Lathrobium (Abletobium) hardeni Haberski & Caterino, 2024

Haberski, Adam & Caterino, Michael S., 2024, A review of Nearctic Lathrobium (Coleoptera, Staphylinidae), with revision and descriptions of new flightless species from the mountains of the southeastern U. S., ZooKeys 1198, pp. 193-277 : 193

Lathrobium (Abletobium) hardeni Haberski & Caterino sp. nov.

Type material.

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).

Other material.

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) .

Diagnosis.

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.

Description.

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.

♂: 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.

Etymology.

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.

Distribution and ecology.

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.

Figures

Figure 13. Distribution of Lathrobium absconditum (triangle), L. Lathrobium balsamense (square), L. hardeni (star), L. smokiense (circle).

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.

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).

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).