THOMAS W. DONNE SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • 1969 NUMBER 37 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 37 Thomas W. Donnelly The of Dominica British West Indies SMITHSONIAN INSTITUTION PRESS CITY OF WASHINGTON I97O ABSTRACT Donnelly, Thomas W., The Odonata of Dominica, British West Indies. Smithsonian Contributions to Zoology, 37: 1-20, 1970.—The Odonata fauna of Dominica is, for the first time, treated in detail. Twenty-one species of dragonflies and damselflies are recorded with detailed locality records and ecological notes, and a key is provided to 37 species known or expected to occur in the Lesser Antilles. Scapanea archboldi, new species, is described, and the nymphs of Protoneura ailsa Donnelly and Argia concinna Rambur are described for the first time. Aeshna psilus Calvert and Telebasis sanguinalis Calvert are recorded from the Lesser Antilles for the first time. Contribution No. 162, Entomology Section, Division of Plant Industry, Florida Department of Agriculture, Gainesville. 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 : 1970 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 35 cents (paper cover) Thomas W. Donnelly The of Dominica British West Indies The Archbold-Bredin survey of the island of Dominica The locality near Portsmouth is the swampy area has provided an almost unparalleled opportunity for near East Cabrit. Here are found grassy, shallow ponds the close examination of the flora and fauna of a and tree-lined sloughs along a dirt road. All of these small, tropical island. The collection of dragonflies bodies of water have a temporary appearance but are and damselflies (Odonata) amassed during this survey probably permanent. Hodge (1954) records 113 inches represents one of the most complete collections of Lesser of rain for the year 1948 at Portsmouth, with only one Antillean Odonata ever assembled. The 20 species col- month (April) having less than 4 inches. Several lected (plus an additional species reported by Dr. D. C. species (Micrathyria didyma, M. aequails, Telebasis Geijskes) include 2 species reported from the Lesser sanguinalis) are far more common here than else- Antilles for the first time, and an additional new where, and Lestes forficula has been recorded on species. Dominica only from this locality. This report is based on the examination of 846 The most important locality near the coast of west- specimens collected by 16 individuals over a period of central Dominica is in the vicinity of Clarke Hall, approximately 3 years, with collection dates falling on where a variety of habitats have been collected rather 89 days of the calendar year, and thoroughly repre- thoroughly. The small shaded stream at Cafe, across senting all months of the year except for July, August, the Layou River from the estate house, has a sandy to and December. In addition, a list of Odonata collected rocky bottom, moderate flow, and abundant emergent by D. G. Geijskes has been included. The author spent vegetation. Enallagma coecum and Protoneura ailsa the first week of June 1964, collecting on the island in are particularly abundant here. the company of Oliver S. Flint, Jr. Several small streams in the central upland region, Although 40 specimen localities are included in this along the main road across the island, where collected report, and although these localities occur in seven out repeatedly. These streams are almost entirely above of the ten parishes of Dominica, the areal coverage of 1,000 feet in elevation, and are characteristically rocky, the island is uneven. The principal collecting localities more or less swift, and have only limited emergent have been in the vicinity of Portsmouth, along the vegetation. They have a limited Odonata fauna, con- west-central coast (from the Layou River to Roseau sisting mainly of Dythemis sterilis, Argia concinna, and especially around Clarke Hall), along small and Protoneura ailsa. streams in the central uplands of the island, and in the Freshwater Lake is a high-elevation (2,365 feet), vicinity of Freshwater Lake. There are very few collec- abundantly vegetated lake of moderate size (one- tions from the windward coast, and none from the quarter mile across). It appears to be Dominica's only southwestern coast. really salubrious Odonata locality which is appreciably away from the coast. Three species (Anax concolor, Thomas W. Donnelly, Department of Geology, State Univer- sity of New York, Binghamton, New York 13901 and Research Brachymesia furcata, and Scapanea archboldi, new Associate, Florida State Collection of Arthropods, Florida species) have been recorded only from this locality, Department of Agriculture, Gainesville. and Aeshna psilus is known elsewhere only from one 1 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY collection of a nymph. There are two areas which are rainfall histograms for two localities, and collection especially favorable for Odonata: the shallow water histograms for two Odonata species. These figures have fringing the lake proper and the small outlet stream. In been constructed using only data from nonspecialists spite of the fact that clouds hang over this lake almost in order to minimize a possibly biased sample during constantly during much of the year, and the rainfall the author's week of active collecting. is heavy, Anax can be seen flying at almost any time. Most of the species that have been collected more than a few times do not have a conspicuous seasonal Climate distribution pattern. A few species, however, deserve comment. Erythrodiplax umbrata, the most widespread Dominica is the wettest of the Antillean islands, with Odonate on the island, occurs commonly during both no really dry region of the island or part of the year. the early and late months of the year. There are rela- Hodge (1954) summarized the climate thoroughly, tively few collections during the late part of the "dry" noting that for one year (1948) the mean rainfall of 22 season. In addition to the records represented by the stations was 137 inches. The windward part of the histogram (Figure 3), the author did not find this island had a mean of 126 inches, the leeward part 103 species conspicuous during his collections in the first inches, and the central part of the island 186 inches. week of June 1964. If the species is truly less common The minimum rainfall recorded by Hodge was 68 at this time, it might be suggested that there are either inches (leeward side) and the maximum 250 inches two semi-distinct univoltine populations of this species (center of island). Doubtless greater and lesser rainfalls on Dominica—one flying during the dry season and one occur. Rainfalls, especially in the wetter months, are during the wet, or one bivoltine population. There is generally torrential, interspersed with periods of misty no clear geographical distinction between records of rain referred to locally as "liquid sunshine." Figure 1 the two time groups. The flight period of the adults is shows monthly rainfall histograms for 1948 from two probably a few weeks at the most, and, although the localities: Riverdale (center of the island), with a 250- time required for nymphal development is not known, inch rainfall, and Roseau (on the leeward side), with most smaller tropical libellulines require less than a a 79-inch rainfall (taken from Hodge, 1954). Tem- year to complete the development from egg to adult. peratures are moderate (yearly average 79°F) and The species Orthemis ferruginea (Figure 4) has a relative humidities, especially in the interior, are very quite different pattern. There are relatively few rec- high. ords for this species during the later