Ligidium whiteoak sp. nov.

urn:lsid:zoobank.org:act: CAB4ACD2-999C-4C0A-9BD7-A196E4B4EBDF

Figs 12–13

Ligidium sp. 5 – Recuero & Caterino 2024: table 1 (in part).

Diagnosis

Ligidium whiteoak sp. nov. is diagnosed from other Appalachian species by the presence in the male pleopod 2 endopodite of a broad excrescence, almost as broad as the endopodite stem, rising dorsally and medially from the caudal margin of the tip and projecting caudally and slightly outwards. It also can be identified from all other Appalachian species based on molecular data, representing a distinct evolutionary lineage.

Etymology

A noun in apposition, in reference to the species type locality.

Material examined

Holotype

USA – Tennessee • ♂; Blount Co., Great Smoky Mountains N.P., Whiteoak Sink area; 35.6362° N, 83.7412° W; 536 m a.s.l.; 27 Oct. 2021; M. Caterino, A. Haberski and P. Wooden leg.; GenBank no: OR169835 (Cox1); USNM, CUAC000171267.

Paratypes

USA – Tennessee • 3 ♂♂; same data as for holotype; CUAC000171268, CUAC000180800, CUAC000180801 • 5 ♀♀; same data as for holotype; CUAC000171269 to CUAC000171273.

Description

Body length of males 4.9–5.5 mm, of females 4.9–5 mm; width (at pereonite 4) of males 2.3–2.5, of females 2.4–2.6 mm. Color in ethanol (Fig. 12) dorsally brown to dark brown with off-white and greenish spots, a conspicuous dark brown longitudinal medial stripe running from pereonite 1 to pereonite 7, more or less broken with light spots in the caudal margin of pereonites; not all pereonites with darker transverse bands; epimera brown and off-white, with large white spots at the base; pleonites with a pair of lateral off-white spots, medially brown sometimes with off-white spots; telson with two white spots laterally, and a white anchor-shaped spot; head marbled brown; antennae dark brown with large white spots in basal segments and a white setae bundle in the flagellum; uropod brown, dorsally with inner part of basipodite white; pereopods brown and white, pleopod exopodites brown. Antennule (Fig. 13G) three-segmented; first segment about 1.7–1.8 times as long as wide, 3 spiniform setae in its distal border; second segment about 2.6–2.7 times as long as wide, also bearing 3 strong spiniform setae in the distal border; third segment with rounded apex and up to 3 setae. Antennae (Fig. 13F) with 5 segmented peduncle, relative size of antennomeres 5>4>3>2>1; antennal flagellum with 10–11 articles. Dactylus of pereopods with outer claw longer than inner one; no sexual dimorphism observed in pereopods 1 (Fig. 13H) and 7 (Fig. 13I). Pereopod 7 ischium broadened medially. Male pleopod 1 endopodite (Fig. 13A) with narrow projection truncated distally, bearing 2–3 strong, blunt setae, about as long as endopodite; most part of caudal and inner margins with pilose setae. Pleopod 1 exopodite (Fig. 13B) with rounded caudal margin bearing 2–3 strong, blunt setae, 0.6–0.7 times as long as exopodite; external margin with 3–4 short setae. Male pleopod 2 exopodite (Fig. 13C) 1.8–2 times as wide as long; inner and most part of frontal margin with dense, hairy setation, as in outer caudal corner; caudal margin convex, with 3–4 short, but strong setae. Male pleopod 2 endopodite (Fig. 13D–E) with narrow, rounded tip, bearing a soft, long excrescence rising medially, almost as broad as the stem; inner margin with minute spiniform setae. Telson (Fig. 12) with caudal margin obtusely produced, subtriangular. Uropod (Fig. 13J) with endopodite 1.4–1.5 times as long as exopodite when not broken, and about 2 times as long as basipodite.

Distribution

The species is known only from its type locality, at low elevations near the western edge of the Great Smoky Mountains (Fig. 12). All studied specimens have been collected in moist leaf litter from deciduous forest.

Remarks

Ligidium whiteoak sp. nov. corresponds with one of the two lineages referred to as Ligidium sp. 5 in Recuero & Caterino (2024a). See remarks for Ligidium pacolet sp. nov.