Miocene Arthropods from the Mojave Desert California By ALLISON R. PALMER With sections by J. C. M. CARVALHO, D. R. COOK, KELLIE O'NEILL, ALEXANDER PETRUNKEVITCH, and R. I. SAILER CONTRIBUTIONS TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 294-G Seventeen species of aquatic and terrestrial arthropods from lacustrine beds of the Ear stow formation are described and illustrated UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price $1 (paper cover) CONTENTS Page Page Abstract—_______________________________________ 237 Systematic paleontology — Continued Introduction _______________________________________ 237 Class Insecta__ _ ________________________________ 249 Methods and procedures-------.------.---------- 238 Order Odonata. _______ ____ _________ _ __ 249 Acknowledgements. __--___-_-___-_____--________ 239 Geology-__________________________________ 239 Order Thysanoptera, by Kellie O'Neill___ _ ___ 251 Characteristics of the nodules_______________________ 240 Order Hemiptera _ _________________________ 255 Preservation of the fossils-_-__-_-____________________ 241 Heteroptera, by R. I. Sailer and J. C. M. Age of the fauna_--__-__-__--____-_______-________ 242 Composition and ecology of the fauna _________________ 2 42 Carvalho _ _ _________________________ 255 Zoogeographic relations_________________-___-________ 243 Homoptera__ _ ________________________ 258 Observations of evolutionary significance.____________ 244 Order Coleoptera___-______--_-_----___--__- 259 Systematic paleontology__-___-_--_________--___----_ 245 Class Crustacea.-_____________________________ 245 Order Diptera_-__ _ _____________ _ _______ 265 Order Anostraca.___________________________ 245 Collecting localities _ _______________________________ 275 Class Arachnida________-_______________________ 246 Literature cited-__--__---_-------__-------___------- 276 Order Aranei, by Alexander Petrunkevitch_____ 246 Order Acarina, by D. R. Cook______________ 248 279 ILLUSTRATIONS [Plates 30-34 follow index] PLATE 30. External views and cross sections of fossil-bearing Page nodules. FIGURE 92. Deltocephalini_________________________ 258 31. Anatomy of Orthemis? sp. 93. Schistomerus californense Palmer, n. gen., 32. Anostraca, Arachnida, Odonata. n. sp., external morphology. ____________ 260 33. Hemiptera, Coleoptera. 94. Schistomerus californense Palmer, n. gen., 34. Diptera. n. sp., tracheal system__-_______________ 263 Page 95. Coleoptera______________________ 266 FIGUEE 83. Index map_-_--_--_---_---_---_--------- 237 96. Dasyhelea australis antiqua Palmer, n. subsp., 84. Key to collecting areas.___-_--__---__--__ 240 adult characters_-____-_____---_---____ 267 85. Detail of principal collecting area___-_---_- 241 97. Dasyhelea australis antiqua Palmer, n. subsp., 86. Anostraca_-_-_-----------__---__---_--_- 245 tracheae- ______________________________ 267 87. Argenna fossilis Petrunkevitch, n. sp_ ______ 246 88. Hydracarina---.-_____-____--__-----__ 249 98. Dasyhelea australis antiqua Palmer, n. subsp., 89. Orthemis? sp__.___________________ 249 larva and pupa characters______________ 269 90. Thysanoptera_--__--_--__-_-____-------- 251 99. Dasyhelea stenoceras Palmer, n. sp__________ 272 91. Miogonates subimpunctatus Sailer and Car­ 100. Culicoides megacanthus Palmer, n. sp _______ 273 valho, n. gen., n. sp____--_____---__--_- 257 101. Calopsectra sp-_-----------__----------- 275 in SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY MIOCENE ARTHROPODS FROM THE MOJAVE DESERT, CALIFORNIA By ALLISON R. PALMER ABSTRACT from calcareous nodules of middle(?) Miocene age that Seventeen species of aquatic and terrestrial arthropods in some features surpass in quality fossils from the representing Anostraca, Aranei, Acarina, and five orders of insects are described and illustrated from lacustrine beds of the world-famous amber deposits. These specimens, which lower part of the Barstow formation of middle (?) Miocene age have been isolated in insoluble residues prepared with in the southern Calico Mountains, Mojave Desert, southeastern dilute formic acid, are abundant at three levels within California. External details of many specimens are perfectly the lower part of the Barstow formation in the Calico preserved. Internal anatomical features are preserved in larval Mountains near Yermo, Calif, (fig. 83). They are water beetles and dragonflies, and adult midges. The arthropods are replaced by at least six minerals, most commonly a crypto- superior to the insects in amber because they can be crystalline variety of quartz. Most specimens have been ob­ freed from the enclosing matrix without loss of detail. tained from formic acid residues of calcareous nodules that are The first fossiliferous nodule to come to the writer's abundant at three or more levels within the upper part of the lower member of the Barstow formation. attention from the Barstow formation in the Calico New species and genera include Argenna fossilis Petrunkevitch, Mountains was discovered by Alien M. Bassett, of the n. sp. (Aranei); Protoarrenurus convergens Cook, n. gen., n. sp. U. S. Geological Survey in January 1954. It contained (Hydracarina); Anaphothrips (Proscirtothrips) vitreus O'Neill, a dragonfly larva which, at the time of discovery had n. sp. (Thysanoptera); Procymophes lithax Sailer and Carvalho, n. gen., n. sp., Miogonates subimpunctatus Sailer and Carvalho, only the ventral parts of three abdominal segments n. gen., n. sp., and Miomonalonion conoidifrons Sailer and exposed. Although the exposed parts were unidentifi­ Carvalho, n. gen., n. sp. (Hemiptera: Heteroptera); Schistomerus able, this was then the first fossil from the lower part californense Palmer, n. gen., n. sp. (Coleoptera); and Dasyhelea ste;rioceras Palmer, n. sp., and Culicoides megacanthus Palmer, n. of the Barstow formation, and it was sent to the U. S. sp. (Diptera). Geological Survey for identification along with another, All larvae of the dytiscid beetle described as Schistomerus seemingly unfossiliferous, nodule. The writer received californense Palmer have characteristics found only in first stage larvae of the most closely related modern species. They are designated as representatives of a new tribe, Schistomerini Palmer. A modern species, Dasyhelea australis Wirth (Diptera), from the Islas Juan Fernandez west of central Chile, is represented in the fossil fauna by a subspecies, D. australis antiqua Palmer, n. subsp. The aquatic fauna seems to be most like that of an alkaline pond. It is composed almost entirely of immature individuals and dominated by Schistomerus californense Palmer, Dasyhelea australis antiqua Palmer, and a fairy shrimp. The presence of specimens with excellently preserved internal anatomical features suggests a nearly aseptic chemical environment in the bottom sediments. INTRODUCTION Well-preserved fossil nonmarine arthropods are known from only a few deposits in the world. The best known of these are deposits of amber which have also yielded by far the greatest numbers of fossils. This -—Index map of southern California showing general position, of area paper is concerned with fossil nonmarine arthropods from which fossil arthropods were collected. 237 238 CONTRIBUTIONS TO GENERAL GEOLOGY the nodules and removed the matrix from the partly this paper is also the first description of a pre-Pleis- exposed fossil (pi. 32, figs. 1, 5). tocene water mite (p. 248). The second nodule was broken in the laboratory, Only two other examples of fossil arthropods that but no fossils were apparent, and the broken pieces can be freed from a matrix are known (Leakey, 1952; were dissolved in formic acid. The resulting residue Strouhal, 1954). The fauna reported by Leakey from showed nothing striking, and the investigation was Lake Tanganyika in Africa has some remarkable about to be abandoned when it was learned that K. E. terrestrial organisms of early Miocene age preserved Lohman, also of the U. S. Geological Survey, had col­ in calcite. Strouhal has described a small fauna of lected nodules from the locality where the dragonfly excellently preserved silicified isopods from late Pleis­ larva was found with the intention of processing them tocene deposits in Austria. for diatoms. Several of these were obtained in hope METHODS AND PROCEDURES of finding more dragonfly larvae, but none were ap­ parent, and these nodules were also treated with formic All but three of the specimens recovered from the acid. The second residue examined had scraps of an fossiliferous calcareous nodules (all dragonfly larvae) animal that was identified as a dytiscid beetle larva. were obtained from insoluble residues prepared with The remainder of Lohman's nodules were then dis­ dilute formic acid (roughly 1 part formic acid to 4 parts solved in search of additional material, and Bassett water or more). The residues were decanted under kindly collected several hundred more nodules from water in a basin from the acid bath into a submerged the vicinity of the original locality. Both of these 100- or 120-mesh screen and rinsed with fresh water to collections yielded many well-preserved fossil arthro­ remove small amounts of calcium formate that might pods. The processing of these nodules continued cake the residue during drying. Each residue was through the spring of 1954, and in August a preliminary dried on