23. Arthropods Inhabiting Rodent Burrows in. the Karakum Desert VICTOR A. KRIVOKHATSKY Abstract Communities of arthropods were studied in the Repetek Reserve (Karakum Desert) in burrows of desert rodents Rhombomys opimus, Spermophilopsis leptodactylm, Meriones meridianus, and M. libycus. These burrows differ in complexity and structure of arthropod communities. More than 500 species of burrow-inhabiting arthropods possessing various degrees of ecological specialization were discovered, from obligate bothrobionts to species only accidentally found in burrows. Taxonomic composition of the burrow arthropod communities is discussed as well as their trophic, temporal, and spatial structure. Introduction Animal burrows and holes contain peculiar ecosystems. In addition to their hosts, these burrows are often inhabited by many other animal species, predominantly arthropods, which are usually called "bothrobionts" or "nidicoles." Here, we refer to a community of an animal burrow as a "heterotrophic burrow consortium." Its core includes the host(s) of the burrow and its nonliving part, the burrow itself. Other animals in this consortium have ecological connections of various degree with its core. The term "bothrobiont," currently used in the morphological-ecological classifications of ecosystems, designates any animal that lives in the holes or burrows, digs its own burrow, and has morphological and ecological adaptations to these conditions. We use the following classification system for animals found in burrows: (1) bothrobionts - species with permanent (obligatory) burrow connections; (2) bothrophiles - species with a strong burrow connection; (3) bothroxenes - species with no obligatory connections; and (4) species alien to the burrow, and only accidentally found there. Studies of burrow ecosystems started in Europe early in this century (Falcoz 1915). In the former USSR, extensive studies were done by Vysotskaya in V. Fet & K.I. Atamuradov (eds.), Biogeography and Ecology of Turkmenistan, 389-402. © 1994 Kluwer Academic Publishers. Printed in the Netherlands. 390 Victor A. Krivokhatsky Russia (1953-1978) and Chilkilevskaya in Belorussia (1965-1982). In Middle Asian deserts, research on burrow consortia was started by Ya. Vlasov (or; Vlassov) (1932-1941, Central Karakum Desert) and continued by E. Nelzina ; and her colleagues in the Kizylkum (Nelzina 1966, 1971, 1977; Nelzina et al. 1978) and the author (from 1981 to 1989) in the East Karakum. f In the sand desert, many animal species dig burrows as shelters from external j conditions and as protection from predators. Mammals which dig only? permanent complex burrows include the large gerbil, Rhombomys opimus I Licht., the ground squirrel, Spermophylopsis leptodactylus Licht.; some gerbils j of the genus Meriones (e.g., M. meridianus Pall, and M. libyens Licht.); fox] (Vulpes vulpes L.); and hedgehog (Hemiechinus auritus Gmel.). Some mammals J do not dig their own holes but rather occupy previously made burrows: these f include the active desert predator Vormela peregusna Güld., which uses gerbil burrows after eating the host. Even some birds, such as Oenanthe isabellina . Temm. and Athene noctua Scop., build their nests in gerbil burrows. Many,; lizards, snakes, and tortoises also use previously made burrows as shelters from i extreme temperatures in summer and during the winter months. Numerous ; species of arthropods living in desert conditions strictly inhabit the complex rodent burrows. In the Karakum Desert, arthropod communities of the burrow were studied in detail in two localities: in the southern part of the Central Karakum near Ashkhabad (Vlasov 1932, 1933, 1937a,b, 1941; Vlasov and loff 1937; Vlasov \ and Miram 1937; Vlasov and Kirichenko 1937; Vlasov and Sychevskaya 1937; Vlasov and Shestoperov 1937; Vlasov and Stackelberg 1937) and the Repetek Reserve, in the East Karakum (Krivokhatsky 1981, 1982a,b, 1983, 1984, 1985a,b, 1987,1989; Krivokhatsky and Fet 1982; Krivokhatsky and Kashcheev 1983). During these studies, more that 500 species of burrow-inhabiting arthropods possessing various degrees of ecological specialization were discovered. Materials and Methods The original research was conducted by the author in the Repetek Reserve, Turkmenistan, from 1978 to 1988. More than 60,000 specimens of Arthropoda, predominantly insects, were studied. Arthropods were collected from rodent burrows (Rhombomys opimus, Spermophilopsis leptodactylus, and Meriones meridianus) using a number of techniques. One of the methods used (total of 5,600 samples) was extraction of material from the holes using a spoon-like shovel with a long handle and a sieve (a modification of the Shiranovich method). Another technique was installation of burrow traps (glass cylinders filled with formalin) inside and outside of each burrow entrance (a modification of the Barber method of pitfall traps). A total of 850 traps were installed, and invertebrates were sampled every three hours. Additional collecting techniques included light trapping and hand collection. Arthropods Inhabiting Rodent Burrows in the Karakum Desert 391 Fig. 1. Part of the large gerbil burrow (Repetek, February 1979): 1 - entrances, 2 - holes, 3 - feeding and nesting chambers, 4 - depth of the holes, 5 - surface. Environment in the Rodent Burrows Types of burrows in the Karakum Desert range from the simple and temporary to the complex and permanent. For example, jerboas dig summer burrows which are used only for one day. These holes are destroyed the next day and lack any bothrobionts. Next in complexity follow the burrows of gerbils, Meriones spp., and the ground squirrel Spermophilopsis leptodactylus. These burrows are permanent, but not complicated. The most complex is the burrow of the large gerbil, Rhombomys opimus. It has two to three levels and a number of holes, passages, and chambers (Fig. 1). The microclimate of R. opimus burrows has been the object of detailed studies (Shiranovich et al. 1965). The temperature in the holes was found to be equal to that of the soil temperature at the same depth. Seasonal and daily fluctuations of the burrow temperatures are less than those on the soil surface. Humidity in the burrow is higher than in the air; it depends on the presence of the animals and decayed food supply, and on the regime of ventilation. Burrows of the large gerbils are peculiar but widespread desert habitats; many desert animals (arthropods as well as vertebrates) cannot exist outside of these burrows. 392 Victor A. Krivokhatsky Table 1. Taxonomic and ecological composition of burrow consortia in the Repetek Reserve 1 8 _ _ Isopoda 1 1 _ _ 100 Scorpiones 4 1 2 1 - 15 Pseudoscorpiones 4 3 - 1 - 20 Solifuga 4 - 1 2 1 10 Aranei 40 12 13 8 6 1 1,180 Gamasoidea 3 - - - 3 1,000 Ixodoidea 6 - 2 2 2 1,500 Myriapoda 1 - - - 1 9 Insecta: 261 106 46 32 58 18 18,730 Collembola 2 - - 2 - 10,000 Protura 1 1 - - - 6 Thysanura 3 1 2 - - 100 Blattodea 4 1 1 - 2 2,240 Orthoptera 6 4 - 1 1 212 Psocoptera 1 1 - - - 10 Homoptera 6 6 - - - 28 Hemiptera 29 29 4 2 4 834 Coleoptera 121 33 31 20 34 3 2,498 Aphaniptera 11 - - - 11 1,670 Neuroptera 3 - - 1 2 75 Hymenoptera 50 32 3 3 2 10 432 Diptera 8 - 3 1 1 3 500 Lepidoptera 15 8 2 1 2 2 124 Vertebrata: 22 2 3 2 15 1,520 Reptilia 10 - 1 - 9 500 Mammalia 9 - 2 1 6 1,000 Aves 3 1 - 2 - 20 Total 345 124 67 49 86 19 25,075 1 - taxonomic groups, 2 - total number of species sampled from the burrows, 3 - alien species, 4 - bothroxenes, 5 - bothrophiles, 6 - bothrobionts, 7 - undetermined species, 8 - total number of animals sampled. Morphological Structure of the Burrow Arthropod Communities Morphological structure of a burrow consortium is characterized by classifi- cation of arthropod inhabitants according to their taxonomic composition, trophic level, and distribution. Taxonomic Structure The list of arthropod groups found in the rodent burrows in the Karakum Desert is given in the Table 1. below, we give a brief review of large systematic groups, which include Crustacea (Isopoda), several classes of Arachnida (Scorpiones. Pseudoscorpiones, Solifuga, Aranei, Acariformes, and Parasitiformes), Myriapoda, and various orders of Insecta. Arthropods Inhabiting Rodent Burrows in the Karakum Desert 393 Isopoda. In the large Asiatic sawbug genus Protracheoniscus, only one species, P. orientalis Ul., lives in the sandy deserts. This species can dig its own holes only in the moist sand (in Repetek, inside gerbil burrows). Scorpiones. These are not obligatory bothrobionts and live in natural cavities in the sand desert. Some species, however, such as Mesobuthus eupeus (C.L. Koch) and Orthochirus scrobiculosus (Grube) are commonly found in gerbil burrows. Pseudoscorpiones. Among the false scorpions there is an ecological group living in caves, bird nests, and burrows. In the Karakum Desert such species as Olpium pallipes Luc. and Geogarypus shulovi Beier are obligatory bothrobiontes. Solifuga. Solpugids Galeodes fumigatus Walter and G. turcomanicus Birula can use burrows as shelters during the day. This group needs more taxonomic study. Aranei. Some spider families include many bothrobiont and bothrophile species. In Repetek Reserve, these include Minosia karakumensis Spassky, Berlandina afghana Denis, and Minosiella intermedia Denis (Gnaphosidae); Theridium varians Hahn., Steatoda grossa (C.L. Koch), and Latrodectus tredecimguttatus (Rossi) (Theridiidae); Artema transcaspica Spassky (Pholcidae); Micaria sp. (Micariidae); Hersiliola sp. (Hersiliidae); Zodarion raddei Simon (Zodariidae); Evippa onager (Simon)