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

Type material.

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.

Other material.

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

Diagnosis.

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.

Description.

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.

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

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.

Etymology.

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

Distribution and ecology.

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 Lathrobium Apteralium Casey, 1905: 70.

Figures

Figure 18. Distribution of Lathrobium lapidum (star), L. shermani (triangle), L. solum (square), L. thompsonorum (circle)

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.

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).