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NovitactesAMERICAN MUSEUM PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3205, 9 pp., 2 figures August 29, 1997 A Pulicid Flea in Miocene Amber from the Dominican Republic (Insecta: Siphonaptera: Pulicidae) * ROBERT E. LEWIS1 AND DAVID GRIMALDI2 ABSTRACT A new species of flea, Pulex larimerius, is de- its genus is found throughout the Western Hemi- scribed on the basis of a complete female speci- sphere and contains one species known to be a men in Miocene amber from the Dominican Re- cosmopolitan pest. The six described, extant spe- public. Although at least eight other, exceptionally cies of Pulex feed on a great variety of mamma- rare fleas are known from Dominican amber, the lian hosts, and even a species of bird. The pres- ones that have been studied all belong to the Rho- ence of five strands of hair in the amber with the palopsyllidae. The specimen described here is flea virtually confirms the mammalian host of the unique as the only known fossil in the Pulicidae; fossil. INTRODUCTION Amber is renowned for the exquisite pres- ment in tree resin: midges that swarmed too ervation of small organisms that became en- close to the tree trunk, ants that scurried trapped in it millions of years ago when it along the tree trunk, stingless bees that har- was sticky resin. Most life forms in amber vested the resin for their nests. As one might had habits (based on inference from modern expect, ectoparasitic arthropods are extreme- relatives) for which we would expect entrap- ly rare in amber, as they are in any fossil * Journal Paper No. J-16752 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa; Project 3100. I Professor Emeritus, Department of Entomology, Iowa State University, Ames, IA 50011-3222. Present Address: 2906 Stone Brooke Circle, Ames, IA 50010-4174. 2Chairman and Curator, Department of Entomology, American Museum of Natural History. Copyright X American Museum of Natural History 1997 ISSN 0003-0082 / Price $1.60 2 AMERICAN MUSEUM NOVITATES NO. 3205 deposit. We report one such exceptional fos- in the Staatlichmuseum fur Naturkunde, sil here, in lower Miocene amber from the Stuttgart (photo in Grimaldi, 1996: 115) and Dominican Republic. the other three in private collections. These Fossil fleas, or presumed fleas, have been appear to be rhopalopsyllids as well. Poinar previously reported from Baltic amber as (1992) reported, based on unpublished work well as several sedimentary deposits. Pa- by Traub, that even though most extant rho- laeopsylla klebsiana Dampf, 1911, and Pa- palopsyllids feed on rodents and marsupials, laeopsylla dissimilis Peus, 1968, were de- morphological features of the three speci- scribed from Baltic amber. According to mens studied by Traub indicate that they Larsson (1978) and Poinar (1992, 1995b), were bird parasites. The only living members these two species belong to the family Hys- of this family that are avian ectoparasites be- trichopsyllidae, but Palaeopsylla, a primitive long to the genus Parapsyllus, most of which genus with 49 living species, is now assigned are found on burrow-nesting sea birds in the to the hystrichopsylloid family Ctenophthal- Southern Hemisphere. A few specimens of midae. The species in this genus are mainly Listronius robertsianus (Jordan, 1938) have parasites of insectivores and are restricted to been taken from penguin nests in the Falk- the Palearctic Region. Fleas in Baltic and land Islands. Poinar (1995b) later changed Dominican amber are the only known Terti- his view, arguing that the Dominican amber ary fossils, although there are five Creta- rhopalopsyllids had capromyid rodent hosts. ceous taxa that are presumptive fleas or per- Birds did exist in the Dominican amber haps closely related to the order Siphonap- forests, and various rare feather inclusions tera (Lewis and Grimaldi, in prep.). have been reported by Poinar (1992) and Dominican amber is known for the great Grimaldi (1996). In fact, one feather in the variety of organisms preserved in it, perhaps Smithsonian collection has been identified, even more diverse than the Oligocene/Eo- on the basis of microscopic features of the cene Baltic amber that has been studied for barbules, to be from a piculet woodpecker (Layboume et al., 1994). centuries (Larsson, 1978). The age of Do- An incredible aspect of the piece of amber minican amber has been unnecessarily con- we are reporting on here is the presence of fused. An Oligocene and Eocene age (30-40 five strands of fine hair, obviously of mam- Ma) has been given by Poinar (1992, 1995a, malian origin. Although this is not definitive 1995b), but stratigraphic information indi- proof that the hair came from the host of the cates that this amber is actually Miocene flea, the conclusion is unavoidable, based on (Grimaldi, 1995; Iturralde-Vinent and the taxonomic position of the fossil and the MacPhee, 1996). Fossils belonging to 24 or- probability of its preservation. Fleas are ex- ders of insects are known from Dominican tremely rare in Dominican amber, with only amber, including such small and rare orders eight specimens known from approximately as Zoraptera (Poinar, 1992; Grimaldi, un- 300,000 pieces of amber (1: 30,000 or 1:3 publ.). No mallophagan or anopluran lice X 104). Hair is also very rare in amber. One have been found thus far, nor have bird and of us (Grimaldi) has found only three pieces bat flies (Hippoboscidae, Nycteribiidae, and containing hair in approximately 100,000 Streblidae), but extremely rare ticks occur in pieces of amber screened over the last ten this amber (Poinar, 1992; Grimaldi, 1996) years (1: 30,000 or 1: 3 X 104). The likeli- and even rarer are the fleas. hood of a flea and hair strands being captured Poinar (1992) mentioned three fleas stud- simultaneously, by chance alone, is incon- ied by R. Traub, all of which are reported to ceivably remote: approximately 1 in 108. belong to the Rhopalopsyllidae; two in the Surely this fossil flea fed on a mammal, Traub collection, the other in the United which would make it the only known fossil States National Museum, Smithsonian Insti- flea preserved with remnants of its host. tution. Since then, Poinar reported (1995b) another rhopalopsyllid, identified by R. E. SYSTEMATICS Lewis as Rhopalopsyllus sp. That specimen Genus Pulex is in Poinar's personal collection. There are Pulex. Linnaeus, 1758. Syst. Nat., 10th ed., I: 614 at least four more unstudied specimens: one (in Europa, America). 1997 LEWIS AND GRIMALDI: FLEA IN AMBER 3 TYPE SPECIES: P. irritans Linnaeus, 1758, not until 1958 that the name was finally res- by subsequent designation by Baker, 1904. urrected by Smit. From 1908 to 1958 all GENERIC DIAGNOSIS: Anterior margin of North American collections were assigned to head smoothly rounded or slightly angled, P. irritans. Though the two species are prac- frontal tubercle absent or inconspicuous. Eye tically impossible to separate in the females present, reduced in P. sinoculus, never sin- and differences in the males are virtually uate or with an internal sinus. Antennal cla- cryptic, they do show some differences in vus asymmetrical, its dorsal margin folea- host preferences that allow us to at least cious. Labial palpi four-segmented. Some speculate about the true nature of the records species with vestigial genal comb of one or reported during the 50 years that P. simulans two spines per side. Pronotal comb absent. was not acknowledged to be a valid species. Mesothoracic pleural rod absent. Metanotum First, P. simulans is restricted to the West- and first abdominal tergite of about equal ern Hemisphere where it is known from Flor- length dorsally, or the former slightly longer ida, west and north to southern Alberta and than the latter. Spiracle of metepimeron larg- British Columbia in North America, south to er than abdominal spiracles. Tarsal segment the northern half of Brazil and northern Chile V of all legs with four pairs of lateral plantar in South America. Haas and Wilson (1967) bristles, the space between pairs three and reported this species from Hawaii. It parasit- four wider than that between pairs one and izes a broad range of hosts (Didelphis [Di- two and two and three. Inner surface of hind- delphimorphia], Canis, Mephitis, and Uro- coxae with row or patch of short, spiniform cyon [Carnivora] Spermophilus [Rodentia], bristles. Sensilium with 14 pits per side. Bul- and Odocoileus [Artiodactyla]) but it seems ga of female spermatheca globular. Not all of to be primarily a parasite of prairie dogs (Cy- these characters are visible in the fossil spec- nomys [Rodentia]) and other burrow-dwell- imen. ing hosts. It occurs at the lower elevations in COMMENTS: The flea specimen we describe Central and South America and is replaced here is unusual in that it not only belongs to by P. irritans at higher altitudes, as pointed the Pulicidae, it is also a member of an extant out by Hopla (1980), but sufficient material genus: Pulex. This genus is indigenous to the to analyze the distribution is not available at Western Hemisphere, with one species, P. ir- this time. Both Hopla (1980) and Smit ([for- ritans, found throughout the world. It is merly curator of Siphonaptera at the British sometimes divided into two subgenera, each Museum of Natural History] personal com- with three species. The species of (Juxtapu- mun. to Lewis) are of the opinion that this is lex) are P. alvarezi Barrera, 1955, from the a complex genus and that there are a number Central American tapir (Perissodactyla); P. of undescribed South American species al- echidnophagoides (Wagner, 1933) from lied to P. simulans that must be studied be- southern Costa Rica from armadillos (Xe- fore it can be accurately delineated.