THE , DISTRIBUTION, AND DEVELOPMENTAL STAGES OF WATER COLLECTED IN CENTRAL AND NORTH CENTRAL OHIO

DISSERTATION Presented In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By ROBERT MERRILL CROWELL, A.B., M.A.

The Ohio State University 1957

Approved by:

Adviser Department of Zoology and Entomology ACKNOWLEDGMENTS

The writer wishes to express his thanks to those persons who have facilitated the pursuit of this project. I am especially grateful to the several Individuals, students, and colleagues who have contributed specimens for use in the study. The cooperation of members of the staff of the Chicago Natural History Museum, in making available Iden­ tified material from the Huth Marshall Collection, is acknowledged with appreciation. I should like to thank Dr. C. B. Philip and the editors of The Scientific Monthly for permission to quote the passage included in the epilogue. Thanks are due also to Hand McNally and Company for permission to reproduce the copyrighted map of Ohio, Figure 18. The following sources have supplied funds through grants-in-aid which have assisted in financing various phases of the project: The Ohio Academy of Science, The William H. Wilson Awards (College of Wooster), and the Professional Development Fund (St. Lawrence University, Canton, N. Y.). This assistance Is deeply appreciated. il ill Finally, I should like to acknowledge with thanks the guidance and counsel of Dr. Carl E. Venard in the course of this work. TABLE OF CONTENTS

CHAPTER - PAGE INTRODUCTION ...... 1 I. GENERAL SYSTEMATICS OF THE WATER MITES AND REVIEW OF THE LITERATURE...... 3 II. GENERAL CHARACTERISTICS OF THE WATER MITES . 10 III. THE LIFE CYCLE OF WATER M I T E S ...... 22 IV. THE OCCURRENCE OF WATER MITES ON . . 30 V. COLLECTION AND PREPARATION OF MATERIALS . . . 39 VI. SYSTEMATIC RECORD OF OHIO WATER MITES .... 53 - Family Hydrachnidae ...... 53

Family ...... 67 Family Thyasidae ...... 7b Family ...... 81 Family Hydrodromidae...... 91 Family Lebertiidae ...... 96 Family ...... 100 Family ...... 107 Family ...... 110

iv TABLE OP CONTENTS (Continued)

Family ...... Ill;

Family Arrenuridae ...... 138 Unassignable material...... li|.l

Additional r e c o r d s ...... H 4.I

SUMMARY...... IIOj. LITERATURE C I T E D ...... 1^$ ILLUSTRATIONS ...... 1$5 EPILOGUE ...... 18 k AUTOBIOGRAPHY...... 185

v LIST OF TABLES

TABLE PAGE I. Summary of Infestation of Insects with Water Mites (Gibraltar Island and Vicinity. June

July, 195^4-)...... 33

vi LIST OP ILLUSTRATIONS

FIGURE PAGE

1•i. _ 17. Structural characteristics of water mites ...... 157 18. Map of Ohio showing distribution of

collections ...... 159 19 - 22. Collecting equipment and techniques 159 23. Specimen of Ranatra sp. heavily para­ sitized by Hydrachna magniscutata 159 2k - 38. Hydrachna magnlflcutata...... 162

39 - ip.. H. rotunda ...... 165 k2 - 56. H. baculcscu^ata , ...... 165 .97 - 76. extendens ...... 169 77 - 89. Thyas stolli ...... 169 90 - 97. ruber ...... 172 98 - 105. H. waynensis ...... 172 106 - 115. despiciens ...... 175 116 - 119. porosa ...... 175 120 - 122. indistincta ...... 175 123 “ 125. T. bittikoferae ...... 175 LIST OP ILLUSTRATIONS (Continued)

126 - 131. Limneaia u n d u l a t a ...... 178

132 - 136. Hygrobatea longlpalpis...... 1?8 137 - 114.1 . Tiphya torria var. amerlcanua . . . 178 lij.2 - l£0. Piona rotunda ...... 1®1 l£l - 159. P. reighardl...... * • * 1®1 160 - 167. P. naplo ...... 1®3 .168. Arrenurus latlcornis ...... 183

169 - 170. A. m a r a h a l l a e ...... 183

viii INTRODUCTION

The water mites are a little-known group of arthro­ pods of wide occurrence. They may be found In almost all types of aquatic habitats. As adults they are most abundant In vernal ponds and in the littoral zone of larger bodies of water. They may also be found in rivers and streams and along rubble beaches. As larvae they are often observed parasitizing aquatic and semi-aquatic Insects. The lack of knowledge about the group is sometimes accounted for by reference to their small size and obscure habits. However, they exceed most of the protozoa and many of the trematodes in size and are certainly more obvious than the Individuals of both of these groups which are much better known. Their lack of economic importance has been cited as an explanation of the absence of information about them. A demonstration by Uchida and Miyazaki (1935) of the water mites as a potential biologi­ cal control agent of anophellne mosquitoes indicates that they may have unrecognized economic significance. The occurrence of water mites as parasites of noxious insects suggests possibilities for research and investigation of problems in basic biology. Whatever the explanation for the paucity of Infor- mation may be, it is true that only six American investi­ gators have published on the water mites within the past ten years. Not since Miller's Introductory Study of the Acarlna, or Mites, of Ohio in 1925 has there been a paper indicating the hydracarinid fauna of Ohio. Miller's listings included nine species of water mites. The writer's aim in the present investigation has

been twofold. First, I have endeavored to expand the knowledge of the Ohio fauna through collection and identi­ fication of water mites in the central and north central

regions of the state. Secondly, I have attempted to present general and systematic information about the group in such a manner that it can be utilized by the general biologist in identifying water mites which he may collect. Anatomical structure of mites and methods of collection and handling are considered in detail subse­ quently. Determinations have been made by the writer, based on comparisons with Identified material in the writer's collection or material loaned by the Chicago Natural History Museum. Chapters I to V inclusive cover various phases of general information about water mites. Chapter VI pre­ sents, In systematic order, descriptions and data con­ cerning the 19 species identified. Four of these are new species. Taxonomic features of all species which have been identified are illustrated. CHAPTER I

GENERAL SYSTEMATICS OP THE WATER MITES AND REVIEW OP THE LITERATURE

The water mites are an. ecological grouping of Acarina which appear to represent several phyletic lines. American authors have generally referred to them as the Hydracarina. European authors frequently use the term Hydrachnellae for this group. In such usages one must keep in mind the fact that neither of these terms repre­ sent taxonomic categories, although Pennak (1953) gives the term Hydracarina ordinal rank. Viets (1956) lists 2817 species of Hydrachnellae plus sub-species, species inquirendae and those of incertae sedis. Mitchell (1954)* whose check list represents the only modern attempt to examine the extent of work on North American water mites, lists 291 Species which have been reported from this continent. The water mites have generally been considered among the prostigmatid mites of the sub-order Trombidi- formes (see Viets, 1936:40)• However tracheal stigmata have been demonstated In only a few species, and critical study of tracheal systems is needed to aid in establishing

3 k •------this relationship. Until such information is available such relationship can be only speculation. Attempts to arrange the world fauna in a phylo­ genetic classification have not been entirely satisfactory, and the schemes in current use remain largely artificial. Modern classification of the water mites has evolved over a period of nearly 200 years, although the first authentic reference to a water is slightly older than that. According to Soar and Williamson (1925: 1) in 1730 Johann Leonhard Frisch described and illustrated “a little red water-spider which obtains nutriment by sucking the body of the Wasserlaus.n Seven years later, in 1737, Boer- haave's publication of Jan Swammerdam's manuscripts ’•showed that he had observed a water scorpion (Nepa) with what looked like an egg attached, but which on being opened showed a spider-like creature (nymph)” (Soar and Williamson, loc. cit.). It appears that 0. F. Mflller (1776)> in a paper not seen by the writer, attempted the first organization of the known species (then numbering I4.0 ) into groups. His grouping, based on the number of eyes, is outlined by Soar and Williamson (1925: 36). Originally he arranged the mites into two groups: Oculis duobus and Oculis pluribus. Subsequently he divided them into: a. Oculis binis, subdivided into (1) Caudatae, (2) Furcatae, 5 (3) Postice pilosae, and (4) glabrae; b. Oculis quator; c. Oculis sex. About 1800 Latreille published a series of papers in which he assigned generic names to the known water mites and in 1802 grouped them in one family which he named Hydrachnellae (Soar and Williamson, loc. cit. and Viets 1936: 1+1). The family, as arranged by Latreille was divided into two families by Leach in 1815 (Wolcott, 1905: 175)* One family, containing the single Eylais, he named Eylaides- The two remaining genera, Hydrachna and Llmno- chares, he placed in the family Hydrachnides, Koch's synopsis of classification divided the into four sections, two of which were Wasser- milben and Sumpfmilben (Soar and Williamson, 1925:37)* The water mites he arranged in two families, viz. Hygro- batides (stream mites) and Hydrachnides (pond mites). The former family included ten genera: Atax (now TTnionicola) Nesaea (now Piona in part) Plona Hygrobates Hydrachoreutes Arrenurus Atractides Acercus (now ) Diplodontus Marica (now Oxus) The latter family included five genera: 6

Llmnesla Hydrachna Sydryphantes Hydrodroma Eylais To the swamp mites he apparently did not give a family designation but listed two modern genera of water mites, Limnochares and Thyas, and two genera now considered with the terrestrial mites. Between l8ij£ and 1893 there were two notable attempts to regroup the water mites. Kramer (1877* cited in Wolcott, 1905:176) divided the water mites into four families, based on characteristics of the chelicerae. These families were Hydrachnidae, Eylaidae, Hygrobatidae, and Limnocharidae. In 1881 Haller (cited in Soar and Williamson, 1925:37) gave sub-ordinal rank to the Hydrach­ nidae and divided them into two families based on the position of the eyes: the Medioculatae, including the genera Limnochares and Eylais, and the Lateroculatae, including all other known genera. In 1893 Kramer made the first attempt to use char­ acteristics other than adult morphology to arrange the water mites in a systematic scheme (Wolcott, loe. cit.). Having recognized three larval types among the water mites he made these the basis for three families: Hydrachnidae, Hygrobatidae, and Eylaidae. With a fourth family, Trom- bidildae, he set up the order . Thor in 1900 divided the group into Ilf families.

Unfortunately the basis on which assignment of genera to families was made is not discussed (Wolcott, 1905il77).

Plersig (1901) listed £7 genera of freshwater mite3 which he placed in the single family Hydrachnidae. Sub­ family divisions were not indicated.

In the same year Wolcott (1901:113) presented the following scheme to indicate the relationships of the water mites:

Phylum - Arthropoda, Glass - Arachnoidea, Order - Aoarlna, Sub-order - Prostigmata, Tribe I - Trombidini, Tribe II - Hydracarinl, Fam. 1 - Hydrachnidae, Fan. 2 - Limnocharidae, Sub.-fam. 1 - Limnocharinae, Sub.-fam. 2 - Eylainae, Sub,-fam. 3 - Hydryphantinae, Fam. 3 - Hygrobatidae, Sub.-f amilies?

Subsequently the same author (Wolcott, 190^:177-178) recog­ nized five families, based on larval characteristics.

These he listed as Hydrachnidae, Limnocharidae, Hydryphan- tidae, Eylaidae,and Hygrobatidae. As a sixth family, based on imaginal characteristics, he included the family Pierslgiidae.

Subsequent listings have represented modifications of the scheme presented by Thor in 1900, expanded by the discovery and addition of new forms. The works of Viets (193& arid 19.66) end Lundblad (1911) represent the most useful of modern systematic listings of the water mites. The 231? species listed by Viets (1966) are arranged in 1|6 families. This represents an increase of 1<6 families over the listing in Viets (1936) and an increase of eight families over the number listed by Lundblad (19i|l). While part of the increase results from reassignment of genera, most can be accounted for by the discovery of new forms. Systematic schemes in current use are admittedly artificial. It seems likely that the similarity of adult characteristics used in grouping the water mites could as readily result from convergent evolution as from diver­ gence of ancestral stocks. The relative constancy of an aquatic environment would seem more conducive to conver­ gence than to divergence. The schemes of Kramer and Wolcott, relating the water mites on the basis of larval morphology, have not been investigated further. This probably results from the fact that relatively few larvae are known with cer­ tainty, and these few are not well known. With the water mites, as in many other groups, there is need for rearing specimens which will relate immature and adult forms. The literature on the water mites, especially on the American fauna, is widely scattered in many journals. 9 The papers of Koenike (1999 and 1912) and Wolcott (1901-

1909) represent the earliest comprehensive works on

American water mites. The papers of Marshall (1903-19l|6)

are indispensable in the Identification of mites of the middle west.

Recent papers by Cook (195^-1955) and Lavers (19i|5) are necessary for determinations in the large gen- us Arrenurus. Mitchell's check list (195k) is an invalu­ able aid in the identification of species previously re­ ported. Only one paper lists species of water mites found In Ohio (Miller, 1925). His paper lists eight spe­ cies from Buckeye Lake and one from Cedar Point. Three of these species have been collected In the present sur­ vey. To the specialist in the group the keys of Viets (1936) and his bibliography, catalog, and nomenclator (1955-96) are of inestimable value. A translation of Viets* key is presented In Baker and Wharton (1952). For the non-specialist Wolcott's key in Ward and Whipple (1918) and the key of Pennak (1953) will aid in deter­ mining the genera commonly encountered. The Ray Society monograph of Soar and Williamson (1925-1929) Is a source of valuable general information and natural history of the group. Two papers of note have appeared concerning the Internal anatomy of water mites (Bader 1939 and 195^)• CHAPTER II

GENERAL CHARACTERISTICS OF THE WATER MITES

The Hydracarina, although exhibiting a wide range of variation within the group, can readily he differentiated from most other mites which are likely to be encountered

In fresh water ponds and streams. Oribatolds, of which several species may occur crawling on submerged pond de­ bris, generally possess sensillae arising from the anterior margin of the dorsum and exhibit a more extensive sclero- tizatlon. They are generally of a dark brown, glabrous appearance. The Hydracarina lack these characteristics.

Halacarids, of which a very few genera are represented in fresh water, have legs three and four directed posteriorly.

In the Hydracarina these legs are directed laterally.

The body of a water mite Is generally globular to ovoid In shape, though Individuals of several genera may be somewhat dorsoventrally depressed. Most of the species common to this area vary only slightly from a range of one to two millimeters In longest dimension, although gravid hydrachnids collected in Ashland County measured up to four millimeters In length and three millimeters in breadth. 10 The oommonQ3 t colors for living mites are shades of red and reddish orange, but green, blue, and brown are frequently observed. The color may vary within a species;

this has been accounted for on the basis of recency of feeding and material ingested. In certain cases the legs may exhibit a different color than the body. Often promi­ nent color patterns appear when a mite is observed in dorsal view. In certain instances these patterns appear to represent the distribution of visceral organs and materials contained therein. In other cases, e.g. in certain arrenuri and axonopsids, the patterns result from coloration of dorsal and ventral plates. It is probable that tooth of these factors contribute to the observed pattern. In the descriptions which follow, observations on coloration and color variations will be indicated for those species where information is available.

Orientation of legs and types of locomotor activity present means of recognizing water mites in the field.

Adult mites possess four pairs of legs, arising from the anterior half of the ventral surface. These are directed anteriorly or antero-laterally at their bases. The legs may be generously or sparsely equipped with setae. Bottom dwelling forms, such as those found in streams and current- swept rubble beaches, typically possess very few setae which are reduced in size. Swimming forms, such as those found in lotic waters typically possess many elongate se­ tae, called swimming hairs, often arranged in vanes along the leg segments. The number, size, and orientation of leg setae is reflected in the locomotor activity of water raites, and furnishes a ready means of distinguishing them from other , in the field, with only a little practice. In most water mites the integument is thin or leathery and the body soft. Many forms, however, show varying degrees of sclerotlzation, some being nearly com­ pletely enclosed in dorsal and ventral plates. Two ex­ tremes of sclerotlzation are represented in the present survey by the very soft bodied hydrachnids and limnesi- Ids, and the extensively plated arrenurrlds and lebertlids. Various types of dorsal plates or shields may be present. The genera Hydrachna and Hydryphantes illus­ trate types of plates which may occur (Pigs. 1-3)* In the family Thyasidae the pattern of plates and glandular- ia is of taxonomic utility (Figs. 77 and Bip). Numerous epidermal glands are present in many water mites. The in­ dividual plates and glands may be associated with special­ ized setae. This chaetotaxy is likewise useful in making taxonomic distinctions. Typically the eyes of water mites are four in num­ ber. The two eyes of each side are generally situated 13 near one another on a single sclerotized plate. The eyes

may be close together on the plate, or there may be a non-

sclerotized space separating them. The paired plates are

located on the dorsum near the antero-lateral margin of

the body. There are numerous exceptions to this pattern.

Notable among the exceptions is the genus Eylais In which

the eyes are situated on ocular plates (Pig. U) joined by

a sclerotized bridge, the whole presenting the appearance

of a pair of spectacles (the "Augenbrille" of Viets and

others}. Some species of Hydrachna and Hydryphanfces pre­

sent another exception, possessing in addition to later­

al eyes an unpaired median ocellus or "frontal organ" (Pigs. 1-3).

For descriptive purposes, the body of a mite has

been arbitrarily divided Into regions according to a

scheme followed by Vitzthum (19ij.O) and reproduced by Baker and Wharton (195>2). This scheme is adapted to the body of a water mite in Figure 1?. The anterior region which bears the mouth and its associated appendages Is called the gnathosoma. The remainder of the body is referred to as the idiosoma. The leg bearing region of the idiosoma is called the podosoma. Legs I and II are borne on the propodosoma; legs III and IV are borne on the metapedosoma.

The idiosoma posterior to the metapodosoma is known as the opisthosoma. All of the body anterior to the opisthosoma Is the prosoma, Gnathosoma and propodosoma are collective­ ly referred to as the proterosomaj metapodosoma and opis­ thosoma are referred to as the hysterosoma.

In the water mites the gnathosoma is a distinct region, but the idiosoma is not apparently segemented.

Movement of the gnathosoma Is generally quite restricted in the water mites. However, some species, notably in the genus Hydrachna, possess a gnathosoma which mgy be pro­ truded nearly half the length of the body.

In most older works on the water mites and in some recent works the gnathosoma is referred to as the maxil­ lary organ or as the capitulum. The first term seems especially inappropriate and should be avoided since max­ illae are considered to be absent in the Acarina. Capit­ ulum is perhaps less objectionable. However the structure is not conqcarable to the head of other arthropods, since it bears only the mouth and mouth parts and lacks sense organs and nerve ganglia usually found in the head. The venter of the gnathosoma is protected by a plate, generally shield-shaped. This has been called the maxlllary-shield but for the reason stated above, Is here termed the gnathosomal plate or shield.

Dorsally, near the base of the gnathosoma and obscured by the bases of the gnathosomal appendages, there is situated a single pair of minute stigmata. These are 15 difficult to see because of their size and location, and can be observed only in favorably dissected preparations (Pig. 5). Stigmata have not been demonstrated in all species. Appendages of the gnathosoma are four in number, the paired chelicerae and pedipalpi. The chelicerae have been called mandibles by most early workers, and the pedi- palps are generally referred to simply as palps. The chelicerae are the most anterior acarinid appendages. Those of the water mites are non-chelate, consisting of a single movable digit. Generally they are sickle-shaped, but in some cases they are saber- or dagger­ like (Pigs. 6, 7)* The medial surface of the distal seg­ ment is often serrate. In all cases they are small and inconspicuous. They are retracted except during feeding, when they are utilized as a cutting tool. At rest they are enclosed in an anteriorly projecting rostrum, in certain forms (Pig. 8). The modifications of the pedipalpi, and their chaetotaxy, have been used extensively in making taxonomic separations. The palps arise at the antero-lateral angles of the gnathosomal plate. They are composed of five seg­ ments (Pig. 9). The segments are called (beginning proxim- ally) the trochanter (P-l), femur (P-2), genu (P-3) (patel­ la of Viets), tibia (P-l}.), and tarsus (P-5) • The coxae 16 of more primitive arachnid appendages are apparently insensibly fused with the gnathosoma, probably making up the gnathosomal shield. Any of these podomeres may bear peglike projections or variously modified setae. The seg­ ments may be greatly enlarged or much reduced. In some forms the palpal tibia and tarsus form together a shear- llke structure (Fig. 10). The palpi are used variously by the mite in food taking, attachment, mating and ovi- position. Prominent features of the idiosoma are the ventral eplmera. They are expanded, much modified coxal plates of the locomotor appendages. Their position, shape and chaetotaxy present useful taxonomic features. Adjacent epimera may be widely separated, joined with a prominent suture, or indistinguishably fused. Epimera I and II and epimera III and IV are usually fused in varying degrees, with considerable non-sclerotized Integument separating the groups. There may be non-sclerotized integument along the mid-ventral line, or the epimera of the two sides may meet in various degrees of fusion. Habeeb (1955) has expressed the various groupings and fusions in the form of "structural formulae1' which the present writer finds of doubtful utility. The epimera may be decorated with setae. Their surface may present sculpturing in the form of pits, granulations, ridges, or papillae. 17 The podosomal appendages are eight in number In adult water mites, the four pairs of legs showing structu­ ral specializations facilitating swimming, clinging, and in some cases mating. The legs consist of six movable podomeres (Fig. 11). The proximal segment is the trochan­ ter. Proceeding distally the podomeres are the basifemur, telofemur, genu (patella of Viets), tibia, and tarsus. These are referred to in descriptive literature by Arabic numbers, with Roman numerals referring to the leg. Thus the designation "Ill-b'1 refers to the tarsus of the third leg. As indicated previously the setal equipment of the legs varies with the habitat of the species. Spines, pegs, and notches of various sorts may be present. Typically the tarsi possess two terminal claws. In some genera there is sexual dimorphism in the structure of certain leg seg­ ments. For example, in the genus Piona, leg segment IV-i{. possesses a distinct notch which facilitates clasping during mating, and segment III-6 is an expanded, somewhat flattened podomere utilized as an intromittent organ (Figs. 12, 13). An additional modification is illustrated by the peculiar angle formed between segments IV-5 and IV- 6 of Forella sp. (Fig. Ilf.). In nearly all species of water mites the external genitalia present characteristics which are of taxonomic 18 utility. The genital field (Fig* 15) is situated on the ventral surface between or behind the posterior epimera. In some forms, e.g. Tlphya {Figs. 137 and 138), it occupies a position on the posterior margin of the venter where it extends vertically toward the dorsum. The genital orifice is a longitudinal slitlike aperture in the mid-ventral line. Frequently there are anterior and posterior sickle-shaped supporting sclerites imbedded in the Integument. Flanking the orifice are genital plates, usually bearing genital suckers or aceta- bula which may be cuplike or knoblike, sessile or pedi­ cellate. There may be more or less movable sclerotized flaps or valves which cover and enclose the ace tabula and orifice (e.g. Lebertia; Fig. 116). Males of some genera exhibit a highly specialized, sclerotized aedeagus. One form of this structure is repre­ sented by the anchor-shaped aedeagus of males of Plona (Fig. 16). There may also be present on the ventral surface (Fig. 17)# located posterior to the genital field, a sclerite which has been termed the anal-plate. This bears an opening which has been called the anal-pore. This most certainly is not associated with the digestive tract which ends in one or more blind cecal pouches. The pore does, however, connect with the excretory organ and 19 therefore functions in the release of excretory material.

More appropriately then, these structures will here be

referred to as the excretory plate and excretory pore.

The immature stages of water mites differ in sev­

eral features from the adult forms on which the previous

remarks have been based. The specific features of these

stages will be considered in the systematic portion of

this report, but several generalizations can be made here.

Nymphs generally present the same body shape and

form as adults of the same species, but they are usually

slightly smaller in size. Often they are of paler color

than the adults. Sclerotization is frequently reduced in

comparison to the adult forms. Arrangement of the eyes

is generally like that of adults.

There are six pairs of appendages in nymphs--chell- cerae, palps, and four pairs of legs. They do not differ from adults in number of segments, but specializations in the number and orientation of setae, pegs, and spines may vary.

The epimera generally present the same form and arrangement in nymphs as in adults. Setal patterns of the epimera differ somewhat, and in general there are fewer setae in nymphs than in adults. However, it is often possible to recognize, by position, certain setae which are retained in the adult and others which are 20

wanting in the adult. The provisional genitalia are less

extensively developed than the genitalia of the adult.

Genital plates are smaller and usually contain fewer ace-

tabula. There is no genital orifice.

An excretory pore may be present, but frequently

it is not situated on a plate.

Larval water mites differ notably from nymphs and

adults of the same species. They are, of course, much the

smallest of the three stages. They are generally less

globular and more ovoid in outline than subsequent stages

and are typically flattened. In species represented in

this study, the larvae are more extensively plated than

later stages.

Coupled with their parasitic feeding habits, the

gnathosoma of larvae makes up a greater proportion of the

total body than in adults and nymphs. The well-developed

chelicerae are used for piercing and holding. The pedi-

palpi, at least in certain species, have prominent setae

which are presumably sensory in function.

The podosomal appendages of the larvae consist of

three pairs of legs, in contrast to the four pairs in

nymphs and adults. These present segmentation which

differs from nymphs and adults In that the legs of most

larvae consist of five podomeres, while those of nymphs

and adults consist of six podomeres. The legs of Thyas larvae are six-segmented. 21 There are three pairs of ventral epimera; differen­ tiation of the third and fourth epimera of subsequent stages has not occurred in the larva. The epimera may possess fewer setae than in the later stages. The genital field bears little resemblance to that of stages which follow. There is no genital orifice. O-enital plates and acetabula are reduced or wanting. An excretory pore is present in some species but has not been observed in others. CHAPTER III

THE LIFE CYCLE OF WATER MITES

In a general way the life cycle of water mites is known. It consists typically of four stages: egg* larva, nymph, and adult. A deutovura, nymphochrysalis, and imagochrysalis precedes the larval, nymphal, and adult stages respectively. In many species the larva is parasitic, while the nymph and adult are free liv­ ing, predaceous individuals. There are numerous devia­ tions from this typical plan, some of which will be considered subsequently. The eggs of water mites are usually reddish-orange in color, though colorless eggs are known. Variation may be noted in the color of eggs of a single species. For example eggs of Piona rotunda observed in the course of this study varied from colorless to tan and pale orange. Eggs may be laid singly, in small clutches, or in masses of up to lj.00 or more eggs. Eggs may be individual­ ly encapsulated in a gelatinous matrix (Fig. 105) or they may be arranged In capsules containing two or four eggs (Fig. 76). In still other cases the entire egg mass may be covered with a gelatinous secretion. The eggs may be 22 23 rather irregularly arranged as In Eylals, or they may be in short, nearly straight ribbons as in some pionas. The egg masses may be attached to submerged stones, sticks, and aquatic plants. Leaves of Sphagnum and Myr1ophy1lum are frequent substrates on which mites deposit their eggs. In the present study mites kept in laboratory rearing dishes have generally affixed their eggs to the sides of the dishes, in the absence of natural objects which might otherwise be utilized. Some water mites deposit their eggs in cavities made in plant tissues (Soar and Williamson, 1925:10). According to Marshall (19i}.6:352) Hydrachna magniscutata deposits its eggs in galleries made in Potamogeton rlchardsonii. In the pre­ sent study this species was observed to scatter its eggs singly and unattached about the rearing dish, there being no plant materials provided. The eggs of water mites hatch in a length of time which varies from less than a week to about six weeks. The majority of Ohio species for which data are available hatch in two to three weeks following deposition. It is quite likely that under natrual conditions temperature is an important factor influencing hatching time. Eggs of Hydryphantes ruber which I kept In a refrigerator for seven days and then returned to room temperature took 20 days to hatch as compared to a portion of the same egg masb which was kept at room temperature and hatched in 12 days. 2k At the end of its period of embryonic development a six-legged larva emerges from the egg capsule. The pre­ cise manner of emergence has been noted in only a few in­ stances. Soar and Williamson (1925illj.-l£) have noted that some larvae rupture the egg shell by pressure (e.g. Leber- tia) while others utilize spines on the dorsal surface in accomplishing this (e.g. Thyas). The writer has observed that later hatching larvae in an egg mass will utilize the exit hole made by an earlier hatching individual in escap­ ing from the gelatinous capsule. In most species the gnathosomal appendages of the larva are well-developed, coupled with their parasitic feeding habit. The podosomal appendages are five-seg­ mented except in certain species of Thyas where they are six-segmented (Soar and Williamson, 192^:1^). After a short period of free existence the larvae of most water mites attach to aquatic or semi-aquatic insects during which period nutriment is obtained from the host. The occurrence of water mites on insects will be considered subsequently (Chap. IV). After a feeding period of variable extent the larva enters a nymphochrysalid stage during which metamorphosis begins. According to observations of several investiga­ tors, as feeding ceases the larva shrinks within Its exo­ skeleton and in a short time the developing nymph can be 25 seen within. In the present study this has been noted for Hydrachna magniscutata (Pig. 37). The mechanics of emergence of the nymph from Its nymphochrysalis are not noted in the literature. Soar and Williamson (1925s27) suggest that vigorous activity of the legs is responsible. In the case of Hydrachna magniscu- tata observed by the writer the nymph emerged from a transverse slit which developed in the larval skin about 2/3 of the body length from the anterior end. The larval skin remained attached to the host . The nymphal existence of most water mites Is a free living, predaceous period. The nymph is generally larger than the larva, and usually smaller than the adult. Like adults the nymphs possess four pairs of six-segmented legs. The genital field of nymphs exhibits fewer acetabula and less extensive plates than that of adults of the same species. Typically there is no genital orifice. The genital apparatus of nymphs has been referred to In the literature as the "provisional genitalia." Sexual dimorphism of nymphal stages has been re­ corded for Thyas barbigera and Unionicola aouleata in

Viets (1936:I}.77 and 14.8 3 ). It is recorded for two species of Hydrachna In this report. An imagochrysalis stage occurs following the free living nymphal existence. This is ordinarily passed 26 attached to plant tissues or in some obscure, secluded niche. Imagochrysalids of Eylals extenders attached to sprigs of Myrlophyllum by curling of the legs around the plant have been collected by the writer. A new species of Hydrachna is here recorded in which attachment of the imagochrysalis to plant tissue is accomplished by the gnathosomal appendages (Figs. 60 and 56). Imagochrysalids Lebertla porosa have been removed from caddis cases collected on a rubble beach at Middle Bass Island in Lake Erie. In those species observed by the writer emergence of the adult from the nymphochrysalis has been afforded by a general breakdown of the nymphal skin. No special sutures or manipulations have been noted. Imamura (1952b: 14.50) has recorded the fact that an adult of Arrenurus soochowensis was observed to cast off a molted skin. This appears to be the only record of molting in an adult water mite. The arrenuri present con­ siderable variation in body form, and Imamura1s observa­ tion supports his suggestion that there may be a series of imaginal molts accompanying the change of form. The adults of water mites are typically free living and predaceous. The sexes are separate and sexual dimor­ phism is apparent in the external genitalia and epidermal sclerites of most species. In some species sex differ­ ences in body form are extreme. 27 The length of life of adults is not known with

certainty hut the adult is assumed to be the over-winter­

ing stage in most species. To the writer*s knowledge this

statement has not been supported by field observations.

The longest survival time authenticated by the writer is

in the case of a new species of Hydryphantes of which the

writer kept a specimen under refrigeration from its collec­

tion on 16 May, 1954* until 15 March, 1955, and which sur­ vived until 15 April, 1955, after being removed from the

refrigerator. Pennak (1953:477) states a widely held assumption that some genera are capable of withstanding periods of drought by being buried in wet mud and debris of the sub­ strate. There appears to be no positive demonstration of this in the literature. Numerous attempts by the writer to collect mites from such habitats have been unsuccessful. The various species of water mites show a wide variety of copulatory patterns. A very specialized be­ havioral pattern is exemplified by Arranimus globator, in which the male carries the female about on his cauda, depositing spermatophores on the substrate as he walks, and subsequently lowering the female onto the spermato­ phores in such a manner that the sperm packet is placed within the genital orifice (Viets 1936:4-05)• Marshall (1929b:401“402) has described a more common pattern as 28 exemplified by Fiona amerioana. In this species the ven­ tral surfaces of the copulating pair are apposed, with legs XV of the male hooked over legs I of the female. Male legs III are utilized in the transfer of sperm masses from the genital orifice of the male to the genital orifice of the female. The mating behavior of most species has not been observed. A well-developed aedeagus is present in males of many species; its function in oopulation is not known. Exceptions to the general pattern of the life cycle outlined above are found in many species of water mites, and only a few of these can be considered here. Piersig (cited in Soar and Williamson, 1925>s2ij.) states that the eggs of Brachypoda versicolor are concealed singly among water plants. These larvae are non-parasitic and attach to aquatic vegetation during the nymphochrysalid stage. The same author (oj>. cit.:23) Indicates that the larval existence of Llmneaia undulata is passed under the gelati­ nous layer which covers the eggs. L. undulata has been collected in several locations in Ohio, but developmental observations have not been made. In still another species, Piona rotunda, Piersig states that the larval stage is suppressed, the nymph hatching directly from the egg. This has been supported by my observations of this species in Ohio. 29 My observations of Thyas stolll indicate that this species lays eggs which hatch into typical larvae as well as eggs which hatch into typical nymphs. The conditions effecting this difference are not known. While most nymphs are free living, as stated above, the nymphs of Hydrachna magniscutata have been observed by the writer feeding on a water scorpion. According to Soar and Williamson (1925i17) nymphs of Limnochares have been obtained from water striders. Many species of Unlonicola are found in all stages of their life cycle in association with pelecypod mollusks and occasionally in gastropods. Whether or not the association between the nymphs and adults and their host is one of true parasitism is a question beyond the scope of this survey. They have generally been considered para­ sitic (Viets and Plate, 195>lj.; Mitchell and Pitohford,

1953). CHAPTER IV

THE OCCURRENCE OF WATER MITES ON INSECTS

Moat of the work which has been done with the

Hydracarina up to the present time has been concerned with the systematic and limnological aspectB of the adult, free living stages. In the preceding chapter it was pointed out that typically the larvae of the water mites are para­ sitic on aquatic and semi-aquatic insects, although little information is available about species of mites and insects involved. Numerous isolated observations of larval mites on insects have been reported by Soar and Williamson (1925: 15-26) and by Viets (1936:1+88-506) as well as by other authors. The papers of Munchberg, published between 1935 and the present, and those of Imamura, appearing between 1950 and 1952, have been more specific in identifying the organisms involved.

The physiological relationships of water mites and their hosts have been considered by Marshall and Staley

(1929) and more recently by Wharton (1951+) • The former authors reported unbranched stylostomes, or feeding tubes, in mosquitoes as a result of parasitism by larvae they 30 31 Identified as Lebertia taulnsignata. They considered the tubes to be chitinous and of host origin. Based on his observations of Trombidium sp. on the common firefly Photurls pennsylvanica, Wharton has concluded that the stylostome is not chitinous, since its staining reaction is different than that of host and mite integument (Whar­ ton 195^i2i|.5). He suggests that the stylostome may be formed as a result of the precipitation of the mite*s salivary secretion by the host tissues, solidification occurring at the interface between mite saliva and Insect blood. Host-parasite surveys attempting to determine the degree of infestation have been reported by Uchida and Miyazaki (1935) and by the writer (Crowell, 1950). The former report involves an Asiatic species of Arrenurus parasitizing anopheline mosquitoes and Indicates an infestation rate of 58.7#. The latter report includes 12 families of insects collected in Durham County, North Carolina, showing an infestation rate of 0.9#. The information in the present chapter is based primarily on the results of a survey of Insects collected by the writer on and near Gibraltar Island in western Lake Erie. These collections were made between 25 June and 16 July, 1951}-• This information has been previously summer- 32 ized in an unpublished project report submitted to Dr. N. W. Britt at the Stone Institute Laboratory, Ohio State University, in July, 19514-, and presented, in part, before the Ohio Academy of Sciences in April, 1955* Subsequently, June and July, 1955, infested mosquitoes were collected in Wayne Co., and these results are included here. In the course of the Gibraltar Island survey 1,781 adult Insects were examined (Table I). These include 11 families of insects representing six different orders. Five of these 11 families, representing three orders, have been found with water mite larvae attached. Of the 1,781 insects examined, 165 proved tq be infested with mites, an infestation rate of 9.3#- If only the infested families are considered the rate is 15.3$- Considerations of the individual groups follow:

EPHEMEROPTERA - Bone of the 225 mayflies examined In this study was infested. Similar results were found by the writer In examining mayflies of North Carolina. However, Lyman (personal communication) reported finding mites (not necessarily water mites) on imagoes and sub­ imagoes and Britt (personal communication) has described what was probably a water mite from a mayfly nymph. Bo nymphs were examined in the course of this study. ODONATA - Sixteen dragonflies from North Bass and 33

TABLE I

SUMMARY OF INFESTATION OF INSECTS WITH WATER MITES

(GIBRALTAR ISLAND AND VICINITY. JUNE - JULY, 19$k)

Number Number Per cent Insect Order Family Examined Infested Infested

Efcheraeroptera Ephemeridae 225 0 0 Odonata Aeshnldae 16 0 0

Agrionidae (?) 112 0 0

Plecoptera Perlldae (?) 7 0 0 Hemiptera Notonectidae 502 23 I*..6 Corixidae 90 1 1.1 Nepldae 3 2 66.6 Gerridae 31 0 0 Trichoptera Hydropsychidae 31k 0 0

Dlptera Tendipedidae 135 29.il- Culicidae 22 k 18.1 TOTAL 1781 165 9.3 3^ Middle Bass Islands and 112 damselflies from Gibraltar Island have been examined. None of these harbored water mites. However, Dr. E. E. Dickerman, Department of Biology, Bowling Green State University, has transmitted to the writer an infested dragonfly which was taken on North Bass Island during the summer of 1953* There are numerous reports in the literature of water mites para­ sitizing Odonata. PLECOPTERA - The insects of this group, because of their habits and habitat, might be expected to harbor water mites In abundance. Soar and Williamson (1925:23)j

Prison (1929) j and Imamura (1950) have recorded the stoneflies as hosts of water mites. The small sample examined in this survey is inconclusive regarding this group as hosts of mites in the Gibraltar Island region. None of the seven Individuals examined was infested. HEMIPTERA - For the hemipterans as a group, the infestation rate was there being 26 of 626 indivi­ duals infested. For the backswimmers (Notonecta undulata)

a sample of 502 individuals indicates an infestation rate

of i^.65 of these individuals were collected on 30 June, 195i| from two separate temporary ponds on South Bass Island, with notably different rates of Infestation. The infestation rates were three of 351 (0.3^) and 18 of 35

111+ (15.9#). (The discrepancy between 1+65 and 502 results from the fact that 37 notonectids collected at another time, two of which were infested, are included in the total.) One of 90 water boatmen (Arctocorixa sp. ) examined was found to be infested. The highest rate of infestation In the survey was found among a very small sample of water scorpions (Ranatra sp.). Two of the three individuals examined harbored water mites. One of these individuals collected on South Bass Island harbored 168 larval mites and nymphochrysalids. The mites on Notoneota undulata, Arctocorlxa sp., and Ranatra sp. are Hydrachna magniscutata Marshall. Details of their association with the host insects are considered In the systematic section of this report and in the discussion of life cycles. Thirty-one water striders examined yielded no mites. The gerrids are reported in the literature as hosts of larval and nymphal mites of the genus Limnochares (Soar and Williamson, 1925:17; Imamura, 1952a:231). TRICHOPTERA - Although the caddisflies are known to harbor larval water mites, none of 311+ Individuals ex­ amined In this survey was infested. This is a large enough sample to say that probably none of the water mites 36 of the region parasitizes adult trichopterans at this season. This, of course, does not preclude the possi­ bility that the larvae of these insects may act as hosts. Larval caddisflies were not examined for mites in this survey. DIPTERA - A large sample of tendipedid midges {i+^9

individuals) was examined and 135 or 29.1$ of these were Infested with water mites. Dr. Paul E. Arnaud, Jr., U. S. National Museum, has identified the midges as Tendlpes (Tendlpes) decorus (Johannsen). Midges collected at differ­ ent times and from different localities on Gibraltar and South Bass Islands showed rather consistent infestation. It is therefore thought that this is an especially sig­ nificant infestation rate. Reports in the literature in­ dicating midges as hosts of water mite larvae Include Imamura (1951) and Crowell (1950 and 1953). The mites recovered from midges In the present sur­ vey have been of two species. One nymph of v undulata was reared from a midge collected 6 July, 195k-, on Gibraltar Island. Larvae and nymphs of Piona reighardi have been collected and reared from midges taken on Gibraltar Island. Since mosquitoes are not abundant on Gibraltar Island, collections of these were made on South Bass Island. 37 While not many were collected (22), 18.1$ of those examined were infested. Unfortunately the vial contain­ ing this material was damaged and the material thus destroyed before determinations could be made. Subsequently three infested individuals of the genus Aedea were collected in Wayne Co., on 2J+ and 27 June, and 13 July, 1955* Two of these have been identi­ fied as A. vexans by Dr. C. E. Venard. Each of the three mosquitoes harbored larvae which appear to be identical with laboratory hatched larvae of Thyas stolli also collected in Wayne Co. The mosquitoes are frequently reported as hosts of undetermined water mites and in certain areas are known to be biological control agents. Uchida and Miyazaki (1935) have indicated that anopheline mosqui­ toes with five or more mite larvae attached cannot be induced to bite. This means, of course, that in the absence of a blood meal viable eggs will not be produced and the life cycle of the mosquito is thus interrupted. In his studies of mosquito biology Abdel-Malek (19^8:95*4-) records the occurrence of water mite larvae on Aedea trlvlttatus. During July, 19i|-7, he found that up to 20$ of his daily catches in Franklin Co., Ohio, 38 were Infested with mites which were identified as larval Hydracarina. As many as 15 mites were found on one mosquito* He observed that infested adults produced no eggs or gave fewer eggs than uninfested individuals.

t CHAPTER V

COLLECTION AND PREPARATION OP MATERIALS

In the course of the present study an attempt has been made to make collections In localities and ecologi­ cal situations typical of the central and north-central Ohio area. Eighteen counties have been visted with mites being taken in twelve counties as indicated on the accompanying map (Pig. 18). Mites have been collected from such varied habitats as temporary vernal ponds* artificial farm ponds* woodland pools* swamps and marshes* permanent ponds, and a variety of ecological niches in Lake Erie and Buckeye Lake. A single specimen in the collection was collected from one of a series of ponds In Sandusky and Erie Counties* which are locally known as Blue Holes. These are a limnologioal phenomenon unique in Ohio in the fact that they are fed by under­ ground streams which course through the underlying dolo­ mite. Mites have also been collected from a flood con­ trol impoundment in Tuscarawas County. Rivers and streams in several counties have been notably unproductive. In the localities visited, random sampling has not been attempted. The object of the present study has been i|0 to collect mites rather than to compare populations of selected environments, and such comparisons have been only incidental to the primary aim. Several collecting techniques have been utilized, these being adapted to the particular environment being worked. Most of these represent standard techniques or slight modifications thereof. The most generally useful apparatus has been a Birge net cone (Figs. 19 and 20). Cook and Mitchell (19^2) have expressed definite objections to its use for collecting water mites on the grounds that bottom dwelling species are missed. This has not been the case in collecting activities in connection with my study. Certain bottom dwelling forms in the writer1s collection have been taken only with the Birge net, although the same area has been carefully worked by other techniques. The cone is of l/ij.-inch hardware cloth % 1/2 inches in diameter at its base and 6 inches high. To the open end is attached a net of 60 mesh per inch silk grit gauze. The trailing end of the net is gathered around a flange of 7/8-inch copper tubing and fastened with a rubber band. To the other end of the tubing is attached a 1 1/2 x 3 inch silk bag, held over a flange by a rubber band. These bags, filled in tow­ ing, are removed and an identification number dropped in. kl The bag is then closed with the rubber band and trans­ ported to the laboratory in a container of water from the environment. Collection data are recorded in the field in a notebook along with the identification number.

In addition to date, time of day, and precise location, climatologlcal and ecological data may be recorded. In the laboratory the contents are removed and examined un­ der the dissecting microscope. This method reveals mites of a size that would certainly be missed in field sorting.

For large areas of open water, such as permanent ponds and lakes, the Birge net Is the only device that I have found satisfactory. It is especially convenient for collecting In water too deep for wading. It may also be towed from a rowboat or launch. In all situations it has been desirable to equip the net with an outer canvas sleeve to protect the net from snagging on underwater debris.

Temporary vernal ponds and woodland pools are most conveniently worked with a long-handled, white enameled dipper such as is often used in mosquito survey work.

Wading in the pool and dipping among the floating and emergent vegetation will frequently yield numerous mites, at the same time avoiding much debris which would be accumulated in a Birge net sample. Hites thus taken in 42 the dipper are transferred to numbered vials by means of a dropping pipette. The dropping pipette used In this procedure Is made of a standard medicine dropper tube and an ear syringe bulb. This apparatus has the dual advan­ tage of being easier to manipulate by cold hands in Icy water and of floating at the surface if inadvertently dropped. For collecting In woodland pools, spring ponds, and other environments where surface swimming mites may be present in relative abundance the writer has developed an original device called a dipping-horn (Crowell, 1954)• The dipping-horn Is constructed of standard plumb­ ing fittings (Fig. 21). Part A is a brass fitting called a flush L, with the short leg cut off. Part B is a brass escutcheon plate with a large diameter equal to that of the flush L (2 inches) and tapering to a diameter of 7/8 inch. This receives part C, a piece of 7/8-inch copper tubing. The free end of the copper tubing Is flanged to facilitate attachment of a 1 l/2 x 3 Inch silk bag. The bag Is held in place by a rubber band. The handle Is a piece of 1/2-inch copper tubing. All parts are soldered together. The dipping-horn Is 10 l/4 inches long overall. The device is used by dipping under mites which can be seen swiaaalng at the surface and scooping them Into the *4-3 horn. The horn is then tipped up in order to accumulate them in the bag. After an area has been worked the bag is removed, supplied with an identification number and closed with the rubber band. The collection can be subsequently sorted in the laboratory if necessary. In swampy and marshy environments with profuse submerged and emergent vegetation the writer has used a panning technique as a supplement to Birge net collecting which consists of removing debris and vegetation to a white enameled pan, and subsequent collecting of mites with a dropping pipette. This method has an advantage over the Birge net technique in that the collector is immediately aware of the progress of the collecting but the disadvantage of consuming much of the time spent in the field. For any particular situation one must weigh these factors and reach an appropriate decision. Wave-swept rubble beaches and shelving rock at var­ ious localities on Lake Erie have been successfully worked by a modification of the panning technique (Fig. 22). In this procedure rocks are taken from the water, a few at a time, and placed in a white enameled pan containing a little water. The rocks are then brushed with an ordinary stiff scrub brush. Attached mites and other organisms are thus dislodged from the rocks Into the pan. The mites are ijij- then collected with a dropping pipette. Frequently numer­ ous mites may be thus collected in a short time, and this technique has been especially productive of the heavily- plated, clinging lebertiids. Other methods of collecting water mites have been reported from time to time, Marshall has reported on mites

collected from the stomachs of fishes (1929c and 1933 ) and stomachs of turtles (19l(.0a). Certain water mites are attracted to the vicinity of an electric light or a flash­ light suspended close to the surface of the water. Cook and Mitchell (19E>2) have described a seining technique for collecting water mites inhabiting streams. I have used this technique for collecting host species and its opera­ tion will be considered in that connection. For mites I see in it the objection that many small forms would probably be lost. In addition to the collection of free living stages of water mites, some attention has been given to the collection of host . The information gleaned from these collections Is indicated elsewhere In this report (Chap. IV) and only the techniques involved will be considered here.

The unionicolids, which are regularly associated with mollusks at all stages of their development, can be kS collected by dissecting parasitized hosts. The mites may also be collected from aquaria or dishes of water in which host mollusks have been kept for several hours. These mites are most frequently found in clams, but have also been reported in snails (Chandler, 193U)• Insect hosts have been more extensively collected and examined in this study than have molluscan hosts. Aquatic insects have been taken by means of dip nets and bottom scoops. These techniques have yielded numerous parasitized Hemiptera. The scrubbing technique described above yields nnt only mites but also many Insect larvae. These have been examined but have not yielded parasitic mites. The seining technique referred to previously re­ quires a two man team for its most efficient use and it has been of greatest value in stream habitats. A square of bronze or plastic screening material is attached to wooden handles. The screen is held by one operator in a down-stream location among stream riffles. The other operator walks upstream a short distance dislodging stones, sticks, and other debris. Insects clinging to these are accumulated on the screen by the stream currents. In the present study no parasitized insects have been recovered by this technique, though in other geographic areas the writer has employed this technique with success. *4-6 Adult stages of the Odonata examined in this study have been collected principally by aerial net. The night-flying Diptera have been collected by taking advantage of their positive phototactic responses. Automobile headlights have been employed as a light-trap, with a pan of liquid propped just below the light. Ethyl alcohol of approximately 70% concentration may be employed if the collections are to be preserved immediately. In most cases, however, it has beendesirable to keep any mites collected alive for subsequent observation. For this reason water with detergent added has been 'used in­ stead of alcohol. Several of the commercial household detergents have been used successfully. Convenient as this technique is, it has not been extensively used in this study. More efficient has been the attraction of insects to a spot of light from a flashlight beam directed on a sheet of white fabric. Insects so attracted have been collected in an aspirator and subsequently etherized for examination under a binoeular dissecting microscope. At the Stone Laboratory on Gibraltar Island In Lake Erie, where a portion of this work was carried on, the writer was frequently able to collect 250 to 300 midges In 15 to 20 minutes from the screens of lighted k7 laboratory windows. These were collected by aspiration and anesthetized for examination. In all cases infested insects were sorted out and kept in or over water in screened containers, awaiting detachment of mites following feeding. In instances where several mites were present on an individual insect, repre­ sentative forms were mechanically detached and mounted for subsequent study. In all collections representative individuals have been kept In rearing chambers for laboratory observation. Though several types of dishes have been used, small (1- Ineh diameter) stender dishes with ground, fitted covers have proven most convenient. The ground covers retard water loss from evaporation, and their small size makes the whole dish observable in the field of an ordinary- dissecting microscope. These rearing chambers are given serial numbers, and periodic observations are recorded on note pads kept with the cultures. Such cultures have routinely been examined at intervals of a few minutes to several days, depending upon the information being sought. Several unsuccessful attempts have been made to infest Insects with water mite larvae. In these attempts Insects (reared or collected) have been exposed to mite larvae hatched from eggs laid in rearing chambers. Species 14-8 to be exposed have been chosen primarily on the basis of availability, therefore the trials have been empirical. Such a trial and error approach Is justified since there is very little Information available on specifity of host-parasite relationships in this group. Though various killing and preserving agents have been used from time to time in the course of this study, best results have been obtained by using an acetic acid- glycerin-water mixture known to hydrachnologists as Koenikefs fluid. Numerous modifications of the preserva­ tive have been tried since Koenike*s original designation of the proportions. The mixture used by the writer con­ sists of 10 parts glacial acetic acid, £0 parts glycerin, and lj.0 parts distilled water. Mites to be stored have been placed In rubber-stoppered tubes of the sort In which procaine is supplied to the dental profession. These measure approximately 10 x. 75 ram. * thus being small enough for efficient storage and yet large enough for a convenient size data label. Evaporation from a well-stoppered vial is very slight, therefore specimens are almost never lost by dessication in this procedure. Though most mites can be mounted for study directly from Koenike's fluid, it is sometimes necessary to clear specimens. The most generally satisfactory material has 1*9 been a lacto-phenol mixture consisting of equal parts of lactic acid and liquefied phenol. Clearing is facili­ tated by puncturing the integument, thus making for more rapid penetration. After a short time, usually a few hours, the body contents can be forced out by pressure. Newell

(I9I4-?) has outlined a technique employing enzymatic diges­ tion for clearing but I prefer the simpler lactophenol technique. Water mites have been routinely mounted in a modi­ fied Berlese medium known as Hoyer*s solution. This medium has a clearing effect sufficient for most mites encountered in this study. Mites can be mounted directly Koenike's fluid, from water, or from other aqueous media. The writer* s experience has been that mites kept in Koenike*s fluid even a few days will make more satisfac­ tory permanent mounts than those mounted from water. Thick mounts, especially those made directly from water, may show shrinkage of the media and resultant distortion of the specimen. If this happens the cover slip can be soaked off in water and the specimen remounted. The following formula and directions for making Hoyer*s mounting medium are taken from Baker and Wharton (19£2): 5o

5>0 grama distilled water 30 grams gum arable (clear crystals) 200 grams chloral hydrate 20 grams glycerin The ingredients should be mixed at room tempera­ ture in the above sequence.

While specific treatment and orientation may vary with the forms under preparation, it has been general procedure to mount specimens ventral surface uppermost. It is essential that mouth parts be dissected off repre­ sentative individuals, though all in a series need not be dissected. It may also be desirable to remove legs from the mite. Dissection is done in the drop of mounting medium, and a No. 1 cover slip is lowered carefully Into place. In some cases it has been desirable to separate venter and dorsum of the mite by dissection. Dissection is performed under a dissecting micro­ scope. Needles have been fabricated, modified slightly from a design described by Butler and Grundman(1953)♦ The needles are made of No. 0 or No. 00 stainless steel insect pins, slipped through the opening of a No. 21 B-D hypodermic needle. A wooden handle of appropriate diameter and taper is cemented into the socket of the hypodermic needle. The shaft of the hypodermic needle thus supports the insect pin to a distance within 5 inm. of the tip. Needles prepared in this fashion have proven to be much more efficient and of more permanent construe- £1 tlon than the usual mlnuten pins glued or bound to applicator sticks. Slides must be labeled immediately upon prepara­ tion. It has become customary to reserve the left hand label for identification data, placing locality arid col­ lection data on the right hand label. Newell (19ii.7) describes a technique of making per­ manent mounts In glycerin jelly. This method has been In use for many years by European workers and has met with some favor in this country in recent years (Mitchell and Cook, 1952). In this technique dissected mites are mounted between a small and a large cover slip, and the whole preparation then mounted in balsam, with the large slip uppermost. With practice very fine preparations can be made In this manner. The technique has been used by the writer, but It Is felt that the difference In end result is not great enough to compensate for the excessive increase of time required. The desirability of good optical equipment for the examination of specimens cannot be overemphasized. Care­ ful microscopic examination is essential to the deter­ mination of setal patterns and Integumentary structure necessary in the identification and description of mites.

Elias (195>0) has pointed out the desirability of making precise graphic records in the study of scientific material. In this study drawings have been used as a means of recording details observed in microscopic examina­ tion. These drawings have been prepared on cross-section paper with a standard ocular grid as a drawing guide. Subsequent comparisons are made on the basis of these drawings as well as with actual materials. CHAPTER VI

SYSTEMATIC RECORD OP OHIO WATER MITES

Tha collections which are here reported began in the spring of 1952 and continued through the summer of

195 6 , with additional material transmitted to the writer in the spring of 1957* The material reported includes 11 families encompassing 12 genera. In all 19 species are recorded, four of which are new* The order of presentation follows that of VIets (1956). It had been the writer*s intent to prepare keys for the identification of the species reported. However, since most of the families are represented by a single genus, and most of the genera by a single species, it seems inadvisable to present keys. Inasmuch as there are certainly many species still to be collected in Ohio, keys to the currently known species would probably be mislead­ ing and of doubtful value. Useful keys to the genera are already available in Pennak (1953).

I. FAMILY HYDRACHNIDAE

The family Hydrachnidae includes two genera of mites. Only one of these, the genus Hydrachna Mflller, has been 53 5k recorded from the United States. The genus is represent­

ed in the present study by three species. H. (Hydrachna) magnlscutata Marshall, 1927 is here reported from South

Bass Island (Ottawa Go.) and from Buckeye Lake in Licking

and Fairfield Counties. A male specimen and a nymph of

H. (Scutohydrachna) rotunda Marshall, 1930 have been

collected in Franklin County. A new species in the sub- genus Rhabdohydrachna has been collected in Wayne and

Licking Counties.

Hydrachna magniscutata Marshall, 1927 Adults of this species are characterized by the presence of a single large dorsal shield projecting slightly between the eyes. The anterior margin of this projection is irregular In outline, generally slightly concave. Females In the Licking Co. collection possess the plate as well developed as males from both locali­ ties. Marshall (1927:271) records three nymphs, collect­ ed with a series of H. magniscutata, in which a dorsal shield was wanting or varying In outline from the adults collected. She concluded these were of nspecies as yet undescribed.11

There is considerable variation in color among

Individuals. Marshall (1927:271; 19^6:352) has reported the collection of blue specimens. The writer*s notes re­ cord both red and green specimens from the same pond on 55 South Bass Island. Specimens from the Buckeye Lake col­ lections were checked against Munsell (1929) color stan­ dards and the following variations have been noted:

Bluish Blue-Green, 7.5 BG 7A and 7-5 BG 5A; yellowish

Red, 7*5 R 6/8. Still another individual is noted "dark red in color."

Marshall (19)4-6 :3 5 2 ) indicates that this species "has been found in over twenty bodies of water in Wiscon­ sin and across the United States from New England to Wash­ ington as well as in Ontario and Alberta." Hoff ( 1 9 A 1 I(.9) records its occurrence in Reelfoot Lake In Tennessee. A large series of specimens of H. magnet scut ata was collected In June, from temporary ponds (Burggraf»s Ponds) on South Bass Island. While many mites were taken free In these collections, more were collected attached to host Insects. Of £02 backswlmmers (Notonecta undulata) 23» or were infested. Only one of 90 water boatmen (Arctocorixa sp.) harbored mites. Two of three water scorpions (Ranatra sp.) were Infested, one of these with 168 Individual mites (Pig. 23). A smaller series of 29 specimens was collected on 2)4. August, 1956,from Buckeye Lake. The series includes nymphs and adults, and was collected in mats of Cladophora and Myrlophyllum. 56 Female. Females in the present collection average 1.82 mm. in length. As previously pointed out, those of Ottawa Co. collections lack the dorsal shield typical of the species. The shield of a female in the Buckeye Lake collections is represented in Figure 2ij.. The ventral epi- raera of the female vary slightly from descriptions given by Marshall {19I4.6 ) and Lundblad (193k-) • indicated in Figure 25» the postero-medial angle of epimeron IV is slightly attenuated. These angles partially enclose the external genitalia. The setal pattern of the epimera is indicated in Figure 25. The external genitalia presents an omega-shaped outline. When not everted as in Figure 25 the posterior margin shows an inverted V-shaped notch in which the ori­ fice is situated. The chelicerae are, as in other species of the genus, saberlike (Fig, 7). The palpal genu (P-3) is much elongated, being about 5 times as long as it is wide. P-l and P-2 are somewhat more truncate. The distribution of setae is constant (Fig. 26).

Male. The males of H. magnlscutata are in general smaller than the females, averaging 1.3 mm. in length. The sexes appear to occur in about equal numbers. All males in the writer's collection bear the dorsal shield 57 (Pig. 27). There is slight variation in shape of the shield among individuals. As in the females, the epimera are arranged in four groups of two each (Pig. 28). Postero-medial angles of the fourth epimera are more rounded than those of the fe­ male. The setal pattern of the epimera is constant and differs from that of the female in that a pair of setae on the posterior margin of the fourth epimera of males lies free in the post-epimeral integument of the females. The external genitalia present a more squarish appearance than that of females. The pedipalp (Pig. 29) differs from that of the fe­ male in proportions, especially proportions of P-l and P-3.

Nymph. Nymphs of this species present characteris­ tics permitting separation of specimens into two morpho­ logical types. The writer has interpreted this variation as provisional sexual dimorphism. On the basis of charac­ teristics of the ventral epimera it has been possible to correlate nymphs and adults, and thus to separate provir „■ - sional females (Pigs. 30, 31» 32) from provisional males (Figs. 33* 3k> 35). There appears to be no record in the literature of this situation occurring in other species of the genus. Most readily apparent differences are in the dorsal 58 shields. The shield of provisional females occurs in the form of two pairs of separate plates (Pig. 30); that of provisional males consists of only one pair of plates (Pig. 33). The plates of provisional females lie close to and curve around the eye capsules, while those of provisional males are farther removed. Correlation of nymphs and adults has been based on the characteristics of the postero-medial angle of the fourth epimera. This angle is attenuated in provisional females (Pig. 31) as in adult females, rounded in provi­ sional males (Pig. 3^) as In adult males. Setal patterns of the nymphs differ in that setae on epimera I of females have not been seen on epimera I of males. The palpi of the nymphs show differences in propor­ tions similar to those of the adults, those of provisional females (Pig. 32) being more elongate than those of provi­ sional males (Pig. 35).

Larva. A large series of laboratory hatched larvae of E. magniscutata averages 0.37 mm. in length. More than a third of this body length (0.15 mm.) is represented by the gnathosoma. The venter of this region is armored with paired gnathosomal plates (Pig. 36). The venter of the podosoma bears three pairs of epimera which occupy another 0.15 mm. of the body length. 59 The first and third epimera each bear a single prominent seta. The posterior margin of the body has four pairs of setae arising from the ventral surface and three pairs from the dorsal surface. A nymphochrysalid of H. magniscutata (Fig. 37) is drawn to the same scale as the unfed larva in Figure 3 6 . Comparison indicates an increase of 300% in linear dimen­ sions. Accompanying this increase there is separation of epimeral sclerites, presumably due to stretching of the soft Integument between them, and some distortion of scler- ites. The nymphochrysalld figured was mechanioally de­ tached from the host Insect. The developing nymph is clearly apparent within this and other similar specimens.

Bggs. Four females of this species kept in a rear­ ing dish of pond water deposited eggs within two days after their collection on 30 June, 195^- Within six days from collection over 100 eggs had been deposited singly on the bottom of the dish. These eggs, Illustrated in Figure 3 8 * were slightly ovoid In shape and measured 0.2 ram. in their longest dimension. They were pale orange in color. Mar­ shall (19i4-6 s352) reports that laboratory reared specimens were observed to deposit eggs In galleries formed in Potamogeton richardsonii. 60 In the present study, developing larvae could be seen within the egg capsule seven days after deposition. Larvae were well developed within lij. days, and within 17 days all were hatched.

Developmental observations. In the present study there has been an opportunity to make observations on the habits and life history of H. magnlacutata. in addition to adult mites, backswimraers (Notonecta undulata), a water boatmen (Arctoeorlxa sp.), and two water scorpions (Rana- tra sp.) Infested with larvae and nymphochrysalids of this mite have been collected. Laboratory observations

of a water scorpion naturally infested with 168 larvae and nyaaphochrysalids indicate that after feeding the larval mite remains attached to its host while undergoing trans­ formation to the nymphal stage. Once the transformation is completed the newly formed nymph emerges through a

transverse slit in the larval skin about 2/3 of the body length from the anterior end. The empty larval skin re­ mains attached to the host. Nymphs of the mite have been observed inserting their chelicerae in the soft Integument of the insect be­ tween leg segments, presumably feeding. This indicates that the nymphal stage of this species Is also parasitic. 61

Hydrachna rotunda Marshall, 1930 S* rotunda is represented in the present collection by one male specimen and one nymph. The original descrip­ tion (Marshall, 1930:21^6) was based on a single male taken in Adams Co., Wisconsin. The species has subse­ quently been reported from several lakes in Wisconsin and from Illinois (Marshall, 1914.6:353) and from Reelfoot Lake, Tennessee (Hoff, s I4.9 ) - The specimens here re­ ported were collected on 7 August, 1956, from a farm pond on the Ohio State University campus In Clinton Twnp., Franklin Co., Ohio.

Adult. The male specimen in this collection measures 1.15 mm. long by 1.10 mm. wide (Fig. 39). In life the dorsum was highly arched, giving a globose appear­ ance to the body. The color of the living mite was bright red, 5*0 H I4./II4. of Munsell (1929). The dorsum Is covered by an extensive, finely sculp­ tured plate which reaches down the sides and onto the ven­ tral surface. The eyes project prominently through two non-sclerotized areas at the antero-dorsal margin. A pair of indistinct, Irregular sclerites is situated on the dor­ sum, posterior to the eyes. The epimera are situated within a diamond-shaped 62 area formed by the boundaries of the dorsal plate. Pos- tero-medial angles of epimera IV are extended into a rounded and curved process, partially surrounding the external genitalia. The genital plate is broadly obovate in shape, with the aperture toward the posterior end.

Nymph. The nymph of H. rotunda appears not to have been previously recorded. The extensive integumentary shield of the adult is wanting in the nymph. The provi­

sional genitalia (Pig. I4.0 ) consist of two widely separated, nearly oval plates. Laterally the plates are situated in close proximity to epimera III and IV. Antero-laterally a slight angle on the margin of the genital plate rests, in a similar angle formed by the medial margins of epimera III and IV. The nymphal palp (Pig. ij.1) shows the elonga­ tion of P-3 characteristic of the species. The two specimens were observed In the laboratory to feed upon a third mite in the same rearing chamber. The specimen thus fed upon was mutilated beyond determina­ tion. It had been sorted out with these two on the basis of similar appearance, and presumably was the same kind. Cannibalism has been observed among the water mites on other occasions. 63

Hydrachna baculoscutata, n. sp. Diagnosis. Hydrachnids with characteristics of the genus Hydrachna, the dorsal armor of adults consist­ ing of two rodlike and two rounded sclerites. Rodlike shields bearing knoblike protuberances. Nymphs with rodlike sclerites on dorsum. Frontal organ prominent.

Sixteen specimens in the writer*s collection repre­ sent a new species of the subgenus Hydrachna (Rhabdohy- drachna.) The species is characterized by the presence of a pair of rodlike anterior dorsal shields, each of which bears in adults six knoblike protuberances near its posterior end. For this species the name Hydrachna baculoscutata is proposed, in reference to the rod-shaped plates making up the dorsal armor.

Males and females are dark red in color, 5*0 R 3/8 of Munsell <1929). Nymphs are slightly brighter red. Hydrachna baculoscutata was first brought to me by Mr. Joseph Beatty, who collected three specimens in Brown*s

Lake, Wayne Co. (Rllj.WTl8NS21) on 1 April, 1952. Subse­ quently I collected additional specimens on 12 and 27 April, 1956, in a woodland pool on the Edge-rly farm in

Licking Co. {RII4.WTI3NS7 ). In the latter collections all 6lj. specimens were taken as nymphs attached to Myrlophyllum. Most of these subsequently transformed and molted, emerg­ ing as adults.

Female. A single adult female taken In Licking Co. measures 2.88 ram. in length. In addition to the club- shaped antero-dorsal plates there Is a pair of dorso­ lateral plates, each of which bears a prominent seta (Fig. kZ). The external genital apparatus lies well within an open bay formed by epimera III and IV (Fig. 14-3). The genital apparatus appears to be anchored to underlying projections from the third epimera. The genital plate is cordate in outline, with a deep incision in the posterior margin marking the position of the genital orifice (Fig. i+JLf-). Palpal proportions and setal patterns are shown in Figure

Male. The average length of four males in the col­ lection Is 2.71 mm. The anterior dorsal shields of males (Fig. i|.6 ) are smaller than those of females and differ slightly in outline. Dorso-lateral sclerites present in the female have not been observed in males. The external genital apparatus Is only partially enclosed in the bay formed by epimera III and IV (Fig. Ii7). As in the female the genital apparatus appears to 65 be anchored to processes from epimera III. The genital apparatus Is broadly cuneate in form with wide anterior and posterior indentations. The genital aperture lies in the posterior indentation. Characteristics of the palp are shown in Figure I4.8 .

Nymph. As In the case of Hydrachna magnlscutata mentioned above, the nymphs of H. baculoscutata are separable into two morphological types. As in the pre­ vious species I have interpreted this as provisional sexual dimorphism. Figure ij.9 represents the dorsum of a nymphal skin from which the male individual in Figures

Ij.7 and i|_8 emerged. This must therefore be recognized as the provisional male. Figure 50 shows this individual, prior to molting, with mouth parts deeply embedded in the tissues of a Myriophy 1 lum stem. Note that in Figure 50 legs 1 and 2 have been omitted for clarity. The venter of this individual is shown in Figure 51- Epimera III show well-developed medial processes which are also prominent In the adult male. The genital plates are oval In outline, their long axis tilted about 30 degrees from the midline of the body. Characteristics of the palp of this individual are shown in Figure 52. The dorsum of a provisional female is shown in Figure 53* The anterior dorsal plates present constant 66 differences from those of the provisional male. The plate is twice as long and the knoblike protuberances occur at the middle of the plate in provisional females rather than at the posterior end of the plate as in provisional males. Setae flanking the plates of the provisional female have not been seen in provisional males. Figure 5k shows the epimera and genital plates of the provisional female. Epimera III lack the anchoral processes seen in provisional males and In adults of both sexes. Genital plates of provisional females are more rounded In outline than those of provisional males. The palpus of the provisional female is shown in Figure 55. The palpus Is similar to that of provisional males In general proportions but bears fewer setae. De­ tails of the attachment of the nymph to Myriophyllum are shown In Figure 56. Note that the rostrum of the gnatho- soma, together with the chelicerae, are inserted to a depth of two to three cells into the plant tissue.

Developmental observations. The attachment de­ scribed above has been noted only in the period just prior to emergence of the adult. It is apparently not a feed­ ing reaction. Since all specimens collected by the writer were already attached to the plant, it has not been possi­ ble to determine the length of this inactive imagoehry- 67 salid stage. However, all that emerged have done so in not less than three nor more than four days after col­ lection.

Comparisons. Hydrachna baculoscutata can be differentiated from all other species of the genus in the shape of its anterior dorsal plates. It bears greater re­ semblance to H.comosa Koenike, IQ96 and to crassipalpis Piersig, 1897 than to other species of the genus. The dorsal plates of H. baculoscutata are shorter and straight­ en than in these two forms. Both H. comosa and H. crasai- palpls are palearctlc forms not recorded from this coun­ try up to the present time.

Type material. Holotype and paratypes of Hydrachna baculoscutata will be deposited in the Chicago Natural History Museum. Other paratypes will be retained In the writer*s collection.

II. FAMILY EYLA3DAE

The family Eylaidae Is represented In this study by specimens collected In Ashland (Rll|.WT20NS22/23), Licking (Rli|.WT3NS7 and R15WT2N), Ottawa (North Bass Is­ land), and Wayne Counties (R12WT17NS11, R13WT15NS32, R13W T16NS31, Rli|.WT20NS25> and Brown* s Lake). 68

Eylals extendens Milller, 1776 Mitchell (195M3^-35) has included in this species mites reported under nine other specific and varietal names. Each of the individuals in the present collection appears to be identical with one or another of these variants. Viets (1956:62-65) does not indicate this species from North America, apparently not accepting Mitchell* s treatment of the group. The limited material presently available does not permit a clarification of this problem though the writer is inclined to include all but E. lnfundibulifera as synonyms. Viets (19^9), in an

extensive paper on the species, figures 91 variations of the ocular plate, which is considered a significant species characteristic. All of my Ohio material falls within the range of variation figured. Comparisons have been made with specimens of Eylais extendens loaned by the Chicago Natural History Museum, with which the Ohio material appears to be identical. These are relatively large mites. Ten of the speci­ mens in the Ashland County collection averaged 1+.$ mm. in length; those taken in other collections have been some­ what smaller. Living specimens have a brick-red color: yellowish Red, 7*5 R 3/10 of Munsell (1929). 69 The species of this genus are separated princi­ pally upon characteristics of the ocular plate which is borne on the anterior dorsal surface of the body. The double, laterally situated eyes are enclosed in sclero- tized capsules joined by an interocular bridge. In E. extendens the length of the interocular bridge (,!.£. the distance between eye capsules) is less than the antero­ posterior dimension of the eye capsule. Several of the variations encountered In the present collections are shown in Figures 57-66, Figure 66 representing the bridge of a nymphal specimen. In Figures 57 to 61}. It will be noted that the anterior margin of the bridge shows either one or two marked Indentations. In none of these does the bridge extend anterior to the capsules. A single specimen from North Bass Island has a prominent anterior projection extending well beyond the eye capsules (Fig. 65). This plate agrees with a figure of E. infundibuli- fera bakeri described by Marshall (I9I4.6 ), which Mitchell (195!}-) has included among the synonyms of E. extendens. Figure 67 shows the ocular plate of a specimen borrowed from the Chicago Natural History Museum which was collect­ ed at MOrand Rapids, Mich., summer, 1895*” As indicated previously, under the name E. extendens this species has not been previously recorded from North 70 America. Under the several synonym!zed names it has been recorded from Tennessee (Hoff, 19i+U:i+8) and from North Carolina, Michigan, and Wisconsin, as well as several localities in Canada (Marshall, 19i|.6:356-358) * All of the writer’s material has been taken from standing water environments, generally of a temporary nature, and high in organic debris. This species is most readily collected in the springtime. The single Ottawa County specimen was collected on 15 July, 195^- Pour Licking County specimens were collected on 30 July, 1956. The Ashland County specimens were collected on 20 May, 1956. The remaining 51 specimens from Licking and Wayne Counties were collected between 2 April and 27 April in 1952, 195il, 1955, and 1956.

Adult. The following description of the adult is based primarily on the female, there being only minor differences in the sexes in characteristics other than the genitalia. Females and males are present in the writer’s collection, in approximately equal numbers. Females are generally larger than males; twelve females average 3.37 nan. in length and ten males average 1.79 ram. in length.

The venter (Fig.6 8 ) shows the epimera arranged in four groups of two each. Epimera III and IV are, however, 71 almost completely separated by a pronounced cleft begin­ ning laterally. Setae, varying in number, are arranged in an irregular single row on each epimeron. Setae near the lateral end of the row are somewhat shorter and stouter than the more medial setae. The external genital apparatus is situated well forward in the Inter-epimeral space, between the medial ends of epimera I and II. The genital plates of males (Pig. 71) are notably more setaceous than those of females (Pig. 6 8 ). A prominent excretory plate and pore, flanked by several stout setae, are situated in the mid-line, a varying distance posterior to the genitalia. The integument, in non-sclerotized areas, beans numerous papilliform glands many of which are double (Pig. 72). No definite pattern of their arrangement has been discernible. The mouth parts are shown In Figures 69 and 70. The gnathosomal plate presents a trefoil appearance, with the stomatal aperture occupying an antero-medial position (Pig. 69). The palpus (Pig. 70) is slender and elongate, exhibiting a non-sclerotized area on P-2. There are numerous simple setae and a few plumose setae, the number being somewhat variable. A prominent plumose seta on the medial surface of P-ij. appears to be constant among indivi­ dual 8 . 72

Nymph. A nymph of this species, one of several collected in Licking County, is represented in Figures 73 and 71}-. The ventral epimera show an arrangement simi­ lar to that of the adult (Fig. 73)* Epimeral setae, especially of epimera I and II, are more numerous and less regularly arranged than those of the adult. Provisional genitalia are wanting. A small excretory pore is located medially at the level of epimera IV. Characteristics of the nymphal palp are shown in Figure 7^1-•

Larva. The average length of 11 laboratory hatched larvae is 0.187 mm. Figure 75 shows the venter of one of these individuals with leg bases inoluded. The setal pat­ tern shown appears to be constant among individuals. The gnathosoma of this larva is relatively smaller than that of certain other species (e.g. Hydrachna magniscutata).

Eggs. Eggs laid in a rearing chamber by a gravid female collected In Ashland County are shown In Figure 76. This shows a portion of a large clutch of eggs laid on 22 May, 1956, On that date the egg a were checked against Munsell (1929) color standards. They are recorded as yellowish-Red, 7-5 R $/l0. Note that several of the eggs are arranged In clusters of four eggs with a separate gel­ atinous capsule. Fine particles of debris are present In 73 the surface of the entire mass. Thirty-three clutches of

eggs laid by mites of this species vary in number from 15 eggs to an estimated If00 eggs.

Developmental observations. On 25 May, 1956, a female from the Ashland County collections was observed ovipositing. This was accomplished with the female laying on her back, with eggs accumulating on the venter at the level of the genitalia. Legs I, II, and III flexed in receiving the egg mass. At Intervals of several seconds the whole mass was moved forward as new eggs were added. Three days later this female was dead. Five clutches of eggs on which dally observations were made showed minimum hatching time from 12 to 19 days after deposition, with an average of lif.lf days. On several occasions recently hatched larvae were observed skimming the surface of the water, though most remained In the water swimming actively about. On 12 April, 1956, several nyraphal specimens of Eylais extendens were collected in Licking County, Inac­ tive and attached to leaves and stems of Myriophy1lum. This attachment was by wrapping the legs around the stem; mouthparts were not Involved as they are in Hydrachna bacu- loscutata. Four days later, on 16 April, 1956, these Individuals had molted, leaving the nymphal skins attached 7k to the plants. The length of the imagochrysalid stage has not been determined since It had already begun when the specimens were collected. Eight days later (2k May, 1956) these individuals were dead. This series of observations suggests that the over­ wintering stage of E. extendens Is the nymph. In early spring the nymph enters a brief imagochrysalid stage. Following this, molting occurs and the adult emerges. A brief period of adulthood (during which we must speculate that mating occurs) Is culminated in the production of many eggs. Shortly after oviposition the adult dies. Larvae hatch In approximately two weeks after oviposition. Again we must speculate that larvae undergo a subsequent attachment to a h o s t as yet unknown. Viets (1936:

Ij.95) says of Eylais larvae: Sie befallen die verschiedevartigen Wassertiere, z. B. Odonaten?, TIpula, vor allem aber Wasser kafer und - wanzen, Cymatla, Dytisciden und Gyrinlden, Hydrophilinen — auch an Kiemenblattchen von Fischen warden sie gefunden.

III. FAMILY THYASIDAE

This, and the subsequent family Hydryphantidae, are Included in the single family Hydryphantidae In Mitchell’s checklist (Mitchell, 1954)* Such a scheme follows that of Lundblad (19l|l) wherein he says: "Der 75 einzige Unterschied besteht im Fehlen order Vorhandsensein von Schwlmmenhaaren. Ich find© eine solche Augteilung ganz unberechtigt.M However, there are notable differences in sclerotization of the dor stun in these two groups, and this writer feels the separation is warranted, following Viets (1936 and 1956).

Thyas atolli Koenike, 1895 The family Thyasidae is represented in my collec­ tions by numerous specimens of Thyas stolli, which is the only species of the genus thus far recorded from North America. This species was described by Koenike (1895) from specimens collected In a marsh in the Canadian

Rocky Mountains, on 10 August, 1883* McClure (I9J4.3 ) reported T.stolli from Manitoba and Habeeb (195il} has re­ ported it from New Brunswick. The writer* a determination has been based on com­ parison with specimens loaned by the Chicago Natural History Museum, which were collected 29 June, 1936, Churchill, Manitoba, by ¥. Erm. In the present survey it has been collected from four Ohio counties: Ashland (R16WT23NS11), Fairfield

(R18WT17NS32), Licking (R11j.WT3NS7) , and nine locations in Wayne (R11WT17N, R12MT17MS12 and S31, R13WT15NS31, 76

RI3WTI6NSI4. and S31, R13WT17NS33, Rli*.WT19NS32 and Rllj.WT20N- S25)• The earliest seasonal collection was 6 January, 1955 and the latest was 9 May, 195^* It has been collected from temporary woodland pools In the years 1953-56 by the writer, and numerous specimens collected in April, 1957, by Dr. C. E. Venard, have been transmitted to the writer.

Adults. The dorsum of adult mites of this genus is characterized by the presence of plates of three dis­ tinct types (Viets, 1936:101*.): 1, Irregular, rounded plates with neither setae nor gland-poresj 2. Plates with setae but lacking gland-poresj and 3* Plates with both setae and gland-pores. The distribution of these plates for T. stolli is shown In Figure 77. The specimen from which this figure was made is a male collected In Lick­ ing Co. on 27 April, 1956. An unpaired plate of the first type, the frontale, lies in the midline and bears the frontal organ. Flank­ ing this are paired postfrontaliaj prefrontalla, present in many species of the genus, have not been seen In T. stolli. Four pairs of dorsocentralia are situated In longitudinal rows posterior to the postfrontalia. Later­ al to these, extending In longitudinal rows posteriorly from the eyes, are four pairs of dorsolateralia, also without setae or pores. 77 Plates of the second type, with setae but lacking gland-pores, comprise two pairs which are situated between the eyes and the postfrontalia. These are known as the pre- and postocularia. The remaining plates, bearing both setae and gland- pores, are referred to as glandularla. The dorsoglandu- laria consist of six pairs. The first pair is situated anterior to the preocularia (these are also known as antenniform bristles). Pairs two to six occur in an irregular row between the dorsocentralia and the dorso­ lateralia. The lateroglandularia, four pairs in number, are arranged along the lateral margins of the dorsum. The ventral epimera are arranged in four groups of two each (Fig. 78). Epimera I and II are widely separated from III and IV. Between the two groups Is situated a pair of prominent coxoglandularia. Setal patterns of the epimera vary among individuals. The genital apparatus is situated at the level of epimera IV, but this position may be readily distorted in mounting. Characteristics of the palp of T. stolli are shown in Figures 79 and 80. The typical arrangement of palpal setae is shown in Figure 79. The extensor surface of P-l bears two small setae; the extensor surface of P-2 bears four setae. A variant Is shown in Figure 80 in which P-l bears a single large seta on its extensor surface, while P-2 bears five setae. It has not been possible to corre­ late this variation with other morphological characteris­ tics. In fact, individuals have been examined in which the right and left palps differ in the number of setae on P-l. The figure with the original description (Koenike, 1895: Pig. 32) shows two setae on P-l. Characteristics of the genital apparatus will differentiate the sexes (Pigs. 81, 82). The genital plates of females are larger and more rounded than those of males. The genital plates of males bear a more exten­ sive row of marginal setae than do the plates of females.

A prominent aedeagus (Pig. 8 3 ) is recognizable under the genital plates of males. Males and females do not differ significantly in size. Fourteen males and an equal number of females averaged l.llj. mm. and 1.13 mm. in length respectively.

Nymph. Both laboratory reared and field collected nymphs have been examined in the course of this study. The laboratory reared nymphs hatched directly from eggs without an intervening free larval stage. Except for differences in total body size, there have been no con­ stant morphological differences noted between field col­ lected and laboratory reared nymphs. 79 Characteristics of a laboratory hatched nymph are shown in Figures 81+-86. Sclerites of the dorsum (Fig.

8if.) are fewer in number than those of the adult. The ventral epimera are arranged in four groups of two each (Fig. 85)• Epimera II and III are close together in the nymph, whereas they are separated in the adult. Eplmeral setae are fewer in number in nymphs than in adults, epimera T bearing two setae and epimera III and IV each bearing one. The palpal trochanter, P-l, bears a single seta on its extensor surface in both field

collected and laboratory hatched nymphs (Fig. 8 6 ). Eight field collected nymphs averaged 0.93 mm. In body length, exclusive of the gnathosoma. An equal number of hatched nymphs averaged 0.3i6 mm. In body length.

Larva. Several clutches of eggs laid in rearing chambers yielded typical larvae. One of these is illustrated in Figure 87. Epimera I of the larva bear two setae and epimera III bear one as in the nymph. Irregular rows of five setae flank the mid-ventral line. Behind epimeron III on each are two setae, one of them marginal In location. A prominent coxoglandularial seta occurs behind epimeron II. Eggs. Eggs of two sizes have been laid In culture by females of this species. A female taken on 2 May, 195*f-» Ashland Co. (R16WT23NS11) laid eggs averaging O.lij.2 mm. in diameter

in four masses numbering 7k> 5 9 , *i3 > and two eggs be­ tween 9 May and 13 May, 195*1 (Fig. 8 8 ). Subsequently additional eggs were laid singly and in clutches of three to five eggs . Another group of eight mites collected by the writer

in Wayne Co. (R13WT17NS33) on 9 May, 195*^ deposited 12 masses varying from two to six eggs (average four) affixed to Sphagnum leaves (Pig. 89). These eggs averaged 0.2*i mm. in diameter.

Developmental ob servations. Eggs of the first type described, smaller in size than the others, hatched into larvae as described above. Additional females of Thyas stolli collected in Wayne Co. in 195*1 by tk® writer and in 1957 by Dr. C. E. Venard have deposited large masses of eggs whieh yielded larvae in 15 to 21 days following deposition. The larger eggs on hatching yielded nymphs as described above. Minimum hatching time for these indi­ viduals was seven days following deposition. 81 As previously indicated, the adults by which these two types of eggs have been produced are morphologically indistinguishable. It is to be hoped that further infor­ mation may explain this phenomenon. On and 27 June and 13 July, 1955* three infest­ ed mosquitoes were collected in Wayne Co. Two of these have been identified as Aedes vexans, the other as Aedes sp. by Dr. C. E. Venard. These harbored water mite lar­ vae which are identical with laboratory hatched larvae of Thyas stolli.

IV. FAMILY HYDRYPHANTIDAE

The family Hydryphantidae, as restricted by Viets (1936:125, 1956:131), is represented in North America by

Hydryphantes Koch, l8i|.l. Mitchell (195^36) lists three species for North America: H. multiporus Marshall, 1930? H. ruber Geer, 1776 (sic, apparently meant to be 1778)j and H. tenuabilis Marshall, 1926. Viets (1956:137) has synonymized H. tenuabilis with H. ramosus Daday, 1905- He (Viets, 1956:llj.O) also lists H. scaber (Haldeman,

I8I4.2 ) as a species inquirenda. Lundblad (1938:7) appar­ ently considered H. tenuabilis a synonym of H. ramosus. The hydryphantids are deep red mites, common in the springtime in standing water with much organic debris. The genus Hydryphantes is characterized by a prominent 82 anterior dorsal sclerite in which the frontal organ is situated. The shape of this plate has been the chief basis for species separation. Legs II, III, and IV bear numerous long swimming hairs. The writer * a collections have yielded two species of this genus. One of these is Hydryphantes ruber; the other is presented as a new species.

Hydryphantes ruber (Geer, 1778) This is a holarctic species which has been re­ corded throughout Europe and Asia (Viets, 1958:139); and in Canada, Ohio, Michigan, Illinois, Wisconsin, and Wyoming (Marshall, 191+6:360). I have collected this species In North Carolina. The present study Includes specimens from five Ohio counties: .Ashland (R16WT23NS11), Fairfield (R18WT17NS32), Licking (Rlij.WT3®S7), Lorain (Huntington Twnp.), and seven townships in Wayne Co. This species was collected only between 11 March and 3 May in 1952, 1951]-, 1955, and 1956. Identification of this species by the writer has been based on comparison with specimens loaned by the Chicago Natural History Museum. The loaned material was collected 23 March, 1927, Third Sister Lake, Michigan by "Welch." 8.3

Adult. The shape of the dorsal shield and charac­ teristics of the palpi are common to both sexes of Hydry- phantes ruber (Pigs. 90 and 91). The plate is slightly broader anteriorly than posteriorly. The anterior margin of the plate shows a slightly rounded, convex outline. Its posterior margin bears laterally situated, posterior­ ly directed prolongations. The shallow bay between these

posterior projections is less than l/8th of the length of the plate measured along the midline. The frontal organ is situated in the raidline a slight distance behind the anterior margin. Prominent setae are present at the anterior and posterior corners of the plate. A pair of glandularia flanks the plate opposite lateral emargina­ tions . The palpus bears setae on its extensor surface as indicated in Figure 91. P-2 bears a prominent seta on its medial surface. Males and females differ In size and In character­ istics of the genitalia. Twenty-two females In the

writer's collection vary in length from l.lf? to 2.02 mm.

(average l .£7 mm. ); twenty-one males vary from 0.96 to 1.92 mm. (average 1.30 mm.). The genital apparatus of the female is shown in Figure 92; that of the male in Figure 93. Each consists of a pair of hinged, movable 81*. plates with three pairs of acetabula. Plates of the male are somewhat angular while those of the female are more rounded.

Nymph. Twenty-one nymphs in the writer*a collec­

tion vary from 0.86 mm. to l.i|4 mm. in body length (average l.li*. mra. ). The frontal shield of the nymph is similar in outline to that of adults, and bears similar setae (Pig. 9h)* The frontal organ is proportionately larger in nymphs than in adults, and is somewhat farther removed from the anterior margin of the shield. The provisional genitalia consist of two pairs of acetabula, with curved plates between the pairs {Fig. 95).

Larva. Fifteen laboratory hatched larvae of Eydry- phantes ruber vary from 0.180 mm. to 0.270 ram. in total length, the average being 0.229 mm. The gnathosoma com­ prises slightly more than 1/3 of that length. The venter shows three pairs of incompletely sclerotized epimera (Fig. 96). A prominent glandular selerite is noted be­ tween epimera I and II. The setal pattern shown in

Figure 96 appears to be constant.

Eggs. Eggs of this species are regularly laid in large clutches. Nine clutches examined contained an esti­ mated 60 to 1914. eggs, averaging slightly over 100 eggs 85 per clutch. Two females In the collection continued to deposit eggs In lesser numbers for a few days following deposition of their first large masses. Figure 97 shows one of these smaller masses. The color of an entire egg mass is reddish-orange (Red, 5*0 R 5/12 of Munsell, 1929). The eggs are laid in thin sheets stacked upon one another. Each egg is separately encapsulated in a gelatinous cover.

Developmental observations. Six clutches of eggs observed in rearing chambers showed minimum hatching time from 11 to 16 days following deposition. Many newly hatched larvae came Immediately to the surface and could be seen moving rapidly above the surface film. On 1 May, 1956, a clutch of eggs which had been collected four days earlier was observed to have numerous active larvae within the gelatinous capsule covering the mass. While under observation one mite was noted in movements which led to escape from the capsule. These movements began with puncturing of the capsule by the gnathosoma, which was then protruded. Bext, right leg I was extended through the slit, followed In order by left leg I and left leg II. After a brief struggle, the re­ mainder of the body slipped out in a single Tunge. The whole process took place in an elapsed time of three and one-half minutes. 86 The host of H. ruber in Ohio is not known. Viets (1936:^-99) indicates that they parasitize Culex and Caenia. Several attempts by the writer to Infest mosqui­ toes with larvae of this species have been unsuccessful. In all, 523 Aedea aegypti and 77 Culex piplens have been exposed unsuccessfully.

Hydryphantes waynensia, n. sp. Diagnosis. Hydryphantids with characteristics of the genus Hydryphantea. Dorsal sclerite with posterior bay equal in depth to 3/k the length of the plate along the midline. Two setae on medial surface of P-2. Three pairs of genital acetabula present.

Twenty-three specimens in the writer’s collection represent a previously undescribed species for which the name Hydryphante3 waynensis is proposed. All specimens of this species were collected in Wayne Co., Ohio. Four­ teen of the twenty-three specimens were collected in Brown’s Lake (Rlij.WTl8NS21). The remaining specimens were collected in three other locations: R11WT18NS18 (Chippe­ wa Twnp.); RI3WTH4HS2O (Franklin Twnp.}, and R13WT15NS31 (Wooster Twnp.). All collections were made in standing water with much emergent vegetation. 87 The earliest seasonal collection of H. waynenais was made on 11 March, 195i+» and the latest on 16 May, 195^* All collections were made in the spring of 1952 and of 1954-- A single specimen, collected on 16 May,

195^4-* waa on that date placed in a refrigerator in a closed jar with other organisms. This was overlooked for several months and on 15 Mareh, 1955* it was re­ opened. At this time the mite was active and remained so until 15 April, 1955* on which date it was dead.

Adult. Hydryphantes waynensis is a small mite compared to most (but not all) other species of the genus. The nine males in my collection average 0.97 aim* in body length (0.82 to 1.10 mm.). The twelve females in my collection average 1.27 mm. In length (1.10 to 1.73 mm.). The dorsal sclerite of H. waynensls exhibits a deep bay between its posterior prolongations (Pig. 98). This bay is equal in depth to about 3/lf. the length of the plate along the midline. The anterior corners of the frontal shield are broadly attenuate and bear two pairs of prominent setae. Characteristics of the adult palpus are shown in Figure 99. Significant in the recognition of this form is the presence of two setae on the medial surface of P-2. 88 The sexes differ only slightly in characteristics of the external genitalia. The genital apparatus of fe­ males (Pig. 100) is slightly shorter and narrower than that of males (Pig. 101). Setae on the medial margin of the genital plates are fewer in number, and somewhat stouter in males than in females.

Nymph. The writer’s collection contains two nymphs of H. waynensis. These specimens measure 0.861}. mm. and 0.912 mm. respectively. The dorsal shield (Pig.

102) shows an outline similar in proportions to that of the adult. The frontal organ is proportionately larger in the nymph than in the adult. Antero-lateral projec­ tions of the shield possess only a single pair of setae. The provisional genitalia of H. waynensis show two pairs of acetabula. As in other species of the genus there is a sclerotized plate between the acetabula of each side (Pig. 103). Only two setae are seen on the medial margins of these plates.

Larva. Twelve laboratory hatched larvae of H. waynensis average 0.171}. mm. (0.153 to 0.225 mm.) in length including the gnat ho soma (Pig. 101|_). The gnatho- soma comprises approximately 1/3 of the total length. Epimera I and II are incomplete medially. Setae are distributed as shown in Pig. IGi}.. 89

Eggs. A female of this species deposited two clutches of eggs on 29 April, 1951+. The clutch illustrat­ ed (Pig. 105) contained 33 eggs, individually encapsulated and arranged in a single sheet and a larger clutch con­ tained an estimated 110-120 eggs. A note made at that time indicates their color as "bright orange."

Developmental observations. Daily observations of eggs in culture show that first hatching occurred in eleven days following deposition. At 19 days less than half of the total mass had hatched and the remainder appeared to be dead. Larvae remained active for ten days following hatching. These larvae moved rapidly across the sur­ face of the water with a springing motion. Adults of H. waynensis were frequently observed crawling about the walls of the rearing chamber and on its cover, completely out of the water. If replaced in the water, the mites swam actively again. The significance of this pattern of behavior is not understood at the present time.

Comparisons. Hydryphantes waynensis can be distin­ guished from other species of the genus by the shape of its frontal shield and the number of setae thereon, and 90 by characteristics of tlae palp. It differs from H. ruber in possessing a shield with a deeper posterior bay, more attenuated antero-lateral projections and the presence of two pairs of setae on these projections, there being only one pair in H. ruber. P-2 of H. waynensis bears two setae on its medial surface compared to one in H. ruber. The frontal shield of H. waynensis is similar in outline to that of H. abnormls Koenike, 1908, and H. placa- tionis Thon, 1899» but differs from both of these species in the presence of two pairs of setae on its antero­ lateral corners. The frontal shield is also similar in outline to that of H. multiporus Marshall, 1926, and H. microphallus Lundblad, 1 9 but differs from these species In having only three pairs of genital acetabula.

Type material. Hoiotype and paratypes of this species will be deposited In the Chicago Natural History Museum. Paratypes will also be deposited In the Ohio State University Entomology Museum and others will be retained In the writer’s collection. 91

V. FAMILY HYDRODROMIDAE

Hydrodroma despiclens (Mttller, 1776) The family Hydrodromidae is represented in the writer’s Ohio material by 32 specimens of Hydrodroma desplciens (-Diplodontus despiclens) collected on 7 and 8 August, 19£6, in a farm pond on the Ohio State Univer­ sity campus (Franklin Co.,Clinton Twnp.). The collections include 17 males, 12 females, and three nymphs. In addition I have larvae hatched from eggs laid by a female from this locality. The determination is based on comparison with ma­ terial previously concluded to be identical with speci­ mens of Hydrodroma despiclens collected by R. H. Wolcott on 28 August, 1908,In Pelican Lake, Minn., and loaned to me by the Chicago Natural History Museum. This Is a truly cosmopolitan species, being record­ ed from every continent except the Arctic and Antarctic (Viets, 1956:lf?0). There had been some question of Its occurrence in Australia until Lundblad (19lj-713lp) reported its collection in Tasmania. Marshall (19i+6:362) notes its occurrence ,fin about half the states in the Union. ” Ten years earlier she (Marshall, 1936:133) reported this species from cenotes of Yucatan. Hoff (19i}4s50) records 92 the species In small numbers from Reelfoot Lake, Tenn. The writer has collected the species in Durham Co., North Carolina. Marshall (1929c!69) reports H. desplciens from four localities in Canada. Mitchell (195>!|) lists two species for North Ameri­ ca, the other being H. amerlcanus Marshall, 1926. Both Marshall (1929c:69) and Viets (1956:114.9) have considered 5* amorlcanus synonymous with H. despiclens. This species is typically found in standing water with much aquatic vegetation. Though of wide distribution and common occurrence, it is seldom found in large numbers. Specimens cheeked while living against Munsell (1929) color standards were nyellowish Yellow-Red,rt (7*5 YR 7/8). Colors from yellow, to red, to dark brown are recorded in the literature (Soar and Williamson, 1925:161).

Adult. The 12 females in this collection ranged from 0 .86I4- to I.632 mm. in body length, averaging 1.176 ram. Sixteen males varied from 0.7&8 to 1.632 mm. in length and averaged 1.266 mm. Most reports in the litera­ ture indicate the male slightly smaller than the female. The ventral epimera of H. despiclens are arranged in four groups of two each (Pig. 106). A wide area of non-sclerotized integument separates the propodosomal and 93 metapodosomal epimera. The area occupied by the epiinera is a relatively small portion of the total ventral surface. The propodosomal epimera are joined weakly in the midline. Each epimeron bears a fringe of long setae along its pos­ terior margin. Epiinera I have a few setae along the an­ terior margin. Epimera I, II, and III bear clusters of setae at their lateral ends. Prominent glandular setae are situated behind epimera II and IV. This species is readily recognized by the relation­ ship of palpal segments I4. and 5* The distal end of the penultimate segment Is extended into a long tapering pro­ cess which forms a delicate chela with the terminal segment (Pig. 107). The genital apparatus is situated between epimera IV. External genitalia of the two sexes show only minor differences. The genital plates of females (Pig. 108) are slightly smaller than those of males (Pig. 109). An­ teriorly the plates of males taper slightly more than do those of females. Genital plates of both sexes bear numer­ ous small acetabula, up to £0 or more per plate. Males in the writer*s collection have been readily recognized by the presence of a sclerotized aedeagus (Pig. 110). The integument of H. despiciens is soft and non- sclerotized, and possesses papillae. The eyes of each 91+ side are distinctly separated (Fig. 111). These two characteristics are common to all species of the genus Hydrodroma as characterized by Wolcott (1905il88).

Nymph. Nymphs of H. despiciens are few in number in my Ohio collections, there being only three specimens.

These vary in length from O.38I+ mm. to 0.720 mm., averag­ ing 0.560 mm. The ventral epimera are arranged, as in the adult, in four epimeral groups (Fig. 112). The suture separating epimera X and II extends about half way across the epimer­ al group. The propodosomal epimera are widely separated in the midline. Epimeral setae are fewer in number in the nymph than in the adult, and are situated on the lateral margins of the epimera. The provisional genitalia consist of two pairs of distinctly separated acetabula. These are free in the integument. An excretory pore Is located,in the midline poster­ ior to the genitalia. The nymphal palp shows a characteristic chela simi­ lar to that of the adult (Fig. 113)- The palpal genu, P-3> bears a pilose seta on its medial surface and a large, simple seta on its extensor surface. 95

Larva. A series of ten laboratory hatched larvae of H. despiciens averaged 0.202 mm., the individuals vary­ ing from 0.191 to 0.225 mm. in length, including the gna- thosoma but exclusive of the palpus. The epimera of the larva are distinct and widely separated medially (Pig. lilt) * Epimera X and III each bear a single simple seta. Between epimera I and II and between II and III, near the body margins, are prominent coxoglandularia. Three pairs of ventral setae and two pairs of marginal setae are distributed in the post- epimeral area of the Integument.

Eggs. A clutch of 26 eggs laid by a female of this species Is illustrated in Figure 115* The eggs were arranged in a single layer, closely packed together, and with a gelatinous capsule over all. The color of these eggs compared with Munsell (1929) standards was yellowish Yellow-Bed (7*5 R 7/l0). The capsular material has a slightly granulated appearance. Observations of these eggs were so spaced that pre­ cise hatching time cannot be stated. However the range of possibility is seven to ten days of incubation follow­ ing deposition. 96

VI. FAMILY LEBERTIIDAE

Collections from rubble beaches and rocky bottom

areas in the Bass Island archipelago and along the south

shores of Lake Erie have yielded numerous nymphs and adults

of the genus Lebertia. These specimens represent a single

species, which is identical with specimens of Lebertia

poroaa loaned by the Chicago Natural History Museum. The

museum specimens were collected in "Big Telephone Brook,

Wyoming, (by) J. W. Scott." The genus contains numerous species and varieties, there being more than 250 listed by Viets (1956). Twelve of these have been recorded from North American by Mitchell (1954)-

Lebertia porosa Thor, 1900 L. porosa is a holarctic species (Viets, 1956:203). It has been collected across Canada (Marshall, 1929c:70), in Alaska, and nine states in the United States (Marshall, 1932:^0). The species has been collected by the writer in

the following localities: Cuyahoga Co., Bay Village;

Erie Co., Kelley*s Island and Huron; Lorain Co., Lorain; and Ottawa Co., Middle Bass and South Bass Islands. All collections were on rubble beaches along Lake Erie except 97 those of South Bass Island, where the species was taken from rocky bottom areas of Put-ln-Bay and the adjoining Terwilligar*s Pond. All collections were made in June, July, and August, 195il* Numerous specimens of L. porosa collected in various localities in Put-in-Bay have been transmitted to the writer by Mr. Louis Garrick, Department of Biology, Wayne University, One specimen which Mr. Carrlck removed from the gastrovascular cavity of Hydra littoralis on 25 June, 195i|-» Is a nymph of this species.

Adult. L. porosa exhibits little sexual dimorphism externally, but males can be recognized by the presence of a sclerotized aedeagus within the external genital appara­ tus. Ten males in the writer's collection average 0.829 mm. in length, ranging from 0.768 to 0.912 ram. Females average slightly larger. Twenty-seven females vary from

0.627 mm. to 1.152 mm. in body length, averaging 0.86? mm. The epimera of L. porosa cover portions of the ven­ tral surface ranging from nearly all In males to less than half in gravid females, this proportion being related to the state of distention of the body. Epimera I are separated from epimera II by a distinct suture (Fig. 116). Epimera I of the two sides are completely fused, there be­ ing no evidence of a medial suture. Epimera II, III, and IV of each side are Incompletely fused. A suture beginning 98 medially and extending slightly less than half the dis­

tance to the lateral margin is present between epimera

II and III. Epimera III and IV are partially separated

by a suture which begins laterally and extends about two-

thirds of the distance toward the medial margin. Epimera

II of the two sides form a prominent suture medially.

Posterior medial angles of the fourth epimera are gent­

ly rounded. A short but prominent seta is borne on

this angle.

The genital apparatus lies in a bay formed by the posterior medial margins of epimera II, III, and IV.

The fourth epimera reach a level which includes about two-thirds of the length of the genitalia.

Members of the subgenus Pilolebertia, which in­ cludes Lebertia porosa, are characterized by the pre­ sence of "numerous'* swimming hairs on legs II-IV and es­ pecially on podomeres III-5 and IV-5- My Lake Erie specimens fall within the range for L. porosa given by

Viets (1936:178) for this characteristic: III-5» 8-15 swimming hairs; IV-5, 8-17 swimming hairs.

The palpus of L. porosa bears five long, pilose setae on the medial surface of P-3 (Fig. 117)- Viets

(1936:171) refers to these setae according to the fol­ lowing scheme: The three near the distal end of P-3 are 99 called dorsal, inner, and ventral distal setae (Haaren). That closest to P-2 is called the proximal seta. The remaining seta (or setae) is designated the middle seta. The position of these setae, in combination with the de­ gree of fusion and posterior extent of the epimera, serve to separate this species from others of the genus.

Nymph. Numerous nymphs of L. porosa have been taken in the present collections. These nymphs vary from 0.1+80 mm. to 0.720 ram. in body length, averaging 0.571+ aim. The ventral epimera of the nymph (Pig. 118) exhi­ bit a pattern similar to that of the adult. The suture separating epimera I and II is incomplete medially. The provisional genitalia consist of two pairs of aoetabula on a single rounded plate. The acetabula are surrounded by a sclerotized ring. The palpus of the nymph has proportions similar to that of the adult, but bears fewer setae (Pig. 119).

Developmental observations. On 29 June, 19Sh* collections of bottom fauna from a rubble beach on Middle Bass Island yielded a caddis worm case containing six individuals of I». porosa. One of these was an adult and possessed a prominent red spot located medially on the 100 dorsum. The remaining three specimens proved to be imagochrysallds of this species, with developing adults already clearly visible within. The adult and one nymph were subsequently mounted and the other nymph and the imagochrysallds retained in rearing chambers. By 9 July, 1 9 5 fcke nymph had entered the imagochrysalid stage and an adult had emerged from one of the original imagochrys­ allds. By this date the imagochrysallds were cloudy and opaque. Subsequent observations were too widely spaced to determine the developmental time precisely. However, by 9 August, the last imagochrysalid had yielded an adult making the maximum time in the imagochrysalid stage 30 days.

VII. FAMILY TORRENTICOLIDAE

Two species of the genus Torrent!cola (~Atract- ides), family Torrenticolidae, are represented in the writer* a collection from Middle Bass Island and Put-in- Bay. One of these species is Torrentlcola (Rusetria) Indiatineta (Marshall, 1929a). The other species, pre­ viously undescribed, is of the subgenus Torrentlcola. Members of the genus Torrentlcola are characterized by the presence of large dorsal and ventral sclerites plus two pairs of smaller sclerites located antero-aorsally. 101 The subgenera, of which Viets (1956) recognizes four, are separated on the basis of the degree of fusion of the small anterior dorsal plates to each other or to the larger dorsal plate. Mitchell (1954) records 14 species of the genus from North America. It is of interest to note that none of the species of nearctic occurrence have been reported outside that region, nor have species from other regions been recorded within the nearctic region. Only two species, T. Indistlncta and T. .lordanensis (Marshall, 1930) have been recorded from east of the Mississippi River.

Torrentlcola lndlstincta (Marshall, 1929a) Ten specimens of this uncommon species were col­ lected during June and July, 1954* from rubble beaches and rocky bottom areas of Put-in-Bay and Middle Bass Island. The species was originally described by Marshall from a single specimen taken In Lake Wawasee, Indiana, though she noted in the description that the species had also been found In Wisconsin (Marshall, 1929a:319). Sub­ sequently she (Marshall, 1932:342) recorded the species from Green and Winnebago Lakes in Wisconsin. The writer 102 has examined material of this species collected by ”Juday, July, 1921, Green Lake, Wisconsin; detr. Marshall.” This material was provided by the Chicago Natural History Museum. The body of this species is oval in outline, and the ten specimens averaged 0.72? mm. long, measured from the anterior tip of the epimera to the posterior margin of the body. The range of body length is from 0.576 mra. to 0.816 mm. The first epimera extend well forward be­ yond the limits of the remainder of the body. T. Indistincta is characterized by nearly complete fusion of the lateral pair of anterior dorsal plates usually seen in this genus with the large dorsal plate (Pig. 120). The integument is heavily solerotized and highly sculptured. Finely granulated areas are to be noted on the dorsal surface near the midline, slightly behind the middle of the body. The epimera are closely joined to each other and to the general integument (Pig. 121). Epimera I are com­ pletely fused medially and in the female reach to the genital area posteriorly. Marshall (1932:3^2) has noted that epimera I of males do not reach the genital area. A suture which is incomplete medially, extending only about half way from the lateral margin toward the midline, marks 103 the division between epimera I and II. The fourth epimera are indistlnguishably fused with the ventral integument.

The genitalia are completely surrounded posterior­ ly with highly sclerotized integument. The palpus of T. indistlncta Is Illustrated in Figure 122. P-2 and P-3 bear well developed processes on the Inner surface, distally. On the process of P-2 and near the process of P-3 arise elongate simple setae. P-I4. bears a cluster of fine setae arising from a low papilla on the flexor surface.

Torrentlcola bittikoferae,n. sp. Diagnosis. Torrentlcolida with characteristics of the genus Torrentlcola (s. s.). Anterior dorsal plates four in number. Setae of flexor surface of P-lj. not on papilla. P-lj. not appearing inflated.

Sixty-seven specimens of Torrentlcola, collected In June and July, 195k* on rubble beaches and rocky bottoms of Middle Bass Island and Put-in-Bay, represent a previously undescribed species. This species is dedi­ cated In name to Miss Lelia Bittikofer, teacher in Sandus­ ky, Ohio, High School, who Introduced the writer to the formal study of biology In the geographical area where these specimens were collected. 1014. Twenty specimens of T. bittikoferae average 0.821 mm. in body length measured from the anterior tip of the first epimera to the posterior margin of the body and are nearly circular in outline. The range of body length is from 0.720 mm. to 0.912 mm. This species is among the larger nearctic forms of the genus, being exceeded in size by only three species described by Marshall (19ij-3&) from California, viz. T. californica, T. geographics, and waddellica, and by T. jordanensis (Marshall, 1930) from Wisconsin. The possession of four distinctly separate anter­ ior dorsal sclerites (Pig. 123) places this species in the subgenus Torrenticola. The medial pair is about two- thirds the length of the lateral pair. Each sclerite shows a finely granular area near its posterior-medial corner. Similar paired granular areas are present in the large dorsal plate, near the midline at the middle of the body length. The Integument is highly sclerotized and finely sculptured. Large, porelike openings may be noted among the finer markings. A single such pore is present on each medial anterior sclerite and two occur on each lateral anterior sclerite. Two pairs are noted in the larger dorsal sclerite, as shown in Figure 123*

The ventral epimera (Pig. I2I4.) are somewhat less compactly arranged than in T. indlstlncta. Epimera I are 105 broad and medially fused. They do not reach the genital apparatus but are separated from it by non-sclerotized integument rather than by epimeral groups II-III. Su­ tures between epimera I and II and between III and IV widen medially showing some non-sclerotized integument. A similar non-sclerotlzed area partially separates epi­ mera XV medially from the post-epimeral sclerotized In­ tegument. A short, Indistinct suture begins laterally between epimera II and III, but extends less than one- sixth of the distance across the epimeral group. Three pairs of large pores are situated in the fourth epimera and post-genital area. An excretory pore surrounded by a sclerotized ring is present in the vent­ ral midline posterior to the genital apparatus. The palpus of T. bittikoferae is elongate as In most other species of the genus (Pig. 125)• P-2 and P-3 each bear a process on the flexor surface of the distal end, and each process bears a single seta. P-Lj. Is dis­ tinctive, however, in that the setae of the flexor sur­ face are not borne on a papilla.

Comparisons. Torrentlcola bittikoferae may be distinguished from other species of the genus by charac­ teristics of the palpus. In the fact that the setae of P-i*. are not on a papilla, T. bittikoferae differs from 106 all nearctic species except T. californlca (Marshall, 19i]-3a) and T. oblongata (Marshall, 19i|3a)» However, the palpi of these species differ from T. bittikoferae in proportions. P-Ij. of T. californica appears somewhat in- lated. The palpus of T.oblongata is shorter and stouter than that of T. bittikoferae. Prom both, T. bittikoferae differs in size, body shape, and proportions of the epi­ mera. It is smaller than T. californica and larger than T. oblongata. Prom the other two species recorded from the Great Lakes basin T. bittikoferae can be distinguished by characteristics of the anterior dorsal plates. The later­ al pair is almost indlstinguishably fused to the large dorsal plate in T. indistincta, which differs from the four distinct plates of T. bittikof erae. T. .lordanensis possesses four distinct anterior dorsal sclerites but the medial plates are about two-thirds the size of the lateral plates in T. bittikoferae. The medial plates are about one-third the size of the lateral plates in T. .lor- danensls.

Type material. Holotype and paratypes of T. bittikoferae will be deposited in the Chicago Natural History Museum. Paratypes will be placed in the Ohio State University Entomology Museum and others will be retained in the writer's collection. 107

VIII. FAMILY LIKNESIIDAE

The family Limnesiidae is represented in this sur­ vey by numerous specimens of Limnesla undulata and by seven specimens of a different but undeterminable form taken in two localities in Wayne Co., and a single unde­ terminable specimen from Buckeye Lake.

Limnesia undulata (MfHler, 1776) undulata is undoubtedly of widespread occurrence throughout the holarctic region and has been recorded from Africa and South America (Viets, 1956:2814.). The species is closely related to L. fulglda Koch, 1836 from which it is distinguished only with difficulty (Marshall, 1932: 3kS). Hoff (19l4l(.:60) has discussed this situation and points out that because of the confusion it is impossible to review the locality records with certainty. It has been unquestionably reported from Wisconsin (Marshall, loc. cit.) and from Tennessee (Hoff, loc. oit.). The writer has material of this species from North Carolina, and in the present survey it has been collected by the writer in Buckeye Lake, Licking Co., In a private lake In Wayne Co. (R11WT18NS17)» ana in Put-In-Bay and adjoin­ ing Terwilligar»s Pond in Ottawa Co. Dr. A. G-. McQuate, Heidelberg College, Tiffin, Ohio, has given to the writer specimens of this species taken at Winous Point in Sandusky Bay. Two Ohio records may be mentioned here, which be­ cause of the taxonomic confusion referred to above, must remain in doubt. Shelford and Boesel (19^2) listed L. undulata among the bottom fauna taken in the island area of Lake Erie. Miller (192£;123) lists from Buckeye Lake L. histrionioa var. wolcotti which is now considered a synonym of L. fulgida (see Viets, 19^6:271+) • The two species in question, L. undulata and L. fulgida can be separated on the basis of the degree of fusion of epimera I medially (Viets, 1936:2JL|.8; Hoff, 19i4j-i60). In 1^ undulata the first epimera are complete­ ly fused; in L. fulgida the first epimera join, but a suture of varying prominence remains.

Adult.. Twenty males in the present collection average 1.27 mm. in body length and 20 females average 1.20 mm. in body length. The range of body length for the males is 1.06 mm. to 1.73 mm.; that for the females is 0.768 mm. to I .63 mm. The epimera as indicated above, are characterized by the complete fusion of epimera I in the midline (Pig. 126). The metapodosomal epimera of 109 each side form a plate of roughly triangular outline.

Epimera III and IV are separated by an irregular suture which is incomplete medially.

The external genitalia lie between epimera IV. In both sexes the apparatus consists of paired plates, each with three large acetabula. The genital plates of the male (Fig. 127) are somewhat more rounded and more seta­ ceous than those of the female (Fig. 128).

The palpus of L. undulata Is characterized by the presence of an elongate process on the flexor surface of P-2, which in turn bears a short, stout, toothlike peg (Fig. 9). The extensor surface of this podomere bears a variable number of short setae arranged in two rows.

Nymph. Several nymphs of this species have been collected at Put-In-Bay and Terwilligar*s Pond. Twenty of these averaged 0.619 mm. In body length, ranging from 0.528 mm. to 0.768 mm.

The epimera of the nymph are similar In arrange­ ment to those of the adult, except that epimera I are not united medially (Fig. 129). The provisional genitalia consist of four acetabula on a single plate. Medially between the posterior acetabula Is a cluster of small, stout spines. 110 Palpal segment two (Pig. 130) lacks the process and peg characteristic of the adult. Shorter setae of the extensor surface of adult P-2 are likewise wanting in the nymph. A single nymph of this species was reared from a midge of the species Tendlpes (Tendipes) decorus col­ lected on Gibraltar Island on 6 July, 195^-*

Larva. The larva of L. undulata has not been ob­ served by the writer. According to Soar and Williamson (1925:23) Neuman, Piersig, and Musselius have indicated that L. undulata has no free larval stage, but that the larval existence is passed under the protection of the gelatinous layer investing the eggs.

Eggs. A female collected In Sandusky Bay deposited the egg cluster shown in Figure 131, between 2 July and 6 July, 195il* These were observed periodically through­ out the subsequent fall and winter, but did not hatch. By 28 March, 1955» the clutch had disintegrated and the culture was discontinued.

IX. FAMILY HYGROBATIDAE

My collections of Ohio mites contain 89 specimens of the family Hygrobatidae, which are assigned to the Ill species Hygrobates longlpalpls. This species has been recorded from Europe, Asia, Africa, and North America (Viets, 1956s310)- In Canada it has been reported from British Columbia (Koenike, 1895:212) and from several locations in Ontario including Lake Ontario (Marshall,

1929c:75)• In the United States, Marshall (1932:347) has reported the species from ten states east of the Rocky Mountains and from California (1943^:412) . These records include Ohio, but without a precise location within the state. The writer*s material has been collected from North, Middle, and South Bass Islands in Ottawa Co., on Kelley*s Island and at Huron in Erie Co., at Lorain in Lorain Co., and at Bay Village in Cuyahoga Co. All col­ lections were made from rubble beaches and rocky bottom areas.

Hygrobates longipalpis (Hermann, 1804) Adult. Nineteen males in the collection varied from 0.576 mm. to 0.960 mm. in body length, averaging 0.664 mm. Females are slightly larger; 20 of these varied from 0.576 mm. to 1.104 mm., averaging O.78J4- mm. The ventral epimera are In three groups, epimera I of the two sides being completely fused medially and epi­ mera II joined with them (Fig. 132). The gnathosomal 112 plate Is fused with the propodosomal epimera. Epimera III and IV are fused and present a rounded, triangular outline. Epimeron III Is relatively'small; a suture separating it from epimeron IV is incomplete medially. The species is characterized, in part, by the rounded medial angle of epimera IV. Extra-epimeral areas of the integument are soft and flexible. Some individuals show an indication of fine striations. This is apparently cor­ related with the degree of distension of the body; gravid females, for example, show little indication of striatlon of the integument. The sexes may be differentiated by characteristics of the external genitalia. The genitalia consist of a pair of plates flanking the genital orifice each bearing three large acetabula and several fine setae. The paired plates of the male are joined by sclerotized bridges in front of and behind the orifice (Pig. 133). The genital plates of females lie free in the Integument (Pig. l£). H. longipalpis is distinguished in part by charac­ teristics of the palp (Pig. 13^4-) * The flexor surface of P-2 bears a prominent projection which is covered with many fine teeth. The medial surface of P-3 bears a patch of similar fine teeth. P-ij. possesses a cluster of elon­ gate, simple setae slightly beyond the mid-point on its 113 flexor surface. There is some variation in the number of setae in the cluster. Twenty specimens examined for this characteristic showed four with two setae, iLp with three setae, and two with four setae.

Nymph. The collection contains 20 nymph3 taken by- scrubbing rubble and by dragging the Birge net cone across rocky bottom areas. In addition there is one nymphal specimen removed from the gastra-vascular cavity of a specimen of Hydra littoralis collected 18 June, 1954* Put-in-Bay by Mr. Carrick. The hydra was collected just off the west end of Gibraltar Island.

Twenty of the nymphs average O.383 mm. in body length, varying from 0.288 mm. to 0.576 mm. The ventral epimera (Pig. 135) are more closely associated than in the adult. There is, for example, no non-sclerotized integument between epimera II and III as there Is in the adult. The suture between epimera III and IV is complete medially In the nymph, in contrast to the situation in the adult where it is incomplete. The gnathosomal plate is fused to the epimera as in the adult. The provisional genital apparatus consists of a pair of nearly oval plates, each of which bear two large acetabula and usually, but not invariably, three fine setae. 111+ The Integument of nymphs shows a pattern of fine striations. The palpus of the nymph of H. longlpalpis (Fig.

1 3 6 ) shows the process with fine teeth on P-2 and the patch of fine teeth on P-3 which are characteristic of the species as noted in describing the palpus of the adult. Likewise there is a cluster of elongate, simple setae on the flexor surface of P-l|., as in the adult. Setae of the extensor surface are fewer in number in the nymph than in the adult.

X. FAMILY PIONIDAE

The family Pionidae includes ten genera (Viets, 1956:263). Seven of these are recorded from North Ameri­ ca (Mitchell, 1951+:i+5 -14-6 ) . The writer’s Ohio material in­ cludes representatives of three genera: Tlphys (-Acercus), Fiona (=Curvipes), and (-Tiphys, in part). Of the genus Tiphys, I have six specimens of Tiphys torris var. amerioanus (Marshall, 1937) and several speci­ mens of what appears to be a new species. However the material, collected in Wayne Co., contains only two males, neither of which is complete. Inasmuch as males are essential to characterize the species of this genus, nam­ ing and description must await the acquisition of adequate material. H5 The genus Plona Is represented In my material by three species, one previously recorded from Ohio, one new to Ohio, and one to be described herein. The genus Forella is represented by five specimens from Terwilligar*s Pond on South Bass Island. This appears to be a new species, but the writer does not feel war­ ranted in basing a specific description upon this small sample.

Tiphys torrla var. amerioanus (Marshall, 1937) This variety of the cosmopolitan parent species was described by Marshall from specimens taken in Illinois and Wisconsin. The writer*s material was taken in two locations in Wayne .Co. (Plain Twnp., Rllj.WT19NS32, and Chippewa Twnp., R11WT18NS21) and in Licking Co. (Liberty

Twnp., RII4.WT3NS7 ) * These collections were made on 1 May, 195il» 18 April, 1955, and 27 April, 1956, respectively.

Four females in the collection range from O.86I4. mm. to 1 .10)4. mm., averaging 0.972 mm. in body length. Two males measure 0.768 mm. and 0.816 mm. averaging 0.792 mm. in length. These figures are slightly smaller than those stated by Marshall for the variety. The epimera cover nearly all the ventral surface in the male; in the female they cover a somewhat smaller 116 proportion of the venter. In both sexes the epimera are arranged in four groups of two each (Pig. 137). The medial ends of epimera I and II are produced into posteriorly directed projections,which may reach the anterior margins of epimera III. Epimera III and IV are joined with a com­ plete suture. An elongate glandular seta is present in the non-sclerotized integument between epimera II and III of each side. Other glandular setae may be seen behind epimeron IV, one lateral to the posterior angle of the epimeron and one medial to the epimeron, between it and the genitalia. On the anterior margin of the body a single pair of antenniform bristles is present. Marshall (1937:237) points this out as a feature distinguishing this variety from the parent species which possesses two pairs of antenniform bristles. The female genitalia consist of paired genital plates, roughly triangular In form and bearing three ace­ tabula and a few long, fine setae (Pig. 137). The geni­ tal plates and orifice are of approximately the sans length. The genitalia of the male consist of larger plates joined by a sclerotized bridge before and after the genital orifice (Pig. 138)• Three genital acetabula are present on each side; long, fine setae have been seen 117 adjacent to, but not on the plates. Epimera IV of the male form a broad, shallow bay partially enclosing the genital apparatus. Legs II-IV bear swimming hairs. Sexual dimorphism of the legs is marked. In males legs III are notably shorter than the others. Leg IV is peculiarly modified in this genus, as shown in Figure 139. Podomere IV-ij. presents a broad, flattened appearance with numerous long setae on its margins and in this variety, two stout spines are distally located on Its ventral surface. Podomere IV- 5 Is slightly curved and distally it bears a spur, armed with a stout peg.

The palpi of T. torris var. americanus (Figs. II4.0 and li|JL} are somewhat slimmer than those of the parent species (Marshall, 1937:237). Palpal segment four bears small papillae midway on the flexor surface, from which two fine setae arise. A stout peg is seen distally on the medial surface of P-I4.. A fine seta on the extensor surface of P-l In the male has hot been seen on P-l of the female.

Piona rotunda (Kramer, 1879) Fiona rotunda is of wide occurrence, having been reported from Europe, Asia, Africa, and North and South 118 America (Viets, 1956:U55-U56)• Koenike (1895:210) record­ ed it from Canada. Wolcott (1902:233) records its occur­ rence in Michigan and Nebraska. Marshall (1935:280) in­ dicates its collection in Alaska, Montana, and Wisconsin in addition to the previous records. Specimens in the writer*s collection have come from three sources in Ohio. On 2 May, 195)+* I collected two specimens in Ashland Co. (Jackson Twnp., R15WT23NS33)• In October, 195it, several specimens collected in a green­ house tank at the Ohio State University by Dr. C. E. Ve- nard were sent to me. On 21 April, 1955, Mr.. Joseph Beatty collected several specimens in Richland Co. (Mif­ flin Twnp., R17WT23NS15). In both natural situations it was found In stand­ ing water. The greenhouse tank represents an artificial situation into which materials had been placed from various natural sources. Therefore it has been impossi­ ble to determine the original source of that material. Individuals in the present collection are slight­ ly smaller than figures given In the literature for this species. Fourteen females In my collection average 0.75^1- mm. in length, ranging from 0.672 mm. to 0.861^ mm. as compared to a maximum size of 1.10 mm. stated in the literature (Marshall, 1935:280). The single male In this 119 collection Is 0.576 ram. in length, compared to a figure of 0.80 ram. given in the literature (Marshall, 1935*280;

Soar and Williamson, 1927:186-187). Wolcott (1902:231) gives figures of 0.9 rani, for females and 0.75 mm. for males. The color of living American material is not stated in the literature. However, Wolcott (1902:233) states that the legs and eplraeral plates of preserved specimens Bhave retained a deep blue tint.” The writer’s material is noted pale bluish-green in color. European material is recorded as yellow with brown patches (Soar and Williamson, 1927:186; Viets, 1936:3^6 ).

Female. The epimera of P. rotunda are arranged in four groups of two each (Pig. II4.2 ) . The gnathosomal plate is broad and closely adjacent to epimera I. The suture between epimera I and II is complete. The suture between epimera III and IV is Incomplete medially. The posterior margin of epimera IV is produced into a taper­ ing, pointed projection. External genitalia of the female consist of a pair of crescent shaped plates flanking the orifice. The spec­ imen illustrated in Figure lij.2 shows 16 acetabula on the plate and four in the integument medial to the plate. Wolcott (1902:233) gives the range for this species at 120 20-26 acetabula on each side. The anterior and posterior tips of the genital plates bear four to six fine setae. The lateral extent of the genital sclerite, which does not reach beyond the posterior projection of epimera IV, Is an aid in distinguishing this species from the next to be considered, P. relghardl. The palpus of P. rotunda females (Pig. 1^3) Is slightly less than half the length of the entire body. P-l is broad and short, with a fine seta on its extensor surface. P-2 Is longer than broad and convex on the flex­ or surface, giving a slightly swollen appearance. The medial surface of P-2 bears two short, stout spines, and distally on the extensor surface is an elongate, fine spine. P-3 bears a single stout spine on its medial sur­ face, and a fine spine distally on the extensor surface. The flexor surface of P-l}. bears rounded papillae with two fine setae. P-5 terminates in three rounded, fingerlike projections, accompanied by two setae, one on the flexor surface, the other on the extensor surface.

Male. Sexual dimorphism is noted in the genitalia, the appendages, and the epimeral sclerites of P. rotunda. The posterior projection of the margin of epimeron IV is less attenuated in males (Fig. li|lp) than in females. 121 The genital plates of males are more tongue-shaped than those of females, and are joined medially in front of and behind the genital orifice- Laterally the genital plates of the male reach just beyond the tip of the posterior projection of epimeron IV. The genital plate of each side contains 16 acetabula. This agrees with the situation indicated by Marshall (193p: Pig- 26) but differs from the figure of "thirty or more" stated by Wolcott

(1902:233)• The palpus of males of P. rotunda (Fig. lij.f>) differs slightly from that of females. Papillae on the flexor surface of P-if are more prominent in males than in females, and a fine seta on its extensor surface has not been seen in females.

Sexual dimorphism of podomeres III-6 and IV-ij. is noted in P. rotunda (Pigs. l!|.6 and Uj-7). Segment III-6 is cylindrical in shape and excavated on the distal end.

Terminally it bears a straight, stout spine and three weaker spines. Two fine setae are located on the flexor surface. A long, stout spine on the distal end of III-!? parallels the extensor surface of XII-6. Podomere IV-lj. shows the medial excavation characteristic of males of the genus. In this species there is a row of six stout pegs proximal to the excavation and four distal to the excavation including one spurlike spins on the distal tip 122 of the podomere. On the flattened surface of the podo-

mere are four stout spines. On the margin opposite the

excavation are two stout spines.

Nymph. The ventral surface of a laboratory hatched nymph of P. rotunda is shown in Figure 1J|8. The epimera show a general similarity to those of females, though differing slightly in outline. A variation is also noted in the fact that the suture between epimera III and IV is complete in the nymph, whereas it is imcomplete medially in adults. The provisional genitalia consist of two pairs of large, prominent acetabula. At the level of the posterior pair there is, in the midline, an excretory pore surround­ ed by a sclerotlzed ring. The nymphal palpus Is similar in proportions to that of the adult, except that nymphal P-Ij. is not as elongate as In adult P-^_.

Eggs. Females from all three sources whence the writer is material came laid eggs in rearing dishes. The clutches ranged in size from two to 23 eggs averaging 12+ eggs. The eggs shown in Figure 1$0 were laid by a female taken from the Ohio State University greenhouse tank. Only one clutch, that laid by a Richland Co. female, hatched, and that clutch hatched only in part. These eggs produced nymphs rather than larvae. This agrees with the observations of Piersig (cited by Soar and Williamson, 1925:2k) that the larval stage of P. rotunda is entirely suppressed. Eggs of P. rotunda observed in the present study are noted as colorless, neutral to tan, and pale-orange to white. In general they have been Individually encap­ sulated, but in some instances there have been two eggs per capsule.

Host. The host of P. rotunda in Ohio is unknown, if indeed It has a parasitic stage. Viets (1939) has e reported P. rotunda from the gill chambers of Astacus leptodactylus. However, this record must remain in some doubt since he records all stages, including the larva, which is at least in some cases suppressed.

Piona reighardl (Wolcott, 1902) This species, originally described by Wolcott from specimens collected in Michigan, Illinois, and Indi­ ana, has been recorded over a wide area of the United States. Records from Alaska (Marshall, 1921).:2l\l) and of the Canadian Arctic Expedition are, according to Marshall (1935t282) probably not correct. It has been recorded 12k from Ontario, Michigan, Montana, Indiana, Illinois, Iowa, Louisiana, Georgia, and Wisconsin (Marshall, 1935*281- 282). Miller*a listing (1925*12)4.) of the species from Buckeye Lake, Ohio, is not included by Marshall, although she apparently made the determination. Hoff (19M+:68) records P. reighardi from Reelfoot Lake, Tenneessee. The writer»s material includes three females, 12 males and one nymph taken In Put-in~Bay and five nymphs and four larvae collected from midges on Gibraltar Island. The determina­ tion of adult material has been by comparison with speci­ mens collected by Marshall in Vilas Co., Wisconsin, which were loaned by the Chicago Natural History Museum. Cor­ relation of nymphs with adults has been made on the basis similarity of morphology. Correlation of larvae and nymphs has been accomplished by rearing the nymphs from larvae collected from midges kept over water.

Female. Females of P. reighardi in my collection are slightly smaller than the figures given in Wolcott* s original description. These specimens average 0.752 mm. in length, compared to an average of 0.9 mm. stated by Wolcott (1902:235). Females of P. reighardi can be distinguished from P. rotunda only with difficulty (Marshall, 1935*280). A 125 few differences In proportions of the epimera and geni­ talia are noted in the Ohio material. The epimera of "P. reighardi are, as in P. rotunda, arranged in four groups of two each (Pig. 151). Epimeron III of P. reighardi is longer and narrower than in P. rotunda. The posterior margin of epimeron IV shows a more rounded posterior pro­ jection than is the case in P. rotunda. The number of ace tabula and the shape and lateral extent of the genital sclerites Is highly variable. In the specimen figured there are 18 and 19 acetabula on the right and left sides respectively. Seven sued four of these are free in the integument rather than on the genital sclerites. The palpi of P. reighardi (Pig. 152) are stouter than those of P. rotunda; p-2 of P. reighardi is broader than that of P. rotunda. The palpi of P. reighardi are slightly more than two-thirds the body length, whereas those of P. rotunda are slightly less than half the body length.

Males. Males of P. reighardi are readily differ­ entiated from P. rotunda in that the genital sclerites ex­ tend laterally well beyond the posterior projection of epimeron IV (Pig. 153)* As in P. rotunda there is varia­ tion in the number of genital acetabula. Wolcott*s de­ scription states wabout 35” per plate (Wolcott, 1902:238). 126 Marshall (1935:281) states ’'twenty to twenty-five on each side." The specimen figured by the writer shows 38 ace­ tabula on each side. The palpus of P. reighardi males (Pig. 1$1|) shows prominent seta-bearing papillae on the flexor surface, as contrasted with the lower papillae of females of the same species and of both sexes of P. rotunda.

Podomeres III-6 and IV-ij. show characteristic modi­

fications as in other male pionas. Segment III-6 is slightly narrower at its base than distally (Pig. 155)• Distally it hears a curved, elongate spine, shorter than that of P. rotunda. Terminally there is also a straight, stout seta and a straight, fine seta. Proximally on the flexor surface is a stout spine. Two spines from segment XII-5 parallel the extensor margin. The marginal indentation of IV-ij- (Pig. 156) shows outstanding differences from that of P. rotunda in the number and arrangement of setae. The proximal edge of the indentation shows three long and four short spines interspersed. The proximal edge bears two short spines. The distal margin of the podomere bears three long spines and one short spine on its flexor border. The surface of the podomere bears three long spinas. Distally, near the flexor edge, Is a short spine. 127

Nymph. Five nymphs which emerged from nympho- chrysalids taken from midges (Tendipedidae) collected on Gibraltar Island In July, 195^4-, have been referred to this species, as has one nymph collected In Put-in-Bay. The midges have been identified as Tendipes (Tendipes) decorus (Johannsen) by Dr. Paul H. Arnaud, Jr., U. S. National Museum. The nymphs of reighardi average

0.^32 mm. in body length, ranging from 0.1^2 mm. to 0.672 mm. The epimera (Fig. 157) show outlines generally simi­ lar to those of the female. The inter-eplmeral suture between epimera III and IV is complete. The provisional genitalia are characterized by the presence of several acetabula. These are arranged sym­ metrically, lying free in the post-epimeral integument. The acetabula number five on each side, the anteriormost being larger than the others and with a sclerotized ring around it. The palpus of the nymph shows a peculiar modifi­ cation of P-I4. (Fig. 158)* Two papillae are present on the flexor surface at the distal ends of longitudinal ridges. The medial one of these is about one-third the length of the segment from its base. The lateral papilla is about two-thirds the length of the segment from its .. 128 base. Each of these papillae bears a short, fine seta. Distally on the flexor surface is a conical, toothlike peg.

Larva. Figure 159 shows the structure of larvae from which developed the nymphs just described. Four of

these larvae averaged O.33I mm. in length, exclusive of the gnathosoma; the larvae are nearly circular in outline. The gnathosomal plate is broad, and pentagonal in outline. Epimera I are separated from epimera II by a complete suture. Epimera II and III are indistinguishably fused and are characterized by a pointed posterior projection. All epimera of this larva are oriented longitudinally. Prominent setae are borne on the posterior end of epi­ mera I, on the surface of epimera II-III, and at the pos­ terior margin and medial margin of the epimeral group. In the midline, at the level of the posterior end of the epimera, is a prominent excretory pore. This pore is surrounded by a sclerotized ring bearing two pairs of fine setae. Five additional pairs of short, fine setae and one pair of long, stout setae flank the excretory pore in the post epimeral integument. 129

Plona naplo, n. sp. Diagnosis. Pionlds with characteristics of the genus Plona. Females with an elongate spine on the flexor surface of P-2. Genital sclerites of males meet­

ing posterior projections of epimera IV. Suture between

epimera III and IV incomplete medially in males.

My collection of Ohio water mites contains over 100 adults and nymphs of Piona which differ in certain re spects from known members of the genus and are herein de­ scribed as new. For this species the name Plona napio Is suggested, the specifio trivial being derived by anagram from the generic name. This species falls into the sub­ genus Piona as distinguished by Viets (1936:332). Piona napio has been collected by the writer In Ashland Co. (Orange Twnp., R16WT2NS11), Licking Go. (Liberty Twnp., Rll|WT3NS7), and the following locations in Wayne Co.: Chippewa Twnp., R11WT18NS21; Green Twnp., R12WT17MS31S Wooster Twnp., R13WT15HS31? Clinton Twnp., Rl^WTl8NS21; Plain Twnp., RlijWT19NS32, and Chester Twnp., RlI|.WT20NS25. Specimens of this species have been trans­ mitted to the writer by Mr. Joseph Beatty, from Franklin Twnp., R13WTlifNS^, and Wooster Twnp., R13WT15NS32. 130 With the exception of a few specimens from Brown’s Lake the material has all been taken from vernal woodland pools. All collections were taken between 18 March and 2 May in the years 1952-1956. The earliest seasonal spec­ imens, 18 March, 1953> were nymphs, whereas later collec­ tions were primarily adults. Adults of P. napio checked against Munsell (1929) color standards are yellowish Red, 7-5 R il/12.

Females. Females of Piona napio are ovoid in out­ line, being broadest slightly behind the middle. Twenty females averaged 1.267 mm. in body length, ranging from 1.056 mm. to 1.632 mm. The epimera are limited to the anterior half of the ventral surface (Fig. 160). Epimera are arranged in four groups of two each. There is an area of non-sclero- tized integument between epimera II and III which is nearly equal in width to epimera II. A prominent glandu­ lar pore is situated behind epimera II. Epimera III and TV are separated by a complete suture. The posterior margin of epimeron IV is produced into a pointed poster­ ior projection. The external genital apparatus is about one-half enclosed in a bay formed by the diverging margins of epi­ mera IV. The slitlike genital orifice Is flanked by a 131 pair of crescent shaped genital sclerites. Each genital sclerite bears eight to ten acetabula. At the anterior and posterior tips of the genital sclerite are clusters of three to five fine setae. The palpus (Fig. 161) is about one-third the length of the body. P-l is short and broad. P-2 is approximate­ ly as wide as it is long, and bears two pairs of stout setae on its extensor surface in most individuals. The flexor surface bears a fine bristle situated about two- thirds the length of the segment from its proximal end, a characteristic which distinguishes females of P. napio from other species of the genus. P-3 is approximately equidimensional and bears a pair of stout setae midwpy, near the extensor surface. Distally on the same surface is a single spine which projects beyond the base of P-l}.. The flexor surface of P-l}. bears a fine seta slightly be­ yond the middle of the segment, and another nearer the distal end of the segment. Opposite the latter, on the extensor surface, is still another seta, this one some­ what stouter. P-L;. is slightly more than three times as long as its width at the middle. The distal podomere, P-5, is swollen at its base. It terminates in three fingerlike processes. Sub-terminally on the flexor sur­ face is a fine seta. 132

Male. Ten males in the collection range from 0.672 mm. to O.96O mm. In body length, averaging 0.81^2 mm. In males the body Is nearly as broad as long, the individuals being nearly circular in outline. Epimera of the male cover the anterior two-thirds of the ventral surface (Pig. 162). They are more closely arranged than in the females. A gland pore is located behind epimera II. Epimera III and IV are separated by a suture which is incomplete medially. The posterior margins of epimera IV show pointed projections which meet the genital sclerites. The genital sclerites of the two sides are joined in the midline by sclerotized bridges in front of and behind the genital orifice. The lateral margins of the genital plates are produced into blunt points. There are ten to 12 acetabula on the plate of each side. The aedeagus is shown in Figure 16. Posterior to the genitalia, lying In the midline is a large excretory pore surrounded by a sclerotized ring. The palpus of P. napio males shows a marked sexual dimorphism (Pig. I6 3 ). It is slightly less than one-half the body length In males. Proportionate length of the 133 podomeres is similar to that of females. P-2 of males lacks the seta on the flexor surface which is present in females. The paired setae of the extensor surface of P-3 are long and stout, extending beyond the base of P-I^.. Papillae on the flexor surface of P-]+, two in number, are elongate and prominent, each bearing a long, fine seta.

As in other male pionas podomeres III-6 and IV-I4. of P. napio are sexually differentiated. Podomere III-6 is strongly curved, and proximally it bears a knoblike spur (Pig. 13). The segment is about two-thirds the length of III-5- Midway on the concave surface is a pair of fine setae. Distally the segment bears a stout, curved spine surrounded at its base by several short, fine setae. Podomere IV-I}, bears the prominent concavity characteristic of Piona males (Pig. 12). The proximal margin of the excavation bears one long seta and several (up to ten) shorter, stouter setae. The distal margin of the excavation bears up to eight short, stout setae. The flattened surface of the podomere bears three long setae. The margin opposite the excavation bears two setae. Dis­ tally podomere IV-lj. of Piona napio bears three long setae, three to five shorter, fine setae, and, on the flexor margin, a short, stout spine. 13^

Nymph. Five nymphs of Fiona napio measure 0.672 mm. to 1 .0£6 mm. in body length, averaging 0.983 mm.

The epimera of the nymph (Fig. I6I4.) are similar in out­ line and arrangement to those of the female. The suture between epimera III and IV Is incomplete medially in the nymph as in the male, whereas it is complete medially In the female. The provisional genitalia of P. napio consist of paired genital sclerites, each with two large acetabula. The genital sclerites are arranged obliquely, the poster­ ior ends diverging. Each plate bears three fine setae. The plates are broadest midway of their length. A small excretory pore lies in the midline between the genital sclerites. The nymphal palpus (Fig. 165) shows greater simi­ larity to that of the male than to that of the female. The long seta near the extensor surface of P-3 and the prominent papillae of the flexor surface of P-l|_ are characteristics similar to those of the male. There Is, however, only a single papilla on P-ij.. A second long, fine seta arises directly from the surface, without papilla. 135

Larva. Twenty laboratory hatched larvae of Plona napio average 0.393 mm. In body length, ranging from 0.317 mm. to 0.1flf.2 mm. These figures represent the body length exclusive of the gnathosoma. The body is oval In out­ line, being broadest just anterior to the middle of the body length (Pig. 166). Epimera I are separated from epimera II by a distinct suture. Epimera II arid III are incompletely separated by a suture which begins laterally and extends slightly more than halfway across the epimer­ on toward the midline. A prominent notch is present mid­ way on the medial margin of epimera II-III. The postero­ medial margins of epimera II-III diverge from the midline forming a shallow bay. The epimera cover nearly all the ventral surface. Epimera I bear setae near their poster­ ior tips. Similar setae are present just back of the medial ends of the suture between epimera II and III. Hie posterior-medial angles of the epimera bear a pair of fine setae. The post-epimeral integument bears four pairs of moderately developed setae, and a single pair of long, stout setae on the posterior margin of the body. An excretory pore Is situated In the inter-epimer­ al bay. This is surrounded by a sclerotized ring and flanked by two pairs of fine setae. 136

Eggs. Fourteen egg masses of Plona napio varied In number from five to 29 eggs, the average number being 15+ eggs per clutch. Clutches were deposited on Myr1o- phyllum or on the walls of the rearing dish. The largest of the clutches is shown in Figure 167. These eggs were laid in a single layer and individually encapsulated. Newly deposited eggs checked against Jfunsell (1929) color standards are yellowish Red, 7-5 R 5/l0. They are circu­ lar in outline and measure approximately 0.12 ram. in diameter.

PQ ve1opmental observations. Three egg clutches ft&Plo which were observed at regular Intervals showed minimum hatching times from four to nine days, averaging 6.6 days from deposition'. In one culture larvae survived up to 26 days without host insects being available for feeding. In three other cultures, 3k$ adult mosquitoes (Aedes aegypti) whdc h emerged in culture with mite larvae were examined. None of the mosquitoes showed mites attached, and none of the mite larvae showed signs of having fed.

Comparisons. Piona napio, n. sp., is distinguished from other species of the genus by characteristics of the female palpus and the male genitalia and legs III and IV. 137 The presence of a spine on the flexor surface of P-2 differentiates the female from all other females of the genus. The absence of papillae on P-l| is unusual in the genus, but is known, e.g. in P. clavicornis (Muller, 1776). However, in P. clavicornis the female genital acetabula are not borne on plates. Both sexes bear resemblance to Piona constricta (Wolcott, 1902), but can be differentiated therefrom. Females of P. constricta do not possess the spine on P-2 as indicated above. Palpi of the female of P. con­ stricta bear prominent papillae on P-1+. Males of P. napio can be differentiated from those of P. constricta by the fact that the suture between epimera III and IV is complete in P. constricta, incomplete in P. napio and spination of podomere IV-lj. differentiates the two species, that of P. constricta bearing many more setae than that of P. napio. The genital sclerites of P. constricta males are In contact with the epimera medially, whereas

those of P. napio are not. Male podomere III-6 Is of similar shape In the two species, but bears more setae in P. constricta. Females of P. napio are much smaller than the figure of 1.720 nan. given by Wolcott for P. constricta females. 1 3 8

Type material. Holotype, allotype, and paratypes will be deposited in the Chicago Natural History Museum. Paratypes will be placed in the Ohio State University Entomology Museum and others retained in the writer*s collection.

XI. FAMILY ARRENURIDAE

The writer*s collection contains ten males of Arrenurus (Arrenurus) latioornls Marshall, 1908 and two males of Arrenurus (Megaluracarus) marshallae (Piersig, 190i{.) taken In Buckeye Lake, Licking Co., on 2I4. August, 1956. in addition there are 12 females and 11 nymphs from the same source, and numerous larvae hatched from these females. There are also eight females and a few larvae from various locations in Wayne Co., and two nymphs from the Ohio State University farm pond in Franklin Co. The separation of Arrenurus species has been based primarily on males, with females being described only as they could be related to males. The females in this collection do not agree well with specimens of and infor­ mation about the two species represented by males, and it has therefore been deemed inadvisable to assign the fe­ males. Futhermore, another species of the genus, A. trifoliatua has been recorded from Buckeye Lake by Miller 139 (1925)* which enhances the possibility of incorrect assignment. For these reasons, only the males will be presented here.

Arrenurus (js. _s. } laticornls, Marshall, 1908 This species has been previously recorded from Illinois (Marshall, 1910:105), from Illinois, Iowa, Missouri, and Wisconsin (Marshall, 19ii0b: 151), from Reelfoot Lake, Tennessee (Hoff, 19ijli-*56), from Michigan (Cook, 195)|-a:5l)* The ten males In the writer1s collection average l.lOlj. mm. In length by 0.816 mm. In width. These dimen­ sions are very constant, only two individuals varying from the average in length and three In width. In dor­ sal aspect this mite presents a rounded forebody and a broad posterior cauda (Fig. 168). As in other members of this subgenus, the cauda is divided into three parts, two corner processes (pygal lobes) and a medial petiole. In A. laticornis the petiole consists of a central piece and a basal piece, the central piece extending beyond the basal piece and being broadly notched at the tip. The petiole is without bristles. It Is surrounded at its base by a broad hyaline appendage. Field notes indicate the color of this species as green. 114-0

Arrenurus (Megaluracarus) marshallae (Piersig, 19Ql\.) This is one of the commonest species of arrenuri having been widely reported in the United States. By

1910 it has been reported from 1$ states and Canada

(Marshall, 1910:102). At that time Marshall reported it from Ohio, where it was collected at Put-In-Bay by the

U. S. Pish Commission in 1899- These specimens have been examined by this writer and one is illustrated in Figure

170. The same paper reports the speoies from Louisiana and Texas. Subsequent reports, indicative of its range,

Include: Sebago Lake, Maine (Marshall, 191J+:1 3 0 3 ); Wis­ consin and Ontario (Marshall, 1 9 i|.0 b :lLf-5-lij.6); Washington

(Lavers, 19b-5• ) • Miller (1925:122) listed the species from Buckeye Lake, Ohio. The subgenus Megaluracarus, of which A . marshallae is representative is characterized in part by a long cauda (short in a few species) and the absence of pygal lobes. A. marshallae is representative of a group with a long cauda and hornlike projections over the eyes

(Pig. 169) . In A. marshallae the posterior end of the cauda is slightly indented, a feature which aids in distinguishing it from a very similar form, A. megalurus, where the indentation is deep. llf.1

The two males in the writer’s Buckeye Lake

material average O.98I4. mm. in length by 0.60 mm. in

width. Field notes indicate their color as green.

XII. UNASSIGNABLE MATERIAL

In addition to the material reported above the writer has the following material not specifically determinable: Eylaidae - 1 Eylais Ny. (Ohio State University farm pond, Franklin Co., 7 Aug., 1956) Limnesiidae - 1 Tyrrellia sp. (Miller’s Blue Hole, Sandusky Co., 13 Jul., 195*4-) Unionicolidae - 19 adults and nymphs, Union!» cola sp. (several locations in Lake Erie, summer and fall, 195*+> Britt and Crowell) Pionidae (?) - 1 nymph (Beach City Reservoir, Tuscarawas Co., 7 Aug., 195*4-) Axonopsidae - 1 Axonopsis sp. (Put-in-Bay, Ottawa Co., 25 June, 195*4-)

XIII. ADDITIONAL RECORDS

The following species of water mites have been reported from Ohio, but have not been identified In the present survey: Limnesiidae - Llmnesla pauclspina, collected by: A. E. Miller, Buckeye Lake, Aug., 1923, (Miller, 1925:123). L. fulgida (=L. hlstrionica) collected by: A. E. Miller, Buckeye Lake, Aug., 1923# (Miller, 1925:123). Tyrrellla circularia, collected by: C. K-m Brain, Cedar Point, Black Channel, 15 Aug., 1912, (Miller, . 1925:12i|J. Unionicolidae - Unionlcola craasipes, collected by: A. E. Miller, Buckeye Lake, Aug., 1923, (Miller, 1925:122). Neumanla diatincta, collected by: A. E. Mil ler, Buckeye Lake, Aug., 1923, (Miller, 1925:123). N. punctata, collected by: A. E. Miller, Buckeye Lake, Aug., 1923, (Miller, 1925:123) Arrenuridae - Arrenurus manubriator, collected by: TJ. S. Pish Commission, Put-in-Bay, July, 1899, (Marshall, 1910:101). A- apetiolata, collected by: IT. S. Fish Commission, Put-in-Bay, 1899, (Marshall, 19.10si01j.) • A* aroericanus, collected by: U. S. Pish. Commission, Put-ln-Bay, 1099, (Marshall, 1910:107). A. trifoliatus, collected by: A. E. Miller, Buckeye Lake, Aug., 1923, (Miller, 1925: 122). iL* reflexus, collection not annotated, (Marshall, 19lj.0b:l50). SUMMARY

1. The collections reported were made in central and north central Ohio during the period 1952 to 1957* Nineteen species are recorded representing 12 genera in 11 families. Four species are new: Hydrachna baoulo- scutata, Hydryphantes waynensis, Torrentloola bltti- koferae, and Plona napio. 2. An annotated list is included, naming 11 species previously reported from Ohio, which have not been recognized among material collected in this survey. 3- Developmental and life history observations have been recorded. Immature stages have been reported when they could be correlated with adult forms. i|-. Host insects are indicated for Hydrachna magni scutata, Thyas stolli, Limnesia undulata. and Piona reighardi. 5- Morphological details of all identified forms are illustrated. 6. Collecting apparatus and techniques used by the writer are described and evaluated. 11*4 LITERATURE CITED

Certain works cited in the text, primarily refer­ ences to eighteenth and nineteenth century publication of scientific names, have not been seen by the writer and are not included in the following list. These, and other papers on the Hydracarina, can be found listed in the comprehensive bibliography of Viets (1955 and 1956)*

Abdel-Malek, A. A. 19l|.8. The biology of Aedes trivit- tatua. Jour. Econ. Ent. 1^1: 95l~95ii* Bader, C. 1938* Beitrag zur Kenntnis der Verdauungs- vorgfinge bei Hydracarinen. Rev. Suisse Zool. ii5: 721-8 0 6 . ______, 19$k' ^as Darmsystem der Hydracarinen. Rev. Suisse Zool. 6l: 505-5U9. Baker, E. ¥. and G. W. Wharton 1952. An Introduction to Acarology. l-ij.65. Macmillan, New York. Butler, J. M. and A. W. Grundmann 1953* Improved micro- dissecting instruments for helminthological and other zoological use. Turtox News jil: 2-3. Chandler, E. R. 193^4-* Unionlcola aculeata (Koenike) in snails In North Carolina. J. Parasitol. 20: 312.

Iii5 11+6 Cook, D. R. 195!|a. Preliminary list of the Arrenuri of Michigan. Part I. The subgenus Arrenurus. Trans. Amer. Micros. Soc. 7^3: 39-58* ______195^1-b. Preliminary list of the Arrenuri of Michigan. Part II. The subgenus Megaluracarus. Trans. Amer. Micros. Soc. ]Q: 367-330. 195$. Preliminary list of the Arrenuri of Michigan. Part III. The subgenera Micruracarus and Truncaturua. Trans. Amer. Micros. Soc. Tlj.: 60-67. ______and R. D. Mitchell. 1952 Notes on collecting water-mites. Turtox News JJ0+ 122-125. Crowell, R. M. 1950. Preliminary observations on the occurrence of water-mites on insects In the Duke Forest. J. Parasitol. J6(6, sect. 2): 32. 1953* Morphology and developmental stages of Plona linguaplax, n. sp. (Hydracarina: Plonldae) a water-mite from North Carolina. Amer. Mid. Nat. £0 : I5.26-I4.3 2 . ______195b' A ''Dipping-horn" for the collection of water-mites and other minute, swimming arthropods. Turtox News 32: IH4.-H5 . Elias, H. 1950. Discovery by illustration. Scientific Monthly 70: 229-232. li-j-7 Prison, T. H. 1929. Pall and winter stone-flies, or Plecoptera, of Illinois. 111. Nat. Hist. Sur. Bui. 18, Art. 2: 3^-0-)f,09. Habeeb, H. 195b' North American Hydrachnellae, Acari. IX-XVI. Leaflets of Acadian Biology, Grand Palls, New Brunswick, No. 2: I-II4.. ______1955- North American Hydrachnellae, Acari. XXVIII. The fusion formula. Naturalists Canadian. 82: 186-188. Hoff, C. C. 19kb' A preliminary study of the Hydracarina

of Reelf00t Lake, Tennessee. Jour. Tenn. Acad. Sci.

19: 1+5-69. Imamura, Taiji 1950. On the life-history of Fartunia uchidaei, a water-raite parasitic on stone-flies. Annot. Zool. Japonenses. 21^.: 51+-58. ______1951* Studies on three water-mites from Hokkai- do, parastic on midges. Jour. Pac. Sci., Hokkaido Univ., Ser. VI, Zool. 10: 27l|--288. ______1952a. (Studies on a water-mite, Limnochares aquatica, parasitic on pond-skaters.) Zool. Maga­ zine 6 1 : 227-232. ______1952b. Notes on the moulting of the adult of the water mite, Arrenurus uchidae, n. sp. Annot. Zool. Japonenses. 2.5' 1+1+7—i+5l- 048 Koenike, P. 1895- Nordamericanische Hydrachniden. Abh. naturw. Ver. Bremen, 1^: 167-226. ______1896. Zwei naue Hydrachniden-Gattungen nebst sechs unbekannten-Arten. Zool. Anz. 19: 356-362. ______1908. Baitrag zur Kenntnls der Hydrachniden. Abh. nafcurw. Ver. Bremen. _19: 217-266. ______1912. A revision of my "Nordamericanische Hydrachniden." Trans. Can. Insfc., Toronto. 9: 281-296. Lavers, C. H. 1945* The species of Arrenurus of the state of Washington. Trans. Amer. Miseros. Soc.

6Jjl: 228-26^. Lundblad, 0. 1934* Die nordamerikanische Arten der Gattung Hydrachna. Ark. Zool. 28A: 1-44* ______1938. Neue Wassermilben aus Paraguay. Zool. Anz. 122: 7-19. ______194l» Eine tJbersicht des Hydrachnellensysterns und der bis jetzt bekannten verbreitung Gattungen dieser Gruppe. Zool. Bidrag Uppsala. 20: 359-379.

______1947* Zur Kenntni3 australischer Wassermilben. Arkiv. Zool. 40A: 1-82. Marshall, J. and J. Staley 1929. A newly observed re­ action of certain species of mosquitoes to the bites of larval hydrachnids. Parasitology 21? 158-160. ll|.9 Marshall, Ruth 1903. Ten species of Arrenuri belonging to the subgenus Megalurus Thon. Trans. Wis. Acad. Sci., Arts and Letters, li^s 114.5-172. _ 1908. The Arrhenuri of the United States. Trans. Amer. Micros. Soc. 28: 85-11+0. _ 1910. New studies of the Arrhenuri. Trans. Amer. Micros. Soc. 29: 97-110. 1911+. Some new American water mites. Trans. Wis. Acad. Sci., Arts and Letters. J-7: 1300-1301^. 1924. Water mites of Alaska and the Canadian Northwest. Trans. Amer. Micros. Soc. IQ: 236-255* 1926. Water mites of the Qkoboji region. Univ. Iowa Stud. Nat. Hist. 11: 28-35. 1927* Hydracarina of the Douglas Lake region. Trans. Amer. Micros. Soc. ij^: 268-285* ______1929a. The water mites of Lake Wawasee. Proc.

Indiana Acad. Sci. 38.1 315-320. ______1929b. The morphology and developmental stages of a new species of Piona. Trans. Wis. Acad. Sci., Arts and Letters. 2l±: i4.Ol-l4.Ol4., ______1929c. Canadian Hydracarina. Univ. Toronto Studies in Biol. No. 33 (Ont. Pish. Res. Lab. Publ. No. 39). 57-93* 150 1930. Water mites of the Jordan Lake region. Trans. Wis. Acad. Sci., Arts and Letters. 25: 2145-253. 1932. Preliminary list of the Hydracarina of Wisconsin. Part II. Trans. Wis. Acad. Sci., Arts and Letters. 27: 339-357. 1933* Water mites from Wyoming as fish food.

Trans. Amer. Micros. Soc. 52: 3I4-I4JL. 1935* Preliminary list of the Hydracarina of Wisconsin. Part IV. Trans. Wis. Acad. Sci., Arts and Letters. 29: 273-297. 1936. Hydracarina from Yucatan. Carnegie Inst.

Wash. Publ. No. I4.5 7 : 133-137. 1937* Preliminary list of the Hydracarina of Wisconsin. Part V. Trans. Wis. Acad. Sci., Arts and Letters. JO: 225-251. 19l|.0a. On the occurrence of water mites In the food of turtles. Amer. Mid. Nat. 2k: 3 6 I-36I4.. 19l4.0b. Preliminary list of the Hydracarina of Wisconsin. Part VI. Trans. Wis. Acad. Sci., Arts and Letters. J2: 135-165* 19i4.3a. Hydracarina from California. Part I. Trans. Amer. Micros. Soc. 62: 3O6 -32I4.

19l4-3h. Hydracarina from California. Part II.

Trans. Amer. Micros. Soc. 62: I4.OI4.-I4I5 . 151 ______191+6. Preliminary list of the Hydracarina of Wisconsin. Revision of Part I. Trans. Wis. Acad.

Sci., Arts and Letters. ^6 : 31+9-373* McClure, H. E. 191+3' Aspectlon in the biotic communi­ ties of the Churchill area, Manitoba. Ecol. Monog.

12 * Miller, A. E. 1925* An introductory study of the Aca- rina, or mites, of Ohio. Bull. Ohio Agri. Exper.

Sta. No. 3 8 6 : 83-172. Mitchell, R. D. 1951+' Check list of North American water-mites. Fieldiana jjj?: 29-70. ______and D. R. Cook. 1952. The preservation and mounting of water-mites. Turtox News ^0: 169-172. ______and W. G-. Pitchford 1953* On mites parasitizing

Anodonta in England. Journ. Conchology. 23.: 365-370. Munsell, A. E. 0. 1929. Munsell book of color. 2 vols. Munsell Color Co., Inc, Baltimore, Md. Newell, I. M. 191+7. A systematic and ecological study of the Halacaridae of eastern North America. Bull.

Bingham Oceanographic Coll. 10: 1-232. Pennak, R. W. 1953* Fresh-water Invertebrates of the United States. 1^769. Ronald Press, New York. Piersig, G-. R. 1897* Einige neue deutsche Hydrachniden. Zool. Anz. 20: 51+1. 152 __ 1901. Acarina, Hydrachnidae. In Piersig and Lohmann, Das Tierrelch. 13t 1-336. Shelford, V. E. and M. W. Boesel 191+2. Bottom animal communities of the island area of western Lake Erie in the summer of 1937. Ohio Jour. Sci. 1+2t 179-190. Soar, C. D. and W. Williamson 1925• The British Hydrac­ arina. Vol. I. The Ray Society. London. Publ. 110: 1-216. ______1927. The British Hydracarina. Vol. II. The Ray Society. London. Publ. 112: 1-215* ______1929. The British Hydracarina. Vol. III. The

Ray Society. London. Publ. 115: I-I8I4.. Thon, K. 1899. Ein neues Hydrachnldengenus aus Bflhmen, nebst einingen Bemerkungen fiber bflhmische Hydry- phantes - Formen. Zool. Anz. 22: 100-102. TJchida, T. and I. Miyazaki 1935* Life-history of a water-mite parasitic on Anopheles. Proc. Imper. Acad. (Japan) IT: 73-76. VIets, Karl 1936. In Dahl, Die Tierwelt Deutschlands. Wassermilben oder Hydracarina. Teil 31-32: 1-571+. J ena. ______1939. Plona rotunda (Kramer) in der KlemenhUle von Krebsen. Arch. Hydrobiol. Ichthyol., Suwalki. 12: 115-116. 1955* Die Milben des Sflsswassers und des Meere Teil 1. Bibliographle. l-b76. Jena. _____ 195^. Die Milben des Sfisswassers und des Meere Teil 2/3. Katalog und Norfienklator. 1-870. Jena.

______and Hans-Peter Plate 195k- Die 8kologischen (parasitologischen) Beziehungen zwischen Wassermil­ ben (Hydrachnellae, Acari) und Stlsswasser-Mollusken Zschr. angew. Entomol., Berlin. js£: lj.99-ij.9ll. Viets, Kurt 0. 19lj9. Beitrag zur Kenntnis von Eylals extendens (0. F. Mttller 1776) (Hydrachnellae, Acari) Veroff. Mus. Bremen. Ser. A, Heft 1: ij.1-109. Vitzthum, H. L. W. 19ij.0. Acarina. In H. G. Bronn's Klasaen und Ordnungen dea Tlerreichs. Arachnoidea und kleinere, ihnen nahegestellte Gruppen. 1- 1011. Leipzig. Ward, H. B. and G. C. Whipple 1918. Fresh-water Biol­ ogy. 1-111. Wiley, New York. Wharton, G. W. 195k- Observations on the feeding of prostigmatid larvae (Acarina: Trombidiforraes) on arthropods. Jour. Wash. Acad. Sci. Ijlj.: 2kk~^k5- Wolcott, R. H. 1901. Description of a new genus of North American water mites, with observations on the classification of the group. Trans. Amer. Micros. Soc. 22: 109-117. 1902. The north American species of Curvlpe Trans. Amer. Micros. Soc. 23: 201-266. 1906. A review of the genera of the water- mites. Trans. Amer. Micros. Soc. 26: l6l-2l|3* ILLUSTRATIONS

Explanation of Figures 1-17*

{All scale lines equal 0.25 mm.)

Figure 1. Dorsal shield of Hydrachna magniacutata. 2. Dorsum of Hydrachna baculoscutata Ny. 3. Dorsal shield of Hydryphantes ruber, ij.. Ocular plate of Eylala extendens. 5. Stigmata and chelieeral bases of Piona naplo. 6. Rt. chelicera of Limnesia undulata (medial view).

7 . Chelicera of Hydrachna magniscutata. 8. Rostrum of Hydrachna magniscutata (ventral view). 9. Left palpus of Limnesia undulata (lateral view). 10. Terminal segments of left palpus of Hydrodroma desplciens. 11. Left leg IV of Hygrobates longipalpis. 12. Leg IV-I). of Piona napio, male.

1 3 . Leg III-6 of Piona naplo, male. Ilf.. L e g IV-lj.-6 of Forelia sp. 15- Genital field of Hygrobates longipalpis, female.

155 156 16. Aedeagus of Piona naplo.

17. Venter of Thvas ii i stolli im 11 ——— marked to show arbitrary body divisions according to the scheme of Baker and Wharton (1952) after Vitzthum (191+0). 157

GNATHQSOMA - PROTEROSOMA

PROSOMA

PROPODOSOMA < O2 ______C/i o Q.o metapodosoma-

tO 10 S OMA

— HYSTEROSOMA OPISTHOSOMA . 1.38

Explanation of Figures 18-23. Figure 18. Map of Ohio indicating counties visited in the course of this study. Mites were collected in counties with diagonal lines; collections in those with horizontal lines yielded no mites. (Reproduced by permission of Rand McNally and Company.) 19. Birge net equipment dissembled. Left to right: carrier, silk collection bag, flanged copper tubing, vial of identification numbers, net, protective sleeve, and cone with tow-line attached. 2 0 . Birge net in use in typical open-water habitat. 2 1 . Dipping-horn, for use in collecting surface- swimming mites in shallow ponds. 2 2 . Scrubbing technique, used in collecting mites of rubble beaches. 23. Specimen of Ranatra sp. heavily parasitized Hj&Pachna magniscutata. (Photo by Dr. N. W. Britt.) 159

RgurCS IS* 23 160 Explanation of Figures 21+-38. Figure 21+. Hydrachna magniscutata, female, dorsal shield.

25. H. magniscutata, female, epimera and genital area. Scale as in Fig. 2i+. 26. H. magniscutata, female, right palp, medial view. Scale as in Fig. 21+. 27. H. magniscutata, male, dorsal shield. Scale as in Fig. 21+. 28. H. magniscutata, male, epimera and genital area. Scale as in Fig. 2l+. 29. H. magniscutata, male, left palp, medial view. Scale as in Fig. 21+. 30. H. magniscutata, female nymph, dorsal shield. Scale as in Fig. 2l+. 31. H. magniscutata, female nymph, epimera and genital area. Scale as in Fig. 21+. 32. H. magniscutata, female nymph, left palp, lateral view. Scale as in Fig. 21+.

33- H. magniscutata, male nymph, dorsal shield. Scale as in Fig. 21+. 31+• H. magniscutata, male nymph, epimera and genital area. Scale as in Fig. 21+. 35. H. magniscutata, male nymph, left palp, lateral view. Scale as in Fig. 21+. 161 Figure 36. H. magniscutata, larva, ventral surface. Scale as in Fig. 2i+. 37. H. magniscutata, nymphochrysalid with develop­ ing nymph. Scale as in Fig. 21*..

38. H. magniscutata, eggs. Scale as in Fig. 214.. 162

Figures ZM-38 163 Explanation of Figures 39-E>6 Figure 39. Hydrachna rotunda, male, ventral surface. lj.0. H. rotunda, nymph, epimera III-IV and genital area. ipL. H. rotunda, nymph, right palp, lateral view. Scale as in Fig. J+0

I4.2. H. haculoscutata, female, dorsal plates. Scale as in Fig. 39. lj-3. H. haculoscutata, female, epimera. Scale

as in Fig. 39. J44. H. haculoscutata, female, genitalia. Scale . as in Fig. 39. k-5* H. haculoscutata, female, left palp, lateral view. Scale as in Fig. JpO.

14.6 . H. haculoscutata, male, dorsal plates. Scale as in Fig. 39.

14.7. H. haculoscutata, male, epimera and genital area. Scale as in Fig. 39. 14.8 . H. haculoscutata, male, left palp, lateral

view. Scale as in Fig. I4.O.

14.9 . H. haculoscutata, male nymph, dorsal plates. Scale as in Fig. 39- 50. H. haculoscutata, male nymph attached to Myrlophyllum. l6i| Figure 51. H. baculoacutata, male nymph, epimera and

genital area. Scale as in Fig. 39. 52. H. baculoacutata, male nymph, left palp, lateral view. Scale as in Fig. lj-0. 53. H. haculoscutata, female nymph, dorsal plates.

Scale as in Fig. 39* 5lj.. H. baculoacutata, female nymph, epimera and genital area. Scale as in Fig. 39.

55* H. baculoscutata, female nymph, left palp,

lateral view. Scale as in Fig. ijX).

56. H. baculoacutata, nymph, attached to Myrio-

phylluai. Seale as in Fig. 39. 165

39

48

47

40

0 25 mm 42

46 50

45

44

43

55

53 56

s X, 166 Explanation of Figures 57-89. Figure $7. Eylais extenders, ocular plate. Specimen from Brown’s Lake, Wayne Co. 58. E. extenders, ocular plate. Specimen from Rllj.WT20NS25, Wayne Co. Scale as in Fig. 57 59. E. extenders, ocular plate. Specimen from R12WT17NS11, Wayne Co. Scale as in Fig. 57 60. E. extenders, ocular plate. Specimen from R13WTli^NS5» Wayne Co. Scale as in Fig. 57. 61. E. extendens, ocular plate. Specimen from Ashland Co. Scale as in Fig. 57. 62. E. extendens, ocular plate. Specimen from R15WT2N, Licking Co. Scale as in Fig. 57- 6 3 . E. extendens, ocular plate. Specimen from Rll|.WT3NS7* Licking Co. Scale as in Fig. 57 6ij.. E. extendens, ocular plate. Specimen from

RU 4.WT3NS7 , Licking Co. Scale as in Fig. 57

6 5 . E. extendens, ocular plate. Specimen from N. Bass Island. Scale as in Fig. 57. 66. E. extendens, nymph, ocular plate. Specimen from Rlij.WT3NS7% Licking Co. Scale as in Fig. 57. 167 Figure

67- E. extendens, ocular plate. Specimen from

Grand Rapids, Michigan. Scale as in Fig. 57- 68. E. extendens, female, epimera and genital area.

69. E. extendens, female, gnathosoma, ventral view. Scale as in Fig. 68. 70. E, extendens, female, left palp, medial view. Scale as in Fig. 57. 71. E. extendens, male, external genitalia. Scale as in Fig. 57* 72. E. extendens, papilliform glands. Scale as in Fig. 57. 73* E. extendens, nymph, epimera and excretory pore. Scale as in Fig. 68. Ik- E. extendens, nymph, left palp, medial view. Scale as in Fig. 57- 75* E. extendens, larva, ventral surface. Scale as in Fig. 57. 76. E. extendens, eggs. Scale as in Fig, 88. 77* Thyas stolli, male, dorsum. Scale as in Fig. 68. 78. T. stolli, epimera and genital area. Scale as in Fig. 68. 79. T. stolli, male, right palp, lateral view. Scale as in Fig. 57. 169 Figure

80. T. stolli, male, left palp, lateral view. Scale as in Fig. 57. 81. T. stolli, female, external genitalia. Scale as in Fig. 57. 82. T. stolli, male, external genitalia. Scale as in Fig. 57.

83 . T. stolli, male, aedeagus. Scale as in Fig. 57* T. stolli, nymph, dorsum. Scale as in Fig. 57. 85. T. stolli, nymph, ventral surface. Scale as in Fig. 57.

86. T. stolli, nymph, left palp, lateral view. Scale as in Fig. 57.

8 7 . T. stolli, larva, ventral surface. Scale as in Fig. 57. 88. T. stolli, eggs of Ashland Co. specimen. 89. T. stolli, eggs of Wayne Co. specimen. Scale as in Fig. 88. 169 m mw mw go il tr» S 170 Explanation of Figures 90-105- Figure

90. Hydryphantes ruber, male, dorsal shield.

91- H. ruber, male, right palp, lateral view.

Scale as in Fig. 90.

92* E. ruber, female, external genitalia. Scale

as in Fig. 90. 93* E. ruber, male, external genitalia. Scale as

in Fig. 90.

9^- E* ruber, nymph, dorsal shield. Scale as in Fig. 90.

95- H. ruber, nymph, genital area. Scale as in Fig. 90.

96. H. ruber, larva, ventral surface. Scale as

in Fig. 90.

97* B. ruber, eggs.

98. Hydryphantes waynensis, male,, dorsal shield. Scale as in Fig. 90.

99- E. waynensis, female, left palp, medial view. Scale as in Fig. 90.

100. H. waynensis, female, external genitalia.

Scale as in Fig. 90. 101. waynensis, male, external genitalia.

Scale as in Fig. 90. Figure

102. H. waynensis, nymph, dorsal shield. Scale

as in Fig. 90.

103. H. waynensis, nymph, genital area. Scale

as in Fig. 90.

10l|. H. waynensis, larva, ventral surface. Scale

as in Fig. 90.

105. H. waynensis, eggs. Scale as in Fig. 97. soi-oG ojdQlo O Q O Q o f D o Y O Y O QIQVO /

0.25 mm. 172 173

Explanation of Figures 106-125. Figure

106. Hydrodroma desplciens, female, epimera and genital area. 107. H. desplciens, female, right palp, lateral view. 108. H. despiciena, female, external genitalia. Seale as in Fig. 107. 109. 3* desplclerts, male, external genitalia. Scale as.in Fig. 107. 110. H. desplciens. male, aedeagus. Scale as in Fig.107. 111. H. desplciens, male, anterior dorsal surface. Scale as in Fig. 107. 112. H. desplciens, nymph, epimera and genital area. Scale as in Fig. 107. 113. H. desplciens, nymph, left palp, lateral view. Scale as in Fig. 107. 111].. 3* desplciens, larva, ventral surface. Scale as in Fig. 107. 115- H. desplciens, eggs. 116. Lebertla porosa, female, epimera and genital area. Scale as in Fig. 106. 17U Figure 117- L. porosa, female, left palp, medial view. Scale as in Fig. 107. 118. L. porosa, nymph, epimera and genital area. Scale as in Fig. 107. 119. L. porosa, nymph, left palp, medial view. Scale as in Fig. 107. 120. Torrenticola indlstincta, female, dorsal surface. Scale as in Fig. 107. 121. T. indistincta, female, ventral surface. Scale as in Fig. 107. 122. T. indlstincta, female, left palp, medial view. Scale as in Fig. 107. 123. T. bittikoferae, dorsal surface. Scale as in Fig. 107. 12i|. T. bittikof erae, ventral surface. Scale as in Fig. 107.

125* T- bittikoferae, right palp, medial view. Scale as in Fig. 107. 175

S's-* J \ HS If

OZSfflM

OZ&mm

0*5«» 176 Explanation of Figures 126-lJ^l.

Figure

126. Llmnesia undulata, male,epimera.

127. L. undulata, male, external genitalia. 128. L. undulata, female, external genitalia.

Scale as in Fig. 127- 129. L. undulata, nymph, epimera and genital area. Scale as in Fig. 127. 130. L. undulata, nymph, right palp, medial view. Scale as in Fig. 127. 131. L. undulata, eggs. 132. Hygrobatea longlpalpis, male, epimera. Scale as in Fig. 127. 133. H. longipalpls, male, external genitalia. Scale as in Fig. 127.

134. H. longlpalpis. female, right palp, medial view. Scale as in Fig. 127. 135. H. longipalpls, nymph, ventral surface. Scale as in Fig. 127. 136. H. longlpalpis,nymph, right palp, medial view. Scale as in Fig. 127. 137. Tiphys torris var. americanus, female, epimera, genital area, and anterior margin. Scale as in Fig. 126. 177 Figure

138. T. torrls var. amerlcanus, male, genital area

and posterior margin. Scale as in Fig. 127.

139. T. torris var. amerlcanua, male, right leg IV,

ventral surface. Scale as in Fig. 126.

li^O. T. torrls var. amerlcanua, female, left palp,

medial view. Scale as in Fig. 127.

11^1. T. torris var. americanus, male, left palp,

lateral view. Scale as in Fig. 127. 178

0,25 mm.

0.50mm 179

Explanation of Figures 142-159 • Figure lk2. Piona rotunda, female, ventral surface, li|3- P. rotunda, female, right palp, medial view. 144* P. rotunda, male, epimera and genital area. Scale as in Pig. 142.

II4.5 . P. rotunda, male, right palp, medial view. Scale as in Fig. Iip3. li|6. P. rotunda, male,left leg III-6. Scale as in Pig. llj.3 . 147. P_. rotunda, male, left leg IV-4* Scale as in Pig. Iil3. lij-8* P. rotunda, nymph, ventral surface. Scale as in Pig. lij-3. 149. P. rotunda, nymph, left palp, medial view. Scale as in Pig. 143* 1^0. P. rotunda, eggs, 151. P* reighardi, female, ventral surface. Scale as in Pig. 142. 152. P. reighardi, female, right palp, lateral view. Scale as in Fig. 143. 153- P. reighardi, male, ventral surface. Scale as in Pig. 142. 180 Figure

l$i|„ P. reighardi, male, left palp, medial view. Scale as in Fig. li|3* 199. P . reighardi, male, left leg III-6. Scale as in Fig. lij.3. 156. P. reighardi, male, left leg IV-lj.. Scale as in Fig. ll|3. 1^7* P* reighardi, nymph, ventral surface. Scale as in Fig. li;3. 158. P. reighardi, nymph, left palp, medial view. Scale as in Fig. li+3* 1^9. P. reighardi, larva, ventral surface. Scale as in Fig. li+3* 181

Flares 182

Explanation of Figures 160-170. Figure 1^0. Plona napio, female, ventral surface. 161. P. naplo, female, left palp, lateral view. 162. P. napio, male, ventral surface. Scale as in Fig. 160.

163. P. naplo, male, left palp,medial view. Scale as in Fig. 161.

I6i4_. P. napio, nymph, epimera and genital area. Scale as in Fig. 161. 165. P. napio, nymph, left palp, lateral view. Scale as in Flg.l6l. 166. P. naplo, larva, ventral surface. Scale as in Fig. 161.

167. P. napio, eggs. 168. Arrenurus laticornis, male, dorsal surface. Scale as in Fig. 160. 169. A. marshallae, male, dorsal surface. Scale as in Fig. 160. 170. A. marshallae, male, left lateral view. 183

0.28 mm.

162

160

0.25 mm.

166

164

& 0,53 mm.

169 166

170 0.50mm.

Figures \(*o-no EPILOGUE

In the following bit of fanciful prose Dr. C. B. Philip suggests the water mites of hot springs as possi­ ble last survivors in a world being consumed by fire of the approaching sun. The present writer believes in the importance of all scientific problems and he has found this study of Ohio water mites fascinating, but he also sees the somewhat lesser urgency of scientific informa­ tion on the day to which Dr. Philip refers. ... in the futilely protective shadow of a pro­ truding bit of agatized rib of a long-since extinct whale, itself the last remnant of a once domineering type of animals called verte­ brates that barely survived the catastrophic developments of the so-called atomic age when the world was young and lovely for living things, ... in this shimmering shadow in a now bleak and almost lifeless world steaming in the writhing heat of a merciless, expanding ball of fire in the heavens, and beside the ever boiling caul- drom springs of the North Pole, crouches an anxious, solitary water-mite, the sole survivor of animal life upon this agonized, liquidating planet. There will be no chronicle of her life cycle, and the validity of her scientific name will be a matter of great unimportance. Quoted by permission from Philip, C. B. "Tick Talk," Scientific Monthly. 76: 77-61}.. Febru­ ary, 19^3.

181}. AUTOBIOGRAPHY

I, Robert Merrill Crowell, was born in Sandusky, Ohio, on 29 May, 1921. My elementary and secondary educa­ tion was received in the public schools of that city. In 191{-1 I entered Bowling Green State University, from which I received the Bachelor of Arts degree In 19^5 and the Master of Arts degree In I9l7. Prom 19l|5 to 191+7 I served as teaching assistant to Dr. E. E. Dickerman. During the academic year 1914-7-14-8 I was Instructor of Biology in Kent State University. In 19ij-8 I began further graduate study at Duke University, where my Interest in the Acarina began through an association with Dr. George W. Wharton. From 1951 to 195!? I was a member of the biology faculty of the College of Wooster. During the summers of 1952, 1953, 1955 I was a research assistant in the Entomology Depart­ ment of the Ohio Agricultural Experiment Station.. In the summer of 195U- I entered the Graduate School of The Ohio State University and attended courses in the Stone Insti­ tute of Hydrobiology on Gibraltar Island. From September, 1955, to September, 1958, I was in residence in the De­ partment of Zoology and Entomology, where I was assistant to Dr. Carl E. Venard during the summer of 1958. Since September, 1958, I have been a member of the biology x'acul- ty at St. Lawrence University In Canton, New York.