Neurotoma atrata Takeuchi, 1930

Bourke, Joanna, 2024, Taxonomic Notes and New Distribution and Host Plant Records for Sawflies and Woodwasps (Hymenoptera, Symphyta) of Japan IX, Bulletin of the National Museum of Nature and Science. Series A, Zoology 50 (1), pp. 19-32 : 20-22

Neurotoma atrata Takeuchi, 1930

Japanese name: Kuro-hirata-habachi

( Fig. 1 )

Neurotoma atrata Takeuchi, 1930: 8 ; Shinohara, 1980: 91; Taeger et al., 2010: 82; Shinohara, 2019: 6; Shinohara, 2020: 8, 232; Shinohara et al., 2022: 58 .

Neurotoma harai Shinohara, 1993: 126 ; Shinohara, 1997: 70; Shinohara, 2002a: 418; Katayama, 2004: 48; Shinohara and Yamada, 2005: 53; Shinohara and Hara, 2005: 273; Shinohara et al., 2007: 68; Taeger et al., 2010: 82; Shinohara, 2019: 6; Shinohara, 2020: 8, 232; Anonymous, 2023. N. Syn.

For more references, see Shinohara et al. (2022).

Material examined. HONSHU: Tochigi Pref.: 1 ♂, Nakagawa, Bato, 36°47'N 140°10'E, coll. larva on Quercus serrata , 30. IV. 2018, mat. 7. V., em. 27. III. 2019, S. Ibuki ; 1♂, same data except em. 5. IV. 2019. Tokyo Met.: 1♀, Hodokubo, Hino-shi, Tokyo, 16. IV. 2003, H. Takahashi .

Larva. Middle instar ( Fig. 1C–E ): Head black with frontal surface creamy white; mandible and antenna mostly black; trunk slightly greenish creamy white, dorsal midline darker and lateral margins and ventral midline whitish; lateral and dorsal prothoracic shields marked with black; cervical sclerite, thoracic legs and subanal appendage black; last abdominal sternum narrowly blackish. Late instar ( Fig. 1F–H ): Head pale brown with frontal surface pale olive and lateral surface marked with dark brown; mandible and antenna mostly dark brown; trunk sordid greenish white, dorsal midline darker; lateral prothoracic shield and cervical sclerite marked with black; thoracic legs and subanal appendage whitish. Mature larva ( Fig. 1I, J ): Head, including mandible and antenna, olive; trunk, thoracic legs and subanal appendage vivid pale green; lateral prothoracic shield and cervical sclerite marked with black.

Distribution. Japan (Hokkaido, Honshu), Russia (Primorskij kraj), Korea and China (Zhejiang province).

Host plant. Fagaceae : Quercus acutissima Carruth. ( Shinohara, 1980), Q. crispula Blume var. crispula ( Shinohara, 1993) , Q. serrata Murray (new record).

Field observations and rearing records. On April 30, 2018, Ibuki found a nest of gregarious pamphiliid larvae on a small tree of Q. serrata in Nakagawa Town, Tochigi Prefecture. The nest was located at the apex of a branch near the top of the tree and contained three middle instar larvae. The nest was originally made of one young leaf loosely folded below with silk. After rearing in a container for a few days, adjacent leaves were added to form a partly web nest ( Fig. 1A ). On the midvein on the undersurface of the original nest leaf, remains of two eggshells were found ( Fig. 1B ). The two eggshells were found far apart and another eggshell was probably present on the halfway between them, suggesting that the eggs were laid on the midvein in a row with some space between them but not in a compact group. On May 2, the larvae probably molted because the head color changed from black to pale brown ( Fig. 1F, G ). On May 3, one of the three larvae died. On May 7, two larvae matured ( Fig. 1 I, J ) and soon entered the soil. One male each emerged on March 27 and April 5, 2019.

On May 8, 2019, a larval nest was found on Q. serrata in Kitazawa, Wami, with only one late-instar larva inside. Weather the larva was originally solitary or gregarious was not confirmed. To check if the larva also feeds on Q. acutissima , only the leaves of Q. acutissima were given to the larva on May 9 and thereafter. The larva fed on Q. acutissima without apparent problems and matured on May 14. No adult emerged in the following year.

On May 13, 2019, a gregarious larval nest, containing four larvae, was found on Q. acutissima in Wami. Three larvae matured on May 21 and one larva matured on May 22. Three parasitoid wasps emerged on April 17 to 21, 2020.

Variation of the adults. The two male adults obtained by rearing in this work lived in larval stage in the same nest and therefore are doubtless offsprings of the same female. They are about the same size and quite similar in structure but differ in coloration. One of them (emerged on March 27) has the head and hind femur (except for the trochantellus) entirely black and the pale areas on the mandibles and legs distinctly greenish, whereas the other specimen (emerged on April 5) has the clypeus and the hind femur (on apical dorsal surface) marked with creamy white. The former is more similar to the only previously known male ( Shinohara, 1980; Shinohara et al., 2022, fig. 20), though the latter old specimen collected in 1960 has no distinct greenish tint on the mandible and legs and the antennal scape largely marked with creamy white ventrally. Therefore, the coloration of the clypeus, antennal scape and hind femur in the three known male specimens are not quite stable.

Remarks. Neurotoma atrata was described from two females collected in Gifu Prefecture, Honshu, Japan ( Takeuchi, 1930). Shinohara (1980) examined nine females (one specimen from Mabashi was wrongly cited as a male) and one male from Honshu, Japan, and four females from Korea. Two females, one each from Japan and Korea, were reared specimens and the host was lKunugiz (= Q. acutissima ). This species was later recorded from Primorskij kraj, Russia, based on one female and one male specimens by Shinohara (1992). Shinohara (1993) described N. harai based on two female and one male specimens, all of them, except one female, reared from larvae feeding on l Quercus mongolica var. grosseserrata z in Hokkaido. Shinohara (1993) distinguished N. atrata and N. harai by the different color patterns of the frons, antennal scape and legs, host plants and distribution.

Since 1993, two females and one male of l N. harai z have become available from Japan (Shinohara, 1997; Katayama, 2004; Anonymous, 2023) and here we add one female and two reared males of l N. atrata z with a new host plant record of Q. serrata . From Korea and China, collection records of three females were added (Shinohara and Lee, 1997; Shinohara and Xiao, 2006; Shinohara and Tripotin, 2021).

After a close examination of all currently available information, we conclude that all the specimens previously identified as N. atrata and N. harai belong to the same species and the two names are synonymous ( Neurotoma harai Shinohara, 1980= Neurotoma atrata Takeuchi, 1930 , new synonym). The addition of the new material, though small in number, has shown that the distinguishing characters used to separate N. atrata and N. harai by Shinohara (1993) are variable as discussed above. Neurotoma atrata , thus newly defined, is distributed in Japan (Hokkaido, Honshu), Russia (Primorskij kraj), Korea and China (Zhejiang province) and the larvae feed on Q. acutissima , Q. crispula var. crispula and Q. serrata .

The larva of N. atrata is distinguished from that of N. mandibularis , feeding on Quercus robur L. ( Green, 2023), by the pale brown or olive head and the lack of black areas on the dorsal prothoracic shield in the late feeding instar and after maturation ( Fig. 1F–J ). The larva feeding on lSangsurinamuz (= Q. acutissima ) determined as l Caliroa oishii (Takeuchi) z (Tenthredinidae) by Lee and Chung (1997) is probably N. coreana , because the photograph of the adult on the same page is probably this species. This larva is similar to that of N. atrata but differs from it in having the head and the lateral prothoracic shield nearly concolorous to the trunk. An undetermined pamphiliid larva on Q. mongolica photographed in Korea by Sohn (2006) is very similar to the middle instar larva of N. atrata ( Fig. 1C–E ), though the last abdominal sternum of this Korean specimen has no blackish spot. This Korean larva may possibly belong to N. atrata , and in this case Q. mongolica is also a host plant of N. atrata .

Figures

Fig. 1.ɹNeurotoma atrata on Q. serrata, photographed in Nakagawa by S. Ibuki in 2018 and 2019. — A, Nest containing three larvae, seen from above, May 3, 2018 (deformed after three days of rearing in a container); B, inside of nest, seen from below, remains of two egg shells arrowed, April 30, 2018; C–E, middle instar larva, April 30, 2018 (C, E) and May 8, 2019 (D); F–H, late instar larva, May 2 (F), May 3 (G) and May 4, 2018 (H); I, J, mature larva, May 7, 2018.