Phyllocnistis triandricola, Voith & Aarvik & Berggren & Bengtsson & Hellberg & Mutanen & Slagsvold & Wieser, 2023

Voith, Reidar J. D. I., Aarvik, Leif, Berggren, Kai, Bengtsson, Bengt Åke, Hellberg, Hasse, Mutanen, Marko, Slagsvold, Per Kristian & Wieser, Christian, 2023, Taxonomy of the Phyllocnistis saligna (Zeller, 1839) complex (Lepidoptera, Gracillariidae) in North and Central Europe, with the description of a new species, Norwegian Journal of Entomology 70, pp. 10-28 : 22-25

Remarks on Phyllocnistis saligna

Examined material. 1♀, SWEDEN, Uppland, Alvik , 11.X.2011, genitalia slide RVO 2021-6 ; 1♂, same locality, ex pupa Salix 11.X.2021, genitalia slide RVO 3672, BOLD sample ID: NLON1100- 22 ; 1♂, Uppland, Kista , 28.IX.2012, genitalia slide RVO 2021-7, BOLD sample ID: NLON947- 21 ; 1♀, same locality, ex pupa Salix 9.X.2021, genitalia slide RVO 3673, BOLD sample ID: NLON1101-22 ; 1♀, same locality, 19.X.2011, genitalia slide RVO 2021-8, BOLD sample ID: NLON948-21 ; 1♀, ex pupa Salix 23.IX.2021, genitalia slide RVO 3674,, BOLD sample ID: NLON1102-22 . All specimens H . Hellberg leg. & coll.; 1♀, LATVIA, Rig. Carnikava , ex l. Salix 15–20.VII.2011, leg. N . Savenkov , BOLD sample ID: MM20616 coll. ZMUO; 1♂ 1♀, same data, coll. NHMO ; 1 ex, FINLAND, Nylandia, Helsinki, Vuosaari 60.1729 N 25.1083 E, 21–22. VII.2011, leg. Jari Junnilainen, BOLD sample ID: MM22736 , coll. ZMUO; 35 ex, FINLAND, Nylandia, Espoo 66814:83731, larvae/pupae on Salix purpurea 8.IX.2019, leg. Tomi Mutanen, coll. ZMUO ; 8 ex FINLAND, Regio aboensis, Salo 6704:3287, larvae on Salix purpurea 28.VII.2020, leg. Marko Mutanen & Tomi Mutanen, coll. ZMUO .

Molecular diagnosis. Ph. saligna with BIN: BOLD:AAQ1589 forms a distinct cluster with the nearest neighbour being BIN: BOLD:AAL5482 ( Ph. asiatica ) with a p-distance of 4.49 %. Intraspecific variability of BIN of Ph. saligna is 1.28 %. In the phylogenetic tree ( Fig. 18 ), Ph. saligna is a sister-species to Ph. asiatica , although

Norwegian Journal of Entomology 70, 10–28 (2023)

this association is only poorly supported. Together with Ph. triandricola sp. n., the triplet forms a strongly supported clade (BS=99 %). However, it is likely that this clade includes another undescribed species with BIN: BOLD:ACL6215 not included in our dataset.

Observations on biology. In Sweden bred from an imported or cultivated narrow leaved Salix species, probably Salix purpurea L. In Finland, numerous specimens have been reared from Salix purpurea , which occurs there only as an ornamental plant. Based on observations made there, the species may be monophagous on this Salix . Where present, it often occurs in great numbers as larvae. The oviposition probably takes place on the underside of the leaves, and the mines are all observed there. This species mines both in the leaves and in the twig ( Figure 26 ). The newly hatched larva mines the leaf in a zigzag manner forming a mine that eventually fills a noticeable part of the leaf. When most of the epidermis has been consumed it will leave the leaf through the petiole and sometimes continue in the twig for a new leaf some 10–20 cm away, or it enters a new leaf immediately through an adjacent petiole. The new leaf is mined in the same way as the first before pupation takes place in a cocoon spun in a cigar-shaped fold at the underside of the leaf margin. The larva, when mining the stem, has also been observed making a 180 degree turn like Ph. triandricola sp. n. The latter species mines mainly in the stem and uses the leaves only at the start and end of the larval stage. In contrast, it seems that Ph. saligna uses the leaves as its main habitat, and that the stems are mined only occasionally. It appears that Ph. saligna has two or three generations a year. Fresh mines and imagines have been found as late as late September and October.

Distribution. According to our data Ph. saligna is present in Central Sweden, Finland, Latvia and in Austria. Data from the BOLD database indicate (BIN: BOLD:AAQ1589) occurrence also in France, Germany, Italy and Spain. It has also been recorded from the United Kingdom, but consideration will now have to be given as to whether Ph. saligna does indeed occur there as a result of Ph. asiatica being discovered in Cambridge (see below).

Figures

FIGURE 18. A Maximum Likelihood tree of 478 specimens and 13 species or putative species of Phyllocnistis Zeller, 1848, of which 12 represents the clade associated with Salicaceae plants. The tree was rooted on Ph. citrella Stainton, 1856. The node confidence was estimated based on 500 bootstrap pseudoreplicates. In general, BS support values for deeper nodes are relatively low, highlighting that phylogenetic relationships between species should be considered as tentative.Species form highly supported clusters except for the Ph. labyrinthella/ populiella/xenia complex, which all belong to the same BIN and show rather minor genetic divergences.

FIGURE 26. Mines of Phyllocnistis saligna (Zeller, 1837) from Sweden: Kista. Photo: H. Hellberg.