Ligidium enotahensis Recuero & Caterino, 2025, sp. nov.

Ligidium enotahensis sp. nov. urn:lsid:zoobank.org:act: CF5E1EE6-9001-45DA-9DB2-5DE45CA56D20 Figs 2–3 Ligidium sp. 1 – Recuero & Caterino 2024: table 1. Diagnosis Ligidium enotahensis sp. nov. can be diagnosed morphologically based on the shape on the male pleopod 2 endopodite, showing a squarish tip with no excrescence, projection, or notch, and on the very broad male pleopod 1 endopodite projection. It also can be identified from all other Appalachian species based on molecular data, representing a distinct evolutionary lineage. Etymology From the Cherokee Enotah, a name of the mountain where the species is described, and the Latin suffix ‘ -ēnsis ’, forming an adjective meaning ‘from Enotah’. Material examined Holotype USA – Georgia • ♂; Towns Co., Brasstown Bald; 34.8763° N, 83.8107° W; 1377 m a.s.l.; 17 Nov. 2020; M. Caterino and A. Haberski leg.; GenBank no: OR172584 (Cox1); USNM, CUAC000138051. Other material examined USA – Georgia • 3 imm.; same data as for holotype; CUAC000171312 to CUAC000171314. Description Body length of holotype 5.3 mm, body width (at pereonite 4) 2.6 mm. Color of holotype in ethanol (Fig. 2) dorsally brown with large whitish patches on dorsal surface, a dark brown longitudinal medial stripe running from pereonite 1 to telson, epimera dark brown with a large white patch; head, antennae and uropods dark brown, pereopods and pleopods lighter brown. Immatures much lighter and without longitudinal stripe. Antennule (Fig. 3G) three-segmented; first segment about 2 times as long as wide, with 3 strong spiniform setae on its distal border; second segment slender, about 4 times as long as wide, also bearing 3 strong spiniform setae on the distal border; third segment small, with round apex and a single seta. Antennae (Fig. 3F) with 5 segmented peduncle, relative size of antennomeres 5>4>3>2>1; antennal flagellum with 11 articles. Dactylus of pereopods with outer claw longer than inner one; no sexual dimorphism observed in pereopods 1 (Fig. 3H) and 7 (Fig. 3I). Male pleopod 1 endopodite (Fig. 3A) with broad, squarish projection bearing 3 strong, blunt setae, 1.4 times as long as endopodite. Pleopod 1 exopodite (Fig. 3B) with a flat caudal margin bearing 3 strong, blunt setae, 0.7 times as long as exopodite. Male pleopod 2 exopodite (Fig. 3C) 2 times as wide as long; inner and most part of frontal margin with dense, hairy setation, as in outer caudal corner. Male pleopod 2 endopodite (Fig. 3D–E) with squared tip showing a ventral oblique line of small, poorly defined denticles along the interior corner; inner margin with minute spiniform setae, no spines at the base. Telson (Fig. 2) with caudal margin obtusely produced. Uropod (Fig. 3J) with exopodite broken, endopodite about 1.5 times as long as basipodite; in the examined immatures endopodite 1.5–1.6 times as long as exopodite. Distribution The species is so far only known from its type locality, near the southern extreme of the southern Appalachian Mountains (Fig. 2). All specimens were collected in mixed forest leaf litter samples. Remarks Ligidium enotahensis sp. nov. corresponds with Ligidium sp. 1 in Recuero & Caterino (2024a). This new species is closely related to L. protuberans sp. nov. and L. schultzi sp. nov., but they can easily be identified based on the shape of male pleopod 2 endopodite, by lacking the conspicuous projection present in L. protuberans, or the marked notch typical of L. schultzi. Ligidium enotahensis also presents a much broader projection of male pleopod 1 endopodite. All three gene fragments analyzed are informative to identify this species, with high genetic p-distances for Cox1, and low in the conserved NaK and 28S fragments (Supp. file 1), forming a reciprocally monophyletic clade with respect to either of the other two in all cases.