Algidia
{{Short description|Genus of harvester}}
{{Italic title}}
{{Automatic taxobox
|image = Hard Bodied Harvestman 01.jpg
|image_caption = Algidia sp,
|taxon = Algidia
|authority = Hogg, 1920
|subdivision = See text.
|subdivision_ranks = Species
}}
Algidia is a genus in the harvestman family Triaenonychidae.{{Cite web |title=ADW: Algidia: CLASSIFICATION |url=https://animaldiversity.org/accounts/Algidia/classification/ |access-date=2024-05-10 |website=animaldiversity.org}} It is endemic to New Zealand and currently includes 7 species and several subspecies.
Taxonomy
The genus Algidia was erected by Henry R. Hogg in 1920.{{Cite journal |last=Hogg |first=Henry Roughton |date=1920 |title=3. Some Australian Opiliones |url=https://www.wikidata.org/wiki/Q54743294 |journal=Proceedings of the Zoological Society of London |volume=90 |issue=1–2 |pages=31–48 |doi=10.1111/J.1469-7998.1920.TB07632.X}} The type species is Algidia cuspidata Hogg, 1920. Ray Forster initially considered Algidia to be a synonym of Adaeum{{Cite journal |last=Forster |first=Raymond Robert |date=1943-01-01 |title=The Genus Adaeum Karsch (= Algidia Hogg) in New Zealand, With Descriptions of New Species (Order Opiliones). |url=https://www.wikidata.org/wiki/Q89182725 |journal=Transactions and Proceedings of the Royal Society of New Zealand |language=English |volume=73 |pages=68–72}} but re-established Algidia when he revised the genus in his 1954 monograph on the New Zealand Laniatores.{{Cite journal |last=Forster |first=Raymond Robert |date=1954 |title=The New Zealand harvestmen (sub-order Laniatores) |url=https://www.wikidata.org/wiki/Q118225133 |journal=Canterbury Museum Bulletin |language=English |volume=2 |pages=1–329}}
The genus Algidia contains the following species and subspecies:
:* Algidia chiltoni Roewer, 1931
:** Algidia chiltoni chiltoni Roewer, 1931
:** Algidia chiltoni longispinosa Forster, 1954
:** Algidia chiltoni oconnori Forster, 1954
:* Algidia cuspidata Hogg, 1920 — type species
:** Algidia cuspidata cuspidata Hogg, 1920
:** Algidia cuspidata multispinosa Forster, 1954
:* Algidia homerica Forster, 1954
:* Algidia interrupta Forster, 1954
:** Algidia interrupta interrupta Forster, 1954
:** Algidia interrupta solatia Forster, 1954
:* Algidia marplesi Forster, 1954
:* Algidia nigriflavum (Loman, 1902)
:* Algidia viridata Forster, 1954
:** Algidia viridata bicolor Forster, 1954
:** Algidia viridata viridata Forster, 1954
Forster's revision includes a key to these taxa. Forster also incorporated this information in a larger key to New Zealand Opiliones published in two parts.{{Cite journal |last=Forster |first=Raymond Robert |date=1962-01-01 |title=A key to the New Zealand Harvestmen — part I |url=https://www.wikidata.org/wiki/Q121898505 |journal=Tuatara |volume=10 |issue=3 |pages=129–137}}{{Cite journal |last=Forster |first=Raymond Robert |date=1963-01-01 |title=A key to the New Zealand Harvestmen — part 2 |url=https://www.wikidata.org/wiki/Q121898596 |journal=Tuatara |volume=11 |issue=1 |pages=28–40}}
A 2025 phylogenetic analysis suggests there are four undescribed species.{{Cite journal |last=Frigyik |first=Ella |last2=Baker |first2=Caitlin M. |last3=Sirvid |first3=Philip John |last4=Derkarabetian |first4=Shahan |last5=Giribet |first5=Gonzalo |date=2025-02-03 |title=Tiny Hunters Along the Alpine Fault: Integrative Phylobiogeography Demonstrates High Geographic Structure in a Forest‐Dwelling Aotearoa Harvester Genus (Arachnida, Triaenonychidae: Algidia) |url=https://www.wikidata.org/wiki/Q134426284 |journal=Journal of Biogeography |language=English |volume=52 |issue=5 |doi=10.1111/JBI.15097}}
General appearance
Algidia has a row of prominent tubercles (cone-shaped protuberances) on the forward edge of the carapace. The eyemound (a raised, rounded structure with two eyes) bears several pustules (small, rounded protuberances) or small tubercles and is located a distance of approximately its own width behind the forward edge of the carapace. The dorsal (upper) surface has an open pattern of small pustules. This pattern is more complex in females. The free tergites (the rearmost segments) each have a row of strong tubercles. Pedipalps are larger in males than females. Colouring is typically in shades of brown, often with black markings. Algidia viridata and A. v. bicolor are exceptions as they are predominantly green.
Geographic range
Forster's 1954 revision recorded specimens from Auckland in the northern North Island to Fiordland in the lower South Island. More recent observations{{Cite web |title=iNaturalistNZ observations of Algidia |url=https://inaturalist.nz/observations?taxon_id=375413 |access-date=9 Aug 2023 |website=iNaturalistNZ}} have expanded the range to Northland and the Chatham Islands.
Phylogeny
Molecular studies using Sanger{{Cite journal |last1=Baker |first1=Caitlin M. |last2=Sheridan |first2=Kate |last3=Derkarabetian |first3=Shahan |last4=Pérez Gonzales |first4=Abel |last5=Giribet |first5=Gonzalo |date=2020 |title=Molecular phylogeny and biogeography of the temperate Gondwanan family Triaenonychidae (Opiliones: Laniatores) reveals pre-Gondwanan regionalisation, common vicariance, and rare dispersal |url=https://www.wikidata.org/wiki/Q121278182 |journal=Invertebrate Systematics |volume=34 |issue=6 |pages=637–660 |doi=10.1071/IS19069|url-access=subscription }} and ultra conserved element{{Cite journal |last1=Derkarabetian |first1=Shahan |last2=Baker |first2=Caitlin M. |last3=Hedin |first3=Marshal |last4=Prieto |first4=Carlos E. |last5=Giribet |first5=Gonzalo |date=2021-01-01 |title=Phylogenomic re-evaluation of Triaenonychoidea (Opiliones: Laniatores), and systematics of Triaenonychidae, including new families, genera and species |url=https://www.wikidata.org/wiki/Q110666617 |journal=Invertebrate Systematics |doi=10.1071/IS20047|url-access=subscription }}{{Cite journal |last1=Derkarabetian |first1=Shahan |last2=Baker |first2=Caitlin M. |last3=Giribet |first3=Gonzalo |date=2021-01-01 |title=Complex patterns of Gondwanan biogeography revealed in a dispersal-limited arachnid |url=https://www.wikidata.org/wiki/Q121305536 |journal=Journal of Biogeography |volume=48 |issue=6 |pages=1336–1352 |doi=10.1111/jbi.14080|url-access=subscription }} sequencing showed Algidia is part of a clade that includes the majority of New Zealand triaenonychid genera, as well as several genera from Australia, New Caledonia and South America. Algidia appears to have diverged from other genera during the Cretaceous or early Tertiary period. It is most closely related to Prasma and Triregia from New Zealand, and Diaenobunus and Triconobunus from New Caledonia.
A 2025 study shows that geological events including the formation of the Southern Alps, the Oligocene Marine Transgression and glaciation have influenced diversity and species distributions within this genus.