Diversity and Abundance of Delineated Earthworm (Annelida: Clitellata) in Pakistan: A Review

taxono-Abstract: Earthworm, a ubiquitous (but neglected) macro-invertebrate, is found in terrestrial vicinity of Pakistan. Moreover, the occurrence of earthworms is often diverse with fluctuating quantity depending upon abiotic factors and land usage patterns. The aim of this study was to summarize all the reported information related to earthworm diversity in different areas of Pakistan. Almost all the data published from year 2001 to 2021 were collected. Following data organization, total 42 earthworm’s species including five families (Acanthodrilidae, Lumbricidae, Moniligastridae, Octochaetidae and Megascolecidae) were reported from various researchers. Among five families, family Acanthodrilidae was found to have only one specie ( Ramiella bishambari ), Lumbricidae consist of 10 species ( Apporactodea rosea , Allolobophora trapezoids , Allolobophora chloroticaa , Aporrectodea longa , A. caliginosa , Bimastus parvus , Eisenia fetida , Helodrilus foetidus , Lumbricus terrestris and L. rubillus ), Moniligastridae has two species ( Drawida nepalensis and D. pellucida ) while Octochaetidae possess only one specie ( Eutyphoeus incommodus ). The most abundant and diverse family Megascolecidae consist of 28 earthworm species in all habitats of different regions of Pakistan. Among geographical areas, Faisalabad was found as the richest territory with most reported earthworm species ( i.e. 28). The current study suggests further in depth research to explore the unidentified and/ missing species of earthworms in Pakistan.

lowed by autumn full of rainy seasons 2 . The climate and draining system rivers and canals of Pakistan has great impact on soil fertility and support above 80 of the total biomass of earthworms from soil fauna and flora 3 . Among soil fauna, earthworms are bountiful macro-invertebrates in terrestrial environment 4,5 . Generally, these soil worms dialectically called as soil or ecosystem engineers, are vital for soil fertility and quality 6 . Earthworms, known as nightcrawlers, are belong to phylum Annelida, class Clitellata with 16 families. They are world wide distributed invertebrates and comprise of over 5,500 known earthworm s species 7 , while among these, 590 species of earthworm diversified in south Asia, including Pakistan 8 . However, first official record of earthworm s fauna from south Asia was determined by Templeton in 1844 9 . Later, various species were remarkably identified and added by different taxono-mists in the Asian subcontinent 9,10 . Similarly, in 1916, earthworms of Lahore before partition were previously described by Parshad 11 . After Partition, Bhatti a taxonomist was the first researcher, who identified and confirmed the various earthworm species in different areas of Lahore 12 . Subsequently, a number of researchers also examined and confirmed the existence of earthworms in different region of the Pakistan 13 15 . Now recently, earthworm identification through DNA barcoding technique by utilizing COI gene sequence was also reported for the first time for Sialkot locality, Pakistan 5 .
Pakistan is richest in soil macrofauna like earthworms which increase soil fertility. Although, earthworm species are attentively studied all around the world, they are feebly neglected living organism in Pakistan. Our study is an attempt to summarize the short available online data. The aims and objectives are to sum up the maximum available online reported data on earthworm diversity in different regions of Pakistan.

Material and Methods
Online published articles of earthworm, a native community of soil macrofauna, studies from 2001 to 2021 were downloaded and sorted with respect to our objectives by employing search engine PubMed and Google Scholar. All the selected articles were read and relevant data was sorted. The online surveyed data was organized in tabulate and statistically analyzed via software origin pro 9.0 2022 to construct graph and chart 16 .

Earthworm diversity in Pakistan
The earthworm species abundance and diversity at a specified area is affected by the soil qualities i.e. organic contents, climate and water level , history of land utilization for crop cultivation 17 and seasonal variations 18 . Moreover, certain abiotic physicochemical factors like temperature, pH, nitrogen concentration, availability of phosphorous and potassium, also have great impact on diversity of earthworms 19 . From analysis of cited data, there are 42 reported earthworms, and these worms belong to five families including Acanthodrilidae, Lumbricidae, Megascolecidae, Moniligastridae and Octochaetidae. Among these families, member of Megascolecidae are most abundant i.e. 28/42 , followed by Lumbricidae i.e. 10/42 . While, the families Acanthodrilidae and Octochaetidae consist of only 1 out of 42 reported members. This interpretation exposed that members of family Megascolecidae possess high rank among all the available earthworm families in Pakistan Fig. 2

Habitats of earthworms
Earthworm community dynamics relationship with different habitats and soil forms was well documented all over the world 17 except for Pakistan. Analysis of collected data from relevant research articles represented that 26 earthworm species were found in different habitats such as crop fields, orchids and near water reservoirs of Faisalabad territory. Following Faisalabad, Gujranwala and Lahore were observed to have 17 and 9 earthworm diversity, respectively while 12 diversity was found in both Sialkot and Poonch Fig. 3 . These variations in species richness may be due to increase level of soil fauna or highest re-   Table 1 The reported data of all earthworm species with their names, habitats, areas and sources. search interest in that area. Although, most regions of Pakistan have not mentioned in this study due to absence of study proof or lack of published data. Previously, active association between few earthworm species P. posthuma, P. morrisi and P. hawayana and agroecosystem was studied in Sargodha and Faisalabad 13 . They have also reported the significant association of these species with various habitats like water channels, grass lands, crop land, agricultural practices and orchards. Meanwhile, some researchers determined the significant relationship between earthworm biodiversity, moisture level and variety of vegetations 19,22 . Similarly, the burrowing behaviour and relative richness in various regions such as forest, grass land, agricultural land and river banks were studied 18 . They identified 8 Moniligastridae, 12.05 Lumbricidae and most abundant 73.3

Conclusion
To date, 42 Published data from year 2001 to 2021 earthworm species have been delineated from various habitats of different regions of Pakistan. Among the five explored families namely Megascolecidae 28 , Lumbricidae 10 , Moniligastridae 02 , Acanthodrilidae 01 and Octochaetidae 01 , Megascolecidae is highly diverse with 28 species, from which Pheretima is the largest genera with 20 species in all the study areas. While studying territory, analysis of published data represented that 26 earthworm species were marked in the various habitats like agricultural fields, garden soil, orchids, grass lands and near water bodies of Faisalabad. Meanwhile, Lahore and Gujranwala were considered to have 9 and 17 earthworm species diversity, respectively, while 12 species were found in both Poonch and Sialkot. This study highlights the need of more work on earthworms to explore the species diversity in non-study area of Pakistan.

Author's Contribution
IL designed study. MH analyzed data; or wrote the manuscript. SA, NA, MU, BNK, U and MFQ contributed to information in the submitted manuscript. All authors read and approved the final form of manuscript.