Euura imperfecta ( Zaddach, 1876 )

Fu, Yuanzun, Yuan, Yuan, Shen, Qian, Xu, Hao, Ye, Zheng, Guo, Li, Wu, Xiaoliang & Zhao, Yunhe, 2021, Taxonomic Notes and New Distribution and Host Plant Records for Sawflies and Woodwasps (Hymenoptera, Symphyta) of Japan VI, Bulletin of the National Museum of Nature and Science. Series A, Zoology 47 (4), pp. 163-188 : 169-177

Euura imperfecta ( Zaddach, 1876)

Japanese name: Karamatsu-madara-habachi ( Figs. 3A–G, L–O , 4A–N , 5A–P , 6A–C , 7A–D )

Nematus imperfectus Zaddach, 1876: 80 .

Pachynematus imperfectus : Jörgensen, 1906: 350; Benson, 1958: 233; Ito, 1959; Pschorn-Walcher and Eichhorn, 1963: 62; Verzhutskii, 1966: 138; Verzhutskii, 1981: 210.

Pachynematus? imperfectus : Takizawa, 1957: 27.

[Unidentified species 2]: Hara and Kitagawa, 1986: 21.

Nematus (Larinematus) imperfectus : Zhelochovtsev and Zinovjev, 1988: 169.

Pikonema imperfectum : Zinovjev, 1993: 21.

Larinematus imperfectus : Lacourt, 1999: 151; Lacourt, 2020: 428.

Pachynematus (Larinematus) imperfectus : Taeger et al., 2010: 438; Macek et al., 2020: 532.

Euura imperfecta : Prous et al., 2014: 46; Shinohara and Hara, 2015: 174; Hara, 2019: 73; Hara, 2020: 89, 349.

For more references, see Lacourt (1999).

Redescription (female and male). Length 5.5– 6.5 mm in female, 5.5 mm in male. Female yellow, red yellow or brown and black ( Fig. 3A–B, E–G ); head capsule with peculiar black markings ( Fig. 4A–D, L–N ); antenna black; thorax partly black; mesepisternum black on epicnemium and often ventrally or ventrolaterally ( Fig. 4B, F–G ); legs with coxae basally black and tarsi and apex of hind tibia sometimes slightly darkened; abdomen dorsally or mostly black; valvula 3 always black. Male mostly black ( Fig. 3C–D ); legs yellow from apices of femora to tarsi but tibiae and tarsi slightly darkened apically; subgenital plate yellow. In both sexes, wings very slightly yellowish ( Fig. 3A, F, C ); stigma almost uniformly pale brown to brown, sometimes basally pale; veins mostly brown to black; vein C mostly or basally yellow.

Head in dorsal view with length behind eye 0.6–0.8 × eye length in female, 0.4–0.5 × in male ( Fig. 4A, H, L ); length behind lateral ocellus 2.0–2.8 × length of lateral ocellus in female, 1.7–1.8 × in male. Frontal area with lateral and anterior ridges usually distinct ( Fig. 4B, I, M ); anterior ridge not grooved medially. Distance between eyes at torulus 1.4–1.5 × eye height in female, 1.2 × in male ( Fig. 4C, J, N ). Area just above torulus almost flat and triangular, laterally with long straight furrow ( Fig. 4E ). Dorsal tento- rial pit obscure. Narrow ridge around torulus dorsally widely vague or disappearing. Paraantennal field normal, covered with setae except for narrow medial margin. Clypeus distinctly concave roundly on ventral margin ( Fig. 4C, J, N ); depth of ventral emargination 0.3–0.7 × median height of clypeus; clypeus with width 3.3–3.9 × maximum height; maximum height 0.7–0.9 × torulus height. Malar space length 1.2–1.4 × median ocellus width in female, 0.8–0.9 × in male. Antenna length 2.1–2.5 × head width in female, 3.0 × in male ( Fig. 3A, C, E ); flagellomere 1 0.8–0.9 × as long as major axis of eye, simple in female, slightly convex basally on ventral margin in lateral view in male ( Fig. 4K ); flagellomere 2 1.1–1.3 × as long as flagellomere 1. Left mandible 1.1–1.2 × as long as right one, and in outer view sharply tapering basally, thin from middle to apex, with middle part same thickness or slightly thickening towards apex ( Fig. 4F ). Right mandible rather sharply tapering on basal half and gradually tapering on apical half ( Fig. 4G ). Basal outer surfaces of both mandibles not widely flattened or concave. Maxillary palpus rather short, with palpomere 2 0.7–0.8 × as long as palpomere 3 and palpomere 6 0.7–0.8 × as long as torulus height.

Mesoscutellar appendage with length 0.9– 1.6 × minor axis of cenchrus ( Fig. 5A, I ). Metascutellum length 0.9–1.3 × minor axis of cenchrus. Mesepisternum with groove along anterior edge extending into epicnemium. Epicnemium with ventral edge distinctly grooved. Katepimeron entirely glabrous. Anterior fore tibial spur with velum. Hind tibia normal, 0.8 × as broad as hind femur in anterior view; posterior hind tibial spur 0.9–1.2 × as long as apical breadth of hind tibia, 0.4–0.5 × as long as hind tarsomere 1. Hind tarsus 0.8–1.0 × as long as hind tibia. Tarsal claws narrow, with small inner tooth ( Fig. 5B, J, L ); depth of concavity between apical and inner teeth 0.3–0.5 × distance between these teeth. Fore wing with cell Sc 0.2–0.6 × as wide as vein C at level of base of vein Rs+M ( Fig. 5C ). Hind wing with section of vein 1A between cell 1A and crossvein cu-a 1.9–2.1 × as long as crossvein cu-a.

In female abdomen, sternum 7 with posterior margin deeply concave beside median projection ( Fig. 5D ). Tergum 9 normal in size, in lateral view 0.8–1.6 × as long as tergum 8 at level of spiracle 8 ( Fig. 5E, M ). Cercus 3.0–5.0 × as long as wide, posteriorly extending to or slightly beyond apex of valvula 3 ( Fig. 5E, G, M, O ). Ovipositor sheath 0.3 × as long as abdomen ( Fig. 3B, G ), 0.6–0.7 × as long as hind tibia; valvula 3 in lateral view with apical edge nearly truncate or widely rounded ( Fig. 4E, M ); both valvulae 3 combined apically slightly or distinctly concave, with apicolateral ridge sharp ( Fig. 5F–G, M–P ). Lance in lateral view with dorsal margin slightly concave ( Fig. 6A ); radix with subdorsal carina; annuli distinctly oblique. Lancet with radix 1.2– 1.3 × as long as lamnium ( Fig. 6B, C ); lamnium with 14–15 annuli; annuli arched; ctenidial setae absent on ventrobasal and dorsoapical parts of lamnium; annulus 1 usually without ctenidial setae; ctenidial setae about as long as length of annulus; ventral margin of lamnium not serrate, without distinct denticles.

In male abdomen, procidentia with sharply defined median area ( Fig. 5K ); tergal hollow with anterior edge distinctly ridged laterally. Subgenital plate 0.4–0.5 × as long as abdomen, 0.7–0.8 × as long as hind tibia ( Fig. 3D ), gradually tapering and narrowly rounded apically ( Fig. 5K ). Genitalia with harpe in ventral view about as long as wide ( Fig. 7A ); parapennis apically pointed; penis valve with paravalva apically protruding below valvispina ( Fig. 7B–D ); valvispina narrow and acute.

Head capsule mostly distinctly or slightly microsculptured and inconspicuously punctured; clypeus not microsculptured. Thorax predomi- nantly microsculptured; medial part of mesopostnotum, whole metapostnotum, etc. not microsculptured; punctures generally inconspicuous; mesoscutum, propleuron and ventrolateral part of mesepisternum with small punctures. Abdomen microsculptured; sterna slightly or inconspicuously microsculptured.

Immature stages. Egg long oval ( Fig. 3 L ). Semifinal instar larva ( Fig. 3M ): head and legs pale yellow brown; legs basally narrowly black; trunk pale green, with slightly blackish subdorsal stripe. Final instar larva ( Fig. 3N–O ): 15 mm long, as in semifinal larva, but trunk with distinct blackish green subdorsal stripe and narrow dark green pleural stripe. Cocoon: 8 mm long, brown, double walled; outer wall thin. For more information, see Jörgensen (1906), Verzhutskii (1966) and Macek et al. (2020).

Material examined. HOKKAIDO: 1˂ ( Fig. 6A ), Shintoku, Shintoku, 8. V. 2012, H. Hara (cited by Hara, 2020); 1 ˂ ( Figs. 5B , 6B ), Bibai, 9. V. 1961, K. Kamijo; 1˂, same locality, 7. V. 1987, H. Hara; 1 ˂ ( Figs. 5I , 7A, C–D ), same data but 3. V. 1988; 1 ˁ, same data but 6. V. 1988; 1 ˂, same data but 8. V. 1988; 1 ˁ ( Figs. 3C–D , 4H–K , 5J–K , 7B ), Hayakita, 13. V. 1986, H. Hara; 1˂, same data but 11. V. 1987; 1˂ ( Fig. 5D ), same locality, coll. cocoon in litter under Larix kaempferi , 30. IV. 1987, em. 25. V. 1987, H. Hara; 1 ˂, same locality but 19. V. 1987, H. Hara; 1 ˂ ( Figs. 4D, F–G , 5A, C ), same data but 6. V. 1988; 3˂ ( Figs. 3A–B , 4A–C, E , 5E–H ), same locality, coll. litter under Larix kaempferi , em. 28, 30. IV. 1992, H. Hara, and their progeny ( Fig. 3 L ). — HONSHU: Nagano Pref.: 3˂, Ueda, Sanada-machi, Soehi, 30. IV. 1956, Takeuchi (probably reared); 1 ˂, Aoki-toge, coll. larva on Larix kaempferi 1956, em. 19. III. 1957, Ito (cited by Ito, 1959).

Distribution. Japan: Hokkaido ( Shinohara and Hara, 2015), Honshu ( Takizawa, 1957; Ito, 1959). Russia: European part, Siberia ( Verzhutskii, 1981; Zhelochovtsev and Zinovjev, 1988). Europe ( Zaddach, 1876; Benson, 1958; Taeger et al., 2018).

Host plants. Pinaceae : Larix decidua Mill. ( Jörgensen, 1906), L. kaempferi (Lamb.) Carrière ( Takizawa, 1957; Ito, 1959), L. sibirica Ledeb. ( Verzhutskii, 1966, as lлиственницы сибирскойz).

Life history. In our observation in Hokkaido, Japan, this sawfly has one generation a year; the adults were collected in May; under rearing con- dition, the female laid her eggs singly on needles ( Fig. 3 L ); the cocoons were found within the litter in larch forests. For more information, see Jörgensen (1906), Pschorn-Walcher and Eichhorn (1963), Verzhutskii (1966) and Macek et al. (2020).

Remarks. Euura imperfecta is mainly characterized by the following features: area just above torulus almost flat and triangular and laterally with long straight furrow ( Fig. 4E ); female sternum 7 with posterior margin deeply concave beside median projection ( Fig. 5D ); male procidentia with median area sharply defined ( Fig. 5K ). The following character states are also useful to distinguish this species from other congeners of Euura and similar genera: tarsal claws with small inner tooth ( Fig. 5B, J, L ) and depth between apical and inner teeth about half or less of distance between apices of these teeth; narrow ridge around torulus widely vague or disappearing dorsally ( Fig. 4E ); mandibles asymmetrical, in outer view left mandible with middle part same thickness or slightly thickening towards apex ( Fig. 3F ), right mandible continuously tapering from base to apex ( Fig. 4G ); katepimeron entirely glabrous; in female, valvulae 3 not tapering and apically concave ( Fig. 5F–H, N–P ); in lancet, lamnium without serrulae and denticles on ventral margin; in male, tergal hollow of tergum 8 with anterior edge distinctly ridged laterally ( Fig. 5K ).

Zhelochovtsev in Zhelochovtsev and Zinovjev (1988) established Larinematus Zhelochovtsev, 1988 as a subgenus of Nematus Panzer, 1801 for three species, E. imperfecta ( Fig. 3A–D ), E. itoi ( Fig. 3H–K ) and one unstated species. Zinovjev (1993) considered this subgenus a species group of Pikonema Ross, 1937 . Lacourt (1999, 2020) raised Larinematus to the rank of genus. Roller and Haris (2008) described a new species under l Pachynematus (Larinematus) z. Taeger et al. (2010) and Macek et al. (2020) treated Larinematus as a subgenus of Pachynematus Konow, 1890 . On the other hand, Prous et al. (2014) syn- onymized Larinematus , Pachynematus and Pikonema with Euura Newman, 1837 . Actually, the features of Larinematus stated by previous authors are not stable or difficult to recognize, judging from Japanese specimens of these two species. Zhelochovtsev and Zinovjev (1988), Zinovjev (1993), Macek et al. (2020) and Lacourt (2020) distinguished Larinematus or the E. imperfecta group from other species of former Pachynematus mainly by the relative lengths of hind tibia and tarsus and the shape of the ovipositor sheath. Zhelochovtsev and Zinovjev (1988), Macek et al. (2020) and Lacourt (2020) stated that Larinematus has the hind tarsus as long as or longer than the hind tibia. Benson (1958) also characterized E. imperfecta by a long hind tarsus. However, in the Japanese specimens of the two species, the hind tarsus is often distinctly shorter than the hind tibia in E. imperfecta ( Fig. 3B ) and always so in E. itoi ( Fig. 3I ) (the ratio is 0.83– 0.97: 1.0 in E. imperfecta and 0.78–0.86:1.0 in E. itoi ). Zhelochovtsev and Zinovjev (1988) stated that the ovipositor sheath of Larinematus was with lопорной плоЩадкойz (probably refers to a wide concavity at the apex; Fig. 5F, N ) with a figure of the ovipositor sheath of E. imperfecta . Macek et al. (2020) also adopted this feature for Pachynematus (Larinematus) . However, in Euura itoi , the apex of the ovipositor sheath is mostly flattened, dorsally narrowly elevated and with a median carina ( Fig. 5V, X ). Lacourt (2020) wrote that the ovipositor sheath was incised when viewed from above as a generic feature of Larinematus . The sheaths combined are apically incised in dorsal view in E. imperfecta ( Fig. 5G, O ) but truncate in E. itoi ( Fig. 5W ). It is impossible to separate Larinematus or the E. imperfecta group from other species of former Pachynematus except for the host plant. Furthermore, there are some significant differences between these two species apart from their morphological differences. The antenna of E. imperfecta shows distinct sexual difference. The male antenna is longer than that of the female ( Fig. 3A, C ), and the male flagellomere 1 is basally convex on the ventral margin ( Fig. 4K ) while the female flagellomere 1 is simple. On the other hand, there is no distinct structural difference between the female and male antennae of E. itoi . The life cycle of E. imperfecta is univoltine while that of E. itoi is multivoltine. These two species do not appear to be closely related.

Apart from the relative lengths of hind tibia and tarsus, Japanese specimens of E. imperfecta well agree with the concept of this species by Benson (1958). He wrote lUnderthorax with at least mesosternum blackz. In the Japanese specimens, the mesepisternum is often not darkened ventrally. The Japanese specimens also well agree with the description by Muche (1974) except for the color of the stigma. He wrote lStigma braun mit breiter weisser Basisz, but the Japanese specimens have the uniformly brown stigma ( Fig. 3A, C, E ).

The Hokkaido larva agrees with the description of the European larva by Jörgensen (1906). The trunks of these mature larvae are green with two dark longitudinal stripes (subdorsal and pleural stripes) ( Fig. 3N–O; p . 533-fig. 3 in Macek et al., 2020). However, according to Verzhutskii (1966), the Siberian larva has the trunk with only one dark longitudinal stripe (subdorsal stripe) and the ventral side is distinctly paler than the dorsal side (Рис. 34-8 and Рис. 43 in Verzhutskii, 1966). Furthermore, the Honshu larva quite dif- fers from the Hokkaido, European and Siberian larvae. According to Ito (1959), the Honshu larva is wholly purplish black in the semifinal instar and younger larvae and has the head blackish brown and the trunk dark brown with a pale brown middorsal line in the final instar larva. Therefore, Ito (1959) questioned identifying the Honshu specimens with E. imperfecta and stated the identification was tentative. We have not found any difference between the Hokkaido and Honshu adults and so consider them conspecific. More material and genetical study will be needed to interpret the large larval color variation.

Figures

Fig. 3. A–G, L–O, Euura imperfecta: A–B, female, Hokkaido, dorsal and ventral views; C–D, male, Hokkaido, dorsal and ventrolateral views; E–F, female, Honshu, dorsal and ventrolateral views; G, female, Honshu, ven- trolateral view; L, egg, Hokkaido; M, semifinal instar larva, lateral view; N–O, final instar larva, lateral and dorsal views; M–O, Hokkaido, Bibai, 1986. H–K, Euura itoi: H–I, female, dorsal and ventrolateral views; J–K, male, dorsal and ventrolateral views.All photographed by Hara.

Fig. 4. A–N, Euura imperfecta: A–G, female, Hokkaido; H–K, male, Hokkaido; L–N, female, Honshu. O–X, Euura itoi: O–U, female; V–X, male. A, H, L, O, V, Head, dorsal view; B, I, M, P, W, dorsomedial part of head anterodorsal view; C, J, N, Q, X, head, anterior view; D, K, R, Y, head, lateral view; E, S, torulus and its surroundings, anterolateral view; F, T, left mandible, outer view; G, U, right mandible, outer view. All photo- graphed by Hara.

Fig. 5. A–P, Euura imperfecta: A–H, female, Hokkaido; I–K, male, Hokkaido; L–P, female, Honshu. Q–AA, Euura itoi: Q–X, female; Y–AA, male.A, I, Q, Y, Posteromedial part of thorax, dorsal view; B, J, L, R, Z, tar- sal claw, anterior or posterior view; C, S, anteromedial part of fore wing; D, T, apical part of abdomen, ventro- lateral view; E, M, U, abdomen apex, lateral view; F, N, V, ditto, posterolateral view; G, O, W, ditto, dorsal view; H, P, X, ditto, posterior view; K, AA, apical part of abdomen, dorsal view. M–N, P, Ovipositor removed; K, genitalia removed.All photographed by Hara.

Fig. 6. Female ovipositor. A–C, Euura imperfecta: A–B, Hokkaido; C, Honshu. D–E, Euura itoi. A, D, Ovipositor; B–C, E, lancet.All photographed by Hara.

Fig. 7. Male genitalia. A–D, Euura imperfecta, Hokkaido; E–I, E. itoi. A, E–F, Genital capsule: A, ventral view (penis valve removed); E, F, dorsal and ventral views. B–D, G–I, Penis valve, lateral view (left dorsal). All photographed by Hara.