Heptamelus viitasaarii Liston, Mutanen & Prous, 2022

Liston, Andrew, Mutanen, Marko, Heidemaa, Mikk, Blank, Stephan M., Kiljunen, Niina, Taeger, Andreas, Viitasaari, Matti, Vikberg, Veli, Wutke, Saskia & Prous, Marko, 2022, Taxonomy and nomenclature of some Fennoscandian Sawflies, with descriptions of two new species (Hymenoptera, Symphyta), Deutsche Entomologische Zeitschrift 69 (2), pp. 151-218 : 151

publication ID

https://dx.doi.org/10.3897/dez.69.84080

publication LSID

lsid:zoobank.org:pub:3B245B53-7156-4A3F-9667-2F2CD756779A

DOI

https://doi.org/10.5281/zenodo.7019619

persistent identifier

https://treatment.plazi.org/id/9AEF81A4-3C92-430D-83E0-8EC11EEFF14E

taxon LSID

lsid:zoobank.org:act:9AEF81A4-3C92-430D-83E0-8EC11EEFF14E

treatment provided by

Deutsche Entomologische Zeitschrift by Pensoft

scientific name

Heptamelus viitasaarii Liston, Mutanen & Prous
status

sp. nov.

Heptamelus viitasaarii Liston, Mutanen & Prous sp. nov.

Description.

Female. Figs 23 View Figure 23 , 24A-C View Figure 24 , 26A, B View Figure 26

Colour. Fig. 26A, B View Figure 26 . 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 View Figure 23 ), 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.

Head. Pedicel about as long as scape. Head in lateral view with widest point on temple about equal to length of pedicel (Fig. 23E View Figure 23 ). 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 View Figure 23 ). Clypeus densely pitted, weakly shiny; anterior margin widely emarginate, to about 0.4 of its length (Fig. 23D View Figure 23 ). Setae on upper head as long, or longer than, diameter of anterior ocellus (Fig. 23E View Figure 23 ).

Thorax. Whole pronotum except for small antero-ventral area dull, with sculpture (Fig. 23H View Figure 23 ). Pits on upper mesepisternum large and well-defined (Fig. 23H View Figure 23 ). Mesoscutellum with large, scattered pits anteriorly and laterally, interspaces shiny; medially and posteriorly nearly without pits and entirely unsculptured (Fig. 23F View Figure 23 ). Anterior of mesoscutellar appendage densely pitted, with numerous setae, only small posterior area unpitted (Fig. 23F View Figure 23 ).

Abdomen. 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 View Figure 24 ). In lateral view exposed length of cercus about 0.5 × as long as exposed upper length of valvula 3 (Fig. 23G View Figure 23 ). Lancet (Fig. 24B, C View Figure 24 ): 13-14 serrulae; apical serrulae short and high.

Body length: 4.5-8.0 mm

Male. Figs 24D View Figure 24 , 26C View Figure 26

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 View Figure 24 .

Body length: 4.5-5.5 mm

Variability: 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.

Holotype ♀ (ZMUO.044130). Type locality: Finland, Karelia borealis, Kitee Otravaara, YKJ grid coordinates: 6868:3663 [61.8877N 30.1096E]; 04.08.2019 [larva] in Athyrium filix-femina (L.), Rearing 380/2019, leg. M. Mutanen. Labels white, printed, except for red holotype label. Deposited in the ZMUO.

Paratypes. Total: 92♀, 6♂. Finland [leg. M. Mutanen and in ZMUO unless otherwise stated]:

Karelia borealis, Kitee: Otravaara [Type locality]; 17♀ (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 Athyrium filix-femina (L.), Rearing 380/2019. 7♀ (including ZMUO.034957, ZMUO.034958, ZMUO.034959), Otravaara, YKJ grid coordinates: 6868:3663 [61.888°N, 30.110°E], 19.06.2018. 30♀ (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: Athyrium filix-femina , rearing 174/2020. 1♀ (ZMUO.046037), 15.06.2020. ZMUO and SDEI. Otravaara, YKJ grid coordinates: 6868:3664 [61.887°N, 30.129°E]; 8♀ (including ZMUO.034859, ZMUO.034860), 19.06.2018. 1♀ (ZMUO.034995), 18.06.2018. Pajarinmäki, YKJ grid coordinates: 68899:36670 [62.078°N, 30.197°E]; 1♀ (ZMUO.032885), at light, 11.07.2017 [end date of about 5-day period]. 1♀ (ZMUO.033391), at light, 18.07.2017 [end date of about 7-day period]. 2♀ (including ZMUO.034899), 20.06.2018. 1♂ (ZMUO.061917), 14.06.2021, leg. A. Liston, M. Mutanen, M. Prous. 1♂ (ZMUO.061893), 15.06.2021, leg. N. Kiljunen, A. Liston, M. Mutanen, M. Prous. 4♂ 8 ♀♀ (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 Matteuccia struthiopteris (L.) (ZMUO.060557, ZMUO.060558) and 2 larvae from Athyrium filix-femina (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♀ (including ZMUO.034761, ZMUO.034762), 18.06.2018, ZMUO and SDEI. 1♀ (ZMUO.040497), 12.06.2019. Puhos, YKJ grid coordinates: 6889:3653 [62.080°N, 29.938°E]; 2♀ (including ZMUO.034968), 20.06.2018. Hiidensaari, YKJ grid coordinates: 6891:3668 [62.092°N, 30.226°E]; 1♀ (ZMUO.034908), 20.06.2018. Potoskavaara, YKJ grid coordinates: 6893:3670 [62.109°N, 30.266°E]; 1♀ (ZMUO.046430), 28.06.2020, leg. Tupu Vuorinen. Satulavaara, YKJ grid coordinates: 6877:3672 [61.964°N, 30.289°E]; 3♀ (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♀ (ZMUO.058146), 16.06.2021, leg. A. Liston, M. Mutanen, N. Kiljunen, M. Prous. Joutseno Kuurmanpohja Sunninmäki [61.071°N, 28.731°E]; 1♀ (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♀ (ZMUO.061964), 08.06.2021.

Other material.

Finland: Nylandia, Vantaa , YKJ grid coordinates: 669:37, 17.06.2021, 1♀, leg. Miikka Friman.

Etymology.

Named after Matti Viitasaari, who first recognised a very large female of this species as probably not belonging to Heptamelus ochroleucus or H. dahlbomi .

Habitat.

Damp, shady places in woodland.

Biology.

Many female specimens have been reared from larvae in Athyrium filix-femina (L.) Roth. (Fig. 25 View Figure 25 ). Larvae found abundantly in 2021 in Matteucia struthiopteris (L.) Tod. in Kitee, Finland, were provisionally identified as H. viitasaarii 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 View Figure 25 ). This results internally in a “ladder-like” appearance, which is externally clearly visible, especially against the light (Fig. 25A View Figure 25 ). This feeding habit is, however, possibly widespread in Heptamelus : at least H. dahlbomi larvae feed in the same way. Larvae of H. viitasaarii in M. struthiopteris 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 Heptamelus ochroleucus .

Differential diagnosis.

The characters which are most useful for the identification of European Heptamelus species are presented below in a key. The extensively pitted and setose mesoscutellar appendage distinguishes H. viitasaarii from the two other European species, as well as H. magnocularis Malaise, 1931 ( Malaise 1931b) from the Russian Far East (see Liston et al. 2018). Note that all body parts of H. viitasaarii are conspicuously more densely setose, and pitted, than most other Heptamelus species which we have so far examined.

From the females of Heptamelus dahlbomi , H. ochroleucus , H. magnocularis , H. montanus Togashi, 1961, and H. takeuchii Togashi, 1961 (the latter two from Japan), H. viitasaarii differs in its much shorter and higher apical serrulae of the lancet (Fig. 24A, B View Figure 24 ). Heptamelus viitasaarii has a wider sawsheath in dorsal view than either H. dahlbomi or H. ochroleucus . Heptamelus japonicus Togashi, 1961, only known in the male sex, differs from H. viitasaarii in its entirely pale thorax, abdomen and fore wing pterostigma. The male of H. takeuchii differs from H. viitasaarii in its more shallowly emarginate and smoother clypeus, and the pale abdominal sternum 9. The male of H. montanus resembles that of H. viitasaarii in coloration, but as in females of these species, the clypeus of H. montanus 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).