNM. Then in the "type depository" section, USNM is considered the collection in which the specimens are deposited. For the hosts, we are using the update host-list made by Bassini-Silva et al. (2021).
The species Trombicula cavernarum Ewing, 1933 and Trombicula trifurca Ewing, 1933 were not considered in this checklist because only the post-larval stages are known. The species Colicus exhumatus Brennan, 1970 was also not considered in this checklist given the dubious identification made by Brennan (1970b), as well as Microtrombicula sturnirae Webb and Loomis, 1971 due the fact that there are no details of collection data recorded from Panama, possible misspelling listed in Webb and Loomis (1977). In these two cases, we decided to put the species as Species inquirenda. Regarding to the genera Trombicula and Euschoengastia, we keep the species with its original genus designation. For these species, a systematic review is needed, including types examination. Unfortunately, this is not the task of the present checklist.
Appendix 1 provides a list of Panamanian chiggers with their respective hosts and Appendix 2 provides a list of hosts with their respective chiggers' species.
Of the 81 chigger species, five were from new localities. Blankaartia sinnamaryi, P. bulbifera, and E. tinami, were new records from Barro Colorado Island (Panama Province). Hooperella vesperuginis was recorded from Coiba Island (Veraguas Province) for the first time. In addition, E. goeldii and E. tinami were recorded from Santa Rosa (Colón Province) for the first time along with an additional record of E. goeldii from the Metropolitan Natural Park, Panama City (Panama Province).
Of the 1710 terrestrial vertebrate species in Panama (IUCN, 2021), only 8% (144 species -five reptiles, 71 birds and 68 mammals), including humans, have been recorded as chigger hosts. Also, there are more 24 unidentified hosts (4 reptiles, 4 birds and 16 mammals) recorded. It is worth noting that there were no records of chiggers from Amphibia, and only three chigger species (E. alfreddugesi, E. goeldii, and P. bulbifera) were reported from reptiles in Panama. All other records were from the classes Aves and Mammalia species. Checklists are essential to understanding the biodiversity of a region and showing where future studies may be needed.