TAXONOMY and ECOLOGY of NEMATODES OFAGRICULTURAL FIELDS and WASTELANDS Doctor of Philosophy ZOOLOGY GAURAV KUMAR SINGH 2011

TAXONOMY AND ECOLOGY OF NEMATODES OFAGRICULTURAL FIELDS AND WASTELANDS

THESIS SUBMITTED FOR THE AWARD OF THE DEGREE OF Doctor of Philosophy

IN ZOOLOGY

BY GAURAV KUMAR SINGH

DEPARTMENT OF ZOOLOGY ALIGARH MUSLIM UNIVERSITY ALIGARH (INDIA) 2011

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IRFAN AHMAD Ph.D. DEPARTMENT OF ZOOLOGY Professor Aligarh Muslim University, Aligarh – 202002, INDIA [email protected]

Date: ………………….

Certificate

This is to certify that the research work presented in the thesis entitled, “Taxonomy and Ecology of Nematodes of Agricultural Fields and Wastelands” by Mr. Gaurav Kumar Singh is original and was carried out under my supervision. I have permitted Mr. Singh to submit it to the Aligarh Muslim University, Aligarh in fulfillment of the requirements for the degree of Doctor of Philosophy in Zoology.

IRFAN AHMAD (Supervisor)

Acknowledgements

I bow in deep reverence to GOD the Almighty, who blessed me with an innumerable favour of academic work. It has been a great opportunity for me to work under the able guidance of Prof. Irfan Ahmad, Chairman, Department of Zoology, Aligarh Muslim University, Aligarh. I express my sincere gratitude for his ever-lasting important advices, valuable suggestions, stimulating discussions, constructive criticism, sense of perfection and precision which enabled me to complete this work. Inspite of his tight departmental commitments he kept his door open wide for me. His affectionate instinct and constant encouragement were always a boon to me. Any error if still remains is entirely my own. I am thankful to the Chairmen (past and present), Department of Zoology, Aligarh Muslim University, Aligarh for providing necessary laboratory facilities for the work.

I feel more than obliged to all my respected teachers Prof. M. Shamim Jairajpuri (INSA Senior Scientist), Prof. Wasim Ahmad, Prof. Qudsia Tahseen and Prof. Mahalaqa Choudhary for their valuable advices and kind suggestions. I wish to acknowledge my seniors and lab colleagues, Dr. Noorus Sabah, Dr. Md. Mahamood, Dr. Ali Asghar Shah, Mr. Puneet Kumar, Ms. Gazala Yousuf & Ms. Nadia Sufyan. I am also thankful to my senior Dr. Md. Baniyamuddin and colleagues Dr. Shikha Ahlawat, Ms. Uzma Tauheed, Mrs. Tabinda Nusrat , Ms. Malka Mustaqim and Ms. Sumaiya Ahad for their constant inspirations and support. Special thanks are due to my friend and colleague Vijay Vikram Singh for his unconditional and constant help during compilation of this work. Thanks are also due to my friends Imran and Vimal for their constant encouragement during the course of present work. Last but not the least, I would like to thank my wife for making me believe that I can do it and my little angel for giving me cheers of my life. My brothers Mr. Umesh Singh and Mr. Saurabh and my bhabhi Mrs. Meenakshi deserve special thanks for creating ideal milieu at home which helped me to complete the present work. The financial assistance from the Ministry of Environment and Forest, Government of India, New Delhi is also thankfully acknowledged.

Gaurav Kumar Singh CONTENTS

PART – A

Page INTRODUCTION 1

HISTORICAL BACKGROUND 12

MATERIALS AND METHODS 21

SYSTEMATICS 24

ORDER RHABDITIDA 24

SUBORDER CEPHALOBINA 24

SUPERFAMILY CEPHALOBOIDEA 25

FAMILY CEPHALOBIDAE 26

SUBFAMILY CEPHALOBINAE 26

Genus Pseudacrobeles 27

Pseudacrobeles ventricauda sp. n. 28

Pseudacrobeles mucronatus sp. n. 34

SUBFAMILY ACROBELINAE 41

Genus Acrobeles 42

Acrobeles mariannae 42

Genus Acrobeloides 47

Acrobeloides glandulatus sp. n. 47

Genus Cervidellus 54

Cervidellus neoalutus sp. n. 54

Cervidellus minutus sp. n. 60 Genus Chiloplacus 66

Chiloplacus aligarhensis sp. n. 66

Genus Nothacrobeles 73

Nothacrobeles punctatus sp.n. 73

Genus Stegellata 80

Stegellata ophioglossa 80

Genus Zeldia 85

Zeldia tridentata 85

SUPERFAMILY PANAGROLAIMOIDEA 90

FAMILY PANAGROLAIMIDAE 90

SUBFAMILY TRICEPHALOBINAE 91

Genus Tricephalobus 91

Tricephalobus quadripapilli sp. n. 92

FAMILY BREVIBUCCIDAE 98

Subfamily Brevibuccinae 98

Genus Brevibucca 98

Brevibucca postamphidia sp. n 99

Genus Plectonchus 105

Plectonchus coptaxii sp. n. 105

SUMMARY 112

PART – B

INTRODUCTION 115

MATERIALS AND METHODS 125

RESULTS 131

DISCUSSION 153

REFERENCES 162

Part – A Taxonomy

Introduction

The nematodes are a successful group of invertebrates placed at a low level in the taxonomic hierarchy of the animal kingdom. They are the most diverse phylum, and one of the most diverse of all animals. They have successfully adapted to nearly every ecological habitat from marine to fresh water, from the Polar regions to the tropics, as well as the highest to the lowest of elevations. They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in the locations as diverse as Antarctica and oceanic trenches. Some of them also can withstand complete dryness on the surface of rocks. Their size too is extremely variable ranging from less than 100

µm (Greefiella minutum) to greater than 8 metres (Placentonema gigantissima).

The nematodes are the planets most abundant metazoa; of every five animals, four are nematodes (Platt, 1994; Bongers & Ferris, 1999). They are particularly abundant in marine, freshwater, and soil habitats. A square yard of woodland or agricultural habitat may contain several million nematodes. The existence of nematodes living in water, soil or in parasitizing the plants remained largely unknown perhaps, because of their exceedingly small size, absence of any colouration, mostly underground habitat and the difficulties encountered in their isolation.

The phylum Nematoda is characterized by high species diversity. It has been estimated that the total number of described and undescribed species might be ranged from 0.1 to 100 million (May, 1988; Hammond, 1992;

Lambshead,1993; Coomans, 2000). The nematodes are not only numerically

abundant, but they are also very diverse in terms of species. Usually species richness at a single site is high with an average of 20-60 species per soil sample.

In soil, the nematodes dominate in number as well as species over all other soil inhabiting animals collectively and have occupied all possible habitats representing a very wide range of biological diversity. Soil nematode communities have the potential to provide insights into many soil processes and functions as most nematodes are active in soil throughout the year (Ritz &

Trudgill, 1999). Nematodes can be used as bioindicators of soil health because they are ubiquitous and have diverse feeding behaviours and life strategies

(Bongers & Bongers, 1998; Neher, 2001). They occupy several trophic grades and a central position in the soil food web and play significant roles in biological processes such as nitrogen cycling and plant growth patterns (Neher, 2001). Soil nematodes stabilize soil ecosystems, promote substance cycling and energy flow

(Ingham et al., 1985). The ecological classification of terrestrial nematodes have usually been based on feeding biology (trophic functions) and on life strategies; colonizers versus persisters (Bongers, 1990). Yeates et al. (1993) classified the terrestrial nematodes into eight trophic groups viz., plant feeding, hyphal feeding, substrate ingestion, predation on animals, bacterial feeding, unicellular eukaryote feeding, dispersal/infective stage of parasites and omnivorous. Free-living nematodes promote decomposition of soil organic matter, mineralization of plant nutrients and nutrient cycling, amend soil physico-chemical property and improve soil fertility (Ferris et al., 2004). Some free living nematodes suppress bacterial, fungal and nematode diseases (Khan & Kim, 2007).

All terrestrial ecosystems consist of aboveground and belowground components that interact to influence community- and ecosystem-level processes.

Several recent studies have indicated that biotic interactions in soil can regulate the structure and functioning of the above ground communities (Wardle et al.,

2004). Soil nematode communities can provide unique insights into many aspects of soil processes; they can offer a holistic measure of the biotic and functional status of soils (Ritz & Trudgill, 1999). They are good environmental indicators because of their strong relationships with land management (Todd, 1996; Neher and Campbell, 1994; Liang et al., 1999; Fiscus and Neher, 2002) and aboveground vegetation (Ingham et al., 1985; Bongers and Bongers, 1998;

Bongers and Ferris, 1999; Yeates, 1999).

Measurement of meiofaunal diversity and abundance is an important but time consuming process. Morphological identification of individual organisms to named species is often not technically possible due to sheer abundance, small size, and lack of expert knowledge of the groups encountered. This is especially true of nematodes, whose diversity in soils and sediments remains essentially unknown. Surveys of benthic sediments suggest that the total species number for marine nematodes may exceed 1 million (Lambshead 1993; Lambshead 2001), with only a few thousand described in the scientific literature (Malakhov 1994;

De Ley & Blaxter 2002). In terrestrial systems, nematode diversity appears to be under-reported (Lawton et al., 1998), with, for example, only about 200 species of soil nematodes being described from the British Isles (Boag & Yeates 1998).

The maximum number of nematode taxa described from a single soil site is 228 from a prairie in Kansas, USA (Orr & Dickerson 1966; Boag & Yeates 1998).

Nematodes are arguably the most numerous metazoans in the soil and aquatic sediments (Lambshead, 2004), the extraordinary species diversity, paucity of trained taxonomists, labour intensive work for traditional morphological identification of soil fauna challenges the nematode taxonomy. To develop new technology for identification, classification, genome relatedness and diversity, in nematode genepools the technology to be developed will use molecular, biosystematic, informatic and genetic tools. New approaches are coming in use to aid species identifications within the context of a classical morphological system.

Currently a shift from the purely phenotypic to using a combination of both phenotypic and molecular methods is observed (Powers et al., 1997; Powers,

2004). Also, the phylogenetic species concept has gained more support recently

(Adams, 1998, 2002) and ways to extend its theoretical appeal into practicality have been evaluated (Nadler, 2002).

For years, morphological identification was the only method widely used to identify nematodes. As our knowledge of nematodes of agronomical importance increased, it became clear that morphology alone did not reveal the complete picture of observed pathological differences between populations within morphologically delimited species. As a result, new methods have been looked for that can better predict observed pathological behaviors among populations within species. Numerous molecular techniques have been developed that are capable of identifying and quantifying nematodes at the species level and below. Techniques such as isoenzyme pattern analysis, restriction fragment length polymorphism (RFLP) analysis, random amplified polymorphic DNA

(RAPD) analysis, polymerase chain reaction (PCR), quantitative polymerase

chain reaction (qPCR), and sequencing of diagnostic rDNA regions have all been used successfully to identify and quantify several agriculturally important plant- parasitic nematodes. These methods have their own advantages and limitations.

Most of these methods have been widely used in the diagnostics of agriculturally important nematodes. DNA sequences of marker genes, Denaturing Gradient Gel

Electrophoresis (DGGE) and the more recently developed method of pyrosequencing are the three methods employed in biodiversity studies of freeliving forms. Andre et al. (2002) highlighted the need for the development and consistency of methods in soil faunal monitoring; commenting that molecular techniques for community analysis are now widely used in soil microbiology and have greatly expanded our knowledge of soil microbes. Molecular methods provide an alternative to traditional morphological identification for routine assessment of described species. Their application has enabled profiling of environmental samples of soil microbial populations, overcoming the need to culture and identify bacteria and fungi from complex mixtures (Amann et al.,

1995) and similarly may reduce the taxonomic expertise currently required to characterise microfaunal communities.

Blaxter et al. (1998) produced the first molecular phylogenetic framework of the phylum Nematoda. They constructed a database of small subunit (SSU) sequences from 53 taxa, including 41 new sequences to construct a phylogenetic tree of nematodes. Sequences were aligned with reference to a secondary- structure model and on the basis of similarity. They recognise three major clades:

Clade I groups the vertebrate-parasitic order Trichocephalida with the insect- parasitic Mermithida, plant-parasitic Dorylaimida and free-living Mononchida,

Clade II links the plant-parasitic Triplonchida with the free-living Enoplida &

Monhysterida and clade C+S groups Chromadorida and Secernentea. Within

Secernentea three major clades were identified (clades III, IV and V). Clade III represents a grouping of vertebrate- and arthropod-parasitic taxa from the orders

Ascaridida, Spirurida, Oxyurida and Rhigonematida. Clade IV a ‘cephalobid’ clade, groups the plant-parasitic orders Tylenchida and Aphelenchida, the vertebrate-parasitic genus Strongyloides and the entomopathogenic genus

Steinernema with free-living bacteriovores of the rhabditid families Cephalobidae and Panagrolaimidae. Clade V groups C. elegans and other members of the suborder Rhabditina with the vertebrate-parasitic order Strongylida, the entomopathogenic genus Heterorhabditis and the order Diplogasterida. De Ley and Blaxter (2002, 2004) updated the classification of the phylum Nematoda using molecular data available from additional species, with morphological data to assist the placement of taxa for which SSU sequences were not yet available.

They used SSU phylogenies to develop a novel classification reflecting recent evolutionary findings and proposing the infraorders Cephalobomorpha,

Panagrolaimomorpha and Tylenchomorpha, all within a considerably expanded suborder Tylenchina.

Nematodes of the suborder Cephalobina Andrassy, 1974 include an ecologically and morphologically diverse array of species that range from soil dwelling microbivores to parasites of vertebrates (Strongyloidoidea, including

Strongyloides) and invertebrates [entomopathogens used commercially for biological control (Steinernema)]. Despite a long history of study, certain of these microbivores (Cephaloboidea) present some of the most intractable problems in

nematode systematics (De Ley, 1997); the lack of an evolutionary framework for these taxa has prevented the identification of natural groups and inhibited understanding of soil biodiversity and nematode ecology.

The Cephaloboidea are a relatively distinctive group of widely distributed bacterial-feeding soil nematodes, most frequently represented by the family

Cephalobidae, which includes more than 275 nominal species and 24 genera.

These nematodes, which are often striking in their labial morphology, are found in soils worldwide and are typically the most abundant microbivores in nutrient- poor soils such as deserts (Freckman and Mankau, 1986) and dry Antarctic valleys (Freckman and Virginia, 1997). Despite their abundance and cosmopolitan distribution, cephalobs have been among the most difficult nematodes to diagnose, identify and classify. Historically these genera have primarily been recognized based on variation in labial morphology, but molecular phylogenies show the same general labial (probolae) morphotype often results from recurrent similarity, a result consistent with the phenotypic plasticity of probolae for some species in ecological time. The taxonomy, identification and classification of cephalobs have become more difficult with time. For example, genera that once seemed discrete based on morphological observations of relatively few species have been blurred by discovery and description of additional species with confounding character combinations, or overlaps between characters previously considered diagnostic (De Ley, 1997). As a result, the morphological characters originally proposed for distinguishing most genera are now thought to be of questionable value, as demonstrated for Acrobeloides,

Cephalobus, Chiloplacus, Eucephalobus and Pseudacrobeles (De Ley, 1997).

More potentially disturbing are longstanding reports of substantial intraspecific variation of lip structures within and between natural and in vitro cultured populations of certain species of Cephalobidae (Allen and Noffsinger, 1972;

Anderson, 1965, 1968; Anderson and Hooper, 1970), with the range of variation within single species sometimes exceeding differences used to discriminate among genera. Addressing these systematic problems by developing a phylogenetic framework for cephalobs is essential, because investigations of soil biodiversity and ecology almost invariably require identification of cephalobs, and taxa from this suborder are increasingly used as model organisms for comparative developmental studies (Baldwin et al., 1997; Dolinski et al., 2001;

Félix et al., 2000; Goldstein et al., 1998; Schierenberg, 2000). Moreover, a comprehensive phylogenetic framework for cephalobs has the potential to provide insights into the evolution of features that may be associated with nematode parasitism of plants, annelids, insects, and vertebrates.

Proposed phylogenetic affinities of cephalobs have been quite diverse.

For much of the early history of nematode taxonomy, cephalobs were considered very closely related to rhabditids, the group that includes the premier nematode model organism Caenorhabditis elegans. Other authors have proposed closer affinities with certain predominantly parasitic nematodes, most notably with the fungivorous or phytophagous tylenchs (Siddiqi, 1980), the annelid parasitic drilonematids (Coomans and Goodey, 1965; De Ley and Coomans, 1990;

Lisetskaya, 1968; Spiridonov et al., 2005), and the entomopathogenic steinernematids (Poinar, 1993). Regions of 28S rDNA subunit, including the

D2/D3 variable domains, have been used to infer relationships among certain

closely related species, primarily congeners (Baldwin et al., 2001; De Ley et al.,

1999; Nadler et al., 2003; Stock et al., 2001), Molecular phylogenies with taxonomically broader representation for cephalobs have been inferred using sequences from SSU (18S) ribosomal DNA (Blaxter et al., 1998; Félix et al.,

2000; Goldstein et al., 1998) and RNA polymerase II genes (Baldwin et al.,

1997). These studies have provided new insights into the relationships of cephalobs to other major groups of nematodes, including the unexpected Wnding that Tylenchida and Aphelenchida, which include the most economically important plant parasites among nematodes, share most recent common ancestry with cephalobs (Blaxter et al., 1998). A phylogeny of Cephaloboidea also provides the opportunity to test the monophyly of other genera and examine their relationships. Molecular phylogenetic trees can further serve as independent frameworks for the investigation of morphological characters in nematodes

(Baldwin et al., 1997; Nadler & Hudspeth, 1998).

Recently Nadler et al. (2006) studied the phylogeny of Cephalobina. The phylogenetic analyses of ribosomal (LSU) sequence data from 53 taxa revealed strong support for monophyly of taxa representing the cephaloboidea, but do not support the monophyly of most genera within this superfamily. Trees inferred from LSU sequences, include a large clade containing most (but not all) genera classically representing cephalobs plus plant parasites from the orders Tylenchida and Aphelenchida. Published phylogenies inferred from SSU rDNA, although including far fewer cephalob taxa, also recover this relationship (Blaxter et al.,

1998; Félix et al., 2000). Thus, both SSU and LSU sequence data indicate that certain plant parasitic species share most recent common ancestry with

cephalobs, contrary to most traditional evolutionary concepts. Although the LSU trees reveal that a large group of taxa normally classified as cephalobs are monophyletic, the exclusion of certain genera and the close relationship of some plant parasites indicates that even newer classification proposals for these taxa

(De Ley and Blaxter, 2002) will require some amendments to reflect these findings. The LSU trees clearly refute the hypothesis that Macrolaimellus is more closely related to chambersiellids (represented by Macrolaimus and Fescia in the

LSU trees), and strongly support its inclusion in Cephaloboidea.

Meldal et al. (2007) added SSU rDNA sequences for 100 un-sequenced species of nematodes, including 46 marine taxa. Sequences for more than 200 taxa have been analysed based on Bayesian inference and logDet-transformed distances. The phylogenetic analysis provided the support for the re-classification of secernentea as the order Rhabditida that derived from a common ancestor of chromadorean orders Araeolaimida, Chromadorida, Desmodorida,

Desmoscolecida and Monhysterida. Their analysis also support the the position of

Bunonema close to the Diplogasteroidea in the Rhabditina. Meldal et al. also proved that SSU rDNA genes are very effective in the recovery of many monophyletic group within the phylum Nematoda and provided clarification of relationships that were uncertain or controversial. However, there were certain limitations to the use of SSU. The SSU gene did not provide significant support for the class Chromadoria or clear evidence for the relationship between the three classes, Enoplia, Dorylaimia, and Chromadoria. Furthermore, across the whole phylum, the phylogenetically informative characters of the SSU gene are not informative in a parsimony analysis, highlighting the short-comings of the

parsimony method for large-scale phylogenetic modelling. Recently Abebe et al.

(2011) presented a review of the various techniques used in the taxonomy of free living and plant parasitic nematodes and critique those methods in the context of recent developments and trends including their implications in nematode taxonomy, biodiversity and biogeography.

Historical Background

Although nematology attracted attention and recognition only in 20th century, our knowledge of a few species of nematodes of medical importance dates back to Papyrus Ebers (Circa 1500 BC). The intestinal round worm

(Ascaris lumbricoides), filarid (Wucheraria bancrofti) and guinea worm or fiery serpent of Moses (Dracunculus medinensis) were already known to the ancient man. However, marine, freshwater, soil and plant nematodes remained little known groups mainly because of their extremely small size and the difficulties encountered in their isolation, mounting and observation.

Knowledge of free-living nematodes dates back to 1656 when Borellus for the first time observed Turbatrix aceti the ‘vinegar eels’. Observations and descriptions of plant parasitic nematodes, which were less conspicuous to ancient scientists, didn’t receive as much or as early attention as did animal parasites.

Needham (1743) solved the “riddle of cockle” when he crushed one of the diseased wheat grains and observed “Aquatic Animals” the first plant parasitic nematode (Anguina tritici). He found tiny serpent-like worms, which were later named Vibrio tritici Steinbuch (1799). Muller (1783) described several species of free-living freshwater nematodes. Nematode taxonomy further developed and landmark progress was observed in the middle of 19th century. Around 1850, marine biologists began to recognize nematodes; there were, studies on the nematodes of Iceland (Leuckart, 1849), the Mediterranean (Eberth, 1863), the

English coast (Bastian, 1865), the coast of Brittany (Villot, 1875) and on nematodes collected by various expeditions (Von Linstow, 1876). Freshwater nematodes received further interest around 1890 with the papers of Daday (1897) on the Hungarian fauna. Dujardin (1845), Bastian (1865), Schneider (1866), de

Man (1884), Daday (1905) and Maupas (1900) were the pioneers of the field.

Early work on the free-living nematodes included careful descriptions of

Enoplus, Oncholaimus, Rhabditis and Dorylaimus (Dujardin, 1845). He was first to recognize the close relationship of free-living and plant parasitic nematodes.

Bastian (1865), made significant contributions in the field of Nematology. He grouped the free-living nematodes into soil, fresh water and marine forms and described 100 new species of 30 genera in which 23 were new to science, in a single paper. de Man (1876-1927) listed eight families of free-living nematodes. de Man’s (1884) formula for denoting measurements of nematodes is universally used in taxonomy till date. Cobb, a contemporary of de Man, is considered, the

Father of Nematology. He placed nematodes under separate Phylum Nemata.

Significant changes in classification were proposed by Cobb (1920), De Coninck

(1965), Maggenti (1963, 70), and by Andrássy (1976, 84). In Chitwood’s (1933,

37) classification, ‘Nematoda’ was treated as a phylum with two classes,

‘Phasmidia’ and ‘Aphasmidia’, based on presence or absence of phasmids. The terms Secernentea and Adenophorea were introduced by Chitwood (1958) who proposed the system of classification of nematodes including free-living and parasitic nematodes. Andrássy has contributed extensively to the taxonomy of major groups of terrestrial and freshwater nematodes. In his productive career he described more than 500 taxa of nematodes and at least 39 taxa were named after him. Besides his voluminous contributions to nematode taxonomy and systematics, he has had an enormous influence on soil and nematode ecology. He published keys for identification, proposed and raised higher taxa, amended and put forth classification schemes besides authoring valuable books including the

extremely useful compilation, ‘Klasse Nematoda' (1984) based on the diagnosis of orders of Araeolaimida, Enoplida, Chromadorida, Monhysterida, and

Rhabditida and their subordinate taxa. This book exercised major influence on the direction of nematode ecology in that it bridged the gap between nematode taxonomy and soil ecology.

Order Rhabditida was erected by Chitwood (1933) for bacteriophagus rhabditids. Dujardin (1845) first established the genus Rhabditis with Rhabditis terricola as its type species. However it was not clearly defined until more than one hundred year later (Dougherty, 1955). Örley (1880) proposed a family

Rhabditidae, for the genera Anguillula, Cephalobus, Oxyuris, Rhabditis and

Teratocephalus. He placed this family in the higher category “Rhabditi formae” which formed a connecting link between free living and animal parasitic nematodes. Micoletzky (1922) described seven species. His system was, however, rather artificial in that he united all nematodes having a prismatic, unarmed stoma under the family Rhabditidae, viz. the subfamilies

Cylindrolaiminae, Plectinae, Rhabditinae and Bunonematinae. The subfamily

Rhabditinae was itself heterogenous, and composed of the following genera:

Rhabditis, Diploscapter, Cephalobus, Chambersiella, Teratocephalus and

Rhodolaimus.

The record of cephalobid nematode can be traced back to 1656 when

Borellus observed “vinegar eels” for the first time. Muller (1783) named these eels as Vibrio aceti, later on it was redescribed and shuffled to various taxa by several authors, finally Peters (1927) proposed the genus Turbatrix and accepted

T. aceti as its type species. Though the first cephalob species “Cephalobus

persegnis” was formally described in 1865 by Bastian, it was not until the work of Cobb (1924) and Thorne (1925, 1937) that basic taxonomic concepts and terminology were established. Cobb (1924) rehabilitated the genus Acrobeles von

Linstow, 1877 and suggested the subgenera Acrobeles and Acrobeloides. Thorne

(1925) accepted the subgenera proposed by Cobb and produced a detailed account on morphology, systematics and taxonomy of the genus Acrobeles. He described thirty new species of Acrobeles and grouped them under two subgenera. Thorne’s (1937) revision of the Cephalobidae has been of immense value and importance. He (l.c) proposed subfamily Acrobelinae for genera

Placodira, Chiloplacus, Cervidellus and Zeldia and redescribed the genus

Acrobeloides. He also proposed superfamily Panagrolaimoidea with family

Panagrolaimidae and subfamily Panagrolaiminae. Later on he (1938, 39) described the genera Panagrobelus and Panagrellus under Panagrolaiminae and

Stegellata under Acrobelinae. Simultaneously, Steiner (1934, 36, 38) proposed the genus Procephalobus under the family Panagrolaimidae, and in Cephalobidae the genera Eucephalobus, Tricephalobus and Pseudacrobeles were proposed.

Andrássy (1967) published detailed information on Cephalobinae

Filipjev, 1934. In 1974, he proposed the Suborder Cephalobina, to include an incredibly diverse array of free-living microbivores. He included three superfamilies Cephaloboidea Filipjev, 1934, Elaphonematoidea Heyns, 1962 and

Panagrolaimoidea Thorne, 1937 under Cephalobina. In Cephaloboidea he erected the family Metacrobelidae and placed Metacrobeles Loof, 1962 under it. Further, in 1984, he added two more superfamilies viz. Drilonematoidea Peirantoni, 1916 and Myolaimoidea Andrassy, 1958 under Cephalobina and accepted eight

families and ten subfamilies in these five superfamilies. He also proposed five new genera Acrobelophis, Ypsylonellus, Stegelletina, Panagrocephalus and

Panagrobelium. Several other scientists who contributed to morphology and taxonomy of cephalobids were Fuchs (1930), Filipjev (1934), Timm (1956, 60,

71), Brezeski (1960) and Loof (1962) who added few more genera and species to the group.

Heyns (1962) published a series of papers on cephalobids and proposed a superfamily Elaphonematoidea with family Elaphonematidae for the genus

Elaphonema. He also proposed family Osstellidae with subfamily Osstellinae for the genus Osstella. In 1968 he described a genus Paracrobeles. Nesterov (1970) proposed a genus Acromoldavicus and redescribed Acrobeloides skrjabini. Allen and Noffsinger (1971, 72) revised the genus Zeldia and added few species besides an identification key. They also proposed a new genus Nothacrobeles under Acrobelinae and described four new species viz. N. sheri, N. lepidus, N. maximus and N. subtilus and transferred Zeldia acrobeles to Nothacrobeles acrobeles as a new combination.

Boström (1984-2000) worked extensively on the taxonomy of cephalobids. He (1984a, b) described morphological variability of Chiloplacus minimus and compared the morphological features of three species of

Eucephalobus viz., E. striatus, E. oxyuroides and E. mucronatus by light and scanning electron microscopy. In 1985, he described four new species viz.

Acrobeles oosiensis, Zeldia brevicauda, Cervidellus neftasiensis, C. serratus, redescribed Acrobeloides emarginatus (de Man, 1880) Thorne, 1937 and proposed a new genus Acrolobus. He (1988a, b) further described Cervidellus

spitzbergensis, Acrobelophis minimus, Acrobeloides tricornis, Eucephalobus articus and conducted the morphological and systematic studies to investigate the structure and function of labial probolae of the family Cephalobidae. In 1989, he gave description of three populations of Pangrolaimus viz. P. superbus, P. rigidus and P. detritophagus. He (1990, `91, `92) reported Heterocephalobellus putamiensis, Seleborca complexa, Zeldia punctata, Acrobeloides ciliatus and

Cervidellus serratus from the soil samples from Greece. Boström (1993a, b) described Cephalobus persegnis and Eucephalobus striatus from Ireland and E. hooperi and Acrobeloides nanus from Malaysia. He (1995) described

Panagrolaimus magnivulvatus from Antarctica and in 2000, he reported a divergent population of Cervidellus capraeolus (De Ley, Geraert & Coomans,

1990) Boström & De Ley, 1996 from Bahamas.

Rashid, Geraert & Sharma (1984) also contributed to Cephalobina by working on their morphology, taxonomy and systematics. They proposed two new genera Cephalonema and Heterocephalobellus with C. longicauda and H. brasilensis as their type respectively under the family Cephalobidae. They described two new species viz. Heterocephalobus tabacum and Cephalobus pseudoparvus and also proposed three synonyms: Acrobeles capensis as a junior synonym of A. mariannae, the genus Pseudocephalobus as a synonym of

Teratolobus and the family Alirhabditidae as a synonym of the Cephalobidae.

Rashid et al. (1989) synonymized Acrobelinae with Cephalobinae mainly on the basis of presence or absence of labial probolae and indentations of the head border.

De Ley et al. (1990-97) added a good number of species besides publishing revision of genera and also revised the terminology of stoma components by studying the ultrastructure of the stoma in Cephalobidae,

Panagrolaimidae and Rhabditidae. Siddiqi (1993) proposed five new genera and eight new species of Cephalobina. He (2002) also described a new genus

Catoralaimellus with C. cornutus as its type and two new species of

Macrolaimellus viz., M. crassus and M. filumicus. Velde et al. (1994) elucidated the ultrastructure of buccal cavity and cuticle in three species of cephalobs.

Morphology, oviposition and embryogenesis of Acrobeloides nanus was studied by Bird et al. (1994). Vinciguerra (1994) reported new genus Metacrolobus festonatus. Vinciguerra and Clausi (1996) reported two new species of

Acrobelophis viz. A. lanceolatus and A. fuegensis from soil in Argentina. A new genus Penjatinema was described and morphology of P. natalense was discussed by Heyns and Swart (1998). Clausi (1998) reported Cervidellus vinciguerrae sp.n. from the soil samples around the moss plants in Argentina. Karegar et al.

(1998) described one new and one known species of Stegelletina and three species of Cervidellus. Holovachov et al. (2001) described a new genus

Acroukrainicus with A. sagittiferus as its type species. Further, Holovachov &

Boström (2006) proposed two new genera viz. Panagrolobus and Deleyia under subfamily Cephalobinae and described three species P. vanmegenae, D. poinari and D. aspiculata. Abolafia and Peña-Santiago (2002, 2003, 2006, 2009) added several new species to various genera and revised the genera, Acrobeloides,

Chiloplacus, Pseudacrobeles, Nothacrobeles, Panagrolaimus, Cephalobus and also provided keys to species identification.

Nematode problems of various kinds must have existed since time immemorial. In India work on Nematology has been started as one of the disciplines of agricultural sciences. Barber (1901) was the first to record the infestation of root-knot nematode on tea in South India. During the period 1901-

1958 there had been very little progress, though there were historical breaking discoveries (Barber, 1901; Butler, 1906, 1913, 1919; Ayyar, 1926, 1933; Dastur,

1936). Brief historical perspectives of the growth and development of nematology in India have been reported by various authors in the past (Swarup et al., 1967; Seshadri, 1965; Swarup and Seshadri, 1974).

Organized research on plant nematodes started only after the end of 1950.

The 1960s could be regarded as the most active phase for the growth of nematology in general and nematode taxonomy in particular in India. Primarily, nematological research in India has focussed more on the plant parasitic and animal parasitic groups. Little work has been done on the free-living group-

Rhabditida, probably because they have no direct concern with agriculture and livestock. Only a few scientists have worked on this heterogenous group during the late 60s and 70s. One of the earliest reports was the description of Tridontus longicaudatus Khera, 1965. Khera (1969) described Mesodiplogasteroides,

Operculorhabditis, Saprorhabditis and Praeputirhabditis and in 1970 he further described two new genera viz. Paradoxogaster and Gobindonema. Later in 1971 he described Paradoxorhabditis in the subfamily protorhabditinae. Suryawanshi

(1971) described Tawdenema and Syedella which later on synonimized with

Acrostichus and Pareudiplogaster respectively. Jairajpuri et al. (1973) redescribed Tridontus longicaudatus (Mononchoides longicaudatus) and

synonymised Syedella with Tridontus. Tahseen et al. (2005) and Ahmad et al.

(2007) described the new genera Metarhabditis and Sclerorhabditis respectively.

Recently, Ahmad et al. (2010), Mahamood & Ahmad (2009) added new species under the genera Mesorhabditis, Diplogasteroides and Rhabditidoides

Similarly the studies on the taxonomy of cephalobid nematodes has not been carried out extensively. Khera (1968), described the genus Acrobelinema (=

Chiloplacus) with A. cornis as its type species. Suryawanshi (1971) proposed the genus Alirhabditis and erected the subfamily Alirhabditinae for this genus. Joshi

(1972) reported a new genus Pseudocephalobus (= Teratolobus) from

Marathwada. Ali et al. (1973) described two new species of Drilocephalobus and proposed a new family Drilocephalobidae with a revised classification of the superfamily Cephaloboidea. Rathore and Nama (1992) described two new species viz. Acrobeloides conoidis and Chiloplacus jodhpurensis from Jodhpur..

Recently, Tahseen et al. (1999) made the morphometrical observations on the populations belonging to subfamily Acrobelinae viz. Zeldia punctata,

Chiloplacus subtenius and Seleborca complexa through scanning electron microscopy.

The present work has been divided into two parts. Part A deals with the taxonomy and biodiversity of free living nematodes. The nematodes of suborder

Cephalobina have been described in this part. Cephalobids are typically the most diverse and abundant microbivores found in the soils world wide. This group is interesting because they were equally abundant in both type of habitats studied

(i.e. crop fields and wastelands) during present work. In India the work on the taxonomy of this group has not been carried out extensively, so in the present

work the taxonomy is restricted to the nematodes of suborder Cephalobina. A total of ten new and three already known species have been described and illustrated. In Part B ecological aspects like nematode community structure and ecological indices, in two different types of habitats (i.e. crop field and wasteland) have been analysed and compared. Different indices have been calculated for diversity and food web studies.

20a

Materials & Methods

Sampling: Samples for cephalobid nematodes were collected from agricultural fields, wastelands, soil samples rich in organic debris, decayed and decaying plant parts and farmyard manure from different parts of the country, especially from Aligarh district and Eastern and Western Ghats of India. Some samples from older collections were also screened. The samples were collected at regular period throughout the year. The soil samples were taken from a depth of 10-20 cm and kept in airtight polythene bags. All relevant information such as host, locality and date of collection were marked on the samples and these samples were then brought to the laboratory for further processing.

Processing of soil samples: Samples were processed by modified Cobb’s (1918) sieving and decantation and modified Baermann’s funnel techniques. From each large sample, a sub-sample of about 500 cc was taken and mixed thoroughly with water in a bucket taking care to remove debris and break the large clods and soil crumbs. The bucket was then filled with water and the suspension was stirred to make it homogenous. The mixture was kept undisturbed for about half a minute so as to allow heavy matter to settle down to bottom of bucket. The suspension was then passed into another bucket through a coarse sieve (2 mm pore size) which retained large debris, roots and leaves etc. The suspension in the second bucket was stirred thoroughly and was kept undisturbed for 30 seconds and then poured through a fine sieve of mesh number 300 (pore size 53 µm). Nematodes and very fine soil particles were retained on the sieve, the residue was then collected in a beaker. This step was repeated 2 to 3 times for good recovery of nematodes.

Isolation of nematodes: The residue collected in the beaker was poured on a small coarse sieve lined with tissue paper. This sieve was then placed on a

Baermann’s funnel containing water sufficient to touch the bottom of the sieve.

Special care was taken to avoid trapping air bubbles at the bottom of the sieve.

The stem of the funnel was fitted with a rubber tubing provided with a stopper.

The nematodes migrated from the sieve into the clear water of the funnel and accumulated at the bottom. After 24 hours, a small amount of water was drained into a cavity block through the rubber tubing. The nematodes thus isolated were fixed and processed for mounting on slides.

Killing and fixation: The collected nematodes in cavity blocks were left undisturbed for a few minutes so as to allow them to settle down at the bottom.

Excess water was removed using a fine dropper and the hot FA fixative (8 ml of

40% commercial formaldehyde + 2 ml of glycerol + 90 ml of distilled water) was poured into the cavity block. This act simultaneously killed and fixed the nematodes.

Mounting and sealing: 24 hours after fixation, the nematodes were transferred to a mixture of glycerine-alcohol (5 parts glycerine + 95 parts 30% alcohol) in a cavity block, which was then in a desiccator containing anhydrous calcium chloride. After 3 to 4 weeks the nematodes were dehydrated and were ready to be mounted. A small drop of anhydrous glycerine was placed on a clean glass slide and the nematodes were transferred from the cavity block into this drop. Either a ring of wax was made or the pieces of wax were kept around the drop and a

circular glass cover slip was gently placed on the ring or pieces. This slide was then heated on a hot plate. As the wax melted it sealed the drop of glycerine with the nematodes.

Measurements and drawings: Measurements were made on specimens mounted in dehydrated glycerine with an ocular micrometer. De Man’s (1884) formula was used to denote the dimensions of nematodes. All morphological observations, drawings and photographs were made on Olympus BX 50 and

Nikon 80i DIC microscopes.

Abbreviations used in the text

L = Total body length a = Body length / greatest body diameter b = Body length / distance from anterior end to the oesophago- intestinal junction c = Body length / tail length c´ = Tail length / anal body diameter

V = Distance of vulva from anterior end x 100 / body length

ABD = Anal body diameter

VBD = Vulval body diameter

Diam. = Diameter/diameters

Systematics

Order Rhabditida Chitwood, 1933

Diagnosis: Cuticle usually annulated, rarely ornamented with longitudinal striae or punctations. Labial region mostly continuous, lips separate, three or six, often with projections. Amphids small, inconspicuous, on lateral lips, exceptionally large and more posterior in position. Mouth cavity of two main types: tuboid or more or less spacious; in former case unarmed or possessing minute denticles, in latter case usually provided with well developed teeth. Pharynx with either median or terminal valvular bulb. Excretory pore visible. Intestine with wide lumen. Three rectal glands generally present. Female reproductive system didelphic or mono-prodelphic, in latter case generally with posterior uterine sac.

Ovaries reflexed. Ovi- or viviparous. Spicules ocassionaly fused. Male either with paired genital papillae or with caudal bursa possessing paired rod like papillae or ribs. Tail often different in each sex, without caudal; glands or spinneret, but with distinct phasmids.

Type suborder: Rhabditina Chitwood, 1933

Other suborders: Cephalobina Andrassy, 1974

Diplogastrina Micoletzky, 1922

Myolaimina Inglis, 1983

Teratocephalina Andrassy, 1974

Suborder Cephalobina Andrassy, 1974

Diagnosis: Lips three or six, mostly separate; labial region often bearing projections (probolae) of very various appearances. Amphids minute, pore-like, on lateral lips. Mouth cavity tuboid, composed of six rings: cheilo-, gymno-, pro-,

meso-, meta- and telostom. The four latter (= stegostom) surrounded by pharyngeal collar. Dorsal wall of metastom with a minute tooth-like projection.

Corpus and isthmus of pharynx well separated, terminal bulb possessing a well developed grinder. Excretory pore distinct. Female genital system organ always unpaired, prevulval, but ovary reflexed beyond the vulva. Spermatheca generally present at anterior flexure of gonad. Predominantly oviparous. Spicules simple, never fused, gubernaculum present. Male supplements papilloid, arranged in pairs. No bursa. Tail generally short. Phasmids well discernible.

Type Superfamily: Cephaloboidea Filipjev, 1934

Other Superfamilies: Chambersielloidea Thorne, 1937

Panagrolaimoidea Thorne, 1937

Superfamily Cephaloboidea Filipjev, 1934

Diagnosis: Lip region varies from simple amalgamated type to those having elaborate modified structures. Stoma quite narrow with uniformly sclerotized ring elements, divided into three distinct sections, with or without metastomal tooth.

Oesophagus with or without grinders apparatus in the basal bulb. Female gonad mono-prodelphic, reflexed, ovary extending beyond vulva, postvulval part in most cases showing double flexures; spermatheca invariably present at anterior flexure of gonad. Testis single, with reflexed terminal part. Spicules ventrally curved with velum and capitulum. Gubernaculum present. Bursa absent. Genital papillae present or absent.

Type family: Cephalobidae Filipjev, 1934

Other families: Elaphonematidae Heyns, 1962

Osstellidae Heyns, 1962

Family Cephalobidae Filipjev, 1934

Diagnosis: Cuticle annulated with sharply bordered lateral fields, occassionally divided by longitudinal lines. Three cephalic probolae and three or six labial probolae often present. Amphids located on lateral lips. Mouth cavity tuboid, generally very narrow, ring elements small, uniformly sclerotized except for the mostly unsclerotized gymnostom; cheilostom wider than the other rings. Dorsal wall of metastom with minute tooth like projection. Pharynx consisting of usual three sections, bulb strong. Vulval opening at two-thirds of body length, ovary reflexed far posterior to vulva, its postvulval section in almost every case with double flexures. Post-uterine sac present, generally short, rarely absent. Males in general nearly as frequent as females. Phasmids distinct.

Type subfamily: Cephalobinae Filipjev, 1934

Other subfamilies: Acrobelinae Thorne, 1937

Acrolobinae De Ley, Siddiqi and Boström, 1993

Metacrobelinae Andrássy, 1974

Subfamily Cephalobinae Filipjev, 1934

Diagnosis: Lip region with simple cephalic and labial probolae, mostly hexaradiate in symmetry, no deep clefts between lips. Cheilostom a broad chamber, gymnostom short, dorsal metastegostom with a small tooth. Pharyngeal corpus cylindrical, basal bulb with well developed grinder. Nerve ring usually surrounding the base of corpus anterior to the isthmus. Female gonad single, reflexed, ovary extending beyond vulva; spermatheca present at anterior flexure of gonad. Males without bursa. Genital papillae present.

Type genus: Cephalobus Bastian, 1865

Other genera: Bunobus De Ley, Siddiqi & Boström, 1993

Eucephalobus Steiner, 1936

Heterocephalobellus Rashid, Geraert & Sharma, 1985

Heterocephalobus (Brzeski, 1960) Brzeski, 1961

Pseudacrobeles Steiner, 1938

Genus Pseudacrobeles Steiner, 1938

Diagnosis: Lateral fields with three incisures, fading out at or near the phasmids.

Lip region with hexaradiate, triradiate or bilateral symmetry and bearing 6+4 papilliform sensillae. Amphids small slits or oval pores at bases of lateral lips.

Lips separate or amalgamated; lateral lips may be reduced. Cephalic probolae absent to short-setiform. Labial probolae absent to low knobs or ridges. Radial ridges absent, tangential ridges present or absent. Mouth opening circular to triangular, occasionally with small radial striae separating small liplet-like structures but never extending deeply between the lips. Stoma with six sets of sclerotizations. Cheilorhabdions comma-, bar- or granule- shaped in optical section; cheilostom wide. Appearance of gymnostom in lateral view varying from being as wide as cheilostom and having sclerotized rhabdia, to being as narrow as stegostom and having inconspicuous rhabdia. Stegostom sections clearly narrower than cheilostom. Females with post-uterine branch usually developed, never surpassing ovary tip. Female tail sharp or blunt, conical, from

2.5 to 10 anal body diam. long. Male tail with or without mucro, with or without

extension of the body core beyond the posteriormost papillae. Gubernaculum with cornua crurum never prominent.

Pseudacrobeles ventricauda sp. n.

(Fig. 1, 2)

Measurements: In Table 1.

Females: Body slender, slightly ventrally curved upon fixation, tapering gradually towards both the ends. Cuticle transversely annulated, annules 1.4-2.0

µm wide at midbody. Lateral fields with three incisures, usually indistinct. Lips separated, lip region with 6+4 papillae. Cephalic probolae setiform. Labial probolae present, low. Stoma cephaloboid. Cheilostom with bar-shaped rhabdia; gymnostom intermediate between cheilostom and stegostom in width and degree of sclerotization. Stegostom narrow with weakly sclerotized rhabdia, metastegostom with a minute dorsal tooth . Pharyngeal corpus cylindrical, 4.5-5.5 times isthmus length. Isthmus visibly demarcated from corpus by transverse markings. Basal bulb pyriform, with grinders. Nerve ring surrounding the posterior part of the corpus, at 65-70% of neck length. Excretory pore opposite nerve ring, at 66-71% of neck length. Hemizonid and excretory pore are at the same level. Intestine with distinct wide lumen. Cardia conoid, enveloped by intestinal tissue.

Reproductive system mono-prodelphic. Ovary reversed, on right side of intestine, with a double flexure or sometimes without any flexure posterior to vulva. Oocytes arranged in one or more rows in the germinal zone and in single or double row in maturation zone. Oviduct short. Spermatheca well developed

1.3 – 2.6 times corresponding body diam. long, containing spermatozoa. Uterus

well developed about 2-3 times the corresponding body diam. long, sometimes with single ova in the lumen. Post-uterine sac 1.2-1.8 times the corresponding body diam. long. Vagina thick-walled, 0.25-0.33 times the vulval body diam. Tail elongate-conoid gradually tapering to a sharply pointed tip. A small subterminal ventral projection is also present near the tail tip.

Males: General appearance similar to that of females. Habitus ventrally curved, more in the posterior region. Reproductive system monorchic. Testis with anterior ventral flexure on right side of intestine. Tail conical bearing an acute mucro. Genital papillae eight pairs; two pairs precloacal (subventral), one adcloacal (subventral) and five pairs postcloacal. Of the five postcloacal pairs, two pairs (one subventral and one lateral) are anterior to phasmid, one subdorsal pair posterior to phasmid and two subventral pairs near the tail terminus. Spicules with rounded manubrium, slightly arcuate lamina and rounded tip. Gubernaculum with well developed crura.

Type habitat and locality: Sandy soil collected from a grass bed near a river close to the Rushikonda beach, Vishakapatnam.

Type specimens

Holotype female on slide Pseudacrobeles ventricauda sp. n./1; ten females and ten males (paratypes) on slides Pseudacrobeles ventricauda sp. n./2-

8 deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Pseudacrobeles ventricauda sp. n. is characterized by setiform cephalic probolae, Cheilostom with bar-shaped rhabdia. Post-uterine sac 1.2-1.8 times the

corresponding body diam. long. Vagina thick walled, 0.25-0.35 times the vulval body diam. Female tail elongate-conoid, with a small subterminal ventral projection and acute tail terminus. Male tail conical, with fine terminal mucro.

The new species resembles Pseudacrobeles variabilis (Steiner, 1936)

Steiner, 1938 in general morphological characters and body size but differs from it in having relatively longer post-uterine branch (36-47 µm vs 16-35 µm), smaller c´ value in females (3.7-4.4 vs 4.6-7.2) and in the shape of female tail

(tail with a sub-terminal ventral projection vs tail terminus straight). The new species also resembles P. tabacum (Rashid, Geraert & Sharma, 1985) De Ley,

Siddiqi & Boström, 1993 in morphological details. However, the new species differs from P. tabacum in having comparatively longer pharynx in males (134-

156 µm vs 115-133 µm long), slightly smaller b-value both in males and females

(3.5-4.0 vs 4.0-4.5 in males and 3.4-4.1 vs 4.2-5.0 in females), longer post-uterine branch 36-47 µm vs 22-31 µm), in the shape of female tail (tail terminus with a ventral projection vs tail terminus without projection) and slightly smaller spicules (19-21 µm vs 21-25 µm).

Table 1: Measurements (in µm) of Pseudacrobeles ventricauda sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 10) (n= 10) L 608 530-620 (587±27) 501-601 (556±34) a 22.5 21.5-24.0 (22.8±0.8) 21.9-27.6 (24.7±1.5) b 3.8 3.4-4.1(3.8±0.2) 3.5-4.0 (3.8±0.2) c 8.5 7.8-8.8 (8.3±0.3) 12.6-14.5 (13.3±0.5) c′ 4 3.7-4.4 (4.2±0.2) 2.0-2.4 (2.2±0.1) V 59.5 57.5-60.5 (59±1.0) -- Maximum body width 26.5 23.5-27.5 (25.5±1.5) 20-25 (22.5±1.5) Lip width 7 6-7 (6.7±0.4) 6-7 (6±0.3) Lip height 4 3-4 (3.9±0.3) 3-4 (3.5±0.5) Length of stoma 13 10-14 (12.5±1.0) 12-13 (12.3±0.5) Corpus 117 99-123 (113±7) 95-115 (105±5) Isthmus 23 20.5-26.5 (24.0±2.0) 18.0-27.5 (23.5±3.0) Basal bulb length 21 18-22 (20±1) 18-19 (18.5±0.5) Pharynx 159 138-166 (155±8) 133-156 (147±8) Excretory pore from ant. end 106 96-114 (106±5) 94-108 (102±4.5) Nerve ring from ant. end 106 96-112 (104±5) 89-106 (98.5±5.0) Dierid from ant. end 124 121.5-133.5 (128±4) 112-126 (119.5±5.0) Cardia 4 4-5 (4.5±0.5) 4.0 Basal bulb width 16 15-17 (15.5±0.5) 13-14 (13.1±0.4) Anterior sac (Spermatheca) 35 32.5-67.5 (46.5±11.5) -- Genital branch 62 62.5-86.0 (76.0±6.5) -- Post-uterine branch 45 36-47 (40.5±4.0) -- VBD 27 23.5-28.5 (26.5±1.5) -- Vulva- anus distance 175 155-189(171±10) -- Rectum/cloaca 20 20-22 (21.0±0.5) 18-21 (19±1.0) Tail 71 64.5-76.0 (70.5±3.5) 37.5-44.5 (42±2.0) ABD 18 15-19 (17±1) 18-20 (18.5±1.0) Phasmids from anus 18 16-21 (19.0±1.5) 17-22 (19.05±1.5) Testis -- -- 224-295 (256±23) Spicules -- -- 19-21 (20±0.5) Gubernaculum -- -- 11-13 (12±0.5)

A B D

C G

E F H

Fig. 2. Pseudacrobeles ventricauda sp. n. A. Anterior region showing stoma, B. Anterior region showing probolae, C. Spermatheca, D. Post-uterine sac, E. Female posterior region, F. Female tail terminus showing ventral projection, G. Spicules and gubernaculum, H. Male posterior region (Scale bars = 20µm).

33 Pseudacrobeles mucronatus sp. n.

(Fig. 3, 4)

Measurements: In Table 2.

Females: Body slightly ventrally curved after fixation. Cuticle about 1.0-1.5 µm thick at mid body, with transverse annules. Annules about 1.7-2.2 µm wide at mid body. Lateral fields occupying 14-22% of mid body diam., with three incisures. Lip region with triradiate symmetry. Cephalic probolae varying from distinctly setiform to completely absent. Labial probolae varying from small but distinct knobs, to flat ridges formed by partially fused lips. Stoma cephaloboid, cheilorhabdia bar shaped. Gymnostom intermediate between cheilostom and stegostom in width and degree of sclerotization. Stegostom with distinguished rhabdia, dorsal metarhabdion with a small tooth like projection. Pharyngeal corpus cylindrical, 4.8-7.5 times isthmus length. Isthmus short 16.0-22.5 µm long, Basal bulb pyriform, with well developed valves. Nerve ring lying in the corpus region, at 57-78% of pharynx length. Excretory pore at the level, or upto five annules posterior to the trailing edge of nerve ring. Dierid 4-7 annules posterior to excretory pore. Cardia short, conoid surrounded by intestinal tissue.

Reproductive system mono-prodelphic, ovary directed posteriorly, with oocytes generally arranged in one or two rows in the germinal zone and in a single row in maturation zone. Oviduct short. Spermatheca well developed 0.5-

1.5 times corresponding body diam long. Uterus tubular, differentiated into anterior glandular part, and posterior muscular part with distinct lumen. Post- uterine sac 0.8-1.3 vulval body diam. long. Vagina thick walled. Vulva transverse

slit like. Rectum 1.2-1.6 anal body diam. long. Tail elongate conoid, 3.5-4.5 anal body diam. long, with acute terminus. Phasmid at 23-34% of tail length.

Males: Anterior region of males similar to that of females. Variability in the lip region is also in concurrence with females. Habitus ventrally curved, more in the posterior region giving it a ‘J’ shaped appearance. Reproductive system monorchic. Testis ventrally reflexed anteriorly, with flexure on right side of intestine. Tail conoid with mucronate tip. Mucro either small (with blunt tip) or long (with pointed tip). Genital papillae eight pairs; two pairs precloacal

(subventral), one adcloacal (subventral) and five pairs postcloacal. Of the five postcloacal pairs, two pairs (one subventral and one lateral) are anterior to phasmid, one dorsal pair posterior to phasmid and two subventral pairs near the tail terminus. Spicules cephaloboid, rounded manubrium, calamus slightly narrower than manubrium, lamina ventrally curved, with acute terminus.

Gubernaculum with well developed crura.

Type habitat and locality: Decaying organic matter and leaf litter collected from

Indira Gandhi Zoological Park, Vishakapatnam, Andhra Pradesh, India.

Type specimens

Holotype female on slide Pseudacrobeles mucronatus sp. n./1; nine females and six males (paratypes) on slides Pseudacrobeles mucronatus sp. n. /2-

6, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Pseudacrobeles mucronatus sp. n. is characterized by three incisures in lateral fields. Cephalic probolae varying from distinctly setiform to completely

absent. Labial probolae varying from small but distinct knobs to flat ridges.

Cheilorhabdia bar shaped. Gymnostom intermediate between cheilostom and metastegostom in width and degree of sclerotization. Pharyngeal corpus cylindrical, 4.8-7.5 times isthmus length. Males with mucronate tail tip. Mucro either small (with blunt tip) or long (with pointed tip). Gubernaculum with well developed crura.

The new species closely resembles Pseudacrobeles variabilis (Steiner,

1936) Steiner, 1938 in general morphological characters and body size. However, new species differs from it in having smaller c´ value in females (3.6-4.5 vs 4.8-

7.2), larger corpus to isthmus ratio (4.8-7.5 vs 3.1-4.5 in females and 5.7-6.4 vs

3.1-4.2 in males) and slightly longer gubernaculum (12-14 µm vs 10-12 µm). The new species also resembles P. baloghi Andrassy, 1968 in body size, shape of lip region and morphometric values. However, the present species differs from P. baloghi in having longer body in males (0.52-0.58 mm vs 0.4-0.51), smaller c´ value (2.0-2.4 vs 2.8-3.7), larger corpus to isthmus ratio (4.8-7.5 vs 2.9-4.2 in females and 5.7-6.4 vs 3.2-4.0 in males), more posterior position of phasmid in males (20-24 vs 13-19), in shape of male tail (mucronate tail tip vs tail tip with body core extending in spike for 4-11µm) and slightly longer gubernaculum (12-

14 vs 10-12).

P. mucronatus sp. n. closely resembles P. tabacum Rashid et al., 1985 in general morphometrics and morphology. However, differences were traced in the shape of cheilostom (never in granular form vs bar to granule form), longer pharynx in males (150-163 vs 115-131), smaller b value (3.2-4.0 vs 4.2-5.0 in females and 3.3-3.6 vs 4.0-4.6 in males), position of nerve ring in females (57-72

% vs 73-74 % of the pharynx length), larger corpus to isthmus ratio in males (5.7-

6.4 vs 4.1-4.7). The new species also resembles P. laevis Thorne, 1937 in body size, structure of cephalic and labial probolae and other morphological details.

However, differences were found in ‘a’ value (20.7-23.5 vs 24-28 in females and

19.5-23.8 vs 25-29 in males), ‘c’ value of females (8.3-10.0 vs 11-14) and corpus:isthmus ratio (4.8-7.5 vs 3.3-4.5 in females and 5.7-6.4 vs 3.2-4.1 in males).

Table 2: Measurements (in µm) of Pseudacrobeles mucronatus sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 9) (n= 6) L 534 492-640 (558±41) 518-583 (538±22) a 20.7 20.7-23.5 (22.1±1.0) 19.5-23.8 (21.6±1.4) b 3.5 3.2-4.0(3.8±0.2) 3.3-3.6 (3.4±0.1) c 9.6 8.3-10.0 (9.4±0.7) 12.0-13.2 (12.7±0.4) c′ 3.7 3.6-4.5 (4.0±0.3) 2.0-2.4 (2.2±0.1) V 65.5 61.5-65.5 (63.5±1.5) -- Maximum body width 25.5 21.8-28.7 (25.0±2.0) 22.5-26.5 (25.0±1.5) Lip width 7 7-8 (7.3±0.5) 7-8 (7.3±0.5) Lip height 4 4-5 (4.2±0.4) 4.0 Length of stoma 13 13-15 (13.5±0.6) 13-14 (13.2±0.5) Corpus 119 100-133 (120±9) 114-124 (120±4) Isthmus 16 15.5-22.5 (20±2) 18-22 (19.5±1.5) Basal bulb length 20 19-24 (20.5±1.5) 18-20 (19±0.7) Pharynx 153 140-176 (159±10) 150-163 (158±5) Excretory pore from ant. end 102 94-114 (103±5) 104-110 (105±2) Nerve ring from ant. end 99 92-110 (101±5) 95-106 (100±3.5) Dierid from ant. end 118 106-127 (116±6) 114-124 (117±3.5) Cardia 4 4-5 (4.3±0.5) 4-5 (4.1±0.4) Basal bulb width 16 14-18 (15±1.0) 14-16 (14.8±0.8) Anterior sac (Spermatheca) 36.5 12-38 (37±8) -- Genital branch 64 48.5-77.0 (61.5±8.5) -- Post-uterine branch 29.5 17.5-38.5 (28.5±6.0) -- VBD 25.5 22.0-28.5 (25.5±2.0) -- Vulva- anus distance 128 127-159 (144±11) -- Rectum/cloaca 19 19-21 (20.0±0.5) 17-20 (18.5±1.5) Tail 55.5 53.5-67.5 (59.5±4.0) 39.5-44.5 (42.5±1.5) ABD 15 13-17 (15±1) 18-20 (19±0.5) Phasmids from anus 16 14-22 (17.0±2.5) 20-24 (22±1.5) Testis -- -- 208-268 (229±21) Spicules -- -- 22-24 (23±0.7) Gubernaculum -- -- 12-14 (13.2±0.7)

A B C

I J H

Fig. 4. Pseudacrobeles mucronatus sp. n. A-C. Anterior region showing variable lip region and stoma, D. Spermatheca, E. Post-uterine sac, F. Female posterior region, G. Lateral lines, H. Male posterior region, I&J. Male tail tip showing variable mucro length (Scale bars = 20µm).

40 Subfamily Acrobelinae Thorne, 1937

Diagnosis: Lip region having cephalic probolae with complicated structures, labial probolae large and exhibit triradiate symmetry, deep clefts present between the lips. Cheilostom a broad chamber, gymnostom short, dorsal metastegostom with a small tooth. Pharyngeal corpus cylindrical, basal bulb with well developed grinder. Nerve ring usually surrounding the base of corpus or anterior half of isthmus. Female gonad single, reflexed, ovary extending beyond vulva, straight or with flexure posterior to vulva; spermatheca present at anterior flexure of gonad. Males without bursa. Genital papillae present.

Type genus: Acrobeles Linstow, 1877

Other genera: Acrobeloides (Cobb, 1924) Thorne, 1937 Acrobelophis Andrassy, 1984 Acroukrainicus Holovachov, Boström & Susulovsky, 2001 Cervidellus Thorne, 1937 Chiloplacoides Heyns, 1994 Chiloplacus Thorne, 1937 Nothacrobeles Allen & Noffsinger, 1971 Paracrobeles Heyns, 1968 Pentjatinema Heyns & Swart, 1998 Placodira Thorne, 1937 Scottnema Timm, 1971 Stegelleta Thorne, 1938 Stegelletina Andrassy, 1984 Triligulla Siddiqi, 1993 Zeldia Thorne, 1937

Genus Acrobeles Linstow, 1877

Diagnosis: Body small to large (L=0.3-1.1 mm). Cuticle single or double, with large annules, with or without longitudinal striae, punctations and/or pores.

Lateral field with two or three incisures, if cuticle double then often with undulating internal pseudolines. Amphids relatively distinct, circular. Labial probolae long, deeply bifurcated. Each prong with at least seven tines, its tip usually with two elongate , separated apical tines.cephalic probolae high, triangular, separate and fringed by numerous tines. Stoma cephaloboid with distinct cheilorhabdia that are large and spherical in cross section. Pharyngea corpus cylindrical to fusiform. Excretory pore position varying from very anterior to opposite basal bulb. Female reproductive system cephaloboid, spermatheca and post-uterine sac small to large. Vulva flush with body, occasionally sunken.

Males with three pairs of precloacal papillae, five pairs of postcloacal papillae and one median papillae on the precloacal lip. Tails in both sexes conical, usually with acute tip.

Acrobeles mariannae Andrassy, 1968

(Fig. 5)

Measurements: In Table 3.

Females: Body, straight to slightly curved ventrad, gradually tapering at both extremities. Cuticle double, both layers similar, coarsely annulated. Annules about 1.5-2.0 µm wide at mid body. Lateral fields with four incisures, slightly elevated from body contour, outer incisures smooth, inner ones are crenate.

Labial probolae 7-11 µm high, bifurcated to about 50-60% of their length, each

arm bearing membranous tines varying in length and shape, rounded to rod-like, and apical ones longer than the posterior ones. Inner sides with 6-8 tines and outer sides with 7-9 tines, terminal tines ‘T’ shape. Cephalic probolae forming a circle around the labials, each probola triangular, flap like, with 7 or 8 tines at primary and secondary axil margins. Primary and secondary axils with similar morphology (‘U’ shaped), with two guard processes each. Third tine of the secondary axil is long and forwardly directed. Amphidial apertures rounded, at the base of lateral cephalic probolae. Stoma cephaloboid, rhabdia distinctly demarcated, cheilostom wide, with rounded rhabdia, gymnostom narrower than cheilostom and as wide as stegostom, dorsal metarhabdion with tooth. Pharyngeal corpus cylindrical 4-8 times longer than isthmus. Isthmus short, distinctly separated from corpus by transverse marking. Basal bulb pyriform, with well developed grinders. Nerve ring surrounding the corpus near corpus-isthmus junction, at about 66-71% of pharynx length. Excretory pore far forward 26-38

µm from anterior end. Hemizonid in the posterior half of isthmus. Dierids at the level of basal bulb. Cardia short, conoid surrounded by the intestinal tissue.

Intestine with small and granular cells, and wide lumen.

Reproductive system mono-prodelphic, ovary reversed, with or without double flexure posterior to vulva. Oocytes arranged in one or two rows in the germinal zone and in a single row in proliferative zone of ovary. Oviduct short.

Spermatheca reduced, less than the corresponding body diam. in length. Uterus tubular, more than two corresponding diam. long, differentiated into a proximal glandular and a distal muscular with thin walls. Post-uterine sac small, less than the vulval body diam. in length. Vagina tubular, perpendicular to body axis, one

third of body diam. long. Vulva a transverse slit. Rectum 1.0-1.3 anal body diam. long, anus an arcuate transverse slit. Tail conoid, gradually narrowing to an acute terminus. Phasmids distinct, 33-39% or about one anal body diam. posterior to anus.

Male: Not found.

Habitat and locality: Soil collected from the barren fields and road side ditches near All India Radio station, Anoopshahr road, Aligarh.

Voucher specimen

Twelve females on slides Acrobeles mariannae/1-5 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Remarks

A. mariannae is a terrestrial species. It is widely distributed and is known from The Netherlands, Hungary, Pakistan, Sudan, Kenya, Namibia, South Africa,

Brazil, Paraguay and Krakatau Islands, Hungary. This species is easily differentiated from the other species of the genus by its small body and a very anteriorly located excretory pore. The morphology and morphometric values of our population of A. mariannae corresponds well with those of described populations. A. mariannae is reported for the first time from India.

Table 3: Measurements (in µm) of Acrobeles mariannae Andrassy, 1968 Mean and S.D. given in parenthesis

Characters Females (n=10) L 440-497 (472 ± 20) a 15.7-18.3 (16.9 ± 1) b 3.6-4.1 (3.9 ± 0.15) c 9.5-11.9 (10.6 ± 0.6) c′ 2.3-3.0 (2.6 ± 0.2) V 60-62 (61 ± 0.5) Maximum body width 25-30 (28 ± 1.5) Lip width 13-14 (13.1 ± 0.4) Stoma length 11-14 (11.5 ± 1) Corpus 79-86 (84 ± 2) Isthmus 11-22 (16 ± 4) Basal bulb length 21-23 (21.5 ± 0.5) Basal bulb width 15-18 (16 ± 1) Pharynx 114-128 (122 ± 5) Excretory pore from anterior end 26-38 (33 ± 3.5) Nerve ring 74-89 (82 ± 4) Cardia 5-6 (5.5 ± 0.5) Anterior sac (Spermatheca) 6-13 (9 ± 2) Genital branch 46.5-79.0 (63 ±10) Post-uterine sac 9-16 (13.5 ± 2) Vulval body diameter (VBD) 24-30 (28 ±1.5) Vulval anus distance 131-153 (141 ± 8.5) Rectum 18-20 (19 ± 1) Tail 41-48 (45 ± 2) Anal body diameter (ABD) 15-19 (17 ± 1.5) Phasmids from anus 15-17 (16 ± 0.5)

Genus Acrobeloides (Cobb, 1924) Thorne, 1937

Diagnosis: Body length varying from 0.3-1.2 mm. cuticle annulated, lateral fields with two to five incisures extending generally to tip of tail. Lips three, labial probolae hemispheroid or conoid, point always uni-tipped. Cephalic probolae present, but low, not strongly differentiated. Proximal half of oesophagous, fusiform. Stoma cephaloboid, narrow. Vulva near two-thirds of body length, ovary with double postvulval flexures. Males mostly unknown. Tail short and plump, broadly rounded or conoid.

Acrobeloides glandulatus sp. n.

(Fig. 6, 7)

Measurements: In Table 4.

Females: Body cylindrical, tapering gradually towards both ends, slightly ventrally curved after fixation. Cuticle with strong transverse annules, annuli 3-

4µm wide at midbody. Lateral fields 22-30% of the mid-body diam., with five incisures; outer incisures crenate and irregularly aerolated. Lips six, amalgamated in pairs, flattened. Primary axils distinct, with smooth margins. Secondary axils scarcely demarcated. Three low and rounded labial probolae. Amphidial apertures slit-like. Stoma cephaloboid. Cheilostom wide, with small and ovoid rhabdia, gymnostom and stegostom slightly narrower than cheilostom, metastegostom with a small tooth on dorsal rhabdia. Pharyngeal corpus cylindrical, 4.7-7.5 times isthmus length. Corpus-isthmus junction distinguished by transverse markings. Isthmus smaller than basal bulb. Basal bulb ovoid or pyriform, with strongly developed grinder. Nerve ring surrounding the isthmus in

anterior half, or at 73-78% of neck length. Excretory pore at the level of basal bulb, 77-92% of neck length. Dierids at level or slightly posterior of basal bulb region. Cardia conoid, surrounded by intestinal tissue. Intestine with distinct wide lumen, intestinal cells small, granular in appearance with distinct nuclei.

Reproductive system mono-prodelphic. Ovary reversed, straight or with double flexure in its postvulvular part. Oocytes arranged in two or more rows in the germinal zone. Oviduct short, tubular. Spermatheca 0.6-2.0 times the corresponding body diam. long, with few sperms. Uterus long, differentiated in an elongated proximal glandular part and a short distal muscular part with wide and distinct lumen. Post-uterine sac 1-2 vulval body diam. long. Vagina with thick walls, one-third of body diam. A pair of spheroid glands associated with the vagina, each gland is arranged on either side of vagina, both glands seems to open into the vaginal lumen through a common duct. Vulva transverse, lips slightly protruded. Rectum less than one anal body diam. long. Tail conoid, 1.7-

2.1 anal body diam. long, with rounded terminus. Phasmid at 46 – 55 % of tail length.

Males: General appearance similar to that of female, but with slightly smaller body, ventrally curved in the posterior region adopting ‘J’ shape. Reproductive system monorchic. Testis reflexed ventrally anteriorly on the right side of intestine. Tail conoid, ventrally curved, with rounded terminus. Genital papillae eight pairs; three pairs pre-cloacal (subventral), five pairs post-cloacal. Of the five post-cloacal pairs two pairs (one subventral and one lateral) anterior to phasmid, three pairs (one dorsal, one lateral and one subventral) near the tail terminus. Spicules strong, small manubrium, calamus broad, slightly ventrally

curved lamina with pointed tip. Gubernaculum straight, more than half of spicule length, narrow and pointed distally.

Type habitat and locality: Soil collected from a ploughed field at Nohati village,

Madrak, Aligarh.

Type specimens

Holotype female on slide Acrobeloides glandulatus sp. n./1, nine females and eight males (paratypes) on slides Acrobeloides glandulatus sp. n./2-10 deposited in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationship

Acrobeloides glandulatus sp. n. is characterized by a body length of 625-

825 µm in females and 558-717 µm in males. Lateral fields with five incisures.

Low and rounded labial probolae. Pharyngeal corpus 4.7-7.5 times isthmus length. Well developed spermatheca (0.6-2.0 times corresponding body diam. long) and long post-uterine sac (1-2 vulval body diam. long). Presence of one pair of gland on either side of vagina. Spicules 41-48 µm long. Straight gubernaculum, with narrow and pointed distal end.

The new species resembles Acrobeloides bodenheimeri (Steiner, 1936)

Thorne, 1937 in general morphological characters, morphometric values and body size but differs from it in having longer post-uterine sac (57-72 µm vs 29-55

µm), variable shape of ovary (with or without double flexure vs with double flexure), larger corpus-isthmus ratio (5-8 vs 3.8-4.2), longer spicules (41-48 µm

vs 35-39 µm) and in the shape of gubernaculum (straight and pointed distal tip vs ventrally curved and blunt distal tip).

Table 4: Measurements (in µm) of Acrobeloides glandulatus sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 9) (n= 8) L 825 625-825 (746±58.5) 558-717 (644±53) a 17 15.8-19.3 (17.6±1.2) 14.5-18.2 (16.2±1.2) b 5.4 4.5-5.5 (5.1±0.3) 4.3-5.1 (4.9±0.2) c 19 15.4-19.0 (17.3±1.2) 14.5-17.0 (15.5±0.9) c´ 1.9 1.7-2.1 (1.9±0.13) 1.5-1.8 (1.6±0.1) V 69 68-71 (69.5±1.0) -- Maximum body width 47 32.5-50.5 (43.0±6.0) 30.5-47.5 (40.0±4.5) Lip width 12 11-13 (11.5±0.7) 10-12 (11.0±0.5) Lip height 5 5-6 (5.4±0.5) 5-6 (5.1±0.3) Length of stoma 14 13-14 (13.7±0.5) 13-14 (13.2±0.4)) Corpus 109 102-110 (105.5±3.0) 81-106 (93.5±7.0) Isthmus 17 14-22 (17±2.5) 15-20 (17±20) Basal bulb length 26 22.0-26.5 (24.5±1.5) 19.0-23.5 (21.5±2.0) Pharynx 153 138-152 (146±5) 120-146 (132±9) Excretory pore from ant. end 126 115-130 (124±5.5) 101-130 (115±11) Nerve ring from ant. end 112 103-113 (109±3.5) 85-102 (96±6) Dierid from ant. end 136 126-141 (133.5±5.5) 108-138 (124±10) Anterior sac (Spermatheca) 54 23-72 (44±13) -- Genital branch 215 137-274 (206±41) -- Post-uterine branch 59 57-72 (64±6) -- VBD 42 32.5-50.5 (41±5.5) -- Vulva- anus distance 214 160-214 (184±16) -- Rectum/cloaca 25 20-26 (24.5±1.5) 33-41 (36±2) Tail 43 40.5-45.5 (43.5±1.5) 36.5-44.5 (41±2.0) ABD 23 19-25 (22.5±1.5) 20.5-29.5 (25.5±2.5) Phasmids from anus 20 20-25 (21.5±2.0) 20-27 (24±2) Testis -- -- 294-381 (343±32) Spicules -- -- 40.5-47.5 (43.5±2.5) Gubernaculum -- -- 21.5-27.5 (25.5±2.0)

A B C

F I

G H J

Fig. 7. Acrobeloides glandulatus sp. n. A&B. Anterior region showing stoma and lip region, C. Glands associated with vagina, D. Vulval region, E&F. Cuticular markings, G&H. female posterior region, I&J. Male posterior region showing spicules and gubernaculum (Scale bars = 20µm).

53 Genus Cervidellus Thorne, 1937

Diagnosis: Very small nematodes ranging from 0.3 to 0.5mm. Cuticle finely annulated, lateral fields with two, three or five incisures. Lip margins with U- shaped refractive elements, cephalic probolae six, triangular or leaf-like. Labial probolae thin, Y-shaped, occasionally with secondary tines. Pharyngeal corpus cylindrical. Female genital apparatus cephaloboid. Tails of both sexes conoid with pointed tip.

Cervidellus neoalutus sp. n.

(Fig. 8, 9)

Measurements: In Table 5.

Females: Body slender, slightly ventrally curved after fixation, gradually tapering towards both extremities. Cuticle double, transversely annulated, each annule with two rows of punctations. Annuli 1.8-2.2 µm wide at pharyngeal region and about 1.7-2.0 µm wide at midbody and tail region. Lateral fields with four crenated incisures, without areolation, covering about 1/5th of body diam. at midbody. Lateral lines start at 40-50% of pharynx length from anterior end as two faint lines and differentiate into four lines at level of basal bulb. The two inner incisures are more widely separated as compared to the outer ones, appearing as two pairs of four lines. All incisures reach the tail terminus.

Cephalic region with six probolae, each consisting of five leaf-like elements: in the centre, the longest and slightly clavate element; more outwards and on both sides two pairs of shorter and acute elements. Labial probolae about 5µm long with bifurcation at two levels, primary bifurcation at 2/3rd of probolae length,

secondary bifurcation apical. Amphidial apertures small, rounded. Stoma cephaloboid. Cheilostom wide, with granular rhabdia. Gymnostom and stegostom with less distinct rhabdia, narrower than cheilostom. Dorsal metastegostom with a minute tooth like projection. Pharyngeal corpus cylindrical 2.5-3.0 times isthmus length. Basal bulb pyriform or ovoid with well developed grinder. Nerve ring at 63-71 % of neck length, surrounding isthmus in its anterior half. Excretory pore at the level or slightly anterior to nerve ring. Dierids in the isthmus region, at

71-78% of neck length. Cardia rounded to conoid, surrounded by intestinal tissue.

Intestinal walls with differentiated rectangular cells, intestine with wide lumen.

Reproductive system mono-prodelphic. Ovary reversed, extending posterior to vulva, postvulval flexure absent. Oocytes with large nuclei, arranged in a single or double row in the germinal zone and in a single row in the maturation zone. Oviduct short, spermatheca well developed, about 1.5 vulval body diam. long. Uterus simple, tubular with narrow lumen and without any differentiation. Post-uterine sac 1.0-2.5 times vulval body diam. long. Vagina narrow, tubular, one-fourth of body diam. Vulval opening a small transverse slit.

Tail conical, with acute terminus. Phasmids distinctly visible, about 0.6-1.0 anal body diam. posterior to anus.

Males: Anterior region similar to that of females. Reproductive system monorchic. Testis reflexed ventrad anteriorly, on right side of intestine. Spicules cephaloboid, manubrium round, calamus slightly narrower than manubrium, lamina ventrally curved, with acute terminus. Gubernaculum straight, with well developed crura. Genital papillae seven pairs, three pairs precloacal (subventral) and four pairs postcloacal. Out of the four postcloacal papillae, two pairs (one

subventral & one lateral) anterior to phasmid and two pairs (one subdorsal & one lateral) posterior to phasmid. A mid-ventral papilla on the anterior cloacal lip is also present.

Type habitat and locality: Soil from a barren field near Central School, Bad village, Mathura.

Type specimens

Holotype female on slide Cervidellus neoalutus sp. n./1, nine females and three males (paratypes) on slides Cervidellus neoalutus sp. n./2-8 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Diagnosis and relationship

Cervidellus neoalutus sp. n. is characterized by a double cuticle, lateral fields with four crenate incisures with inner ones more widely separated than outer ones. Symmetrical lips, with refractive elements, labial probolae with bifurcation at two levels and small post-uterine sac about 1.2-2 times vulval body diam. in length.

The new species closely resembles C. alutus (Siddiqi, 1993) Shahina and

De Ley, 1997 in having double cuticle, symmetrical lips with refractive elements but differs from it in the length of stoma (14-15 µm vs 10 µm), smaller post- uterine sac (1.2 – 2 vs 2.3 - 2.6 times vulval body diam. long) and in the presence of males (males absent in C. alutus).

Table 5: Measurements (in µm) of Cervidellus neoalutus sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 9) (n= 3) L 554 485-566 (529.5±23) 500-538 (522±16.5) a 20.7 18.3-22.3 (20±1.3) 17.5-19 (18.5±0.7) b 3.9 3.5-3.9 (3.7±0.2) 3.5-4.0 (3.8±0.2) c 10.4 9.8-11.3 (10.3±0.4) 13.5-14.5 (14±0.5) c’ 3.2 2.7-3.3 (3.1±0.2) 1.8-2.0 (1.9±0.1) V 59 57-59 (58.5±0.5) -- Maximum body width 26.5 22-31 (26.5±2.3) 28-29 (28.5±0.5) Lip width 13 12-13 (12.5±0.5) 12-13 (12.5±0.5) Lip height 7 6-7 (6.5±0.5) 7 Length of stoma 14 14-15 (14.5±0.5) 14 Corpus 86 85-90 (87±1.5) 85-87 (86.5±1.0) Isthmus 32.5 27.5-33.5 (31.5±2.0) 24.5-31.5 (28.5±3.0) Basal bulb length 22.5 21-24 (23±1.0) 22-24 (22.5±1.0) Pharynx 141.5 135-145 (142±3.5) 136-141(138±4) Excretory pore from ant. end 96 84-96 (92±3.5) 96-97 (96.5±0.5) Nerve ring from ant. end 101 87-101 (94±3.5) 92-96 (94.5±1.5) Dierid from ant. end 111 98-112 (107±5) 110 Basal bulb width 15 14-16 (15.5±0.5) 15-16 (15.2±0.5) Anterior sac (Spermatheca) 37.5 29-43.5 (37±4.5) -- Genital branch 51 44.5-63.5 (50.5±5.5) -- Post-uterine branch 51 35.5-59.5 (47±7) -- VBD 27 22-31 (26±2.5) -- Vulva- anus distance 173 157-179 (167±7) -- Rectum 18 15-20 (18±1.5) -- Tail 53 48.5-55.5 (52±2.5) 37-39 (37.5±1.0) ABD 17 15-19 (17±1) 20-21 (20.2±0.5) Phasmids from anus 17 11-17 (15±2) 15-17 (16±1.0) Testis -- -- 229-274 (246 ± 20) Spicules -- -- 22-23 (22.5±0.5) Gubernaculum -- -- 12-13 (12.5±0.5)

A B C

D E G

F I H

Fig. 9. Cervidellus neoalutus sp. n. A. Anterior region showing amphidial aperture, B&C. Anterior region showing probolae and stoma, D. Spermatheca, E. Post-uterine sac, F. Female posterior region, G. Male posterior region, H. Spicules and gubernaculum, I. Lateral lines (Scale bars = 20µm).

59 Cervidellus minutus sp. n.

(Fig. 10, 11)

Measurements: In Table 6.

Females: Body small, slightly ventrally curved after fixation. Cuticle simple, with transverse annulations. Lateral fields 12-14% of mid-body diam. wide, with three incisures. Outer incisures crenate extending up to tail tip, central incisure ends at phasmids. Cephalic probolae six, with refractive margins, each consisting of five leaf- like elements. Primary and secondary axils similar in shape. Labial probolae reduced, rarely visible in light microscope. Amphidial apertures small, ovoid.

Cheilostom with granular rhabdia, gymno- and stego-rhabdions poorly developed. Pharyngeal corpus slightly fusiform, sometimes with wide lumen, 3.1-

3.7 times isthmus length. Corpus-isthmus junction distinguished by faint transverse markings. Basal bulb spheroid, with well developed grinder. Nerve ring at 56-61% of neck length, encircling isthmus in its anterior half. Excretory pore at the level or just posterior to corpus-isthmus junction. Excretory duct distinctly sclerotized. Dierids in the isthmus region or at the level of basal bulb.

Intestine with wide lumen. Cardia conoid about 2-3µm long, surrounded by intestinal tissue.

Reproductive system mono-prodelphic, on right side of intestine. Ovary reversed, without flexure posterior to vulva. Oocytes arranged in a single or double row in germinal zone and in a single row in proliferative zone. Oviduct short, not clearly demarcated. Spermatheca weakly developed, smaller than the corresponding body diam. Uterus uniform in thickness, without any differentiation between glandular and muscular part, lumen not visible. Post-

uterine sac less than one vulval body diam. long. Vagina straight, about 1/3rd of body diam. with slightly thickened walls. Vulva transverse, slit like. Rectum slightly more than one anal body diam. long. Rectal glands barely visible. Tail conical, about 2-3 anal body diam. long, terminus acute, with subterminal dorsal projection. Phasmids with distinct opening, about half anal body diam. posterior to anus.

Male: Not found.

Type habitat and locality: Collected from the rhizosphere of Guava (Psidium guajava) and Cashew-nut (Anacardium occidentale), in mixed plantation, from

Satpada, near Chilka lake, Orrisa, India.

Type specimens

Holotype female on slide Cervidellus minutus sp. n./1 and five females

(paratypes) on slides Cervidellus minutus sp. n./2-4 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University, Aligarh.

Diagnosis and relationship

Cervidellus minutus sp. n. is characterized by its small body (226-266

µm), lateral fields with three incisures. Lips with refractive margins. Reduced labial probolae. Distinctly sclerotized excretory duct. Small spermatheca (5-6

µm) and post-uterine sac (less than one anal body diam.). Conoid tail, with acute terminus and hook-like subterminal dorsal projection.

The new species differs from all other species of the genus in having a subterminal dorsal projection in female tail. It, however, closely resembles C. neftasiensis Boström, 1986 and C. vexilliger (de Man, 1880) Thorne, 1937 in general morphometrics, shape of labial region, number of lateral lines. It can be

differentiated from C. neftasiensis in having comparatively smaller body length

(226-266 µm vs 268-330 µm), smaller spermatheca (5-6µm vs 13-28µm), and relatively smaller genital branch (26-36µm vs 37-71µm). C. minutus sp. n. also differs from C. vexilliger in having smaller spermatheca (5-6 µm vs 11-37 µm) and relatively smaller post-uterine branch (7-8 µm vs 8-47 µm).

Table 6: Measurements (in µm) of Cervidellus minutus sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Characters female (n= 5) L 253 226-266 (251±13) a 17 16.3-18.8 (17.1±0.8) b 3 2.9-3.1 (3±0.1) c 12.2 10.5-12.2 (11.5±0.6) c’ 2.3 2.3-2.8 (2.5±0.1) V 67 63.5-66.5 (64.5±1.0) Maximum body width 15 14-16 (14.5±0.5) Lip width 8 8-9 (8.5±0.5) Lip height 5 5-6 (5.2±0.5) Length of stoma 7 6-8 (7±0.5) Corpus 56 50.5-56.5 (55±2) Isthmus 16 14-18 (16±1.5) Basal bulb length 13 12-13 (12.5±0.5) Pharynx 85 77-86 (83.5±3) Excretory pore from ant. end 53 51.5-59.5 (54.5±2.5) Nerve ring from ant. end 48 47.5-51.5 (49.5±1.5) Dierids from ant. end 67 67.5-69.5 (67.5±1) Basal bulb width 9.9 9.9 Anterior sac (Spermatheca) 5 5-6 (5.5±0.5) Genital branch 32 26-36 (31±4.5) Post-uterine branch 8 7-9 (7.5±0.5) VBD 14 13-15 (13.5±0.5) Vulva- anus distance 63.5 61-73 (67±4) Rectum 12 10-12 (11.5±1.0) Tail 21 20-24 (22±1.5) ABD 9 8-10 (8.5±0.5) Phasmids from anus 5 4-5 (4.2±0.4)

A B C

D E

Fig. 11. Cervidellus minutus sp. n. A. Pharyngeal region, B Anterior region showing cephalic probolae with refractive margins, C Anterior region showing stoma, D. Lateral lines, E Female reproductive system, F. Posterior region, G. Tail tip showing dorsal projection (Scale bars = 20µm).

65 Genus Chiloplacus Thorne, 1937

Diagnosis: Body 0.3-1.0 mm long. Cuticle annulated, lateral fields with 3-6 lines.

Lips three. Labial probolae biacute or bifurcate (apically incised), symmetrical or assymetrical, with broad “shafts”. Cephalic probolae small, generally with two incisures. Pharyngeal corpus cylindrical. Post-vulval uterine sac of variable lengths. Female tail straight, short, cylindroid, terminus broadly rounded. Male tail ventrally bent, phasmids posterior to lateral caudal papilla.

Chiloplacus aligarhensis sp. n.

(Fig. 12, 13)

Measurements: In Table 7.

Females: Body slender, straight or slightly ventrally curved after fixation. Cuticle annulated, annules 2.3-3.3 µm wide at mid-body, with irregular punctations throughout the body length. Lateral fields about 1/4th body diam. at midbody, with five incisures. Lateral lines arise at about two stoma lengths from anterior end and from middle of procorpus differentiate into five lines that extends upto the tail terminus except the central incisure that ends at phasmids. Lip region with six lips. Cephalic probolae small, with deep primary axils and shallow secondary axils. Labial probolae high (6-7µm), with shallow bifurcation forming finely developed prongs. Stoma cephaloboid, rhabdions clearly differentiated; cheilostom wide with minute oval or triangular rhabdia, gymnostom slightly narrower than cheilostom and as wide as stegostom, metastegostom with small tooth like projection. Pharyngeal corpus cylindrical, 8-11 times isthmus length.

Corpus-isthmus junction demarcated by faint transverse markings. Isthmus short,

17-22 µm long, basal bulb ovoid, with well developed grinder. Nerve ring surrounding corpus in its posterior half, at 60-66% of pharynx length. Excretory pore at 60-72% of pharynx length. Dierids 5-8 annules posterior to excretory pore. Cardia short, conoid, surrounded by intestinal tissue. Intestine with wide lumen and thin walls in its anterior region, cell differentiation not visible in anterior and posterior regions of intestine. Cells in the mid-intestine region well differentiated, rectangular in shape, granular in appearance with distinct nuclei.

Reproductive system mono-prodelphic, ovary reversed, without flexure posterior to vulva, sometimes with swollen germinal portion with oocytes arranged in one or two rows. Oocytes in a single row in the proliferative zone.

Oviduct short. Spermatheca well developed, longer than the corresponding body diam.. Uterus tubular, more than two corresponding body diam. long, differentiated into a proximal glandular part and a distal swollen muscular part with thin walls. Post-uterine sac well developed, 2.5-4.0 vulval body diam. long.

Vagina muscular, anteriorly inclined, about half of vulval body diam. long. Vulva transverse, slit-like, vulval lips may be slightly protruded. Rectum 1.0-1.3 anal body diam. long. Tail subcylindrical with rounded terminus. Phasmids distinct,

1.0-1.5 anal body diam. posterior to anus.

Males: General morphology similar to that of females. Body J-shaped after fixation. Reproductive system monorchic. Testis reflexed ventrally anteriorly, with flexure on right side of intestine. Apical germinative zone with three to four rows of spermatogonia, maturation zone with spermatocytes and differentiated sperms at its distal end. Vas deferens highly granular in appearance without any valve or sphincter at the junction of maturation zone. Ejaculatory duct with

similar appearance as of vas deferens but with distinct lumen containing sperms.

Tail conoid, ventrally curved. Genital papillae eight pairs; three pairs pre-cloacal, ventro-lateral in position and five pairs post-cloacal. Of the post-cloacal pairs, one ventro-lateral and one lateral pair anterior to phasmids, one pair dorso-lateral near tail terminus and two terminal ventro-lateral pairs. A single median precloacal papilla present on the anterior cloacal lip. Spicules slightly ventrally arcuate, manubrium round and bent ventrally, calamus with thin walls, lamina thick, ventrally curved, bearing a longitudinal incisure from the calamus,

Gubernaculum well developed, trough-shaped, about half of spicule length, with serrated margins at its proximal end.

Type habitat and locality: Soil around the rhizosphere of grasses from a barren field near village Lodha on Aligarh-Khair road.

Type specimens

Holotype female on slide Chiloplacus aligarhensis sp. n./1, ten females and eleven males (paratypes) on slides Chiloplacus aligarhensis sp. n./2-11 deposited in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationship

Chiloplacus aligarhensis sp. n. is characterized by the long body (0.75-

0.83 mm in females and 0.72-0.82 mm in males), lateral fields with five incisures, labial probolae with well developed prongs, pharyngeal corpus 7-10 times isthmus length, ovary without flexures posterior to vulva, well developed, offset spermatheca, long post-uterine sac (85-109 µm), female tail subcylindrical,

2-3 anal body diam. long, male tail conoid 45-52 µm long, spicules 30-35µm long and gubernaculum about half of spicules length.

The new species resembles C. tenuis Rashid & Heyns, 1990, C. subtenuis

Rashid & Heyns, 1990 and C. magnus Rashid & Heyns, 1990 in general morphometrics, shape and body size. However, from C. tenuis it can be differentiated in the shape of labial probolae (prongs small and straight vs prongs long and curved towards each other), longer pharyngeal corpus in females (155-

177µm vs 105-150µm), longer female tail (42-49µm vs 25-40µm. From C. subtenuis it differs by slightly smaller pharynx in females (197-216µm vs 219-

240µm), males of C. subtenuis differs in having longer tail (45-52µm vs 38-

43µm), wider body diam. at cloaca (22-27µm vs 18-20µm), slightly larger c′ value (1.9-2.3 vs 1.6-1.8) and in the arrangement of genital papillae (three precloacal & five post-cloacal pairs vs four pre-cloacal & four post-cloacal pairs).

From C. magnus the new species differs by its smaller body size (753-829µm vs

883-1522µm), slightly posterior position of nerve ring and excretory pore (60-

66% & 60-72% vs 35-59% & 38-56% of the pharyngeal length respectively), smaller pharynx (197-216 µm vs 222-289 µm in females and 191-209 µm vs 211-

245 µm in males), relatively smaller spermatheca (35-47 µm vs 48-99 µm), smaller genital branch (73-113µm vs 143-218µm), smaller vulva-anus/tail ratio

(4.2-5.0 vs 5.2-8.0) and in having smaller testis (294-412µm vs 421-741µm).

Table 7: Measurements (in µm) of Chiloplacus aligarhensis sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 10) (n= 11) L 754 753-829 (786±28) 716-817 (772±33) a 23 23.1-28.9 (26.5±2) 23-31 (26.5±2.2) b 3.5 3.5-4.1 (3.8±0.2) 3.6-4.3 (3.9±0.2) c 15.7 15.7-18.5 (16.8±0.9) 14.4-16.5 (15.5±0.7) c´ 2.7 2-2.9 (2.5±0.3) 1.9-2.3 (2.1±0.1) V 67 65.5-68 (67±0.5) -- Maximum body width 32 26.5-38.5 (30.5±3.5) 25.5-35 (29.5±3) Lip width 10.5 10-11 (10.5±0.5) 10-11 (10.5±0.5) Lip height 7 7-8 (7.5±0.5) 7-8 (7.5±0.5) Length of stoma 11 11-12 (11.5±0.5) 10-12 (11±0.5) Corpus 169 155-177 (163±7) 148-165 (156±7) Isthmus 19 16.5-22 (18.5±1.5) 11.5-23.5 (17.5±3) Basal bulb length 24.5 22.5-26.5 (24±1) 22.5-25.5 (24±1) Pharynx 212.5 197-216 (205±6.5) 191-209 (198±7) Excretory pore from ant. end 127 124-145 (136±6.5) 127-143 (135±5) Nerve ring from ant. end 119 118-134 (127±5) 118-172 (140±20) Dierid from ant. end 142 140-165 (152±7.5) 141-155 (148±5) Basal bulb width 16.5 14.5-17.5 (16±1) 14-16.5 (15±1) Anterior sac (Spermatheca) 39 34.5-47 (39.5±4.5) -- Genital branch 98 73-113 (88.5±12) -- Post-uterine branch 106 85-109 (95±8) -- VBD 30 25-38 (30.5±3.5) -- Vulva- anus distance 204 201-234 (215±12) -- Rectum/cloaca 21.5 21.5-23.5 (23±1) 29.5-33.5 (31.5±1.5) Tail 48 42-49 (46.5±2.5) 45-52 (50±2) ABD 17.5 16.5-23.5 (19.5±2) 22-27 (24±2) Phasmids from anus 23.5 18.5-26 (23±2) -- Testis -- -- 294-412 (354±41) Spicules -- -- 30-35 (33.5±2) Gubernaculum -- -- 17-21 (19.5±1)

A B C

F G

E H

Fig. 13. Chiloplacus aligarhensis sp. n. A. Anterior region showing labial probolae, B. Anterior region showing stoma, C. Post-uterine sac, D. Uterus and spermatheca, E. Female posterior region, F. Male posterior region, G. Spicules and gubernaculum, H. Lateral lines (Scale bars = 20µm).

72 Genus Nothacrobeles Allen & Noffsinger, 1971

Diagnosis: Body length varying from 0.4 to 0.9 mm. Cuticle with broad annules, with or without longitudinal striae or punctations. Lateral fields with two to four incisures. Cephalic probolae in pairs, low, with or without serrate sculpture.

Labial probolae short to moderately long, slightly bifurcate and bordered with small tines; outer rim or shaft with basal ridge. Amphids minute. Pharyngeal corpus cylindrical. Female gonad cephaloboid. Tails in both sexes conical with acute tip. Phasmids anterior to the lateral caudal papilla in males.

Nothacrobeles punctatus sp. n.

(Fig. 14, 15)

Measurements: In Table 8.

Females: Body robust, slightly ventrally curved after fixation. Cuticle simple, transversely annulated, annuli 3-4 µm wide at midbody, with two rows of punctuations. Lateral fields about 1/6th of the body diam. at midbody. Incisures start about two stoma lengths from anterior end as two crenate lines and differentiate into four lines at the level of isthmus. Outer incisures crenate, inner ones smooth, areolation absent. Lateral fields extend up to the tail terminus.

Labial probolae 8-10 µm long, bifurcate for half their length, with a prominent dentate basal ridge protruding outwards towards the cephalic probolae. Prongs divergent and bifurcate, outer longer than the inner. Each prong with six triangular tines on inner margin and eight on outer margin. Primary and secondary axils deep with ‘U’ and ‘V’ shape respectively. Amphidial openings minute, oval or round in shape. Stoma cephaloboid. Cheilostom wide, with

almost triangular rhabdia. Gymnostom narrower than cheilostom and as wide as stegostom. Dorsal metarhabdion with a minute tooth. Pharyngeal corpus slightly fusiform 3.5-4.0 times isthmus length. Corpus-isthmus junction with transverse markings. Basal bulb spheroid, with well developed grinder. Nerve ring at 66-

78% of neck length, surrounding isthmus in anterior half. Excretory pore at the level or just posterior to nerve ring. Hemizonid about two annules posterior to excretory pore. Dierids in the isthmus region or at the level of basal bulb. Cardia conoid, 5-7µm long, surrounded by intestinal tissue. Intestine with distinct wide lumen throughout its length, intestinal cells well differentiated, rectangular in shape.

Reproductive system mono-prodelphic, ovary reversed, without any flexure. Oocytes arranged in a single row throughout. Oviduct short, tubular, made of eight differentiated cells. Spermatheca well developed, usually longer than the corresponding body diam., with few sperms. Uterus well developed, about two to three times body diam. long. Uterus differentiated into a proximal glandular part with narrow lumen and a swollen distal muscular part with wide lumen. Distal and proximal parts of uterus separated by slight constriction. Post- uterine sac less than one vulval body diam. in length. Vagina thick walled, about

1/3rd of vulval body diam. Vulva transverse, slit-like. Rectum slightly less than one anal body diam. long, with three rectal glands. Tail conical, 2-3 anal-body diam. long, with acute terminus. Phasmids located at less than one anal body diam. posterior to anus.

Males: General morphology similar to females. Posture slightly straighter than females but more ventrally curved posteriorly. Reproductive system monorchic,

testis reflexed ventrally, flexure on right side of intestine. Germinal zone with two to three rows of spermatogonia, leading to the maturation zone with spermatocytes and differentiated sperms at its distal end. Vas deferens with numerous small round sperms. Ejaculatory duct wider than vas deferens with narrow lumen. Tail conical, ventrally curved, terminating in an acute mucro.

Phasmids 1.3-1.5 anal body diam. posterior to anus. Genital papillae eight pairs; two pairs subventral precloacal, one pair subventral adcloacal and five pairs postcloacal. Of five postcloacal pairs, two pairs (one lateral and one subventral) are located just posterior to phasmid and three pairs (one subdorsal, one subventral and one lateral) near the tail tip. Spicules ventrally arcuate; manubrium rounded; calamus cylindrical; lamina swollen near calamus.

Gubernaculum well developed, slightly bent anteriorly.

Type habitat and locality: Soil sample collected from a potato field, Shahrekord,

Iran

Type specimens

Holotype female on slide Nothacrobeles punctatus sp. n./1, three females and six males (paratypes) on slides Nothacrobeles punctatus sp. n./1-4 deposited in the nematode collection of Department of Zoology, Aligarh Muslim

University, Aligarh.

Diagnosis and relationships

Nothacrobeles punctatus sp. n. is characterized by having two rows of punctations in each annule; bifurcate labial probolae, with divergent prongs; spermatheca 28-50 µm long; post-uterine sac less than one vulval body diam.

long; female tail conical with acute terminus; phasmids at 21-32% of tail length; spicules 45-49 µm long and gubernaculum 30-34 µm long.

The new species resembles Nothacrobeles subtilis Allen and Noffsinger,

1971 and N. maximus Allen and Noffsinger, 1971 in general morphometrics.

However, the new species differs from N. subtilis in cuticular punctations (with punctations vs without punctations), more anterior position of phasmid (21-32% vs near middle of tail) and in the presence of males. From N. maximus it can easily be differentiated by the structure of cuticle (without longitudinal striations vs with longitudinal striations), cuticular punctations (with punctations vs without punctations), lateral fields (incisures crenate anterior to dierids then smooth throughout the body length vs incisures crenate posterior to dierids) and in the presence of males (males absent in N. maximus).

Table 8: Measurements (in µm) of Nothacrobeles punctatus sp.n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n= 3) (n= 6) L 716 646-721 (683±35.0) 668-749 (710.5±28.0) a 18.5 16.3-18.7 (17.6±1.0) 18.2-19.5 (18.9±0.4) b 4.6 3.7-4.6 (4.2±0.3) 4.3-4.9 (4.6±0.2) c 10 10.0-11.5 (10.9±0.6) 10.7-12.6 (11.5±0.6) c’ 2.6 2.1-2.7 (2.5±0.3) 1.7-2.0 (1.9±0.1) V 63 62-63 (62.5±0.5) -- Maximum body width 39 39-40 (38.9±0.5) 35-40 (37.5±1.5) Lip width 17 15-17 (16.5±1.0) 16-17 (16.0±0.5) Lip height 15 14-15 (14.5±0.5) 13-14 (13.5±0.8) Length of stoma 13 10-18 (13.5±3.0) 13-15 (13.5±0.8)) Corpus 101 98-115 (105.0±6.5) 88-106 (99.5±6.0) Isthmus 28 25-31 (28.0±2.0) 25-31 (27.5±2.0) Basal bulb length 28 28-30 (28.5±1.0) 26-29 (27.5±1.2) Pharynx 155 149-171 (160.5±9.0) 138-163 (152.5±8.5) Excretory pore from ant. end 120 94-120 (110±10) 111-127 (118.5±5.0) Nerve ring from ant. end 109 109-134 (115±11) 106-112 (109.5±2.5) Dierid from ant. end 132.5 104-133 (123±11) 125-141 (132.5±5.0) Cardia 7 5-7 (6.0±0.8) 5-7 (6.5±0.8) Basal bulb width 21 21-22 (21.0±0.5) 20-22 (20.8±0.8) Anterior sac (Spermatheca) 49.5 27.5-49.5 (42±9) -- Genital branch 100 96-100 (98.0±1.5) -- Post uterine branch 26.5 24-27 (24.5±1.0) -- VBD 34 34-38 (35.5±1.5) -- Vulva- anus distance 194 182-202 (192±7) -- Rectum 23 22-24 (23±1) -- Tail 71 56.5-71.5 (63.5±6.5) 57-66 (62.0±3.0) ABD 26.5 24.5-26.5 (25.5±1.0) 30-34 (32.0±1.5) Phasmids from anus 21 12-22 (17.5±4.0) 22-25 (23.0±1.5) Testis -- -- 325-360 (341±12) Spicules -- -- 45-49 (46.5±1.5) Gubernaculum -- -- 30-32 (30.5±0.5)

A B D

G H I

Fig. 15. Nothacrobeles punctatus sp. n. A. Anterior region showing stoma, B&C. Labial probolae, D. Vulval region showing post-uterine sac, E. Glandular part of uterus and spermatheca, F. Cuticular punctations, G. Female posterior region, H. Spicules and gubernaculum, I. Lateral lines (Scale bars = 20µm).

79 Genus Stegellata Thorne, 1938

Diagnosis: Body 0.3-0.7 mm long. Cuticle with transverse as well as longitudinal striations, dividing each other to form small quadrate blocks. Lateral fields with three to five incisures. Cephalic probolae simple, low. Labial probolae tuning fork-shaped with thin shaft and U-like prongs. Pharyngeal corpus cylindrical.

Female genital organs cephaloboid. Female tail broadly, male tail narrowly rounded.

Stegellata ophioglossa Andrassy, 1967

(Fig. 16)

Measurements: In Table 9.

Females: Body small, straight to slightly ventrally curved after fixation. Cuticle with transverse and longitudinal striations, giving it a tessellated appearance.

Lateral fields distinct, occupying about 1/5th of the midbody diam.. Incisures three, outer ones crenate. Lip region with six separate lips having rounded margins. Labial probolae with wide base, 4-6µm long, bifurcate to about 1/3rd of their length. Prongs divergent and equal in size, forming a semicircular arc.

Amphidial apertures round. Stoma cephaloboid, cheilostom wide, with small ovoid rhabdia. Gymnostom narrower than cheilostom, and as wide as stegostom.

Metastegostom with a minute tooth like projection on dorsal rhabdia. Pharyngeal corpus cylindrical, with distinct lumen, 3.3-4.5 times isthmus length. Corpus- isthmus junction distinctly demarcated. Basal bulb ovoid or pear-shaped with well a developed grinder. Nerve ring surrounding the base of corpus at 60-67% of neck length. Excretory pore opposite the trailing end of nerve ring or at 62-71%

of neck length. Hemizonid just posterior to the excretory pore. Dierids at about

65-71% of neck length, lying in the anterior half of isthmus. Cardia short, conoid, surrounded by intestinal tissue. Intestine with wide lumen at its anterior region.

Reproductive system mono-prodelphic. Ovary posteriorly directed without any flexure. Oocytes arranged in two rows in the germinal zone and in a single row in the proliferative zone. Oviduct short, tubular. Spermatheca less than the corresponding body diam long, without sperms. Uterus simple, tube like, undifferentiated. Post-uterine sac less than one vulval body diam. long. Vagina, thick walled, with sclerotization. Vulva transverse, slit like. Rectum 1.2-1.6 anal body diam. long. Tail cylindrical, 2.6-3.5 anal body diam. long, with approximately 20 ventral annuli. Tail terminus flat. Phasmids one anal body diam. posterior to anus.

Males: Not found.

Habitat and locality: Soil sample collected from the root zone of Sorghum sp. from village Nohati, Madrak and from the root zone of Trifolium alexandrinum from village Pisava, Chandaus, Aligarh.

Voucher specimens

17 females on slides Stegellata ophioglossa (N)/1-9 and 12 females on slides Stegellata ophioglossa (P)/1-4 deposited in the nematode collection of

Department of Zoology, Aligarh Muslim University, Aligarh.

Remarks

S. ophioglossa is a terrestrial nematode, this species have previously been recovered from sandy soils and dune sands. It is widely distributed and has been described from Europe (Hungary, Italy), Asia (Uzbekistan, Mongolia), Africa

(Senegal) and South America (Venezuela). This is the first report of S. ophioglossa from India, where, it was recovered from sandy as well as from loamy soil. Despite the change in type of habitat the measurements and descriptions of our specimens agree well with that of Stegellata ophioglossa

Andrassy, 1967. However slight variations from the original description were observed in the height of labial probolae (4-6 µm vs 8-11 µm), relatively smaller pharynx (96-112 µm vs 110-130 µm), smaller post-vulval uterine sac (less than corresponding body diam. vs as long as or longer than corresponding body diam.)

Table 9: Measurements (in µm) of Stegellata ophioglossa Andrassy, 1967 Mean and S.D. given in parenthesis

Females (n= 10) Females (n=12) Characters Nohati population Pisava population L 327 – 386 (347 ± 16) 341 – 409 (347 ± 16) a 18.3 – 23 (21 ± 1.5) 19.2 – 22 (20.2 ± 0.8) b 3.1 – 3.7 (3.4 ± 0.2) 3.2 – 3.7 (3.4 ± 0.2) c 10.3 – 11.9 (11.1 ± 0.5) 10 – 11.4 (10.6 ± 0.5) c’ 2.6 – 3.4 (3 ± 0.2) 2.9 – 3.7 (3.1 ± 0.2) V 62 – 64.5 (63 ± 0.5) 61 – 63.5 (62 ± 0.5) Maximum body width 15 – 18 (16.5 ± 1) 15.5 – 20 (18 ± 1) Lip width 6 – 7 (6 ± 0.3) 6 – 7 (6.9 ± 0.3) Length of stoma 9.0 9.0 – 10 (9.5 ± 0.5) Corpus 66.5 – 72.5 (70 ± 2) 69.5 – 77 (72 ± 2) Isthmus 14.5 – 21.5 (18 ± 1.5) 18.5 – 24.5 (22 ± 1.5) Basal bulb length 14 – 16 (14.5± 0.5) 13 – 17 (14.5± 1) Pharynx 96 – 112 (102.5 ± 4.5) 104 – 114 (108 ± 3) Excretory pore from ant. end 67.5 – 73.5 (69 ± 1.5) 69.5 – 75 (73 ± 1.5) Nerve ring from ant. end 61.5 – 68.5 (65.5 ± 2.5) 68 – 73 (70.5 ± 1.5) Dierid from ant. end 72.5 – 79 (74.5 ± 2.5) 75 – 82 (78.5 ± 2) Basal bulb width 9 – 12 (10 ± 0.5) 10 – 13 (11 ± 0.5) Anterior sac (Spermatheca) 10 – 14 (12 ± 1.5) 7 – 10 (9 ± 1) Genital branch 36.5 – 65.5 (45.5 ± 7.5) 32.5 – 48.5 (40 ± 4) Post uterine branch 8 – 12 (10 ± 1.2) 8 – 11 (10 ± 1) VBD 14 – 17 (15.5 ± 1) 15 – 19 (17 ± 1) Vulva- anus distance 89 – 113 (98 ± 6.5) 92 – 119 (105 ± 7) Rectum 13 – 15 (14 ± 0.5) 14 – 16 (15 ± 0.5) Tail 28.5 –34.5 (31 ± 1.5) 30.5 –37.5 (35 ± 2) ABD 9 – 12 (10.5 ± 1) 10 – 12 (11 ± 0.5) Phasmids from anus 9 – 10 (9.5 ± 0.5) 7 – 15 (10.5 ± 2)

Genus Zeldia Thorne, 1937

Diagnosis: Body length between 0.6-1.0 mm. Cuticle annulated, annuli with or without punctations or tessellation. Lateral fields with three to five incisures, outer lines sometimes crenate. Lateral fields with or without areolations. Cephalic probolae triangular, flap-like, low with setose projections. Labial probolae low and rounded to elongate and shallowly to deeply bifurcate at one level; without tines. Amphidial apertures elongate-oval. Lining of cheilostom without or with 1-

3 tooth-like processes. Pharyngeal corpus long and cylindrical. Intestine often with prerectum. Postvulval uterine branch short or absent. Tails in both sexes conoid, with pointed or finely rounded tip. Males rare or unknown in most species.

Zeldia tridentata Allen and Noffsinger, 1972

(Fig.19, 20)

Measurements: In Table 10.

Females: Body robust, gradually tapering toward both the ends, straight or slightly curved ventrally. Cuticle with transverse annules, 1.6 – 2 µm wide at the pharynx base and midbody and 1.6 - 1.8 µm wide at tail. Each annule with two rows of punctations. Lateral fields with three lines, outer ones crenate, areolated in the pharyngeal region. Lip region 10-11 µm wide, 4-5µm high. Labial probolae low, with round margins and shallow grooves. Primary axils deep, with dentate guard processes. Amphidial apertures oval. Cheilostom with prominent cylindrical walls, each cheilorhabdion associated with a structure having three teeth. Gymnostom longer than cheilostom, metastegostom with a small tooth like

process on dorsal wall. Pharyngeal corpus cylindrical, 7.9-9.2 times isthmus length. Isthmus shorter than basal bulb. Basal bulb ovoid, 21-26 x 18-21 µm, with a grinder at its middle or slightly anterior. Cardia conoid, surrounded by intestinal tissue. Intestine with wide lumen. Nerve ring at 59-66% of neck length, surrounding the distal part of the corpus. Excretory pore just posterior to nerve ring or one to two annules anterior to hemizonid. Deirids in the posterior region of corpus, or at 67-78 % of neck length.

Reproductive system mono-prodelphic, ovary reversed, on right side of intestine, with or without additional flexures posterior to vulva. Oocytes usually arranged in a single row throughout the ovary length. Spermatheca scarcely developed. Oviduct short. Uterus tubular, without any differentiation. Post- uterine sac short, 0.3-0.5 times vulval body diam. long. Vagina with thick walls, slightly anteriorly directed. Rectum 21-28 µm long. Tail elongate conoid, 4-5 anal body diam. long, with acute terminus. Phasmids 1-3 µm posterior to anus.

Male: Not found

Habitat and locality

Soil sample collected from an orchard of guava and cashew-nut near

Chilika lake, Puri, Orissa.

Voucher specimens

9 females on slides Zeldia tridentata/1-2 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University, Aligarh.

Remarks

Z. tridentata is distinguished from other species of the genus by the presence of three teeth associated with each cheilorhabdion and the longer tail.

This species is widely distributed throughout the world and has been collected from India, Jamaica, Philippine Islands, Srilanka, Taiwan, Thailand, and

Venezuela. Most of the species of the genus were collected from the soil or sand around the root zone of different plants. The present population was also collected from the sandy soil, around the root zone of Guava and Cashew Nut plantations.

The measurements and descriptions of our specimens agree well with that of Zeldia tridentata Allen & Noffsinger, 1972. However differences from original population were found in the lateral fields (outer incisures crenated vs smooth). Rashid et al., 1984, collected two females of this species from Itapebi,

Lombardia, Brazil, (Host: Theobroma cacao). They Illustrate and redescribed the species and added more details to the original description. In Brazilian population, cuticular punctations were not observed, however the punctations have been reported in the original descriptions and are distinctly visible in our population also. They also mentioned the ovary with a double flexure posterior to vulva but in our population the specimens without any flexure were also found along with the specimens having double flexure. In Brazilian population the phasmid lies at about 5-6 annules posterior to anus however, in our population phasmid lies just posterior to anus.

Table 10: Measurements (in µm) of Zeldia tridentata Allen and Noffsinger, 1972 Mean and S.D. given in parenthesis

Characters Females (n= 9) L 635-779 (724±46) a 19.0-23.5 (20.8±1.3) b 3.7-4.0 (3.9±0.1) c 8.5-9.0 (8.8±0.2) c’ 4.1-4.9 (4.5±0.3) V 61-62 (61.5±0.3) Maximum body width 30.5-40.5 (35±3.0) Lip width 10-11 (11±0.5) Lip height 4-5 (4.5±0.5) Length of stoma 15-17 (15.5±0.5) Corpus 135.5-155.5 (147±6.5) Isthmus 14-19 (16.5±1.5) Basal bulb length 20-25.5 (23.5±1.5) Pharynx 170-200 (187±9.0) Excretory pore from ant. end 109-126.5 (121±5.5) Nerve ring from ant. end 105-121.5 (116.5±5.5) Dierid from ant. end 124-149 (137.5±9.0) Cardia 5-6 (5±0.5) Basal bulb width 18-21 (19±1) Anterior sac (Spermatheca) 7-14 (10.5±2.5) Genital branch 70-135 (9±21) Post uterine branch 12-18 (13.5±2.0) VBD 31.5-40.5 (35.5±3.5) Vulva- anus distance 166-209 (194±14) Rectum 21-28 (24.5±2.0) Tail 73-87 (82.5±4.0) ABD 16-21 (17.5±1.5) Phasmids from anus 1-3 (2±0.7)

Superfamily Panagrolaimoidea Thorne, 1937

Diagnosis: Buccal cavity a single, fairly wide chamber, sometimes tending to taper at its base. Metastom anisoglottoid and anisomorphic, narrower than anterior part; telostom small and narrow. Pro-, meso- and telorhabdions usually conspicuously thickened; cheilorhabdions sometimes thickened; metarhabdions not thickened but metastom segments often bearing small teeth. Pharyngeal corpus cylindrical or with swollen valveless median bulb; a narrow isthmus and a basal bulb with grinders. Female genital organ prodelphic, ovary reflexed once, usually well down into body; a short post-vulval sac sometimes present. Tip of male gonad usually reflexed. Male supplements papilloid, arranged in pairs. No bursa. Phasmids well discernible.

Type family: Panagrolaimidae Thorne, 1937

Other subfamilies: Alirhabditidae Suryawanshi, 1971

Brevibuccidae Paramonov, 1956

Family Panagrolaimidae Thorne, 1937

Diagnosis: Cuticle annulated, lateral fields distinct. Lip region practically without probolae. Lips three or six, moderately developed.Amphids located on lateral lips, small. Stoma consisting of the usual six elements, its anterior section

(cheilo- and gymnostom) spacious, stegostom tapering, metastom with a small tooth-like projection. Pharynx consisting of corpus, isthmus and bulb. Female genital organ prodelphic, reflexed part extending far behind vulva, rarely with a simple flexure. Anterior separated portion of uterus serving as a spermatheca.

Postvulval uterine sac present. Males mostly abundant. Preanal genital papillae in

5-7 pairs. Tail conoid or elongate, in male generally shorter than in female.

Phasmids always distinct.

Type subfamily: Panagrolaiminae Thorne, 1937

Other subfamilies: Panagrellinae Andrassy, 1976

Tricephalobinae Andrassy, 1976

Turbatricinae Goodey, 1943

Baujardiinae Andrassy, 2005

Subfamily Tricephalobinae Andrassy, 1976

Diagnosis: Cuticle finely annulated, lateral fields distinct. Lip region without probolae. Lips three or six, moderately developed. Cheliostom small and less sclerotized, gymnostom well developed, stegostom tapering, Pharyngeal corpus with bulb like median swelling. Terminal bulb very strong. Female genital organ panagrolaimoid. Postvulval uterine sac present. Males mostly abundant. Genital papillae 6-7 pairs. Tail uniformly conoid in female. Phasmids always distinct.

Type genus: Tricephalobus Steiner, 1936

Other genus: Halicephalobus timm, 1956

Genus Tricephalobus Steiner, 1936

Diagnosis: Body length between 0.5-1.0 mm. cuticle finely annulated, lateral fields narrow. Head broad, continuous with body, lips three, separate. Cheilostom short and not sclerotized, gymnostom well developed, stegostom funnel- shaped.

Pharyngeal corpus posteriorly swollen, bulb-like. Terminal bulb very strong.

Female genital organ panagrolaimoid, postvulval branch present. Both sexes

equally common. Spicules with narrowed proximal end, gubernaculum thin.

Genital papillae six or seven pairs. Tail conoid in female, and strongly narrowed at posterior half in male, terminus sharp.

Tricephalobus quadripapilli sp.n.

(Fig.18, 19)

Measurements: In Table 11.

Females: Body slender, slightly ventrally curved after fixation. Cuticle simple, with fine transverse annulations. Lateral fields narrow with two incisures, occupying about 1/9th of the body diam. at midbody. Incisures arise at level of median bulb as two smooth lines and extend up to the level of phasmids. Labial probolae absent. Lips three, low and rounded, continuous with body contour.

Amphids indistinct. Stoma tubular, cheilostom with indistinct rhabdia.

Gymnostom slender, tube like, surrounded by a granular band like structure.

Stegostom as long as gymnostom, with slightly tapering dorsal wall. Pharyngeal corpus posteriorly swollen into an oval median bulb, 2.7 – 3.7 times isthmus length. Isthmus tubular. Basal bulb pyriform, with well developed grinder. Nerve ring at 67-73% of neck length, surrounding isthmus at its middle. Excretory pore at level of basal bulb. Dierids situated at the level of basal bulb or slightly posterior to pharynx. Cardia short, conoid, surrounded by intestinal tissue.

Intestine with distinct wide lumen.

Reproductive system mono-prodelphic. Ovary reversed, without any flexure, extending upto anus level. Oocytes arranged in multiple rows in germinal zone and in a single row in maturation zone. Oviduct short, tubular, separated

from spermatheca by constriction. Spermatheca in continuation of uterus, separated from it by slight constriction. Uterus well developed, differentiated into a proximal glandular part and a distal muscular part with distinct lumen. Distal part is twice as long as muscular part, both parts were separated by a constriction.

Post-uterine sac continuous with uterus, small, less than half vulval body diam. in length. Vagina slightly anteriorly directed, about 1/3 - 1/2 of vulval body diam. in depth. Vulva transverse, slit-like. Vulval lips slightly protruded. Rectum about one anal body diam. long. Tail conical, 2.6-3.7 anal-body diam. long, with narrowly rounded terminus. Phasmids 1.3-1.8 anal body diam. posterior to anus.

Males: Body slightly smaller than females. General morphology similar to that of females. Reproductive system monarchic. Testis reflexed ventrally, flexure on right side of intestine. Germinal zone with two to three rows of spermatogonia, leading to the maturation zone with spermatocytes. Tail conical, ventrally curved, strongly narrowed in its posterior half, terminating in a rounded tip. Phasmids indistinct. Genital papillae four pairs; one subventral pair precloacal, situated at level of spicule head, three pairs postcloacal. Of three postcloacal pairs, one subventral pair is located at less than one anal body diam. posterior to cloacal opening. Two pairs (one subventral and one subdorsal) located just anterior to the beginning of narrower part of the tail. Spicules broad, with rounded manubrium, broad calamus, ventrally arcuate lamina, with two longitudinal incisures from the calamus. Spicule tip rounded. Gubernaculum small, less then half of spicules length.

Type habitat and locality: Farm yard manure collected from a fallow field,

Poonch Jammu & Kashmir, India.

Type specimens

Holotype female on slide Tricephalobus quadripapilli sp. n./1; nine females and ten males (paratypes) on slides Tricephalobus quadripapilli sp. n./2-

6, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Tricephalobus quadripapilli sp. n. is characterized by very fine transverse annulations, a granular band around the gymnostom region, lateral fields with two incisures, a well developed median bulb, ovary extending upto rectum region, a constriction between glandular and muscular parts of uterus, sett off spermatheca, broad spicules about 18-24 µm long, genital papillae four pairs and tail with narrowed posterior half region.

The new species closely resembles T. steineri (Andrassy, 1952), Rühm,

1956 in general morphology and morphometrics. However, it can be differentiated from T. steineri in having smaller post-uterine sac (less than half vs one corresponding body diam. long), smaller tail (2.6-3.7 vs 4 ABD long in females and 2.2-2.5 vs 3.5 ABD long in males), number of precloacal genital papillae (one vs three).

Table 11: Measurements (in um) of Tricephalobus quadripapillii sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n=9) (n=10) L 491 434-517 (476±29) 391-473 (439±29) a 17.7 17.5-19 (18.3±0.5) 18-20.5 (19.5±0.8) b 5.3 4.6-5.8 (5.1±0.3) 4.2-5.1 (4.7±0.3) c 10.8 9.7-12.8 (10.9±1.0) 10.5-12.5 (11.3±0.6) c’ 3.1 2.6-3.7 (3.1±0.3) 2.2-2.5 (2.4±0.09) V 61 58.5-62.5 (61±1.0) -- Maximum body width 27.5 23-29 (26±2.0) 20-25 (22.5±1.5) Lip width 7 7-8 (7.3±0.5) 6-7 (6.7±0.4) Length of Stoma 11 9-11 (10±0.5) 9-10 (9.2±0.5) Corpus 56.5 54.5-59.5 (56.5±2) 49.5-60.5 (54.5±3.5) Isthmus 19 16-22 (19±1.5) 17-29 (22.5±4) Median bulb width 12 11-13 (12±0.5) 10-11 (10.5±0.5) Basal bulb length 18 17-20 (18.5 ±1.0) 17-21 (18±1) Basal bulb width 15 13-15 (14±0.5) 11-14 (12.5±1) Pharynx 93 89-99 (94±2.5) 83-107 (94±7) Excretory pore from anterior end 90 80-91 (85±4) 73.5-89 (81±5.5) Nerve ring 67.5 63.5-69.5 (66.5±2) 57.5-74 (66±5) Genital branch 113 90-127 (109±11.5) -- VBD 28 22.5-28.5 (26.5±1.5) -- Vulva- anus distance 144.5 122-164 (142±13) -- Rectum/cloaca 16 13-17 (15±1) 14-18 (16±1.5) Tail 45.5 38.5-49.5 (44±3) 35.5-43.5(39±2.5) ABD 15 12-15 (14±1) 15-18 (16.5±1) Phasmids from anus 22 20-25 (22±1.5) -- Testis -- -- 196-261 (230±26) Spicules -- -- 18-25 (21±2) Gubernaculum -- -- 7-10 (8.5±1)

A B E

D F

H G I

Fig. 19. Tricephalobus quadripapilli sp. n. A. Pharyngeal region, B. Anterior region showing stoma, C. Anterior region showing granular band around gymnstom, D. Lateral lines, E. Vulval region showing post-uterine sac, F. Female reproductive tract showing uterus, G. Female posterior region, H. Spicules and gubernaculum, I. Male posterior region (Scale bars = 20µm).

97 Family Brevibuccidae Paramonov, 1956

Diagnosis: Lips six, stoma relatively small, nearly twice as long as wide.

Pharyngeal corpus cylindrical or posteriorly swollen into a strong terminal bulb.

Female genital organ panagrolaimoid. Reflexed part of ovary not reaching to vulva. Post-vulval uterine sac absent.

Type and only subfamily: Brevibuccinnae Paramonov, 1956.

Subfamily Brevibuccinae Paramonov, 1956

Diagnosis: Lips six, stoma relatively small, nearly twice as long as wide or smaller or equal to lip region width. Pharyngeal corpus cylindrical or posteriorly swollen. Reflexed part of ovary not reaching to vulva. Post-vulval uterine sac absent. Both arms of spicules are equal or unequal, species often with unusually long spicules.

Type genus: Brevibucca Goodey, 1935

Other genera: Cuticonema Sanwal, 1959

Plectonchus Fuchs, 1930

Genus Brevibucca Goodey, 1935

Diagnosis: Stoma short, expanding slightly at base, cheilostom and gymnostom thick walled, forming half stoma depth; stegostom with an inwardly projecting short tooth. No pharyngeal collar. Pharyngeal corpus cylindrical, isthmus short, terminal bulb with grinder. Vulva posterior, gonad mono-prodelphic. Ovary

reversed not reaching vulval opening. A uninucleate gland cell on each side of the uterus close to vagina. Testis outstretched. Spicules paired but of unequal size. Gubernaculum present. Bursa absent. Genital papillae eight pairs.

Brevibucca postamphidia sp. n.

(Fig. 20, 21)

Measurements: In Table 12.

Females: Body slender, slightly arcuate upon fixation, tapering towards both ends. Cuticle with fine transverse and longitudinal striations. Punctations fine, sub-cuticular, transversely arranged. Lips separate, with minute hair like papillae.

Amphidial openings large, oval, post-labial at about 1/3rd of stoma length from anterior end. Amphidial canal and fovea prominent. Cheilostom well developed, slightly longer than wide, with thick cuticularised walls. Gymnostom short and cuticularised. Stegostom anisomorphic. Dorsal wall provided with a tooth, each subventrals with a smaller tooth. Pharyngeal corpus cylindrical, muscular, about

2.5 times isthmus length. Corpus isthmus junction distinct. Isthmus tubular. Basal bulb ovoid, with well developed grinder and single haustrulum. Excretory pore at level of corpus region, at about 38-43% of the pharyngeal length. Paired excretory cells present just above basal bulb. Nerve ring encircling isthmus just below corpus-isthmus junction, approximately at 62-66% of pharyngeal length.

Pharyngo-intestinal junction with well developed cardia consisting of three flaps.

Intestinal cells large, granular. Intestinal lumen variable in width.

Female reproductive system mono-prodelphic, ovary reflexed. Oviduct narrow, joining ovary at a point slightly posterior to anterior tip. Spermatheca set off by a slight dilation. Uterus undifferentiated, filled with embryonated eggs and /or sperms. Up to ten eggs may be present at a time in the uterus. Vagina strongly muscular, vaginal lumen unusually curved. Vulva a small transverse slit, situated about 2.5 anal body diam. anterior to the anus. A uninucleate gland cell on each side of the uterus close to vagina, connected by a duct to the uterus.

Post-uterine sac absent. Rectum 1.5-1.9 anal body diam. long, usually with wide lumen. Tail extremely long filiform, 11-24 anal body diam., with fine tip.

Phasmidial openings distinct, 2-3 anal body diam. posterior to anus. Phasmidial glands extending to just below the rectum.

Males: Body smaller than females, strongly curved ventrally in the posterior region. Anterior end similar to that of females. Testis single, straight, outstretched. Spicules dissimilar and of unequal size, larger one 27-30µm long and smaller one 20-22μm long. Gubernaculum about half of larger spicule in length, slightly curved proximally and with a sleeve distally. Genital papillae eight pairs; three pre-cloacal (two subventrals and one lateral adcloacal), five post-cloacal pairs. Of five postcloacal pairs, one subventral pair is located just posterior to cloacal opening while three subventrals and one subdorsal pair are closely grouped. This group is present just beyond phasmid, at the end of conoid part of tail. Male tail with conoid part and a long filiform part.

Type habitat and locality: Decaying banana rhizome collected from Haldwani,

Uttarakhand.

100

Type specimens

Holotype female on slide Brevibucca postamphidia sp. n./1; twenty one females and twelve males (paratypes) on slides Brevibucca postamphidia sp. n./2-14, deposited in the nematode collection of Department of Zoology, Aligarh

Muslim University, Aligarh.

Diagnosis and relationship

Brevibucca postamphidia sp. n. is characterized by post-labial amphids and large amphidial openings. Pharyngeal corpus about 2.5 times isthmus length.

Strongly muscular vagina with unusually curved vaginal lumen. Vulval slit about

2.5 anal body diam. to anus. A uninucleate gland cell on either side of uterus.

Long filiform female tail, about 11-24 anal body diam. in length (c=2.6-3.9).

Males with unequal and dissimilar spicules and eight genital papillae.

The new species closely resembles Brevibucca punctata Timm, 1960 in general morphology and morphometric values in females but differs from it in having smaller ‘c’ value in males (5.9-7.7 vs 8-10), structure of testis (outstreched vs reflexed), size of gubernaculum (12-13 µm vs 18-22 µm) and in the position of genital papillae (subdorsal pair anterior or almost at level of subventral group vs subdorsal pair located posterior to subventral group).

101

Table 12: Measurements (in um) of Brevibucca postamphidia sp. n. Mean and S.D. given in parenthesis

Characters Holotype Paratype females Paratype males female (n=21) (n=12) L 1446 1065-1679 (1380±199) 714-828 (766±35) a 36.5 28.5-43.0 (35±4.5) 25-30 (27±1.5) b 6.0 4.5-6.1(5.5±0.6) 3.9-4.2 (4±0.1) c 3.2 2.6-3.9 (3.1±0.5) 5.9-7.7 (6.9±0.6) L` 988 795-1073 (953±271) -- a’ 24.9 22.1-34.6 (24.8±27.6) -- b’ 4.2 3.2-4.4 (3.8±1.1) -- c′ 20.1 14.5-25.5 (20±2.8) 4.6-6.2 (5.5±0.5) V 64 58-70 (63±3.5) -- Maximum body width 39.5 34.5-49.5 (39.5±4.5) 26-32.5 (28.5±2.0) Lip width 12.8 11-13 (12.5±0.5) 10-11 (10.0±0.3) Lip height 5 5-6 (5.1±0.4) 4-5 (4.2±0.4) Stoma length 18 17-19 (18±0.5) 14-15 (14.5±0.5) Stoma width 7 5-8 (5.5±1.5) 5-6 (5.2±0.4) Corpus 148 146-173 (157±9.5) 107-122 (115±4.5) Isthmus 60.5 57.5-74.5 (63±4.5) 47.5-55.5 (50±2) Basal bulb length 28.5 26.5-32.5 (29.5 ±1.5) 23-26 (24.5±1.0) Basal bulb width 22.5 21-28 (23±2) 17-18 (17.5±0.5) pharynx 237.5 231-276 (249±14.5) 177-203 (189.5±6.5) Excretory pore from anterior end 97 89-112 (99±7) 75-88 (81.5±4.0) Nerve ring 148.5 148-179 (161±11) 113-129 (121±5) Anal body diameter(ABD) 22.5 19-26 (22.5±2.0) 18-22 (20.5±1.0) Genital branch 401 287-612 (412±95) -- Vulval body diameter (VBD) 32 26.5-37.5 (31.5±3.0) -- Vulval anus distance 63 44.5-63.5 (55±5.5) -- Testis -- -- 312-409 (342±26.5) Rectum 43.5 33-44 (38.5±3.6) -- Tail 458 274-626 (452±94) 101-124 (112±8.0) Phasmids from anus 59 47.5-64.5 (56-5.0) 25-30 (27±2.5) Spicule (Small) -- -- 20-22 (20.5±0.8) Spicule (Large) -- -- 26.5-29.5 (28.5±1) Gubernaculum -- -- 12-13 (13±0.5)

102

A B C D

E F K L

G H I J

Fig. 21. Brevibucca postamphidia sp. n. A-C. Anterior region showing parts of stoma, D. Anterior region showing amphid, E. Excretory cell, F. Part of gonad showing junction between oviduct and ovary, G. Female posterior region showing phasmid, H. Rectum, I. Female posterior region showing bivulvate condition, J. Anal opening, K, Anterior part of testes, L&M. Male posterior region showing spicules and gubernaculum

104 Genus Plectonchus Fuchs, 1930

Diagnosis: Body slightly curved ventrally when heat-killed. Cuticle with delicate annulations and fine transverse striae. Lateral fields with two ridges. Lip region with six low lips slightly separated. Amphids circular. Stoma with a wide and short cheilostom and gymnostom. Corpus cylindrical, without a distinction between pro- and metacarpus. Isthmus long and narrow. Basal bulb rounded or pyriform with distinct grinders. Nerve ring encircling the isthmus. Female reproductive system monodelphic-prodelphic.

Plectonchus coptaxii sp. n.

(Fig. 22, 23)

Measurements: In Table 13.

Females: Body slender, straight to slightly ventrally curved after fixation, tapering abruptly and curved strongly beyond vulva. Cuticle 2-3 µm thick, hyaline, with very fine transverse striations. Lateral fields indistinct. Lips round with short hair-like papillae. Amphidial apertures oval, post-labial in position.

Stoma very shallow, rhabdions fused and poorly developed, without any armature. Pharynx panagrolaimoid. Pharyngeal corpus cylindrical, longer than the combined length of isthmus and basal bulb. Corpus-isthmus junction very gradual sometimes indistinct. Isthmus tubular, 0.45-0.6 times corpus length.

Basal bulb pyriform, with distinct grinder. Nerve ring encircling isthmus in its anterior half, at 58-66% of the neck length. Excretory pore in the corpus region, at 43-47 % of neck length. Dierids and hemizonid indistinct. Cardia conoid, surrounded by intestinal tissue. Intestine with wide lumen.

105

Reproductive system monodelphic-prodelphic. Ovary on right side of intestine, reversed, without flexure, never extending beyond vulva. Oocytes arranged in two rows in the germinal zone and in single row in the maturation zone. Oviduct short. Spermatheca small, less than the corresponding body diam. in length, slightly offset and without sperms. Uterus tubular differentiated into a proximal and a distal part with thin walls and distinct lumen. The lumen of distal part usually filled with a single row of granular structures. Vagina short, anteriorly directed. Vulval lips depressed to form a sunken vulva. Post-uterine branch absent. A ventral body pore is present slightly posterior to vulva. Rectum straight, 1.1-1.3 anal body diam. long. Tail elongate conoid, 3.1-4.2 anal body diam. long, terminus pointed. Phasmids about one anal body diam. posterior to anus, at 27-35% of tail length.

Males: Anterior end similar to that of females, habitus ventrally curved, more in the posterior region. Cuticle thick and hyaline like that of females. Testis reflexed ventrally, on right side of intestine. Spicules dissimilar, unequal and separate.

Right spicule slightly longer than left, straight, slender, with a bifid tip. Left spicule more robust, arcuate, with fusiform lamina and without a bifid tip.

Gubernaculum heavily sclerotized, more than half of spicule length, strongly curved at its distal end. Genital papillae eight pairs. Two subventral pairs precloacal and six pairs postcloacal. Of six postcloacal pairs, two pairs (one subventral and one lateral) are anterior to phasmid. Two subdorsal pairs and two subventral pairs are located posterior to phasmid. Tail conoid with acute terminus.

106

Type habitat and locality: Organic manure collected from an agricultural field,

Mendhar, Jammu and Kashmir, India.

Type specimens

Holotype female on slide Plectonchus coptaxii sp. n./1; nine females and eight males (paratypes) on slides Plectonchus coptaxii sp. n./2-5 deposited in the nematode collection of Department of Zoology, Aligarh Muslim University,

Aligarh.

Diagnosis and relationship

Plectonchus coptaxii sp. n. is characterized by a slender body; thick cuticle with hyaline portion and fine transverse striations. Lips with hair like papillae. Amphids oval, post labial in position. Stoma shallow without any armature, rabdions fused. Ovary reversed, without flexure. Distal part of uterus with a single row of granular structures. Ventral body pore posterior to vulva.

Female tail elongate conoid, with narrowly rounded terminus. Male tail conoid, with acute terminus. Spicules symmetric or asymmetric. Gubernaculum strongly sclerotized, more than half spicule length. Genital papillae eight pairs.

The new species closely resembles P. molgos Massey, 1974 but can be differentiated by the structure of cuticle (with transverse striae vs without transverse striae), larger ‘a’ value in females (24.5-31.9 vs 20.4-24.4), smaller ‘b’ value (4.0-4.4 vs 5.1-5.6 in females and 3.9-4.1 vs 4.2-4.9 in males), more posteriorly located vulva (V= 78-81% vs V=75%), shape of vulval lips

(depressed vs protuberant), tail shape (without constriction vs constricted) and number and arrangement of genital papillae (eight pairs vs six pairs).

107

P. coptaxii sp. n. differs from P. wyganti Massey, 1964, in having smaller body (485-585 µm vs 700 µm in females and 472-517 µm vs 600 µm in males), smaller ‘b’ value (4.0-4.4 vs 4.5 in females and 3.9-4.2 vs 4.6 in males), greater

‘c’ value in males (12-13 vs 10.8), number and arrangement of genital papillae

(eight pairs vs seven pairs).

108

Table 13: Measurements (in µm) of Plectonchus coptaxii sp. n. Mean and S.D. given in parenthesis

Holotype Paratype females Paratype males Characters female (n=9) (n=8) L 530 485-585(536±27.5) 472-517 (495±16) a 28.2 24.5-31.9 (27.7±2.4) 24.4-32.6 (27.4±2.4) b 4.1 4.0-4.35 (4.2±0.11) 3.9-4.2 (4±0.1) c 11.9 9.8-13.0 (11.7±0.9) 12-13 (12.4±0.4) c’ 3.5 3.1-4.2 (3.5±0.5) 2.1-2.7 (2.3±0.2) V 79 78-81 (79.5±1.0) -- Maximum body width 19 18-21 (19.5±1.0) 16-21 (18±1.5) Lip width 6.93 6.93 6.93 Length of Stoma 4 4-5 (4.5±0.5) 3-5 (3.5±0.5) Corpus 70 64.5-77.5 (72±3.5) 61-71 (68±3) Isthmus 40.5 31.5-43.5 (38±4) 34.5-46.5 (38.5±3.5) Basal bulb length 17 16-19 (17.5 ±1.0) 16-17 (16.5±0.5) Basal bulb width 11 11-12 (11.5±0.5) 9.8 Pharynx 127.5 113-137.5 (128±7) 121-126 (123±1.5) Excretory pore from anterior end 55.5 54.5-64.5 (58.5±3) 49.5-57.5 (52±2.5) Nerve ring from anterior end 74 72-88 (81±5) 70-77 (75.5±2.5) Anterior sac (Spermatheca) 13 12-14 (13±1) -- Genital branch 201 185-248 (212±22) -- VBD 17 15-20 (17±1.5) -- Vulva – anus distance 66 56.5-74 (63.5±5.5) -- Rectum/cloaca 15 15-16 (15.2±0.5) 15-19 (17±1.5) Tail 45 39.5-54.5 (46±4) 26-42.5 (38±5) ABD 13 12-14 (13±0.5) 16.5-21 (17±1) Phasmids from anus 15 14-16 (14.5±1.0) -- Testis -- -- 245-312 (280±24) Spicules -- -- 19-21 (20±0.5) Gubernaculum -- -- 12-16 (14±1.5)

109

A B C D

H F

Fig. 23. Plectonchus coptaxii sp. n. A. Pharyngeal region, B&C. Anterior region showing stoma, D. Anterior region showing amphidial aperture (dorsoventral), E. Female genital tract showing part of uterus, F. Female posterior region showing vulva and anus, G. Male posterior region showing spicules, H. Male posterior region showing gubernaculum (Scale bars = 20µm).

111

Summary

The present work represents a taxonomic study of the nematodes of suborder

Cephalobina. Samples of soil and organic manure were collected from various parts of the country in addition some samples from old collections were also studied. The nematodes were isolated by Cobb’s sieving and decantation and modified

Baermann’s funnel techniques. The extracted nematode samples were examined under stereoscopic microscope. Nematodes were simultaneously killed and fixed in hot FA (4:1). Later, the nematodes were transferred into glycerine-alcohol (5:95) and kept in a desiccator for dehydration. Dehydrated nematodes were mounted in anhydrous glycerine on glass slides using wax as sealing material. All Measurements were made on specimens mounted in dehydrated glycerine with an ocular micrometer. De Man’s (1884) formula was used to denote the dimensions of nematodes. All morphological observations and drawings were made on Nikon 80i

DIC microscope and photographs were taken by ProgRes C3 camera mounted on

Olympus BX 50 DIC microscope.

In all, thirteen species belonging to eleven genera, falling under two superfamilies, three families and four subfamilies has been described. Of these ten species which are new to science have been described and illustrated in addition three known species have also been described. Two known species are being reported for the first time from India. The terminology used in the text to describe the parts of stoma is of De Ley et al. (1995).

112

The systematic position of genera and species, described in the present study are given below

I. Order

Rhabditida

II. Suborder

Cephalobina

III. Superfamilies

1. Cephaloboidea 2. Panagrolaimoidea

IV. Families

1. Cephalobidae 3. Brevibuccidae

2. Panagrolaimidae

V. Subfamilies

1. Cephalobinae 3. Tricephalobinae

2. Acrobelinae 4. Brevibuccinae

VI. Genera

1. Pseudacrobeles 7. Stegellata

2. Acrobeles 8. Zeldia

3. Acrobeloides 9. Tricephalobus

4. Cervidellus 10. Brevibucca

5. Chiloplacus 11. Plectonchus

6. Nothacrobeles

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VII. Species

1. Pseudacrobeles ventricauda sp. n. 8. Nothacrobeles punctatus sp. n.

2. Pseudacrobeles mucronata sp. n. 9. Stegellata ophioglossa

3. Acrobeles mariannae 10. Zeldia tridentata

4. Acrobeloides glandulatus sp. n. 11. Tricephalobus quadripapilli sp. n.

5. Cervidellus neoalutus sp. n. 12. Brevibucca postamphidia sp. n.

6. Cervidellus minutus sp. n. 13. Plectonchus coptaxii sp. n.

7. Chiloplacus aligarhensis sp. n.

114

Part – B Ecology

Introduction

Soil is home to many vertebrate and invertebrate species. Invertebrate species largely outnumber the vertebrate species. The functional characteristics of these invertebrates generally depend upon the soil characteristics and thus any changes in soil condition effect the population dynamics of these invertebrates and are easily reflected in various forms.

Soil microfauna, such as protozoa and nematodes, are important constituents of soil foodwebs (Bonkowski, 2004). Their activities regulate the size and function of fungal and bacterial populations in the soil (Ingham et al.,

1985; Poll et al., 2007), plant community composition (De Deyn et al., 2003) and rates of carbon (Bradford et al., 2007) and nitrogen (Standing et al., 2006) turnover. Nematodes are of particular interest because they are the most numerous soil mesofauna and occupy all consumer trophic levels within the soil foodweb. Therefore, their community structure can provide important insights regarding many aspects of ecosystem function (Ritz & Trudgill, 1999; De Ruiter et al., 2005).

The assemblage of plant and soil nematode species occurring in a natural or a managed ecosystem constitutes the nematode community. These communities are sensitive to changes in food supply (Yeates, 1987) and environment (Bongers et al., 1991; Ettema & Bongers, 1993; Freckman &

Ettema, 1993; Samoiloff, 1987; Wasilewska, 1989). Thus, communities also have a significant role in regulating decomposition and nutrient cycling (Anderson et al., 1983; Ingham et al., 1985) and occupy a central position in the soil food web

(Moore & de Ruiter, 1991). When attributes of soil nematode communities are quantified through measures such as diversity index (Shannon & Weaver, 1949)

115 or maturity index (Bongers, 1990; Yeates, 1994), an indication of relative soil biological or ecological health is obtained, which can be used as one measure to address issues of change in ecological condition of soils in agricultural systems.

Since, nematodes are so abundant and omnipresent in ecosystems, they serve as elegant indicators of environmental disturbance (Bongers 1990; Ferris et al., 2001; Yeates, 2003; Höss et al., 2004; Schratzberger et al., 2006; Heininger et al., 2007). Nematodes possess the most important attributes of any prospective bioindicator (Cairns et al., 1993): abundance in virtually all environments, diversity of life strategies and feeding habits (Freckman, 1988; Yeates et al.,

1993), short life cycles, and relatively well-defined sampling procedures. Several attempt have been made by researchers to develop relationships between nematode community structure and succession of natural ecosystems or environmental disturbance (Ettema & Bongers, 1993; Freckman & Ettema, 1993;

Freckman & Virginia, 1997; De Goede & Dekker, 1993; Wasilewska, 1994;

Yeates & Bird, 1994).

Soil microbes play an important role in plant nutrient cycling in organic farming (Allison, 1973). Additions of organic matter to soil are expected to increase numbers of bacteriovores and fungivorous nematodes and decrease numbers of plant-parasitic nematodes (Bohlen & Edwards, 1994; Freckman,

1988; Griffiths et al., 1994). Applications of manure add both organic matter and microbes, a source of food for the nematodes (Andrén & Lagerlöf, 1983; Weiss

& Larink, 1991). When bacteria are plentiful in soil, bacteriovorous nematodes may discharge amino acids in substantial amounts. However, as bacterial population decrease, nematodes begin to starve, and protein catabolism for

116 maintenance energy requirements leads to increased ammonium excretion by nematodes (Anderson et al., 1983). Nitrogen content appears to be an important measure of potential microbial activity and, subsequently, the rate of decomposition (Neely et al., 1991).

Prior to the initiation of research on C. elegans, other than the activities of a few taxonomists, most studies on soil nematodes centered on the biology and management of those that cause damage to higher plants. A milestone in the ecology of free-living soil nematodes was the seven-year study in Denmark by

Overgaard Nielsen (1949) on nematode faunae of different soils, their physiological ecology and even their ecosystem services. Further notable ecological contributions emerged in the 1970s and 1980s. Centres of ecological study on nematodes developed in Sweden (Sohlenius, 1973), Poland (Prejs, 1970;

Wasilewska, 1970), Italy (Zullini, 1976), and Russia (Tsalolikhin, 1976). In the

USA, there was a surge of activity in soil ecology at the National Resource

Ecology Laboratory in Colorado Springs, led by Coleman and others (Yeates &

Coleman, 1982), and similar activity at the Institute of Ecology of the University of Georgia, led by Crossley and colleagues (Stinner & Crossley, 1982). In the same time period, Yeates was developing a very productive programme on the ecology of soil nematodes in New Zealand (Yeates, 1979). A significant contribution was the publication of the PhD research of Ingham, with its accompanying review of preceding studies, in which the functional significance of bacterivore and fungivore nematodes was established by the demonstration that their excretion of nitrogen in excess of structural and metabolic needs stimulated plant growth (Ingham et al., 1985).

117

The ecological classification of terrestrial nematodes has usually been based on their feeding biology (trophic functions) and on the life strategies viz. colonizers vs persiters (Bongers, 1990). Yeates et al., (1993) categorized terrestrial nematodes into eight feeding groups, but most ecologists classify soil nematodes into five feeding groups as discussed below (Yeates, 1998, Yeates &

Bongers, 1999).

1. Plant feeding/herbivores: - Nematodes feeding on vascular plants use a

tylenchid stylet/ dorylaimoid stylet or onchiostyle. They may be further

categorised on the habit of feeding an area of plant on which they feed.

2. Hyphal feeding/Fungivores:- Nematodes in this category puncture fungal

hyphae by a stylet with narrow lumen.

3. Bacterial feeding/bacteriovores:- This category includes species that feed

on any prokaryotic food source, through a narrow or broad stoma. They may

also ingest other types of food. Soil stages of parasites of vertebrates and

invertebrates are also included in this category.

4. Predators:- Feed on other nematodes or small invertebrates such as rotifers

and enchytraieds. They may be either ingestors or piercers.

5. Omnivores:- They appear to feed on a range of food source. It is usual to

restrict the term omnivore to some dorylaimids.

Within the five groups, strong relationship are found between herbivores and fungal feeders, between herbivores and predators and between fungal feeders and predators (Yeates et al.,1993 and Gomes et al., 2003). Degree of correlation between different trophic groups is calculated by using the Karl Pearson’s coefficient of correlation. It is used to measure the degree of relationship between

118 two or more variables, which is based on arithmetic mean and/or standard deviation.

The idea of using ecological indices as indicators of ecosystem quality

(e.g. diversity, stability, and resilience) has received increased attention over the last decade. Indices may be useful tools because they not only provide quantitative means to characterize an ecosystem, but also to compare different ecosystems (Ferris et al., 1996; Porazinska et al.,1998; Yeates & Bird, 1994; and

Yeates et al.,1997). Based on the densities of genera and trophic groups, ecological indices of the nematode community are derived. The Shannon-Weaver diversity index (Shannon & Weaver, 1949) is used to compare diversity of either genera or trophic groups, and Simpson index (1949) is used to compare either generic or trophic dominance. Maturity index Bongers (1990) and Yeates (1994) is a semi-quantitative measure since it takes into consideration biological and ecological characteristics of individual nematode species comprising a particular community and these indices seems to offer better prospects for detecting and sufficiently illustrating changes in the soil environment. The maturity index is calculated as a weighted mean of the c-p values of nematodes in the sample.

Bongers (1990) defined two types of maturity indices: Maturity index (MI) which includes nematodes belonging to all feeding types except herbivores, and Plant parasitic index (PPI) which includes herbivores only. In general, the higher a maturity index value, the more mature and stable the ecosystem. Based on effects of the geographic distribution of nematodes, nematode feeding types, soils and succession. Bongers et al., (1995) demonstrated that under certain conditions the

PPI and MI behave in opposite manners and suggested that an increase in the

119

PPI/MI ratio might reflect ecosystem enrichment. It has been found that PPI/MI is an effective indicator of enrichment in agro-ecosystems (Ferris et al., 2001).

The combination of nematode feeding groups and cp scaling into functional guilds have developed nematode faunal analysis into a powerful tool which can be used as an indicator of soil health and soil food web conditions.

Various functional guilds of nematodes have been described to compute

Enrichment index (EI) and Structure index (SI). Enrichment index is based on expected responsiveness of the opportunistic guilds (Ba1) to the food resource enrichment. Thus, EI describes whether a soil ecosystem is nutrient enriched

(high EI) or depleted (low EI). The SI represents an aggregation of functional guilds with cp values ranging from 3-5. SI describes whether soil ecosystem is structured/ matured (high SI) or disturbed/ degraded (low SI). In addition to these indices, Channel index (CI) is also calculated, which is the percentage of fungivores among the total of fungivores and opportunistic bacteriovores to describe the dominant decomposition channels in the food web. The CI also provides a mean of tracking succession between fungivore and bacteriovore nematodes as organic resources are supplied and depleted in agricultural systems

(Ruess & Ferris, 2002). Decomposition rates of readily degraded materials in bacterial pathways are expected to be faster than that in fungal pathways where materials may be more complex. Due to the similarity of C/N of fungi and fungivore nematodes, mineralization rates in fungal channels is slower than those in bacterial channels where there is greater difference between C/N ratios of predators and prey (Ingham et al., 1985; Ferris et al., 1997; Chen & Ferris, 1999;

Okada & Ferris, 2001). Such analysis provides slightly different information than

120 other analysis based on biomass or diversity and take into consideration both descriptive and quantitative information on the soil ecosystem. Further, the redistribution of bacteria to new food sources by survival of passage through the nematode intestine is an important accelerator of decomposition process

(Wasilewska et al., 1981; Freckman, 1988) for which fungivore nematodes probably do not provide an equivalent function in the fungal channel.

Nematode faunal analysis is evolving as a powerful bioindicator of the soil condition and of structural and functional attributes of the soil food web

(Bongers & Ferris, 1999; Neher, 2001). Recent developments of such analyses include recognition of an enrichment trajectory and a structure trajectory. The latter measures the abundance of trophic linkages in the food web and the probability of regulatory effects on opportunist populations through exploitation and competition. The enrichment trajectory reflects supply-side characteristics of the food web and the increase in the primary consumers of incoming organic material (Ferris et al., 2001). Food webs become enriched when disturbance occurs and resources become available due to external input, organism mortality, turnover, or favorable shifts in the environment (Odum, 1985; Van Veen &

Kuikeman, 1990). The enrichment-opportunist bacteriovore nematode guild includes species in the families Rhabditidae, Panagrolaimidae and Diplogastridae

(Bongers & Ferris, 1999; Ferris et al., 2001). They are classified as cp-1 organisms, characterized by short generation time, small eggs and high fecundity, in the colonizer-persister scale of Bongers (1990). They appear to feed continuously in the enriched media and then form metabolically suppressed dauerlarvae as resources are diminished. As microbial blooms fade, enrichment-

121 oppurtunist microbivores may be replaced by general-opportunist with specialized morphological, physiological and behavioral adaptations for more deliberate feeding on less-available resources. The general-opportunist nematodes, classified as cp-2, are predominantly bacterial scavengers in the

Cephalobidae and fungal-feeders in the Aphelenchidae, Aphelenchoididae and

Anguinidae. Increased abundance of fungal-feeding opportunists occurs when the available organic pool is conductive to fungal decomposition as, for example, when complex organic material becomes available in the soil or when fungal activity is enhanced under conditions less favorable for bacterial decomposition

(Eitminaviĕūté et al., 1976; Wasilewska et al., 1981). In fact, nematodes in the general-opportunist guild commence to increase with the initial enrichment, but at slower rate than the enrichment opportunists so that they become successionally predominant as the latter guild is declining (Bongers, 1990; Ferris et al., 1996b, 2001; Bongers & Bongers, 1998; Bongers & Ferris, 1999; Chen &

Ferris, 2000).

Studies are being carried out throughout the world on various aspects of nematode ecology. Most of the studies are concentrating on the impact of heavy metals on nematode assembleges and secondary succession of nematode guilds.

Zhang et al. (2007) studied responses of nematode assemblages to Cu and Zn pollution on corn fields near a copper smelter in Northeast China. Dechang et al.

(2009) & Tomar et al. (2009) studied effects of heavy metals on nematode functional guilds in agro-ecosystems of Shenyang, Liaoning province, China and reported that the concentrations of lead were most significant at distance of 20 m from the highway, and than concentration gradually decreased to further

122 distances. Cheng & Grewal (2009) studied dynamics of soil food web under urban landscape and reported that anthropogenic activities resulting in the loss of top soil can have profound effect on the structure of soil food web, which may severely limit its capacity to support optimal nutrient cycling. Mahran et al.

(2009) studied response of nematode communities to hog manuring and reported that hog manuring is effective in killing plant parasitic nematodes. Hánèl (2010) studied succession of nematodes in agro-ecosystems and compared it with abandoned fields in South Bohemia. Biodiversity and trophic structure of soil nematode communities in subtropical ecosystems was studied by Bierdermann &

Boutton (2010). Their study mainly focused on nematode responses to woody plant encroachment in urban areas. They reported that energy flow through nematode food webs in grasslands appear relatively diversified and SI indicated that nematode communities within old clusters were more simplified than those in grassland due to reduction in densities of omnivores and predators. Soil nematode communities of a banana planted agro-ecosystem were studied by

Tabarant et al. (2011). They concluded that plant residue and bagasse which are mainly composed of cellulose and lignins which are difficult to decompose.

These chemicals mainly favor fungal decomposition pathways and permitted development of carnivorous nematodes and thus increasing channel index. Park et al. (2011) studied effects of heavy metal contamination in abandoned mines.

They examined two areas one with heavy metal infection from mines and another control area which had no infection and found that diversity of nematodes was less in contaminated area as compared with non contaminated area. Liu et al.,

(2011) studied effects of biological crusts on soil nematode communities and

123 found that nematode abundances, generic richness and food web based indices as

EI and SI positively correlated with different crust ages.

The nematodes have been widely studied in India in contrast of plant parasites and control of nematode menace in agro-ecosystems. Various researchers have used nematodes for studying effects of organic amendments in field and micro-plot experiments. Singh (1970) studied control of plant parasitic nematodes with organic soil amendments. Akhtar (1993, 1999 & 2000) studied possible relation of organic soil amendments and nematodes. Devi & Das (1998) studied effects of organic amendments of root knot nematodes. Hassan et al.

(2008 & 2009) studied nematodes of Zea mays and their possible control through organic amendments. There are some sporadic reports of study of nematode diversity in different ecosystems. Tomar et al. (2006) reported diversity of nematodes at a Mango orchard in Aligarh. Baniyamuddin et al. (2007) studied functional diversity of nematodes of natural forests in Arunachal Pradesh. Tomar

& Ahmad (2009) studied nematode community in a natural woodland of Aligarh region, and reported it to be a stable ecosystem on the basis of maturity and plant parasitic indices.

The aim of the present study was to investigate nematode communities and temporal changes in the nematode fauna of two different habitats (crop field and natural wasteland), for a period of one year. These two habitats were located at a distance of 6 Kms from each other. Specifically, population dynamics, faunal analysis, and community composition of soil nematodes have been studied to assess the role of nematodes as indicators of soil condition.

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Materials & Methods

Site description: - The experimental sites a) Crop field (CF) and b) Wasteland

(WL) were selected on the basis of differences in their vegetation and soil disturbance. Both the sampling sites were located in Aligarh district. The climate of the region, in general the blocks in the west are drier as compared to those in the east. The temperature rises as high as 44.6˚C during summer and drops down to as low as 4.8˚C during winters. The mean maximum and mean minimum temperature of district Aligarh is 26.7˚C and 15.5˚C respectively. Monsoon starts in July and runs to September. While in winter season, the region receives very few showers. The mean annual rainfall of the district is 434 mm, mean relative humidity 65%. Thus the Climate of the district Aligarh is Semi-Arid. Served by numerous rivers, rivulets and canals of the Ganga. Few rivers like Karwan,

Rutba and Kali pass through the district but remain almost dry except during rainy season.

Site a):- The crop field situated about 14 Kms from Aligarh city, on Aligarh –

Moradabad highway (27° 57′ N, 78° 10′ E) was selected. The field was cultivated under annual conventional cropping system whereby wheat was the only crop sown during the sampling time with fallow periods in between. During sampling crop was at different stages of development. Organic amendments were added to the crop field in form of manures during September-October. Chemical fertilizer mainly NPK were added to field during December-January

Site b) :- This site was natural wasteland, more than two decades old, situated about 8 Kms from Aligarh city on Aligarh – Moradabad highway (27° 55′ N, 78°

54′ E) was selected for sampling. The wasteland covers more than two sq. Km

125 area on either side of highway. Wasteland usually remained dry and bare during most of the time except monsoon. During monsoon most parts of the area were covered by grasses.

Sampling

Soil samples from crop field were collected following the growth pattern of the crop, simultaneously samples were also collected from wasteland. In

Aligarh district monsoon starts in July and runs to September. Wheat was sown during the month of October/November and harvested during February/March.

Sampling was undertaken on eight occasions from June 2008 to April 2009 at different stages of development of wheat crop including the fallow periods before and after the cropping period. Each soil sample consists of five cores (1 cm2 cross sectional area) from a depth of 0-10 cm. All the samples were collected windward in N-W direction. Samples were tagged, stored in sealed plastic bags and brought to laboratory for further processing. For sampling from both the areas a diagonal transect was selected and samples were collected from the same.

Processing of soil samples

About 100 cc of soil from each sample was processed by Cobb (1915) sieving and decantation and modified Baermann’s funnel technique as discussed earlier in Part A.

Isolation and Killing & Fixation of Nematodes

The isolation, killing and fixation of nematodes were done by the same process as it was done in Part A.

126

Counting of Nematodes

Population count of nematodes was made using Syracuse counting dish.

The suspension was made homogenous by bubbling with pipette thoroughly before taking 2 ml of nematode suspension in the dish for counting. Counting of each sample was done three times and mean was obtained. The final population was obtained by multiplying final quantity of nematode suspension (50 ml) with mean number of nematodes counted and dividing by the quantity of suspension used for counting (2 ml).

Identification

Mass slides containing about two hundred nematodes per sample were prepared for identification. Identification up to generic level was done mainly using Goodey (1963); Jairajpuri & Khan (1982); Andrássy (1984, 2005), Siddiqi

(1986), Jairajpuri & Ahmad (1992); Ahmad (1996). Trophic group were allocated according to Yeates et al. (1993) and cp groups were assigned after Bongers

(1990).

Data Analysis

Nematode diversity was described using the univariate measures of the

Shanon index calculated at genus level (H’) and multivariate analysis was performed by ANOVA using statistical programme SPSS. Shanon’s diversity

(H’) was calculated by SPECDIVE. Nematodes were assigned to five main trophic groups (bacteriovores, fungivores, herbivores, omnivores and predators) after Yeates et al. (1993). Maturity index (MI) was calculated to estimate the relative state of two ecosystems studied. Trophic diversity was calculated by the

127 trophic diversity index, (TDI) (Heip et al., 1988). Structure index (SI) and enrichment index (EI) were calculated to determine the relative stability of the ecosystem studied. Nematode channel ratio was calculated to reflect differences in the mineralization of dead and live plant tissues. (Wasilewska, 1994). In all the above mentioned indices, nematode families were allocated cp scale according to their perceived life history strategy.

Detailed description of the formulae used are given below

Shannon’s diversity (H′) = −Σ (pi ln pi)

Maturity Index (MI)

n   . ifiVMI i1

Where Vi= cp value of the ith taxon.

f(i) the frequency of that taxon in a sample

* Maturity index (MI) is calculated as the weighted mean of the individual

cp value.

Plant Parasitic index (PPI)

PPI  PPiXi / Xi

Where, Ppi = PP value assigned to taxon i according to Bongers (1990).

Xi = abundance of taxon i in the sample.

128

Nematode Channel Ratio (NCR)

B NCR  B  F

Where, B = Total abundance of Bacterial feeding nematodes

F = Total abundance of Fungal feeding nematodes.

Enrichment index (EI) = (e/e+b) x100

Structure index (SI) = (s/s+b) x100

where e, b & s are sum products of assigned weights and number of

individuals of all genera (Table 1,2).

Trophic Diversity index (TDI) = 1 ⁄ ∑pi²

where pi² is the proportional contribution of ith trophic group.

129

Table 1:- Nematode functional guilds in different Food web conditions.

Basal (b) Structured (s) Enriched (e)

Ba2- Cephalobidae Ba3- Prismatolaimidae Ba1- Rhabditidae,

Panagrolaimidae

Fu2- Aphelenchidae, Fu3- Diptherophoridae

Aphelenchoididae

Anguinidae.

Fu4- Leptonchidae

Pr2- Aphelenchid Carnivores

Pr3- Tripylidae

Pr4- Mononchidae

Pr5- Discolaimidae

Om4- Dorylaimidae

Om5- Thornenematidae,

Qudsianematidae

The numbers used in the table denotes the assigned c-p value to the trophic groups as follows:

Ba- Bacteriovores

Fu- Fungivores

Pr- Predators

Om- Omnivores

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Results

Nematode Diversity

During the present course of study a total of 50 genera belonging to 10 orders and 30 families were encountered from the crop field (CF) while 46 genera belonging to 8 orders and 25 families occurred in the wasteland (WL). The number of genera varied from 13 to 23 per sample in crop field while in wasteland it ranged from 7 to 21 per sample. In terms of abundance the number varied from 105 to 1178 individuals in crop field and 106 to 568 in wasteland per

100 cc of soil. Acrobeloides was the most abundant genus in crop field while

Dorylaimellus was the most abundant genus in the wasteland.

In the crop field, in terms of number of genera (Fig. 1, A) the Order

Dorylaimida was most frequent (30%) with 15 genera under 8 families, followed by Rhabditida (22%) with 11 genera under 4 families, Tylenchida (20%) with 10 genera under 6 families, Araeolaimida (8%) with 4 genera under 3 families,

Aphelenchida (6%) with 3 genera under 3 families, Enoplida (4%) with 2 genera under 2 families & Monhysterida (4%) represented by 2 genera under 1 family, while Alaimida (2%), Diptherophorida (2%) and Chromadorida (2%) were represented by 1 genus each. However, in wasteland, (Fig. 1, C) Order

Dorylaimida (32%) was most prevalent with 7 families representing 15 genera followed by Tylenchida (22%) with 10 genera under 6 families, Rhabditida

(22%) with 4 families representing 10 genera, Aphelenchida (7%) and

Chromadorida (7%) were represented by 3 genera each under 3 families and & 1 family respectively, while Araeolaimida (4%) and Monhysterida (4%) were represented by 2 genera each under 2 families and 1 family respectively and

Enoplida (2%) was the least prevalent with single genus.

131

In terms of number of individuals (Fig. 1, B), Rhabditida (44%) was most abundant, followed by Tylenchida (19%), Dorylaimida (12%), Aphelenchida

(11%), Araeolaimida (8%), Enoplida (2%), Alaimida, Chromadorida,

Monhysterida and Diptherophorida (1% each) in crop field. While in wasteland

(Fig. 1, D) Rhabditida (33%) was most abundant, followed by Dorylaimida

(27%), Aphelenchida (11%), Tylenchida (10%), Chromadorida (9%),

Araeolaimida (5%), Enoplida (4%) and Monhysterida (1%).

Trophic diversity

In the crop field (Fig. 2, A), bacteriovores constituted the most dominant group in terms of number of genera and abundance and were represented by 20 genera. This was followed by herbivores, fungivores, omnivores and predators, which were represented by 9, 8, 7 & 6 genera respectively. In terms of number of individuals (Fig. 2, B) bacteriovores (58%) was the most abundant group, followed by fungivores (21%), herbivores (13%), omnivores (5%) and predators

(3%). The trophic diversity index (TDI) of the area ranged from 1.03-1.25

(1.1±0.07). Among bacteriovores the genus Acrobeloides was most dominant while the genera Hoplolaimus, Aphelenchus, Moshajia and Discolaimus were most dominant among herbivores, fungivores, omnivores and predators respectively. Least dominant genera among bacteriovores, herbivores, omnivores, fungivores and predators were Drilocephalobus, Hemicriconemoides,

Thornenema, Leptonchus and Tripyla respectively (Table 2). Bacteriovores, fungivores and herbivores were present in all samples while omnivores and predators were absent from two samples each. In the crop field (Fig. 3) all

132 nematode population remained relatively low from June to December. Thereafter the bacteriovores increased in numbers with a peak population in March followed by a sharp decline. The fungivores followed a somewhat similar pattern but the population remained comparatively low. All other groups showed peak population in January but their number was very low.

In the wasteland (Fig. 2, C) also bacteriovores constituted the most dominant group in terms of number of genera and abundance and were represented by 18 genera. This was followed by herbivores with 10 genera, omnivores with 7 genera, fungivores with 6 genera and predators with 5 genera.

The bacteriovores (51%) was the most abundant group in terms of number followed by fungivores (29%), herbivores (11%), omnivores (6%) and predators

(3%) (Fig. 2, D). The trophic diversity index (TDI) of the area ranged from 1.05-

1.23 (1.12±0.06). Among bacteriovores, the genus Acrobeles was dominant, while the Ditylenchus, Moshajia, Dorylaimellus and Seinura were most dominant among herbivores, omnivores, fungivores and predators respectively. Least dominant genera among various trophic groups were Stegellata, Psilenchus,

Tylencholaimus, Epidorylaimus and Discolaimoides (Table 3). All the samples contained bacteriovores and fungivores, while herbivores were absent in one sample and omnivores and predators were not present in four and five sample respectively. In the wasteland (Fig. 3), population of all groups except herbivores remained uniform from June to October, dipped in December and peaked of in

January followed by a rapid decline thereafter. At the peak population bacteriovores were in maximum number followed by fungivores and omnivores.

The herbivore population remained relatively low and showed a peak in October.

133

Nematode Community Dynamics

The diversity of nematode fauna in agroecosystems and their relationships to soil processes suggests that they are potential bioindicators. However, the effects of plants, soil types and nematode biogeography mean a ‘functional group’ may be a better indicator than particular nematodes. Permanent grassland may be regarded as providing a baseline for nematode diversity in a given soil.

The relative abundance of fungal-feeding and bacterial-feeding nematodes serve as sensitive indicator of management changes (Yeates & Bongers, 1999). For assessing the community dynamics and role of nematodes in the agroecosystems, various indices such as Shannon’s diversity index (H’), Maturity index (MI) including plant parasitic families, Maturity index 2-5 (MI25, excluding Ba1 functional guild), Plant parasitic index (PPI), Nematode channel ratio (NCR) and

PPI/MI were calculated. The percent abundance of cephalobids, tylenchids, dorylaims and other nematodes were also obtained.

Food web diagnostics of the ecosystem was studied in terms of

Enrichment index (EI), Structure index (SI) and Basal index (BI) following the weighted faunal analysis concept of Ferris et al. (2001).

Shannon’s diversity index (H’) in crop field was found to be 2.21–2.73

(2.45±0.19) and in wasteland it ranged from 1.88–2.54 (2.17±0.22). The maturity index (MI) ranged from 2.1–2.59 (2.35±0.18) in crop field and 2.36–3.64

(2.9±0.41) in wasteland. MI25 ranged from 2.13–2.59 (2.4±0.18) and 2.37–3.66

(2.91±0.41) in crop field and wasteland respectively. The plant parasitic index

(PPI) for the crop field varied from 2.21–3.19 (2.73±0.33) while it was 2.0–3.0

134

(2.65±0.41) for wasteland. Nematode channel ratio (NCR) was found to be 0.61–

0.94 (0.76±0.11) and 0.49–0.8 (0.63±0.1) and the values for PPI/MI were 1.01–

1.38 (1.16±0.13) and 0.72–1.28 (0.99±0.21) for crop field and wasteland respectively (Table 4 & 5). Comparison of crop field samples for indices revealed that MI was almost constant for all sampling times, while PPI was highest during

June which gradually decreased till December (i.e. growth phase) and than it increased gradually. NCR also was almost constant throughout. In wasteland MI showed a gradual increase till December and then gradually decreased, while PPI and NCR were almost constant for the sampling times (Table 4 & 5, Fig. 4).

The enrichment index (EI) ranged from 13.5–41.1 (26.5±9.8) and 5.2–

38.9 (17.9±10.6) and the structure index (SI) was found to be 22.7–64.2

(47.7±15.8) and 43.3–90 (70.5±15) in the crop field and wasteland respectively.

Basal index (BI) varied from 31.47–68.9 (43.8±13.08) in the crop field and 9.76–

49.3 (26.3±12.15) in the wasteland (Table 4 & 5). Comparison of food web indices for crop field indicated that BI was highest during December (i.e. growth phase) showing a linear spline, while the values for SI gradually increased with a sudden decrease in December. The EI values also followed same pattern as of SI.

In wasteland SI gradually increased till December and then remains constant while BI gradually decreased till December and increased constantly for the next sampling times. EI shows a sudden dip in the month of October and then it gradually increased till the end of sampling (Table 4 & 5, Fig. 5).

The abundance of cephalobids per sample ranged from 32.2-58.6%

(42.5±9.4) in crop field and 14.4-44.6% (31.8±9.2) in wasteland while of tylenchids it ranged from 8.9-39.8% (19.4±9.8) in crop field and 1.4-22.3%

135

(10.3±6.6) in wasteland. The dorylaims abundance varied from 1.9-19.5%

(11.7±6.2) and 12.6-44.9% (27.2±10.1) and others groups from 14.7-38.2%

(26.4±8) and 12.3-36.3% (30.7±8.3) in crop field and wasteland respectively

(Table 4 & 5, Fig. 6).

In crop field (Table 6), population of dorylaims show very high degree of positive correlation with MI and SI (Fig. 7, A & B), and very significant negative correlation with BI (Fig. 7, C). With all other indices dorylaims show either negative correlation or almost no correlation. Population of tylenchids show low level of positive correlation with PPI/MI ratio and to certain level with PPI (Fig.

7, D), while some degree of negative correlation with MI and SI. Population of cephalobids show a low level of positive correlation with PPI and low level of negative correlation with MI while almost no correlation was found with EI ans

SI. Almost no correlation was found with MI while it was negatively correlated with PPI, EI and SI.

In Wasteland (Table 6), population of dorylaims showed very high degree of positive correlation with MI and SI (Fig. 8, A & B) while significant negative correlation was found with PPI/MI ratio and BI. Population of tylenchids show some degree of positive correlation with MI, PPI and SI while they are negatively correlated to some degree with EI, BI and PPI/MI ratio. Population of cephalobids showed high degree of negative correlation with MI (Fig. 8, C) and

SI while significant positive correlation was found with H′ and PPI/MI ratio and upto certain level with PPI, however, there was almost no correlation was found with EI. Other nematodes show some degree of positive correlation with EI while certain level of negative correlation with MI, PPI and SI was observed.

136

Significant negative correlation was also observed between population of dorylaims and cephalobids (Fig. 8, D).

137

Table 2: Population structure of soil inhabiting nematodes of crop field

Genera N* AF% MD RD% Bacteriovores Acrobeles 27 88.89 7.95 3.60 Acrobeloides 40 133.33 35.45 16.05 Alaimus 8 27.78 1.48 0.67 Cephalobus 37 122.22 23.55 10.66 Cervidellus 5 16.67 0.63 0.28 Chiloplacus 40 133.33 21.53 9.75 Chromadora 8 27.78 2.03 0.92 Chronogaster 12 38.89 3.05 1.38 Drilocephalobus 2 5.56 0.15 0.07 Eucephalobus 15 50.00 2.83 1.28 Mesorhabditis 25 83.33 5.25 2.38 Monhystera 7 22.22 2.83 1.28 Monhystrella 3 11.11 0.13 0.06 Panagrolaimus 8 27.78 0.50 0.23 Plectus 27 88.89 3.25 1.47 Prismatolaimus 20 66.67 5.53 2.50 Rhabdolaimus 20 66.67 10.33 4.67 Stegellata 7 22.22 1.15 0.52 Wilsonema 3 11.11 0.25 0.11 Zeldia 15 50.00 1.10 0.50 Fungivores Aphelenchoides 30 100.00 10.58 4.79 Aphelenchus 33 111.11 11.63 5.26 Basirotyleptus 18 61.11 8.18 3.70 Dorylaimellus 20 66.67 6.20 2.81 Filenchus 3 11.11 0.20 0.09 Leptonchus 3 11.11 0.13 0.06 Tylencholaimus 12 38.89 0.93 0.42 Tylenchus 28 94.44 7.63 3.45 Herbivores Boleodorus 5 16.67 0.65 0.29 Ditylenchus 25 83.33 8.95 4.05 Helicotylenchus 12 38.89 0.88 0.40 Hemicriconemoides 2 5.56 0.05 0.02 Hoplolaimus 28 94.44 8.75 3.96 Merlinius 5 16.67 0.43 0.19 Pratylenchus 5 16.67 0.40 0.18 Trichodorus 5 16.67 1.03 0.46 Tylenchorhynchus 27 88.89 8.80 3.98

138

Omnivores Epidorylaimus 3 11.11 0.08 0.03 Eudorylaimus 8 27.78 1.10 0.50 Latocephalus 3 11.11 0.05 0.02 Moshajia 32 105.56 8.30 3.76 Oriverutus 2 5.56 0.08 0.03 Thonus 8 27.78 0.63 0.28 Thornenema 2 5.56 0.05 0.02 Predators Aporcelaimellus 10 33.33 0.93 0.42 Aquatides 5 16.67 0.70 0.32 Discolaimus 20 66.67 2.00 0.91 Discolaimoides 8 27.78 0.93 0.42 Seinura 10 33.33 1.73 0.78 Tripyla 2 5.56 0.03 0.01

*Mean of five replicates

139

Table 3: Population structure of soil inhabiting nematodes of wasteland

Genera N* AF% MD RD% Bacteriovores Achromadora 3 8.33 1.53 1.09 Acrobeles 32 79.17 5.83 4.17 Acrobeloides 25 62.50 7.48 5.35 Cephalobus 28 70.83 14.15 10.14 Cervidellus 5 12.50 0.20 0.14 Chiloplacus 28 70.83 13.83 9.90 Chromadora 3 8.33 0.58 0.41 Eucephalobus 17 41.67 2.23 1.59 Geomonhystera 3 8.33 0.15 0.11 Mesorhabditis 8 20.83 0.60 0.43 Monhystrella 2 4.17 0.25 0.18 Monochromadora 27 66.67 11.13 7.97 Panagrolaimus 7 16.67 0.65 0.47 Plectus 27 66.67 2.10 1.50 Prismatolaimus 20 50.00 6.18 4.42 Protorhabditis 8 20.83 0.48 0.34 Rhabdolaimus 28 70.83 4.60 3.30 Stegellata 2 4.17 0.15 0.11 Fungivores Aphelenchoides 35 87.50 7.68 5.50 Aphelenchus 25 62.50 5.88 4.21 Basirotyleptus 5 12.50 0.30 0.21 Belondira 5 12.50 0.95 0.68 Dorylaimellus 40 100.00 24.95 17.87 Tylencholaimus 3 8.33 0.23 0.16 Omnivores Dorylaimoides 2 4.17 0.10 0.07 Epidorylaimus 2 4.17 0.05 0.04 Eudorylaimus 8 20.83 0.50 0.36 Latocephalus 8 20.83 0.65 0.47 Mesodorylaimus 15 37.50 2.55 1.83 Moshajia 22 54.17 3.85 2.76 Thonus 3 8.33 0.18 0.13 Herbivores Boleodorus 5 12.50 0.68 0.48 Ditylenchus 17 41.67 2.58 1.84 Helicotylenchus 13 33.33 0.85 0.61 Heterodera 2 4.17 0.90 0.64 Hoplolaimus 12 29.17 1.68 1.20 Merlinius 3 8.33 0.98 0.70

140

Pratylenchus 12 29.17 5.63 4.03 Psilenchus 2 4.17 0.13 0.09 Tylenchorhynchus 8 20.83 0.55 0.39 Tylenchus 10 25.00 1.08 0.77 Predators Aporcelaimellus 10 25.00 1.35 0.97 Aquatides 5 12.50 0.23 0.16 Discolaimoides 3 8.33 0.20 0.14 Discolaimus 13 33.33 1.65 1.18 Seinura 15 37.50 1.23 0.88

*Mean of five replicates

141

Table 4: Characteristics of crop field

June September October December January February March April Mean±SD H' 2.24 2.21 2.63 2.33 2.73 2.53 2.34 2.56 2.45±0.19 MI 2.32 2.31 2.38 2.10 2.50 2.12 2.49 2.59 2.35±0.18 MI25 2.33 2.42 2.50 2.13 2.58 2.16 2.50 2.59 2.4±0.18 PPI 3.19 3.00 2.83 2.45 2.56 2.21 3.00 2.60 2.73±0.33 PPI/MI 1.38 1.30 1.19 1.16 1.03 1.04 1.21 1.01 1.16±0.13 EI 26.75 26.19 41.14 13.51 38.24 29.33 15.19 22.04 26.5±9.8 SI 43.62 50.77 56.56 22.70 60.47 25.59 57.44 64.25 47.7±15.8 BI 46.92 41.01 33.90 68.91 31.47 56.11 39.56 32.41 43.8±13.08 TDI 1.26 1.05 1.04 1.06 1.12 1.06 1.05 1.10 1.1±0.07 NCR 0.74 0.81 0.83 0.94 0.61 0.74 0.76 0.64 0.76±0.11

% Cephalobids 32.26 58.63 51.13 45.28 36.36 37.06 46.32 33.02 42.5±9.4 % Tylenchids 39.78 13.40 13.15 24.67 22.64 18.95 8.93 13.62 19.4±9.8 % Dorylaims 6.89 13.27 12.33 1.94 19.51 5.83 17.00 16.92 11.7±6.2 % Others 21.07 14.69 23.39 28.11 21.48 38.16 27.74 36.44 26.4±8 Table 5: Characteristics of wasteland

June September October December January February March April Mean±SD H' 2.28 2.08 1.97 1.88 2.17 2.06 2.54 2.39 2.17±0.22 MI 2.36 2.60 3.23 3.64 2.91 3.05 2.72 2.65 2.9±0.41 MI25 2.37 2.64 3.28 3.66 2.92 3.07 2.72 2.65 2.91±0.41 PPI 3.00 3.00 2.93 2.47 2.11 2.67 2.00 3.00 2.65±0.41 PPI/MI 1.28 1.18 0.91 0.72 0.74 0.87 1.09 1.13 0.99±0.21 EI 20.16 38.96 5.21 13.74 15.26 26.44 13.60 9.92 17.9±10.6 SI 43.29 57.67 83.24 90.02 72.74 80.91 67.72 68.12 70.5±15 BI 49.33 30.52 16.61 9.77 25.43 17.56 30.69 30.89 43.8±13.1 TDI 1.08 1.15 1.14 1.24 1.10 1.15 1.09 1.05 1.12±0.06 NCR 0.70 0.54 0.59 0.49 0.65 0.58 0.68 0.80 0.63±0.1

% Cephalobids 44.59 32.31 33.41 14.42 26.56 26.93 38.30 37.69 31.8±9.2 % Tylenchids 6.46 12.89 22.37 15.85 6.90 6.78 1.42 9.82 10.3±6.6 % Dorylaims 12.63 20.87 31.91 44.94 31.69 30.58 27.25 17.63 27.2±10.1 % Others 36.31 33.94 12.31 24.79 34.85 35.71 33.03 34.86 30.7±8.3 Crop field

H MI PPI PPI/MI EI SI BI % D % T % C % O H 1 MI .366 1 PPI -.549 .364 1 PPI/MI -.793* -.197 .841** 1 EI .643 .181 -.036 -.143 1 SI .342 .967** .456 -.081 .327 1 BI -.458 -.902** -.374 .133 -.534 -.964** 1 % D .433 .918** .242 -.283 .294 .930** -.913** 1 % T -.244 -.347 .144 .375 .042 -.401 .378 -.516 1 % C -.326 -.175 .270 .378 -.009 .020 .009 .019 -.539 1 % O .347 -.085 -.687 -.687 -.271 -.258 .239 -.171 -.190 -.534 1

Wasteland

H MI PPI PPIMI EI SI BI % D % T % C % O H 1 MI -.718* 1 PPI -.255 -.262 1 PPIMI .588 -.863** .514 1 EI -.077 -.426 .250 .375 1 SI -.617 .937** -.208 -.818* -.403 1 BI .664 -.938** .252 .848** .285 -.988** 1 % D -.614 .954** -.512 -.911** -.346 .877** -.907** 1 % T -.758* .565 .492 -.288 -.247 .555 -.527 .371 1 % C .723* -.869** .330 .869** .067 -.794* .855** -.899** -.355 1 % O .542 -.641 -.133 .370 .542 -.623 .569 -.509 -.848** .262 1

** Correlation is significant at the 0.01 levels * Correlation is significant at the 0.05 levels

% D - % Dorylaims; % T - % Tyelnchids; % C - % Cephalobids; % O - % Others

Table 6: Correlation coefficient between different indices and nematode groups in crop field and wasteland

144

Fig.1: Ordinal diversity and abundance of nematodes in a Crop field (A & B) and wasteland (C & D)

145 A

Fig. 2: Trophic diversity and abundance of nematodes in a crop field (A & B) and wasteland (C & D)

146 Fig. 3: Population structure of different trophic groups during variuos sampling times

147 Fig. 4 : Relation between different indices (MI, PPI, NCR) in crop field and wasteland

148 Fig. 5 : Relation between different indices (EI, SI, BI) in crop field and wasteland

149 Fig. 6 : Population structure of different nematode groups during various sampling times

150 A B 4 2.6 41 y = 2.04+2.60x 68.

.54 2 r = 0.918 10 60.

4 2.4 79 51.

5 M I .3 8 2 S I 4 43.

.25 16 2 35.

5 85 2.1 26. y = 2.00+2.36x r = 0.931

6 .54 2.0 18 0.2 3.7 7.2 10.7 14.2 17.8 21.3 0.2 3.7 7.2 10.7 14.2 17.8 21.3 % Dorylaims % Dorylaims

C D .65 9 72 3.2 y = 6.62-1.91x

.16 9 65 r = 0.913 3.0

.68 0 57 2.9

9 BI .1 0 50 2.7 P PI

.70 0 42 2.5

.22 1 y = 2.63+4.85x 35 2.3 r = 0.144 .73 1 27 2.1 0.2 3.7 7.2 10.7 14.2 17.8 21.3 5.8 12.0 18.2 24.4 30.5 36.7 42.9

% Dorylaims % Tylenchids

Fig.7: Relationships between different nematode groups and indices in crop field

151 A B 7 3.7 70 94.

1 3.5 35 85.

6 3.2 00 76.

M I .0 6 3 SI 6 66.

4 2.7 31 57.

9 2.4 y = 1.85+3.84x 96 y = 3.41+1.33x 47. r = 0.954 r = 0.898 3 2.2 62 38. 9.4 15.9 22.3 28.8 35.2 41.7 48.2 9.4 15.9 22.3 28.8 35.2 41.7 48.2

% Dorylaims % Dorylaims

C D 77 61 3. 47. y = 4.11-3.82x y = 5.41-8.23x 1 57 3.5 r = 0.869 41. r = 0.0.899

6 54 3.2 35.

00 .50 M I 3. 29

7 74 3.4 2. % Cephalobids 2

9 .44 2.4 17

3 .40 2.2 11 11.4 17.4 23.5 29.5 35.5 41.6 47.6 9.4 15.9 22.3 28.8 35.2 41.7 48.2

% Cephalobids % Dorylaims

Fig. 8: Relationships between different nematode groups and indices in wasteland

152

Discussion

Soil fauna have strong relationships with fundamental ecosystem processes such as decomposition and nutrient cycling, and interactions with the microbial community, plant growth and pedogenesis and thus can serve as useful indicators of ecosystem conditions (Parmellee, 1994; Auerswald et al., 1996;

Reddy et al., 1996; Anderson & Sparling, 1997). The nematode diversity of agroecosystems offers many possibilities for use as biological indicators of agricultural practices, soil characteristics and the degree of conservation of soils.

Whole nematode populations, represented by the structure of functional groups probably represent, in many cases, better indicators than those derived from any species in particular (Yeates & Bongers, 1999).

Soil nematodes have been found to regulate the bacterial and fungal populations and thus are intimately associated with the cycling of major nutrients in soils (Ingham et al., 1985) and a more positive view of the role of nematodes in soil processes has been adopted (Yeates, 1987). There are thus apparently significant possibilities for the use of nematode populations and diversity as indicators of overall soil condition. Nematode communities are sensitive to chemical and physical disturbances in ecosystem. These disturbances can alter nematode communities in qualitatively different ways (Fiscus & Neher, 2002). A higher percentage of dorylaims in the wasteland (27%) as compared to the crop field (12%) clearly indicates that the wasteland soil is less disturbed as may be expected. Cropping on the other hand always involves ploughing and/or tilling together with addition of fertilizers, organic matter and pesticides/weedicides.

The dorylaims appear to be susceptible to these activities as also shown by

Thomas (1978) and Sohlenius & Wasilewska (1984). Hence, the sensitivity of the

153 dorylaims is a good indicator of soil disturbance (Neher, 2001).

In this study Acrobeloides was the most abundant genus in crop field and confirms the work of Yeates & Bird (1994) and Gomes et al. (2002) where it was found that cephalobids were the most abundant bacterial feeders present in cropping systems.

Agro-ecosystems are generally characterized by periodic disturbances and tillage, cultivation, use of pesticides and fertilizers impede natural succession.

Although each of these disturbances have specific effects but mainly results in a decrease of diversity (Yeates & Bongers, 1999). Ploughing stimulates mineralization and results in increase in the number and dominance of opportunistic taxa. Pesticides influence soil biota directly or indirectly via plants.

It is generally accepted that undisturbed systems have more diverse communities of soil organisms (Kandji et al., 2001). Plots with more ground cover vegetation often support the most diverse assemblages of nematodes, possibly as a result of the greater heterogeneity of resources added through the return of residues and root exudates (Ou et al., 2005).

Bacteriovores in the crop fields showed two phases of population increase.

A small increase during December-January and a big increase during February-

March. One factor that may be responsible for the increase in the population of these nematodes in the early part is farmyard manure that was added to the fields before sowing. However the greater increase in the later (post-harvest) part of the study may also be due to organic matter. This becomes available because of decaying roots and rotting stubble after the harvest and could be the likely cause of this second peak. Organic amendments are known to increase the population of

154 the Ba1 group of nematodes and maintain them till the material is exhausted

(Bongers & Ferris, 1999; Porazinska et al., 1999). Manuring is also known to bring about a sudden increase in the population of bacterial feeders (Dmowska &

Kozlowska, 1988). The sharp decline of bacteriovorous nematodes during March-

April may also be due the organic matter; although this time acting perhaps differently. Depleted organic matter, of the decaying roots and stubble, could result in depleted bacterial populations and hence a reduced food source for the bacteriovores resulting in their decline. Bulluck et al., (2002) have shown that when food supply is exhausted bacteriovores populations also decline. Although temperature records were not maintained, there is a relatively big increase in maximum temperatures from February to April, and it may not be improper to speculate that this could lead to drying of the top soil and also a decline in nematode populations.

The herbivore population of the crop field varied little during the period of study except for a small peak in January. This coincides with the maturing of the crops and as such represents a period of an abundant food source brought about by the proliferated root system and seems to be the most likely cause of the peak.

Increase nutrient availability is known to increase herbivore populations through an enhanced food resource (Pattinson et al., 2004). Fertilizer application after sowing in October did not seem to affect nematodes as all trophic group populations remained relatively unchanged till December. Further, the peak of the herbivores coincided with peak or rising populations of the other groups. This contrasts with findings of Yeates (1982), Sohlenius & Bostrom (1986), Edwards

(1989) and Hoyvönen & Hühta (1989) who observed an increase in the plant

155 parasites and bacterial feeders after fertilizer application in cultivated soil or a decrease of fungal feeders and omnivores (Sohlenius & Wasilewska, 1984;

Sohlenius & Bostrom, 1986; Sohlenius, 1990).

In the wasteland, populations fluctuated little over most part of the year except from December to February when a small decline was followed by a peak in January in the case of bacteriovores, fungivores and omnivores. Predator populations remained at low levels throughout the year while the herbivores showed a peak in October. The increase of herbivores seems to be related to the grasses that grow in the wastelands after the rains. As winter sets in, this vegetation begins to wither and die and enriches the soil with organic matter that may be responsible for the peak populations of the bacteriovores, fungivores and the omnivores. In grasslands used by grazing animals, high populations of bacterial feeders were attributed to high level of food resource made available by addition of organic matter in the form of dung (Freckman et al., 1979).

Shannon’s diversity index (H’) reflects diversity of nematodes in an ecosystem. Higher values of H’ show highly diverse ecosystem while low values show the contrary. Háněl (1995) found H’ in crop fields to vary between 2.66-

2.83. In present work, the value of H’ was higher in crop field as compared to wastelands. This is in perfect agreement to earlier records where crop fields are found to be highly diverse in comparison to other ecosystems (Ferris et al., 2001,

Tomar et al., 2006). Nitrogenous fertilizers increases or decreases nematode abundance, as a consequence of the biomass production of plant root systems or increase in microbial activity (Berger et al., 1986; Sohlenius & Boström, 1986;

Sohlenius, 1990). Nematodes in crop field had higher generic and individual

156 abundance as compared to the nematodes in wasteland which is evident from the study of Shannon’s diversity index. The lower H′ values for wasteland which contrasts with the idea of Kandji et al. (2001) in all likelihood was because of lack of diversity in the food resources particularly of the herbivores.

The maturity index (MI) provides useful information on the direction of change within a particular habit. MI values for soil subjected to varying levels of disturbances range from less than 2.0 in nutrient enriched disturbed systems to

±4.0 in undisturbed, pristine environments (Bongers & Ferris, 1999). Agricultural practices, such as incorporating organic material (manure) into the soil stimulate microbial activity and provide resources for opportunistic nematode species, consequently, there is a rapid decrease in the MI followed by a gradual increase during subsequent succession (Bongers & Ferris, 1999). In the present study MI ranges from 2.1-2.59 in crop field and 2.36-3.66 in wasteland and is consistent with earlier observations (Háněl, 1994, 1998; Bongers, 2001; Tomar & Ahmad,

2009, Dechang et al., 2009). Higher MI values for wasteland could be expected as in undisturbed soil the ratio of higher functional guild species (dorylaims) to low functional guild species (rhabditidae, panagrolaimidae etc.) is much greater than in the crop field (27.2 - 31.8 vs 11.7 - 42.5). The highest value of MI in the crop field was observed in April, several weeks after harvesting. One key factor that may be responsible is the rapid decline of bacteriovores and fungivores accompanied by little or no change in the omnivore and predator populations. The

MI values for wasteland indicate it to be a more stable habitat, presumably because it is free from human intervention and with limited grazing. Here also the maximum MI value of 3.66 is most probably brought about by a decline in the

157 bacteriovore and fungivore population rather than in increase in the omnivore – predator population.

The PPI is very good indicator of plant parasitic nematode resources. Pate et al. (2000) estimated PPI values for crop fields at 2.3 while Neher & Campbell

(1994) recorded PPI as 2.82 and 2.51 in soybean plantations. The PPI values for present study in crop field agree with earlier records. The lower PPI values for wasteland is probably because of limited food resource and a lack of its variety.

The vegetation and the nematode population may have attained a state of equilibrium as can be expected in undisturbed areas. On the other hand, cropping provides varied and alternate sources of food to the plant parasites. PPI/MI is also very good indicator of enrichment (Bonger’s et al., 1997). In present work low

PPI/MI values for wasteland and high values for crop field indicates that more mature soil are less enriched as compared to manipulated soils. This is also borne out by the greater EI in cultivated soil as compared to the undisturbed wasteland.

Similar observations have also been made by Háněl (2004) and Tomar & Ahmad

(2009). The Nematode Channel Ratio (NCR) indicates a dominance of bacterial decomposition in both habitats but to varying degrees. Bacterial decomposition in the wasteland is of smaller order as compared to the crop field. However this contrasts with the observations of Bardgett and McAlister (1999) who argued that fungal pathways of decomposition dominate in natural ecosystem.

Food web indices like EI, SI, and BI may provide an excellent means for studying the stability of ecosystem, whether it is stressed, enriched or structured.

And provide information on the dynamics of the soil food web (Ferris et al.,

2001). Nematodes and other soil biota play an important role in releasing

158 nutrients from bacterial biomass for the uptake by the plant roots. These nematodes that respond first are enrichment opportunist and their biomass uptake continues as long as the bacterial activity is high (Bongers & Bongers, 1998).

The values for SI in crop field during present study were lower as compared to wastelands. The increase followed by a somewhat constant SI probably indicates a structured soil in a state of equilibrium where nematode populations fluctuate depending on the biotic and abiotic factors but not significantly affecting one another. It has been reported in earlier studies that generally in fallow soil and woodland the values of SI are higher which may due to high abundance of omnivores and predators suggesting a food web with more trophic linkages (Ferris & Matute, 2003). The higher the values of SI the more complex is the community structure. Fallow lands and forests have been reported to be more complex communities with reference to nematode in many studies

(Tomar & Ahmad, 2009). The values of SI for crop field fluctuated more erratically and seemed to be governed more by the population of omnivores, predators and possibly herbivores than by bacteriovores and fungivores. EI values were higher for crop field and lower in wastelands. The values for EI were lowest in October and highest being during September in wasteland, while for crop field the highest value of EI was recorded during October while the lowest value was observed at December, which incidently is the reverse for wasteland. Low values of EI reflect low abundance of Rhabditidae and high abundance of Cephalobidae, which can be well explained as the population of cephalobids is high compared to rhabditids in October for wasteland and December for crop field. EI is generally known to reflect availability of resources to the soil food web and response of

159 primary decomposers to the resources (Ferris et al., 2004). The basal index (BI) which is also a measure of enrichment show no significant changes over the sampling time, except for the month of December in crop field and June in wastelands.

Both in crop field and wasteland population of dorylaims show positive correlation with MI and SI (P<0.01). As dorylaims have cp values in range of 4-5 and their abundance plays major role in higher values of these indices. The incorporation of higher functional guilds for calculation of these indices results in high degree of positive correlation. BI shows a high degree of negative correlation

(P<0.01) with dorylaims in both crop field and wasteland. This clearly indicates the inverse relationship between dorylaimid and lower c-p value nematode guilds.

Cephalobids also show negative correlation with MI in wasteland (P<0.01) and crop field (NS). An unusual fact of almost no correlation between PPI and

Tylechids in both areas is perplexing and is strikingly different from the significant correlation reported by Háněl (1998) and Tomar & Ahmad (2009).

It may be concluded that nematode faunal analysis provides a good tool for diagnosis of the complexity and status of soil food webs (Ritz and Trudgill,

1999). The presence and abundance of specific taxa is an indicator of the complexity of the food web. Since related taxa, with similar morphological, anatomical and physiological attributed, have similar feeding habits, useful faunal analyses can be obtained by identification (Bongers & Ferris, 1999). As reported earlier the present study also confirms that nematodes are very good indicators of soil conditions. Although some contradictions have been found mainly the absence of correlation between PPI and tylenchids is highly surprising as most

160 studies in other parts of worlds as listed earlier, show significant correlation between these parameters. Decomposition pathways were predominantly bacterial in both the cropfield as well as wasteland, while crop field observations confirm to the studies of earlier workers, the wasteland observation is in contrast to this.

These contradictions are difficult to explain as various abiotic factors have not been taken into account, which can be a matter for further studies. Some factors like anthropogenic activities resulting in the loss of top soil, can have profound effect on the structure of the soil food web, which may severely limit its capacity to support optimal nutrient cycling, plant growth and other enriched functions. It is important to understand that indices developed from nematode faunal analysis are based on proportions of the fauna in various functional guilds. They provide an indication of the relative proportions of services and functions, but not of their magnitude. The biomass and abundance of organisms in various functional guilds is important in determining the magnitude of services. If biomass is also taken into account we can have better understanding of the resources available to soil food web organisms. The use of food web indices give better understanding of wastelands where human intervention and other activities are very limited throughout the year, but in case of crop field many factors play role in defining the condition of soil and population dynamics of nematodes, therefore a generalized study is not possible for food webs of crop fields.

161

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