Unispinosus eopacificus Chim & Tong 2020, n. sp.
Creators: name: Chim, C. K.
name: Tong, Samantha J. W.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Typhlotanaidae
Unispinosus
Unispinosus eopacificus

description: Unispinosus eopacificus n. sp.
(Figs 1–5, Table 2)
Material examined. Holotype, non-ovigerous female, dissected and mounted on 25 slides (ZRC 2020.0155), 3.6 mm, Clarion-Clipperton Fracture Zone (CCFZ), OMS exploratory area, station S12 (12°01.641’N, 117°19.512’W), 4127 m, box corer (deployment # BC26), layer 0–2 cm, sieve mesh size 300 µm, ABYSSLINE II (AB02) cruise, 17 March 2015; allotype, adult male, dissected and mounted on eight slides (ZRC 2020.0156), 3.1 mm, station S08 (12°11.404’N, 117°22.281’W), 4172 m, box corer (deployment # BC24), layer 2–5 cm, sieve mesh size 300 µm, 14 March 2015; paratypes, two non-ovigerous females (ZRC 2020.0157, ZRC 2020.0158), same collection data as holotype; paratype, one non-ovigerous female (ZRC 2020.0159), layer 2–5 cm, other collection data as holotype; paratype, one manca (ZRC 2020.0160), sieve mesh size 250 µm, other collection data as holotype; one non-ovigerous female (ZRC 2020.0161), station S11 (12°00.559’N, 117°22.819’W), 4148 m, box corer (deployment # BC25), layer 2–5 cm, sieve mesh size 300 µm, 15 March 2015.
Diagnosis. As with characters of genus.
Description. Non-ovigerous female holotype ZRC 2020.0155.
Body (Fig. 1A; Fig. 5A for CLSM image of female paratype ZRC 2020.0159) elongate, subcylindrical and about eleven times as long as wide. Cephalothorax suboval in dorsal view, naked and about 13% of body length.
Pereon about 63% of body length; pereonites 1 and 6 shortest, as long as wide; pereonites 2 to 5 of subequal length, each 1.3 times as long as wide; pereonites 2 to 6 each bearing a simple seta at each anterior corner.
Pleon about 24% of body length; all five pleonites of subequal length, each 0.3 times as long as wide, rounded and with one simple seta laterally; pleotelson (Figs 1A, 4H) about 10% of body length, covered by dorsal plate, with one simple seta near uropod basal article, posterior margin rounded bearing two minute spiniform, two short simple and four long simple setae.
Antennule (Fig. 2A) with four articles, about 0.7 times as long as cephalothorax; article-1 longest, about 0.5 times as long as total length of antennule, with one minute seta medially and five simple setae distally; article-2 about 0.6 times as long as article-1, with one minute and two long simple setae distally; article-3 shortest, about 0.3 times as long as article-2, with one minute and one long simple setae distally; article-4 about 2.5 times as long as article-3, with one complex aesthetasc and seven simple setae.
Antenna (Fig. 2B) with six articles, about 0.6 times as long as antennule; article-1 damaged during dissection and not examined; article-2 with three simple setae and dorsodistal process bearing one large spiniform seta; article- 3 about 0.8 times as long as article-2, naked; article-4 longest, about 0.5 times as long as total length of antenna, without visible fusion line, with one long simple seta at mid-length and four simple setae distally; article-5 about 0.5 times as long as article-4, with one simple seta distally; article-6 shortest, about 0.3 times as long as article-5, with four simple setae.
Labrum (Fig. 2C) hood-shaped, densely covered by setules and with one long simple seta on each lateral side. Left mandible (Fig. 2D) molar with blunt or turberculiform projections and two spiniform setae distally; incisor sharp; lacinia mobilis wide with smooth edge. Right mandible (Fig. 2 D’) molar damaged during dissection. Labium (Fig. 2E) with two pairs of lobes, each with many setules distally; outer lobe membranous bearing one spiniform seta distally. Epignath not examined. Maxillule (Fig. 2F) endite with nine spiniform setae, one simple seta and some setules distally and numerous simple setae proximally; palp with two long terminal setae. Maxilla lost during dissection. Maxilliped (Fig. 2G) bases not fused distally, each with one simple seta distally; endite without tubercles and with two simple setae distally; palp article-1 naked; article-2 with one short simple, one long simple and one long spiniform setae on inner margin; article-3 with one short simple and two long setulose spiniform setae on inner margin and a row of microtrichia distally; article-4 with five long setulose spiniform setae distally.
Cheliped (Fig. 3A) basis with long posterior lobe, naked; merus with one simple seta ventrally; carpus wide proximally and narrow distally, with one minute seta dorsally and two simple setae ventrally; propodus as long as carpus. Chela palm narrow proximally and wide distally, with one simple seta on outer margin distally, one setulose seta on inner margin distally, one strongly-chitinised rounded process at ventral margin (Fig. 5B for CLSM image of female paratype ZRC 2020.0159) bearing one single-sided setulose spiniform seta distally and another similar process at dactylus insertion; fixed finger with two simple and one spiniform setae on outer margin dorso-proximally; dactylus with strong unguis.
Pereopod-1 (Fig. 4A) coxa with one simple seta; basis narrowest proximally and widest distally, about 3.0 times as long as wide; ischium short, less than 0.1 times as long as basis, with one minute seta ventrally; merus about 0.4 times as long as basis, with two simple setae ventrodistally; carpus slightly longer than merus, with one simple and three setulose spiniform setae distally; propodus about 0.7 times as long as basis, with one simple seta and numerous setules dorsodistally, numerous setules along ventral margin and one setulose spiniform seta ventrodistally; dactylus with some setules on proximal process dorsodistally; dactylus and unguis subequal in length, slender and almost straight, combined length about 0.8 times as long as propodus.
Pereopods 2 and 3 (Figs 4B, 4C) similar to pereopod-1 but with numerous setules proximally.
Pereopod-4 (Fig. 4D) coxa with microtrichia and one simple seta; basis narrowest proximally but otherwise similar in width along entire length, about 3.7 times as long as wide, with some microtrichia, setules and simple setae proximally; ischium short, less than 0.1 times as long as basis, with two simple setae ventrodistally; merus about 0.4 times as long as basis, with two setulose spiniform setae ventrodistally; carpus slightly longer than merus, with one simple and three setulose spiniform setae distally; propodus about 0.5 times as long as basis, with one plumose seta dorsomedially, one setulose seta dorsodistally and two setulose spiniform setae ventrodistally; dactylus and unguis slender and almost straight, combined length about 1.6 times as long as propodus; unguis about 0.7 times as long as dactylus.
Pereopod-5 (Fig. 4E) similar to pereopod-4 but dactylus with some short setules ventrally.
Pereopod-6 (Fig. 4F) similar to pereopod-5, except that ischium with only one seta; propodus without dorsomedial plumose seta and with three dorsodistal setae.
Pleopods rudimentary.
Uropod (Fig. 4H) basal article about 2.0 times as long as wide, naked; endopod biarticulate; article-1 with one simple seta distally; article-2 about 0.4 times as long as article-1, with six simple setae distally; exopod uniarticulate, as long as endopod article-1, with one simple seta subdistally and two simple setae distally.
Male allotype ZRC 2020.0156 (Figs 1B, C): Similar to female holotype but with pleopods.Antennule with some plumose setae (Fig. 2A). Chela fixed finger with one simple, one setulose and one spiniform setae dorso-proximally. Pleopods 1–5 (Fig. 4G) similar; biramous; basal article naked; endopod and exopod almost identical, slender and brush-like, with nine simple setae distally (of which one of these setae is placed subdistally on endopod).
Female paratype ZRC 2020.0159 (Fig. 5): Similar to female holotype.
Etymology. The specific epithet refers to the eastern Pacific Ocean where the species was found.
Type locality. Station S12 of OMS exploratory area at the Clarion Clipperton Fracture Zone, 4127 m.
Distribution and habitat. Three stations (S08, S11 and S12) of OMS exploratory area at CCFZ, 4127–4172 m; 0–5 cm layer of soft sediment with shear strength of 0.625 –2.813 kPa and surface nodule coverage of 0.0–38.5%.
opods 4–6 dactylus and unguis combined length: short = as long as or shorter than propodus; long = longer than propodus
description: Published as part of Chim, C. K. & Tong, Samantha J. W., 2020, Two new species of paratanaoid tanaidaceans of the family incertae sedis (Crustacea: Peracarida) from polymetallic nodule fields in the eastern Clarion-Clipperton Fracture Zone, pp. 461-485 in Zootaxa 4758 (3) on pages 465-471, DOI: 10.11646/zootaxa.4758.3.3, http://zenodo.org/record/3734675