Megaxyela inversa Blank & D.R. Smith

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: 19-21

publication ID 10.5852/ejt.2017.348

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Megaxyela inversa Blank & D.R. Smith

sp. nov.

Megaxyela inversa Blank & D.R. Smith   sp. nov.

Figs 6A–G View Fig. 6 , 11D View Fig. 11 , 12D View Fig. 12


This species is unique by the very long ovipositor sheath with the dorsal outline of valvula 3 straight and the ventral outline convex, and the ovipositor curved dorsally along its longitudinal axis.


The Latin adjective inversus (fem. inversa   ) indicates the shape of the ovipositor, that, in contrast to other Megaxyela   species, is dorsally curved.

Type material


USA: ♀: “USA West Virginia, Randolph Co., Job , 38.8528 N, 79.5293 W, 1-20 April 2012, J. Whitaker 10067, USGS-DRO 292937 ”, [red:] “Holotype Megaxyela inversa   det. S.M. Blank & D.R. Smith 2017 ”, “ DEI-GISHym 32152 ” ( USNM).



UNKNOWN: 1 ♀, “ 4/22/91 ” [supposed collection date: 22. Apr. 1891, no collecting locality given, see insertion in Fig. 6A View Fig. 6 for original labels], DEI-GISHym 22356 (USNM).




COLOR. Black with white pattern, black parts with bronze to blue tinge ( Fig. 6A, C View Fig. 6 ). Head below toruli brown, clypeus and labrum white, preapical region of labrum and mandibles brown white, labial palpomeres 1–2 white ( Fig. 6C View Fig. 6 ). Antenna black with basal ¾ of scape in inner surface light orange. Pronotum and metanotum with bronze tinge, mesonotum and mesepisternum with blue tinge. Tegula basally brown, distally white. Abdominal terga and sterna black, terga 1–8 and sterna with white distal margins, ventral part of terga laterally with 100 µm wide white stripe, sterna 5–7 with 40–50 µm wide lateral white stripe ( Fig. 6A View Fig. 6 ). Valvifer 2 red brown, valvula 3 black except for narrow brown tip, membrane between valvifer 2 and valvula 3 white ( Fig. 11D View Fig. 11 ). Legs orange, procoxa and mesocoxa basally infuscate, distal 0.20 of metafemur, complete metatibia and metatarsus black. Wing subhyaline, venation and pterostigma black ( Fig. 6F–G View Fig. 6 ).

MORPHOLOGY. Body 10.2 mm, fore wing 11.2 mm long. POL: OOL: OCL = 1.0: 1.3: 1.5. Interantennal distance 1.3 × as wide as distance between torulus and eye margin, malar space 0.4 × as wide as interantennal distance. Eye 1.5 × as long as wide, frons at dorsal edge of antennal toruli 1.4 × as wide as maximum diameter of eye. Synantennomere 3 3.1 mm, filament 0.9 mm, with 9 articles. Article 3 of maxillary palp 0.4 μm. Ovipositor sheath 5.1 mm, 3.8 × as long as metatarsomere 1, valvula 3 1.3 × as long as valvifer 2, valvula 3 3.3 × as long as wide. On hind leg, femur 3.1 mm, tibia 4.5 mm, tarsus 3.6 mm, tarsomere 1 5.8 × as long as wide, longer distal spur of tibia 0.3 × as long as tarsomere 1, claws cleft, subapical tooth of claw little smaller at base than apical tooth. Head dull, lateral part of frons rugose, medial part minutely areolate with some 50 µm large pits, vertex and postocellar area mostly minutely areolate to rugulose, gena rugulose ( Fig. 6C View Fig. 6 ). Mesoscutum and mesoscutellum homogeneously minutely areolate. Mesepisternum medially coriarious and shining, with 20 µm large pits. Metatarsomere 1 dorsally and laterally almost glabrous, ventrally densely setose, setae 70–100 µm long ( Fig. 6D View Fig. 6 ). Pulvilli present on metatarsomeres 1–4, on article 1 pulvillus 150 µm long, on article 4 230 µm ( Fig. 6E View Fig. 6 ). Basal and medial sections of valvula 3 of ovipositor sheath straight dorsally, convex ventrally, preapical section almost straight on dorsal and ventral edge, with dense pattern of up to 200 μm long setae ( Figs 6A View Fig. 6 , 11D View Fig. 11 ). Ovipositor 4.6 mm long, weakly curved dorsally, without bulbous areas in middle, without ctenidia ( Fig. 12D View Fig. 12 ). Valvula 1 in distal 0.6 with annuli, basal annuli much more widely spaced then medial and distal annuli, medial annuli very narrowly spaced, subparallel, straight, vertical, ventral edge in distal 0.2 bearing small serrulae. Valvula 2 in distal 0.3 with widely spaced annuli, annuli not extending to ventral edge of valvula, distal 0.3 of dorsal edge of valvula 1 with partly prominent, rounded denticles.




The ovipositor is curved dorsally in Megaxyela inversa   sp. nov. ( Fig. 12D View Fig. 12 ), which is an unusual condition in sawflies and unique in Macroxyelinae   ( Fig. 12A–B, E–H View Fig. 12 ; Smith & Schiff 1998: figs 16–21). The predominant number of sawflies and woodwasps have the ovipositor curved ventrally or the ovipositor is straight (see, e.g., figures in Weltz & Vilhelmsen 2014). Among Xyelidae   , the sheath is curved dorsally to a various degree in species of Pleroneura Konow, 1897   (e.g., Smith et al. 1977; Shinohara 1995, 2016) and in Xyela concava Burdick, 1961   ( Burdick 1961).

Among Nearctic Megaxyela   this species is most similar to M. bicoloripes and M. tricolor   by the slender metatarsus and the red brown metafemur bearing an extensively infuscate apex. It is readily distinguished from all other Megaxyela   species by the outline of the basal and medial portion of valvula 3, which in lateral view is straight dorsally and evenly curved ventrally. The remaining Megaxyela   species have either both the dorsal and the ventral outlines of valvula 3 curved, or the dorsal outline is curved and the ventral straight ( Fig. 11A–C, 11E–H View Fig. 11 ; Smith & Schiff 1998: figs 7–11).

The paratype is presumably from North America because of its discovery in a US collection and the holotype is from West Virginia. Morphometry and figures are from the paratype since the specimen used as holotype was discovered too late to include in this paper.


Smithsonian Institution, National Museum of Natural History