Species inquirenda

Definition

A species of doubtful identity that requires further investigation to determine its taxonomic status, validity, or relationship to other species. The designation flags taxa whose original descriptions are insufficient, whose type material is lost or inadequate, or whose boundaries with similar species remain unresolved. Unlike nomina dubia, which are names of uncertain application, species inquirenda specifically denotes taxa whose biological reality is questioned rather than merely their nomenclatural availability. The term serves as a provisional status pending revision, often prompting targeted collecting, morphological reanalysis, or molecular study.

Etymology

Latin, literally 'species to be investigated' (feminine plural of inquirendus, gerundive of inquirere, to inquire)

Example

The harvestman Leiobunum nigropalpi was long treated as a species inquirenda in European arachnology because early descriptions lacked diagnostic figures of the male pedipalps; subsequent examination of fresh material from the type locality in Slovenia resolved its identity and confirmed it as distinct from the widespread L. rotundum.

Synonyms

• taxon inquirendum

Related Terms

• Nomen dubium
• species incertae sedis
• nomen inquirendum
• conspecificity
• type fixation
• syntype
• neotype

Usage Notes

The plural form species inquirendae follows Latin grammar but is rarely used in practice; most literature employs the singular for both collective and individual reference. The term implies active uncertainty demanding resolution, distinguishing it from the more passive designation species incertae sedis (of uncertain placement). In modern practice, species inquirenda status often triggers targeted fieldwork to secure fresh material for DNA barcoding or micro-CT imaging. The designation should not be applied to names that are demonstrably invalid (nomina nuda) or permanently unidentifiable (nomina dubia in the strict sense). Some authors restrict species inquirenda to cases where the species itself is questionable, reserving nomen inquirendum for doubtful generic or higher-rank names.