Earthworm (Oligochaeta) diversity of Kumaun Himalaya with a new record of Drawida japonica (Michaelsen, 1892) (Monaligastridae) from Nainital, Uttarakhand, India

: The present study was conducted to investigate earthworm diversity in the Kumaun region of Uttarakhand, India. Earthworm sampling was made from 1,409–2,224 m from the foothills of the Kumaun Himalaya to higher altitudes monthly from April 2019 to April 2021, covering the major monsoon season in India. Earthworms were collected from twelve different sites using the hand sorting method and preserved in 10% formalin. We recorded 14 earthworm species representing four families: Megascolecidae ( Amynthas corticis , Amynthas morrisi , Amynthas alexandri , Metaphire anomala , Metaphire houlleti , Metaphire birmanica , & Perionyx excavatus ); Lumbricidae ( Aporrectodea caliginosa trapezoides , Aporrectodea rosea rosea , Eisenia fetida , Octolasion tyrtaeum , & Dendrodrilus rubidus ); Moniligastridae ( Drawida japonica ); and Octochaetidae ( Eutyphoeus nainianus ). Drawida japonica from the family Moniligastridae is being reported for the first time from the Kumaun Himalaya. Moniligastrids are an important, yet often ignored, earthworm group commonly found in cultivated soils of higher altitudes.


INTRODUCTION
Earthworms act on soil structure and function via feeding, digging and excretion, thereby affecting farmland soil nutrients and microbial diversity, and many taxonomists have been drawn towards them McTavish et al. (2021).Indeed, Charles Darwin described earthworms as the most important animal group in the history of the world; Darwin (1881).The first record of earthworm fauna of the western Himalaya was given by Bourne (1889), who described Typhoeus masoni (syn.Eutyphoeus orientalis) from Dehradun (Uttarakhand, India).There are 3,000-7,000 known species of earthworms worldwide (Phillips et al. 2021) but at the same time Misiragloglu et al. (2023) stated that a total of ca.5,738 species/subspecies (5,406 species and 332 unique subspecies; i.e., not counting the nominotypical subspecies) belonging to 23 families (including one non-crassiclitellate family: Moniligastridae) are currently recognized worldwide, of which three families (Tritogeniidae and Kazimierzidae from southern Africa and Arecoidae, a new family from Brazil described herein), 35 genera and close to 1,200 new taxa (including subspecies) were described in the 21 st century.Nonetheless, the large number of undescribed species will likely increase this value to well over 8,000 species, broadly divided into three ecological groups based on feeding and burrowing habits: litter-dwelling epigeic species, shallow-burrowing endogeic species, and deepburrowing anecic species (Lee 1985;Shipitalo & Korucu 2002).In his 1972 seminal book 'Lombriciens de France', Marcel Bouché initially described seven earthworm ecological categories (anecic, endogeic, epigeic, epianecic, endo-anecic, epi-endogeic, and intermediate) (Bouché 1972).
Five years later, he simplified the explanation of these categories by describing a ternary plot in which the three major categories (anecic, endogeic and epigeic) represent the three poles (Bouché 1977).Drawida japonica Michaelsen, 1892 (Oligochaeta, Moniligastridae) is considered an epigeic species because its preferred habitat is mostly humid litter layers or topsoil ground in particular areas like forests, drainage ditches and ponds or reservoirs.Nevertheless, Gates (1972) thought that this species came originally from the Indian Himalayas and questioned the identification of some earlier records from outside Japan or Korea.In India, 89% of the fauna are native and the rest exotic (Julka & Paliwal 2005;Verma et al. 2010).
Kumaun Himalaya, a west-central section of the Himalaya in northern India, ranges from 28° 44' & 31° 28' N and 77° 35' & 81° 01' East.Information on the earthworm community of the Kumaun region is minimal.Earthworms are required to survive a good supply of food, plenty of moisture, enough dissolved oxygen, shelter from sunlight, a balanced pH level, an environment free from toxic substances, and a suitable temperature (Reynolds et al. 2021).The present study is based on the diversity of earthworms located at different altitudes of the Kumaun Himalaya (1,409-2,224 m).The study reported one lumbricid species, Drawida japonica Michaelsen 1892 for the first time from Kumaun Himalaya (Image 1).

MATERIALS & METHODS
Earthworms were collected from Dhari tehsil (29.3397 0 N, 79.5877 0 E), Nainital District of Kumaun Himalaya region, by the hand sorting method from two cultivated land and orchards with two soil depths of 0-10 and 10-20 cm.The earthworms were sampled from twelve different sites for two years (April 2019-April 2021), covering the major monsoon period in India.The sampled worms were washed, anesthetized in 70% ethanol, preserved in 10% formalin and brought to the laboratory for further investigations.

RESULTS
The collected earthworms were identified to species level by the Zoological Survey of India (ZSI), Kolkata and a total of 14 earthworm species belonging to four different families: Megascolecidae, Lumbricidae, Moniligastridae, and Octochaetidae were recorded, with a new record of Drawida japonica from the cultivated land and orchards

DISCUSSION
Fourteen species recorded from the study area, seven were identified belonging to the family Megascolecidae, five from Lumbricidae, one from Moniligastridae, and one from Octochaetidae, respectively.Megascolecidae was dominant in all habitats of the Kumaun Himalaya, and the most widely distributed species was Octolasion tyrtaeum and Eisenia fetida.Drawida japonica belongs to family Moniligastridae has been reported for the first time from the Kumaun region, and for a second time from Uttarakhand.All the other species were reported previously by various authors including: Mubeen & Hatti (2018); Rajwar et al. (Rajwar et al. 2018(Rajwar et al. , 2022)); Bora et al. (2021a,b); Saikia et al. (2021); Ahmad et al. (2022); Khan (2022).Drawida japonica was reported from high-altitude cultivated land and orchards, i.e., 1400 m; therefore, it is assumed that it could be present in other parts of the Himalayan mountains with similar geoclimatic conditions and it is possible that this species might also be available in other parts of the Himalaya besides the studied region due to similarity in biomes.