Fagineura Vikberg & Zinovjev 2000
Creators: name: Hara, Hideho
name: Ibuki, Shinichi
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Tenthredinidae
Fagineura

description: Fagineura Vikberg & Zinovjev, 2000
Fagineura Vikberg & Zinovjev, 2000 (in Shinohara et al. 2000): 114; Togashi 2006: 169; Taeger et al. 2010: 405; Prous et al. 2014: 18, 26, 47; Liu et al. 2019: 32; Hara 2019: 77; Hara 2020: 338; Liu et al. 2021: 126.
Type species: Fagineura crenativora Vikberg & Zinovjev, 2000, by original designation.
Diagnostic characters. Outer margin of eye without distinct furrow (Figs 6A–N). Inter-antennal area protruded anteriorly beyond anterior ridge of frontal area (Figs 6A–N). Torulus completely surrounded by narrow ridge (Fig. 6O). Paraantennal field covered with setae except for narrow medial part (Figs 6P–S). Malar space length 0.2–0.8 × median ocellus width. Labrum apically rounded (Figs 7B, C). Left and right mandibles equal in length (Figs 7A–C); basal outer surface not widely flattened or concave (Figs 7D–O). Maxillary palpus not shortened (Fig. 7A); palpomere 2 length 0.7 × palpomere 3 length; palpomere 6 length 1.1–1.2 × torulus height.
Notaulus distinct (Figs 8A–E). Mesoscutellar appendage 0.9–1.5 × as long as minor axis of cenchrus. Median membranous part of mesopostnotum not or slightly widened anteriorly. Mesepisternum smooth between punctures, with distinct groove along anterior edge (Fig. 8F); this groove dorsally extending into epicnemium. Anterior fore tibial spur with distinct velum; hind leg normal; hind tarsomere 1 not grooved on anterior and posterior surfaces; tarsal claws without basal lobe, with inner tooth long and slightly curved (Figs 8O–V); inner tooth as long as or somewhat shorter than apical tooth; depth of concavity between apical and inner teeth longer than distance between their apices. In fore wing, posterior end of transverse section of vein Sc situated before or at joint of vein M and vein R (Figs 8W–Y); vein R+M longer than first section of vein Rs (Fig. 8X); joint of crossvein 2r-m with vein M located apical to joint of crossvein 2m-cu with vein M (Figs 1B, etc.); basal section of vein 2A+3A straight and apically separated from vein 1A. In hind wing, vein 2A complete and cell 1A closed; section of vein 1A between cell 1A and crossvein cu-a 0.7–1.7 × as long as crossvein cu-a.
In female abdomen, tergum 9 normal size (Figs 1D, etc.); its visible length 0.7–2.0 × visible length of tergum 8 at level of spiracle 8. In male abdomen, tergum 8 with tergal hollow with distinct anterior edge (Figs 14A–C). Penis valve with pseudoceps and paravalva divided (Figs 14K–P); paravalva expanded.
Character assessment. We here comment on several characters adopted by previous authors for Fagineura.
- Postocellar area length. Liu et al. (2019, 2021) stated “postocellar area more than 2.0 × as wide as long” under the diagnosis of Fagineura. In our material, the ratio is more than 2.0 × in the F. crenativora group (Figs 6A–E) but sometimes 2.0 × or less in the F. quercivora group (Figs 6H, L) (for the species groups, see under Remarks below).
- Malar space length. Liu et al. (2019, 2021) stated “malar space shorter than diameter of median ocellus, and in most species not exceeding 0.5 × of diameter of median ocellus” under the diagnosis of Fagineura. According to them, the ratios of four Chinese species are 0.3–0.8 ×. In the other seven species of the genus, the malar space is 0.2–0.8 × as long as the median ocellus width (= horizontal diameter). We also consider the short malar space to be a good generic character of Fagineura. Prous et al. (2014) erroneously treated Fagineura as one of the genera with “Malar space 1.0–2.0 times as long as diameter of front ocellus” in the key to Nematinae genera (pp. 22–26, from the lower half of the couplet 18 to the couplet 22). We suggest some modification of the key under Remarks below so that Fagineura can be identified.
- Shape of mandibles. Vikberg & Zinovjev (in Shinohara et al. 2000) established Fagineura for a single species, F. crenativora. One of the generic characters they stated is “Mandibles symmetric, rather narrow, gradually tapering from base to apex, without carina in apical half”. More precisely, each of the mandibles of F. crenativora tapers rather sharply on the basal half and gradually on the apical half in the outer view (Figs 7A, D, J) and has a low and dull apical carina on both anterior and posterior surfaces (Figs 7P, Q). This character state is common to F. parva described in this paper (Figs 7E, K). Liu et al. (2019, 2021) who described four Chinese species, F. brevicornis, F. flactoserrula, F. longitangia and F. xanthosoma, stated only “mandibles symmetrical” under the diagnosis of the genus, and details of mandibles are not given. These six species belong to the F. crenativora group. Other five species belong to the F. quercivora group and their mandibles differ from those of F. crenativora and F. parva and probably from four Chinese species. The mandibles of the F. quercivora group are slightly asymmetric. The left mandible is constricted in the middle with the middle part very gradually tapered or being the same thickness in the outer view (Figs 7F–I) and with a sharp apical carina on the anterior surface (Fig. 7R) and a low and dull apical carina on the posterior surface (Fig. 7S). The right mandible is constricted in the middle with the middle part being the same thickness or slightly thickened toward the apex in the outer view (Figs 7L–O) and with a low and dull apical carina on the anterior surface (Fig. 7R) and a sharp apical carina on the posterior surface (Fig. 7S). For “ F. quercivora Togashi, 2006 ” (= F. togashii), Togashi (2006) wrote “left mandible narrow, rather gradually tapered to apex” and gave the figure (fig. 4 in Togashi 2006), but his description and figure are not accurate (see Fig. 7F).
Prous et al. (2014) divided the character of mandibles into two states in the key to genera of world Nematinae, the couplet 6 “ a Left mandible markedly constricted near middle and right mandible tapered regularly towards apex” in the first line and “ aa Left and right mandible both tapered regularly towards apex” in the second line (see also the couplets 26 and 28), and treated Fagineura as having both states. However, the state ‘a’ does not agree with any Fagineura species (Figs 7D–O), and the state ‘aa’ almost agrees with F. crenativora and F. parva (Figs 7D, E, J, K) (and possibly also with the four Chinese species) but not with the F. quercivora group. We suggest some modification of the key in Remarks below.
- Setae on katepimeron. Vikberg & Zinovjev (in Shinohara et al. 2000) wrote “Anterior third of mesopleural katepimeron glabrous, posterior part pilose” for Fagineura. Prous et al. (2014) adopted the katepimeron extensively covered with setae as the generic character. In our specimens, the katepimeron is usually covered with setae extensively or moderately, but in F. parva and a few specimens of F. crenativora, the katepimeron has only a few or several setae. According to Liu et al. (2019), F. flactoserrula also has only a few setae on the katepimeron. This character is widely variable in the F. crenativora group, although the katepimeron is never entirely glabrous as in some species of the related genera such as Euura and Nematus.
- Distance between cenchri. Liu et al. (2019, 2021) wrote “distance between cenchri almost as long as breadth of a cenchrus” or “distance between cenchri as long as or shorter than breadth of a cenchrus” under the diagnosis of Fagineura. In our material, the ratio of the distance between cenchri to the major axis of a cenchrus is 0.8–1.5 × in the genus, 0.9–1.4 × in the F. crenativora group and 0.8–1.5 × in the F. quercivora group. This character is hardly useful to distinguish Fagineura and the two species groups from other nematine genera.
- Apical dilation of vein C of fore wing. Vikberg & Zinovjev (in Shinohara et al. 2000) and Liu et al. (2019, 2021) separated Fagineura from Pristiphora and its related genera by the less dilated vein C of the fore wing. This character is not very valuable to distinguish these genera. The apex of vein C is sometimes greatly dilated in the F. crenativora group (Fig. 8X), usually so in the F. quercivora group (Fig. 8Y) and sometimes less noticeably dilated in Pristiphora so that the ratio of the width of cell Sc to the width of vein C at the middle point of the base of vein Rs+M widely overlaps between the two genera. The ratio is 0.1–1.0 × in Fagineura (0.3–1.0 × in the F. crenativora group and 0.1–0.5 × in the F. quercivora group) and 0–0.4 × in Pristiphora in our material.
- Presence or absence of crossvein 2r-rs of fore wing. Previously known species of Fagineura have no crossvein 2r-rs. Therefore, the absence of crossvein 2r-rs has been adopted as the generic character by previous authors (Vikberg & Zinovjev in Shinohara et al. 2000, Liu et al. 2019, 2021). In this paper, we move Dineura quercivora Togashi, 1997 of which the holotype has crossvein 2r-rs to Fagineura (for the reason, see Remarks of Fagineura and F. quercivora).
- Apical emargination of valvula 3. Vikberg & Zinovjev (in Shinohara et al. 2000) considered the apically emarginate valvula 3 to be a character of the genus. However, F. xanthosoma of the F. crenativora group and several species of the F. quercivora group have the apically not or indistinctly emarginate valvula 3 (fig. 2f in Liu et al. 2019; Figs 9C, D, F, G).
- Presence or absence of pores in tangium of lancet. The pored tangium was considered the generic character of Fagineura by Vikberg & Zinovjev (in Shinohara et al. 2000) and Prous et al. (2014). However, the tangium of Fagineura flactoserrula has only one pore (fig. 1j in Liu et al. 2019), and those of F. parva and the F. quercivora group have no pores (Figs 11C, 12A–E, 13A–E).
- Presence or absence of ctenidium in most basal annulus of lancet. Liu et al. (2019, 2021) adopted the presence of a ctenidium in the annulus 1 of a lancet as the generic character. In all the members of the F. crenativora group, a ctenidium is present in the annulus 1 and it occurs in a transverse colorless area (Figs 11A–C; figs 2A–D in Liu et al. 2021). In F. parva, the ctenidium in the annulus 1 is small, but the colorless area with the ctenidium is well developed (Fig. 11C). In the F. quercivora group, the ctenidium and related colorless area are inconspicuous or absent (Figs 12A–E, 13A–E). The development of the colorless area with a ctenidium in the annulus 1 is a good character of the F. crenativora group.
- Tergum 8 of male. Liu et al. (2019) wrote “in males, the posterior end of tergum 8 with distinct apical projection” as one of the character to distinguish Fagineura from Pristiphora. Actually, certain members of Pristiphora also have a distinct procidentia (compare Figs 14A–C with figs 55–57 in Prous et al. 2017, figs 3Q, V in Hara et al. 2018, fig. 5H in Hara et al. 2021).
- Extra larval molt. The larva of F. crenativora has an extra molt after the feeding period (Shinohara et al. 2000). Vikberg & Zinovjev (in Shinohara et al. 2000) mentioned the presence of an extra larval molt as one of the generic characters. We observed that the mature larva of F. togashii of the F. quercivora group entered into the soil without an extra molt. The presence or absence of an extra molt may differ between the F. crenativora group and the F. quercivora group.
Remarks. The key to the genera of world Nematinae by Prous et al. (2014) needs some modification to identify Fagineura. The Fagineura species without crossvein 2r-rs go to the couplet 6 but part of them do not agree with either line of the couplet as stated in Character assessment (Shape of mandibles). To fit the part of Fagineura and some Nematinus (see the last paragraph), the state ‘aa’ in the second line of the couplet 6 needs to be modified as follows: Left and right mandible both tapered regularly towards apex or markedly constricted near middle, or left mandible tapered regularly towards apex and right mandible markedly constricted near middle (modified parts are shown in italics; the former modified part is for the part of Fagineura and the latter for some Nematinus). Fagineura goes through the modified second half of the couplet 6 to the couplet 18, but disagrees with either half of the couplet 18, because it has the subapical tooth of a tarsal claw not larger than the apical tooth* (‘aa’ in the second half), a short malar space (‘b’ in the first half) and a widely emarginate clypeus (‘cc’ in the second half) [* Liu et al. (2021) stated “inner tooth of tarsal claw longer than outer tooth” for “ F. quercivora ” (= F. togashii) probably based on fig. 11 by Togashi (2006), but fig. 11 is inaccurate (compare it with Fig. 11Q)]. By modifying the state “bb Malar space 1.0–2.0 times as long as diameter of front ocellus” in the second half to “bb Malar space 0.2 –2.0 times as long as diameter of front ocellus” (see Malar space length in Character assessment), Fagineura goes through the modified second half of the couplet 18 to the couplet 22 consisting of Fagineura and Euura. For the reasons mentioned in Character assessment (Setae on katepimeron and Presence or absence of pores in tangium of lancet), the couplet 22 needs to be modified as follows: 22(21) a Katepimeron extensively covered with hairs, sometimes with only few hairs. b Sawsheath slightly emarginate or not emarginate in dorsal view. c Tangium of lancet with or without campaniform sensilla............ Fagineura Vikberg and Zinovjev, 2000 in part - aa Katepimeron without hairs, sometimes with few hairs *. bb Sawsheath not emarginate in dorsal view. cc Tangium of lancet without campaniform sensilla............................... Euura Newman, 1837 in part
[* This modification is based on our material of gall-inducing Euura]
Even with this modified couplet, most of the Fagineura and Euura coming here will be distinguishable, but the male of F. parva and part of the male of F. crenativora are not separable from the males of some gall-inducing Euura. Their males are separated as follows: the tergal hollow of abdominal tergum 8 is well defined in the former (Figs 14A–C) but not clearly defined in the latter; a paraantennal field is mostly covered with setae in the former (Figs 6P, Q) but often widely glabrous in the latter; a median groove is present above a frontal pit in the former (Figs 6P, Q) but often absent in the latter.
In the key by Prous et al. (2014), some F. quercivora with crossvein 2r-rs run through the couplet 5 to the couplet 26 but their mandibles do not fit both the states ‘d’ and ‘dd’ in the couplet 26. The state ‘dd’ needs the following modification: Left and right mandible both tapered regularly towards apex or markedly constricted near middle, or left mandible markedly constricted near middle and right mandible tapered regularly towards apex. The same modification is needed for the state ‘aa’ of the couplet 28. With these modifications, some F. quercivora with crossvein 2r-rs run through the modified second half of the couplet 26 and the modified second half of the couplet 28 to the couplet 32 consisting of Moricella Rohwer, 1916 and Dineura Dahlbom, 1835. Fagineura quercivora differs from those genera by the anterior fore tibial spur with a velum (without a velum in those two genera) and the left and right mandible both markedly constricted near the middle (both tapered regularly towards the apex in those two genera).
We divide Fagineura into two species groups, the F. crenativora group and the F. quercivora group. These two groups have different mandibles, frontal pits, female cerci, lances, lancets and penis valves as stated in the couplet 1 of the key below. As far as we know about the ecology of Fagineura species, the larva of F. crenativora of the F. crenativora group feeds on Fagus and has an extra molt, but the larvae of all members of the F. quercivora group feed on Quercus and the larva of F. togashii of the F. quercivora group does not have an extra molt. We have not found any apomorphic character that suggests a close relationship between the two groups. The markedly constricted right mandible of the F. quercivora group (Figs 7L–O) appears to be an unusual feature in the Nematinae, though this character is also found in some Nematinus species (fig. 2I in Hara 2017). This fact may suggest that the F. quercivora group is closely related to Nematinus. On the other hand, the F. quercivora group has a markedly constricted left mandible (Figs 7F–H) like Euura, Nematus, Pristiphora and their related genera, and the larva of F. togashii of the F. quercivora group goes to the couplet 30 leading to part of Euura in the larval key of the West Palaearctic genera by Prous et al. (2019). Genetic study will be needed to clarify the relationship between the F. quercivora group and other nematines. We believe that it is best to place the F. quercivora group in Fagineura at the moment, because the group is more similar to the F. crenativora group than any other nematines and the genus classification of the Nematinae is still not stable, especially for East Asian species.
List of species groups and species of Fagineura
F. crenativora group:
F. brevicornis Liu, Li & Wei, 2021. China (Hubei).
F. crenativora Vikberg & Zinovjev, 2000. Japan (Hokkaido, Honshu, Shikoku, Kyushu).
F. flactoserrula Liu, Li & Wei, 2019. China (Hubei).
F. longitangia Liu, Li & Wei, 2021. China (Hunan).
F. parva Hara, sp. nov. Japan (Honshu, Shikoku).
F. xanthosoma Liu, Li & Wei, 2019. China (Hubei, Hunan).
F. quercivora group:
F. flavomaculata Hara, sp. nov. Japan (Honshu) and Korea.
F. fulvistriata Hara, sp. nov. Japan (Honshu).
F. glabella Hara, sp. nov. Japan (Honshu) and Korea.
F. quercivora (Togashi, 1997), comb. nov. [= Dineura quercivora Togashi, 1997]. Japan (Honshu) and Korea.
F. togashii Hara, nom. nov. [replacement name for F. quercivora Togashi, 2006; junior secondary homonym of F. quercivora (Togashi, 1997)]. Japan (Honshu, Kyushu) and Korea.
Key to species groups and species of Fagineura
1 Mandibles symmetric; each gradually tapered from middle to apex in outer view, with low and dull apical carina on each of anterior and posterior surfaces* (Figs 7A, D, E, J, K, P, Q). Frontal pit dorsally with median groove (Figs 6P, Q). Female: cercus about 4–6 × as long as wide (Figs 9A, B, I, J); lance without subdorsal carina on radix* (Figs 10A–C); lancet with sclerotized part before lamnium being narrow transverse band (Figs 11 A–C); annulus 1 anteriorly with transverse colorless area with ctenidium. Male: valvispina directed posteroventrally* (Figs 14K–N)......................... F. crenativora group ... 2
[* The character states are unknown for F. brevicornis, F. flactoserrula, F. longitangia and F. xanthosoma.]
- Mandibles slightly asymmetric; left one with middle part very gradually tapered or being same thickness in outer view, with sharp apical carina on anterior surface (Figs 7F–I, R); right one with middle part being same thickness or slightly thickened toward apex in outer view, with sharp apical carina on posterior surface (Figs 7L–O, S). Frontal pit dorsally without median groove (Figs 6R, S). Female: cercus about 8–9 × as long as wide (Figs 9C–H, K–P); lance with subdorsal carina on radix (Figs 10D–J); lancet with sclerotized part before lamnium large, extended anteriorly along olistheter (Figs 12A–E, 13A–E); annulus 1 anteriorly without colorless area and ctenidium, sometimes with colorless line or indistinct ctenidium. Male: valvispina directed posterodorsally* (Figs 14O, P).................................................... F. quercivora group ... 9
[* The character state is known only for F. togashii.]
2(1) Female.............................................................................................. 3
- Male*............................................................................................... 8
[* Only F. crenativora and F. parva; the males of F. brevicornis, F. flactoserrula, F. longitangia and F. xanthosoma are unknown.]
3(2) Valvula 3 with apex concave in dorsal view (Figs 9A, B)...................................................... 4
- Valvula 3 with apex pointed in dorsal view (fig. 2f in Liu et al. 2019)............................... F. xanthosoma, ♀
4(3) Valvula 3 narrower than long in dorsal view (Fig. 9B). Cercus posteriorly not beyond valvula 3 or slightly beyond it....... 5
- Valvula 3 wider than long in dorsal view (Fig. 9A). Cercus posteriorly far beyond valvula 3............. F. crenativora, ♀
5(4) Each flagellomere except for apical one slightly widened toward apex (Figs 2B, C)................................. 6
- Each flagellomere except for apical one markedly widened toward apex (figs 1A, 3A, E in Liu et al. 2021)...................................................................................................... F. brevicornis, ♀
6(5) Head black between eye and anterior tentorial pit (Fig. 2A). Katepimeron with only a few or several setae. Tangium of lancet with no or one pore (Fig. 11C; fig. 1j in Liu et al. 2019)....................................................... 7
- Head with pale area between eye and anterior tentorial pit (figs 3C, 4C in Liu et al. 2021). Katepimeron posteriorly covered with setae. Tangium of lancet with six pores (fig. 4I in Liu et al. 2021).............................. F. longitangia, ♀
7(6) Mesepisternum entirely dark brown to black (Fig. 2C). Lancet with transverse sclerotized band before lamnium very narrow and short, dorsally widely separated from olistheter (Fig. 11C); middle ctenidia long, dorsally almost in contact with neighboring ctenidia.................................................................................. F. parva, ♀
- Mesepisternum widely yellow brown (fig. 1e in Liu et al., 2019). Lancet with transverse sclerotized band before lamnium wide, dorsally extending to olistheter (fig. 1i in Liu et al., 2019); middle ctenidia widely separated from neighboring ctenidia (fig. 1h in Liu et al., 2019)...................................................................... F. flactoserrula, ♀
8(2) Head pale between eye and anterior tentorial pit (Fig. 1L). Thorax ventrally pale mostly or widely (Figs 1M, N). Abdomen with dorsum black basally and brown apically or mostly black and venter yellow. Paravalva with spinules ventrally (Fig. 14L).......................................................................................... F. crenativora, ♂
- Head black between eye and anterior tentorial pit (Fig. 2D). Thorax ventrally darkened (Figs 2E, F). Abdomen black, with subgenital plate brownish. Paravalva without spinules (Fig. 14N)........................................ F. parva, ♂
9(1) Mesepisternum not or very narrowly glabrous and barely or slightly expanded beside postspiracular sclerite (Figs 8I, J). Pale areas of body yellowish in color (Figs 2G–N, 4A–E)......................................................... 10
- Mesepisternum moderately or widely glabrous and distinctly expanded beside postspiracular sclerite (Figs 8K–N). Pale areas of body yellowish or reddish in color (Figs 4F–K, 5A–H).................................................... 11
10(9) Mesepisternum not glabrous and barely expanded beside postspiracular sclerite (Fig. 8I). In female, postocellar area black (Fig. 6F), mesepimeron darkened with dorsal margin and posterior part yellow (Fig. 2I), and abdomen with terga 1, 2 yellow and laterotergites 1–6 mostly yellow and laterotergites 7, 8 mostly black (Figs 2H, I)......................... F. togashii, ♀ ♂
- Mesepisternum very narrowly glabrous and slightly expanded beside postspiracular sclerite (Fig. 8J). In female, postocellar area yellow (Fig. 6H), mesepimeron entirely yellow to brown yellow (Fig. 4C), and abdomen with terga 1, 2 mostly black and laterotergites 1–8 yellow (Figs 4B, C)............................................... F. fulvistriata, ♀ (♂ unknown)
11(9) Pale areas of body yellowish in color (Figs 4F–H). Mesoscutum mostly black. Postocellar area darkened (Fig. 6I). Hind trochanter pale yellow (Fig. 4H). Mesoscutum except for posterolateral hollow mostly covered with setiferous punctures (Fig. 8B)...................................................................... F. flavomaculata, ♀ (♂ unknown)
- Pale areas of body mostly reddish in color (Figs 5A–J). Mesoscutum predominantly pale. Combination of other character states not as above........................................................................................ 12
12(11) Postocellar area predominantly or entirely black (Fig. 6K). Hind trochanter mostly black (Fig. 5C). Mesoscutum except for posterolateral hollow mostly covered with setiferous punctures (Fig. 8D), at most very sparsely punctured on anterior part of lateral lobe (Fig. 8C). Valvula 3 not concave apically in dorsal view (Fig. 9G).............. F. quercivora, ♀ (♂ unknown)
- Postocellar area red yellow (Fig. 6L), at most narrow median line and lateral margin black. Hind trochanter pale yellow (Fig. 5F). Mesoscutum except for posterolateral hollow widely smooth and glabrous (Fig. 8E). Valvula 3 slightly concave apically in dorsal view (Fig. 9H)............................................................. F. glabella, ♀ (♂ unknown)
description: Published as part of Hara, Hideho & Ibuki, Shinichi, 2022, A study of the genus Fagineura (Hymenoptera, Tenthredinidae, Nematinae), pp. 223-252 in Zootaxa 5116 (2) on pages 224-228, DOI: 10.11646/zootaxa.5116.2.3, http://zenodo.org/record/6367255