Macronyssidae in wild bird nests in Mexico, including new synonymies, and the genus Pellonyssus in the new world (Acari: Mesostigmata)
Frank J. Radovsky1 and María Luisa Estébanes-González2
1 Department of Entomology, Oregon State University, 2046 Cordley Hall, Corvallis, Oregon 97331, U.S.A.
2 Instituto Biología, UNAM, Apartado Postal No. 70-153 D.F. CP. 04510 MEXICO.
Recibido: 6 de marzo 2000 ]]> Aceptado: 18 de octubre 2000
RESUMEN
Pellonyssus nidicolus Baker, Delfinado, and Abbatiello, 1976 es un nuevo sinónimo de Pellonyssus reedi (Zumpt y Patterson, 1952). La sinonimia de Pellonyssus passeri Clark y Yunker, 1956 con P. reedi se mantiene. Los ejemplares de Pellonyssus reportados por Estébanes-González (1997) son identificados aquí como pertenecientes en parte a P. reedi y en parte a P. marui Yunker y Radovsky, 1966, es el primer reporte de estas especies en México. La tercera especie identificada de Pellonyssus conocida en el Nuevo Mundo es un parásito de colibrís Pellonyssus gorgasi Yunker y Radovsky, 1966, previamente reportado de México. Las claves para identificación de hembras, machos y protoninfas de estas 3 especies se incluyen. Un carácter común se da para comparar rasgos distintivos de las hembras de 9 especies validas de Pellonysssus en el mundo. La subespecie Ornithonyssus sylviarum utrechtensis Micherdzinski, 1980 es sinonimizada con la subespecie nominal O. s. sylviarum (Canestrini y Fanzago, 1877).
Palabras clave: Pellonysus, Ornithonyssus, Macronyssidae, pájaros silvestres, México, Nuevo Mundo, ácaros, parásitos.
ABTRACT
Pellonyssus nidicolus Baker, Delfinado, and Abbatiello, 1976 is relegated to the status of a junior synonym of Pellonyssus reedi (Zumpt and Patterson, 1952). The synonymy of Pellonyssus passeri Clark and Yunker, 1956 with P. reedi is sustained. The Pellonyssus specimens reported by Estébanes-González (1997) are identified here as belonging in part to P. reedi and in part to P. marui Yunker and Radovsky, 1966, the first records of these species in Mexico. The third identified species of Pellonyssus known in the New World is a parasite of hummingbirds, Pellonyssus gorgasi Yunker and Radovsky, 1966, previously reported from Mexico. Keys to identify the females, males, and protonymphs of these 3 species are given. A character grid is given to compare features of females of the 9 valid species of Pellonyssus in the world. The subspecies Ornithonyssus sylviarum utrechtensis Micherdzinski, 1980 is synonymized with the nominal subspecies O. s. sylviarum (Canestrini and Fanzago, 1877).
Key Words: Pellonyssus, Ornithonyssus, Macronyssidae, wild birds, Mexico, New World, mites, parasites.
]]> INTRODUCTION
Estébanes-González (1997), in reporting on mites that she found in the nests of wild birds in Mexico, identified the Pellonyssus specimens that were collected as P. nidicolus Baker, Delfinado, and Abbatiello, 1976. Radovsky (1998), in reviewing the known species of Pellonyssus, overlooked P. nidicolus. Further study of the material identified by Estébanes-González (1997) shows that it comprises 2 Pellonyssus species. Because of our uncertainty about the validity of P. nidicolus, we examined the relevant type material. In this paper, we establish the new synonymy of P. nidicolus under P. reedi (Zumpt and Patterson, 1952), comment on other reported synonymies relating to P. reedi, provide further information for the separation of Pellonyssus species, and reassign collections of Pellonyssus reported by Estébanes-González (1997) to P. reedi and Pellonyssus marui Yunker and Radovsky, 1966, both species reported from Mexico for the first time. We also synonymize Ornithonyssus sylviarum utrechtensis Micherdzinski, 1980 under the nominal subspecies and include the specimens identified by Estébanes-González (1997) as O. s. utrechtensis in O. s. sylviarum.
MATERIALS AND METHODS
The senior author has held material for study of all valid Pellonyssus species but one (Pellonyssus tillae Cort, 1974, from South Africa), in nearly all cases from the type collection or that had been compared with the holotype (Radovsky, 1998). For the current study, the holotype and only specimen of P. nidicolus, inadvertently omitted by Radovsky (1998), and the holotype of Pellonyssus passeri Clark and Yunker, 1956 were borrowed; the Mexican material reported by Estébanes-González (1997) was restudied; and additional Pellonyssus material from the eastern U.S.A. was obtained.
Ornithonyssus sylviarum series from Mexico, the U.S.A., and Europe were examined.
All measurements are in micrometers.
RESULTS
Pellonyssus reedi (Zumpt and Patterson, 1952)
]]> Synonymy:Steatonyssus reedi Zumpt and Patterson, 1952, J. Entomol. Soc. S. Afr., 15:163.
Steatonyssus malurus Womersley, 1956, Proc. Linn. Soc. N.S.W., 80:214.
Pellonyssus passeri Clark and Yunker, 1956, Proc. Helminthol. Soc. Wash., 23:94.
Pellonyssus nidicolus Baker, Delfinado, and Abbatiello, 1976, J. N. Y. Entomol. Soc., 84:56, New Synonymy.
Baker et al. (1976) based their description of P. nidicolus on a single female specimen found in an unidentified bird's nest at Farmingdale, Long Island, New York, on 30 June 1973. The description is mostly in general terms, and the length and width of the body are the only measurements given. The "coxal spur formula" was specified as 1-2-2-1; those numbers must refer to the coxal setae, of which 1 on coxa I was evidently overlooked in counting (although shown in figure). The chelicerae and dorsal and ventral views of the idiosoma were illustrated. The authors wrote: "P. nidicolus is distinguished from all other species of Pellonyssus by the large contiguous dorsal plates bearing uniformly long and strong dorsal setae; the large anal plate, and the uniformly long and strong ventral setae on the integument of the idiosoma."
Examination of the holotype of P. nidicolus shows artifacts of mounting, specifically blistering of the integument, that are identical to those shown in the illustrations included with the original description, and so we conclude there have not been significant changes in the appearance of this specimen since it was described and illustrated. There are not any qualitative characters mentioned in that description or that we find in reexamining the holotype to separate it from P. reedi. The measurements in Table 1 support the close similarity of the P. nidicolus type to the paratype of P. reedi from the type collection and a range of other P. reedi- assigned specimens from South Africa and elsewhere. Those measurements include the shields and setae that Baker et al. (1976) cited as distinguishing P. nidicolus from other species in the genus.
Till (1964) published a scholarly revision of Pellonyssus that continues to be the primary source for information on the genus. She was first to report the synonymy of P. passeri under P. reedi, apparently based on the literature only. Our comparison of the holotype of P. passeri with a paratype from the same collection as the holotype of P. reedi, as well as other material from South Africa, sustains her conclusion. Comparison of other material from South Africa, Mexico, and the eastern U.S.A. adds more weight to her interpretation.
]]> Till (1964) had paratypes of P. malurus from Australia on hand when she put that name in synonymy under P. reedi. We follow her decision, as have other authors (Micherdzinski, 1980, Domrow, 1987). However, it should be noted that she was tentative regarding this synonymy. She stated that the Australian mites differ from typical P. reedi in having the first pair of sternal setae about 3X as long, the sternal shield relatively narrow, and the anal shield relatively short. She wrote, "However, two groups of mites from birds in Bechuanaland... combine the features of P. reedi and P. malurus.... [I]t has been decided, for the present to consider these differences to be within the range of intraspecific variation." Her conclusion is plausible from a zoogeographic standpoint, in that (1) other macronyssids associated with volant hosts appear to have achieved a distribution including South Africa and Australia without human assistance, e.g. the bat parasite Ichoronyssus miniopteri (Zumpt and Patterson, 1952); and (2) the house sparrow (Passer domesticus) is a common host of P. reedi and has become nearly cosmopolitan, partly as a result of human transport.The collections presented as P. nidicolus by Estébanes-González (1997) are reassigned as follows:
MEXICO: Temamatla, Hirundo rustica, 11/8/85, Ornithonyssus sylviarum (Canestrini and Fanzago, 1877); P. reedi. MORELOS: Jonacatec, Columbina inca, 20/2/86, P. marui. Jojutla, Las Huertas, Leptotila verreauxi, 6/4/86, P. marui. 4 km. N Alpuyeca, Columbina passerina, 19/10/85, P.marui. Cuernavaca, Buenavista, Hirundo rustica (nest abandoned), 22/10/85, P. marui. MICHOACAN: Zinapécuaro, Campylorhynchus gularis, 21/6/88, P. marui. DISTRITO FEDERAL: Cd. Universitaria, Passer domesticus, 28/4/86, P. reedi. Zona Sur, Amazillia beryllina, 1/9/96, P. gorgasi (nest).
Figures 1-6 show the opisthonotal shield and the sternal shield of each of the 3 species of Pellonyssus found in the New World. The labelling of the penultimate seta on the opisthonotal shield is here Z4, changed from Radovsky (1998) (where given as S5) due to a reevaluation of the chaetotaxy as part of a general revision of the Macronyssidae. Text references to Z4 in Radovsky (1998) can be similarly corrected to Z3. A text reference in that paper to J5 as being present on the protonymphal pygidial shield is a lapsus calami and should read Z5.
Keys to the females, males, and protonymphs of the 3 New World species of Pellonyssus are given below, all 3 now known from Mexico. Table 2 is a matrix of characters that will help in distinguishing females of all 9 species of Pellonyssus that are recognized as valid at present.
Ornithonyssus sylviarum (Canestrini and Fanzago, 1877)
Estébanes-González (1997) recorded O. sylviarum, at the species level, from the nests of 3 different birds in 3 passeriform families, including Catharus occidentalis (Muscicapidae) from Huitzilac in Morelos. She also noted 3 females of O. sylviarum utrechtensis Micherdzinski, 1980 in the nest of Turdus migratorius (Turdidae) at the same location in Huitzilac. We consider O. s. utrechtensis to be, and here designate it as, a junior subjective synonym of the nominal subspecies O. s. sylviarum, New Synonymy. Micherdzinski (1980) stated that O. s. utrechtensis is distinguishable from the nominal subspecies by the presence of only 2 (rather than 3) setal pairs on the caudal portion of the dorsal shield. He applied this designation to the type series of 6 females, taken from a domestic canary (Serinus canarius, family Fringillidae) in Utrecht, the Netherlands.
The genus Ornithonyssus is primarily found in the Western Hemisphere, with only a few species having an Old World presence through transport in post-Columbian times (Furman and Radovsky, 1963). A subspecies is usually defined geographically, as a distinctive population occupying part of the range of a species. Subspecies of parasites are also sometimes described as limited to a particular host. Basing a subspecies on individuals associated with a domestic host in one location on the Eurasian continent is contrary to the usual definition. The subspecies concept is based on the idea of a restriction of gene flow between the named population and other populations of the species. For animal groups in general, it has not been intended historically that the formal application of a subspecies trinomial be used for intrapopulation variants (Mayr 1982), in this case potentially restricted to a single locality (within Utrecht) and a single host (the introduced Serinus canarius).
O. sylviarum exhibits reduction in the setae on the caudal margins of the dorsal shield, relative to other Ornithonyssus, through the loss of the penultimate setal pair (S5), leaving only 3 pairs (Z3, Z4, Z5), of which Z4 is much reduced as in the genus as a whole (Figs. 7-9). Population samples of O. sylviarum typically show variation in the presence of setae of 2 of the 3 remaining pairs, especially Z4 but also Z3. For example, in the 10 females seen from a nest of Carpodacus mexicanus in Auburn, Alabama in the eastern U.S.A., 3 are missing Z4 on 1 side, 1 is missing Z4 on both sides, and 1 is missing Z3 on 1 side.
Finding mites with the defining characteristic of O. s. utrechtensis (Z3 absent, Z4 and Z5 only present) on Turdus migratorius in Mexico further supports the conclusion that the specimens in the type series on Serinus canarius in Utrecht are intrapopulation variants and do not represent a separate subspecies.
ACKNOWLEDGMENTS
We greatly appreciate the loan of materials from the following: Jeffrey K. Barnes and the New York State Museum, Albany; the National Museum of Natural History, Washington, D.C.; Magdalena K.P. Smith Meyer and the ARC-Plant Protection Research Institute, Pretoria; W. Calvin Welbourn and the Florida State Collection of Arthropods, Gainesville; Gary R. Mullen and Andrew Stoehr, Auburn University, Alabama; and Lynn Royce, Oregon State University, Corvallis.
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Till, W.M. 1964. A revision of the genus Pellonyssus Clark and Yunker (Acari: Mesostigmata). J. Linn. Soc. (Zool.) 45:85-102. [ Links ]
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