Trypophloeus borealis, Kvamme & Mandelshtam & Salnitska & Ojeda & Lindelöw & I., 2021

Kvamme, Torstein, Mandelshtam, Michail, Salnitska, Мaria, Ojeda, Dario I., Lindelöw, Åke & I., D., 2021, A new cryptic Trypophloeus Fairmaire, 1864 species in Northern Fennoscandia (Coleoptera, Curculionidae) revealed by DNA analyses, Norwegian Journal of Entomology 68, pp. 44-66 : 54-57

Trypophloeus borealis sp. n. (Figures: 5–9)

Examined material: Holotype: FINLAND: Male, Province of Enontekis Lappmark: Kuttanen , 68°26’N / 22°43’E, 4.VII.2012, leg/ det. Å. Lindelöw. The holotype will be deposited in Swedish Museum of Natural History (Stockholm, Sweden) SMNH . Paratypes: SWEDEN: 1 ex. Torne Lappmark, Årosjokk, 18.VI.1969, Lars Huggert leg., SMNH; 5exx., Torne Lappmark , Årosjokk. 67°87'N/19°37', 15.VI.2008, leg. et det. Å. Lindelöw, CÅL; 26 exx., Torne Lappmark , Årosjokk. 67°87'N/19°37' 5.VI.2009, leg. et det. Å. Lindelöw, CÅL; 1 ex. Torne Lappmark, Årosjokk, 67°52’ N, 19°22’E, stems of Salix myrsinifolia , 15.VI.2008, Å. Lindelöw leg./det., CÅL; 3 exx. Torne Lappmark, Akkar. 67°86'N/19°43', 5.VI.2009, leg. et det. Å. Lindelöw, ZIN; NORWAY: 8 exx., Region of Troms and Finmark, Karasjok : Jergul , 69°25’N / 24°58’E ( EIS 166 ), 3.VII.2012, stems of Salix myrsinifolia , leg./det. Å. Lindelöw, CÅL; 1 ex., Region of Troms and Finmark, Karasjok, Jergul, RT 90 7732/1858. 3.VII.2012. Svartvide. Leg et det. Å. Lindelöw, CTK; FINLAND: 8 exx., Province of Enontekis Lappmark: Kuttanen, 68°26’N / 22°43’E, 4.VII.2012, stems of Salix glauca (Ripvide) , 1-2 cm thick, leg. et det. Å. Lindelöw, CÅL; 1 ex. Province of Enontekis Lappmark : Kuttanen, 68°26’N / 22°43’E, 4.VII.2012, stems of Salix glauca (Ripvide) , 1-2 cm thick, leg./det. Å. Lindelöw, CTK.

Description. Body: 1.95–2.15 mm long. Head: frons convex, with densely and rather shallow, round, partially fusing punctures. Epistoma impressed, surface reticulated and shining; impression is divided into two parts by small median tubercle; epistomal impression have large fusing punctures.Vertex reticulated, not aciculated. Frontal surface with sparse inclined hair-like yellow setae; setae more abundant at epistomal margin. Eyes oval, with few facets missing behind antennal insertion. Antennae brown, only pedicel yellow. Pronotum: 1.1 times wider than long, with rounded posterolateral angles, broadly rounded; 4–8 denticles at anterior margin, arranged in concentric, transverse rows, highest pronotum point behind middle. Pronotum densely punctured near base and at posterolateral angles, brightly shining, faintly reticulated between punctures and evidently reticulated at flat bottoms of individual points; punctured area is covered by abundant and rather short hairs with their apices oriented forward and reaching the base of adjacent hairs. Anterior tuberculated part of pronotum with hairs directed backwards, with longer hairs at anterior margin of pronotum and at epipleura, surface between crenulations also reticulated but shining. Scutellum : flat and shining, strongly punctured, covered with short hairs which are oriented backwards. Elytra: more than 1.5 times as long as wide, 1.8 times longer than pronotum, with developed humeral angles; sides subparallel at basal 2/3 and rather narrowly rounded posteriorly. Surface brightly shining, glossy, with very faint reticulation and with strongly developed striae of round punctures, densely set, with less than 1/2 of puncture diameter between individual points, interstriae slightly wider than striae, with 3 irregular rows of minute punctures, each puncture bearing short hair-like scale directed backwards; central row of interstrial scales somehow longer, but still less than distance between individual bristles in row. Most of elytra has long, erect and thin hairs. Declivity with inclined hair-like scales, rather gradual, occupying only posterior 1/3 of elytral length, with suture not elevated. Individual inclined scales at elytral declivity are strongly serrate at sides and are pointed at apex, recumbent scales at declivity are also strongly serrate. Legs: femur and tibia brown and tarsus are yellowish.

A small 8 th abdominal tergum is present in males, but not females. This is a common feature of all former Cryphalini , including Trypophloeini .

Diagnosis. Specimens of T. borealis sp. n. from Northern Fennoscandia differs morphologically only subtly from T. nitidus and T. dejevi . T. borealis sp. n. differs from T. nitidus by slightly larger size (1.67–2.25 mm vs. 1.7–1.9 mm in T. nitidus ). The average length of T. borealis sp. n. was 2,03 mm. In long series of “ nitidus / striatulus ” (at BEM) body length was found to be 1.6–2.1 mm). The structure of the frons, which is usually medially impressed in T. nitidus , can be very variable.

Etymology. The name borealis is a derivation of boreal, which means “belonging to the north”.

Notes on the biology and development of Trypophloeus borealis sp. n.

Biology and development in T. borealis are very similar to T. nitidulus in North America ( Furniss 2004, 2013), except different host tree choice. Newly emerged adults perform maturation feeding in cave-like galleries in the bark of living trees/ bushes of Salix . After hibernation, some adults may leave the host tree and disperse. Suitable trees are colonised for reproduction. In some cases, this may occur in the same gallery in which hibernation took place. Colonisation seems to be related to parts of the tree, which have reduced vitality or damaged or dying tissue. Galleries have been found in the transition zones between dead and alive tissue. Such zones often occur after cracks and other damages caused by snow during the winter. T. nitidus mating is taking place at the bark surface. The female enters the bark first, joined by the male later. The Trypophloeus species are monogamous and only one female and one male are found in a gallery. The eggs are laid in a cluster ( Furniss 2004) in the gallery. Thus, the female does not make a separate niche for each egg. This behaviour is characteristic in Cryphalinii ( Wood 1982). The development seems to be irregular. In mid-June parent beetles and larvae were found together in the galleries and in early July, adults, pupae and larvae have been observed ( Lindelöw and Kvamme 2013). We assume that the development time can be more than one year due to the short summers and harsh climate in the North. Since galleries can be found in small parts of trees it is likely that the species can develop for several generations in the same trunk when the area of dead tissue increases year by year.

The first Scandinavian record was probably made by sweeping in June in the area where the species was rediscovered in Salix myrsinifolia ( Lindelöw 2009) . In Norway the host tree was also S. myrsinifolia . In Finland the species was found in 1–2 cm thick trunks of Salix glauca ( Lindelöw and Kvamme 2013) . S. myrsinifolia (= S. nigricans ) is widely distributed in North Europe, eastwards to the Ob Valley. S. glauca is circumpolar and widely distributed, both in Palaearctic as well as Nearctic ( Hultén & Fries 1986, Jonsell 2000).

Orange tendrils of fungus protruded from the bark surface have been observed several times (Figure 16) ( Lindelöw and Kvamme 2013). They resemble the Cytospora sp. that Furniss (2004) observed on the bark surface of Salix alaxensis (Andersson) , which was colonised by T. nitidus . Any possible relation between the fungus and the beetles is unknown. Spores found on the surface of the pronotum of T. striatulus did not belong to Cytospora sp. ( Furniss 2004).