Holotype male (Fig. 1): USA, Connecticut, Tolland Co., Mansfield, Hunters Run, 41°46.18'N, 72°14.87' W, 4 July 2008, D. L. Wagner, mercury vapor light; DNA barcode voucher # CNCLEP 81920 (UCMS). Paratypes 54 males, 43 females. Connecticut: Litchfield County, Norfolk Great Mountain Forest, 13 July 1997, D. L. Wagner, (1 ♂) (UCMS) & 12 July 2008, D. L. Wagner, N. Proctor, A. Meleg (1 ♂) (UCMS); Middlesex County, East Haddam, Devil's Hopyard State Park, larvae 11 May 1994, 18 June, 1995, 20 June 1999, J. Fengler, J. Lozier, beaten from Tsuga canadensis (3 ♂) (CAES); New London County, Griswold, Hopeville Pond State Park, 9 July 1996, V. Giles (2 ♂) & 22 July 1997, F. Hohn (2 ♂) (UCMS); Tolland County, Mansfield, Hunters Run, 41°46'11"N, 72°14'52" W, 4–18 July 1997–2008, D. L. Wagner (3 ♂, 1 ♀) (UCMS); Windham County, Hampton, 2 July 1984, D. L. Wagner (1 ♂) (UCMS); Hampton Reservoir, NW of bog, 25–26 July 1996, D. L. Wagner & B. D. Williams (1 ♀) (UCMS); Catden Swamp, 25–26 July 1996, D. L. Wagner & B. D. Williams (1 ♀) (UCMS); Sterling Junction Rt. 14/14A, larva 30 June 2007, D. L. Wagner, beaten from and reared on Lonicera merrowii, emerged 18 July 2007, DLW Lot 2007F90.1 (1 ♀) (UCMS). Maine: Oxford County, Magalloway Plantation, State Route 16, 3 km NNE New Hampshire stateline, larva 5 June 1995, C. T. Maier, beaten from Abies balsamea (1 ♂) (CAES). Massachusetts: Franklin County, Montague Plain, 11 July 1991, D. L. Wagner, P. Z. Goldstein, & S. McKamey (1 ♂) (UCMS); Middlesex County, Concord, H.D. Thoreau's gravesite, 3–4 July 2009, D. L. Wagner (1 ♂) (UCMS). Michigan: Cheboygan Co., Pellston, Biological Douglas Lake, 7 July 2007, D. L. Wagner (1 ♂) (UCMS). New Jersey: Atlanta County, Egg Harbor Township, Absecon Creek, female 15 July 2002, D. F. Schweitzer, reared on dead oak leaves, emerged 13 Sept. 2002, DLW Lot 2002G117 (1 ♂) (UCMS); Atlantic County, Pomona, 6 July 1991, D. F. Schweitzer (1 ♂), gen. slide McCabe 2924 (TLM); Burlington County, Junction Route 563 & Wading River, 2 June 1999, D. L. Wagner, B. D. William, M. A. Volovski, & P. Mallard (1 ♂) (UCMS). New Hampshire: Coos County, Concord, 1 km NNE, North Concord, larva 4 June 1995, C. T. Maier, beaten from Abies balsamea, (1 ♂) (CAES); Pittsburg, Ildewide, west side of Second Connecticut Lake, larva 11 June 1996, C. T. Maier, beaten from Abies balsamea, JMF Lot 97–106 (1 ♂) (CAES). North Carolina: Haywood County, Cataloochee Campground, larva 10 June 2002, D. L. Wagner, beaten from Hamamelis virginiana, emerged 3 Aug. 2002, DLW Lot 2002E83 (1 ♀) (UCMS). New York: Albany Co., Pine Bush, 42°43.05' N, 73°52.16' W, 100 m, 2 July – 6 Aug. 1987–1997, T. McCabe (7 ♂, 3 ♀) (NYSM, TLM); Clinton Co., Gadway Barrens, 44°56.59'N, 73°45.17'W, 180 m, 2 Aug. 1997, T. McCabe (2 ♀) (TLM); Essex Co., Lake Stevens, 44°22.58'N, 73°54.15'W, 1055 m, 6 June 1986, T. McCabe (1 ♂) (TLM); Franklin Co., Bloomingdale bog, 44°24.36'N, 74°07.24'W, 475 m, 2 Aug. 1997, T. McCabe (4 ♀), gen. slide McCabe 4188 & 4186 (NYSM, TLM); Hamilton Co., 6 mi. E. Indian L, 43°45.44' N, 74°09.52' W, 555 m, 11 July–17 Aug. 1977–1980, T. McCabe (9 ♂, 6 ♀) (NYSM); Hamilton Co., 6 mi. E. Indian L, 43°45.44'N, 74°09.52'W, 555 m, 13 July 1977, T. McCabe (1 ♀, 1 ♂), gen. slide McCabe 1279 (NYSM); Orange Co., Cedar Pond bog, 44°56.59'N, 73°45.17'W, 180 m, 5 Aug. 2000, T. McCabe (1 ♂) (NYSM); Ulster Co., Lake Awosting, 41°42.43' N, 74°16.58' W, 550 m, 6 Aug. 1906, T. McCabe (1 ♀, 3 ♂) (NYSM); Ulster Co., Minnewaska St. Pk., 41°42.43'N, 74°16.58'W, 450 m, 6 Aug. 1906, T. McCabe (1 ♂) (NYSM). Québec: Val-Limoges, 200 km north of Ottawa, 46°39.8'N, 75°45.1'W, 14 July 2004, D. Handfield (2 ♀) (DH); La Présentation, 30 km east of Montréal, 45°41.3'N, 73°05.3'W, 30 June 2006, D. Handfield (2 ♂, 4 ♀) (DH); Sainte-Christine, 65 km east of Montréal, 45°39.0' N, 72°26.8' W, 3 July 2006, 20 July 2006, 28 July 2006, D. Handfield (2 ♂, 4 ♀) (DH); Villeroy, 175 km north-east of Montreal, 46°22.7' N, 71°49.9' W, 7 July 2006, D. Handfield (2 ♂) (DH); Saint-Narcisse, 200 km north-east of Montreal, 46°35.1' N, 73°11.9' W, 13 July 2006, D. Handfield (1 ♂, 2 ♀) (DH); Manseau, 150 km north-east of Montreal, 46°18.3'N, 72°00.7'W, 24 July 2006, D. Handfield (3 ♂, 9 ♀) (DH). Vermont: Essex County, Victory, Victory State Forest, 2.5 km SW Granby, larva 10 June 1997, C. T. Maier, on Abies balsamea (1 ♀) (CAES); Windham Co., Marlboro, Banks Road, 489 m, larva 15 June 1994, C. Lemmon, on Abies balsamea, Chris Maier Lot 94–89 (1 ♂, 1 ♀) (CAES).

The species name derives from the toothed antemedial and medial lines on the forewing.

Dark tooth-like spots along costa, marking beginning of antemedial and postmedial lines, distinguish Z. dentata from all but Zanclognatha lituralis, Zanclognatha martha, and some Zanclognatha protumnusalis. The presence of a third (subapical) costal spot, (where the subterminal line meets the costa), usually present in Zanclognatha lituralis, is absent in Zanclognatha dentata; the grayer ground color and uneven subterminal line also distinguish Zanclognatha lituralis from Zanclognatha dentata. Zanclognatha martha is distinguished from Zanclognatha dentata by its darker ground color, weakened subterminal line, darkened distal ¼ of forewing, and its larger size. The discal spot of Zanclognatha dentata tends to be larger, more vertically elongate, and the distal side is often more concave than that of Zanclognatha protumnusalis and others. The antemedial line of Zanclognatha dentata is more toothed (zigzagged) than that of most other similarly-sized, brown North American Zanclognatha (but see discussion). The postmedial line is often abruptly-angled outward over the radial veins in Zanclognatha dentata, whereas in Zanclognatha protumnusalis and Zanclognatha martha, this part of the postmedial tends to be more evenly rounded. In Zanclognatha protumnusalis the subterminal line is more likely to be outwardly edged with pale scales (in both wings) and Zanclognatha protumnusalis tends to have more tan in the ground color, thinner and crisper costal spots, and lacks the blurry patch of fuscous scales basad of the postmedial line, which extends from the inner margin to the cell, that is present in many Zanclognatha dentata. In most specimens of Zanclognatha protumnusalis the ground color of the hindwings tends to be noticeably paler than that of the forewings, especially through the radial area.

(Figs 5–7). Male genitalia of Zanclognatha dentata differ significantly from those of Zanclognatha lituralis – most notably Zanclognatha dentata has the upper process of the valve adorned with a small tooth, which is only half as long as the width of the costal lobe, whereas Zanclognatha lituralis has a large tooth that is as long as the costal lobe is wide. Zanclognatha lituralis has a valve that resists spreading during genitalic preparation and becomes badly skewed if forced. Zanclognatha martha resembles Zanclognatha dentata but is larger. The spread valves of Zanclognatha martha expand to 3.0 mm whereas those of Zanclognatha dentata expand to 2.7 mm. Zanclognatha dentata male genitalia appear indistinguishable from those of Z. protumnusalis to our eye. Female genitalia have similar internal spinules in the corpus bursa in Zanclognatha dentata, Zanclognatha lituralis, Zanclognatha martha, and Zanclognatha protumnusalis, but these extend farther on one side of the bursa in Zanclognatha protumnusalis and Zanclognatha dentata. In our dissections, length of the female genitalia in Zanclognatha dentata is ≥ 6 mm in total length, whereas those of Zanclognatha protumnusalis length measure circa 5 mm.

Male. Forewing length: FWL 10.5–13 mm (n=30). Head – pale to deep brown with forward projecting tufts from vertex. Antenna with male androconial notch at 1/3. Labial palpus with third segment 1/2 length of second, with pale scales at apex; second segment with pale scales over mesal surface. Thorax – dorsum concolorous with head. Forewing subtriangular, pale to chocolate brown, and usually well marked. Antemedial line toothed or scalloped; discal spot usually well developed sometimes with distal side concave; postmedial line toothed, thickened where it joins costa; often with diffuse medial patch of dark scales from inner margin to cell; subterminal line straight, sparsely edged outwardly with pale scales. Hindwing brown with weak discal spot and variously-developed postmedial and subterminal lines; the latter generally poorly differentiated to absent. If outwardly edged with pale scales, usually only over anal and cubital areas of wing. Underside of both wings usually with discal spot and well-expressed postmedial line. Procoxa elongate with yellow androconia. Profemur with (concealed) yellow hair pencil from distal end and fan of dark androconial scales from proximal end—both of which usually folded and covered by broad hood of chocolate colored scales from protibiae. Mesothoracic and metathoracic tibiae and tarsomeres lightened apically, appearing banded in dark individuals. Abdomen – Tan to brown with distal edge of each segment pale: abdomen appearing banded in well-marked individuals. Male genitalia (Figs 5, 6). Valves (Fig. 5) – Nearly symmetrical; uncus distally expanded compressed laterally, terminating in minute tooth; tegumen as long as valve; valve divided into two lobes for half its length; costal (upper) lobe with short mesal tooth halfway along length; costal lobe terminating in irregular apex crowned with setae, with apices of left and right valves differing in detail; lower lobe unadorned. Aedeagus (Fig. 6) – everted vesica covered with spinules; simple basal lobe; slightly curved mesal lobe; large distal lobe supports very small bulge without spicules. Female genitalia (Fig. 7) – Papillae anales unmodified, short; anterior and posterior apophyses subequal in length; distal half of ductus bursae lightly sclerotized, then heavily sclerotized and ribbed to beyond ductus seminalis; ductus seminalis short and twisted; caudal half of corpus bursae with relatively long, curved, internal spinules; spinules extend past middle of corpus bursae on side opposite ductus seminalis.

Dark, boldly-marked individuals are commonly encountered southward. In some, the medial patch of dark scales extends across the wing. Adult phenotypes overlap with those of Zanclognatha protumnusalis to the extent that we cannot reliably assign about 15% of light-trapped adults to one species or the other. No diagnostic genitalic characters are known for either sex. COI barcodes for those individuals that we could reliably identify were diagnostic (see below). The holotype was submitted to BOLD for COI barcoding (CNCLEP 81920) and its sequence will be submitted to GenBank. Larval features are also diagnostic (for both species).

So far as known, Ontario to Nova Scotia southward through the Great Lake states and in the Appalachians to northern Georgia. One moth from a sandhills area in central South Carolina appears to represent Zanclognatha dentata, but we excludethe moth from the type series.

Adults have been taken at lights and sugar bait from a broad range of habitats that includes bogs, swamps, marshes, Atlantic white cedar swamps, swales, and other wetlands, mesic hardwood and Appalachian cove forests, a variety of boreal (conifer) forest types, and pitch pine/scrub oak barrens. The species is essentially univoltine throughout most of its range with a single mid-summer flight from the end of June through early August, with more than 80% of the adults from New Jersey northward taken in July. Records from early September in western North Carolina and northern Georgia by James Adams (pers. comm.) are indicative of a small second brood, as also occurs in Zanclognatha protumnusalis and others (Wagner et al. 2011).

Chris Maier, Jeff Fengler, and Carol Lemmon, made numerous collections of Zanclognatha dentata during their survey of conifer-feeding caterpillars of the Northeastern United States (Maier et al. 2004). Nine of their larval collections were reared to the adult stage; larval images for four additional collections are assignable to Zanclognatha dentata. Their host records include: Abies balsamea (L.) Mill. (n=7), Tsuga canadensis (L.) Carrière (n=3), and Pseudotsuga menziesii (Mirb.) Franco. We have taken singleton larvae in beating sheet samples on three occasions: from Hamamelis virginiana L., Lonicera morrowii A. Gray, and a third, unrecorded host. All of the above were taken in May and June as penultimate or final instars. Although Zanclognatha species are generally regarded to be litter dwellers (Crumb 1956; Hohn and Wagner 2000; Wagner 2005), at least three other members of the genus (in addition to Zanclognatha dentata) are known to feed above the ground: Zanclognatha theralis (Walker, 1859) in Usnea lichens (Sigal 1984); Zanclognatha protumnusalis in fir, spruce, pines, and other conifers (Prentice 1962 and reared specimens in the PMNH); and Zanclognatha martha a hard pine associate (Wagner et al. 2011). We also have taken Zanclognatha cruralis (Guenée, 1854) and related species on occasion while beating low woody and herbaceous vegetation in forests, but mostly in the fall, before leaf fall, and not in the spring as has been the case with the four Zanclognatha listed above. Dale Schweitzer and DLW reared an ex ova cohort of Zanclognatha dentata through to maturity on a diet of dead oak leaves (DLW Lot 2002G117).