Saperda populnea lapponica, Wallin, Henrik, Kvamme, Torstein & Bergsten, Johannes, 2017

Wallin, Henrik, Kvamme, Torstein & Bergsten, Johannes, 2017, To be or not to be a subspecies: description of Saperdapopulnealapponica ssp. n. (Coleoptera, Cerambycidae) developing in downy willow (Salixlapponum L.), ZooKeys 691, pp. 103-148 : 117-124

Saperda populnea lapponica ssp. n. Figs 1, 6 b–c, e–f, 8b, 9b, 10 c–d, f, i–j, l, n, p–q, 11 b–c, 12 a–b, 13

Type material.

Holotype: ♂ NHRS (id NHRS-JLKB0000027179), BL 11.0mm, BW 3.0mm, from Sweden, Lappland, Lule lappmark, 2 km SE Kiruna, elev. 500 m, ”Aptasvaara”, reared from Salix lapponum 2014-07-09 (emerged 2015-02), leg. H. Wallin. Paratypes: Sweden: 1 ♀ BL 11.0 mm, same data as holotype, NHRS; 1 ♀ BL 10.0 mm, same data as holotype, CHW; 1 ♀ BL 9.5 mm and 1 ♂ BL 11.0 mm, same data as holotype, CHW; 1 ♀ BL 11.5 mm and 1 ♂ BL 10.5 mm, Sweden, Lappland, Lule lappmark, 20 km NW Kiruna, ”Gallugas”, reared from Salix lapponum 2015-06-11 (emerged 2015-06-24), leg. H. Wallin, CHW; 1 ♂ BL 11.0 mm, 1 ♂ BL 10.0 mm, 1 ♂ BL 9.5 mm and 1 ♀ BL 11.7 mm, Jämtland, Ånn (5 km W. Tångböle), Åre, reared from Salix lapponum 2016-09-12/13 (emerged 2017-01), leg. H. Wallin, CHW. 1 ♂ BL 12.0 mm, Lappland, Lule lappmark, Messaure, 1971-07-14/21, window trap, leg. T. Mûller, NHRS; 1 ♂ BL 10.5 mm, Lappland, Lule lappmark, Litnok, 1967-07-21, leg. S. Lundberg, NHRS; 1 ♂ BL 11.0 mm, Lappland, Torne lappmark, Sappisatsi, N. Vittangi, 1966-07-04, leg. S. Lundberg, NHRS; 1 ♂ BL 11.0 mm, Lappland, Torne lappmark, Soppero, 1968-06-15, ex larva reared from Salix lapponum , leg. S. Lundberg, NHRS; 1 ♂ BL 10.0 mm and 1 ♀ BL 10.5 mm, Lappland, Torne lappmark, Soppero, 1980-06-30, leg. S. Lundberg, NHRS; 2 ♂♂ BL 10.0 mm and 1 ♀ BL 9.5 mm, Lappland, Torne lappmark, Siltimuotka, Soppero, 1948-06-28, leg. N. Höglund, NHRS; 1 ♂ BL 11.5 mm, Lappland, Åsele lappmark, Kittelfjäll, 1972-06-28, leg. T-E. Leiler, NHRS; 1 ♀ BL 11.2 mm and 1 ♀ BL 10.5 mm, Lappland, Torne lappmark, Kiruna, ex larva from Salix lapponum , leg., E.v. Mentzer, CBE; 1 ♂ BL 11.0 mm, Jämtland, Tångböle, Åre, 1964-07-07 (locality J23 in a survey), leg. Waldén, Enckell & Hagberg, NMG; 1 ♂ BL 10.5 mm and 1 ♀ BL 13.0 mm, Lappland, Torne lappmark, Kiruna, Aptasvaara, 1976-07-10, on Salix lapponum , leg., C. Eliasson, GNM; 1 ♂ BL 10.3 mm, 1 ♂ BL 10.5 mm and 1 ♀ BL 12.4 mm, Lappland, Lycksele lappmark, Tärnaby, Juksjaur, 2013-06-30, on Salix lapponum , leg. R. Petterson, CRP; 1 ♂ BL 11.0 mm, Jämtland, Järvsand, 1986-06-19, leg. R. Petterson, CRP; 1 ♀ BL 12.0 mm, labelled “Zetterstedt”, ex coll. Gyllenhal, UUZM; 1 ♂ BL 10.0 mm, labelled “Zetterstedt”, ex coll. Gyllenhal, UUZM; 1 ♀ BL 10.0 mm, 1 ♂ BL 8.0 mm, 1 ♂ BL 10.2 mm, 1 ♂ BL 9.0 mm, Dalarna, Idre, 2014-06-26, reared from Salix lapponum , leg. Å. Lindelöw, CÅL; 1 ♀ BL 12.0 mm, 1 ♀ BL 11.3 mm, 1 ♂ BL 11.0 mm, 2 ♂♂ BL 10.0 mm, 2 ♂♂ BL 10.5 mm Lappland, Lule lappmark, 2 km SE Kiruna, elev. 500 m, ”Aptasvaara”, beaten from Salix lapponum 2014-07-09, leg. H. Wallin, CHW; 1 ♀ BL 12.0 mm, 1 ♀ BL 11.0 mm, 1 ♂ BL 9.5 mm, 1 ♂ BL 10.0 mm, Lappland, Lule lappmark, 2 km SE Kiruna, elev. 500 m, ”Aptasvaara”, reared from Salix lapponum 2014-07-09 (emerged 2015-02), leg. H. Wallin, CHW; 1 ♂ BL 11.0 mm, Härjedalen, Lövhögen, 1946-07-02, leg. N. Höglund, NHRS-COLE 00007432; 1 ♀ BL 11.0 mm, Torne lappmark, Silkimuotka, 1948-06-28, leg. N. Höglund, NHRS-COLE 00007433; 1 ♀ BL 11.0 mm, Torne lappmark, Silkimuotka, 1948-06-28, leg. N. Höglund, NHRS-COLE 00007438; 1 ♂ BL 10.0 mm, Torne lappmark, Silkimuotka, 1948-06-28, leg. N. Höglund, NHRS-COLE 00007436; 1 ♂ BL 11.0 mm, Lp. in., ex coll. Boheman, NHRS; 1 ♀ BL 11.2 mm, Lp. in., ex coll. Schönherr, NHRS; 1 ♀ BL 12.0 mm, Jämtland, ex coll. Rudolphi, NHRS; 1 ♂ BL 10.2 mm, Lp. i. S.U., NHRS. Norway: 1 ♂ BL 11.4 mm, 1 ♂ BL 10.9 mm, 1 ♂ BL 9.9 mm, 1 ♂ BL 10.1 mm, 1 ♀ BL 12.7 mm, 1 ♀ BL 13.5 mm HEN, Trysil: Ljørdalen, Skjærkjølen (EIS 65) 61°21'44.5"N, 12°40'06.3"E, 2014-VI-31, reared from Salix lapponum , Leg. T. Kvamme CTK; 1 ♂ BL 10.0 mm, BV, Ål: Vatsfjorden, 2006-07-17, leg. O. J. Lønnve, NHMO; 1 ♀ BL 12.5 mm, HEN, Trysil: Tangåtjønna, 2011-06-25, leg. P.K. Solevåg, CPKS; 1 ♂ BL 10.5 mm, OS, Nordre Land: Synfjellet, 1897-07-20/21, NIBIO; 1 ♀ BL 11.5 mm, HEN, Trysil: Ljørdalen, 2014-06-25, Salix lapponum , leg. Å. Lindelöw, CÅL; 1 ♀ BL 11.0 mm, 1 ♂ BL 11.0 mm and 1 ♂ BL 11.5 mm HEN, Skåret, RT90 6826517/1324435, 2014-06-25, Salix lapponum , leg. Å. Lindelöw, CÅL; 2 ♀♀ BL 12.5 mm, 1 ♀ BL 12.0 mm, 2 ♀♀ BL 13.0 mm, 1 ♀ BL 11.0 mm, 6 ♂♂ BL 11.0 mm, 1 ♂ BL 10.5 mm, 2 ♂♂ BL 10.0 mm, HEN, 5km NE Østby ( Ljørdalen), 2014-05-31, reared from Salix lapponum (emerged 2014-06-12), leg. H. Wallin, CHW; 2 ♀♀ BL 13.0 mm and 1 ♂ BL 11.0 mm, HEN, 5km SE Trysil, 2014-05-31, reared from Salix lapponum (emerged 2014-06-08), leg. H. Wallin, CHW. Finland: 2 ♂♂ BL 10.0 mm, Enontekiö, 1951-08-26, leg. Hellman, MZH; 1 ♀ BL 10.3 mm, Enontekiö, 1951-08-26, leg. Hellman, NHRS; 1 ♂ BL 10.5 mm, Kemijärvi, 1936-06-22, leg. Krogerus, MZH; 1 ♀ BL 12.4 mm, Finland, ex coll. Schönherr, NHRS no. 8146 E94. Russia: 1 ♂ BL 10.0 mm, BWBL 2.5 mm, Central Russia (Russia Merid.), leg. Zarisin, ex coll. C. Nyberg, MZH: 1 ♂ BL 8.7 mm, Central Russia (Russia Merid.), ex coll. Duske, MZH; 1 ♂ BL 10.6 mm, Petsamo (Petjenga), leg. Hellén (id 716), MZH.

Additional material examined.

The following specimens collected in Finland and available (through Boldsystems Public Data Portal) for photo examination includes: 1 ♀ COLFA181-10, Lapland, Inari, 1980-07-11, leg. Erkki Laasonen, id MP00443, ZMUO; 1 ♂ COLFA187-10, Lapland, Inari, 1993-08-26, leg. Juhani Itaemies, id MP00449, ZMUO.

Description.

A relatively small to medium-sized and subcylindrical subspecies with body length 9.5-13.0 mm in females and 8.0-12.0 mm in males, according to measurements from the present study. Body 3.1 times longer than wide in females and 3.4 times longer than wide in males (Fig. 6 b–c, e–f). Integument black, the compressed pubescence is yellowish to whitish (most northern populations) (Figs 6c, f) to reduced orange-brown pubescence (southern populations) (Fig. 6b, e). Elytra with numerous long erected dark brown hairs. The pubescence in the southern populations is relatively dense in both sexes. The yellowish to whitish pubescence in the northernmost populations (above the Arctic Circle) is strongly reduced resulting in exposed and shining integument in both sexes. The orange-brown pubescence is present but weakly extended laterally in females from southern populations and the yellowish to whitish pubescence in females from northern populations very weak laterally (Fig. 8b).

Head in females. Frons convex and broader than long (about 5 times broader than the width of one eye lobe), eyes with lower eye lobes slightly longer than broad and as long as gena below it. Genae posteriorly with long fringes of yellowish or whitish hairs and genae evenly narrowing towards mouthparts resulting in head being more “rounded” (Fig. 9b). Frons weakly covered with yellowish to whitish pubescence, and numerous dark brown, long and erected hairs. The area between antennal segments is shallowly impressed. Frons densely covered with orange-brown pubescence and numerous dark brown, long erect hairs. Genae posteriorly with long fringes of orange-brown hairs. Head in males: Frons convex and broader than long (about 4 times broader than the width of one eye lobe), eyes with lower eye lobes longer than broad and about 3 times longer than the short gena below. Head with frons rounded, genae straight and acutely narrowing towards mouthparts, frons weakly covered with whitish or orange- brown pubescence and numerous dark brown, long and erected hairs. Genae posteriorly with long fringes of orange-brown hairs. The area between antennal segments is shallowly impressed. Mouthparts. Frontoclypeal margin has a fringe of relatively long whitish pubescence and long, brown, suberect hairs. Clypeus glabrous except at base. Labrum with appressed, whitish pubescence and numerous long, suberect, orange-brown setae. Antennae. Short, slender, at the most extending beyond the middle of elytra by 2-3 antennomeres in females (Fig. 6 b–c). In males, the antennae reach by 3-4 antennomeres past the middle; thus, antennae are always shorter than body in males (Fig. 6 e–f). The segments from third segment are annulate. Annulation on antennal segments greyish and covering about ¾ of the anterior part of each antennal segment. The subconical, third segment is longer than first and fourth. Scape slender and coarsely punctured with a combination of large and small, shallow punctures and long black hairs. Thorax. Pronotum subcylindrical, slightly broader than long, lacking lateral spines. Pronotal disk convex, weak median line often with a glabrous and shining area medially, base shallowly impressed, coarse punctures except medially, densely covered with long erect and brown hairs, two broad lateral yellowish stripes with a weak median line interrupted medially. Prosternum densely pubescent with yellowish and whitish hairs. Elytra. 2.6-3.0 times longer than broad in females and 2.7-3.1 times longer than broad in males. No distinct carinae present on elytra. Parallel and weakly narrowing towards apices, apices narrowing and rounded, punctures coarse, deep, contiguous towards humeri and apices and confluent medially (especially in males where confluent punctures form short and weakly raised ridges transversally on each elytron), pubescence relatively weak to dense. There are generally eight relatively distinct and small to relatively large, yellowish to whitish spots on elytra, arranged in pairs: the first and third near the suture, spots in the third pair often elongated transversally or even divided into two spots each, spots in the fourth pair elongated transversally and placed on the middle of elytra in females (Fig. 6 b–c), Females from northern populations have irregular spots of yellowish to whitish pubescence between the third and fourth pair of spots and towards apices. No missing spots were seen in any of the examined specimens, but a few old worn specimens had very small i.e. obsolete spots on the elytra. The remaining part of elytra is covered with scattered yellowish or whitish pubescence and numerous long brown hairs. Scutellum. “U-shaped” and weakly covered with whitish hairs (southern populations) or entire scutellum glabrous (most northern populations). Hind wing. About 11.0 mm long in females and 9.0 mm long in males (Fig. 11 b–c). Covered with weak smoky tint. Several veins are broken with apical portions not connected to basal portions. MP3 (rudimentary), MP4 and AA vein broken. Radial cell very strong and complete. Legs. Relatively short, densely covered with fine whitish pubescent including tarsi, tarsal claws lacking a process. Venter. Densely covered with whitish to yellowish pubescence in both sexes, prosternal process narrow and flattened anteriorly. Mesosternum and abdominal ventrites are densely covered with yellowish or whitish pubescence and numerous yellowish and long, erected hairs. Posterior margin of sternite VII rounded and often deeply notched on medially. Male terminalia. Aedeagus 2.0-2.3 mm long, evenly curved towards apex and compressed dorso-ventrally (Fig. 10f), dorsal surface smooth and shining with apical part weakly narrowed towards apex (Fig. 10 c–d). Tegmen with parameres 2.1-2.5 mm longer and straight dorso-ventrally (Fig. 10l). Parameres acutely narrowing towards apex, with dorsal surface glabrous and shining, or (rarely) with entire surface densely covered with punctures and suberected setae. The inner margins well-separated and diverging towards apices (Figs 10 i–j). Tergite VIII 0.6-1.0 mm long, relatively large and rounded with the posterior margin concave in the middle and densely covered with white pubescence and numerous long brown hairs (Fig. 10p-q). Sclerites inside internal sac 1.7-2.1 mm long consisting of three parallel “shaft-like” structures, of which the apical end (top) is elongated and posterior end blunt and acutely narrowing towards posterior end (Fig. 10n). The colour of male genitalia is yellowish to dark brown. Female terminalia. Tignum almost straight, 6.5-8.2 mm long (width 0.1-0.2 mm at the widest point apically). Tergite VIII posterior margin (width: 1.0 mm) with a few brown hairs. The colour is brown. Spermathecal capsule: strongly sclerotised, yellowish, round and supplied with a short shaft, diameter: 0.5 mm.

Remarks.

morphological characteristics are mainly based on type specimens, either collected on, or reared from branches of Salix lapponum . S. populnea lapponica ssp. n. is separated from S. populnea populnea by the overall smaller body size, shorter antennae in both sexes, reduced pubescence on thorax and elytra, mainly yellowish to whitish pubescence, reduced or absent pubescence on scutellum and short frons in females which is giving the appearance of a rounded head (Fig. 8b). The characters presented herein are mainly based on newly hatched and fully sclerotised specimens. Small, dark and less pubescent specimens are easily recognized in collections in Fennoscandia and were in most cases, found to belong to the new subspecies S. populnea lapponica ssp. n. There are variations in the body size and colour pattern on elytra between the various populations of S. populnea lapponica ssp. n. The slightly larger specimens occurring in the southern populations near Trysil, Norway, have more distinct spots on elytra. The darker and smaller specimens from the northern populations, occurring in the northern Scandinavian mountain range near e. g Kiruna, also have intermediate forms occurring e.g. in Juksjaur near Tärnaby. The darker and slightly smaller specimens have more reduced spots on elytra. No such geographical variation in body size and colour pattern has been found in S. populnea populnea in Fennoscandia.

Etymology.

The name is an adjective used as a substantive in the genitive case derived from the specific name of the host plant Salix lapponum .

Distribution.

The distribution of S. populnea lapponica ssp. n. is within the distribution of Salix lapponum in Fennoscandia ( Hultén 1971). The most southern populations of S. populnea lapponica ssp. n. occur near Trysil, Norway, while the most northern populations occur north of the Arctic Circle (Fig. 13). Since Salix lapponum is distributed eastwards in Siberia approximately to the Jenisej Valley ( Hultén and Fries 1986), it is possible that S. populnea lapponica ssp. n. has a much wider distribution in Russia than we are able to show in the present paper.

Biology.

The attacks are similar to S. populnea populnea where females form a "U-shaped lid" in the bark under which an egg is deposited. Stems and branches around 1-2 cm in diameter are used. However, normally no galls are formed by the host tree (Fig. 12 a–b). The attacks can be massive and one single stem can contain up to 30 attacks (Fig. 12a). Larvae can live during a number of consecutive years since old exit holes are present together with live larvae. It is, therefore, likely that several generations of beetles can develop within the same stem of Salix lapponum . Exit holes are normally slightly larger when made by female beetles compared to male, reflecting the differences in size and shape. The development takes at least 2 years, since both small and full-grown larvae were found in stems of Salix lapponum after adults had emerged. The localities are wetter than localities where S. populnea populnea are found, since Populus tremula do not occur in biotopes where S. lapponum occur. As a consequence, S. populnea populnea and S. populnea lapponica ssp. n. live in well separated habitats.

In addition, parasites including wasps and flies frequently attack S. populnea populnea ( Schwenke 1974, Pulkinn and Yang 1984, Georgiev 2001). Very few such parasites have been collected from stems attacked by S. populnea lapponica ssp. n. which might be due to climatic factors. However, we did recover two parasitoid wasps of the family Ichneumonidae from downy willow hatching wood with Saperda populnea lapponica ssp. n. attacks. These were identified as one Poemenia hectica (Gravenhorst, 1829) ( Poemeniinae ) and one Campopleginae , possibly belonging to the genus Pyracmon (det. Jacek Hilszczański). Unfortunately, the second specimen was damaged during post transfer and could therefore not be identified with certainty. While Campopleginae includes species known as parasitoids of saproxylic beetles, Poemenia is known as a parasitoid of wood-nesting wasp larvae, so that it may not have been (directly) related to the Saperda populnea lapponica ssp. n. larvae.