Acossus boreocryptus Schmidt & Jaeger, 2024

Schmidt, B. Christian & Jaeger, Christi M., 2024, A new species of Acossus Dyar (Lepidoptera: Cossidae) establishes diurnal flight in New World carpenter-moths, Canadian Journal of Zoology 102 (11), pp. 871-879 : 873-877

Acossus boreocryptus Schmidt & Jaeger n. sp.

urn:lsid:zoobank.org:act:B04C10AC-70FB-40D4-BB24-9DD3E65D1290

Figs. 2 , 4 , 6 , and 9

♂ ♀

TYPE MATERIAL: Holotype. ♂ [ CNC]. Canada, Ontario, Ottawa, 5 km NE Almonte, Burnt Lands Rd. , 45.266 ◦ N 76.147 ◦ W, 11– 14 June 2022, B.C. Schmidt & C.M. Jaeger, UniTrap baited with E,E- TDDA pheromone. Voucher # CNCLEP00321999 . Paratypes. 80♂ 3♀ [ CNC]. Ontario. Ottawa, 5 km NE Almonte, Burnt Lands Rd. , 45.266 ◦ N 76.147 ◦ W, 11–17 June 2022, B.C. Schmidt & C.M. Jaeger, pheromone/UniTrap, 42♂; Ottawa, 3 km NE Almonte, Golden Line Rd. , 45.250 ◦ N 76.147 ◦ W, 14 June 2022, B.C. Schmidt & C.M. Jaeger, pheromone/UniTrap, 11♂; Ottawa, 6.5 km NE Almonte, Upper Dwyer Hill Rd. , 45.259 ◦ N 76.116 ◦ W, 14–27 June 2022, B.C. Schmidt & C.M. Jaeger, pheromone/UniTrap, 4♂; Ottawa, HowieRd. extension, 45.250 ◦ N 76.039 ◦ W, 16June2011, B.C. Schmidt, UV light, 1♀; Timiskaming District, Markle Lake , 47.933 ◦ N 80.510 ◦ W, 17 June 2023, B.C. Schmidt & C.M. Jaeger, pheromone/UniTrap, 11♂; Cochrane District, Otter Rapids Rd. , 50.065 ◦ N 81.565 ◦ W, 21 June 2023, B.C. Schmidt & C.M. Jaeger, pheromone/UniTrap, 12♂. Quebec. Gatineau, Luskville Falls picnic area , 45.533 ◦ N 75.996 ◦ W, 10 June 2005, J.F.Landry,DNAsampleID:jflandry 2948,1♀. NewBrunswick. York Co., Hanwell, 45.903 ◦ N 66.752 ◦ W 04 July 2013, G. Hensel, DNA sample ID: CNCLEP00298974 , 1♀.

ADDITIONAL MATERIAL EXAMINED: Alberta. Calgary, Head of Pine Creek, 18 July 1002, F.H.W. Dod [ CNC]; Fort McMurray , 12 June 1953 [ CNC]; North Dakota. Bottineau Co., Section T63 , Range 76, 19 June 1978, A.D.Tagestad [ USNM] Ontario. Marmora , 15 June 1953 [ CNC]; Manitoulin Is. , Pike Lake, S end, 8July2003, J.Morton [ CNC]; VermillionBay, CedarLake , 12 July 1963, R. J. Acheson [ CNC] Quebec. Saint-Maurice, Parc delaMauricie, Sect.Passage , 23June2006, D.Handfield [ CNC] Saskatchewan. Indian Head , 1 June 1937, C. R. Douglas [ CNC]; Indian Head , reared ex larva from aspen, emerged 26 June 1941, L.O. T. Peterson, voucher # NFRC-2021-20047 [ NOFC].

ETYMOLOGY: Boreocryptus is a contraction of boreus (northern) and crypticus (hidden). The common name Lesser Poplar Carpenter-moth is proposed here to distinguish it from Poplar Carpenter-moth ( A. centerensis ).

DIAGNOSIS: Acossus boreocryptus ismostsimilarto A. centerensis . These two closely related species can be separated from the Acossus populi group (the remainder of North American Acossus ) by the finer, more striate forewing pattern compared to the more irregular, reticulate pattern of the populi -group; the darker basal half of the forewing compared to the distal half (ground color evenly grey in the populi -group); and the hyaline hindwing, which is more opaque in the populi -group.

The most obvious differences between boreocryptus and centerensis arethesmallersize(30%–40%smallerthan A. centerensis ), the greater translucence of the outer third of the male forewing, the slightly more diffuse black reticulate markings of the forewing, and the paler, more contrasting posterior margin of the thorax ( Figs. 1 and 2 ). In live specimens and non-greasy museum specimens, the tegulae, patagia and posterior margin of the thorax are all conspicuously paler in A. boreocryptus , resulting in a more contrasting dark/pale thoracic pattern. Females of the two species are more difficult to separate, since A. boreocryptus females do not have pronouncedly translucent forewings like the males (the pale forewing scales are apparently not deciduous as they are in males). Smaller size and the less crisply marked reticulate pattern are the best clues. Under magnification, it is apparentthat A. boreocryptus have smaller,sparserwhite-greyscales on the distal third of the forewing, and that most of these are apparently shed or lost (the black scales are retained); in A. centerensis males, the distal third of the forewing is more denselyscaled,andtheblackscalesareonaveragelargerand more elongate-triangular ( Figs. 3 and 4 ). The male forewing lengthof A. boreocryptus islessthan 19mm (average 16.5mm), versus19mmormorein A. centerensis ;small,stunted centerensis males with wing lengths under 19 mm can occur, but are rare (2 out of 136 specimens examined). The flight period of A. boreocryptus commences and peaks about 10 days earlier than that of A. centerensis , with overlap during the end of the boreocryptus flight and the beginning of the centerensis flight, usually in late June to early July. No consistent differences in male or female genitalic structure compared to A. centerensis were noted ( Figs. 5–8 ).

DESCRIPTION:Head——vestitureoffrons,vertexandbaseofantennathickandlightgrey;dorsumofantennawithlightgrey scales; male antenna short-plumose with longest rami 3.3× longer than segment length; female antenna filiform; eyes fully developed and hemispherical, similar in size and morphologyto A. centerensis .Thorax——dorsumofthoraxwithdark grey to grey-black vestiture, posterior margin with conspicuous contrasting pale whitish-grey transverse band; patagium and tegula pale grey; patagia medially often shaded darker grey, resulting in slightly darker grey medio-anterior thoracic shading; ventrum of thorax with thick, loose vestiture of mouse-grey, long spatulate scales, interspersed with pale greyscales;legswithappressed,dark-greyscales,theanterior end of tarsal segments ringed in paler grey. Forewing——mean forewing length 16.5 mm in males (14.3–18.4 mm; n = 14), 21.8 mm (19.9–23.9 mm; n = 5) in females; entire forewing coveredwithanirregular,finelystriateblackpattern;pattern details are highly variable, but often a transverse line in the medial and postmedial position is discernible; basal half of forewing with dark grey-black ground color, outer half with dull ivory white scales, these usually lost towards outer margin of wing and apparently deciduous; when present, these whitish scales are noticeably smaller than black scales; ventrumofforewingwithstriatepatternmoremuted,anddiscal area with dense, long scales; fringe alternatingly black and pale grey, the dark portions centered on the vein termini. Hindwing——basal third and anal marginal band with dense black hairlike scales, the remainder of the wing devoid of scales and translucent; fringe striped in light grey and black; ventrally with striate pattern somewhat pronounced at the base of the costal margin. Abdomen——dorsally and ventrally with a thick, even mouse-grey vestiture, interspersed with pale grey scales. Male genitalia ( Fig. 6 )——valvae quite immobile relative to tegumen, such that it is not easy to spread them without distorting the entire genital capsule; valve rounded triangular and heavily cupped, with a ridge-like apex; clasper a long evenly curved tine extending from basal marginandcurvingacrosstoventralmarginofvalve;clasper densely and finely spiculose; uncus short and U-shaped with a broad base and rounded apex; gnathos finely and densely spinulose; aedaegus approximately 10× longer than wide; vesica a simple elongate sack. Female genitalia ( Fig. 8 )——overallmorphologyverysimilartoother Acossus species,with ovipositor very long and telescopic; papillae anales setose, narrowwithrounded-acuteterminus;posteriorapophysisextremely long, length approximately equal to 4× width of ostial plate; anterior apophysis approximately 2× width of ostial plate; ostium small and inconspicuous; ostial plate consisting of two shallow cup-like depressions anterior to ostium; large membranous sac anterior and ventrad of ostial plate,comprising2–3internalmembranes,ofunknownfunction;ductusbursaemoderatelysclerotized,straightandtubular, slightly flattened, 6× longer than wide; corpus bursae a simple capsule-shaped sac, lacking signa; ductus seminalis originating right dorso-laterad.

BIOLOGY: Adult males of A. boreocryptus appear to be entirely diurnal ( Fig. 9 ), whereas females have been captured using light traps. Efforts to capture adults by light trap concurrent withpheromonetrappingyieldedneithermalesnorfemales, althoughmaleswerecommonatpheromoneluresduringthe day (sites 6 and 7; Table 1 ). Extensive surveying of the moth fauna in eastern Ontario using light traps has yielded only a single female of A. boreocryptus , indicating that females are only rarely attracted to light. There is also a paucity of male specimens in historic collections, only two males were discovered among A. centerensis holdings. This may reflect diel activity patterns inherent in some other mostly diurnal Lepidoptera , such as dispersal or oviposition flights by females that occur at dusk or into the evening, while courtship and matingislargelyrestrictedtotheday.IneasternOntario,the adult flight period commences in early June, with peak activity in mid June and tapering off into early July ( Fig. 10 ). More northerly, boreal populations fly later, since males were still fresh and common in late June (site 6, Table 1 ).

The biology of the immature stages remains largely unknown,althoughsomeliteratureaccountsof A. centerensis larvae in Populus tremuloides Michx. may actually refer to A. boreocryptus . Solomon (1995) gives a detailed summary of the natural history of A. centerensis . A single specimen reared from P. tremuloides (Indian Head, Saskatchewan; NOFC voucher # NFRC-2021-20047) is the only confirmed larval host plant record. At two study sites where both A. boreocryptus and A. centerensis were common (sites 1 and 2, Table 1 ), P. tremuloides was the only species of Populus common enough to accommodate the abundance of Acossus . Lintner (1877) gives a detailed account of finding adults and pupae of centerensis on P. tremuloides near Albany, NY, and the type specimens of his centerensis ( Fig. 1 c ) are unquestionably not the species here describedas A. boreocryptus . Acossus centerensis larvaehavealso been recorded from Populus balsamifera L. in the study area ( Fletcher 1883). Both species can occur in strict sympatry as evidencedinthisstudy,suggestingthatbothmayuse P. tremuloides as a larval host, and raising the interesting possibility that larval habitats are partitioned into different niches such as different parts, sizes, or ages of trees.

COI BARCODE VARIATION: DNA barcodes of A. boreocryptus (n = 4) shared a single haplotype, and were assigned to BIN# BOLD:AAC4784. The nearest-neighbour haplotypes are assigned to A. centerensis , and differed by a minimum of 5.13%. (BIN # BOLD:AAB5740). Comparison of A. boreocryptus barcode sequence to others in the BOLD database revealed identical haplotypes of two additional samples corresponding to voucher specimens from a previous pheromone study by Dix and Doolittle (1985). In that study, a bimodal flight phenology of A. “ centerensis ” in South Dakota was noted. Although this phenology pattern was attributed to intraspecific variation of A. centerensis , it is now clear that two species were sampled: A. centerensis , and the smaller, earlier-flying entity A. boreocryptus . This underscores the critical importance of vouchering specimens in ecological studies, as it is now possible to link revised taxonomies and a fundamentally different interpretation of results for a study conducted 43 years ago.

DISTRIBUTION: Acossus boreocryptus occurs at least from south-centralNewBrunswickwestthroughnorthernNorthDakota to southern Alberta. All known occurrences are well within the geographic range of P. tremuloides ( Fryer 2018) . The oldest known specimen of A. boreocryptus is a historical specimen collected in 1902 by F.H. Wolley Dod near his homestead in the foothills southwest of Calgary. Although Dod’s collecting efforts were extensive, it is the only specimen he recorded( Dod1906;specimeninCNC),amalecollectedon 18 July 1902. Interestingly, James Fletcher, one of the forebears of Canadian entomology, questioned Dyar’s identification of Dod’s specimen as A. centerensis , stating that “It looks too clean [to be centerensis ]” ( Dod 1906). The existence of A. boreocryptus was also hinted at nearly 40 years ago, when Dix and Doolittle(1985) notedabimodalphenologyinpheromonetrials of A. centerensis .

The northern range extent of A. boreocryptus is currently the edge of the James Bay lowlands in northern Ontario ( Fig. 11 ). Although records are lacking for many intervening regions,includingManitoba, Minnesota, Wisconsin,andMichigan, occurrence of boreocryptus in a wide range of ecoregions from aspen parkland to northern boreal mixedwood forest suggests that it likely occurs widely across the central and southern boreal forest. It is possible that A. boreocryptus has a morerestrictedrangethan A. centerensis ( Fig.11 ),butdirected surveys for this easily overlooked species are still needed in most parts of the continent.

Figures

Figs. 1–2. Adult Acossus. 1a Poplar Carpenter-moth (Acossus centerensis) ♂, Burnt Lands Rd., Ottawa district, Ontario; 1b Poplar Carpenter-moth(Acossus centerensis) ♀,Edmunston,NewBrunswick; 1c.Cossus centerensis LintnerLECTOTYPEandoriginallabels; 2a LesserPoplarCarpenter-moth(Acossus boreocryptus) ♂,HOLOTYPE,BurntLandsRd.,Ottawadistrict,Ontario; 2b LesserPoplar Carpenter-moth (Acossus boreocryptus) ♀, PARATYPE, Hanwell, New Brunswick, DNA barcode voucher # CNCLEP00298974.

Fig. 4. Postmedial portion of left forewing of Lesser Poplar Carpenter-moth (Acossus boreocryptus). Note smaller black scales and sparser scale arrangement compared to Poplar Carpenter-moth (Acossus centerensis) (Fig. 4a).

Figs. 5–6. Male genitalia of Poplar Carpenter-moth Acossus centerensis (5) and Lesser Poplar Carpenter-moth Acossus boreocryptus (6). Valvae (va) and juxta (jx) have been disarticulated from the genital capsule for visual clarity; phallus (ph) with inflatedvesicaorientedtotherightandventralsurfacefacing downwards (c).

Fig. 3. Postmedial portion of left forewing of Poplar Carpenter-moth Acossus centerensis. Note larger black scales and denser scale arrangement compared to Lesser Poplar Carpenter-moth (Acossus boreocryptus) (Fig. 4b).

Figs. 7–8. Female genitalia of Poplar Carpenter-moth, Acossus centerensis (7) and Lesser Poplar Carpenter-moth, Acossus boreocryptus (8),ostiumindicatedas(os)andantevaginalplate (avp).

Fig. 9. Adult male Lesser Poplar Carpenter-moth (Acossus boreocryptus) approaching UniTrap baited with synthetic pheromone. Markle Lake peatlands, Ontario, 18 June 2023.

Fig. 10. Abundancesummaryofmale Acossus capturedatSite 1usingsyntheticpheromonelures,between9Juneand6July 2022. Black = Acossus boreocryptus, grey = Acossus centerensis.

Fig. 11. Distribution of examined voucher material for Lesser Poplar Carpenter-moth, Acossus boreocryptus (red), and Poplar Carpenter-moth, Acossus centerensis (yellow). Created using SimpleMappr (https://www.simplemappr.net/). Base map in Public Domain, North America Lambert Projection.