Holotype ♂ (FMNH): “USA: VA: Bath Co., 38.0744°N, 79.6836°W, Dry Run Gorge, X.28.2018, C. Harden, oak-hickory woods; limestone gorge.” / “CLEMSON ENT [QR CODE] CUAC000185176”. Paratypes (3, CUAC, FMNH, VMNH): same data as holotype (CUAC000185174, CUAC000185175, CUAC000185177).

Virginia: same data as holotype, CUAC000187891 (1 larva, CUAC); Highland Co.: Owl Cave, 2070’, Water Sinks (38.2205, -79.6046), C. Harden, 31 May–2 Aug 2019 (CUAC); Highland Co.: Water Sinks, 2080’ (38.2211, -79.6042), C. Harden, 4 May–31 May 2019 (VMNH).

This species is larger than most microphthalmous Lathrobium known from Virginia and West Virginia. Males can be distinguished from most species by the lack of setal combs on sternite VIII and females by the presence of gonocoxite lobes. Lathrobium solum is of similar size and also lacks the transverse combs on sternite VIII. However, Lathrobium solum has transverse antennomeres V–VII, and more widely separated gular sutures. Aedeagi differ in the shape of their major spines, and L. solum has a characteristically shaped ventral process that reaches the dorsal plate in lateral view. The female of L. solum is unknown, so no distinctions can be made.

Habitus (Fig. 11A). Large species, total body length ~ 9 mm long, FL 3.4–4.0 mm long. Coloration: body and appendages pale reddish.

Head slightly wider than long, widest at posterior; posterior angles rounded. Epicranium coarsely punctate with punctures less dense in median dorsal portion; interstices with strong transversely reticulate microsculpture throughout; head setose throughout, with long macrosetae projecting at posterior corners of head, corners of eyes, laterally posterior to eyes, and above mandible insertions; gular sutures (sulci) narrowing posteriorly until nearly touching; neck 1/2 as wide as head. Eyes reduced to small white membranes without ommatidia, occupying 1/9 length of head. Antennae moniliform, as long as head and pronotum combined; scape as long as antennomeres II and III combined; antennomeres II–IX obconic, longer than wide but become progressively wider; apical antennomere longer, subacute.

Pronotum longer than wide, narrower than head and elytra; widest at anterior angles and tapering slightly posteriorly; all angles round, posterior angles less so; punctation is dense, punctures spaced one diameter apart, impunctate at midline with a faint line visible on posterior two thirds; interstices shiny with no microsculpture. Elytra distinctly shorter than pronotum, as wide as head, approximately as long as wide; posterior margin sinuate; punctures small and shallow with indistinct edges, irregularly spaced, most one diameter apart; setae angled to posterior; interstices with finely punctate microsculpture. Hindwings vestigial. Posterior margin of abdominal tergite VII without palisade fringe.

Figure 11. 

Lathrobium absconditum A habitus B female terminalia C female sternite VIII D male sternite VIII E aedeagus in ventral view F aedeagus in lateral view. Scale bars: 1 mm.

♂: Larger, forebody 3.8–4.0 mm. Posterior margin of sternite VIII with broad but shallow emargination, patch of dense setae medially (Fig. 11D). Aedeagus 1.5 mm long; ventral process long, narrow, and asymmetrical (Fig. 11E, F); dorsal plate short and broad; internal sac with five spines, major spine long with two narrow asymmetrical processes.

Figure 12. 

Lathrobium absconditum second instar larva A habitus B nasale C mandible D maxilla E antenna. Scale bars: 1 mm (A, C); 500 μm (B, D, E).

♀: Smaller, forebody 3.4 mm. Sternite VIII oblong, apex notched with micropubescence (Fig. 11C); paraprocts undivided anteriorly, apices longer than basal portion; proctiger conical; sternum IX with coxites and valvifers fused (Fig. 11B), base produced into distinct setose lobes; subgenital plate absent.

Second instar larva : Body elongate, ~ 7 mm long; lightly sclerotized (Fig. 12A), head more sclerotized; head and thoracic tergites light brown, legs and body white, translucent.

Head ovate, tapered posteriad (in dorsal view), dorsoventrally flattened, 1.3× as long as wide, with dorsal setae as in Fig. 12A; head 3.6× wider than neck; dorsal ecdysial lines bifurcate 2/5 distance between neck and nasale margin; stemmata absent; anterior margin of nasale (Fig. 12B) as in L. hardeni, but median tooth triangular with edge serrated; Apotome of gula not reaching tentorial pits.

Antennae (Fig. 12E) length ratios: 1.0:3.8:2.9:1.7; antennomere I triangular; antennomere II with two pores; antennomere III with three elongate macrosetae, three solenidia, one pore; antennomere IV club-shaped with apical solenidia; sensory appendage 0.8× as long as antennomere IV.

Mandibles (Fig. 12C) long, falciform, serrate along apical 1/3 of inner margin, with a single seta near base on outer ventral edge. Maxilla (Fig. 12D) with cardo triangular; stipes elongate, 1.7× longer than cardo; mala digitiform, tapering toward apex, 0.9× as long as palpomere I, with apical sensory appendages and two pores; palpifer with one seta. Maxilla and labium as in L. hardeni, except maxillary palpomere length ratios: 1.0:1.4:2.7; ligula separated from prementum by a distinctly sclerotized transverse strip; palpomere I 1.2× as long as II; palpomere II bent near apex.

Dorsal sclerites of thorax with ecdysial lines along midline; prothorax narrow, 1.1× as long as wide, narrowed anteriorly, chaetotaxy as in Fig. 12A; thoracic tergite II longer than tergite III; abdominal sclerites lightly sclerotized, with two small pleural sclerites per segment on each side; basal segment of urogomphus 4× as long as terminal segment, with seven prominent lateral setae; terminal segment of urogomphus slender, with one short and one long apical seta.

The specific name is Latin (singular, neuter), meaning hidden or concealed, in reference to the species’ endogean habitat.

Lathrobium absconditum is known from Highlands County and Bath County, Virginia (Fig. 13). Two specimens were collected near the mouth of Owl Cave, but none were found inside the cave. All specimens were collected with buried pipe traps, which suggests they are hypogean. Adults collected Mar–Oct. Larvae collected in Oct. Males and females have yet to be collected together.

Larvae were associated with adults by DNA barcoding.

Holotype ♂ (FMNH): “USA: NC: Haywood Co., 35.3632°N, 82.9885°W, Richland Balsam Mountain, 6180’, IX.11.2019, Sifted Litter, M. Caterino.” / Caterino DNA voucher, Ext. MSC-4413, Morphosp RB.B.320” / “CLEMSON ENT [QR CODE] CUAC000003949”. Paratypes (4, CUAC, FMNH): 2: same locality as type, 35.3627°N, 82.9885°W, IX.11.2019 (CUAC000003627, CUAC000177150); same locality as type, 35.3630°N, 82.9890°W, 6200ft, v.08.2018 (CUAC000177151); same locality as type, 35.3676, -82.9902, 6398’, v.8.2018 (CUAC000048512).

Figure 13. 

Distribution of Lathrobium absconditum (triangle), L. balsamense (square), L. hardeni (star), L. smokiense (circle).

North Carolina: Jackson Co.: Balsam Mountain Preserve, Nantahala National Forest, (35.3751, -83.0981), S. Myers, 15 Jun 2015 (CUAC); Haywood Co.: Mt. Lyn Lowry, 6205’ (35.4640, -83.1100), M.S. Caterino, 22 Sep 2020 (2, CUAC); Haywood Co.: Mt. Lyn Lowry, 6192–6203’ (35.4640, -83.1101), M.S. Caterino, 15 Apr 2021 (9, CUAC); Haywood Co.: Mt. Lyn Lowry, 6200’ (35.4638, -83.1108), M.S. Caterino, 22 Apr 2020 (3, CUAC); Haywood Co.: Richland Balsam, 6398’, Blue Ridge Parkway (35.3676, -82.9902), M.S. Caterino, 8 May 2018 (USNM); Haywood Co.: Richland Balsam, 6069–6397’, Blue Ridge Parkway, A. Smetana, 25 May 1986 (CNC); Haywood Co.: Waterrock Knob, 6275’, Blue Ridge Parkway (35.4643, -83.1374), M.S. Caterino, 29 May 2018 (4, CUAC); Haywood Co.: Waterrock Overlook, 5800’, Blue Ridge Parkway, J.M. & B.A. Campbell, 1 Sep 1967 (4, CNC); Haywood Co.: Browning Knob, 6003–6200’, Blue Ridge Parkway, A. Smetana, 28 May 1986 (CNC); Haywood Co.: Browning Knob, 6140’, Blue Ridge Parkway (35.4630, -83.1310), 22 Sep 2020, M.S. Caterino (7, CUAC); Haywood Co.: Browning Knob, 6200–6220’, Blue Ridge Parkway (35.4633, -83.1315), 22 Sep 2020 M.S. Caterino, A. Haberski (5, CUAC).

This species can be distinguished from its close relative, L. smokiense, only by their aedeagi. In L. smokiense, the entire aedeagus is well sclerotized, whereas the aedeagus of L. balsamense is more typical for the genus with a distinct ventral process (Fig. 9E, F vs Fig. 10D, E). Females can only be identified by geography, association with males, or DNA.

One other microphthalmous species, L. shermani Fall, 1917, occurs above 1000 m elevation in the southern Appalachians, although their ranges do not overlap. Adults are similar in size and appearance but are distinguished by the sexual characters. Males of L. balsamense lack a conspicuous comb of thick black setae on sternite VIII and has no spines on the internal sac of the aedeagus. In females, the gonocoxites lack the pubescence of L. shermani in the lower half.

Habitus (Fig. 9A). Small species, total body length ~ 6 mm long, FL 2.6–2.8 mm long. Coloration: body reddish becoming lighter towards posterior segments of abdomen; legs, palpomeres, and antennae a paler reddish yellow.

Head subquadrate, posterior angles rounded; epicranium coarsely punctate with punctures less dense in median dorsal and anterior regions; interstices with strong transversely reticulate microsculpture throughout; head setose throughout, with long macrosetae projecting at posterior corners of head, corners of eyes, laterally posterior to eyes, and above mandible insertions; gular sutures straight and widely separated, 1/8 width of head but narrowing slightly posteriorly; neck 1/2 as wide as head. Eyes reduced to small white membranes without ommatidia, occupying 1/9 length of head. Antennae moniliform, as long as head and pronotum combined; scape as long as antennomeres II and III combined; antennomeres II–IV obconic and elongate, gradually widening so that antennomeres V–IX are as wide as long; apical antennomere longer, subacute.

Pronotum longer than wide, narrower than head and elytra; widest at anterior angles and tapering slightly posteriorly; anterior angles round, posterior angles less so; punctures small, spaced 1–2× their diameter apart, impunctate at midline; interstices shiny with no microsculpture. Elytra shorter than pronotum, as wide as head, approximately as long as wide; posterior margin slightly sinuate; punctures large and shallow with indistinct edges, irregularly spaced, most approximately one diameter apart; setae angled to posterior; interstices with finely punctate microsculpture. Hindwings vestigial, 0.2 mm long, 1/4 length of elytra. Posterior margin of abdominal tergite VII without palisade fringe.

♂: Posterior margin of sternite VIII with a shallow U-shaped notch (Fig. 10C). Aedeagus 1.1 mm long (Fig. 10E, F), ventral process long, broad, and symmetrical, tapering to a blunt tip; dorsal plate long and situated dorsally; internal sac without spines.

♀: Sternite VIII conical (Fig. 9B); paraprocts undivided anteriorly, apices as long as basal portion; proctiger conical; sternum IX with coxites and valvifers fused, basal half glabrous (Fig. 9B); subgenital plate absent.

This species is named for the Plott Balsam and Great Balsam Mountains.

Lathrobium balsamense inhabits spruce-fir forests above 1500 m in the Great Balsam Mountains and Plott Balsam Mountains (Fig. 13) but is absent from the Great Smoky Mountains where the closely related L. smokiense occurs. It does not occur in spruce-fir forests north of the French Broad River basin, where its microhabitat is inhabited by L. lividum and L. islae. It can be collected from leaf litter but is most common beneath bryophyte mats on boulders. Collected May–Sep.

Holotype ♂ (FMNH): “USA: West Virginia, Pocahontas Co., Monongahela Nat. For. Cranberry Backcountry, past glades, 38.2101, -80.2871, 11-June-2019, C.W. Harden, under large rock nr. steep stream. Spruce/ Northern hardwoods.” / “Caterino DNA voucher, Ext. MSC-7071” / “CLEMSON ENT [QR CODE] CUAC000169036”. Paratypes (4, FMNH, CUAC, VMNH): 3: “USA: WEST VIRGINIA, Pocahontas Co. Monongahela Nat. For. Kennison Mtn Tr., W of Cranberry Glades, 1224m, 38.18002, -80.27846, 10-June-2019, C.W. Harden, Under rock during rain” (also 2 larvae from this collecting event). 1: “USA: WEST VIRGINIA, Pocahontas Co. Monongahela Nat. For. Kennison Mtn Tr., 38.19114N, 80.28524W, 1181m elev. 11.June–3.August.2019, C.W. Harden & L.M. Thompson, Buried jar trap, northern hardwood forest, sandstone boulders present. Rich dark rocky soil. KEN-04” (also 2 larvae from this collecting event).

West Virginia: Pocahontas Co.: Dogway Rd., 4019’, Cranberry Wildlife Management Area (38.1903, -80.2893), C. Harden, 02 Sep 2018 (5, CUAC, VMNH); Pocahontas Co.: Monongahela Nat. For. Cranberry Backcountry (38.1800, -80.2785), C. Harden, 10 Jun 2019, CUAC000187895, CUAC000187896 (3 larvae, CUAC); Pocahontas Co.: Kennison Mountain Trail, Cranberry Wildlife Management Area (38.1900, -80.2780), C. Harden, 11 Sep 2017 (CUAC); Pocahontas Co.: Kennison Mountain Trail, 4388’, Kennison Mountain (38.1979, -80.2915), C. Harden, 19 Sep 2018 (CUAC). Pocahontas Co.: Kennison Mountain Trail, W. of Cranberry Glades, 4015’, Kennison Mountain (38.18002, -80.27846), C. Harden, 06 Oct 2019 (CUAC); Pocahontas Co.: Monongahela Nat. For. Kennison Mtn Tr. (38.19114, -80.28524), C. Harden, 11 Jun–3 Aug 2019, CUAC000187894 (1 larva, CUAC); Pocahontas Co.: Monongahela Nat. For. Kennison Mtn Tr. (38.1903, -80.2893), C. Harden, 2 Sep 2018, CUAC000187897, CUAC000187898 (5 larvae, CUAC).

Three other species of microphthalmous Lathrobium are known from West Virginia and Virginia, L. absconditum, L. lapidum, and L. shermani. The extents of their ranges are unknown and might overlap. Adults of L. hardeni can be distinguished from those of L. absconditum by its smaller body size, transverse combs of thick setae on male sternite VIII, and the presence of a ventral process in the female genitalia, which is unique among the microphthalmous Lathrobium of North America. Males of L. shermani are approximately the same size but have a single row of thick black setae on sternite VIII. Males of L. lapidum are most similar in appearance but are larger and have quadrate elytral margins. The aedeagus of L. lapidum has a characteristic ventral process that reaches the dorsal plate in lateral view, and asymmetrical spines on the internal sac.

Habitus (Fig. 14A). Small species, total body length ~ 6 mm long, FL 3.1–3.3 mm long. Coloration: body pale reddish becoming lighter towards posterior segments of abdomen; legs, palpomeres, and antennae paler reddish yellow.

Similar in appearance to L. absconditum, except head subquadrate; gular sutures straight, separated by 1/15 width of head and narrowing slightly posteriorly. Eyes reduced to small white membranes without ommatidia, occupying 1/8 lateral width of head. Pronotum with sides parallel, just perceptibly narrowed posteriorly; punctation spaced less than one diameter apart, impunctate at midline. Posterior margins of elytra less sinuate; punctures larger.

Figure 14. 

Lathrobium hardeni A habitus B female terminalia C female sternite VIII D male sternite VIII E aedeagus in ventral view F aedeagus in lateral view. Scale bars: 1 mm.

♂: Posterior margin of sternite VIII with broad but shallow emargination and three transverse combs of thick black setae to either side of midline (Fig. 14D). Aedeagus 1.2 mm long; ventral process long, curved ventrally, narrowing to a rounded point with small apical tooth (Fig. 14E, F); dorsal plate long and broad, distal end narrowing to an abrupt point curved away from ventral process with small apical tooth; internal sac with four more-or-less symmetrical spines.

♀: Sternite VIII oblong, apex notched, with micropubescence (Fig. 14C); paraprocts undivided anteriorly, apices shorter than basal portion; proctiger conical; sternum IX with valvifers and coxites fused, finely setose (Fig. 14B); subgenital plate square, distal end with round projection.

First instar larva : Body elongate, 4 mm long; lightly sclerotized (Fig. 15A), head more sclerotized; head light brown, legs and body white, translucent.

Head ovate, tapered posteriad (in dorsal view), dorsoventrally flattened, 1.2× as long as wide, dorsal setae as in Fig. 15A; head 3.2× longer than neck; dorsal ecdysial lines bifurcate halfway between neck and nasale margin; stemmata absent; anterior margin of nasale (Fig. 15B) with nine blunt teeth pointing anteriorly, one short median tooth with edge emarginated, a pair of paramedian teeth, and three pairs of lateral teeth; innermost lateral teeth are small and indistinct; paramedian and lateral teeth armed with nodular setae, and a pair of nodular setae separate median and paramedian teeth; Apotome of gula just reaching tentorial pits.

Antennae (Fig. 15E) length ratios: 1.0:2.4:2.7:1.6; antennomere I triangular; antennomere II with two pores; antennomere three with three elongate macrosetae, three solenidia, one pore; antennomere IV parallel sided with apical solenidia; sensory appendage 0.8× as long as antennomere IV.

Mandibles (Fig. 15C) long, falciform, serrate along basal 1/3 of inner margin, with a single seta near base on outer ventral edge. Maxilla (Fig. 15D) with cardo triangular; stipes elongate, 1.3× longer than cardo; mala digitiform, tapering toward apex, 0.9× as long as palpomere I, with apical sensory appendages and two pores; palpifer with one seta. Maxillary palpomere length ratios: 1.0:1.1:2.5; palpomere II with two setae; palpomere III with one basal sensory appendage and numerous small apical appendages. Labium with prementum subquadrate, basal portion strongly sclerotized; ligula with elongate membranous apex, 3× as long as wide, densely fimbriate, separated from prementum by a lightly sclerotized transverse strip; palpomere I 1.3× as long as II; palpomere II bearing short sensilla at apex.

Dorsal sclerites of thorax with ecdysial lines along midline of body; prothorax as long as wide, as long as tergite II and III combined, narrowed anteriorly, with chaetotaxy as in Fig. 15A; thoracic tergite II wider than III, but with similar chaetotaxy; abdominal sclerites lightly sclerotized, with two small pleural sclerites per segment on each side; basal segment of urogomphus 3× as long as terminal segment, with seven prominent lateral setae; terminal segment of urogomphus slender, with one short and one long apical setae.

Second instar larva : Second instar (Fig. 16A) resembles first, except as follows. Body larger, ~ 7 mm long. Head 1.4× as long as wide, dorsal ecdysial lines bifurcate 1/3 distance between nasale margin and neck; median tooth of nasale projecting, trifurcate (Fig. 16B). Antenna (Fig. 16D) length ratios: 1.0:2.4:2.7:1.6; antennomere IV club shaped. Maxillary palpomere length ratios: 1.0:1.2:2.8 (Fig. 16C). Labial palpomere I 1.6× longer than II and distinctly curved; palpomere II bent near apex. Thoracic tergite II narrower than III; urogomphi slender.

Figure 15. 

Lathrobium hardeni first instar larva A habitus B nasale C mandible D maxilla E antenna. Scale bars: 1 mm (A); 250 μm (B, C); 500 μm (D, E).

Named in honor of the collector Curt Harden. Curt designed the buried pipe trap that has been instrumental in collecting microphthalmous Lathrobium and was the first to collect several of the species described here.

Lathrobium hardeni is known from two locations in the Monongahela National Forest, West Virginia (Fig. 13). Specimens have been collected in buried pipe traps and from underneath embedded rocks, which suggest this species is hypogean. Adults collected May–Sep. Larvae collected Aug–Sep in the same trap as adults.

Figure 16. 

Lathrobium hardeni second instar larva A habitus B nasale C mandible D maxilla E antenna. Scale bars: 1 mm (A); 250 μm (B); 500 μm (C, D, E).

Holotype ♂ (FMNH): “USA: VA: Dickenson Co., 37.2724°N, 82.2956°W, Breaks Interstate Park, Camp Branch Trail, VI.09.2022, C. Harden, under large rock in sandy soil nr rock face, mesic stream hollow.” / “Caterino DNA voucher, Ext. MSC-11164”/ “CLEMSON ENT [QR CODE] CUAC000169038”. Paratypes (1, VMNH): “USA: VA: Scott Co., 36.8584°N, 82.4477°W, Jefferson NF, N of Dungannon, VI.09.2022, C. Harden, On rock face under root/soil mat on base of boulder.” / “Caterino DNA voucher, Ext. MSC-11165” / “CLEMSON ENT [QR CODE] CUAC000169039”.

Figure 17. 

Lathrobium lapidum A habitus B female terminalia C female sternite VIII D male sternite VIII E aedeagus in ventral view F aedeagus in lateral view. Scale bars: 1 mm.

This species’ range might overlap with L. absconditum, L. shermani, and L. hardeni. Compared to these, it has a more rounded head, square elytral margins, and glabrous bases of the gonocoxites. It can be further distinguished from L. absconditum by its smaller size and transverse black setae on male sternite VIII. Males of L. shermani are approximately the same size but have a single setal comb on sternite VIII. Lathrobium hardeni is most similar and distinguishing the two requires comparison of genitalia. Males of L. hardeni have more-or-less symmetrical spines on the internal sac of the aedeagus, and females have a subgenital plate.

Habitus (Fig. 17A). Large species, total body length ~ 8 mm long, FL 3.5 mm long. Coloration: body and appendages pale reddish.

Similar to L. hardeni, except posterior angles of head more strongly rounded. Eyes smaller, reduced to small white membranes occupying 1/9 lateral width of head.

Pronotum with punctures spaced one diameter apart, no line visible down midline. Posterior margin of elytra quadrate; punctures small and shallow, relatively sparse, irregularly spaced 2× their diameters apart.

♂: Posterior margin of sternite VIII with a broad, shallow, V-shaped emargination and three transverse combs of irregularly spaced thick black setae either side of midline (Fig. 17D). Aedeagus 1.3 mm long; ventral process long, reaching dorsal plate in lateral view, apex curved, asymmetrical (Fig. 17E, F); dorsal plate short and oval, distal end with a curved spine; internal sac with four spines, one bulbous and covered with short spikes.

♀: Sternite VIII oblong, apex notched with micropubescence (Fig. 17C); paraprocts undivided anteriorly, apices longer than basal portion; proctiger conical; sternum IX with valvifers and coxites fused, setose in apical 2/3 with a dense patch of thick setae at base (Fig. 17B); subgenital plate absent.

The specific name is from Latin, meaning stone, because both specimens were found on or under rocks.

Lathrobium lapidum is known from two specimens collected in Jefferson National Forest, Virginia (Fig. 18). One was collected under an embedded rock, and the other beneath a root and soil mat on top of a boulder. Collected in June.

Lectotype , Abletobium pallescens Casey herein designated (USNM): “MASS / CASEY bequest 1925 / [red] TYPE USNM 38106 / [handwritten] Abletobium pallescens Jul / Lectotype Abletobium pallescens Casey Desg. Haberski & Caterino.”

Canada, Ontario: Carleton Co.: Fitzroy Provincial Park, 02 May 1979, A. & Z. Smetana, (1 CNC); Grey Co.: Ingli’s Falls, 24 Jun 1985, B. Sinclair (1 CNC). Quebec: Haut Saint François: Johnville, 01 Nov 1987, C. Levesque (1 CNC); same locality, 03 Jul 1988 (1 CNC); same locality, 30 Oct 1988 (1 CNC).

Figure 18. 

Distribution of Lathrobium lapidum (star), L. shermani (triangle), L. solum (square), L. thompsonorum (circle)

This species can be distinguished from all other Abletobium by the presence of eyes with ommatidia.

Body length 6 mm; Body coloration pale red. Eyes small, ~ 30 ommatidia. Head wider than pronotum; gular sutures parallel, widely separate throughout; antennomeres V–VII 1.8× longer than wide. Elytra slightly shorter than pronotum. Females with paraprocts undivided, apices longer than basal portion; sternite VIII conical with small apical notch. Median lobe of aedeagus fully sclerotized and tube-like (Fig. 19).

Canada: ON, QC. USA: MA.

This species had not been previously recorded in Canada because CNC specimens had been misidentified as L. shermani. We corrected these identifications.

Holotype ♂ (MCZ): “[Handwritten] Grandfather Mt Early Sep 1915 N.C. 4000 to 5000 ft. / ♂ / FSherman Collector / H. C. FALL COLLECTION / TYPE [handwritten] shermani / [red] M. C. Z. Type 24086.”

Figures 19, 20. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. 19 L. pallescens 20 L. shermani. Scale bars: 1 mm.

USA: Virginia: Patrick Co.: Stuart (36.7004, -80.2622), 12 Aug–10 Nov 2022, K. Ivanov, J. Means, L. Hightower (5 CUAC and VMNH).

Lathrobium shermani is similar in appearance to L. hardeni, L. lapidum, and L. thompsonorum, all of which have combs of black setae on male sternite VIII. However, those species all have multiple combs, and the combs are continuous across the midline. They also differ in the shape and spines of the aedeagus. Females of L. shermani can be distinguished from L. hardeni by the lack of a subgenital plate, and from L. thompsonorum and L. lapidum by the pubescent gonocoxites.

We present descriptions and illustrations of the male and female genitalia, which were missing from the original description.

Body length 6 mm; body coloration pale red. Head wider than pronotum; eyes reduced to small white membranes without ommatidia; gular sutures parallel and widely separate; antennomeres V–VII 1.8× longer than wide. Elytra shorter than pronotum.

♂: Type specimen differs from specimens collected in Virginia in the number of thick black setae on sternite VIII: type has ~ 8 per comb whereas Virginia specimens have five. Aedeagus large, 1.4 mm long; ventral process long, broad, and bent ventrally in lateral view (Fig. 20D, E); lightly sclerotized median lobe protrudes beyond ventral process in lateral view; dorsal plate short and diamond-shaped; internal sac with four spines, major spine wide and 1/2 as long as ventral process, other three spines shorter than dorsal plate.

♀: Sternite VIII with a shallow, curved notch at apex (Fig. 20B); paraprocts undivided anteriorly, apices approximately equal in length with basal portion; proctiger conical; sternum IX with valvifers and coxites fused, setose with fine pubescence on lower 2/3 (Fig. 20C); subgenital plate absent.

USA: NC, VA.

Lathrobium shermani was previously known from only the holotype. Recently, additional specimens were collected in buried pipe traps in Stuart County, Virginia (Fig. 18). Fall (1917) did not state the method used to collect the holotype, but several attempts by the authors to recollect it at the type locality via litter sifting failed. In their checklist of Canadian beetles, Bousquet et al. (2013) listed L. shermani as occurring in Ontario, but this was due to a misidentification of L. pallecens. Lathrobium shermani is restricted to the southeastern USA.

Holotype ♂ (FMNH): “USA: TN: Sevier Co., 35.6308°N, 83.3904°W, Mt. Kephart, V.6.2018, M. Caterino, Sifted Litter.” / Caterino DNA voucher, Extraction MSC-6218., Extraction Date: XXX/ “CLEMSON ENT [QR CODE] CUAC000169009”. Paratypes (21, FMNH, CUAC, GSNP): 2: same data as holotype (CUAC000169008, CUAC000169010); 8: same locality as type, 35.6311°N, 83.3895°W, VI.5.2018 (CUAC000079121, CUAC000169007, CUAC000169011); 6: same locality as type, 35.6311°N, 83.3895°W, IX.14.2021 (CUAC000156757, CUAC000177157, CUAC000177158, CUAC000177159, CUAC000177160, CUAC000177161); 5: same locality as type, 35.6308°N, 83.3904°W, 6190ft, vi.05.2018 (CUAC000177152, CUAC000177153, CUAC000177154, CUAC000177155, CUAC000177156).

North Carolina: Haywood, Co.: Balsam Mountain Trail, 5167’, Great Smoky Mountains National Park (35.6425, -83.2007), M.S. Caterino, 6 May 2020 (2, CUAC, GSNP); Haywood Co.: Big Cataloochee Mountain, 5725’, Great Smoky Mountains National Park (35.6425, -83.2007), M.S. Caterino, C. Harden, 14 Jul 2020 (3: CUAC, GSNP); Haywood Co.: Big Cataloochee Mountain, 6107’, Great Smoky Mountains National Park (35.6727, -83.1762), M.S. Caterino, 5 Nov 2020 (CUAC); Swain Co.: Clingmans Dome, 6364’, Great Smoky Mountains National Park (35.5613, -83.5006), M.S. Caterino, 5 Jun 2018 (CUAC); Swain Co.: Mills Overlook, Great Smoky Mountains National Park (35.6079, -83.4380), C. Harden, 29 Sep 2020 (CUAC); Haywood Co.: Mount Sterling Trail, 5586’, Great Smoky Mountains National Park (35.6675, -83.1805), M.S. Caterino, 14 Jul 2020 (CUAC). Tennessee: Sevier Co.: Newfound Gap Rd., 4575’, Great Smoky Mountains National Park (35.6237, -83.4163), M.S. Caterino, F. Etzler, 12 Mar 2020 (2, CUAC); Sevier Co.: Mount LeConte, 6467’, Great Smoky Mountains National Park (35.6529, -83.4378), M.S. Caterino, 25 Jun 2019 (CUAC); Sevier Co.: Mount LeConte, 6571’, Great Smoky Mountains National Park (35.6542, -83.4363), M.S. Caterino, 25 Jun 2019 (2, CUAC); Sevier Co.: Indian Gap, 5500’, Great Smoky Mountains National Park, H. & A. Howden, 26 Apr 1956 (CNC).

This species can be distinguished from its close relative, L. balsamense, only by their aedeagi. In L. smokiense, the entire aedeagus is well sclerotized, whereas those of L. balsamense are more typical for the genus with distinct ventral processes (Fig. 9E, F vs Fig. 10D, E). Females can only be identified by geography, association with males, or DNA.

Lathrobium smokiense can be distinguished from L. shermani by the same characters given for L. balsamense.

External morphology is identical to L. balsamense but differs in the aedeagus. Aedeagus (Fig. 9E, F) with median lobe entirely sclerotized, sides meeting at a seam on dorsal side to produce a tube; dorsal plate small and distal; internal sac without spines.

The specific name refers to the Great Smoky Mountains where the species was first collected and is most abundant.

Lathrobium smokiense inhabits spruce-fir forests above 1500 m in the Great Smoky Mountains (Fig. 13). It is not found north of the French Broad River basin (Asheville depression), where its microhabitat is inhabited by L. lividum and L. islae. It can be collected from leaf litter but is most often beneath bryophyte mats on boulders. One specimen was collected from wildcat dung. Collected May–Sep.

Holotype ♂ (FMNH): “USA: Virginia: Botetourt Co., Jefferson NF, 0.25mi NW Blackhorse Gap parking, 37.42796N, 79.7558W, 2425ft., 24.May–19.July-2019, C.W Harden, Buried pipe trap baited with cheese, in gravelly soil, deciduous wooded rocky gully. BHG-02” / “CLEMSON ENT [QR CODE] CUAC000185155”. Paratypes (6, VMNH, CUAC, FMNH): 6: same data as holotype (CUAC000185154, CUAC000177139, CUAC000177140, CUAC000177141, CUAC000177142, CUAC000177143).

Can be distinguished from all other microphthalmous Lathrobium, except L. absconditum, by its large size and unadorned male sternite VIII. It differs from L. absconditum in its transverse middle antennomeres and widely separate gular sutures but is most easily recognized by the aedeagus. Lathrobium solum has a distinct stirrup-shaped major spine in the internal sac, and the ventral process reaches the dorsal plate in lateral view, unlike in L. absconditum (Fig. 21C).

Figure 21. 

Lathrobium solum A habitus B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. Scale bars: 1 mm.

Habitus (Fig. 21A). Large species, total body length ~ 9 mm long, FL 3.5 mm long. Coloration: body and appendages pale reddish, distal segments of antennae lighter.

Similar to L. hardeni, except gular sutures straight and widely separated, 1/8 width of head but narrowing slightly posteriorly. Eyes reduced to small white membranes without ommatidia, occupying 1/10 lateral width of head. Antennomeres II–IV elongate, gradually widening so that antennomeres V–IX are as long as wide. Pronotum without a visible line at midline; interstices shiny with no microsculpture. Posterior margin more sinuate.

♂: Posterior margin of sternite VIII with a broad, shallow emargination (Fig. 21B). Aedeagus 1.5 mm long; ventral process long, reaches dorsal plate, apex produced in an asymmetrical trunk (Fig. 21C, D); dorsal plate short and diamond-shaped; internal sac with five more-or-less symmetrical spines, two largest spines connected by a thin stirrup.

♀: Female unknown.

The specific name is a play on words. In Latin solum can mean soil but also “lonely.” This species is hypogean, and the males are alone until a female is found.

Lathrobium solum is known only from the type locality in Botetourt County, Virginia (Fig. 18), where it was collected from a rocky gully in deciduous forest. All specimens were collected with buried pipe traps, suggesting they are hypogean. Collected May–July.

Holotype ♂ (FMNH): “USA: KY: Monroe Co., 36.6579°N, 85.6259°W, Hestand, Thompson Ln., C.W.Harden, 28.v–3.ix.2022, Buried pipe trap, house-03” / “CLEMSON ENT [QR CODE] CUAC000185201”. Paratypes (12, CUAC, CNCI, and FMNH): 1: same data as holotype (CUAC000177144); 1: same locality as type, 25.ii–8.v.2021 (CUAC000169037, DNA Extract MSC-7054); 5: same locality as type, 22.xii.2022–19.iv.2023; 5: same locality as type, 19.iv–17.vi.2023.

Kentucky: same data as holotype, CUAC000187892 (1 larva, CUAC).

Lathrobium thompsonorum is the only microphthalmous Lathrobium known from west of the Appalachian Plateaus. Males can be distinguished by the unique, twisted ventral process of the aedeagus (Fig. 22E, F). Females have valvifers and coxites fully divided, which is unique among microphthalmous species in the Nearctic.

Habitus (Fig. 22A). Mid-size species, total body length ~ 7.5 mm long, FL 3.0 mm long. Coloration: body and appendages pale reddish.

Similar to L. hardeni, except posterior angles of head more strongly rounded; gular sutures straight, separated by 1/10 width of head but narrowing slightly posteriorly. Eyes reduced to small white membranes without ommatidia, occupying 1/7 lateral width of head. Antennomeres II–IX obconic and longer than wide, V–VII twice as long as wide; apical antennomere longer, subacute. Pronotum with punctures spaced one diameter apart. Posterior margin of elytra more sinuate.

♂: Posterior margin of sternite VIII with rounded emargination, wider than deep; armed with two transverse combs of ~ 20, and one comb of 10 thick black setae (Fig. 22D). Aedeagus 1.4 mm long; ventral process long, asymmetrical, distal end twisted in lateral view (Fig. 22E, F); dorsal plate broad, distal end narrowing to curved point; internal sac with three spines, major spine longer than dorsal plate, 2× length of minor spines.

♀: Sternite VIII oblong (Fig. 22C); paraprocts undivided anteriorly, apices longer than basal portion; proctiger conical; sternum IX with coxites and valvifers fully divided, equal in length (Fig. 22B), coxite narrower and setose, valvifer sinuate and glabrous; subgenital plate absent.

Figure 22. 

Lathrobium thompsonorum A habitus B female terminalia C female sternite VIII D male sternite VIII E aedeagus in ventral view F aedeagus in lateral view. Scale bars: 1 mm.

First instar larva : Body elongate, ~ 5 mm long; lightly sclerotized (Fig. 23A), head more sclerotized; head light brown, legs and body white, translucent.

Figure 23. 

Lathrobium thompsonorum first instar larva A habitus B nasale C mandible D maxilla E antenna. Scale bars: 1 mm (A); 250 μm (B); 500 μm (C, D, E).

Head ovate, strongly tapered posteriad (in dorsal view), dorsoventrally flattened, 1.3× as long as wide, dorsal setae as in Fig. 23A; head 3.6× wider than neck; dorsal ecdysial lines bifurcate 2/5 distance between neck and nasale margin; stemmata absent; anterior margin of nasale (Fig. 23B) as in L. hardeni, but median triangular tooth with edge serrated; Apotome of gula reaching tentoral pits.

Antennal (Fig. 23E) length ratios: 1.0:3.1:3.1:2; antennomere I triangular; antennomere II with two pores; antennomere III with three elongate macrosetae, three solenidia, one pore; antennomere IV club-shaped with apical solenidia; sensory appendage 0.8× as long as antennomere IV.

Mandibles (Fig. 23C) long, falciform, serrate along middle 1/3 of inner margin, with a single seta near base on outer ventral edge. Maxilla (Fig. 23D) with cardo triangular; stipes elongate, 1.6× longer than cardo; mala digitiform, tapering toward apex, 1.1× as long as palpomere I, with apical sensory appendages and two pores; palpifer with one seta. Maxilla as in L. hardeni, but palpomere length ratios: 1.0:1.2:2.5. Labium with prementum quadrate, basal 2/3 strongly sclerotized; ligula with elongate membranous apex, 4× as long as wide, densely fimbriate, separated from prementum by a lightly sclerotized transverse strip; palpomere I 1.4× as long as II; palpomere II bearing short sensilla at apex.

Dorsal sclerites of thorax with ecdysial lines along midline of body; prothorax narrow, 1.2× as long as wide, narrowed anteriorly, chaetotaxy as in Fig. 23A; thoracic tergite II subquadrate; tergite III wider than long; abdominal sclerites lightly sclerotized, with two small pleural sclerites per segment on each side; basal segment of urogomphus 3× as long as terminal segment, with seven prominent lateral setae; terminal segment of urogomphus slender, with one short and one long apical setae.

Named in honor of the Thompson family, who own the property where this species was discovered and graciously allowed it to be collected.

Lathrobium thompsonorum is known only from the type locality in Monroe County, Kentucky (Fig. 18). All specimens were collected with buried pipe traps, suggesting they are hypogean. Adult and larvae were collected in May, found in the same traps.

Subgenus Apteralium Casey, 1905: 70.

Lectotype , Lathrobium brevipenne LeConte, herein designated (MCZ): “[handwritten] L. brevipenne Lec. / Ill. / [red] Type 6447 / Lectotype Lathrobium brevipenne LeConte Desg. Haberski & Caterino.”

USA: Arkansas: Logan Co.: 1 km E Lookout, Mt. Magazine, 23 May 1986, J. M. Campbell, oak-hickory leaf litter (11, CNC); Logan Co.: Brown Springs, Mt. Magazine, 23 May 1986, J. M. Campbell, leaf litter edge of stream (1, CNC); Logan Co.: Lookout, Mt. Magazine, 26 May 1986, J. M. Campbell, deciduous leaf litter (15 CNC); same locality, 14 Nov 2021, A. Haberski, P. Wooden (1 CUAC); Logan Co.: Cameron Bluffs, Mt. Magazine, 27 May 1986, J. M. Campbell, leaf litter at base of cliff (4 CNC); Logan Co.: Cove Lake Campground, 27 May 1986, J. M. Campbell (2 CNC); Stone Co.: Blanchard Springs St. Park, 18 May 1973, J. M. Campbell (1, CNC): same locality, 13 Nov 2021, A. Haberski, P. Wooden, litter on rocky outcrop (1, CUAC); Stone Co.: Sylamore Creek near Gunner Pool Recreation Area, 21 May 2017, C. Harden, litter in dry run (1 CUAC); Franklin Co.: FSR 1510, near Ozark Highland Trail, 21 May 1986, J. M. Campbell (6 CNC); Franklin Co.: Ozark Highlands Trail, 22 May 2017, C. Harden, active at night (1 CUAC); Franklin Co.: Gray Springs, Ozark National Forest, 19 May 1986, J. M. Campbell, leaf litter edge of stream (2 CNC); Pulaski Co.: Pinnacle Mountain State Park, 11 May 1986, J. M. Campbell, flood debris on bank (1 CNC); Washington Co.: Lake Wedington area, 19 May 2017, C. Harden, litter in woods above lake (1 CUAC); Cross Co.: Village Creek State Park, 13 Nov 2021, A. Haberski, P. Wooden (1 CUAC). Illinois: Union Co.: Pine Hills Field Station, 15 May 1967, J. M. Campbell (2 CNC); same locality, 19 May 1967 (1 CNC); St. Clair Co.: 01 Aug 1967, G. W. Bock (1 CNC). Indiana: ‘In.’ (1 USNM). Iowa: ‘Ia.’ (5 USNM). Missouri: Boone Co.: Columbia, 02 May 2011 (1 CNC); Oregon Co.: Surprise Sinkhole Cave, 8.5 mi NE Alton, 26 Dec 1979, J. E. Gardener (1 CNC); St. Louis Co.: Clayton, 21 June 1983, B. F. & J. L. Carr (3 CNC).

Both L. camplyacra and L. carolinae share a similar gestalt with L. brevipenne, but they are endemic to the southern Appalachian Mountains, so their ranges do not overlap. Lathrobium brevipenne can be distinguished from either species by genitalia. Its aedeagus is highly variable but is never fully sclerotized as in L. camplyacra and L. carolinae. Female genitalia of L. brevipenne are also variable, but all have larger and more sclerotized subgenital plates.

Large species, body length 9 mm; body coloration dark red, appendages lighter. Eyes small; elytra shorter than pronotum. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII strongly oblong. Lathrobium brevipenne which has several allopatric populations with distinct genitalic morphotypes and is likely a species complex (Figs 24–26). All morphotypes have a subgenital plate.

USA: AR, IL, IN, IA, MO (Casey 1905).

Holotype ♂ (FMNH): “USA: NC: McDowell Co., 35.2784°N, 82.8008°W, Horse Cove Gap Trail, vii.23.2015, S. Myers, sifted litter.” / “Caterino DNA voucher, Ext. MSC-7059” / “CLEMSON ENT [QR CODE] CUAC000168998”. Paratype (11, CUAC, FMNH): 8: same data as holotype (CUAC000168999, CUAC000177162, CUAC000177163, CUAC000177164, CUAC000177165, CUAC000177166, CUAC000177167, CUAC000177168). 3: same locality as type, 35.2782°N, 82.8018°W.

North Carolina: Jackson Co.: Balsam Mountain Preserve, S. Myers, 15 Jun–7 Jul 2015 (20, CUAC, FMNH, CNC); Transylvania Co.: Courthouse Falls Trail, 3385’ Nantahala National Forest (35.2716, -82.8964), S. Myers, 23 Jul 2015 (CUAC); Jackson Co.: Cowee Bald, 4926’, Nantahala National Forest (35.3270, -83.3361), M.S. Caterino, 9 Jul 2019 (2, CUAC); Jackson Co.: Cowee Bald, 4931’, Nantahala National Forest (35.3270, -83.3359), M.S. Caterino, 15 Sep 2020 (CUAC); Jackson Co.: Dark Ridge, 3467’, Nantahala National Forest (35.3980, -83.1088), S. Myers, 19 Jun 2015 (CUAC); Jackson Co.: Sugarloaf Mountain, 4576’, Nantahala National Forest (35.3699, -83.1212), S. Myers, 15 Jun 2015 (CUAC); Transylvania Co.: Toxaway Mountain, 4746’, Nantahala National Forest (35.1321, -82.9842), M.S. Caterino, 13 Oct 2020 (CUAC); Jackson Co.: 6 km S Cashiers, 3198’ Nantahala National Forest (35.085, -83.1015), A. Smetana, 20 Jun 1986(3, CNC); Jackson Co.: Whiteside Mountains, 4494–4921’, Nantahala National Forest (35.0817, -83.13846), A. Smetana, 21 May 1986 (5, CNC). South Carolina: Oconee Co.: East Fork Chattooga River, Sumter National Forest (34.9843, -83.0981), S. Myers, 4 May 2015 (2, CUAC); Oconee Co.: Indian Camp Creek, Sumter National Forest (34.9899, -83.0724), S. Myers, 4 May 2015 (5, CUAC). Tennessee: Sevier Co.: Newfound, 5000’, Great Smoky Mountains National Park (35.6127, -83.4246), A. Smetana, 09 Jun 1982 (CNC).

Figures 24–26. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. 24 L. brevipenne morphotype 1 25 L. brevipenne morphotype 2 26 L. brevipenne morphotype 3. Scale bars: 1 mm.

This species can be distinguished from the closely related L. carolinae only by the genitalia. Aedeagi are similar, but those of L. camplyacra have bent ventral processes. The terminalia of female L. camplyacra have partially sclerotized subgenital plates and are longer and narrower than those of L. carolinae, with relatively shorter coxites. No intermediate forms are known.

Both L. camplyacra and L. carolinae share a similar gestalt with L. brevipenne. The latter is endemic to the Interior Highlands of the south-central United States. Lathrobium brevipenne can be distinguished from either species by genitalia. Its aedeagus is highly variable in shape but is never fully sclerotized (Figs 24–26). The females of L. brevipenne have larger, more sclerotized subgenital plates.

External morphology (Fig. 5A) identical to L. carolinae. It differs only in the sexual characters.

♂: Aedeagus (Fig. 5E, F) with median lobe well sclerotized; ventral process strongly curved, distal tip lying beyond median foreman in lateral view; dorsal plate long; internal sac with three patches of rugose flagella, visible as one structure when invaginated.

♀: Apical lobes of paraproct shorter than continuous basal portion in dorsal view; proctiger conical; sternum IX with coxites and valvifers fully divided, coxites less than ½ length of valvifers (Fig. 5B); subgenital plate a lightly sclerotized chevron.

The specific name is from the Greek camplyo- meaning bent, and acra meaning tip, in reference to the bent ventral process of the aedeagus.

Lathrobium camplyacra inhabits mid-elevation (600–1600 m) hardwood forests in the Great Balsam, Plott Balsam, and Cowee Mountains of the southern Appalachians (Fig. 27). This area is bordered by the Cullasaja River and Little Tennessee River to the west, the Maggie Valley to the north, and the French Broad River Valley to the east. A single specimen from the CNC collection was reportedly collected from Newfound Gap in the Great Smoky Mountains, which is well outside of this range and needs to be verified.

Figure 27. 

Distribution of L. camplyacra (star), Lathrobium carolinae (circle).

Lectotype , Apteralium carolinae Casey, herein designated (USNM): “♂ / Highlands NC, Jun 6 88 / CASEY bequest 1925 / [red] carolinae – 2, TYPE USNM 38105 / Lectotype Apteralium carolinae Casey Desg. Haberski & Caterino.”

USA: Georgia: Rabun Co.: Satoloh, 13 Jun 1957, R. M. Mason (3, CNC); Rabun Co.: Rabun Bald, 11 May 2021, M. Caterino (1, CUAC); Dillard Co.: 15 Apr 1948, F. Rapp (1, CNC); Union Co.: Brasstown Bald, 02 Jul 2020, M. Caterino (1, CUAC); same locality, 17 Sep 2020 (1, CUAC); Union Co.: Little Bald Mountain, 02 July 2020, M. Caterino (2, CUAC). North Carolina: same data as holotype (1, USNM); Macon Co.: Hwy 64 near Dry Falls NW Highlands, 16 May 1986, A. Smetana (1, CNC): Macon Co.: near Cliffside Lake Campground NW highlands 16 May 1986, A. Smetana (3, CNC); Macon Co.: Van Hook Glade, 4 mi W Highlands, 30 Aug 1967, J. M. & B. A. Campbell (1, CNC); Macon Co.: Copper Ridge Bald, 09 Jul 2019, M. Caterino (2, CUAC); Macon Co.: Forest Service Rd 77, 10 Jul 2020, A. Deczynski (1, CUAC); Macon Co.: Hickory Branch Trail, 26 Jul 2015, M. Caterino, S. Langton-Myers, hardwood litter (5, CUAC); Macon Co.: Hickory Gap, 16 Jul 2015, M. Caterino, S. Langton-Myers (1, CUAC); Macon Co.: Jones Gap, 16 July 2015, M. Caterino, S. Langton-Myers, litter around bracket fungus (8, CUAC); same data, except 22 July 2015, hardwood litter against logs (4, CUAC); Macon Co.: Wayah Bald Rd, 18 Apr 2020, C. Harden, under rock by seep (1, CUAC); Clay Co.: Chunky Gal Trail, 01 Sep 2020, M. Caterino, S. Langton-Myers (1, CUAC); Clay Co.: Riley Knob, 11 May 2020, M. Caterino (1, CUAC); Clay Co.: Shooting Creek Bald, 11 May 2020, M. Caterino (1, CUAC); Caly Co.: Tusquitee Bald, 06 Jul 2021, M. Caterino (1, CUAC); Cherokee Co.: London Bald Trail, 26 Jul 2015, M. Caterino, S. Langton-Myers, hardwood litter (4, CUAC); Graham Co.: Cherohala Skyway, 27 Sep 2020, C. Harden (1, CUAC); Graham Co.: Huckleberry Knob, 04 May 2020, M. Caterino (1, CUAC); same data, except 13 Oct 2020 (2, CUAC); Joyce Kilmer Memorial Forest, 24 Jun 2015, M. Caterino, S. Langton-Myers (8, CUAC); same data, except 20 Jul 2015 (7, CUAC); Graham Co.: Teyahalee Bald, 09 Jul 2019, M. Caterino (1, CUAC); Haywood Co.: Balsam Mountain Trail, 05 Sep 2020, M. Caterino (1, CUAC); Haywood Co.: Pisgah National Forest, 14 July 2020, A. Deczynski (1, CUAC); Swain Co.: Miller Cove Trail, 20 July 2015, M. Caterino, S. Langton-Myers (1, CUAC); Swain Co.: Smokemont Campground, 10 km N Cherokee, 09 Jun 1982, A. Davies (9, CNC); Swain Co.: Lakeshore Trail, Great Smoky Mountains National Park, 18 July 2003, A. Tishechkin (2, LSAM); Transylvania Co.: Twentymile Trail near Twentymile Creek, 19 Oct 2007, I. M. Sokolov, litter on rock explosion (1, LSAM). Tennessee: Blount Co.: Cades Cove, Great Smoky Mountains National Park, Jun 1954, H. Howden (1, CNC); Blount Co.: Greenbrier Cove, Great Smoky Mountains National Park, 27 Jun 2001, C. Carlton, A. Tishechkin, V. Moseley (1, LSAM); Monroe Co.: Indian Boundary Camp, 28 May 2020, C. Harden (1, CUAC).

This species can be distinguished from L. camplyacra only by the genitalia. Aedeagi are similar but the ventral processes of L. carolinae are straight, not bent as those of L. camplyacra. The terminalia of female L. carolinae lack subgenital plates and are shorter and wider than those of L. camplyacra. No intermediate forms are known.

Figure 28. 

Lathrobium carolinae second instar larva A habitus B head in lateral view C nasale D mandible E maxilla F antenna. Scale bars: 1 mm (A, B); 100 μm (C); 250 μm (D, E, F).

Lathrobium carolinae can be distinguished from L. brevipenne by the same characters given for L. camplyacra.

The original description lacked a description of the genitalia. We present descriptions and illustrations of the male and female genitalia, as well as the first description of the mature larva.

♂: Aedeagus 1.7 mm long (Fig. 4D, E), median lobe well sclerotized; ventral process relatively straight, distal tip not bending beyond median foreman in lateral view; dorsal plate long; internal sac with three patches of rugose flagella, visible as two structures when invaginated.

♀: Paraprocts undivided anteriorly, apices shorter than basal portion; proctiger conical; sternum IX with coxites and valvifers fully divided, coxites ¾ length of valvifers (Fig. 4A); subgenital plate absent.

Second instar larva : Larvae were associated with adults by DNA barcoding. Body elongate, ~ 5 mm long; well sclerotized (Fig. 28A); head, thoracic, and abdominal tergites brown, appendages light yellow, intersegmental membrane white, translucent.

Head ovate, widest at stemmata and slightly tapered posteriad (in dorsal view), dorsoventrally flattened, 1.3× as long as wide; dorsal setae as in Fig. 28A; head 2.9× as wide as neck; dorsal ecdysial lines bifurcate 3/8 distance between neck and nasale margin; six stemmata present, arranged as in Fig. 28B; anterior margin of nasale (Fig. 28C) with nine blunt teeth pointing anteriorly, one round median tooth with edge serrated, a pair of paramedian teeth, and three pairs of lateral teeth; innermost lateral teeth are small and indistinct; paramedian and lateral teeth armed with nodular setae, and a pair of nodular setae separate median and paramedian teeth; Apotome of gula reaching tentoral pits.

Antennae (Fig. 28F) length ratios: 1.0:2.7:2.8:1.5; antennomere I triangular; antennomere II with two pores; antennomere III with three elongate macrosetae, three solenidia, one pore, and a curved sensory appendage 2/3 as long as terminal antennomere; antennomere IV club-shaped with apical solenidia; sensory appendage 0.6× as long as antennomere IV.

Mandibles (Fig. 28D) long, falciform, serrate along middle 1/3 of inner margin, with a single seta near base on outer ventral edge. Maxilla (Fig. 28D) with cardo triangular; stipes elongate, 1.3× longer than cardo; mala digitiform, tapering toward apex, 0.7× as long as palpomere I, with apical sensory appendages and two pores; palpifer with one seta. Maxillary palpomere length ratios: 1.0:1.2:2.2; palpomere II with two setae; palpomere III with one basal sensory appendage and numerous small apical appendages. Labium with prementum trapezoidal, basal ¾ strongly sclerotized; ligula with elongate membranous apex, 3× as long as wide, densely fimbriate, separated from prementum by a distinctly sclerotized transverse strip; palpomere I 1.8× as long as II; palpomere II bent near apex and bearing short sensilla at apex.

Dorsal sclerites of thorax with ecdysial lines along midline of body (Fig. 28A); prothorax narrow, 1.3× as long as wide, widest posteriorly and narrowing anteriorly, chaetotaxy as in Fig. 28A; thoracic tergites II and III subequal in width and length; abdominal sclerites well sclerotized, with two small pleural sclerites per segment on each side; urogomphi broken off of only known specimen.

Lathrobium carolinae inhabits mid-elevation (600–1600 m) hardwood forests in the Appalachian Mountains, from Georgia to the French Broad River basin in North Carolina (Fig. 28), except in those ranges occupied by L. camplyacra as described above. Collected Feb–Oct.

Subgenus Lathrobioma Casey, 1905: 72.

Lectotype , Lathrobium divisum LeConte, herein designated (MCZ): “Vanc. / [handwritten] L. divisum Lec. / COLLECTION / TYPE [handwritten] divisum / [red] Type 6453 / Lectotype Lathrobium divisum LeConte Desg. Haberski & Caterino.” Lectotype, Lathrobium franciscanum Casey, herein designated (USNM): “LosGatos CAL/ CASEY bequest 1925 / [handwritten] Los Gatos is in Santa Clara Co. not far from Sta. Cruz California / [red] TYPE USNM 38114 / Lectotype Lathrobium franciscanum Casey Desg. Haberski & Caterino.”

USA: California: Santa Clara Co.: Los Gatos (1, USNM); Mendocino Co.: Gualala (1, USNM); Illinois (1, MCZ).

This species can be distinguished from other Lathrobioma by its large size. Additionally, males are the only Lathrobioma to lack an emargination on sternite VIII and have an asymmetrical aedeagus. Females have paraprocts subequal in length to the basal portion of tergite IX, while other species have paraprocts that are short or fully divided.

Large species, body length 7–8 mm. Body coloration red, elytra bicolored, appendages lighter yellow. Gular sutures arcuate; antennomeres V–VII as long as wide. Elytra as long as pronotum. Females with paraprocts undivided, apices as long as basal portion; sternite VIII weakly oblong. Male sternite VIII without emargination, thick black setae at apex; genitalia as in Fig. 29.

Canada: BC. USA: CA, IL, OR, WA (Newton 2022).

Lathrobium franciscanum is reduced to synonymy with Lathrobium divisum because the distinguishing characters given by Casey (1905) were insufficiently distinctive. Lathrobium franciscanum was described from one female and one male, which were differentiated from L. divisum based on subtle morphological differences in somatic characters. Its body was supposedly “more slender,” punctures “somewhat sparser,” head “not so large,” and prothorax “slightly narrower” than the head as opposed to “much narrower” in L. divisum (Casey 1905). These differences are difficult to see and fall within the range of intraspecific variation in longer series of other Lathrobium. We examined the genitalia of both species and found no differences in the shape of their aedeagi.

Casey (1905) placed L. divisum in Lathrobium s. str., but after examining the types, we transfer it to Lathrobioma based on the following synapomorphies: metatarsi compact, tarsomeres I–IV subequal in length, each ~ 1/3 as long as fifth tarsomere; maxillary palpomere III more than 0.4× as wide as long; and male sternite VIII with bristles positioned apically. The final character is presented here for the first time.

Lectotype , Lathrobioma nanula Casey, herein designated (USNM): “MASS / CASEY bequest 1925 / [red] TYPE USNM 38139 / [handwritten] nanula / Lectotype Lathrobioma nanula Casey Desg. Haberski & Caterino.”

Figures 29–34. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D Aedeagus in lateral view. 29 L. divisum 30 L. nanulum 31 L. othioides 32 L. scolopaceum 33 L. tenue 34 L. amplipenne. Scale bars: 1 mm.

Same data as lectotype (1, USNM).

Lathrobium nanulum can be distinguished from other Lathrobioma by unique genitalic characters. The ventral process of the aedeagus is narrow instead of broad. Female sternum IX with valvifers and coxites fully divided instead of fused.

Small species, body length 5 mm; body and appendages dark red coloration. Gular sutures arcuate; antennomeres V–VII wider than long; maxillary palpomere III more than 0.4× as wide as long. Elytra 1.2× longer than pronotum. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII oblong. Dorsal plate and ventral process of aedeagus with large apical teeth (Fig. 30).

USA: MA.

Blackwelder (1939), in his revision of the paederine genera, placed L. nanulum in the subgenus Deratopeus, now a synonym of the genus Tetartopeus, without providing any explanation. We transfer it back to Lathrobioma, because it lacks any of the defining characters of Tetartopeus, such as a narrow neck, but does share the subgeneric synapomorphies of Lathrobioma listed above for L. divisum.

Lectotype , Lathrobium othioides LeConte, herein designated (MCZ): “Mas. / ♂ / [handwritten] L. othioides Lec. / [red] Type 6448 / Lectotype Lathrobium othioides LeConte Desg. Haberski & Caterino.”

Canada: Lake Superior (2, USNM). USA: Iowa: ‘Ia.’ (1, USNM). Massachusetts: ‘Mass.’ (5, MCZ); Norfolk Co.: Brookline, 21 Mar 1899 (1, MCZ); same locality, 17 Apr 1899, C. A. Frost (1, CUAC); same data, except 09 Apr 1899 (1, MCZ); ‘Mass’ (1, USNM). New Jersey: ‘N.J.?’ (2, USNM).

Males have distinctive aedeagi with the apex of the ventral process divided into two projecting horns, absent in all other Lathrobioma. Females can be difficult to distinguish from L. tenue, but their gonocoxites are generally more robust and convex in the basal half.

Body length 6 mm; body coloration dark red, appendages lighter red. Gular sutures arcuate; maxillary palpomere III > 0.4× as wide as long; antennomeres V–VII as wide as long. Elytra as long as pronotum. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII weakly oblong. Aedeagus with characteristic projections of ventral process (Fig. 31).

Canada: ON, NB, QC (Bousquet et al. 2013). USA: IA, NJ, MA, RI.

Bernhauer and Schubert (1912) listed L. inops as a synonym of L. othioides, but after comparing the types, we determined this was incorrect. The aedeagus of L. othioides is quite distinctive and that of the L. inops lectotype did not match it. Instead, it was indistinguishable from that of L. scolopaceum, with which we synonymize L. inops below.

Lectotype , Lathrobioma scolopacea Casey, herein designated (USNM): “B MASS / CASEY bequest 1925 / [red] TYPE USNM 38143 / [handwritten] scolopacea / Lectotype Lathrobioma scolopacea Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma dakotana Casey, herein designated (USNM): “[handwritten] Bismarck Dak / CASEY bequest 1925 / [red] TYPE USNM 38136 / [handwritten] Lathrobioma dakotana / Lectotype Lathrobioma dakotana Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma virginica Casey, herein designated (USNM): “Grafton WV / CASEY bequest 1925 / [red] TYPE USNM 38139 / Lectotype Lathrobioma virginica Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma inops Casey, herein designated (USNM): “L.Sup / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38144 / Lectotype Lathrobioma inops Casey Desg. Haberski & Caterino.”

Canada: Ontario: ‘L. Sup’ (1, USNM). USA: Massachusetts: ‘Mass’ (2, USNM); Middlesex Co.: Framingham, 1944, C. A. Frost (1, MCZ). Maine: Knox Co.: Isle-au-haut, Aug 1905 (1, MCZ). New Hampshire: Grafton Co.: Downes Brook, Potash Mountain, 05 Jun 2021, A. Haberski (2, CUAC); Grafton Co.: Mount Lafayette, 04 Jun 2012, A. Haberski (1, CUAC); Strafford Co.: Spruce Hole Conservation Area, D. S. Chandler (1, UNHC); Grafton Co.: Hubbard Brook Experimental Forest, D. S. Chandler (1, UNH).

Females of L. scolopaceum are readily distinguished from all other Lathrobioma by their divided paraprocts. Males can be distinguished by their uniquely shaped aedeagus, which has a ventrally projected apex of the ventral process.

Body length 6 mm; coloration reddish, appendages lighter. Gular sutures arcuate; maxillary palpomere III > 0.4× as wide as long; antennomeres V–VII as long as wide. Elytra at least as long as pronotum, sometimes longer and wider. Females with paraprocts divided; sternite VIII weakly oblong. Characteristic aedeagus as in Fig. 32.

Canada: ON, NB, NS, QC (Bousquet et al. 2013). USA: IA, MA, ME, NH, ND, RI, VA, WV (Newton 2022).

We reduce Lathrobium dakotanum, Lathrobium virginicum, and Lathrobium inops to synonymy with Lathrobium scolopaceum because the distinguishing characters given by Casey (1905) were inaccurate. Lathrobium dakotanum and L. virginicum were each described from a single female and differentiated from L. scolopaceum based on their elytra being at least equal in length to the pronotum, as opposed to “much shorter” (Casey 1905). We measured the specimens in Casey’s collection and found that the elytra of L. scolopaceum were 1.1× longer the pronotum, approximately the same as that of L. dakotanum and L. virginicum.

Lathrobium virginicum was further differentiated by having a head as wide as its elytra, as opposed to narrower in L. scolopaceum, L. dakotanum, and L. inops. Upon measuring, we found all four species have a head wider than their pronotum.

Lathrobium inops was distinguished as being larger and more slender than L. scolopaceum (Casey, 1905), but this was not the case.

The genitalia are identical in all four species.

Lectotype , Lathrobioma tenuis Casey, herein designated (MCZ): Pink Disc / “[handwritten] L. tenue Lec. / [red] Type 6452 / Lectotype Lathrobium tenue LeConte Desg. Haberski & Caterino.” Lectotype, Lathrobioma hespera Casey, herein designated (USNM): “Br.C/ CASEY bequest 1925 / [red] TYPE USNM 38140 / Lectotype Lathrobioma hespera Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma nigrolinea Casey, herein designated (USNM): “Winnipeg Man./ CASEY bequest 1925 / [handwritten] nigrolinea / [red] TYPE USNM 38141 / Lectotype Lathrobioma nigrolinea Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma oregona Casey, herein designated (USNM): “Port Oreg/ CASEY bequest 1925 / [handwritten] oregona / [red] TYPE USNM 38142 / Lectotype Lathrobioma oregona Casey Desg. Haberski & Caterino.” Lectotype, Lathrobioma shoshonica Casey, herein designated (USNM): “Or. / ♂ / CASEY bequest 1925 / [handwritten] shoshonica / [red] TYPE USNM 38138 / Lectotype Lathrobioma shoshonica Casey Desg. Haberski & Caterino.”

Canada: Ontario (3, MCZ). USA: Colorado: Alamosa (1, MCZ). Connecticut: New Haven (1, USNM). Michigan: ‘Mic.’ (1, MCZ). Oregon: ‘Oreg’ (1, USNM). Rhode Island: ‘R.I.’ (7, USNM). Virginia: Highland Co.: Water Sinks, Lucas Tract, 04 May 2019, C. Harden, gravel stream bank (1, CUAC). West Virginia: Pocahontas Co.: Cranberry Wilderness, Monongahela National Forest, 11 Jun 2019, C. Harden, under rock near stream in spruce/hardwoods (1, CUAC).

Males of L. tenue have a broadly rounded and symmetrical ventral process of the aedeagus that is unique among Lathrobioma spp. Females are difficult to differentiate from L. othioides, but their gonocoxites are narrower and concave in the basal half.

Body length 6 mm; coloration dark, appendages yellow or light red. Gular sutures arcuate; maxillary palpomere III > 0.4× as wide as long; antennomeres V–VII as long as wide. Elytra at least as long as pronotum, sometimes longer and wider. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII weakly oblong. Ventral process of aedeagus broadly rounded (Fig. 33).

Canada: BC, MB, ON, QC, SK (Bousquet et a. 2013). USA: CO, CT, ID, MA, MI, NY, OR, RI, VA, WA, WV (Newton 2022).

We reduce Lathrobium hesperum, Lathrobium oregonum, Lathrobium nigrolinea, and Lathrobium shoshonicum to synonymy with Lathrobium tenue due to insufficient morphological differences between species. Lathrobium shoshonicum and L. hesperum were described as having elytra longer than their pronota, in contrast to L. tenue which supposedly had elytra shorter than their pronota. However, upon measuring the type specimen and those in Casey’s collection, we found L. tenue also has elytra longer than its pronotum.

Lathrobium oregonum and L. nigrolinea were differentiated primarily on the shape of the emargination of male sternite VIII. In these species, the setae at the tips of the emargination are inflexed, rather than diverging as in L. tenue. This difference was based on a single male of each species and could represent normal variation, regional difference, or coincidence.

We examined the genitalia of all five species and found no differences.

Subgenus Lathrobium s. str.

Litolathra Casey, 1905: 71.

Lathrobium (Litolathra): Bernhauer and Schubert 1912: 40.

Lectotype , Lathrobium amplipenne Casey, herein designated (USNM): “N. Y. / CASEY bequest 1925 / [red] TYPE USNM 38107 / [handwritten] Lathrobium amplipenne / Lectotype Lathrobium amplipenne Casey Desg. Haberski & Caterino.”

Illinois: Union Co., 1 mi E Wolf Lake, 8.V.1976, A. Smetana (2, CNC); 2 mi NE Reynoldsville, 9.V.1976, A. Smetana (1, CNC). Indiana: Tippecanoe Co., 27.X.1956, N.M. Downie (1, CNC). Louisiana: Concordia Pa. [Park?], 5 mi W Ferriday, 1.V.1976, A. Smetana (1, CNC). Missouri: St. Louis Co., 9.V.1920, G.W. Bock (1, CNC). New York: Tompkins Co.: Ithaca Valley, (9, USNM). Pennsylvania: ‘Penn.’. F. C. Bowditch (1, MCZ). South Carolina: Charleston Co.: Ravenel, 05 May 2001, J. C. Ciegler, UV light (2, CUAC); Dorchester Co.: Bluff Trail, McAlheny Nature Preserve, Reevesville, 11 May 2013, J. C. Ciegler (1, CUAC); Marion Co.: Woodbury, 10 Sep 2011, J. C. Ciegler (1, CUAC).

The habitus of this species closely resembles that of L. armatum, L. geminum, L. praelongum, and L. pedale. Males differ from those species in their unique sternite VIII, which has three small emarginations at the apex and two longitudinal patches of dense setae (Fig. 34B). Females are difficult to tell apart from L. armatum and L. praelongum. Their paraprocts are slightly shorter than those of L. armatum, and longer than those of L. amplipenne, relative to the basal portion of tergite IX. Females can be easily distinguished from L. geminum, which has gonocoxites shorter than paraprocts, and L. pedale, which has valvifers and coxites divided.

Large species, body length 10 mm; body coloration dark, appendages lighter red, elytra bicolored. Gular sutures converging, nearly touching posteriorly; antennomeres V–VII longer than wide. Elytra 1.3× as long as pronotum. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII conical with shallow notch at tip. Male sternite VIII with three emarginations (Fig. 34B). Genitalia as in Fig. 34. The length of the ventral process of the aedeagus can vary.

Canada: ON, NB, QC (Bousquet et al. 2013). USA; IL, IN, LA, MI, MO, NY, PA, SC.

Holotype not examined. It was presumably lost with much of Say’s collection (Mawdsley, 1993). Lectotype Lathrobium deceptivum Casey, herein designated (USNM): “N.Y. / CASEY bequest 1925 / [red] TYPE USNM 38108 / [handwritten] deceptivum / Lectotype Lathrobium deceptivum Casey Desg. Haberski & Caterino.” Lectotype Lathrobium subaequale Casey, herein designated (USNM): “N.J. / CASEY bequest 1925 / [red] TYPE USNM 38110 / [handwritten] subaequale / Lectotype Lathrobium subaequale Casey Desg. Haberski & Caterino.” Lectotype Lathrobium procerum Casey, herein designated (USNM): “Ill. / CASEY bequest 1925 / [red] TYPE USNM 38110 / [handwritten] procerum / Lectotype Lathrobioma procerum Casey Desg. Haberski & Caterino.” Lectotype Lathrobium nigrolucens Casey, herein designated (USNM): “Mass/ CASEY bequest 1925 / [red] TYPE USNM 38109 / [handwritten] nigrolucens / Lectotype Lathrobioma nigrolucens Casey Desg. Haberski & Caterino.”

Canada: Ontario (1, USNM). Quebec: MRC des Deux-Montagnes, Parc National d’Oka, 06 May 2023, R. Vigneault, handpicked near a beach (1, NBC). USA: Illinois (6, USNM). Indiana: Allen Co.: New Haven, 15 Jun 1986, N. M. Downie (1, UNHC). Massachusetts: ‘Mass.’ (1, MCZ). Michigan: ‘Mi.’ (2, MCZ). Missouri: ‘Mo.’ (1, MCZ). New Hampshire: Strafford Co.: Spruce Hole Conservation Area, 3 mi SW Durham, 09 Jun 1982, D. S. Chandler, bog margin in oak, beech, huckleberry litter (17, UNCH); same data, except 16 Apr 1982, marsh (1, UNHC); same data, except 22 Apr 1982, near bog edge (2, UNHC); same data, except 30 Aug 1982, along pond (5, UNHC); Hillsborough Co.: Antrim, 11 Jun 1932, C. A. Frost (1, UNHC); Rockingham Co.: Hampton, 15 Mar 2003, S. A. Shaw (1, UNHC); Rockingham Co.: Hampton, 10 Jun 2011 (1, UNHC); Grafton Co.: Rumney, 22 Apr 1926, P. J. Darlington (1, MCZ). New York (7, USNM); North Carolina (1, MCZ). Vermont: Burlington Co., Apr 1953, D. S. Chandler (1, UNHC).

Lathrobium armatum is similar in external appearance to L. amplipenne and L. pedale and are especially difficult to distinguish form L. praelongum. The female terminalia of L. armatum are shorter with a more convex inner margin, and its paraprocts are longer relative to the basal portion of tergite IX than in the aforementioned species. Males are easily identified by their aedeagus, which has a unique rear-facing hook projecting form the apex of the dorsal plate.

Large species, body length 10 mm; body coloration dark, appendages red, elytra sometimes bicolored. Gular sutures converging, nearly touching posteriorly; antennomeres V–VII as wide as long. Elytra 1.3× longer than pronotum. Females with paraprocts undivided, apical lobes shorter than basal portion, ~ 0.9× as long; sternite VIII conical. Male sternite VIII either with a small round emargination or no emargination. Dorsal plate of aedeagus with large, rear-facing hook (Fig. 35).

Canada: ON, NB, QC (Bousquet et al. 2013). USA: DC, IL, IN, MA, MI, MO, NH, NJ, NY, NC, SC, VT.

We reduce Lathrobium deceptivum, Lathrobium nigrolucens, and Lathrobium subaequale to synonymy with Lathrobium armatum based on a lack of distinguishing morphological characters. Casey recognized that the herein synonymized species were difficult to discriminate and that they might not be full species. He differentiated them based on a combination of elytra length and color. Lathrobium subequale was described as having bicolored elytra, in contrast to the solid black elytra of L. armatum. However, this character is variable and specimens of L. armatum in LeConte’s collection have lightly bicolored elytra. Lathrobium deceptivum and L. nigrolucens were distinguished from L. armatum based on the length of elytra relative to pronotum, but many species are dimorphic for this character. Lathrobium deceptivum was described from two males, L. subaequale from a single female, and L. nigrolucens from a short series of both. Genitalia of all of the above species were indistinguishable.

Lectotype , Lathrobium confusum LeConte, herein designated (MCZ): White disc / “[handwritten] L. confusum Lec. / [handwritten] 8117 / [red] Type 6456 / Lectotype Lathrobium confusum LeConte Desg. Haberski & Caterino.” Lectotype, Litolathra amputans Casey, herein designated (USNM): “Ia. / CASEY bequest 1925 / [red] TYPE USNM 38132 / [handwritten] amputans / Lectotype Litolathra amputans Casey Desg. Haberski & Caterino.” Lectotype, Litolathra convictor Casey, herein designated (USNM): “City ham / CASEY bequest 1925 / [red] TYPE USNM 38130 / [handwritten] convictor / Lectotype Litolathra convictor Casey Desg. Haberski & Caterino.” Lectotype, Litolathra inornata Casey, herein designated (USNM): “Wshngtn D.C. / CASEY bequest 1925 / [red] TYPE USNM 38133 / [handwritten] inornata / Lectotype Litolathra inornata Casey Desg. Haberski & Caterino.” Lectotype, Litolathra suspecta Casey, herein designated (USNM): “N.Y. / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38131 / [handwritten] suspecta / Lectotype Litolathra suspecta Casey Desg. Haberski & Caterino.”

USA: Connecticut: New Haven Co.: New Haven (5, USNM). Massachusetts: ‘Mass’ (4, USNM). New Hampshire: Strafford Co.: Cooper Cedar Woods 1mi SE New Durham, 15 Aug 1982, D. S. Chandler, cedar swamp litter (1, UNHC); Strafford Co.: Foss Farm Rd water tower, 22 Oct 1982, W. J. Morse (1, UNHC); same data, except 30 Aug 1982 (3, UNHC); Strafford Co.: Spruce Hole Conservation Area 3 mi SW Durham, 09 Jun 1982, D. S. Chandler, litter on bog edge (12, UNHC); Strafford Co.: 1 mi SW Durham, 30 Oct 1982, W. J. Morse (4, UNHC). New Jersey: Mercer Co.: Princeton, 07 Jun 2021, A. Deczynski (1, CUAC). New York: ‘N. Y.’ (4, USNM); ‘skill NY’ [=Catskills] (1, USNM); Yates Co.: Dundee (1, USNM). North Carolina: Henderson Co.: Bearwallow Mountain, 10 Aug 2021, M. Caterino, A. Haberski, flood debris (1, CUAC); Jackson Co.: 6 km S Cashiers, 20 Jun 1986, A. Smetana (1, CNC). South Carolina: Pickens Co.: Clemson, 07 May 1940 (1, CUAC). Virginia: Shenandoah Co.: George Washing National Forest, Crooked Run Rd, Rte 720, 17 Mar 2019, C. harden, litter/duff along stream in laurel hardwoods (1, CUAC); Shenandoah Co.: George Washing National Forest, Dead Deer Creek near Signal Knob, 01 May–31 May 2015, C. Harden, flood debris (1, CUAC); Shenandoah Co.: George Washing National Forest, Rte 678 2 mi S jct w/619, 03 Jul 2018, C. Harden (1, CUAC); Shenandoah Co.: Passage Creek near Elizabeth Furnace Recreational Area, 20 Mar 2017, C. Harden, flood debris (1, CUAC); Highland Co.: Locust Springs, George Washing National Forest, 28 Jul 2017, C. Harden (3, CUAC); Smyth Co.: Mount Rogers, 15 Jun 2019, C. Harden (1, CUAC); Smyth Co.: Whitetop Mountain, 16 Jun 2019, C. Harden, litter along stream (1, CUAC); Powhatan Co.: Powhatan State Park, 02 Apr 2017, C. Harden, wetlands, nr vernal pool (1, CUAC); Washington D. C.: ‘D. C.’ (1, USNM). West Virginia: Pocahontas Co.: Cranberry Wilderness, Monongahela National Forest, 11 Jun 2019, C. Harden, under rock nr steep stream in spruce/hardwoods (1, CUAC); Pocahontas Co.: Gaudineer Knob Scenic Area, 29 Jun 2017, C. Harden (2, CUAC); Pocahontas Co.: Kennison Mountain FS Rd 232, 20 May 2018, C. Harden, litter nr rushing ephemeral rivulet (1, CUAC); Pocahontas Co.: Pocahontas Trail near Cranberry Mountain Lodge, 10 Sep 2017, C. Harden (1, CUAC).

Lathrobium confusum superficially resembles Lathrobioma, although it is not closely related. It differs from all Lathrobioma by having long antennomeres, and males lack the thick black setae on sternite VIII that are characteristic of the subgenus. Lathrobium confusum is more closely related to L. rhodeanum, with which is shares characteristically long antennomeres and paraprocts. The two can be distinguished by the hind tarsomeres which are shorter and more compact in L. confusum.

Body length 6 mm; coloration dark, appendages light yellow. Gular sutures arcuate (Fig. 1C); antennomeres V–VII longer than wide. Elytra approximately as long as pronotum. Male sternite VIII with shallow notch and no thick setae; Female with paraprocts undivided, apices 2.6× longer than basal portion, sternite VIII conical; genitalia as in Fig. 36.

Canada: ON, NB, QC (Bousquet et al. 2013). USA: CT, DC, IA, MA, NH, NJ, NY, NC, SC, VA, WV.

We reduce Lathrobium amputans, Lathrobium convictor, Lathrobium inornatum, and Lathrobium suspectum to synonymy with Lathrobium confusum, because the characters given by Casey (1905) were either inaccurate or insufficiently distinctive. Lathrobium amputans was described as having elytra shorter than wide in females, and those of L. confusum were said to be subequal. Upon measuring the types, we found the elytra to be subequal in length and width in both species. Lathrobium convictor was described as having elytra equal in length to the pronotum, and those of L. confusum were described as shorter than the pronotum, but we found the elytra of both species were 1.1–1.2× longer than the pronotum.

Lathrobium inornatum was described as having the emargination of sternite VIII smaller, shallower, and more broadly rounded compared to that of L. confusum, but we found no differences in width or depth. The difference in shape was modest and the emargination of L. amputans was actually less round than that of L. confusum.

Lathrobium suspectum and L. confusum were differentiated based on obscure minutia such as form “moderately stout” vs “rather stouter”, pronotal punctures “fine and moderately sparse” vs “moderately coarse and sparse,” but these differences were not observed in the types (Casey 1905). The length of the antennae relative to the head and pronotum combined were supposedly shorter in L. suspectum, but this too proved incorrect when measured.

We examined the genitalia of the above species and found no differences in aedeagi or female terminalia.

Lectotype Litolathra cruralis Casey, herein designated (USNM): “N. J. / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38129 / Lectotype Litolathra cruralis Casey Desg. Haberski & Caterino.”

USA: Iowa: ‘Ia.’ (1, USNM). New Jersey: same data as lectotype (1, USNM). Ohio: Ross Co. (1, USNM).

This species closely resembles L. fauveli. The antennomeres IV and V are 2× as long as wide in L. crurale and 1.6× times as long in L. fauveli. Males of L. crurale can also be distinguished by the deeper emargination on sternite VIII which is ~ ¼ the depth of the sternite, as opposed to 1/10 as deep in L. fauveli. The female sternite VIII is more conical in L. fauveli than L. crurale.

Figures 35–40. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. 35 L. armatum 36 L. confusum 37 L. crurale 38 L. fauveli 39 L. fulvipenne 40 L. geminum. Scale bars: 1 mm.

Body length 7 mm; body coloration red, appendages light yellow. Gular sutures parallel, widely separate; antennomeres V–VIII 2× as long as wide. Elytra as long as pronotum. Females with paraprocts undivided, apices longer than basal portion; sternite VIII oblong. Male genitalia as in Fig. 37. We were unable to dissect the genitalia of Casey’s female specimens.

USA: IA, NJ, OH.

Lectotype , Lathrobium fauveli Duvivier, herein designated (MCZ): Faded disc / “♂ / [handwritten] L. simplex Lec. / [red] Type 6451 / Lectotype Lathrobium simplex LeConte Desg. Haberski & Caterino.” Lectotype, Lathrobium gravidulum Casey, herein designated (USNM): “Mass / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38124 / [handwritten] gravidulum / Lectotype Lathrobium gravidulum Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium innocens Casey, herein designated (USNM): “Marq / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38126 / [handwritten] innocens / Lectotype Lathrobium innocens Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium neglectum Casey, herein designated (USNM): “RI / CASEY bequest 1925 / [red] TYPE USNM 38125 / [handwritten] neglectum / Lectotype Lathrobium neglectum Casey Desg. Haberski & Caterino.”

Canada: Nova Scotia: Queens Co.: Kejimkujik National Park, 09 May 1999, J. C. Ciegler (1, CUAC). Quebec: MRC de Portneuf: Pont-Rouge, 22 Apr 2023, N. Bédard, sifted from dead leaves in a sandpit (1, NBC). USA: Connecticut: New Haven Co. New Haven (6, USNM). Massachusetts: ‘Mass.’ (1, MCZ); ‘Mass.’ (4, USNM). Michigan: Marquette Co.: Marquette (1, USNM). New Hampshire: Grafton Co.: Downes Brook, Potash Mountain, 05 Jun 2021, A. Haberski, along creek edge (1, CUAC); Coos Co.: Mount Washington 2700’ elev. (1, UNHC); Strafford Co.: Spruce Hole Conservation Area, D. S. Chandler (1, UNHC); Grafton Co.: Hubbard Brook Experimental Forest, D. S. Chandler (1, UNHC). Rhode Island: ‘R. I.’ (1, USNM).

This species closely resembles L. crurale and can be distinguished from that species by the characters discussed in the diagnosis of L. crurale.

Body length 8 mm; body coloration dark red, appendages lighter red. Gular sutures parallel, widely separate; antennomeres V–VIII longer than wide. Elytra as long as pronotum. Females with paraprocts undivided, apices longer than basal portion; sternite VIII conical. Ventral process of aedeagus with distinctive apical tooth (Fig. 38).

Canada: AB, BC, MB, NB, NF, NS, ON, PE, QC, SK (Bousquet et al. 2013). USA: CT, MA, ME, MI, NH, RI, WI (Casey 1905; Newton 2022).

We reduce Lathrobium gravidulum, Lathrobium innocens, and Lathrobium neglectum to synonymy with Lathrobium fauveli, based on the absence of clear distinguishing characters. Lathrobium neglectum and L. innocens were distinguished from L. fauveli based on larger emarginations in male sternite VIII. However, we found no difference in size among species. Lathrobium gravidulum was distinguished based on subtle differences in punctation and the coloration of appendages, but neither are consistent. Examination of the genitalia found no differences in either aedeagi or female terminalia.

Types not examined.

Males have a distinctive, asymmetrical aedeagus that differs from all other Nearctic species (Fig. 39C). Females can be distinguished by the shape of their valvifers (Fig. 39A).

Body length 8 mm; body coloration dark, appendages and mouthparts light red, elytra bicolored with narrow black base, or monochromatic black. Gular sutures parallel; antennomeres V–VII longer than wide. Wing dimorphic, elytra as long or slightly longer than pronotum. Females tergite IX with paraprocts undivided, apical lobes shorter than basal portion in dorsal view; sternite VIII oblong, valvifers and coxites divided (Fig. 39A). Male sternite VIII without patches of dark setae, apical emargination shallow and round (Fig. 39 B). Ventral process of aedeagus asymmetrical in ventral view (Fig. 39C; Assing and Schülke 2012).

Canada: AB, BC, NB, NF, QC (Bousquet et al. 2013).

Native to the Palearctic and adventive in North America. Common in unforested habitats (Assing and Schülke 2012).

Types not examined.

In North America, this species is most similar to L. amplipenne. Males can be distinguished from L. amplipenne, and all other Nearctic species, by their distinctive aedeagus (Fig. 40D), and females can be distinguished by their short gonocoxites, which are only ~ ½ as long as their paraprocts, rather than subequal as in L. amplipenne.

Large species, body length 8–11 mm; body coloration dark, appendages light brown, elytra bicolored with broad black base, rarely solid black. Gular converging, antennomeres V–VII 1.2× as long as wide. Wing dimorphic, elytra approximately as long as pronotum. Females tergite IX with paraprocts undivided, apical lobes shorter than basal portion in dorsal view; sternite VIII with truncate apex; valvifers and coxites fused (Fig. 40A). Male sternite VIII with two longitudinal patches of dark setae in posterior third, apex indistinctly emarginated. Ventral process of aedeagus distinctively shaped with apical tooth (Fig. 40D) (Assing and Schülke 2012).

Canada: BC (Pentinsaari et al. 2019).

Native to the Palearctic and adventive in North America. Common in moist, open habitats (Assing and Schülke 2012). Canadian specimens collected in wetland adjacent to lake (Pentinsaari et al. 2019).

Holotype ♂ (FMNH): “USA: NC: Caldwell Co., 36.1117°N, 81.8068°W, Grandfather Mountain, Calloway Peak X.6.2020, M. Caterino, F. Etzler, A. Haberski, sifted litter.” / “Caterino DNA voucher, Ext. MSC-6239” / “CLEMSON ENT [QR CODE] CUAC000169030”. Paratypes (36, CUAC, FMNH, VMNH): 10: same locality as type, 36.1118°N, 81.8105°W, x.06.2020 (CUAC000112914, CUAC000112915, CUAC000177130, CUAC000177131, CUAC000177132, CUAC000177133, CUAC000177134, CUAC000177135, CUAC000177136, CUAC000177137); 3: same locality as type, 36.0978°N, 81.8293°W, 5370ft., iv.21.2022 (CUAC000177093, CUAC000177094, CUAC000177095); 1: same locality as type, 36.1118°N, 81.8112°W, x.06.2020 (CUAC000177109); 20: same locality as type, 36.1117°N, 81.8088°W, x.06.2020 (CUAC000177110, CUAC000177111, CUAC000177112, CUAC000177113, CUAC000177114, CUAC000177115, CUAC000177116, CUAC000177117, CUAC000177118, CUAC000177119, CUAC000177120, CUAC000177121, CUAC000177122, CUAC000177123, CUAC000177124, CUAC000177125, CUAC000177126, CUAC000177127, CUAC000177128, CUAC000177129); 1: same locality as type, 36.1104°N, 81.8046°W, v.17.2021 (CUAC000177138); 1: same locality as type, 36.1116°N, 81.8117°W, V.17.2021 (CUAC000135036).

North Carolina: Mitchell Co.: Grassy Ridge Bald, 6135’, (36.0985, -82.1791), M.S. Caterino, 08 Jun 2020 (CUAC); Mitchell Co.: Roan High Bluff, 6225–6251’, (36.0931, -82.1453), M.S. Caterino, 15 Aug 2018 (3, CUAC); Mitchell Co.: Roan High Knob, 5756–6286’, (36.1045, -82.1224), M.S. Caterino, 08 Jun 2020 (3, CUAC). Virginia: Smyth Co.: Mt. Rogers, 5699’, Jefferson National Forest (36.6602, -81.5447), M.S. Caterino & P. Marek, 03 Jul 2018 (7, CUAC); Smyth Co.: Mt. Rogers, 5699’, Jefferson National Forest (36.6602, -81.5447), M.S. Caterino & P. Marek, 03 Jul 2018, CUAC000187893, CUAC000187899 (15 larvae, CUAC); Smyth Co.: Mt. Rogers, 5666–5680’, Jefferson National Forest (36.6605, -81.5447), M.S. Caterino & F. Etzler, A. Haberski, 27 Oct 2020 (27, CUAC); Smyth Co.: Mt. Rogers, 5686’, Jefferson National Forest (36.6612, -81.5456), M.S. Caterino, 27 Oct 2020 (3, CUAC); Smyth Co.: Mt. Rogers, Jefferson National Forest (36.657, -81.555), C.W. Harden, 15 Apr 2019 (CUAC); Smyth Co.: Whitetop Mountain, 5503’, Jefferson National Forest (36.6391, -81.6064), M.S. Caterino & P. Marek, 03 Jul 2018 (CUAC); Smyth Co.: Whitetop Mountain, 5436’, Jefferson National Forest (36.6379, -81.6053), M.S. Caterino, 27 Oct 2020 (CUAC); Smyth Co.: Whitetop Mountain, Jefferson National Forest (36.629, -81.596), C.W. Harden, 15 Apr 2019 (CUAC);Grayson Co.: Wilburn Ridge, 5450’, Jefferson National Forest (36.6525, -81.5167), M.S. Caterino & P. Marek, 03 Jul 2018 (2, CUAC).

This species can be distinguished from the closely related L. lividum only by its genitalia. The spines of the internal sac of their aedeagi differ conspicuously (Fig. 7E, F vs Fig. 8D, E). Differences in female genitalia are more subtle, but the gonocoxites of L. islae are narrower at their base. No intermediate forms are known.

Four other species of Nearctic Lathrobium have short elytra and functional eyes, but none are likely to be mistaken for L. islae or L. lividum. Lathrobium brevipenne, L. carolinae, and L. camplyacra are twice as large, lighter in color, and have an overall different gestalt. Lathrobium pallescens has a pale red body color and its eyes are much smaller, 1/8 the lateral length of the head with ~ 30 ommatidia.

Habitus (Fig. 7A). Small species, total body length ~ 4.5 mm long, FL 2.5–3.0 mm long. Coloration: body black; legs, palpomeres, and antennae dark red.

Head subquadrate, as wide as long, widest posteriorly and narrower anterior to eyes; posterior angles slightly rounded; epicranium coarsely punctate, punctures less dense in median dorsal and anterior regions; interstices with strong transversely reticulate microsculpture throughout; head setose throughout, with long macrosetae projecting at posterior corners of head, corners of the eyes, laterally posterior to the eyes, and above the mandible insertions; gular sutures arcuate, widely separate, 1/16 width of head apart at their most proximal point; neck ½ as wide as head. Eyes large and well developed with ~ 95 ommatidia, occupying ¼ lateral length of the head. Antennae moniliform, as long as head and pronotum combined; scape as long as antennomeres II and III combined; antennomeres II–IV elongate, gradually widening so that antennomeres V–IX are as wide as long; apical antennomere longer, subacute.

Pronotum longer than wide, as wide or slightly wider than head; sides parallel; angles rounded; punctures large, spaced one diameter apart, impunctate at midline with a visible line; interstices shiny with a finely punctate microsculpture. Elytra shorter but slightly wider than pronotum, as wide as head, as long as wide; anterior angles somewhat squared, posterior margins sinuate; scutellum round; punctures small, irregularly spaced, most 1–2× their diameter apart; interstices with finely punctate microsculpture. Hindwings vestigial, 0.2 mm long, 1/5 length of elytra. Posterior margin of abdominal tergite VII without palisade fringe.

♂: Sternite VII flattened medially with shallow notch on the posterior margin; posterior margin of sternite VIII with a deep U-shaped notch (Fig. 7D). Aedeagus 1.7 mm long (Fig. 7E, F), ventral process short, not extending much beyond the median foramen posteriorly, lightly sclerotized portion of the median lobe protruding beyond it in lateral view; dorsal plate asymmetrical; internal sac with a single large spine with a characteristic club tip in ventral view.

♀: Sternite VIII slightly oblong with a triangular patch of dense setae at the tip (Fig. 7C); paraprocts divided anteriorly; proctiger conical. sternum IX with valvifers and coxites fused, valvifers narrow at base (Fig. 7B); subgenital plate absent.

First instar larva : Body elongate, ~ 3 mm long; well sclerotized (Fig. 41A); head, thoracic, and abdominal tergites brown, appendages light yellow, intersegmental membrane white, translucent.

Head ovate, widest at stemmata and slightly tapered posteriad (in dorsal view), dorsoventrally flattened, 1.1× as long as wide, dorsal setae as in Fig. 41A; head 2.5× wider than neck, dorsal ecdysial lines bifurcate 1/2 distance between neck and nasale margin; six stemmata present, arranged as in Fig. 41B; anterior margin of nasale (Fig. 41C) with nine blunt teeth pointing anteriorly, one quadrate median tooth with tetradentate anterior edge, a pair of paramedian teeth, and three pairs of lateral teeth; the innermost lateral teeth are small and indistinct; paramedian and lateral teeth armed with nodular setae, and a pair of nodular setae separate median and paramedian teeth; Apotome of gula not reaching tentoral pits.

Antennae (Fig. 41F) length ratio: 1.0:2:3.1:1.6; antennomere I triangular; antennomere II with two pores; antennomere III with three elongate macrosetae, three solenidia, one pore; antennomere IV club-shaped with apical solenidia; sensory appendage 0.9× as long as antennomere IV.

Mandibles (Fig. 41D) long, falciform, serrate along inner margin, with a single seta near the base on the outer ventral edge. Maxilla (Fig. 41D) with cardo triangular, widening from base to apex; stipes quadrate, 1.3× longer than cardo; mala digitiform, tapering toward apex, 0.9× as long as palpomere I, with apical sensory appendages and two pores; palpifer with one seta. Maxillary palpomere length ratios: 1.0:1.2:2.8; palpomere II with two setae; palpomere III with one basal sensory appendage and numerous small apical appendages. Labium with prementum subquadrate, basal portion strongly sclerotized; ligula with elongate membranous apex, twice as long as wide, densely fimbriate, separated from prementum by a distinctly sclerotized transverse strip; palpomere I 1.6× as long as II; palpomere II bearing short sensilla at apex.

Dorsal sclerites of thorax with ecdysial lines along midline of body; prothorax subquadrate, narrowing slightly anteriorly, chaetotaxy as in Fig. 41A; thoracic tergite II and III subequal; abdominal sclerites well sclerotized, with two small pleural sclerites per segment on each side; basal segment of urogomphus 2.6× as long as terminal segment, with seven prominent lateral setae; terminal segment of urogomphus slender, with one short and one long apical seta.

Second instar larva : Second instar (Fig. 42A) resembles first, except as follows. Body larger, ~ 6 mm long. Head subquadrate; dorsal ecdysial lines of the head bifurcate 2/5 distance between nasale margin and neck; median tooth of nasale triangular with serrated edges and a blunt tip (Fig. 42C). Apotome of gula reaching tentoral pits. Antenna (Fig. 42F) length ratios: 1.0:3.5:2.8:1.5; antennomere IV club-shaped with apex 2× as wide as base. Mandible interior margin smooth (Fig. 42D). Maxilla palpomere length ratios: 1.0:1.5:3.3; Labial palpomere I 1.5× II (Fig. 42E); palpomere I distinctly curved; palpomere II bent near apex. Prothorax round. Urogomphi broken off of only known specimen.

Figure 41. 

Lathrobium islae first instar larva A habitus B head in lateral view C nasale D mandible E maxilla F antenna. Scale bars: 1 mm (A); 500 μm (B); 100 μm (B, D); 250 μm (E, F).

Figure 42. 

Lathrobium islae second instar larva A habitus B head in lateral view C nasale D mandible E maxilla F antenna. Scale bars: 1 mm (A, B); 250 μm (C); 500 μm (D, E, F).

Figure 43. 

Distribution of Lathrobium islae (circle), L. lividum (star).

Named in honor of Isla Haberski, daughter of the first author, who was born during the preparation of this manuscript.

Lathrobium islae inhabits spruce-fir forests above 1500 m in the Grayson Highlands, Roan Highlands, and on Grandfather Mountain (Fig. 43). It can be collected from leaf litter but is most common on boulders beneath bryophyte mats. It has not been found in spruce-fir forests south of the French Broad River basin, where its microhabitat is inhabited by L. smokiense and L. balsamense. Adults collected Jul–Sep. Larvae collected Mar–Jul.

Lathrobium islae was not monophyletic in our COI phylogeny and ASAP identified five genetic partitions. Given this degree of genetic variation, populations outside the type locality might also differ in minor ways morphologically, perhaps in characters not yet evaluated. Larvae were associated with adults by DNA barcoding.

Lectotype , Lathrobium leconteanum Scheerpeltz, herein designated (MCZ): Faded disc / “♂ ♀ / [handwritten] L. concolor Lec. / [red] Type 6450 / Lectotype Lathrobium concolor LeConte Desg. Haberski & Caterino.”

USA: Indiana: ‘Ind.’ (1, USNM). New Hampshire: Coos Co.: Mount Washington (1, UNHC); Grafton Co.: Hubbard Brook Experimental Forest, D. S. Chandler (1, UNHC).

This species is similar in appearance to L. washingtoni but differs in having elongate antennomeres. Males are otherwise difficult to tell apart, even in the primary and secondary sexual characters. Lathrobium leconteanum has four spines on the internal sac of the aedeagus whereas L. washingtoni has two. Females are more easily differentiated because L. leconteanum has an undivided tergite IX and L. washingtoni has tergite IX fully divided.

Body length 7 mm; body coloration dark red, appendages lighter. Gular sutures parallel, widely separate; antennomeres V–VII longer than wide. Elytra 1.2× longer than pronotum. Females with paraprocts undivided, apices 1.3× as long as basal portion; sternite VIII conical with small apical notch. Genitalia as in Fig. 44.

Canada: ON, NF (Bousquet et al. 2013). USA: IN, NH.

Types not examined.

This species is most similar to L. fulvipenne but can be distinguished by the ventral process of the aedeagus, which lacks an apical tooth and is nearly symmetrical in ventral view (Fig. 45C).

Body length 8 mm; body coloration dark, appendages light brown, elytra usually bicolored with narrow black base. Gular sutures parallel; antennomeres V–VII longer than wide. Elytra as long as pronotum or slightly shorter. Female tergite IX with apical lobes of paraprocts longer than continuous anterior portion in dorsal view; sternite VIII with truncate apex. Ventral process of the aedeagus strongly deflexed, distal tip lying beyond median foreman in lateral view (Fig. 45C).

Canada: ON (Pentinsaari et al. 2019).

Native to the Palearctic and adventive in North American. Found in forest and riparian habitats (Pentinsaari et al. 2019).

Holotype ♂ (FMNH): “USA: NC: Yancey Co., 35.7643°N, 82.2629°W, Mt. Mitchell SP, Mt. Mitchell, 6556’, ix.07.2021, M. Caterino & E. Recuero, sifted litter.” / “Caterino DNA voucher, Ext. MSC-7880, Morphosp. MM.B.318” / “CLEMSON ENT [QR CODE] CUAC000135757”. Paratypes (40): 5 (CUAC): same locality as type, 35.7643°N, 82.2633°W, X.06.2020 (CUAC000169022, CUAC000169023, CUAC000177098, CUAC000177099, CUAC000177100); 9 (CUAC): same locality as type, 35.7643°N, 82.2633°W, 6589ft, ix.07.2021 (CUAC000169022, CUAC000169023, CUAC000177169, CUAC000177170, CUAC000177171, CUAC000177172, CUAC000177173, CUAC000177174, CUAC000177175); 1 (CUAC): same locality as type, 35.7644°N, 82.2641°W, V.15.2018 (CUAC00079253); 5 (MCZ): “Black Mts. N. C., Mt. Mitchell 5000–6711 ft, IX.05.1930, Darlington.”; 2 (CUAC): “USA: NC: Yancey Co., 35.7798°N, 82.2599°W, Mount Mitchell State Park, Big Tom, 6586’, v.15.2018, M. Caterino, sifted litter.” (CUAC000048570); 10 (CUAC) same locality, 35.7795°N, 82.2596°W, 6554’, ix.07.2021, M. Caterino (CUAC000157555, CUAC000157567, CUAC000157568, CUAC000172501, CUAC000172505, CUAC000172506, CUAC000172509, CUAC000172511, CUAC000172513, CUAC000172514); 2 (CUAC) “USA: NC: Yancey Co., 35.8525°N, 82.2468°W, Pisgah National Forest, Celo Knob, 6284’, vi.15.2020, M. Caterino, sifted litter” (CUAC000004036, CUAC000169024); 4: “USA: NC: Yancey Co., 35.8524°N, 82.2485°W, Pisgah National Forest, Celo Knob, 6300’, x.19.2021, M. Caterino, E. Recuero & A. Haberski, sifted litter” (CUAC000177101, CUAC000177102, CUAC000177103, CUAC000177104); 4: “USA: NC: Yancey Co., 35.8527°N, 82.2487°W, Pisgah National Forest, Celo Knob, 6294’, x.19.2021, M. Caterino, E. Recuero & A. Haberski, sifted litter” (CUAC000177105, CUAC000177106, CUAC000177107, CUAC000177108); 3: “USA: NC: Yancey Co., 35.8522°N, 82.2485°W, Pisgah National Forest, Celo Knob, 6300’, vi.15.2020, M. Caterino & F. Etzler, sifted litter” (CUAC000177145, CUAC000177146, CUAC000177147); 2: “USA: NC: Yancey Co., 35.8523°N, 82.2486°W, Pisgah National Forest, Celo Knob, 6300’, vi.15.2020, M. Caterino & F. Etzler, sifted litter” (CUAC000177148, CUAC000177149); 2 (CUAC) “USA: NC: Yancey Co., 35.8525°N, 82.2468°W, Pisgah National Forest, Celo Knob, 6284’, vi.15.2020, M. Caterino, sifted litter” (CUAC000004036, CUAC000169024); 2 (CUAC) “USA: NC: Yancey Co., 35.7782°N, 82.2610°W, Mount Mitchell State Park, Mt. Craig, 6550’ v.15.2018, M. Caterino, sifted litter” (CUAC000003088, CUAC000169028).

Figures 44–49. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. 44 L. leconteanum 45 L. lineatocolle 46 L. pedale 47 L. praelongum 48 L. rhodeanum 49 L. simile. Scale bars: 1 mm.

North Carolina: Buncombe Co.: Base of Mt. Mitchell, 5413’, Blue Ridge Parkway, A. Smetana, 03 Jun 1986 (5, CNC); Yancey Co.: Mt. Mitchell, 6561–6679’, Mount Mitchell State Park, A. Smetana, 04 Jun 1986 (6, CNC); Buncombe Co.: Craggy Dome, 5696–5845’ 13 Sep 2022 (4, CUAC).

This species can be distinguished from the closely related L. islae only by its genitalia. The spines of the internal sac of their aedeagi differ conspicuously (Fig. 8D, E vs Fig. 7E, F), but differences in female genitalia are more subtle. The gonocoxites of L. islae are narrowed at the base, but not in L. lividum. No intermediate forms are known.

External morphology is identical to that of L. islae. It differs only in genitalia.

♂: Aedeagus (Fig. 8D, E) with ventral process longer, nearly reaching the end of the median lobe; dorsal plate small and blade-like; the internal sac with a single large, curved spine that projects above the median lobe.

♀: Gonocoxite width subequal from base to apex (Fig. 8A).

The specific name is Latin, meaning bruised, in reference to its dark coloration.

Lathrobium lividum might have the smallest range of any Nearctic Lathrobium. It is endemic to spruce-fir forests above 1500 m elevation in the Black Mountains and Craggy Mountains of North Carolina (Fig. 43). Collected Jul–Sep.

Lectotype , Lathrobium pedale LeConte, herein designated (MCZ): “La. / ♂ / [handwritten] L. pedale Lec. / [red] Type 6454 / Lectotype Lathrobium pedale LeConte Desg. Haberski & Caterino.”

USA: North Carolina: Swain Co.: Hazel Creek, Great Smoky Mountains National Park, 18 Jul 2003, S. L. Staines, C. Ware (1, LSAM). South Carolina: Colleton Co.: Canadys, 30 Jul 1993, J. C. Ciegler (1, CUAC); Kershaw Co.: Wateree Floodlands Memorial Forest, 13 Apr, 2021, C. Harden, pine stump/flood debris (1, CUAC). Virginia: Botetourt Co.: Solitude Swamp, 28 Jun 2018, C. Harden, deep oak litter on swamp margin (1, CUAC).

This species closely resembles L. amplipenne, L. armatum, and L. praelongum in external morphology, but differs in the primary and secondary sexual characters. Males of L. pedale have a large emargination on sternite VIII, where the aforementioned species have small emarginations or none at all. They also lack a dorsal plate of the aedeagus. Females differ from the three aforementioned species by having valvifers and coxites fully divided.

Large species, body length 9 mm; body coloration dark red, appendages lighter red or yellow. Gular sutures converging, nearly touching posteriorly; antennomeres V–VII as wide as long. Elytra as long as pronotum. Females with paraprocts undivided, apices shorter than basal portion; sternite VIII weakly oblong. Genitalia as in Fig. 46.

USA: LA, NC, SC, VA.

Lectotype , Lathrobium praelongum Casey, herein designated (USNM): “Coll J B: / CASEY bequest 1925 / [handwritten] praelongum / [red] TYPE USNM 38113 / Lectotype Lathrobium praelongum Casey Desg. Haberski & Caterino.”

USA: Maryland: Allegany Co.: Little Orleans, 05 Jun 2021, A. Deczynski (1, CUAC). North Carolina: Swain Co.: Hazel Creek Great Smoky Mountains National Park, 18 Jul 2003, S. L. Staines, C. Ware (2, LSAM). Virginia: Highland Co.: Bullpasture River, 02 Jun 2019, C. Harden, streamside gravel/cobble/sand (1, CUAC); Shenandoah Co.: Passage Creek near Buzzard Rock, 18 Apr 2016, C. Harden, under stones, wet sandy soil (1, CUAC); Shenandoah Co.: Elizabeth Furnace Recreational Area, Rte 619 Mudhole Gap trail, 09 Jan 2016, C. Harden (1, CUAC); Shenandoah Co.: George Washing National Forest, Signal Knob trailhead, 25 Oct 2017, C. Harden, moist ditch in floodplain (1, CUAC); Appomattox Co.: Holiday Lake State Park, 15 Jun 2017, C. Harden (1, CUAC); Bath Co.: Whites Cave, 15 Oct 2020, C. Harden (1, CUAC).

This species closely resembles L. amplipenne, L. armatum, and L. pedale in external morphology. Males are readily distinguished by the uniquely shaped ventral process of the aedeagus that is twice as long as the median lobe. Females are more challenging, but they have shorter paraprocts than the aforementioned species, and denser pubescence on their gonocoxites.

Large species, body length 9 mm; body coloration dark, appendages paler red, elytra bicolored. Gular sutures converging, nearly touching posteriorly; antennomeres V–VII as wide as long. Elytra at least as long as pronotum. Females with paraprocts undivided, apices shorter than basal portion, ~ 0.7× as long; sternite VIII weakly oblong. Characteristic aedeagus (Fig. 47).

USA: IL, MD, NJ, NC, VA.

Lectotype , Litolathra rhodeana Casey, herein designated (USNM): “R. I. / ♂ / CASEY bequest 1925 / [red] TYPE USNM 38127 / [handwritten] rhodeana / Lectotype Litolathra rhodeana Casey Desg. Haberski & Caterino.” Lectotype Litolathra semirubida Casey, herein designated (USNM): “R.I. / CASEY bequest 1925 / [red] TYPE USNM 38128 / [handwritten] semirubida / Lectotype Litolathra semirubida Casey Desg. Haberski & Caterino.”

USA: Massachusetts: ‘Mass’ (1, USNM). New York: ‘N. Y.’ (1, USNM). Rhode Island: ‘R. I.’ (2, USNM). South Carolina: Hampton Co.: Bluff Lake, Webb Wildlife Management Area, 29 Apr 2017, J. C. Ciegler, UV light (1, CUAC). Virginia: Sussex Co.: Chub Sandhill Natural Area Preserve, 24 Sep 2017, C. Harden, litter from dark moist woods near pool (2, CUAC); Botetourt Co.: Solitude Swamp, 28 Jun 2018, C. Harden, deep oak litter on swamp margin, exposed mounds (5, CUAC).

This species closely resembles L. confusum. They differ in the lengths of the hind tarsomeres which are longer in L. rhodeanum than in L. confusum. Females are otherwise difficult to tell apart, but males are easily identified by the elongate spine in the internal sac of the aedeagus, which is unique.

Body length 7 mm. Body coloration red throughout. Females with paraprocts undivided, apices 2.7× longer than basal portion, sternite VIII oblong. Elytra longer and wider than pronotum. Antennomeres V–VII 2× as long as wide. Aedeagus with characteristic elongate structures of the internal sac (Fig. 48).

Canada: QC (Newton 2022). USA: MA, NY, RI, SC, VA.

We reduce Lathrobium semirubidum to synonymy with Lathrobium rhodeanum. Lathrobium semirubidum was described from a single specimen that subtly differs from L. rhodeanum in body coloration, punctation, and head width, but these differences do not exceed the intraspecific variation observed in longer series of other Lathrobium. The lectotypes of both species were collected from the same location, on the same day, and their aedeagi are indistinguishable.

Lectotype , Lathrobium simile LeConte, herein designated (MCZ): Pink disc / “♂ / [handwritten] L. simile Lec. / [red] Type 6449 / Lectotype Lathrobium simile Leconte Desg. Haberski & Caterino.”

Canada: Manitoba: Aweme (4, USNM). USA: Massachusetts: ‘Mass’ (4, USNM). New Hampshire: Strafford Co.: Spruce Hole Conservation Area, D. S. Chandler (1, UNHC); Grafton Co.: Hubbard Brook Experimental Forest, D. S. Chandler (1, UNH). New Jersey: ‘N. J.?’ (1, USNM). New York: ‘N. Y.’ (3, USNM). Pennsylvania: Philadelphia, July 1928 (1, CNC). Rhode Island: ‘R. I.’ (6, USNM). Vermont: White River Junction, 29.V.1979, E.J. Kiteley (4, CNC).

This species can be difficult to distinguish from L. sparsellum. Lathrobium simile has elongate antennomeres, whereas L. sparsellum has subquadrate antennomeres. Additionally, L. simile has a marginally thicker neck. Males can be further distinguished by the emargination on sternite VIII. The emargination of L. simile is wider than deep and there is a patch of thick black setae below. The emargination of L. sparsellum is deeper than wide and there are no thick black setae. Females are easily distinguished by the shape of the proctiger, which is conical in L. simile but pointed in L. sparsellum, a unique characteristic of that species.

Body length 8 mm; body coloration red, appendages light yellow. Gular sutures parallel, widely separate; antennomeres V–VII longer than wide. Elytra as long as pronotum. Females with paraprocts divided; sternite VIII oblong. Male sternite VIII with wide, shallow emargination and two vertical rows of thick black setae (Fig. 49B). Genitalia as in Fig. 49.

Canada: MB, NB, NS, ON, QC (Bousquet et al. 2013). USA: CT, DC, IN, MA, ME, NH, NJ, NY, PA, RI, VT (Newton 2022).

Lectotype , Lathrobium sparsellum Casey, herein designated (USNM): “Winnipg. Man. / CASEY bequest 1925 / [red] TYPE USNM 38120 / [handwritten] sparsellum / Lectotype Lathrobium sparsellum Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium obtusum Casey, herein designated (USNM): “Mass/ CASEY bequest 1925 / [red] TYPE USNM 38119 / Lectotype Lathrobium obtusum Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium postremum Casey, herein designated (USNM): “R.I. / CASEY bequest 1925 / [red] TYPE USNM 38123 / [handwritten] postremum / Lectotype Lathrobium postremum Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium rigidum Casey, herein designated (USNM): “R.I. / CASEY bequest 1925 / [red] TYPE USNM 38122 / [handwritten] rigidum / Lectotype Lathrobium rigidum Casey Desg. Haberski & Caterino.”

Canada: ‘Can’ (1, USNM). Quebec: MRC des Deux-Montagnes: Parc National d’Oka, 06 May 2023, R. Vigneault, handpicked near beach (1, NBC); same data, except white tulle interception trap in composting site (1, NBC). USA; Connecticut: New Haven Co.: New Haven (1, USNM). Massachusetts: ‘Mass’ (2, USNM). New Hampshire: Strafford Co.: Spruce Hole Conservation Area, D. S. Chandler (1, UNHC); Rhode Island: ‘R. I.’ (4, USNM).

This species closely resembles L. simile but can be differentiated as described under the diagnosis for L. simile.

Body length 8 mm; body coloration dark, appendages lighter red. Gular sutures parallel, widely separate; antennomeres V–VII as long as wide. Elytra as long as pronotum. Females with paraprocts divided; proctiger narrow; sternite VIII weakly oblong. Male sternite VIII with narrow, deep emargination. Genitalia as in Fig. 50.

Canada: AB, MB, NB, NF, NS, ON, QC (Bousquet et al. 2013). USA: CT, MA, ME, NH, NY, RI, VT (Newton 2022).

We reduce Lathrobium obtusum, Lathrobium postremum, and Lathrobium rigidum to synonymy with Lathrobium sparsellum based on the inaccuracies of the original descriptions and the inability to find alternative distinguishing characters. Lathrobium postremum and L. rigidum were differentiated from L. sparsellum based on their elytra being shorter than the pronotum, as opposed to subequal as in L. sparsellum. However, we measured Casey’s specimens and found the elytra to be subequal or slightly longer than the pronotum in all three species.

Lathrobium obtusum was distinguished from L. sparsellum primarily based on the gular sutures being “moderately separated and feebly converging” as opposed to “widely separated, almost straight” in L. sparsellum (Casey 1905). However, we could not see a difference in suture shape, and sutures in both species were approximately equidistant. We examined the genitalia of all four species and found no morphological differences in males or females.

Lectotype Lathrobium spissicorne Casey, herein designated (USNM): “Mass / CASEY bequest 1925 / [red] TYPE USNM 38111 / [handwritten] spissicorne / Lectotype Lathrobium spissicorne Casey Desg. Haberski & Caterino.”

USA: Massachusetts: ‘Mass’ (1, USNM); ‘Mass’ (1, MCZ). Michigan: Wayne Co.: Detroit, Oct (1, USNM).

Lathrobium spissicorne can be distinguished from all other Nearctic Lathrobium by unique primary and secondary sexual characters. The male sternite VIII has a scalloped emargination, and the dorsal plate of the aedeagus bends over the top of the ventral process. In females, the inner margin of the gonocoxites is broad and distinctively arched.

Body length 7 mm; body coloration dark red throughout. Gular sutures parallel, widely separate; antennomeres V–VII as wide as long. Elytra longer than pronotum. Female sternite VIII weakly oblong. Genitalia as in Fig. 51.

Canada: NB, ON, QC, PE (Bousquet et al. 2013). USA: MA, MI.

Lectotype , Lathrobium washingtoni Casey, herein designated (USNM): “N. H. / ♂ / [red] TYPE USNM 38121 / CASEY bequest 1925 / [handwritten] washingtoni / Lectotype Lathrobium washingtoni Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium illini Casey, herein designated (USNM): “Illinois / CASEY bequest 1925 / [handwritten] illini / [red] TYPE USNM 38118 / Lectotype Lathrobium illini Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium longiventre Casey, herein designated (USNM): “Bayfld / CASEY bequest 1925 / [handwritten] longiventre / [red] TYPE USNM 38115 / Lectotype Lathrobium longiventre Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium picescens Casey, herein designated (USNM): “N.H. / CASEY bequest 1925 / [handwritten] picescens / [red] TYPE USNM 38116 / Lectotype Lathrobium picescens Casey Desg. Haberski & Caterino.” Lectotype, Lathrobium vancouveri Casey, herein designated (USNM): “Br.C / CASEY bequest 1925 / [handwritten] vancouveri / [red] TYPE USNM 38117 / Lectotype Lathrobium vancouveri Casey Desg. Haberski & Caterino.”

Figures 50–53. 

Lathrobium terminalia A female terminalia B male sternite VIII C aedeagus in ventral view D aedeagus in lateral view. 50 L. sparsellum 51 L. spissicorne 52 L. washingtoni 53 L. debile. Scale bars: 1 mm.

Canada: British Columbia: Terrace, Hippisley (1, MCZ). Newfoundland: ‘N’f’land’ 19–24 Jul 1907 (1, MCZ). USA: Alaska: Fairbanks North Star Borough: Nome Creek, 11 Jun 2018, R. Nowicki (1, UAM). Minnesota: ‘Min.’ (2, USNM). New Hampshire: ‘N. H.’ (1, USNM); Coos Co.: Mount Washington (1, MCZ); Grafton Co.: Woodstock, White Mountains (1, USNM). Wisconsin, Bayfield Co. Bayfield (1, USNM).

This species is similar in appearance to L. leconteanum and can be differentiated as discussed in the diagnosis of L. leconteanum.

Body length 6–7 mm; body coloration dark red, appendages lighter red. Gular sutures, widely separate, converging slightly posteriorly; antennomeres V–VIII as wide as long. Elytra as long as pronotum. Females with paraprocts divided; sternite VIII strongly oblong, tip 1/3 width of base. Genitalia as in Fig. 52.

Canada: AB, BC, MB, NB, NF, NS, NT, ON, QC, SK (Bousquet et al. 2013). USA: AK, ID, IL, MN, MT, NH, WI (Newton 2022).

We reduce Lathrobium illini, Lathrobium longiventre, Lathrobium picescens, and Lathrobium vancouveri to synonymy with Lathrobium washingtoni, because the original diagnoses were based on a single inaccurate character. All four of the herein synonymized species were distinguished from L. washingtoni by having the middle joints of the antennae not longer than wide, as opposed to “elongate” (Casey 1905). We measured the fifth antennomeres of each species and found the ratio of length to width varied within and between species from 1.1 to 1.4× as long as wide, making this character useless for diagnosis. We examined the genitalia and found no differences among species in males or females.

Subgenus Lathrolepta Casey, 1905: 72.

Lectotype , Lathrobium debile LeConte, herein designated (MCZ): “Mic. / [handwritten] 463 / [handwritten] L. debile Lec. / Lectotype Lathrobium debile LeConte Desg. Haberski & Caterino.”

Canada: Ontario: ‘Ont. Can.’ (1, USN). USA: Indiana: ‘In.’ (1, USNM). Massachusetts: ‘Mass,’ Jul 1903, J. Blanchard (1, MCZ); ‘Mass’ (5, USNM). Michigan: ‘Mic.’ (1, USNM). New Hampshire: Grafton Co.: Downes Brook, Potash Mountain, 05 Jun 2021, A. Haberski (1, CUAC); Belknap Co.: Lower Gilmanton, 23 Apr 1982, D. S. Chandler (6, UNHC); Chesire Co.: Rhododendron State Park, 22 Apr 1982, D. S. Chandler, sifted rotten spruce & fir logs (4, UNHC); Hillsborough Co.: Miller State Park, 22 Apr 1982, D. S. Chandler, oak litter (2, UNHC); Strafford Co.: Spruce Hole Conservation Area, 3 mi SW Durham, 02 Jul 1987, litter near bog (2, UNHC). New York: ‘N. Y.’ (1, USNM).

Lathrobium debile differs from all other described species of Nearctic Lathrobium in its small size and diverging gular sutures. However, it resembles members of the sibiricum group, which may have undescribed diversity in Alaska and Northwest Territories. Species in the sibiricum group lack a dorsal plate on the aedeagus and have a sclerotized ring-like structure on the membranous endophallus. Lathrobium debile has a dorsal plate and lacks the ring-like structure.

Extremely small species, body length 3.5–4 mm; coloration reddish, appendages lighter. Gular sutures divergent (Fig. 1D). Antennae short, antennomeres as long as wide. Female sternite VIII oblong. Genitalia as in Fig. 53.

Canada: ON, NB, QC (Bousquet et al. 2013). USA: IA, IN, MA, MI, NH, NY (Newton 2022).

Holotype (MCZ): “Capron 15.4. Fla / 741 / [handwritten] L. parcum Lec. / [red] Type 6458.”

This species is transferred to Pseudolathra based on the protibia not being expanded with protibial combs in lateral view (Żyła et al. 2020).

Lectotype , Lathrobiopsis texana Casey, herein designated (USNM): “Tex. / CASEY bequest 1925 / [red] TYPE USNM 38120 / [handwritten] Lathrobiopsis texanum Csy / Lectotype Lathrobiopsis texana Casey Desg. Haberski & Caterino.”