Anisarthrus okunoi, Saito & Shimomura, 2015

Saito, Nobuhiro & Shimomura, Michitaka, 2015, A New Abdominally Parasitizing Bopyrid, Anisarthrus okunoi sp. nov. (Crustacea: Isopoda), Infesting the Hinge-Beak Shrimp Rhynchocinetes uritai Kubo, 1942 (Crustacea: Decapoda: Rhynchocinetidae), Species Diversity 20 (1), pp. 37-43 : 37-39

publication ID	https://doi.org/ 10.12782/sd.20.1.037
DOI	https://doi.org/10.5281/zenodo.4733922
persistent identifier	https://treatment.plazi.org/id/03EC87FB-3029-FFE9-FC0A-139B7075F8FF
treatment provided by	Felipe
scientific name	Anisarthrus okunoi
status	sp. nov.

Treatment

Anisarthrus okunoi View in CoL sp. nov.

[Japanese name: Sarasa-no-harayadori]

( Figs 1–3 View Fig View Fig View Fig )

Material examined. Holotype: ovigerous female (BL 3.88 mm), KMNH IvR 500,727, removed from ventral surface of pleon of hinge-beak shrimp Rhynchocinetes uritai (female, CL 6.98 mm), CMNH-ZC 02342 , Yura Harbor (34°17′30″N, 134°57′00″E), Sumoto city, Awaji Island, Hyogo Prefecture, central Japan, 6 m depth, 22 October 2008, coll. J. Okuno, K. Hanano, and T. Tamego. GoogleMaps Allotype: male (BL 1.12 mm), KMNH IvR 500,728, removed from pleon of holotype female. GoogleMaps

Description of holotype female (KMNH IvR 500,727). Body ( Fig. 1A, B View Fig ) markedly asymmetrical, greatly expanded on convex (left) side, approximating an inverted equilateral triangle in general outline; body axis distortion about 40º; maximal body width about 1.2 times as long as body length.

Head ( Fig. 1A View Fig ) quadrilateral, completely embedded in pereon, representing about 35% of body length; frontal margin concave and deeply cleft. Eyes absent. Right antenna 1 ( Fig. 2A View Fig ) of 3 articles, articles 2 and 3 with distal and terminal setae, respectively; right antenna 2 ( Fig. 2B View Fig ) of 5 articles, of which articles 2, 3, and 4 with marginal and distal setae, article 5 with terminal setae. Right and left maxillipeds ( Fig. 2C, D View Fig ) symmetrical, semi-ovoidal, nearly straight medially, roundly angled anteriorly, without palp, bearing short spur; anterior article about 2.4 times as long as posterior article. Barbula ( Fig. 2E View Fig ) with pair of short, stout lateral projections, its lateral margins expanded and mid-region produced slightly into medial point.

Pereon ( Fig. 1A View Fig ): pereomeres 1 and 2 completely distinct dorsally; pereomeres 3–7 distinct on concave (right) side and medially but segmental boundaries not clearly expressed on convex (left) side. All pereomeres with dorsolateral bosses on concave side. Inflated closed brood pouch ( Fig. 1B View Fig ) expanded far laterally, formed of fused convex oostegites 2–5. Oostegite 1 of convex side ( Fig. 2F View Fig ) bilobed; that of concave side ( Fig. 2G View Fig ) oval, not segmented, lacking posterolateral point. Oostegites 2–5 of concave side all separated and aligned. Seven pereopods on each side of body; on both sides, first two pairs of pereopods adjacent to head: both pairs large and with all articles distinct, basis rectangular, ischium trapezoidal and shorter than basis, merus trapezoidal with short spines on inferior margin, carpus triangular, propodus ovate, dactylus stout ( Fig. 2H View Fig ). Pereopods 3 and 4 of convex side widely separated by expanded part of pereomere ( Fig. 1A View Fig ). Pereopods 5–7 present on posterior margin of pleon, covered by left pleopod 1 ( Fig. 2I View Fig ). Pereopods 3–7 of concave side tightly clumped ( Fig. 1A View Fig ).

Pleon ( Fig. 1 View Fig A–C): all pleomeres fused dorsally; pleomeres 1–4 distinct laterally and ventrally; pleomere 1 bearing single midventral tubercle, pleomere 2 with two similar ventral tubercles; pleomere 5 (= pleotelson) in form of simple bulb visible only in ventral view. Four pairs of large lamellar lateral plates and four pairs of pleopods present, all well-developed; lateral plates ( Fig. 1A View Fig ) irregularly oval, shorter posteriorly; those on concave side smaller than those opposite. Pleopods ( Fig. 1C View Fig ) uniramous, first two large, lanceolate; pleopods 3 and 4 slightly bilobed and smaller than pleopods 1 and 2. Uropods absent.

Description of allotype male (KMNH IvR 500,728). Body ( Fig. 3 View Fig A–C) small, about 29% as long as female, elliptical in general outline; body width 54% of body length, with maximal width at pereomere 5.

Head ( Fig. 3A View Fig ) distinct from pereomere 1, semicircular, with tiny medial notch on anterior margin, slightly longer than pereomere 1. Eyes absent. Antenna 1 ( Fig. 3D View Fig ) short, of 3 articles; articles 2 and 3 each with tuft of long seta distally. Antenna 2 ( Fig. 3D View Fig ) of 7 articles, surpassing midpoint of pereomere 1.

All pereomeres ( Fig. 3 View Fig A–C) distinctly demarcated dorsally, lacking tubercles ventrally; lateral margins convex; pereomere 7 and pleon distinct laterally on both sides, fused in central region both dorsally and ventrally. Pereopods ( Fig. 3E View Fig ) all of similar size and structure; all articles similar to those of female in segmentation.

Pleon ( Fig. 3A, C View Fig ) completely fused, semi-ovoidal, representing 27% of whole body length; posterior margin rounded, smooth, without anal tube or long taper. Pleopods and uropods absent.

Etymology. Named in honour of the collector, Dr. Junji Okuno, in recognition of his contribution to the knowledge of the hinge-beak shrimps.