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THE DISTRIBUTION AND RELATIVE ABUNDANCE OF THE SIBLING SPECIES ORTHEMIS FERRUGINEA (FABRICIUS, 1775) AND O. DISCOLOR (BURMEISTER, 1839) IN NORTH AND MIDDLE AMERICA (ANISOPTERA: LIBELLULIDAE) Dennis R. Paulson
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Slater Museum of Natural History, University of Puget Sound, Tacoma, WA, 98416, U.S.A E-mail: Available online: 28 Mar 2012
To cite this article: Dennis R. Paulson (1998): THE DISTRIBUTION AND RELATIVE ABUNDANCE OF THE SIBLING SPECIES ORTHEMIS FERRUGINEA (FABRICIUS, 1775) AND O. DISCOLOR (BURMEISTER, 1839) IN NORTH AND MIDDLE AMERICA (ANISOPTERA: LIBELLULIDAE), International Journal of Odonatology, 1:1, 89-93 To link to this article: http://dx.doi.org/10.1080/13887890.1998.9748094
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International Journal of Odonatology I (1): 89-93, 1998. © 1998 Backhuys Publishers.
THE DISTRIBUTION AND RELATIVE ABUNDANCE OF THE SIBLING SPECIES ORTHEMIS FERRUGINEA (FABRICIUS, 1775) AND 0. DISCOLOR (BURMEISTER, 1839) IN NORTH AND MIDDLE AMERICA (ANISOPTERA: LIBELLULIDAE) Dennis R. Paulson Slater Museum of Natural History, University of Puget Sound, Tacoma, WA 98416, U. S. A.,
[email protected]
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Received 24 Feb 1998; revised 23 June 1998; accepted 1 July 1998
Abstract The sibling species Orthemis discolor and 0. ferruginea are distinguished by coloration, although one structural characteristic can be used to differentiate many females. Further information on the distribution and relative abundance of the two species in North and Middle America is presented.
Introduction
Orthemis ferruginea (Fabricius, 1775) has long been known as one of the most conspicuous odonates throughout the Neotropical region. When I was in Costa Rica in 1966-67, I noted the puzzling situation that the females occurred in two rather different morphs, with heavily marked and unmarked thorax, respectively. But I was unable to detect two types of males and went no further with speculation. De Marmels (1988) cleared up the mystery. The individuals with marked thorax are 0. ferruginea, a more northerly species, while those with unmarked thorax are 0. discolor (Burmeister, 1839), a more southerly species. From examination of specimens in the National Museum of Natural History and his own collection, Donnelly (1995) further clarified the differences between the species and presented a range map showing the distribution of the two species from the southern United States to northern South America. I recently examined my mainland specimens of "0. ferruginea" and was able to sort them easily into these two species, thereby gaining more information about them. Structural difference between the species Neither De Marmels (1988) nor Donnelly (1995) were able to find structural characters to differentiate the two species, but the vulvar lamina appear to differ slightly. In 0. discolor, the two halves of the lamina typically meet at a very slight angle (a very shallow V), while in 0. ferruginea, the meeting place is usually straight (a wide U with short arms). However, in some females of both species, the lamina forms a shallow arc; these females would be indistinguishable by this characteristic. (Fig. 1)
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Northernmost records of 0. disolor Two specimens of 0. discolor were collected in Texas two decades ago and were recently discovered by examination of collections. These are the only records north of the Mexican border. One is from Palmetto State Park, Gonzalez Co., 20 Oct 1976, S. W. Dunkle (SWD collection) (Dunkle 1998), the other from a stream 2.4 miNE Round Top, Fayette Co., 17 Aug 1977, D. R. Paulson (DRP) (Paulson 1998). Both are immature males, with no trace of markings on the thorax; the specimen in my collection appears identical with other immature males from throughout the range of the species. These localities, in the triangle formed by San Antonio, Austin, and Houston, are well north of the southern tip of the state, from which most tropical odonate records have come. Another northerly record is from Rio Purificaci6n at Barretal, Tamaulipas, Mexico, 800', 25 Jun 1965, D. R. Paulson (DRP). This site, north of Ciudad Victoria, is on a desert river, and the other seven species collected there all occur in Texas. Clearly, all collections of Orthemis from southern Texas should be scrutinized for additional specimens of the species.
Occurrence in middle America The map in Donnelly (1995) shows 17 localities for ferruginea and 13 for discolor in Mexico, but ferruginea is much the more widespread and common species in that country (Table 1). 0. discolor is common, however, at least in parts of Veracruz and Chiapas (Table 1). Specimens in my collection show sympatry at three sites in Mexico: around San Andres Tuxtla, Veracruz, where a total of 10 discolor and 1 ferruginea were taken during several months in 1961 by 1. A. Harshaw; at a pond 2.7 mi S La Tinaja, Veracruz, 14 Aug 1965, D. R. Paulson, where a teneral ferruginea was taken and a larva collected from which a discolor emerged (indicating syntopy); and a forest pond at Uxmal, Yucatan, 16 Nov 1983, D. R. Paulson, where 2 discolor and 1 ferruginea were taken. Both species occur throughout Central America, 0. ferruginea south only to Costa Rica. Specimens from Central America in my collection include the following (number of discolor followed by number of ferruginea): Belize 0-2, Guatemala 8-2, El Salvador 0-2, Honduras 1-0, Nicaragua 0-1, Costa Rica 106-97, and Panama 1-0. My southernmost specimen extends the range of ferruginea slightly beyond the map in Donnelly (1995). It is from pond at airport, 1 mi E San Vito, 3300', Puntarenas Prov., Costa Rica, 13 Mar 1969, D. R. Paulson. This site is only about 10 kilometers from the Panamanian border. Otherwise, all my Costa Rican specimens of ferruginea are from the lowlands of Guanacaste Province (Table 2). Most of the Guanacaste specimens come from a 14-month intensive study of the dragonflies of Hacienda Taboga, in the Tempisque River valley, where I collected specimens at random throughout the study; thus the relative abundance of the species is indicated by the specimen sample. 0. discolor is common throughout Costa Rica (Table 2), up to about 4,000 feet in elevation. I can reconstruct no differences in their ecology based on my records from their sympatric occurrence at Taboga, but the seasonal distribution may be somewhat different there. 0. ferruginea is common throughout the year, while 0. discolor may be found primarily in the rainy season, May-November (Fig. 1).
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discolor
ferruginea
Fig. 1. Vulvar lamina of 0. ferruginea and 0. discolor
Table 1. Specimens of Orthemis discolor and 0. ferruginea in D. R. Paulson collection from Mexico. The states are ordered roughly from north to south.
discolor
Sonora Sinaloa Durango Nuevo Leon Tamaulipas San Luis Potosi Nayarit Jalisco Colima Veracruz Puebla Oaxaca Tabasco Campeche Yucatan Quintana Roo Chiapas
TOTAL
0 0 0 0 1 0 1 0 0 11
0 1 0 0 3 0 7 24
ferruginea 1 6 1 2 2 2
3 4
3 6 1 3 1 1 3 2 4
46
92 Table 2. Specimens of Orthemis discolor and 0. ferruginea in D. R. Paulson collection from Costa Rican provinces.
discolor
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Guanacaste Puntarenas Alajuela Heredia San Jose Cartago Limon
ferruginea
26
96
24 14 18 1
1
16 7
20 18 16 14 Ill c 12 Ill E 10 8 (/) 6 4 2 0
l
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