Heterarthrus kamtchaticus (Malaise, 1931), species revocata

Liston, Andrew, Mutanen, Marko & Viitasaari, Matti, 2019, On the taxonomy of Heterarthrus (Hymenoptera, Tenthredinidae), with a review of the West Palaearctic species, Journal of Hymenoptera Research 72, pp. 83-126 : 98-99

Heterarthrus kamtchaticus (Malaise, 1931), species revocata

Phyllotoma kamtchatica Malaise, 1931: 29. Syntypes ♀, in NHRS (lectotype designated below). Type locality: Russia, Kamtchatka, Elisowo.

Heterarthrus kamtchaticus . Lindqvist (1969): synonymised with H. vagans ( Fallén, 1808). Ermolenko (1981): treated as valid species, recorded from Kuriles, associated with Alnus . Taeger et al. (2010): Listed as synonym of H. vagans ( Fallén, 1808)

Heterarthrus aihinoensis Haris, 2006: 193. Holotype ♀, in HNHM (examined). Type locality: Russia, Kuriles, Aihino. Syn. nov.

Type material examined.

Lectotype Phyllotoma kamtchatica , here designated: ♀ "Kamtschatka Malaise", “E”, “Typus”, “NHRS-HEVA000001264”, "Syntype Phyllotoma kamtchatica Malaise, 1931 teste Taeger & Vardal 2011" (NHRS). Paralectotype: ♀, labels as for lectotype, but: “Paratypus”, “NHRS-HEVA000001265” (NHRS).

Holotype Heterarthrus aihinoensis : ♀ “Szovjetunió, Kuril-szigetek, Kunasir-sziget, Aihino", 30.vii.1973. leg. Ermolenko", "Holotypus Heterarthrus aihinoensis sp. nov. Haris 2006 ", "Hungarian Natural History Museum Hymenoptera Coll. Budapest", “DEI-GISHym31973” (HNHM).

Remarks.

The coloration of female Heterarthrus vagans is highly variable (see under that name). Lindqvist (1969) examined the syntypes of P. kamtchatica and concluded that these are indistinguishable from very dark-coloured females of H. vagans . He also observed that nearly completely dark-bodied female H. vagans occur in Finland, and wrote that [translated from German] "While the abdomen of the nominate form of H. vagans is completely or mostly reddish-yellow, in H. kamtchaticus this is so extensively black, that at most the base of the venter is slightly pale. All other body parts as well as the wings are similarly darker than in the nominate form". He also examined the lancets of the P. kamtchatica types, and found no differences to H. vagans . We disagree with parts of his statement: The P. kamtchatica types show no trace of pale colour on the basal abdominal sterna, the head has a pale pattern which is as extensive as any examined H. vagans females, but slightly differently distributed ( Fig. 48 ), the fore wing is basally smoky up to about the level of the pterostigma and less so at the apex (whereas the fore wing of vagans is uniformly smoky), and the tegulae are paler than the rest of thorax (always black in examined H. vagans , apart from a specimen from Corsica). Perhaps more significantly, female H. kamtchaticus have smaller eyes than H. vagans : malar space of H. kamtchaticus 0.27-0.33 × height of eye, in vagans 0.18-0.22 × height of eye. Furthermore, unlike Lindqvist, we did observe differences between the shape of the lancet sawteeth: in H. kamtchaticus they are longer in proportion to their height, the denticles more numerous, with basal denticle smaller and more acute, and the basal and median teeth are less widely separated from each other (compare Fig. 50 with Fig. 49 ). These differences are significantly greater than the range of infraspecific variability normally encountered in Heterarthrus . Probably, these two taxa are indeed closely related. Genetic data, currently lacking for H. kamtchaticus , should help to clarify their relationship, but for the present, it seems preferable to treat them as separate species.

Perhaps because its coloration is somewhat similar to female H. ochropoda , Haris (2006) compared H. aihinoensis to that species, rather than H. vagans , although the sawsheath shape of the H. aihinoensis holotype strongly resembles the latter. We found only one difference between the H. aihinoensis holotype and the P. kamtchatica types: the tegulae of the former are slightly paler. This single difference does not seem likely to be significant. Even the colour pattern of their faces is very similar. Accordingly, we propose the synonymy of H. aihinoensis and H. kamtchaticus .

Host plants and biology.

Associated by Ermolenko (1981) with an Alnus species, because adults were collected from this.

Distribution.

Kamtchatka ( Malaise 1931), Kuriles ( Ermolenko 1981), and possibly north-east China ( Wei 1998).

Figures

Figures 41 - 48. Heterarthrus 41 - 46 H. fiora ♀: 41, 42 head dorsal at different viewing angles, holotype 43 DEI-GISHym 83900 lateral 44, 45 DEI-GISHym 83900 sawsheath dorsal, lateral 46 DEI-GISHym 31977 antenna 47, 48 head frontal ♀: 47 H. vagans DEI-GISHym 11091 48 H. kamtchaticus (H. aihinoensis holotype). Scale bar: 1 mm.

Figures 49 - 54. Heterarthrus 49, 50 lancets: 49 H. vagans DEI-GISHym 31974 50 H. kamtchaticus HEVA- 1264 51 - 54 H. vikbergi sp. nov. ♀ DEI-GISHym 83572: 51 lateral 52 head frontal 53 head dorsal 54 abdomen apex ventral. Scale bar: 1 mm.