Three new fossil phorid flies (Diptera: Phoridae) from ...

NOTE

Three new fossil phorid flies (Diptera: Phoridae) from Canadian Late Cretaceous amber BRIANV. BROWN Department of Entomology, University of Alberta, Edmonton, Alta., Canada T6G 2E3 AND

E. M. PIKE Can. J. Earth Sci. Downloaded from www.nrcresearchpress.com by Renmin University of China on 06/03/13 For personal use only.

Department of Biological Sciences, University of Calgary, Calgary, Alta., Canada T2N IN4

Received November 24, 1989 Revision accepted January 30, 1990 Three new species of Canadian Late Cretaceous amber phorids are described: Prioriphora intermedia, Prioriphora longicostalis, and Prioriphora setifemoralis. A key to the species of the fossil genus Prioriphora is provided, and the paleoecology of the amber sites is discussed. One piece of amber contained an unusually large number (-30) of specimens. Une description est prCsentCe de trois nouvelles espkces de phorides trouvCes dans de I'ambre d'Lge crCtacC tardif, au Canada : Prioriphora intermedia, Prioriphora longicostalis et Prioriphora setifemoralis. Une clC pour les es@ces du genre des fossiles Prioriphora est fournie, et une discussion porte sur la palCoCcologie des sites des dCcouvertes d'ambre. Un morceau d'ambre

contenait un nombre inhabituellement ClevC d'insectes (- 30). [Traduit par la revue] Can. J. Earth Sci. 27, 845-848 (1990)

Introduction Fossils present an unprecedented opportunity to systematists: they allow us to see characters of long-extinct organisms that are potentially direct ancestors of extant species. Insects are plentiful as compression fossils, but most of them are preserved as isolated wings or specimens with crushed and distorted bodies. Many fossils preserved in amber (fossilized tree resin), however, are preserved with startling clarity, such that delicate structures and fine characters such as setal patterns are easily visible. Thus, the discovery of insect inclusions in Canadian Late Cretaceous amber (as discussed by McAlpine and Martin 1969) is exciting, especially as this amber is of such a great age (probably Campanian) . Some of the more interesting insects to come from this amber were the first specimens of cyclorrhaphan flies from the Mesozoic era (McAlpine and Martin 1966). These flies, Sciadophora bostoni and Prioriphora canadambra, although intermediate in form between living Sciadoceridae and living Phoridae, were classified by McAlpine and Martin as Sciadoceridae but were later placed in the Phoridae by Hennig (1973). Since then, there has been some debate on their true affinity (Disney 1985; Grimaldi 1989); we will extend the debate in a future ~ublication.For now. we review information on the paleoecoiogy of the ~anadian'ambersites and describe three new species of Cretaceous Phoridae.

the Belly River Group (equivalent to the Judith River Group of Montana), the Foremost is entirely within the Campanian Stage (Ogunyomi and Hills 1977), which has been dated between 82 and 70-71 Ma ago (Obradovich and Cobban 1975). Foremost sediments were deposited in environments transitional between marine (Pakawki) and continental (Oldman) environments. Coals have been interpreted as being deposited in lagoonal conditions by Ogunyomi and Hills (1977) and probably also in situ (L. V. Hills, personal communication, 1989). Rings in lithified trunks and wood fragments indicate the presence of seasonal cycles. The presence of crocodilians (champsosaurs) suggests a climate warmer than that of present, perhaps subtropical with wet and dry seasons. The Foremost coal swamp appears to have been a barrier-island system separating the marine epicontinental sea from a river-delta lagoon complex reminiscent of the Mississippi River delta. This lagoonal-delta swamp was heavily forested, and it is here that the insects trapped in the amber were flourishing. Apparently, phorid flies were relatively common in this habitat, based on the collection of -30 Prioriphora intermedia n.sp. in a single piece of amber. This large concentration of flies is remarkable, although not unique: Davis (1989) has illustrated two pieces of Dominican amber with -50 and 65 adult Dolichopodidae, respectively.

Stratigraphy and paleoecology Cedar Lake amber was collected from a Holocene beach deposit opposite the mouth of the Saskatchewan River. This deposit has long been flooded by a hydroelectric project and is now inaccessible. The secondary nature of the deposit led to speculation about its primary source (see McAlpine and Martin 1969 for a summary). A Late Cretaceous age is generally accepted, and it is possible that Cedar Lake amber is derived from the same geologic formation as Alberta amber. Alberta, or Medicine Hat, amber is collected from coal tailings derived from within the Foremost Formation. Part of

MATERIAL EXAMINED AND TERMS USED: Through the coopera-

Systematics tion of the curators noted here, specimens were borrowed from the following institutions: (i) Canadian National Collection of Insects (CNC), Biosystematics Research Centre, Agriculture Canada, Ottawa, Ont., Canada KIA OC6 (J. M. Gumming); (ii) Museum of Comparative Zoology (MCZ), Harvard University, Cambridge, MA 02138 U.S.A. (F. M. Carpenter); and (iii) Tyrrell Museum of Paleontology (TMP), Drumheller, Alta., Canada TOJ OYO (P. Johnson). Terms used for structures are those of the Manual ofNearctic Diptera, Vol. 1 (McAlpine 1981), although other interpreta-

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tions of wing venation exist (Disney 1985; Kukalovi-Peck 1983). Prioriphora McAlpine and Martin 1966 TYPE SPECIES: Prioriphora canadambra McAlpine and Martin

Can. J. Earth Sci. Downloaded from www.nrcresearchpress.com by Renmin University of China on 06/03/13 For personal use only.

1966 (by monotypy). DIAGNOSIS: Wing vein Sc distally fused to R,. Fork of wing veins R2+3and R4+5long, much longer than that of living Phoridae. Base of wing vein M1 and M2 reduced or absent. Wing cell cup absent. Proscutellum absent.

SCI. VOL. 27, 1990 TAXONOMIC NOTES: We can propose no synapotypic character states for this genus at this time. We describe the new species in the genus Prioriphora to avoid proposing additional inadequately established genera (see below, Notes on phylogenetic relationships). This genus differs from Sciadophora by the unmodified female terminalia (seen in females of Prioriphora longicostalis n. sp. and Prioriphora setifemoralis n. sp. ) , lack of a proscutellum, and lack of an anepisternal seta. Differences in wing venation and palp shape are no longer useful for separating the two genera.

Key to species of Prioriphorn 1. Hind femur with long seta at mid-length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. setifemoralis n.sp. Only mid-femur with long seta at mid-length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Hind tibia with one posterodorsal seta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. intermedia n.sp. Hind tibia with one anterodorsal and one posterodorsal seta at mid-length, plus one posterodorsal seta betwen mid-length and apex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Mid-tibia with two setae at mid-length; costa short, 0.56 wing length . . . . . . . . . . . . . . . . P. canadambra McAlpine and Martin Mid-tibia with one seta at mid-length; costa long, 0.80 wing length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. longicostalis n.sp.

Prioriphora canadambra McAlpine and Martin 1966 NOTES:We reexamined the holotype of this species (CNC). The wing venation, as given in the original description, indicates that M1is much longer than it should be; it actually fades out before it reaches M2. Furthermore, we were unable to see the sternites mentioned in the original description and figures but were able to discern a wing cell dm (said to be absent by McAlpine and martin 1966). TAXONOMIC

Prioriphora intermedia n. sp. Figs. 1-3 DERIVATION OF NAME:The specific epithet refers to the intermediate length of the costal wing vein in this species. DESCRIPTION: Frons with reclinate anterior interfrontal (or supra-antennal?) setae, one pair of ocellar setae, and two pairs of fronto-orbital setae (Fig. 1). Flagellomere 1 round, large; arista dorsal. Dorsum of thorax with single medial row of acrostichal setae, lateral row of dorsocentral setae, as well as row of long intra-alar setae. Anepisternum undivided. Propleuron with one seta. Notopleuron with three setae. One long postalar seta present. Scutellum with four long setae. Fore femur basally expanded in holotype (Fig. 2) but not in others; mid-femur without long seta; hind femur without long setae. Fore tibia without setae except at apex; mid-tibia with one posterodorsal and one anterodorsal seta at mid-length; hind tibia with posterodorsal seta below mid-length. Mean costal length (n = 8) 0.72 wing length (Fig. 3), range 0.64-0.76. Vein R4+5apically curved. Cell dm present. Seta at base of posterior veins. Structure of terminalia not clear in any specimen. TYPE MATERIAL: The specimens included in this species are considered conspecific because of the matching wing venation and tibial setation. Unfortunately, it is impossible to be sure about the sex of most of these specimens because the genitalia are obscured or the abdomen is shrivelled. HOLOTYPE AND PARATYPE (in a single piece of amber): CANADA: Manitoba, Cedar Lake (Cretaceous) amber, No. 7098 (MCZ). Of the two specimens in the piece of amber containing the holotype, the individual with the wings held vertically (pointing upwards) is the holotype; the specimen with

FIG. 1. Head of Prioriphora intermedia n.sp., holotype.

the wings held horizontally over the body (pointing backwards) is the paratype. OTHER PARATYPES (in amber): CANADA: Alberta, near Medicine Hat, Upper Cretaceous (Foremost Formation), approximately 30 specimens in a single piece of amber, TMP 86-15-1 (TMP); 1 specimen, TMP 82-15-82 (TMP). Prioriphora longicostalis n .sp . Fig. 4 DERIVATION OF NAME: The name refers to the long costa of this species. DESCRIPTION: Female (male unknown). Head and thorax shrivelled, details indistinguishable. Scutellum with two long, thick setae (other two may be broken off). Fore femur without long seta; mid-femur with long, anterior seta; hind femur without long seta; fore tibia with ventral seta basally, above usual tibial spurs; mid-tibia with dorsal seta at mid-length; hind

Prioriphora setifemoralis n.sp. The name refers to the long seta on


DERIVATION OF NAME:

the hind femur. DESCRIPTION: Female (male unknown). Setation of head and thorax impossible to observe, except setae of thorax longer, finer than other species; scutellum with four long setae. Fore femur without long seta; mid-femur with long, anterior seta; hind femur with extremely long (anterior?) seta; fore tibia without long seta; mid-tibia with long anterior seta; hind tibia with anterodorsal and posterodorsal tibia at mid-length. Wing with costa longer than in previous species (approximately 0.90; accurate measurement impossible); we were unable to see basal wing cells and veins. Terminal segments of abdomen unsclerotized, unmodified. HOLOTYPE (in amber): CANADA: Manitoba, Cedar Lake, 1 specimen, No. 6571 (MCZ).

FIG.2. Foreleg of Prioriphora intermedia n.sp., holotype,

R1

Rzt3

R4+5

A,+CUA~ FIG. 3. Wing of Prioriphora intermedia n.sp., one of -30 paratypes in a piece of amber.

/ FIG.4. Wing of Prioriphora longicostalis n.sp., holotype. tibia with anterodorsal and posterodorsal seta at mid-length and posterodorsal seta below mid-length. Wing with costa longer than in the previous species, 0.80 wing length (Fig. 4); wing cell dm absent. Terminal segments of abdomen unsclerotized, unmodified; only cerci clearly visible. HOLOTYPE (in amber): CANADA: Alberta, near Medicine Hat, Foremost Formation, Upper Cretaceous, TMP 82-15-46 (TMP) .

Notes on phylogenetic relationships Given the wide phenetic divergence between P . canadambra and S. bostoni -and the wing venations of the new species are intermediate between both genera - it would be tempting to put these new species in new genera, based on the perceived transition series of the costal lengths from longer (in Sciadophora) to shorter (in Prioriphora). A comparison of the range of variation of costal lengths both within and between living species of Phoridae, however, indicates that erection of such new generic names is definitely unwarranted. In all important character states, these new species fall within a reasonable definition of Prioriphora, although no synapotypic character states can be proposed at this time. Unfortunately, the male tenninalia of most of these flies are hidden by the hind legs or are obscured and can offer little information for classification. The phylogenetic relationships of these flies will be examined in a future paper by the senior author. Acknowledgments We are grateful to Drs. F. M. Carpenter, J. M. Cumming, and P. Johnson for loaning us this interesting material. We would like to thank Dr. L. V. Hills (Department of Geology and Geophysics, University of Calgary) for helpful information and Dr. G. E. Ball (Department of Entomology, University of Alberta) for commenting on an earlier draft of this paper. BVB was partially funded by a Natural Sciences and Engineering Research Council of Canada (NSERC) postgraduate scholarship and an NSERC grant to Dr. G. E. Ball. EMP was supported in part by the Tyrrell Museum of Paleontology and by an NSERC grant to Dr. G. Pritchard (Department of Biological Sciences, University of Calgary). DAVIS, D. R. 1989. An exceptional fossil amber collection acquired by the Smithsonian Institution. Proceedings of the Entomological Society of Washington, 91: 545-550. DISNEY, R. H. L. 1985. Re-interpretation of the wing veins in the Phoridae (Diptera). Entomologist's Monthly Magazine, 121: 55-58. GRIMALDI,D. 1989. The genus Metopina (Diptera: Phoridae) from Cretaceous and Tertiary ambers. Journal of the New York Entomological Society, 97: 65-72. HENNIG, W. 1973. Diptera (Zweifliigler). Handbuch der Zoologie, 4(2), 2/31 (Lfg. 20): 1-337. KUKALOVA-PECK, J. 1983. Origin of the insect wing and wing articulation from the anthropodan leg. Canadian Journal of Zoology, 61: 1618-1669.

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MCALPINE,J. F. 1981. Morphology and terminology - adults. In Manual of Nearctic Diptera. Vol. 1 . Edited by J. F . McAlpine, B. V. Peterson, G. E. Shewell, H. J. Teskey, J. R. Vockeroth, and D. M. Wood. Agriculture Canada, Monograph 27, pp. 9-63. MCALPINE,J. F., and MARTIN,J. E. H. 1966. Systematics of Sciadoceridae and relatives with descriptions of two new genera and species from Canadian amber and erection of family Ironomyiidae (Diptera: Phoroidea). Canadian Entomologist, 98: 527-544. 1969. Canadian amber - a paleontological treasure-chest. Canadian Entomologist, 101: 819-838.

OBRADOVICH, J. D., and COBBAN,W. A. 1975. A time scale for the Late Cretaceous of the Western Interior of North America. In The Cretaceous System in the Western Interior of North America. Edited by W. G. E. Caldwell. Geological Association of Canada, Special Paper 13, pp. 31-54. OGUNYOMI, O . , and HILLS,L. V. 1977. Depositional environments, Foremost Formation (Late Cretaceous), Milk River area, southern Alberta. Bulletin of Canadian Petroleum Geology, 25: 929-968.