Ligidium gadalutsi, Recuero & Caterino, 2025

Ligidium gadalutsi sp. nov.

urn:lsid:zoobank.org:act:3EAEAB27-5C45-4183-9B5D-70FB794D8094

Figs 8–9 View Fig View Fig

Ligidium sp. 4 – Recuero & Caterino 2024: table 1.

Diagnosis

This new species differs from all other Appalachian species in its male pleopod 2 endopodite having an acuminate tip, strongly projected posteriorly and outwards. It has a distinctive male pleopod 1 endopodite, showing a poorly defined, broadly triangular projection, and a male pleopod 1 exopodite with its caudal margin flattened. It also differs from all other Appalachian species based on molecular data, representing a distinct evolutionary lineage with no close relationships among the studied taxa.

Etymology

A noun in apposition, ‘ gadalutsi ’ is the Cherokee word that originated the name Cataloochee, and consequently the origin of the name of the type locality, Big Cataloochee Mountain.

Material examined

Holotype

USA – North Carolina • ♂; Haywood Co., Great Smoky Mountains N.P., Big Cataloochee Mt ; 35.6675° N, 83.1805° W; 1703 m a.s.l.; 14 Jul. 2020; M. Caterino and F. Etzler leg.; GenBank no: PP737148 (Cox1); USNM, CUAC000138053 About CUAC .

GoogleMaps

Other material examined

USA – North Carolina • 1 ♀; Clay Co., Nantahala N.F., Chunky Gal Trail ; 35.1471° N, 83.7144° W; 1274 m a.s.l.; 6 Jul. 2021; M. Caterino and E. Recuero leg.; CUAC000171281 About CUAC GoogleMaps . – Tennessee • 1 ♀; Sevier Co., Smoky Mountains N.P., Mount LeConte (Alum Cave Trail) ; 35.6382° N, 83.4387° W; 1317 m a.s.l.; 28 Sep. 2021; M. Caterino and E. Recuero leg.; CUAC000171324 About CUAC GoogleMaps .

Description

Body length of holotype 4.9 mm, width (at 4 pereonite) 2.4 mm; body length of females 5.5–7 mm, width 2.5–3.6 mm. Color in ethanol ( Fig. 8 View Fig ) of holotype dorsally marbled brown and white, with a conspicuous dark brown longitudinal medial stripe running from pereonite 1 to pereonite 7 and a transversal dark brown band in the caudal margin of pereonites; epimera dark brown with a large white patch at the base; pleonites dark brown with lateral white spots; telson dark brown with a white anchor-shaped spot; head and antennae marbled brown and white, distal segments of antennae darker brown with white setae bundle in flagellum; uropod brown with a white spot in the inner part of basipodite; pereopods and pleopods white with brown marbling. Among females one resembles the holotype in coloration, the other is dorsally almost black with large white spots from head to telson. Antennule ( Fig. 9G View Fig ) three-segmented; first segment about 1.5–1.7 times as long as wide, 2–3 spiniform setae in its distal border; second segment about 2.3–2.5 times as long as wide, bearing 3 strong spiniform setae in the distal border; third segment with blunt apex and 2 setae. Antennae ( Fig. 9F View Fig ) 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, inner one reduced in pereopod 1; no sexual dimorphism observed in pereopods 1 ( Fig. 9H View Fig ) and 7 ( Fig. 9I View Fig ). Male pleopod 1 endopodite ( Fig. 9A View Fig ) with short, blunt projection, bearing a single strong, blunt seta, 0.8 times as long as endopodite; caudal and inner margins with pilose setae. Pleopod 1 exopodite ( Fig. 9B View Fig ) with flat caudal margin bearing 4 strong, blunt setae, up to 0.8 times as long as exopodite. Male pleopod 2 exopodite ( Fig. 9C View Fig ) 1.9 times as wide as long; inner and half of the frontal margin with dense, hairy setation, as in outer caudal corner; caudal margin evenly convex, with 2 short, strong setae in the outer corner. Male pleopod 2 endopodite ( Fig. 9D–E View Fig ) with a broad and acuminate tip, projected posteriorly-laterally, with small setae in the interior margin; inner margin of the peduncle with minute spiniform setae, no spines at base. Telson ( Fig. 8 View Fig ) with caudal margin slightly concave in the sides and obtusely produced in the middle. Uropod ( Fig. 9J View Fig ) 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 in two localities in the Great Smoky Mountains and one at the Nantahala National Forest further south, at mid- to high elevations ( Fig. 8 View Fig ). Studied specimens have been collected in leaf litter from conifer and mixed forests.

Remarks

Ligidium gadalutsi sp. nov. corresponds with Ligidium sp. 4 in Recuero & Caterino (2024a). It is not closely related to any of the studied Appalachian species ( Fig. 1A View Fig ). The shape of the male pleopod 2 endopodite somewhat resembles that of L. mucronatum , which could indicate a shared ancestry. However, in L. mucronatum the tip is shorter and blunt, while much longer and acuminate in L. gadalutsi . This new species shows the highest genetic p-distances compared to all other studied species (Supp. file 1).