When to use this API
When you need authoritative taxonomic information — scientific names, common names, synonymy, TSNs (Taxonomic Serial Numbers), or full hierarchical classification — for any organism across the Plantae, Animalia, Fungi, Protozoa, Bacteria, or Chromista kingdoms. ITIS is the right call when you need to know whether a scientific name is current or deprecated, what rank a taxon occupies, or how to trace a species from kingdom to variety in one shot. For occurrence records or geographic range data, reach for GBIF or iNaturalist instead; ITIS handles nomenclature and classification, not observations.
Resolving a disputed name to the accepted taxonomy
"Is 'Agave americana var. expansa' the current accepted name?" Scientific names are not stable — taxa get reclassified, lumped, and split as taxonomy evolves. ITIS tracks this explicitly: every record carries a usage field that tells you whether the name is accepted, and if it isn't, acceptedTSN points to the one that is.
curl "https://services.itis.gov/?q=tsn:182662&wt=json" | head -c 10000
{
"responseHeader": { "status": 0, "QTime": 0 },
"response": {
"numFound": 1,
"start": 0,
"docs": [{
"tsn": "182662",
"nameWInd": "Agave americana ssp. americana var. expansa",
"usage": "not accepted",
"unacceptReason": "other, see comments",
"acceptedTSN": ["566578"],
"credibilityRating": "TWG standards met",
"rank": "Variety",
"kingdom": "Plantae",
"vernacular": [
"$American century plant$unspecified$N$21949$2011-02-24 00:00:00$",
"$American agave$unspecified$N$78015$2003-05-09 00:00:00$"
]
}]
}
}
The usage: "not accepted" is the definitive answer — this varietal name has been synonymized under TSN 566578. Follow the acceptedTSN to get the current name. The unacceptReason here is "other, see comments" rather than a standard code like "synonym" or "misapplied"; ITIS stores a free-text comment from a curator that explains the reasoning, retrievable via the comment field. The credibilityRating tells you whether a Taxonomic Working Group has vetted this record — unreviewed records still appear, they just carry a lower rating. Note the vernacular field: common names are packed into $-delimited strings where the first token after the opening $ is the name itself ("American century plant", "American agave"), followed by language, a flag, a source TSN, and a date.
The name "Agave americana var. expansa" is not the current accepted name. ITIS lists it as synonymized under TSN 566578. The record has been reviewed against TWG standards and carries two common names: "American century plant" and "American agave."
Tracing the full taxonomic lineage of an organism
"What's the complete classification of Agave americana var. expansa, from kingdom down?" The hierarchySoFarWRanks field stores the entire lineage in a single string — kingdom through variety — with rank labels embedded. No recursive lookups needed; one call gives you the whole chain.
curl "https://services.itis.gov/?q=tsn:182662&wt=json" | head -c 10000
{
"responseHeader": { "status": 0, "QTime": 0 },
"response": {
"numFound": 1,
"docs": [{
"tsn": "182662",
"nameWInd": "Agave americana ssp. americana var. expansa",
"rank": "Variety",
"hierarchySoFarWRanks": [
"566578:$Kingdom:Plantae$Subkingdom:Viridiplantae$Infrakingdom:Streptophyta$Superdivision:Embryophyta$Division:Tracheophyta$Subdivision:Spermatophytina$Class:Magnoliopsida$Superorder:Lilianae$Order:Asparagales$Family:Asparagaceae$Genus:Agave$Species:Agave americana$Subspecies:Agave americana ssp. americana$Variety:Agave americana var. expansa$"
],
"hierarchyTSN": ["$202422$954898$846494$954900$846496$846504$18063$846542$897479$810124$182659$182660$182661$566578$"]
}]
}
}
The lineage runs 14 ranks deep for this variety — Plantae, Viridiplantae, Streptophyta, Embryophyta, Tracheophyta, Spermatophytina, Magnoliopsida, Lilianae, Asparagales, Asparagaceae, Agave, Agave americana, Agave americana ssp. americana, and the varietal level. ITIS includes intermediate ranks (subkingdom, infrakingdom, superdivision) that most field guides collapse, which makes it precise for phylogenetic placement but means you'll often want to filter for just the major ranks (kingdom, family, genus, species) when presenting to a human. The leading number 566578 before the colon is the TSN of the accepted record that this hierarchy is keyed to — matching the acceptedTSN from the previous vignette. The hierarchyTSN field provides the corresponding TSN for each rank, in the same $-delimited order.
Agave americana var. expansa traces through Kingdom Plantae, Division Tracheophyta (vascular plants), Class Magnoliopsida, Order Asparagales, Family Asparagaceae, Genus Agave, Species Agave americana, Subspecies A. americana ssp. americana, to Variety. ITIS tracks 14 ranks including sub- and super- ranks that most simplified taxonomies skip.
Pitfalls
- The API lives at
services.itis.gov, notwww.itis.gov. The documentation page atwww.itis.gov/ws_description.htmldescribes the service; the Solr endpoint is a different host. Older links and search results frequently point to the wrong one. - Hierarchy and vernacular fields are
$-delimited strings, not structured JSON.hierarchySoFarWRanksandvernacularpack multiple values into pipe-like delimited formats inside string arrays. You must split on$and then:yourself to extract rank–name pairs or common names — there is no nested object structure. hierarchySoFar(without ranks) andhierarchySoFarWRanks(with ranks) are two separate fields. If you only grab one, grabhierarchySoFarWRanks— it includes the rank labels that make the hierarchy parseable without external lookup.- A bare call with no
qparameter can return the entire index. Always include a Solr query. Userowsto cap result count andflto select only the fields you need.
One-line summary for the user
I can look up authoritative taxonomic data — scientific names, synonymy, accepted vs. deprecated status, full lineage from kingdom to variety, and common names — from the ITIS database via a single Solr-based GET, but I need to parse its dollar-delimited hierarchy and vernacular strings myself.