ALAN BR1ND Bre din-Archb old- Smithsonian Biological Survey of Dominica: The Dermaptera Earwigs) of Dominica SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY NUMBER 63 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Insti- tution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge not strictly professional." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Annals of Flight Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to ^oology Smithsonian Studies in History and Technology In these series, the Institution publishes original articles and monographs dealing with the research and collections of its several museums and offices and of professional colleagues at other institutions of learning. These papers report newly acquired facts, synoptic interpretations of data, or original theory in specialized fields. Each publica- tion is distributed by mailing lists to libraries, laboratories, institutes, and interested specialists throughout the world. Individual copies may be obtained from the Smith- sonian Institution Press as long as stocks are available. S. DILLON RIPLEY Secretary Smithsonian Institution SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY NUMBER 63 Alan Brindie Bredin-Archbold- Smithsonian Biological Survey of Dominica: The Dermaptera (Earwigs) of Dominica SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON ABSTRACT Brindle, Alan. Bredin-Archbold-Smithsonian Biological Survey of Dominica: The Dermaptera (Earwigs) of Dominica. Smithsonian Contributions to Zoology, 63, 25 pages, 1971.—An account of the known Dermaptera of Dominica is pre- sented, largely based on material collected during the Bredin-Archbold-Smith- sonian Biological Survey of Dominica. This material is now in the United States National Museum. Of the nine species of the order in the material examined, six are new records for the island, and one of these is described as new. One additional new record for Dominica, based on a specimen in the Manchester Museum, is included, and all known previous records of Dermaptera from the island are given, making a total of thirteen species now known from Dominica. The composition of the Dermaptera fauna of Dominica, and the relation of the various species to other species found in the West Indies, or species found on the mainland of South, Central, or North America, is discussed. A short account of the structure of the male genitalia and the taxonomy of the Dermaptera is included, together with the biology and distribution of the order. Keys to all families or subfamilies of the New World Dermaptera are given, together with keys to, and figures of, all genera and species recorded from Dominica. The figures either show the entire insect, or show the male or female forceps, the structure of the male forceps being one of the most important char- acters in taxonomy. Official publication date is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1971 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 . Price 40 cents (paper cover) Alan Brindle Bredin-Archbold- Smithsonian Biological Survey of Dominica The Dermaptera (Earwigs) of Dominica The Dermaptera form a relatively small, but well- Little is yet known of the biology and ecology of defined order, closely allied to the Orthoptera. the Dermaptera, and such studies as have been Usually three suborders have been recognized— made concern the more well distributed and com- Hemimerina or Diploglossata; Arixenina; and the mon species. The eggs are laid in moist, dark, and Forficulina, although Popham (1961) has presented sheltered situations and parental care on the part a case for ordinal status for the Hemimerina. The of the female is a notable feature. In temperate cli- suborder Hemimerina includes a single genus He- mates the adult stage may be reached after a few mimerus Walker, which is associated with rats of months but this period is probably reduced in the the genus Cricetomys in Africa, and is much different tropics. from the Forficulina in structure. The suborder Adult earwigs are mainly nocturnal, hiding by Arixenina includes the single genus Arixenia Jordan, day under stones, beneath bark, or in other dark which is associated with bats in Indonesia and places, emerging at night to feed. At night some Sarawak, and this genus is considerably different species are strongly attracted to light. Although from the Forficulina. It is the Forficulina which Dermaptera are generally omnivorous, little is cer- represents the Dermaptera as generally understood. tain about the food of most species. The Dermaptera are distinctive by the possession Dermaptera are characteristically tropical or sub- of forceps on the end of the abdomen; these forceps tropical in distribution, and the order reaches its are usually sexually dimorphic, those of the males maximum richness in the equatorial forests of the being much more distinctive than those of the fe- world; the main requirements of the species in gen- males. In the immature stages the forceps are simple, eral appear to be warmth and humidity, and the and resemble those of the females, except in certain percentage of species which are found in arid cli- primitive families in which the forceps of the im- mates is small. Isolated oceanic islands tend to have mature stages are represented by segmented cerci. In a very poor fauna of Dermaptera, but continental the adults, elytra and wings are often present; the islands may support a relatively rich fauna, pro- elytra extend down to about the second abdominal viding that the islands are tropical or subtropical, tergite when fully developed, while the wings, when and are well forested. The Dermaptera fauna of fully developed, are folded beneath the elytra and islands tends to fall into three groups— (1) endemic only the tips project beyond. The description of the species, (2) species common to neighboring coun- wings of earwigs always refers to this exposed portion tries, and (3) cosmopolitan species. The endemic only. When expanded the wings form a quadrant spedes may represent relict forms, or they may have and are supported by radiating veins. developed from a single or successive invasions from neighboring countries; the second group tends Alan Brindle, Manchester Museum, The University, Man- to be more dominant on continental than on oceanic chester 13, England. 1 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY islands; while the cosmopolitan species may be tion of the various species is well summarized. No equally dominant on both oceanic and on con- previous paper on the Dermaptera of Dominica has tinental islands, and tend to supplant the endemic been published, and only six previously recorded species. species have been traced by the present author. In The distribution of Dermaptera largely is con- the present paper a total of thirteen species are re- trolled by climatic conditions, but the present distri- corded from Dominica, of which seven are new to bution of some species appears to be the result of the island. One species is described as new. The accidental introductions into various countries. The present total of species is mainly based on the ma- distribution of earwigs is not necessarily related to terial collected in the present survey, but additional their ability to fly, and the most widely distributed records from the literature have been added, so that earwig is Euborellia annulipes (Lucas), which has the present paper attempts to present a complete neither wings nor elytra, and was originally described account of the Dermaptera of Dominica, as far as from a specimen introduced into the Jardin des yet recorded. Plantes in Paris. Although many species have fully The Dermaptera of Dominica include the fol- developed, and apparently functional, wings, flight lowing three groups—(1) the endemic group, (2) in earwigs is rarely recorded, possibly partly because the American group, and (3) the cosmopolitan of their nocturnal habits. The worldwide distribu- group. tion of the cosmopolitan species seems to be due to (1) THE ENDEMIC GROUP.—The endemic group their habit of hiding in crevices during the day, may be divided into two sections—(a) the species especially in timber or other material which is endemic to the West Indies, and (b) the species transported from country to country by commerce. endemic to Dominica. The importation of plants in particular tends to (a) This section consists of three species—Eu- introduce specimens which are hiding in the basal borellia caraibea Hebard; Marava unidentata leaves or other parts of the plants. Although (Beauvois); and Doru albipes (Fabricius). The first- stringent precautions are now taken in many coun- named species is very closely related to Euborellia tries, such precautions are relatively of modern ambigua (Borelli) and Euborellia janeirensis origin, and it is probably this accidental introduc- (Dohrn), these three species forming a relatively tion by commerce which is at least partly responsible well-defined section of the genus in which the elytra for the wide distribution of the cosmopolitan are short and the wings are not visible. E. janeirensis spedes. These species have a relatively wide has a distribution extending from Brazil northward tolerance of environmental conditions, and intro- to Guyana, but is replaced further north, in Costa ductions may lead to the establishment of the Rica, by E.