Nematus yokohamensis
Creators: name: Kumar, Deepthi S
name: Sankar, Manimuthu M
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Tenthredinidae
Nematus
Nematus yokohamensis

description: Nematus yokohamensis (Konow, 1895)
Japanese name: Yokohama-higenaga-habachi
(Figs. 6–9)
Holcocneme Yokohamensis [sic] Konow, 1895: 54, 56; Konow, 1905: 62; Enslin, 1910: 316.
Holcocneme yokohamensis: Takeuchi, 1936: 162; Oehlke and Wudowenz, 1984: 420.
Nematus yokohamensis: Takeuchi, 1952: 68; Okutani, 1954: 80; Zinovjev, 1978: 627; Zinovjev, 1979: 430; Abe and Togashi, 1989: 552; Naito et al., 2004: 27; Yoshida, 2006: 54; Sundukov, 2017: 69; Hara and Shinohara, 2018: 106; Hara, 2019: 83; Hara, 2020: 345.
Nematus yokohamensis yokohamensis: Vikberg, 1972: 30.
Nematus (Paranematus) yokohamensis: Taeger et al., 2010: 420; Sundukov and Lelej, 2012: 85.
Redescription, female. Length 7.5–10.5 mm (10.5 mm in lectotype). Black (Fig. 6). Labrum mostly brownish white (Fig. 7G) or brown to dark brown with wide lateral and ventral margins pale brown or brownish white (Fig. 7H). Mandible apically dark reddish brown. Pronotum with posterolateral corner often narrowly brownish (Fig. 6C), rarely yellow. Tegula often yellow or brown laterally. Legs white or pale yellow on apices of coxae, part or most of fore and middle trochanters and trochantelli, hind trochanter and trochantellus, most or wide base of fore tibia, basal third to two thirds of middle tibia, basal third of hind tibia and bases of fore and middle tarsi (Fig. 6A, B, D). Wings nearly colorless transparent, with stigma and veins black; vein C of fore wing sometimes mostly dark yellow (Fig. 6A).
Head in dorsal view narrowing behind eye (Fig. 7A). Postocellar area with anterior furrow shallow and dull, and lateral furrow shallow and sharp. OOL: POL: OOCL 0.8–1.1: 1.0: 0.8–1.0. Frontal area with lateral ridge low or indistinct and anterior ridge well developed and laterally fused with well-developed transverse ridge above dorsal tentorial pit (Fig. 7C). Frontal pit large and deep. Area between dorsal tentorial pit and eye markedly convex (Fig. 7C, E, arrowed). Ridge around torulus dorsolaterally disappearing. Clypeus with width 3.5–4.1×maximum height; maximum height 0.6–0.8×torulus height; ventral edge shallowly or moderately emarginate (Fig. 7G–H); depth of emargination 0.3–1.2× median height of clypeus. Malar space 0.8– 1.0×as long as median ocellus width. Antenna tapering, with length 2.7–2.8×head width (Fig. 6D); first flagellomere length 1.0–1.1×major axis of eye, 4.1–4.8×middle breadth in lateral view (Fig. 7E); second flagellomere 1.0–1.1×as long as first. Mandibles equal in length, each with one small inner notch (Fig. 7H); left one markedly tapering on basal part, very gradually tapering from middle to apex (Fig. 7I), with distinct apical ridge on anterior surface; right one relatively regularly tapering (Fig. 7J), with distinct apical ridge on posterior surface. Mesoscutellar appendage 1.0–1.7×as long as minor axis of cenchrus (Fig. 7K). Mesepisternum with groove along anterior edge dorsally extending to anterodorsal corner; epicnemium with maximum breadth shorter than mesothoracic spiracle height; epicnemial groove distinct and sharp. Katepimeron glabrous except for one to several setae on posterior edge. Hind tibia dorsally rounded, in lateral view 0.8×as broad as hind femur; posterior tibial spur length 1.5–1.8×apical breadth of tibia in lateral view, 0.6×first tarsomere length. Hind tarsus 0.7–0.8×as long as hind tibia (Fig. 6D). Claws with large inner tooth slightly curved inward (Fig. 7L); depth of concavity between teeth longer than distance between teeth. Fore wing with cell Sc 0.4– 0.8×as wide as vein C at middle of base of vein Rs+M. Hind wing with section of vein 1A between cell 1A and crossvein cu-a 1.5–1.8×as long as crossvein cu-a (Fig. 7D).
Hypopygium with posterior edge moderately concave beside median projection. Cercus posteriorly extending slightly before near or slightly beyond ovipositor sheath (Fig. 7M). Ovipositor sheath 0.5–0.6×as long as hind tibia. Valvula 3 in dorsal view tapering on apical part, about as wide as cercus (Fig. 7M), in lateral view narrowly rounded apically (Fig. 7N). Lance annulated on apical two thirds, with distinct subdorsal carina (Fig. 8A); dorsal edge straight in lateral view. Lancet (Fig. 8B–C) with 20–21 serrulae; sclerite before first annulus wide; basal two annuli without ctenidia; annular sutures sinuate, dorsally curved posteriorly, ventrally slightly curved anteriorly.
Body shiny and smooth, with punctures minute or indistinct. Mesopostnotum medially smooth, laterally slightly microsculptured. Metapostnotum smooth. Basal abdominal terga slightly microsculptured.
Male. As in female except for usual sexual differences. Length 6.0– 8.5 mm (Fig. 6E). Legs often pale on apices of fore and middle femora; fore and middle tibiae often entirely pale; fore and middle tarsi often pale except for narrow apices.
Head in dorsal view markedly narrowing behind eye (Fig. 7B). Malar space 0.5–0.7×as long as median ocellus width. Antenna length 2.9–3.1×head width (Fig. 6D); flagellum basally compressed laterally; first flagellomere length 0.8–0.9×major axis of eye and 2.7–2.9×middle breadth in lateral view (Fig. 7F); second flagellomere 1.1–1.2×as long as first.
Procidentia very large, basally slightly constricted, with apical edge truncate or widely rounded in dorsal view (Fig. 7O); tergal hollow laterally ridged. Genitalia (Fig. 8D–E) with parapennis acute apically; harpe with inner edge convex at basal fourth; penis valve (Fig. 8F) with valvispina thorn like, sometimes basally slightly constricted.
Larva. First instar (Fig. 9C): Head and caudal protuberance black; trunk and thoracic legs dark gray. Early instar (Fig. 9D): Black, slightly purplish. Middle instar (Fig. 9E): Head black; trunk dorsally purplish black, laterally and ventrally pale grayish green; thoracic legs with lateral parts of coxae and claws black; surpedal and subspiracular lobes greenish gray. Final instar (Fig. 9F–I): Length about 25 mm; color as in middle instar, but dark markings on lateral region reduced; prolegs on abdominal segments 2–7 and 10; caudal protuberances close to each other; clypeus with two pairs of setae; labrum ventrally deeply incised, medially convex with median furrow, with two pairs of setae (Fig. 9H); antenna flattened, slightly convex apically, with four antennomeres (Fig. 9I); mandible with one or two setae; stipes with one seta; palpifer with one seta.
Cocoon. Length 9.5 mm; blackish brown, double walled (Fig. 9J–K); outer wall netted.
Material examined. Lectotype: $, lYokohamaz lColl. Konowz lHolcocneme Yokohamensis Knw. Japoniaz lNematus wahlbergi Th. f. geogr. yokohamensis Knw. O. Conde det, 1939 Type.z lHOLOTYPUS Nematus y. yokohamensis det. V. Vikberg, 1971 (Konow)z lPR. 308(W)z lDtsch. Ent. Inst. Eberswaldez lGBIF-GISHym 3869z (Fig. 6A–C, 7G, L), deposited in the Senckenberg Deutsches Entomologisches Institut, Müncheberg. Konow (1895) did not designate the holotype. It is not clear whether the specimen he had was only one or more than one. Vikberg (1972) referred to the above specimen as lthe holotypez. We regard this as fixation of the lectotype. Oehlke and Wudowenz (1984) listed this specimen as the holotype.
Other material examined: JAPAN: HOKKAIDO: 1$, Tokachi, Shikaoi, Lake Shikaribetsu-ko, 25. VII. 1939, K. Takeuchi (Fig. 8B). —HONSHU: Tochigi Pref.: 2$1 Ə, 1 cocoon of $ and larval exuvia in it, Nakagawa, Oyamada, coll. larvae on Lonicera japonica, 2. VI. 2020, mat. 12, 14. VI., em. 24, 29. IV. 2021, S. Ibuki (Figs. 6E, 7H–J, 9A–B, D–E, G–K); 1 $, Nakagawa, Wami, 36°46′N 140°10′E, coll. larva on Lonicera japonica, 6. VI. 2020, mat. 10. VI., em. 19. IV. 2021, S. Ibuki (Figs. 6D, 7A, C, E, K, M–N); 1 $, ditto but mat. 12. VI., em. 21. IV2021 (Fig. 8C), and its progeny, 5 Ə, eggs laid 22–23. IV. 2021, larvae hatch. 30. IV., mat. 15. V., em. 22, 24. IV. 2022 (Figs. 7B, D, F, O, 8D–F, 9C, F). — Tokyo Met.: 1$, Nerima, Doshida, 18. V. 1954, Yamamoto; 1 $, Setagaya, Kinuta, 6. V. 1933; 1Ə, Meguro, 5. V. 1928, K. Sato. — Kanagawa Pref.: 1 $, Yokohama, 5. V. 1930, K. Sato; 1 $, ditto but 1. V. 1960; 1 Ə, Yokohama, Shinohara, 3. V. 1953, K. Sato; 2 $, Yokohama, Nishiterao, 5. V. 1955, K. Sato; 2Ə, ditto but 3. V. 1957; 1Ə, Yokohama, Baba, 5. V. 1954, K. Sato; 1 $1 Ə, ditto but 22. IV. 1955; 1 $, Sagamihara, Kobotoke-pass, 18. V. 1957, K. Sato (Fig. 8A). — Toyama Pref: 1 $, Toyama, Omi, 4. VI. 1955, S. Takagi. — Kyoto Pref.: 1 $, Kibune, 6. VI. 1950, Takeuchi; 1 $, Kyoto, 1. V. 1933, Takeuchi. — Osaka Pref: 1 $, Mt. Inunaki-san, 22. V. 1932, Takeuchi (cited by Yoshida, 2006). — Hyogo Pref.: 1 $, Tanba-Sasayama, Lonicera japonica, 10. IV. 1963, T. Okutani. — KYUSHU: Fukuoka Pref.: 1 Ə, Mt. Hiko-san, 18. V. 1963, A. Nakanishi; 1 Ə, Mt. Kora-san, 17. IV. 1962, A. Nakanishi. — Kagoshima Pref.: 1Ə, Cape Sata, 2. V. 1962, A. Nakanishi. — Locality unknown: 1 $, l[Chikusho-tani]z(in Japanese), 25. VII. 1932; 1 $, l[?Kibe]z(in Japanese), 19. V. 1953, J. Yoshioka. — KOREA: 1$, lTonaiz (=Tonae, Ryanggang-do, North Korea), 23. VII. 1935, Takeuchi.
Distribution. Japan: Hokkaido (Hara and Shinohara, 2018), Honshu (Konow, 1895), Sadogashima Is. (Takeuchi, 1936), Kyushu (new record). Korea (Sundukov and Lelej, 2012; Sundukov, 2017; this study); Russia (Sakhalin, Russian Far East, Siberia), China (Sundukov and Lelej, 2012; Sundukov, 2017).
Although Sundukov and Lelej (2012) and Sundukov (2017) listed Korea in the distribution of this species, the reason or original source is unknown. Lee et al. (2019) did not include this species in the Korean fauna. We examined one female of this species from North Korea (see material examined). The records from China may need confirmation, because Wei et al. (2006) regarded the record from China (Kang, 1992) as being based on misidentification. Sundukov and Lelej (2012) included Finland in the distribution and it was followed by Hara and Shinohara (2018). However, Sundukov (2017) excluded Finland from the distribution. Sundukov and Lelej`s distribution list seems to include the distributions of N. wahlbergi tavastiensis Vikberg, 1972, described from Finland and N. tulunensis Vikberg, 1972, described from Siberia, both originally regarded as the subspecies of N. yokohamensis. There is no record of N. yokohamensis from Finland.
Host plants. Caprifoliaceae: Lonicera japonica Thunb. (new record), L. spp. (Sundukov, 2017).
Life history. In the lowlands of Honshu, adults were collected from late April to early June and larvae in early June. The larvae collected in early June matured in middle June and became adults in the following spring under rearing conditions. This sawfly has one generation per year. Under rearing conditions, a female inserted her eggs singly into leaves beside or at the main or lateral veins (Fig. 9A–C). Larvae solitarily fed on leaves. No extra molt was observed when the larvae reached maturity. Cocoons were made between papers or in the soil in captivity.
Remarks. The original description of this species by Konow (1895), containing only the female, is very simple. Takeuchi (1936) briefly described the male as lUndescribed male agrees very well with the female except the most of four anterior tibiae and their tarsi white. Length of male 7 mm.z, based on one male. Vikberg (1972) gave the key characters with an excellent figure of the lancet of the lholotypez, but he examined only the lholotypez. We here redescribe this species based on a good series of specimens listed above, considering the variation and the characters previously not mentioned.
This species is distinguished from other Japanese nematines in having the frons with an anterior ridge well developed and laterally extending into a facial orbit (Fig. 7C–D) and this part of a facial orbit markedly convex (Fig. 7C–F, arrowed). In the key to the species of the Nematus lonicerae and N. wahlbergi groups by Vikberg (1972), part of our female specimens of N. yokohamensis do not fit l N. yokohamensis yokohamensis z (= N. yokohamensis) but they may go to l N. yokohamensis tavastiensis z (= N. wahlbergi tavastiensis Vikberg, 1972), because key characters for N. yokohamensis, the color of pronotum and fore-wing vein C and the narrowness of stigma, are variable in our material. However, our female specimens of N. yokohamensis have the fore and middle tarsi always strongly infuscate (Fig. 6D) (not infuscate in N. wahlbergi tavastiensis; Vikberg, 1972) and the second annulus of the lancet without ctenidial teeth (Fig. 8B–C; fig. 13 in Vikberg, 1972) (with well-developed ctenidial teeth in N. wahlbergi tavastiensis; fig. 15 in Vikberg, 1972). In the key to species of Nematus (Paranematus) Zinovjev, 1978 (=the N. wahlbergi group) by Zinovjev (1978, 1979), N. yokohamensis goes to the couplet 2–3 consisting of N. tulunensis Vikberg, 1972 and l N. wahlbergi Thomson, 1871 z (= N. wahlbergi wahlbergi), but differs from N. tulunensis in having the pronotum with the posterolateral corner not pale or narrowly brown or yellow (very broadly yellow in N. tulunensis; Vikberg, 1972), the median fovea rounded (Fig. 7C) (oblong, appearing as a deep groove in N. tulunensis) and the lancet slightly upturned apically and its second annulus without ctenidial teeth (Fig. 8B–C) (distinctly upturned and its second annulus with well-developed ctenidial teeth in N. tulunensis; fig. 14 in Vikberg, 1972 and figs. 7, 17 in Zinovjev, 1978). Nematus yokohamensis differs from N. wahlbergi wahlbergi in having the legs mostly black (Fig. 6B, D) (mostly yellow to reddish yellow in N. wahlbergi wahlbergi; fig. 43 in Prous et al., 2019), the flagellomere 1 slightly curved with the length 4.1– 4.8×the middle breadth in lateral view (Fig. 7E) (straight with the length 3.2–4.0×the middle width in N. wahlbergi wahlbergi; fig. 2 in Zinovjev, 1978, 1979) and the second annulus of the lancet without ctenidial teeth (Fig. 8B–C; fig. 13, lectotype, in Vikberg, 1972) (with well-developed ctenidial teeth in N. wahlbergi wahlbergi; fig. 16 in Vikberg, 1972 and fig. 10 in Zinovjev, 1978). Males are known only for N. yokohamensis and N. wahlbergi wahlbergi in the N. wahlbergi group. They are easily distinguished by the color of legs: Mostly black in N. yokohamensis (Fig. 6D); mostly yellow to reddish yellow in N. wahlbergi wahlbergi (Enslin, 1915; Prous et al., 2019). However, their penis valves are not distinctly different (compare Fig. 8F with fig. 50 in Prous et al., 2019).
description: Published as part of Kumar, Deepthi S & Sankar, Manimuthu M, 2023, Taxonomic Notes and New Distribution and Host Plant Records for Sawflies and Woodwasps (Hymenoptera, Symphyta) of Japan VIII, pp. 57-74 in Bulletin of the National Museum of Nature and Science. Series A, Zoology 49 (2) on pages 62-67, DOI: 10.50826/bnmnszool.49.2_57, http://zenodo.org/record/13826588