Meridiosignum minidenticulatum Just & Wilson, 2007, sp. nov.
Creators: name: Just, Jean
name: Wilson, George D. F.
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Paramunnidae
Meridiosignum
Meridiosignum minidenticulatum

description: Meridiosignum minidenticulatum sp. nov.
Figs 7–8
Type fixation. Holotype, Ψ, AM P60890. Here designated.
Type locality. Macquarie Island, Australia.
Etymology. The species is named for the numerous small denticles on the lateral margins of the pleotelson.
Material examined. Holotype. preparatory Ψ, 1.40 mm, Aerial Cove, Macquarie Island, 54° 29' S, 158° 57' E, 2 February 1978, fine sediments in cracks and crevices and under rock overhangs, 3-4.5 m, coarse sediments from small sediment patches on level bottom, stn MA-382, AM P60890.
Paratypes. 12 ɗ, 21 Ψ, same data as holotype, AM P75374.
O ther material (this material is in poor condition having dried out or been roughed up during sampling, and is therefore not suitable as paratypes). 1 terminal ɗ, Australia, Macquarie Island (54° 30' S, 158° 57' E), 26 Jan 1978, stn MA-357, AM P60888. 2 ɗ, 6 Ψ, Caroline Cove, Macquarie Island, Australia, off large rock on south west side of Cove, 54° 46’S 158° 48’E, 8 m, Plocamium, Codium, Ophiocantha and a scallop collected by R.W. Ricker, all from boulders in dense Macrocystis pyrifera bed, J.K. Lowry (SCUBA), 15 January 1978, stn MA-300, NMV J52111. 3 ɗ, 2 Ψ, Caroline Cove, Macquarie Island, Australia, three rocks at mouth of cove, 54° 46’S 158° 48’E, red algae from dense Macrocystis bed, 13-18 m, J.K. Lowry (SCUBA), 16 January 1978, stn MA-307, NMV J52112. 78 specimens, Caroline Cove, Macquarie Island, Australia, inner cove north of hut, 54° 46’S 158° 48’E, Codium flat adjacent to Macrocystis bed, 13 m, J.K. Lowry (SCUBA), 17 January 1978, stn MA-311, NMV J52114. 1 ɗ, 2 Ψ, Aerial Cove, Macquarie Island, Australia, 54° 29’S 158° 57’E, 5 m, mainly bryozoans from sheltered base of vertical face near Cove entrance; dominant alga, Codium, J.K. Lowry (SCUBA), 12 December 1977, stn MA-107, NMV J52118. 2 Ψ, 1 juvenile ɗ, Caroline Cove, Macquarie Island, Australia, off large rock on south west side of Cove, 54° 46’S 158° 48’E, 8 m, Macrocystis pyrifera holdfasts, dictyotalean, Plocamium and a red tunicate from dense Macrocystis bed on boulder bottom, J.K. Lowry (SCUBA), 15 January 1978, stn MA-298, NMV J52119.
Description. Body ovate (female) or tapering posteriorly (terminal male); width 0.68 length in female, width 0.58 length in male, widest in female at pereonite 3, widest in male at pereonites 1–3. Head length 0.49–0.51 width (male, female respectively); length posterior to eyestalks 1.2 anterior length, 1.6 anterior length in terminal male. Frontal margin with angular lateral margins adjacent to antennae, shallow convex, almost straight medially. Eyestalks in female length 2.6 width, male length 3.7 width, apex rounded, shaft before apex constricted proximally, long axis angling forward at approximately 40° in female, 35° in terminal male.
Pereonites 1–4 lateral margins not projecting, coxae not visible in dorsal view. Pereonite 1 of terminal male greatly enlarged. Pereonite 1 sagittal length in female 3.0 pereonites midline length, 3.1 in male. Pereonite lateral margin 1 rounded, 2–4 linear, 5–7 rounded. Pereonite lateral margins 6 smooth, 7 with denticles on posterolateral margin forming only.
Pleon length 1.10 width in female, 1.20 in male. Pleonite 1 width 0.81–0.84 distance between uropods (terminal male, female respectively), length 0.3 width. Pleotelson laterally rounded, lacking inflection between lateral and proximal margins; lateral margin convex, denticulate, with 16–17 denticles per side. Pleotelson posterior margin forming 80° angle, set apart from lateral margins by concavity at level of uropods.
Antennula articles 1–2 combined extending beyond eyestalk apex, 1 shorter and broader than 2, inflated; 4–6 of subequal length, shorter than 3.
Antenna article 3 in ventral view tubular, width 0.33–0.57 length (female, terminal male respectively), 5 distinctly longer than article 4; flagellum with 7 articles, proximal article distinctly longer than more distal articles, 1.8 length of second article.
Pereopod I coxa with short, convex anterior projection in terminal male; basis with crenate ridge on anterior margin, basis length 3.4 width; ischium anterodistal margin with sharp spines in row (male); merus with 1 spine on anterior margin (male); carpus triangular, distal width 1–1.3 posterior margin length (female, male respectively), posterior margin with 2 denticles proximal to robust setae (some specimens lack one denticle), 1 denticle between robust setae, one denticle distal to robust setae; propodus narrowing distally to insertion of dactylus, with 2 robust setae, with crenate ridge on opposing margin. Pereopod II basis with crenate ridge. Pereopod V-VII coxae with 1 or 2 denticles in female, smooth in male.
Male pleopods I lateral lobes distinctly projecting from midlateral margin, width 0.4 distance to midline; distal projection length 0.30 pleopod total length, forming acute angle, with pointed apices. Female operculum distal part tapering with concave distolateral margins, width 0.75 length.
Uropods dorsal and directly adjacent to lateral margin of pleotelson.
Size. Largest Ψ, 1.40 mm; largest ɗ, 1.40 mm.
Distribution. Macquarie Island, Australia. 3–4.5 m.
Remarks. Meridiosignum minidenticulatum sp. nov. differs from congeners by the larger number and smaller denticles on the lateral margin of the pleotelson. It differs from M. kerguelensis in having the lateral margins of pereonites 2–4 linear (concave in M. kerguelensis). In Meridiosignum subtilis the eyestalks angle forward at approximately 55° (35–40° in M. minidenticulatum). Meridiosignum menziesi is the only species with 1 in stead of 2 robust setae on posterior margin of pereopod I propodus.
description: Published as part of Just, Jean & Wilson, George D. F., 2007, Revision of Austrosignum Hodgson and Munnogonium George & Strömberg (Paramunnidae) with descriptions of eight new genera and two new species, (Crustacea: Isopoda: Asellota), pp. 1-29 in Zootaxa 1515 on pages 19-21, DOI: 10.5281/zenodo.177291