Heptamelus viitasaarii Liston, Mutanen &amp; Prous 2022, sp. nov.
Creators: name: Liston, Andrew
name: Mutanen, Marko
name: Heidemaa, Mikk
name: Blank, Stephan M.
name: Kiljunen, Niina
name: Taeger, Andreas
name: Viitasaari, Matti
name: Vikberg, Veli
name: Wutke, Saskia
name: Prous, Marko
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Tenthredinidae
Heptamelus
Heptamelus viitasaarii

description: Heptamelus viitasaarii Liston, Mutanen &amp; Prous sp. nov. Description. <b>Female.</b> Figs 23, 24A-C, 26A, B <i>Colour.</i> Fig. 26A, B. Black. Pale are: palpi, tegula, legs (except for arioli and extreme inner tip of metatibia); in fore wing base and apex of costa, apex of subcostal, base of stigma (Fig. 23A), R1, 1A, 2A+3A [color differences between veins of hind wing not clearly definable]; margins of median excision of abdominal tergum 1, medio-distal part of terga 2-4 (-6) [pale area on tergum 3 is the largest of these], all sterna, more or less the downturned parts of terga 2-8, more or less hypopygium and ovipositor valvifer 2. Wing membranes hyaline. <i>Head.</i> Pedicel about as long as scape. Head in lateral view with widest point on temple about equal to length of pedicel (Fig. 23E). Malar space slightly shorter than diameter of anterior ocellus. Lowest part of gena densely sculptured, without shining interspaces between the ill-defined pits (Fig. 23E). Clypeus densely pitted, weakly shiny; anterior margin widely emarginate, to about 0.4 of its length (Fig. 23D). Setae on upper head as long, or longer than, diameter of anterior ocellus (Fig. 23E). <i>Thorax.</i> Whole pronotum except for small antero-ventral area dull, with sculpture (Fig. 23H). Pits on upper mesepisternum large and well-defined (Fig. 23H). Mesoscutellum with large, scattered pits anteriorly and laterally, interspaces shiny; medially and posteriorly nearly without pits and entirely unsculptured (Fig. 23F). Anterior of mesoscutellar appendage densely pitted, with numerous setae, only small posterior area unpitted (Fig. 23F). <i>Abdomen.</i> Anterior of tergum 1 densely setose. Terga 2 and 3 glabrous. Terga increasingly setose from tergum 4 to apex of abdomen. Weak surface sculpture on tergum 2 becoming stronger on more distal terga. Sawsheath in dorsal view broad, with blunt tip (Fig. 24C). In lateral view exposed length of cercus about 0.5 × as long as exposed upper length of valvula 3 (Fig. 23G). Lancet (Fig. 24B, C): 13-14 serrulae; apical serrulae short and high. <i>Body length</i>: 4.5-8.0 mm <b>Male.</b> Figs 24D, 26C Similar to female, except for: red-brown antennal flagellum with basal two antennomeres more or less black; metatibiae completely pale; abdomen completely dark with small, obscure pale markings medially on terga 3-5. Penis valve: Fig. 24D. <i>Body length</i>: 4.5-5.5 mm <i>Variability</i>: 5-6 flagellomeres, depending on whether or not the distal one is subdivided; the proportions of this antennomere are thus highly variable. Number of pits on upper mesepisternum variable. The scape and pedicel of females may be more or less pale. Type material. <i>Holotype</i> &amp;female; (ZMUO.044130). Type locality: Finland, Karelia borealis, Kitee Otravaara, YKJ grid coordinates: 6868:3663 [61.8877N 30.1096E]; 04.08.2019 [larva] in <i>Athyrium filix-femina</i> (L.), Rearing 380/2019, leg. M. Mutanen. Labels white, printed, except for red holotype label. Deposited in the ZMUO. <b> <i>Paratypes</i>.</b> Total: 92&amp;female;, 6&amp;male;. Finland [leg. M. Mutanen and in ZMUO unless otherwise stated]: Karelia borealis, Kitee: Otravaara [Type locality]; 17&amp;female; (including ZMUO.044126, ZMUO.044127, ZMUO.044128, ZMUO.044129, ZMUO.044131, ZMUO.044132, ZMUO.044133, ZMUO.044134, ZMUO.044135, ZMUO.044136), 04.08.2019 [larvae] in <i>Athyrium filix-femina</i> (L.), Rearing 380/2019. 7&amp;female; (including ZMUO.034957, ZMUO.034958, ZMUO.034959), Otravaara, YKJ grid coordinates: 6868:3663 [61.888°N, 30.110°E], 19.06.2018. 30&amp;female; (including ZMUO.058509, ZMUO.058510, ZMUO.058511, ZMUO.058512, ZMUO.058513, ZMUO.058514, ZMUO.058515, ZMUO.058516, ZMUO.058517, ZMUO.058518, ZMUO.058519, ZMUO.058520), Otravaara, YKJ grid coordinates: 6868:3663 [61.888°N, 30.110°E], 24.08.2020, leg. M. Mutanen and M. Prous. Host: <i>Athyrium filix-femina</i>, rearing 174/2020. 1&amp;female; (ZMUO.046037), 15.06.2020. ZMUO and SDEI. Otravaara, YKJ grid coordinates: 6868:3664 [61.887°N, 30.129°E]; 8&amp;female; (including ZMUO.034859, ZMUO.034860), 19.06.2018. 1&amp;female; (ZMUO.034995), 18.06.2018. Pajarinmäki, YKJ grid coordinates: 68899:36670 [62.078°N, 30.197°E]; 1&amp;female; (ZMUO.032885), at light, 11.07.2017 [end date of about 5-day period]. 1&amp;female; (ZMUO.033391), at light, 18.07.2017 [end date of about 7-day period]. 2&amp;female; (including ZMUO.034899), 20.06.2018. 1&amp;male; (ZMUO.061917), 14.06.2021, leg. A. Liston, M. Mutanen, M. Prous. 1&amp;male; (ZMUO.061893), 15.06.2021, leg. N. Kiljunen, A. Liston, M. Mutanen, M. Prous. 4&amp;male; 8 &amp;female;&amp;female; (including ZMUO.060946, ZMUO.060947, ZMUO.060948, ZMUO.060949, ZMUO.060950, ZMUO.060951, ZMUO.060952, ZMUO.060953, ZMUO.060954, ZMUO.060955, ZMUO.058165), 18.06.2021, leg. N. Kiljunen, A. Liston, M. Mutanen, M. Prous. 2 larvae from <i>Matteuccia struthiopteris</i> (L.) (ZMUO.060557, ZMUO.060558) and 2 larvae from <i>Athyrium filix-femina</i> (L.) (ZMUO.060561, ZMUO.060562), 26.07.2021, leg. M. Mutanen, M. Prous. Papinniemi, YKJ grid coordinates: 6883:3656 [62.025°N, 29.990°E]; 6&amp;female; (including ZMUO.034761, ZMUO.034762), 18.06.2018, ZMUO and SDEI. 1&amp;female; (ZMUO.040497), 12.06.2019. Puhos, YKJ grid coordinates: 6889:3653 [62.080°N, 29.938°E]; 2&amp;female; (including ZMUO.034968), 20.06.2018. Hiidensaari, YKJ grid coordinates: 6891:3668 [62.092°N, 30.226°E]; 1&amp;female; (ZMUO.034908), 20.06.2018. Potoskavaara, YKJ grid coordinates: 6893:3670 [62.109°N, 30.266°E]; 1&amp;female; (ZMUO.046430), 28.06.2020, leg. Tupu Vuorinen. Satulavaara, YKJ grid coordinates: 6877:3672 [61.964°N, 30.289°E]; 3&amp;female; (including ZMUO.061792, SDEI-GISHym14061), 14.06.2021, leg. A. Liston, M. Mutanen and M. Prous. ZMUO and SDEI. Karelia australis: Imatra Kaikkallio, YKJ grid coordinates: 6778:3594 [61.104°N, 28.752°E]; 1&amp;female; (ZMUO.058146), 16.06.2021, leg. A. Liston, M. Mutanen, N. Kiljunen, M. Prous. Joutseno Kuurmanpohja Sunninmäki [61.071°N, 28.731°E]; 1&amp;female; (ZMUO.016815), 06.06.2015, leg. Jussi Vilen, coll. Matti Viitasaari. Tavastia australis: Kangasala Keisarinharju, YKJ grid coordinates: 6818:3347 [61.444°N, 24.141°E]; 1&amp;female; (ZMUO.061964), 08.06.2021. Other material. Finland: Nylandia, Vantaa, YKJ grid coordinates: 669:37, 17.06.2021, 1&amp;female;, leg. Miikka Friman. Etymology. Named after Matti Viitasaari, who first recognised a very large female of this species as probably not belonging to <i>Heptamelus ochroleucus</i> or <i>H. dahlbomi</i>. Habitat. Damp, shady places in woodland. Biology. Many female specimens have been reared from larvae in <i>Athyrium filix-femina</i> (L.) Roth. (Fig. 25). Larvae found abundantly in 2021 in <i>Matteucia struthiopteris</i> (L.) Tod. in Kitee, Finland, were provisionally identified as <i>H. viitasaarii</i> by genetic comparison (identical to adults), as later confirmed when females started to emerge in 2022. The larvae feed inside the rachis, eating alternate portions nearly completely, or only partly (Fig. 25B, C). This results internally in a “ladder-like” appearance, which is externally clearly visible, especially against the light (Fig. 25A). This feeding habit is, however, possibly widespread in <i>Heptamelus</i>: at least <i>H. dahlbomi</i> larvae feed in the same way. Larvae of <i>H. viitasaarii</i> in <i>M. struthiopteris</i> regularly overwinter in a chamber made within the fertile fronds at the base of the stem. Strangely, no males have so far been reared, and the few males so far netted are all from a single locality (within an area of less than 1km2). It was observed that adults reared from plants of different size varied very much in body size, and that the smallest individuals had been feeding on the smallest plant, with correspondingly thin stalks. Distribution. Finland (North and South Karelia, Tavastia, and Helsinki area), Russia (Moscow). The record from Moscow was published by Vikberg (2017) as <i>Heptamelus ochroleucus</i>. Differential diagnosis. The characters which are most useful for the identification of European <i>Heptamelus</i> species are presented below in a key. The extensively pitted and setose mesoscutellar appendage distinguishes <i>H. viitasaarii</i> from the two other European species, as well as <i>H. magnocularis</i> Malaise, 1931 (Malaise 1931b) from the Russian Far East (see Liston et al. 2018). Note that all body parts of <i>H. viitasaarii</i> are conspicuously more densely setose, and pitted, than most other <i>Heptamelus</i> species which we have so far examined. From the females of <i>Heptamelus dahlbomi</i>, <i>H. ochroleucus</i>, <i>H. magnocularis</i>, <i>H. montanus</i> Togashi, 1961, and <i>H. takeuchii</i> Togashi, 1961 (the latter two from Japan), <i>H. viitasaarii</i> differs in its much shorter and higher apical serrulae of the lancet (Fig. 24A, B). <i>Heptamelus viitasaarii</i> has a wider sawsheath in dorsal view than either <i>H. dahlbomi</i> or <i>H. ochroleucus</i>. <i>Heptamelus japonicus</i> Togashi, 1961, only known in the male sex, differs from <i>H. viitasaarii</i> in its entirely pale thorax, abdomen and fore wing pterostigma. The male of <i>H. takeuchii</i> differs from <i>H. viitasaarii</i> in its more shallowly emarginate and smoother clypeus, and the pale abdominal sternum 9. The male of <i>H. montanus</i> resembles that of <i>H. viitasaarii</i> in coloration, but as in females of these species, the clypeus of <i>H. montanus</i> is much less deeply emarginate (approx. to about 0.2 of its length) and the setae on the upper head shorter (mostly shorter than the diameter of the anterior ocellus).
description: Published as part of <i>Liston, Andrew, Mutanen, Marko, Heidemaa, Mikk, Blank, Stephan M., Kiljunen, Niina, Taeger, Andreas, Viitasaari, Matti, Vikberg, Veli, Wutke, Saskia &amp; Prous, Marko, 2022, Taxonomy and nomenclature of some Fennoscandian Sawflies, with descriptions of two new species (Hymenoptera, Symphyta), pp. 151-218 in Deutsche Entomologische Zeitschrift 69 (2)</i> on page 151, DOI: 10.3897/dez.69.84080
description: {"references": ["Vikberg, V, 2017. Two sawflies new for the fauna of Russia, one being new for Europe and the western Palaearctic region (Hymenoptera: Symphyta: Heptamelidae and Tenthredinidae). Sahlbergia 23 (1): 17 - 19", "Malaise, R, 1931b. Entomologische Ergebnisse der schwedischen Kamtchatka Expedition 1920-1922. (35. Tenthredinidae). Arkiv foer Zoologi 23(2 [A8]): 1-68. [Separatum]", "Liston, AD, Vardal, H, Prous, M, 2018. New and poorly-known sawflies (Hymenoptera, Tenthredinoidea) from Sweden, with taxonomic notes on Palaearctic Heptamelus species described by Swedish authors. Entomologisk Tidskrift 139 (2): 119 - 131"]}