Megaxyela langstoni Ross, 1936

Stephan M. Blank, Katja Kramp, David R. Smith, Yuri N. Sundukov, Meicai Wei & Akihiko Shinohara, 2017, Big and beautiful: the Megaxyela species (Hymenoptera, Xyelidae) of East Asia and North America, European Journal of Taxonomy 348, pp. 1-46 : 22-24

Megaxyela langstoni Ross, 1936 sp. rev.

Figs 7A–F , 11E

Megaxyela langstoni Ross, 1936: 131 –132 (♀ ♂, type locality: USA, Mississippi, Starkville, Mississippi State University).

Megaxyela langstoni – Smith 1978: 25 (listed in synonymy with M. major ). ― Smith 1979: 10 (synonymized with M. major ).

Megaxyela major – Smith & Schiff 1998: 644–648 (misidentification, partim). ― Ree 2012: [1] (damage to pecan). ― Ree 2014: [2] (damage to pecan). ― Ree 2016: [2] (damage to pecan).

Type material

Holotype

USA: ♀: “State College Miss. 4/7/32 ”; “ J. M. Langston Collector”; “ Pecan 283813 ”; [red:] “ Holotype Megaxyela langstoni Ross ♀”; “INHS Type #1071”; “ DEI-GISHym 30821 ” (INHS), left posterior leg missing. The locality data correspond with the present-day Mississippi State University of Agriculture and Applied Science in Starkville.

Additional material examined

USA: 1 ♀, Mississippi, Starkville [“ Ag. Coll. Miss. ”], 10 Apr. 1915, C.C. Greer leg., DEI-GISHym 30822 (USNM) ; 1 ♀, Oklahoma, Pawnee County, Pawnee, 352736 East Hwy 64 , 36.292° N, 96.716° W, Malaise trap, 9–23 Apr. 2016, C. Apgar leg., DEI-GISHym 30796 (specimen used for barcoding) (USNM) ; 1 ♀, 1 ♂, Texas (USNM) .

Supplementary description

Female

Synantennomere 3 3.8 mm, filament 0.8 mm, with (6–)8–9 articles. Pulvilli present on metatarsomeres 1–4, on article 1 pulvillus 100 µm long, on article 4 170 µm ( Fig. 7D–E ). See key for additional characters.

Host plant

Pecan ( Carya illinoinensis; cited as “ Carya pecan A. & G.” by Ross 1936) and possibly additional species of Carya ( Dyar 1898b as M. major ; Yuasa 1923 as Megaxyela sp. 1). Supposedly also the photo by Ree (2014) of gregarious larvae of M. ‘ major ’ feeding on pecan refers here.

Remarks

Smith (1978, 1979) treated Megaxyela langstoni as a synonym of M. major . With some reservation, Smith & Schiff (1998) discussed differences in behavior, color and morphology as possible intraspecific variation. Here we reinstate M. langstoni sp. rev. as a valid species. The analysis of the barcoding region of three females, all originating from a collection site in Oklahoma, resulted in two clades (DEI-GISHym 30796 and 30767 + 30797, respectively) separated by a minimum pairwise distance of 13.5%, while the two specimens included in the clade 30767 + 30797 are separated by a mimimum pairwise distance of only 0.3% ( Fig. 2 ). This observation is paralleled by different coloration of the adults corresponding with the type material and the descriptions of M. langstoni and M. major : Specimen 30796 agrees with M. langstoni in the predominantly red brown terga and the basally black pterostigma ( Fig. 7A ), while the specimens 30767 + 30797 agree with M. major in the dorsally predominantly black terga and the unicolorous yellow pterostigma ( Fig. 7G ).

Several specimens included in the type series of M. langstoni were reared from the pecan Carya illinoinensis ( Ross 1936). Ross (1936) also referred to the descriptions of larvae of M. major by Dyar (1898b) and Yuasa (1923). Dyar described the larvae as “gregarious on the young leaves of hickory” [= Carya spec.]. Yuasa (1923) noted “on hickory and pecan”. If the association of larvae described by Yuasa as “ Megaxyela sp. 1” with M. major by J.M. Langston and H.H. Ross is correct, M. major is a “solitary feeder on pecan and some other hickories” ( Ross 1936). Citing M. major , M. langstoni has been listed as a pest of pecan in Texas, but “in most cases sawfly damage is just ‘visual discomfort’ where the larvae have damaged some of the new foliage” ( Ree 2012, 2014). Significant defoliations, which might justify a treatment, obviously are rare ( Ree 2016).

Smith & Schiff (1998) recorded Megaxyela major from 14 states of the eastern US. Collection data from Mississippi completely refer to M. langstoni (type material and additional specimens). We identified additional material from Oklahoma and Texas. For the distribution of M. major , we confirm Kansas (holotype of Odontophyes ferruginea), Texas (lectotype of Xyela major ) and, upon additional specimens studied, also Oklahoma and Pennsylvania. Adults from Florida, Iowa, Missouri, New York and South Carolina need to be re-identified. The state records for Alabama, Arkansas, Georgia, Tennessee and Virginia are based on larvae solely. Since the larvae of four of seven Nearctic Megaxyela are unknown, and Megaxyela larvae generally display only vague specific differences according to our experience with East Asian taxa, these records require scrutiny. Ross (1936) discriminated the larvae of M. langstoni and M. major by the presence of a single large dark area vs pairs of black spots on the pronotum and the penultimate abdominal segment. But these character states might also apply to those Nearctic species of Megaxyela for which the larvae are still unknown.

Figures

Fig. 2. Phylogenetic hypothesis of Megaxyela Ashmead, 1898, based on a Maximum Likelihood analysis of the barcoding region (COI- 5 P) applying the the Jukes-Cantor model. Two specimens of Macroxyela ferruginea (Say, 1824) have been included as outgroup. See Material and Methods for details. Bootstrap values above 50 % are shown next to the concerning nodes. The labels of the individual specimens consist of species name, voucher number (for Megaxyela identical with the DEI-GISHym numbers used in the text, for Macroxyela GenBank accession number), sex (♀ for females, ♂ for males) or larva, country and province of origin, and sequence length.

Fig. 7. A – F. Megaxyela langstoni Ross, 1936, ♀ (A – C = holotype, DEI-GISHym 30821, INHS; D – F = 30822, USNM). G – K. M. major (Cresson, 1880), ♂, paratype (30823, ANSP). A – B. ♀, holotype, habitus dorsal / lateroventral. C. ♀, holotype, head frontal. D – E. ♀, metatarsus, lateral / ventral. F. ♀, abdomen lateroventral. G – H. Habitus dorsal / lateroventral. I. Head frontal. J – K. Metatarsus lateral / ventral.

Fig. 11. Species of Megaxyela Ashmead, 1898, ovipositor sheaths. A. M. euchroma Blank, Shinohara & Wei sp. nov. (holotype, DEI-GISHym 22554, CSCS). B. M. fulvago Blank, Shinohara & Wei sp. nov. (5752, NSMT). C. M. gigantea Mocsáry, 1909, holotype of M. mikado Sato, 1930 (22350, NSMT). D. M. inversa Blank & D. R. Smith sp. nov., paratype (22356, USNM). E. M. langstoni Ross, 1936, holotype (30821, INHS). F. M. parki Shinohara, 1992 (18510, NSMT). G. M. pulchra Blank, Shinohara & Sundukov sp. nov., holotype (18501, NSMT). H. M. togashii Shinohara, 1992, holotype (22352, NSMT). Images not to the same scale.