Lepechinelloides polymetallica Peart & Lörz, 2026, sp. nov.

Lepechinelloides polymetallica sp. nov. Figs 1, 2, 3, 4 Type material. Holotype: Pacific • 3 mm; Clarion-Clipperton Zone; 12.045 ° N, 117.424 ° W, 4223 m; 16 March 2015; Ocean Mineral Singapore exploration contract area, RV Thompson, ABYSSLINE-2 Cruise, Station AB 2 - EB 12; SMF 63356; COI (PQ 734637). Type locality. Clarion-Clipperton Zone, 12.045 ° N, 117.424 ° W, 4223 m. Etymology. The species name polymetallica refers to the habitat where the new species was sampled, a polymetallic nodule field in the East Pacific; it is used as a noun in apposition. Diagnosis. Body not strongly setose, each pereonite with small upright projection dorsally. Head with two projections mediodorsally. Antenna 1 peduncle similar in length to the length of antenna 2 peduncle articles 4 and 5 combined. Accessory flagellum of one article, about one-third the length of the first article of flagellum, without aestethascs. Mandible right lacinia mobilis seven-dentate, left lacinia mobilis eight-dentate. Maxilla 2 apical margin of outer plate obliquely sloping medially. Maxilliped setation of palp articles 1–3 straight, not curved; palp article 4 unguiculate, unguis same length of basal part. Pereopod 3 without extra projections, without a spine apically. Pleonite 3 with small, dorsal, vertical directed projection. Description. Based on holotype, male, 3 mm, SMF 63356. Body (Figs 1, 4) with sparse tuft-like projections (these are cuticular projections that have an apically or subapically inserted slender seta giving a “ tufted ” look) mainly along dorsal mid-line and a smaller in size lesser row mid-laterally, not strongly setose (see Fig. 1 CLSM). Pereon (Figs 1, 4) all segments weakly laterally dentate with small dorsal tuft-like projections, pereonites 1–7 with main dorsal projection at the distal margin middorsally, all of similar size. Pleon (Figs 1, 4) each segment with one dominant and one smaller projection along the midline. Projections directed vertically and are relatively short. Epimera (Figs 1, 4) each with large acute tooth on the ventral margin, each directed ventrally; posterior margin reduced and angled. Ventral teeth smallest on epimeron 1, epimeron 2 and 3 of similar size. Urosome (Figs 1, 4) urosomite 1 weakly produced to form a small rounded distal dorsal tooth, and with rounded proximal hump; urosomites 2 and 3 fused, without projections. Head (Figs 1, 4): two tufted dorsal projections; lacking rostrum and cephalic lobes. Antenna 1 (Figs 1, 2) longer than body; first article of peduncle 0.7 × length of second article, with sparse slender simple setae on margins; second article 2.0 × length of third article, with one robust seta on each margin and sparse long slender plumose setae, third article 0.7 × length of first article, with sparse long, slender, plumose setae; flagellum 1.6 × peduncle, 14 - articulate; accessory flagellum short, one articulate, reaching 0.3 × first article of flagellum. Antenna 2 (Figs 1, 2) longer than antenna 1, peduncular article 4, 80 % length of article 5; flagellum longer than peduncle, flagellum with 10 articles. Mouthparts (Fig. 2): upper lip symmetrically rounded, almost quadrate, setose at apical end. Mandible (Fig. 2) incisors dentate, left with five teeth, right with nine teeth; left lacina mobilis with eight teeth and eight toothed accessory robust setae, right lacinia mobilis with seven teeth and three accessory robust setae; molar very weakly triturative; palp one-articulate, short and tipped with one slender plumose seta apically. Lower lip (Fig. 2) inner lobes missing from dissected part, this is uncertain whether they are genuinely lacking or missing during dissection as the animal was very small, outer lobes setose at apical margins. Maxilla 1 (Fig. 2) inner plate small, reaching about two-thirds the length of the outer plate, tipped with two slender, plumose setae; outer plate with seven dentate spine teeth distally; palp two-articulate with three long plumose setae apically. Maxilla 2 (Fig. 2) inner plate shorter and slightly more slender than outer plate, tipped with five long slender, plumose setae, outer plate angled medially and lined with eight long slender plumose setae. Maxilliped (Fig. 2 – twisted in illustration) inner plate small, with three robust and three slender setae apically; outer plate ovoid, lined with six robust setae medially; palp second article longest, as long as third and fourth articles combined, unguis of dactyl as long as basal part. Pereon: gnathopod 1 (Fig. 3) subchelate; shorter than gnathopod 1, coxa triangular and longer than pereonite 1, longer than wide, extended ventrally, tapering, acute distally, slightly curved anteriorly, lined with both peg-like projections / setae and long slender, plumose setae, a small additional posterior projection; ratio of article length from basis to dactylus 1.0: 0.1: 0.2: 0.8: 0.5: 0.4; articles ranging from basis to propodus are lined with long slender plumose setae. Basis slender, elongate, margins subparallel, length equal to carpus and merus lengths combined; carpus long, widened distally, setose on both margins; propodus swollen and ovoid, strongly setose, more rounded than proximal articles and produced posteriorly to form a slight rounded heel, palm highly angled not defined but lined with robust setae, palmar margin marked by three robust spines. Gnathopod 2 (Fig. 3) subchelate, longer than gnathopod 1, coxa triangular and longer than pereonite 2, longer than wide, extended ventrally, tapering, acute distally, not curved anteriorly, lined with both peg-like projections / setae and long slender, plumose setae, and robust setae, a reduced additional posterior projection; ratio of article length from basis to dactylus 1.0: 0.1: 0.4: 0.8: 1.0: 1.0; articles ranging from basis to propodus with sparse long slender plumose setae, propodus more rounded than proximal articles and produced posteriorly to form a slight heel, palm highly angled not defined but with only sparse robust and plumose setae. Pereopod 3 (Figs 1, 3) margins of all articles sparsely lined with long slender plumose setae; coxa small and triangular, tipped with two long plumose slender setae at apex, ratio of length of coxa to dactylus 1.0: 4.6: 0.6: 1.5: 4.4: 2.2: 1.5; dactylus tipped with a bifid unguis that is 0.2 × length of whole dactylus. Pereopod 4 (Figs 1, 3) margins sparsely lined with long slender plumose setae; coxa small and lobate, giving the impression of being triangular, tipped with three long plumose slender setae at apex, ratio of length of coxa to dactylus 1.0: 3.8: 0.6: 1.0: 3.1: 2.4: 2.8, dactylus tipped with a bifid unguis that is 0.1 × length of whole dactylus. Pereopod 5 (Figs 1, 3) margins sparsely lined with long slender plumose setae and occasional peg-like setae; coxa small and triangular, tipped with four long plumose slender setae at apex, ratio of length of coxa to carpus 1.0: 3.4: 0.5: 0.9: 2.7, propodus and dactylus broken off. Pereopod 6 (Figs 1, 3) damaged, broken between ischium and merus, margins sparsely lined with long slender plumose setae and sparse peg-like setae; coxa small and triangular, tipped with one long plumose slender seta at apex, ratio of length of coxa to dactylus 1.0: 4.2: broken: broken: 5.1: 3.1: 2.5, dactylus tipped with bifid unguis 0.1 × of whole dactylus. Pereopod 7 (Figs 1, 3) coxa small and rounded, tipped with one long slender plumose seta, distal articles broken off at carpus. Urosome (Figs 1, 4): uropods slender and elongated, biramous, rami styloid. Uropod 1 (Figs 1, 4) longest of the three uropods, twice the length of uropod 3, peduncle 0.4 × as long as the shorter outer ramus, strong peg-like robust setae lining the peduncle and rami, outer ramus slightly shorter than inner ramus. Uropod 2 (Figs 1, 4) peduncle 0.3 × length of shorter outer ramus; outer ramus slightly shorter, 0.8 × inner ramus; both rami with spines on margins and apical tips. Uropod 3 (Figs 1, 4) peduncle very short, 0.3 × shorter than inner ramus, outer ramus slightly shorter than inner, with robust setae; rami slightly damaged at tip. Telson (Fig. 4) slightly longer than broad; cleft 60 % of length, widely cleft u-shaped; apices each bearing three long slender plumose setae. Remarks. Lepechinelloides polymetallica sp. nov. fits in the genus due to the diagnostic characters of the genus. These include large processes located on the dorsal midline, head lacking eyes, rostrum and cephalic teeth, urosome segments 2 and 3 fused, mandibular palp one-articulate and the uropod rami immensely long. It differs from the genus diagnosis by the proportion of antenna 1 peduncle article 2 to article 3, which is subequal in the original diagnosis and distinctly twice as long in this new species. It has been decided by the authors to place this new species in the genus Lepechinelloides despite the differences in the diagnosis. This decision is mainly due to the fact this is a single specimen of only 3 mm in length. Until more material is available this species should be placed in Lepechinelloides. Lepechinelloides polymetallica differs from both L. karii and L. weddellensis by the possession of small upright pointing extensions and reduced setation on all pereonites (versus strong setae and spines and no extensions on the pereonites of L karii and L. weddellensis), and the reduced dorsal, vertical projection on pleonite 3 (large and posteriorly directed in both L. karii and L. weddellensis), ventrally directed midventral extensions on pleonites 1–3 (ventrally directed in L. weddellensis but angled in L. karii), the widened propodi of both gnathopods (narrow and not expanded in both L. karii and L. weddellensis), the lack of spines on coxa 5–7 and the large perpendicularly extended gland cone on antenna 2. Despite being both molecularly and morphologically characterised there would be a great benefit having comprehensive molecular information on the other species in this genus. Due to the enigmatic nature of these