Ligidium protuberans Recuero & Caterino, 2025, sp. nov.
Creators: name: Recuero, Ernesto
name: Caterino, Michael S.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Ligiidae
Ligidium
Ligidium protuberans

description: Ligidium protuberans sp. nov.
urn:lsid:zoobank.org:act: 65FAB813-B5FB-4865-9F36-925FC2C1DCA2
Figs 6–7
Ligidium sp. 3 – Recuero & Caterino 2024: table 1.
Diagnosis
This new species is characterized by a male pleopod 2 endopodite distally broadened, with rounded tip presenting a short, squarish projection on its distal margin. It also can be identified from all other Appalachian species based on molecular data, representing a distinct evolutionary lineage.
Etymology
From the latin ‘ protubero ’, meaning ‘protuberance’, referring to the characteristic projection in the male pleopod 2 endopodite.
Material examined
Holotype
USA – North Carolina • ♂; Swain Co., Great Smoky Mountains N.P., Payne Creek at Lakeshore Trail; 35.4855° N, 83.8028° W; 553 m a.s.l.; 12 Apr. 2022; M. Caterino, E. Recuero, A. Haberski and P. Wooden leg.; GenBank no: OR169915 (Cox1); USNM, CUAC000171349.
Paratypes
USA – South Carolina • 1 ♂; Pickens Co., Chimney Top Gap; 35.0644° N, 82.7953° W; 781 m a.s.l.; 23 Mar. 2023; C.W. Harden leg.; CUAC000177090 • 1 ♀; same data as for preceding; CUAC000177089 • 1 ovi ♀; same data as for preceding; CUAC000177088.
Other material examined
USA – North Carolina • 2 ♀♀; Macon Co., Nantahala N.F., Van Hook Glade Campground; 35.0783° N, 83.245° W; 1006 m a.s.l.: 21 Apr. 2022; S. Payne leg.; CUAC000171316, CUAC000171317 • 1 ♀; Clay Co., Nantahala N.F., Tusquitee Bald; 35.1467° N, 83.7146° W; 1262 m a.s.l.; 1 Sep. 2020; M. Caterino and F. Etzler leg.; CUAC000138058.
Description
Body length of males 6.3–6.5 mm, of females 6.8–8.6 mm; width (at pereonite 4) of males 2.8–3, of females 3.3–4.6 mm. Color in ethanol (Fig. 6) dorsally marbled brown and white, with a conspicuous dark brown longitudinal medial stripe running from pereonite 1 to pereonite 7; caudal margin of pereonites with no defined dark brown bands; epimera brown with large white spots in the outer surface an at the base; pleonites brown to dark brown with conspicuous white spots; telson with two large white spots laterally, and a white anchor-shaped spot caudally; head marbled brown and white, white above the eyes; antennae brown with white spots in basal segments and a white setae bundle in the flagellum; uropod brown with iner part of basipodite white; pereopods brown and white, pleopods mostly white. Antennule (Fig. 7G) three-segmented; first segment about 1.4 times as long as wide, 3 spiniform setae on its distal border; second segment about 2.5 times as long as wide, also bearing 3 strong spiniform setae on the distal border; third segment with blunt apex and a single seta. Antennae (Fig. 7F) with 5 segmented peduncle, relative size of antennomeres 5>4>3>2>1; antennal flagellum with 11–13 articles. Dactylus of pereopods with outer claw longer than inner one; no sexual dimorphism observed in pereopods 1 (Fig. 7H) and 7 (Fig. 7I). Male pleopod 1 endopodite (Fig. 7A) with obtuse triangular projection, bearing 2–3 strong, blunt setae, up to 1.5 times as long as endopodite; caudal and inner margins with pilose setae. Pleopod 1 exopodite (Fig. 7B) with broadly rounded caudal margin bearing 3–4 strong, blunt setae, 0.7–0.9 times as long as exopodite. Male pleopod 2 exopodite (Fig. 7C) 2 times as wide as long; inner and most part of frontal margin with dense, hairy setation, as in outer caudal corner; caudal margin with 5–6 short but strong setae. Male pleopod 2 endopodite (Fig. 7D–E) distally broadened, with rounded tip presenting a row of small denticles in the inner corner and a short, squarish terminal projection in the distal margin; inner margin with minute spiniform setae, larger and more conspicuous at base. Telson (Fig. 6) with caudal margin obtusely produced. Uropod (Fig. 7J) with endopodite 1.3–1.4 times as long as exopodite when not broken, and about 2 times as long as basipodite.
Distribution
The species has been found scattered in the southern Blue Ridge Mountains (Fig. 6), at low to midaltitudes. All studied specimens have been collected in leaf litter from hardwood forests.
Remarks
Ligidium protuberans sp. nov. corresponds with Ligidium sp. 3 in Recuero & Caterino (2024a). This species is closely related to L. enotahensis sp. nov. and L. schultzi sp. nov. (Fig. 1A), but it can be easily diagnosed from them by the conspicuous short projection present in the male pleopod 2 endopodite. All three gene fragments analyzed are informative to identify this species, with high interspecific p-distances for Cox1, and low to medium in the conserved NaK and 28S fragments (Supp. file 1), forming a reciprocally monophyletic clade in all cases.
description: Published as part of Recuero, Ernesto & Caterino, Michael S., 2025, Is there anybody (new) out there? Seven new species of Ligidium (Isopoda, Oniscidea, Ligiidae) from the Southern Appalachians, eastern North America, pp. 133-170 in European Journal of Taxonomy 976 on pages 143-146, DOI: 10.5852/ejt.2025.976.2783, http://zenodo.org/record/14844794