:Nihoa trapdoor spider
{{Short description|Species of spider}}
{{Speciesbox
| name = Nihoa trapdoor spider
| image = nihoa_spider.jpg
| image_caption = Artist's rendition
| taxon = Nihoa mahina
| authority = Churchill & Raven, 1992
}}
The Nihoa trapdoor spider (Nihoa mahina) is a species of trapdoor spider in the family of Barychelidae that occurs on the island of Nihoa, Hawaii in the northwestern area of the Hawaiian island chain. Its scientific name can be broken up into two parts, Nihoa which is not only its place of origin but the name of its genus, and mahina, which means 'moon' in the Hawaiian language. This could tie back to the fact that the species was discovered not only in the moonlight but also has fine silver hair, resembling its namesake. The species can also be distinguished by a pattern found on its dorsal and the absence of a second row of teeth. Burrows of trapdoor spiders can commonly be found by mangrove roots or near loose coral rubble. Before the 1980s, trapdoor spiders were not thought to exist in Hawaii. Upon their discovery, the genus was given the name Nihoa, because it was assumed not to exist elsewhere.{{Cite journal |last=Churchill |first=Tracey |last2=Raven |first2=Robert |title=Systematics of the intertidal trapdoor spider genus Idioctis (Mygalomorphae: Barychelidae) in the western Pacific with a new genus from the northeast |journal=Memoirs of Queensland Museum |volume=32 |issue=1 |pages=9-30}}
Taxonomy and classifications
Nihoa mahina is an arachnids belonging to the subphylum Chelicerata and the family Barychelidae. Before the 1980s, trapdoor spiders were not thought to exist in Hawaii. Upon discovery, the species was originally classified as part of the genus Idioctis. However, upon further research by Tracey Churchill and Robert Raven, they were moved to a new genus due to their differing physical attributes, given the name Nihoa, because it was thought to exist nowhere else.{{Cite web |title=ADW: Nihoa mahina: CLASSIFICATION |url=https://animaldiversity.org/accounts/Nihoa_mahina/classification/ |access-date=2025-04-19 |website=animaldiversity.org}}{{Cite journal |last=Yu |first=Kuang-Ping |last2=Lo |first2=Ying-Yuan |last3=Cheng |first3=Ren-Chung |last4=Raven |first4=Robert |title=Discovery of a new intertidal trapdoor spider of the genus Idioctis (Araneae: Barychelidae), with a generic range extension to Taiwan |url=https://www.researchgate.net/publication/374587984_Discovery_of_a_new_intertidal_trapdoor_spider_of_the_genus_Idioctis_Araneae_Barychelidae_with_a_generic_range_extension_to_Taiwan |journal=Journal of Arachnology |volume=51 |pages=238-239}} Eventually, over 23 species across the Pacific were found throughout the southwestern Pacific.{{Cite web |date=2016-08-30 |title=Papah?naumoku?kea: At Home in Our Archipelago |url=https://www.hawaiipublicradio.org/arts-culture/2016-08-30/papah-naumoku-kea-at-home-in-our-archipelago |access-date=2025-04-19 |website=Hawai'i Public Radio |language=en}} The species' conservation status has also been accepted by the science community as a vulnerable species.{{Cite web |title=NMBE - World Spider Catalog |url=https://wsc.nmbe.ch/species/5679/Nihoa_mahina |access-date=2025-04-19 |website=wsc.nmbe.ch}}
Description and anatomy
The spider itself is a species of intertidal trapdoor spider. The species was discovered in moonlight but also has fine silver hair. Its furrow promargin has eight thick teeth and three smaller teeth which act as a multi-purpose tool for spiders within the Chelicerata subphylum. These spiders are hunters that dig a hole near rocks and cover it with a concealed trapdoor. These burrows are excavated completely with the spider's jaw. When prey approaches or falls in, the spider pounces on it. Then its abnormally large pedipalps are used to take food into the mouth.{{Cite web |title=Papahānaumokuākea Hidden Picture |url=https://nmspapahanaumokuakea.blob.core.windows.net/papahanaumokuakea-prod/media/archive/education/kids/pdf/pmnm_hidden_picture.pdf}} Nihoan trapdoor spiders can be distinguished by their wider sternum, the medially located teeth paired claws of the males, and the absence of a second row of teeth on the claws of the females. Male Nihoan trapdoor spiders grow to almost {{cvt|15|mm|in}} long, including their chelicerae. The females are larger, reaching up to {{cvt|21|mm|in}}.{{Cite book |last=Hamlyn-Harris |first=Ronald |url=https://www.biodiversitylibrary.org/page/40007322#page/2/mode/1up |title=Memoirs of the Queensland Museum |last2=Hamlyn-Harris |first2=Ronald |last3=Museum |first3=Queensland |last4=Hamlyn-Harris |first4=Ronald |last5=Museum |first5=Queensland |date=1994 |publisher=Queensland Museum |volume=v.35:pt.2 (1994) |location=Brisbane}} Females also carry a dissimilarity to their vulva which is crucial to the identification of the species.
Distribution and habitat
This species is endemic to the island of Nihoa, Hawaii.{{Cite report |last=Montanio |first=Patricia A. |date=2011 |title=Final damage assessment and restoration plan and environmental assessment for the July 2, 2005, M/V Casitas grounding at Pearl and Hermes Atoll, Northwest Hawaiian Islands, Hawaiian Islands National Wildlife Refuge, Papahānaumokuākea Marine National Monument |publisher=United States Department of Commerce National Oceanic and Atmospheric Administration |url=https://repository.library.noaa.gov/view/noaa/690 |language=en}} They inhabit the area of the coastline that is exposed during low tide and submerged during high tide, and are commonly found by mangrove roots or near loose coral rubble.