Liberonautes njala Ndongo, Rintelen, Clark & Cumberlidge, 2024, sp. nov.
Creators: name: Mvogo Ndongo, Pierre A.
name: von Rintelen, Thomas
name: Clark, Paul F.
name: Cumberlidge, Neil
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Potamonautidae
Liberonautes
Liberonautes njala

description: Liberonautes njala sp. nov.
(figs. 2B, 3B, 4B, 5B, 6 F-J, 7D-F)
Material examined.— Sierra Leone. Holotype: adult ♂ (CW 66.3, CL 44.2, CH 30.0, FW 20.1 mm), Tai River, near Njala Campus (08°06ļ14.9ļļN 12°05ļ00.9ļļW), Southern Province, 65 m asl, coll. P. A. Mvogo Ndongo, 19 January 2021 (ZMB Crust. 33102). Paratype: adult ♂ (CW 52.3, CL 35.6, CH 23.1, FW 16.5 mm) (ZMB Crust. 33103), all same data as holotype. Non-types: 3 subadult ♂♂ (CW 28.4, 32.3, 37.1, CL 21.2, 23.5, 26.9, CH 13.3, 14.0, 15.9, FW 9.6, 10.5, 12.6 mm, respectively) bridge at Taiama (08°12ļ13ļļN 12°3ļ58.3ļļW), River Tai, Southern Province, 61 m asl, coll. P.A. Mvogo Ndongo, 19 January 2021 (CARC-03).
Diagnosis.— Large species, adult between CW 52-66 mm; postfrontal crest incomplete, not traversing carapace, ends not encountering carapace margins; anterolateral, posterolateral carapace surfaces smooth (figs. 2B, 3B, 5B); semicircular, urogastric, cardiac, cervical, transverse branchial carapace grooves all deep, distinct (figs. 2B, 3B); exorbital tooth low, blunt (figs. 3B, 5B); intermediate tooth medium-sized, epibranchial tooth granular (figs. 3B, 4B, 5B); surface texture of branchiostegite subhepatic region smooth; major cheliped dactylus highly curved leaving broad oval interspace when closed (fig. 6F); G1TA length long, ca. half as long as G1SA (G1TA/G1SA = 0.5), G1SA lateral margin distinctly curved inward (fig. 7D, E).
Description of holotype.— Carapace transversely oval, wide (CW/FW = 3.3), moderately high (CH/FW l.4), front gently indented medially, wide (FW/CW = 0.3). Entire carapace surface generally smooth. Cervical grooves deep, long, ending just before encountering postfrontal crest; semicircular, urogastric, cardiac, cervical, transverse branchial grooves all deep (figs. 2B, 3B, 5B). Postfrontal crest distinct, consisting of fused epigastric crest, incomplete, not traversing entire carapace, lateral ends not meeting carapace margins; mid-groove on postfrontal crest short, forked. Exorbital tooth small, blunt, intermediate tooth triangular, medium-sized, epibranchial tooth small, low, granular (figs. 2B, 3B, 4B, 5B). Carapace lateral margin posterior to epibranchial tooth raised, marked by row of small granules, continuous with carapace posterolateral margin. Carapace posterior margin rounded, width subequal to FW (figs. 2B, 3B). Carapace branchiostegite divided by transverse, vertical grooves into three regions (figs. 4B, 5B). Transverse suture beginning at respiratory opening, curving backward, dividing suborbital, subhepatic regions from pterygostomial region (figs. 4B, 5B); vertical sulcus curving backward to meet epibranchial tooth, dividing suborbital from subhepatic regions (figs. 4B, 5B). Suborbital, subhepatic, pterygostomial regions all smooth (figs. 4B, 5B).
Mandibular palp comprising basis plus two endopod articles; terminal article with small hardened ridge on superior margin near article junction (fig. 6I). Third maxillipeds filling entire buccal cavern except for transversely oval efferent respiratory openings visible at superior lateral corners; exopod with well-developed slender flagellum; ischium with distinct vertical sulcus (figs. 4B, 5B, 6J).
Thoracic sternal sulcus S2/3, deep, horizontal, ends not meeting side margins, S3/4 reduced to 2 short notches on margins, obscure in middle; episternal sulci S4/E4-S6/E6 visible, S7/E7 obscure (fig. 4B).
Chelipeds unequal (fig. 6F, G), right higher, longer than left (fig. 6F). Right chela movable finger (dactylus) highly arched, cutting edge lacking teeth, enclosing wide interspace; dactylus tip overlapping fixed finger (propodus pollex) tip when closed; fixed finger cutting edge with 4 small teeth proximally, otherwise lacking teeth (fig. 6F). Cheliped merus inferior margins smooth; distal meral tooth small, distinct; superior surface of merus with rows of carinae (fig. 6H). Cheliped carpus inner margin distal tooth large, pointed, proximal tooth small, pointed, followed by granules (fig. 6H). Walking legs P2-5 robust, P3 longest, P5 shortest; dactyli of P2-5 with short downward-pointing sharp bristles, P5 dactylus shortened (fig. 2B).
Pleomeres (PL1-6) and telson triangular with sinuous lateral margins (Fig. 4B). PL3 trapezoidal, broadest; PL4, PL5 trapezoidal. PL6 broader than long, rectangular (Fig. 4A). Telson triangular, with almost straight lateral margins Fig. 4B).
G1TA slim, curved, needle-like, long, ca. half as long as G1SA (G1TA/G1SA = 0.5); G1SA proximal half conspicuously broad, distal half abruptly narrow, columnar, lateral margin distinctly curved inward (fig. 7D, E); G2TA long, more than half length of G2SA (G2TA/G2SA = 0.6), flagellum-like (Fig. 7F).
Colour in life.— Dorsal carapace, pereiopods P1-5 dark violet (fig. 2B).
Etymology.— The new species is named for Njala, the type locality in the Southern Province, Sierra Leone. The species name njala is used as a noun in apposition.
Habitat.— Liberonautes njala sp. nov. is an aquatic species that was collected either in nets set in the river, or by hand, from under large rocks on the riverbed.
Distribution.— Known only from the River Tai, near the small town of Njala and Taiama, Southern Province, Sierra Leone (fig. 1).
description: Published as part of Mvogo Ndongo, Pierre A., von Rintelen, Thomas, Clark, Paul F. & Cumberlidge, Neil, 2024, Morphological and molecular evidence support four new Liberonautes Bott, 1955 (Decapoda, Potamonautidae, Liberonautinae) species of freshwater crabs from Sierra Leone, West Africa, pp. 709-731 in Crustaceana 97 on pages 718-721, DOI: 10.1163/15685403-bja10410, http://zenodo.org/record/15090630