Pristiphora conjugata (Dahlbom, 1835)

Prous, Marko, Kramp, Katja & Liston 1, Veli VikbergAndrew, 2017, North-Western Palaearctic species of Pristiphora (Hymenoptera, Tenthredinidae), Journal of Hymenoptera Research 59, pp. 1-190 : 86

Pristiphora conjugata (Dahlbom, 1835) Figs 43, 49, 153-155, 255, 257, 259

Nematus gonymelas Stephens, 1829: 329. Not available. Nomen nudum.

Nematus conjugatus Dahlbom, 1835a: 21-22, 40. Lectotype ♂ (MZLU2014464; here designated) in MZLU, examined. Type locality: Vallkärra, Skåne, Sweden.

Nematus gonymelas Stephens, 1835: 34. Syntype(s) possibly in BMNH, not examined. Type locality: Britain ( Kirby 1882). Synonymised with P. conjugata by Konow (1897b).

Nematus (Nematus) conjugatus Dahlbom, 1835b: 8. Not available. Nomen nudum.

Nematus discipennis Herrich-Schäffer, 1840: 176. Note. Replacement name for "Pristoph. myosotidis Lep. Pz. 98. 13. Tenthr.".

Nematus discoidalis Thomson, 1888: 1209-1210. Syntype ♀ in MZLU, not examined. Type locality: Örtofta, Skåne, Sweden. Synonymised with P. conjugata by Vikberg (1982).

Pristiphora conjugata var. forsiusi Enslin, 1916: 534. Lectotype ♀ (GBIF-GISHym3282; here designated) in ZSM, examined. Type locality: Karislojo, Uusimaa, Finland.

Pristiphora conjugata var. ulbrichti Enslin, 1916: 534. Lectotype ♀ (GBIF-GISHym3450; here designated) in ZSM, examined. Type locality: Krefeld (Crefeld), North Rhine-Westphalia, Germany.

Similar species.

The most similar species in Europe are P. testacea , P. pallidiventris , and P. nigricans , which have a unicoloured (dark or pale) pterostigma (bicoloured in P. conjugata , but this is less clear in males). Lancets and penis valves can also be distinguished from other species (see the Key). Darker specimens of P. conjugata (e.g. females with black mesepisternum and dorsally black abdomen) feeding on Salix have been treated as a separate species, P. forsiusi Enslin ( Lindqvist 1964, Kangas 1985), although according to Zhelochovtsev and Zinovjev (1988) both conjugata and forsiusi feed on Populus and Salix . There is no gap in colour variation between paler and darker forms (two females reared from Salix fragilis by Ewald Altenhofer have a partly pale mesepisternum). There are no reliable differences in the structure of the lancets or penis valves either and the slight differences do not appear to correlate with the host plant. The only indication that there might be two species involved, is that the males reared from Salix have a completely or nearly completely black propleuron, which is extensively pale in males reared from Populus . More specimens should be reared to test this weak correlation. If there are two species, one feeding on Salix , the other on Populus , the name conjugata Dahlbom should be applied to the one feeding on Salix , as the only available type specimen (designated here as the lectotype) was reared from Salix fragilis ( Dahlbom 1835a), which is a male with an almost completely black propleuron.

Genetic data.

Based on a COI barcode sequences, P. conjugata forms its own BIN cluster (BOLD:ABV4426) (Fig. 5). Maximum distance within the BIN is 1.68%. The nearest neighbour to BOLD:ABV4426, diverging by minimum of 3.69%, is BOLD:ACG2245 ( P. beijingensis ?). Based on nuclear data, maximum within species divergence is 0.4% (based on two specimens and NaK) and the nearest neighbour is 1.2% different ( P. wesmaeli , only NaK).

Host plants.

Populus nigra L. (Pesarini and Turrisi 2001, Okutani 1970), P. tremula L. ( Okutani 1970, Boevé 1990, Pschorn-Walcher and Altenhofer 2000), Populus x canadensis Moench ( Martelli 1954), Salix alba L. ( Delmas 1926), S. caprea L. ( Weiffenbach 1985), S. cinerea L. ( Benander 1966), S. fragilis L. ( Dahlbom 1835a, Boevé 1990, Pschorn-Walcher and Altenhofer 2006, and based on the adults reared from larvae by Ewald Altenhofer), S. pentandra L. ( Benander 1966, Kangas 1985).

Distribution and material examined.

Palaearctic. Specimens studied are from Austria, Estonia, Finland, Germany, and Sweden.