Hymenoptera: Xyelidae) in North America
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16 October 1998 PROC.ENTOMOL.SOC.WASH. 100(4), 1998, pp. 636-657 THE GENERA MACROXYEU KIRBY AND MEGAXYELA ASHMEAD (HYMENOPTERA: XYELIDAE) IN NORTH AMERICA D AVID R. S MITH AND N ATHAN M. SCHIFF (DRS) Systematic Entomology Laboratory, PSI, Agricultural Research Service, U.S. Department of Agriculture, % National Museum of Natural History, MRC-168, Washing- ton, DC 20560, U.S.A. (e-mail: [email protected]); (NMS) U.S. Department of Agriculture, Forest Service, Southern Hardwoods Laboratory, PO. Box 227, Stoneville, MS 38776, U.S.A. (e-mail: [email protected]). Abstract.-Five species of Megaxyela, including Megaryela alzkonae, n. sp., and two species of Macroxyela occur in North America. Macroxyela bicolor MacGillivray is a new synonym of Macroxyela ferruginea (Say). The species are keyed, described and illustrated, and biological information is summarized. Hosts include hickory, pecan, and elm. Key Words: Megaxyela, Macroxyela, Xyelidae, Ulmus, Carya, pecan, North America The large xyelids of the genera Megax- for Xyelidae, he suggested that Megaxyela yela and Macroxyela are among the most and Macroxyela form a natural unit based intriguing groups of sawflies because of on wing venation and that Xyelu Dalman, their odd appearance, scarcity, and probable Neoxyela Curran (= Xyela) and Pleroneura primitive status in the Symphyta and Hy- Konow form a separate closely related menoptera. They are apparently two relic group. Smith (1967) proposed a classifica- genera in a family with a long fossil record tion based on larval and adult characters (Rasnitsyn 1969). Megaxyela occurs only in and concluded that Macroxyela and Megax- eastern Asia and eastern North America, yela form the tribe Macroxyelini in the sub- and Macroxyela only in North America. family Macroxyelinae. The other tribe of Larvae of both genera are associated with Macroxyelinae, Xyeleciini, includes Xyele- angiospermous trees, whereas all other cia Ross, a genus found in western North Xyelidae are associated with conifers. They America and Japan. are seldom collected, although Macroxyelu We have accumulated about 600 speci- ferruginea (Say) can be collected in num- mens of the genera Megaxyela and Ma- bers on its host during its flight time. Why croxyelu and are now able to resolve some Megaxyela is so scarce is puzzling. Such questions and present a more complete pic- large (lo-15 mm long) and colorful insects ture of species composition in North Amer- with long hindlegs (Fig. 3) certainly should ica. We recognize five species of Megaxyela be sighted more frequently by collectors. and two species of Macroxyela. Both genera were revised by Ross Specimen depositories and acronyms (1932), but few specimens were available used are in Acknowledgments. w to him, and he was not able to resolve sex associations or present a complete concept T RIBE M ACROXYELINI of the North American fauna. Although he The Macroxyelini differ from other Xye- did not use subfamily or tribal categories lidae by wing venation (Figs. 4-6): forewing VOLUME 100. NUMBER 4 637 Figs. I-2. Clypeus and labrum. 1, Megaxyela aviingrata. 2, Macroxyela ferruginea. with vein Rsl; C free from SC forming costal (Fig. 1); forewing with Sc2 joining SC + Rl ‘/4 and subcostal cells; vein Sc2 distinct; Sc2 to % distance between separation of Rs and stigma (Fig. 4); labial palpus 4-segmented C joining S + Rl apical to separation of Rs; Megaxyela hindwing with two closed submarginal cells Clypeus with small anterior median notch and (1Rs and 2Rs) (wing venation terminology labrum broad, rectangular, and nearly truncate follows Goulet and Huber 1993). Also, the anteriorly (Fig. 2); forewing with Sc2 joining apical filament of the antenna is short, one- SC + RI very slightly apical to juncture of Rs with SC + Rl (Figs. 5, 6); labial palpus 3.seg- quarter to one-third the length of the thud mented Macroxyela segment, and 5-l 1 segmented, and the tarsal claws have a long inner tooth, nearly as long G ENUS MEGAXYELA ASHMEAD as the outer tooth. Megaxyela Ashmead 1898: 214.-Ross K EY TO G ENERA OF M ACROXYELINI 1932: 161-164 (N. Amer. species; syn.: 1. Clypeus with large median triangular tooth and Odontophyes, Paraxyela).-Ross 195 1: 7 labrum rounded with notch on anterior margin (N. Amer. catalog).-Smith 1978: 24 638 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON (world catalog).-Smith 1979: 10 (N. with clearly defined serrulae at its apex Amer. catalog).-Shinohara 1992: 783- (Figs. 22-29). 786 (Asian species). Type species: Xyela Known host plants are members of the major Cresson. Orig. desig. Juglandaceae. The hosts for the North Odontophyes Konow 1899: 42. Type spe- American Megaxyela aviingrata (Dyar) cies: Pleroneura aviingrata Dyar. By and M. major (Cresson) are Carya spp. monotypy. and perhaps Juglans spp. The hosts for M. Megaloxyeta Schulz 1906: 88. Emendation. gigantea in eastern Asia are Juglans spp. Paraxyelu MacGillivray 1912: 294. Type and Pterocarya spp. (Shinohara 1992). species: Xyelu tricolor Norton. Orig. desig. The few known aspects of their biology is given under each species. A brief account Clypeus with sharp, median triangular of M. gigantea in Korea by Sato (1941), tooth and labrum rounded with anterior, as given by Shinohara (1992), is note- median notch (Fig. 1); labial palpus 4-seg- worthy in that it contains some unusual mented; forewing with SC long, Sc2 joins habits for sawflies: “This species has a Sc+Rl % to ‘/z distance between the sepa- univoltine life cycle, with adult appear- ration of Rs and stigma. Antenna1 flagellum ance from late April to early May. The 6-l 1 segmented. General habitus of all spe- female lays an egg along the midrib on cies similar to that of M. alisonae, n. sp. the upper surface of the apical part of a (Fig. 3). newly growing leaf. Before oviposition, Few specimens are available for study, the female stands on the under surface of but we have seen enough (about 65) to the leaf, with the head directing toward resolve several problems, including spe- the base of the leaf. Then the female cies identity and association of sexes, and bends the tip of her abdomen to the upper present a better understanding of the surface of the apex of the leaf and ovi- North American fauna. We recognize five posits there, folding by hind legs the apex species. of the leaf in half along the midrib upward The genus occurs only in eastern North and attaches the folded halves with glu- America and eastern Asia. Shinohara tinous material. One egg is laid per leaf. (1992) treated three species from eastern The larval period is from late May to ear- Asia, M. gigantea Mocsky from eastern ly June. The larva always starts feeding Russia (Primorski Krai), Korea, and China; from the apex of the leaf and coils on the M. togashii Shinohara from Japan; and M. midrib at rest. The larva has four molts parki Shinohara from Korea. and overwinters in the soil.” Two species groups are apparent. The Asian species and Megaxyela major, M. K EY TO N EARCTIC S PECIES OF MEGAXYELA uviingratu, and M. alisonae from North Legs black or orange brown, usually with hind- America form one group characterized by tarsus white 2 the short sheath with the ventral and dorsal Legs bright orange with hindtibia and tarsus margins curving mesally to an acute apex black or hindtibia black and hindtarsus white 3 (Figs. 7-9) a thick hindbasitarsus (Fig. 15) Entirely black except for white hindtarsal seg- ments 225 or 3-5; sheath about 2.5X longer the lance lacking dorsal teeth, and the lancet than broad (Fig. 8) aviingruta (Dyar) having indistinct serrulae (except M. alison- Usually entirely orange brown, sometimes var. ae) (Figs. 16-19). The other group includes ious black markings on dorsum of head, tho- the North American Megaxyela tricolor and rax, and/or abdomen and on femora and tibiae; M. bicoloripes, which have a long sheath, sheath about 3X longer than broad (Fig. 7) major (Cresson) straight on its ventral margin (Figs. 10, 1 l), Thorax black; sheath longer than hindtarsus, a slender hindbasitarsus (Fig. 14), the lance about 4X longer than broad (Fig. 11) (legs with with distinct teeth at its apex, and the lancet hindtibia and hindtarsus black; hindbasitarsus VOLUME 100, NUMBER 4 639 Fig. 3. Habitus of Megaqela alisonae, length 12 mm. slender, as in Fig. 14, about 6.5X longer than Megaxyela alisonae Smith and Schiff, broad) tricolor (Norton) new species Thorax black with mesostemum and mesepi- sternum orange; sheath shorter than hindtarsus (Figs. 3, 9, 15, 20, 21) and less than 3X longer than broad (Figs. 9, 10) . ..___.....__.. 4 Female.-Length, 10.5-12.0 mm. Anten- Hindtarsal segments 2-5 white; hindbasitarsus na black with scape brownish. Head black slender, about 6.5X longer than broad and tar- with clypeus, labrum, mouthparts, and man- sal segments 2-4 much longer than broad (Fig. dible white, tips of mandibles brownish, 14); sheath at apex in lateral view nearly straight below, slightly emarginate on dorsum and apical labial palpal segment blackish. (Fig. 10) hicoloripes (Rohwer) Thorax orange with pronotum, mesonotum, Hindtarsal segments 2-5 black; hindbasitarsus and upper corners of mesepisterum and me- broad, about 3.5X longer than broad and tarsal sepimeron black to purplish metallic; pos- segments 2-4 about as long as broad (Figs. 15); sheath at apex in lateral view emarginate terolateral portion of pronotum sometimes on both dorsal and ventral margins (Fig. 9) dark orange; mesonotal lateral lobe may be . alisonae, new species partly orange; tegula white. Abdomen or- 640 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON Fig. 4. Wings of Megmyla major. ange, terga with narrow black posterior greatly amused by her brother’s (NMS) margins; apical tergum black or about half choice of an entomological career.