Novitate MUSEUM vitates PUBLISHED BY THE AMERICAN CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. Number 3127, 8 pp., 13 figures, 1 table MUSEUM OF NATURAL HISTORY 10024 April 6, 1995 A Remarkable New Species of Ogcodes (Diptera: Acroceridae) in Dominican Amber DAVID GRIMALDI! ABSTRACT Four specimens of a distinctive new species of acrocerine fly are described as Ogcodes exotica, preserved in Oligo-Miocene amber of the Domin- ican Republic. The fossil species appears most closely related to several Old World species of Ogcodes, based on distinctive, clavate hind tibiae and tergal mounds (structure of the antennae and wing venation unquestionably places it in the cos- mopolitan genus Ogcodes). However, features of its cervical region are found in the African genera Meruia and Sabroskya. INTRODUCTION The family of obligate internal parasitoids of spiders, the Acroceridae, is one of con- trasts. Although the family has only 500 known species and 50 genera, its morphology is exceptionally diverse. It is undoubtedly a monophyletic lineage, based not only on the distinctive life history, but also on a suite of morphological characters: adult flagello- meres fused into a single flagellum; lower ca- lypter extremely large; and a wing membrane with very fine pleating. Woodley (1989) grouped the acrocerids with the nemestrinids on the basis of hypermetamorphosis. Ne- mestrinid larvae are also parasitoids (but on grasshoppers and beetles). The bee flies (fam- ily Bombyliidae) have the same life history. Nemestrinids were described by Rohden- dorf (1968), in Jurassic sediments of Russia, so this would imply that the acrocerids are equally ancient, based on sister-group dating. In fact, an acrocerid has been described from the same Jurassic beds of Karatau (Ussat- chov, 1968), but the preservation of Archo- cyrtus gibbosus is not complete, especially for the head. The venation of Archocyrtus is most similar to that of certain acrocerines, es- pecially Acrocera, but there are some features unlike any found in living members of the 1 Associate Curator and Chairman, Department of Entomology, American Museum of Natural History. Copyright © American Museum of Natural History 1995 ISSN 0003-0082 / Price $1.20 family. Huge gaps exist in the fossil record: the next oldest fossils are in the Baltic amber from the upper Eocene-lower Oligocene, ca. 40 million years old (Hennig, 1966, 1968). In a family of such apparent antiquity, a fossil from the Oligo-Miocene (25-30 million years old) contributes little toward under- standing basal relationships. Rather, the im- portance of such a young fossil provides in- formation on the origins and stasis of species- level taxa, and biogeography. Amber from the Dominican Republic lies in marine sediments northeast of Santiago, in extensively uplifted terrain. The only mine to have been stratigraphically dated (with benthic Foraminifera) is the Palo Alto mine, dated as 23 million years old (Baroni-Urbani and Saunders, 1980). Since the amber obvi- ously does not lie in its original milieu, this is a Minimum age, although it can safely be assumed that the age is hardly greater than this. MATERIALS AND METHODS Most Dominican amber specimens avail- able for study to the scientific community are purchased from dealers, who themselves ac- quire the specimens from the campesinos who mine the material. With the exception of a few dealers, virtually all of the amber pieces become mixed, so that it is nearly impossible to trace the source of an amber piece to one of dozens of mines. The exception is that the light, soft “‘copal‘* from the eastern mines (Bayaguana, Cotui) is easily distinguished from the darker, heavily polymerized mate- rial (true amber) from the hills surrounding Santiago. Chemical fingerprinting, using py- rolysis-gas chromatography, has not revealed any consistent differences among amber from the different mines. Thus, the best and most conservative estimate is that any true Do- minican amber is approximately 25 million years old. Certainly, published claims (e.g., Scarbrough and Poinar, 1992) that particular fossils sold commercially originate from the La Toca mines (based simply on color) and are, therefore, Eocene in age, have virtually no basis. Methods for preparation, micro- scopic examination, and photography of the amber specimens are given in Grimaldi (1993). Morphological terminology follows AMERICAN MUSEUM NOVITATES NO. 3127 that established in the Manual of Nearctic Diptera; wing vein nomenclature follows that of Hennig (1968). Length of the wing was taken from the very base of the wing to the tip. ACKNOWLEDGMENTS Thanks are extended to Dieter Schlee and Ettore Morone, for loaning specimens of O. exotica in their care; to Norman Woodley (USDA/SEL) and Evert Schlinger for original discussions on the placement of this bizarre species; and to Manuel Perez and Jake Brod- zinsky, for allowing me to sort through their amber fossil caches. NSF grant BSR 9020102 funded the field and laboratory work on Dip- tera living in the Caribbean and those fos- silized in Dominican amber. David Barra- clough kindly lent the types of Sabroskya. He, Norman Woodley, and Evert Schlinger pro- vided helpful critiques of the manuscript. DESCRIPTION Ogcodes exotica, new species Figures 1-4, 10-13 DIAGNOsIs: Thorax relatively small and not extremely arched; distinct cervical region present; abdomen slender (not dorsoventral- ly flattened), abdominal tergites 2—5 each with a central mound, bearing tuft of fine, erect setae (e.g., figs. 2, 4); venation typical of Ogcodes, with crossvein m-cu present; hind tibia clavate, with apical half enlarged to 3— 4x diameter of proximal end. Proboscis ves- tigial. Known from four males. DESCRIPTION: Measurements: see table 1. Head: Ocellar triangle slightly raised, me- dian ocellus lost. Dorsal margins of eyes con- tiguous to level of antennae; hind margin of eye with slight indentation, dorsal and ven- tral facets undifferentiated in size. Proboscis vestigial. Antenna with long, thin flagellum having slightly swollen apex; apical setulae unapparent; antennae situated ventrally, al- most near oral margin. Thorax: Distinct cervical region present, this area not hidden behind the head; posi- tioned between enlarged postpronotal lobes. Postpronotal lobes widely separated. Meso- notum not strongly arched; with black me- 1995 GRIMALDI: OGCODES IN DOMINICAN AMBER 3 Figs. 1-3. Photomicrographs of Ogcodes exotica, n. sp. 1. AMNH DR 8-88. 2. Morone Coll. no. 853. 3. Holotype, AMNH DR-11-8. 4 AMERICAN MUSEUM NOVITATES NO. 3127 Fig. 4. Habitus illustration of holotype, AMNH DR-11-8. dian stripe and several rows of fine, erect ac- rostichal setae that increase in length poste- riad. Posterior rim of scutellum with similar fine, erect setae. Legs slender. Hind tibia cla- vate, the diameter of the apical half 3-4 that of the proximal half; with numerous fine, stiff setulae on short, tubercular bases. Claws and pulvilli large. Wing with fine pleating typical of acrocerids; costal vein extended to tip of wing, slight swelling where vein R, + meets costal vein. Vein R,,, with slight kink, not quite reaching posterior margin of wing. Crossvein r-m slanted strongly anteriad; in- complete, not reaching vein M3. Vein M, in- complete: not reaching wing margin, present only as a fold at level of crossvein r-m. Apex of vein M, not reaching margin of wing; crossvein m-cu present, well developed. Vein Cu meeting anal vein before wing margin, forming a long triangular cell, cup. Abdomen: Rather long and slender, with tergites 2—S each raised with central mound bearing tuft of long, fine, erect setae. Apical tergite also with tuft of long, fine setae. Color pattern seen on Stuttgart specimen, as shown in figure 11. Genitalia observed on two spec- imens, as figured (figs. 12, 13): Distiphallus arrowhead-shaped. Types: Holotype: AMNH DR-11-8, a male in a drop-shaped piece of clear yellow amber from Dominican Republic, 16 <x 10 mm (figs. 3, 4). Paratypes: AMNH DR-8-88 (fig. 1), in a large chunk of yellow amber, with several unpolished surfaces; Staatliches Museum fiir 1995 GRIMALDI: OGCODES IN DOMINICAN AMBER R) ppl cervical ( < sclerite a Figs. 5-8. Comparative structures on extant Acroceridae. 5—7: Sabroskya palpalis (holotype). 5, 6. Head and anterior portion of thorax (lateral view, 5; dorsal view, 6). ppl, postpronotal lobe. 7. Wing. 8. Wing, Ogcodes clavatus. Drawing based on a specimen in the Smithsonian Institution from Naivasha, Kenya. The dotted r-m crossvein was not observed in this specimen but it was reported as present in a specimen from Pretoria, South Africa (Schlinger, 1960a: fig. 11). A trace of r-m was reported (Schlinger 1960b: pl. 3, fig. 10), in probably the same specimen as this one from Naivasha. 6 AMERICAN MUSEUM NOVITATES gonostylus aedeagus tergite 9? NO. 3127 b & RE RRS se see > IIo ra * re! ORK ratetet Aeieete este wo tatete e XZ SBC 22505 Ry AN rare et ( —— SS 0.1 mm Figs. 9-13. Features of Ogcodes exotica (figs. 10-13) and O. clavatus (fig. 9). 9, 10: Hind tibiae. 11. Dorsal view of Stuttgart paratype (DO-5374-H), showing color pattern and position of tergal mounds. 12, 13: Male genitalia. 12. Morone collection, no. 853. 13. Holotype, AMNH DR-11-8. Naturkunde, Stuttgart DO-5374-H (17 x 9 mm); Morone Collection no. 853(private), in a hemispherical piece 12 x 14 mm. ETYMOLOGY: From the Greek, exotikos, meaning from the outside, alien, foreign, and exotic; in reference to its apomorphic features and apparent Old World relationships. RELATIONSHIPS The fossil species is unequivocally placed into the genus Ogcodes, on the basis of the following characters: antennal flagellum with a slight apical swelling (plesiomorphically there is no swelling); antenna located ven- trally, near the oral margin (a feature also occurring in Sabroskya, Meruia, and some other acrocerines); mouthparts (proboscis and palps) absent or vestigial; eyes bare (dense pilosity is plesimorphic and widespread among Acrocerinae); venation highly re- duced, such that crossvein r-m is incomplete or entirely absent, and vein M, is incomplete 1995 (not reaching the wing margin or to level of crossvein r-m) (e.g., fig. 8). In fact, several apomorphic features of O. exotica link it with a few Old World species. The clavate hind tibia is found in O. clavatus Becker (from South and East Africa) and O. respersus Séguy (from northern China). I was able to compare the hind tibia of the fossil only with clavatus (based on a specimen in the Smithsonian Institution from Naivasha, Kenya [H.J.A. Turner, coll., 4-40, C.LE. 12838]). The hind tibia in clavatus is not as abruptly swollen as in exotica (cf. figs. 9, 10), and clavatus also has a cervical region more | extended than in other Ogcodes (but not to the extent seen in exotica). Ogcodes clavatus, however, has the stout abdomen typical of virtually all Ogcodes, and it lacks tergal mounds. Only three Ogcodes species, in fact, have mounds on the tergites: O. hirtus Sack (from Iran) with “‘bituberculate swellings on tergites I-IV” [Schlinger, 1960b: 271]), O. guttatus Costa (widespread from South Af- rica to Italy and India), and O. orientalis Schlinger (from Cambodia) (with tergites II and III swollen in the middle). From the cur- sory accounts of O. hirtus and O. orientalis, the tergal mounds are fewer than in O. exo- tica, and they are certainly not bituberculate in the fossil. Tergal mounds are common in some philopotine acrocerids, such as Oligo- neura. This subfamily has a suite of features plesiomorphic to the Acrocerinae, so this dis- GRIMALDI: OGCODES IN DOMINICAN AMBER 7 TABLE 1 Measurements (in mm) of Ogcodes exotica Specimens Total Thorax Wing length length length AMNH DR-11-8 5.08 1.55 3.73 AMNH DR-8-88 5.05 1.50 3.75 M-853 5.33 1.68 4.33 DO-5374-H 6.21 1.96 4.65 tinctive character has arisen several times in the family. Likewise, the widely separated postpronotal lobes and protrudent pronotal collar seen in the fossil are certainly conver- gent with what is seen in Sabroskya (e.g., pal- palis, figs. 5, 6) and Meruia. In virtually every other respect, such as eye pile, well-devel- oped mouthparts (fig. 5), and the complete wing venation (fig. 7), Sabroskya and Meruia are plesimorphic with respect to the fossil and other Ogcodes. The Acroceridae are notorious for rarely being encountered. Thus, it is uncertain if species of Ogcodes similar to the fossil will be found living in the Western Hemisphere. At present, the only definitive relationships of the fossil are with Oriental and African species. This is a biogeographic connection that is slowly emerging with the study of or- ganisms fossilized in Dominican amber. REFERENCES Baroni-Urbani, C., and J. B. Saunders 1980. The fauna of the Dominican Republic amber: the present status of knowledge. Proc. Ninth Caribbean Geological Conf. (Santo Domingo, Aug. 1978), pp. 213- 223. Grimaldi, D. 1993. The care and study of fossiliferous am- ber. Curator 36: 31-49. Hennig, W. 1966. Spinnenparasiten der Familie Acrocer- idae im Baltischen Bernstein. Stuttgart- er Beitr. Naturkd. 165: 1-21. 1968. Ein weiterer Vertreter der Familie Ac- roceridae im Baltischen Bernstein (Dip- tera: Brachycera). Stuttgarter Beitr. Na- turkd. 185: 1-6. Rohdendorf, B. B. 1968. New Mesozoic nemestrinids (Diptera, Nemestrinidae), Jn B. B. Rohdendorf (ed.), Jurassic insects of Karatau, pp. 180-189. Moscow: Academiya Nauk SSSR. Scarbrough, A. G., and G. O. Poinar, Jr. 1992. Upper Eocene robber flies of the genus Ommatius (Diptera: Asilidae) in Do- minican amber. Insecta Mundi 6: 13-— 18. Schlinger, E. 1960a. A review of the South African Acrocer- idae (Diptera). Ann. Natal Mus. 14: 459- 504. 1960b. A revision of the genus Ogcodes La- treille, with particular reference to spe- 8 AMERICAN MUSEUM NOVITATES NO. 3127 cies of the Western Hemisphere. Proc. Woodley, N. E. U.S. Natl. Mus. 3429: 227-336. 1989. Phylogeny and classification of the “Or- Ussatchov, D. A. thorrhaphous*“ Brachycera. Jn J. F. 1968. New Jurassic Asilomorpha (Diptera) McAlpine (ed.), Manual of Nearctic fauna from Karatau. Entomol. Rev. 47: Diptera, 3: 1371-1395. Research Branch 617-628. Agriculture Canada Monograph no. 32. Recent issues of the Novitates may be purchased from the Museum. Lists of back issues of the Novitates, Bulletin, and Anthropological Papers published during the last five years are available free of charge. Address orders to: American Museum of Natural History Library, Department D, Central Park West at 79th St., New York, N.Y. 10024. TEL: (212) 769-5545. FAX: (212) 769- 5009. E-MAIL: scipubs@amnh.org This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).