Munnogonium longicaudatum, Just & Wilson, 2021

Just, Jean & Wilson, George D. F., 2021, Redescriptions and new species in the ‘ Austrosignum-Munnogonium’ complex sensu Just & Wilson (2007), mainly from the Southern Hemisphere (Crustacea Isopoda: Paramunnidae), Zootaxa 4952 (3), pp. 401-447 : 431-436

publication ID	https://doi.org/ 10.11646/zootaxa.4952.3.1
publication LSID	lsid:zoobank.org:pub:837C9916-5232-4D49-9D0D-050B539CD965
DOI	https://doi.org/10.5281/zenodo.4690296
persistent identifier	https://treatment.plazi.org/id/03C487E3-7837-640B-FF09-E88CE91DFB07
treatment provided by	Plazi
scientific name	Munnogonium longicaudatum
status	sp. nov.

Treatment

Munnogonium longicaudatum View in CoL sp. nov.

( Figs 19–21 View FIGURE 19 View FIGURE 20 View FIGURE 21 )

Type fixation. Holotype, ♂, NMV J18983 View Materials .—Here designated.

Type locality. Australia, New South Wales .

Etymology. The epithet is a reference to the elongate pleon of this species.

Material examined. Holotype, ♂, 1.8 mm, Australia, New South Wales, off Nowra , 34 o 59.52’S, 51 o 5.94’E, 204 m, coarse shell, WHOI epibenthic sled, GCB Poore et al., RV Franklin, 14 July 1986, stn SLOPE 1, NMV J18983 View Materials . Unique. GoogleMaps

Description (male). Body width 0.40 length, widest at pereionite 5, with scattered dorsal setae; pereionites 1–4 with weak transverse ridge dorsally. Head length 0.54 width; length posterior to eyestalks subequal to anterior length. Frontal margin broadly rounded without angular lateral margins adjacent to antennae. Eyestalks vestigial, length equal to width, apex rounded, long axis angling forward at 25° degrees.

Pereionite 1 sagittal length 1.8 pereionites midline length; lateral margin of pereionites 1–7 rounded. Coxal plates 1–7 rounded, visible in dorsal view.

Pleon length 2.0 width. Pleonite 1 width 0.7 distance between uropods, length 1.3 width. Pleotelson lateral margin convex, smooth, without inflection between lateral and proximal margins; anterior length in ventral view 0.1 total pleotelson length; posterior projection forming 80° angle, evenly curving into lateral margins, apex bluntly pointed.

Antennula article 1 about 3 times longer than rounded eyestalk; articles 1 and 2 of equal length, article 1 reaching well beyond pereionite 1 lateral margin, article 1 tubular, width subequal to 2; article 2 apical margin with tuft penicillate setae; article 3 as long as subequal sized articles 4–6 combined. Antenna article 3 tubular, width 0.25 length, article 5 distinctly longer and slenderer than article 4; flagellum with 5 articles, articles 1 and 2 subequal, 3–5 successively shorter.

Pereiopod I basis anterior margin smooth, length 4.3 width; ischium smooth; merus posterior margin with one robust seta on distal corner; carpus oval, posterior margin with 3 subequal robust setae, with crenate ridges proximal to posterior 2 robust setae and at base of middle robust seta; propodus narrowing distally to insertion of dactylus, with 1 robust seta among simple setae, opposing margin fimbriate. Pereiopod II carpus and propodus ventral margin with rows of about 8–9 long, stiff curved robust setae; unguis much longer than slender dactylus, ventral claw as long as dactylus; pereiopod VII articles with few simple setae and some short, slender robust setae.

Male pleopods I lateral lobes moderately projecting from lateral margin, width 0.3 distance to midline; distal projection length 0.32 pleopod total length, forming acute angle of 70 o, with rounded apices.

Uropods dorsal and directly adjacent to lateral margin of pleotelson in dorsal view; protopod absent or hidden.

Size. Male, 1.8 mm.

Distribution. Off Nowra, New South Wales, Australia, 204 m.

Remarks. Munnogonium longicaudatum sp. nov. is characterised primarily by the much elongate pleonite 1 in males (females unknown). It shares this character with Munnogonium waldronense George & Strömberg, 1968 (type species of genus) and M. quequensis Doti & Roccatagliata, 2013 , but the former has a straight to concave head frontal margin as opposed to a broadly convex head in the new species; M. quequensis has a mid-frontal round projection with micro-setae on the head.