Diversity and distribution pattern of geometrid moths (Insecta: Lepidoptera: Geometridae) along the altitudinal gradient, Kumaun Himalaya, India

Altitudinal gradients are frequently used to study Lepidoptera diversity. The study site, situated in the Munsiari Subdivision of Pithoragarh District, Kumaun Himalaya, was divided into transects along the altitudinal gradient, each 200 m wide, spanning elevations from 1,200–4,000 m. In each transect, a minimum of five sampling plots were established. Furthermore, the study area was divided into five broad zones based on vegetational cover. Moths were collected using automated light traps between 1900 h and 2300 h. The specimens were identified using the available literature and following standard protocols. Indicator species analysis was carried out as per Dufrêne & Legendre. The present paper deals exclusively with the status and altitudinal distribution pattern of the Geometridae moths. Zone II, lying between 1,800–2,600 m, harboured highest species richness (98 species), as well as abundance (4,686 individuals), while the least species richness was encountered in Zone III. In terms of species diversity across the subfamilies, Ennominae comprised 93 species, followed by Larentiinae (49), Geometrinae (14), Sterrhinae (4), and Desmobathrinae (1). In terms of distribution, 23 species, restricted to just one transect and exhibiting distribution for one month, could be categorised as highly specialized, while two species—Euphyia subangulata and Eustroma melancholicum venipicta (Larentiinae)—exhibiting distribution throughout the altitudinal gradient, along with an additional 23 species (all Ennominae) exhibiting presence across five or more transects, could be defined as generalists. Both categories are considered ‘indicator species.’