Petalosarsia ovalis Akiyama & Gerken, 2012, sp. nov.
Creators: name: Akiyama, Tadashi
name: Gerken, Sarah
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Cumacea
Pseudocumatidae
Petalosarsia
Petalosarsia ovalis

description: Petalosarsia ovalis sp. nov.
(Figs. 4–6)
Material examined. Holotype ovigerous female, 4.20 mm (NSMT-Cr 22067), Okinawa Trough, East China Sea, 29°29.7ˏN, 127°46.8ˏE – 29°30.4ˏN, 127°46.8ˏE, 1018–1027 m (KT-04-23, St. D1-b'), 12 October 2004. Paratypes; 1 subadult male, 4.90 mm (NSMT-Cr 22068), Okinawa Trough, 26°15.16ˏN, 125°17.22ˏE – 26°13.85ˏN, 125°18.43ˏE, 991– 955 m (KT-02-3, St. E-2), 26 April 2002; 1 preparatory female, 4.39 mm (NSMT-Cr 22069), Okinawa Trough, 24°56.19ˏN, 124°54.39ˏE – 24°56.71ˏN, 124°56.18ˏE, 1012– 1006 m (KT-02-3, St. C-2), 27 April 2002; 1 ovigerous female, 3.98 mm (NSMT-Cr 22070), off Aguni Isl., Okinawa Trough, 26°24.94ˏN, 127°20.46ˏE – 26°25.68ˏN, 127°20.12ˏE, 734–761 m (KT-08-33, St. AG5-2), 17 December 2008; 1 ovigerous female, 3.84 mm (NSMT-Cr 22071), west of Koshiki Isles., 31°36.86ˏN, 128°28.35ˏE, 534 m (N251, St. M), 14 November 2007; 1 preparatory female, 4.03 mm (NSMT-Cr 22072), East of Ryukyu Island, 26°36.39ˏN, 128°27.33ˏE – 26°37.09ˏN, 128°28.14ˏE, 513–724 m (KH-05-1, St. PS-9), 25 May, 2005; 1 preparatory female, 3.56 mm (NSMT-Cr 22073), west of Kyusyu Island, 32°09.11ˏN, 129°31.25ˏE, 495 m (N282, St. B-1), 7 June, 2009; 1 subadult male, 4.07 mm (NSMT-Cr 22074), west of Kyushu Island, 31°42.93ˏN, 128°35.72ˏE – 31°42.05ˏN, 128°34.76ˏE, 498–501 m (N237, St. F-2), 9 May, 2007.
Description. Ovigerous and preparatory females (Figs. 4, 5). Body well calcified, covered with minute scale like sculpture. Carapace (Figs. 4 A, B) oval seen from above, length 1.03–1.15 times width, length 1.55–1.78 times depth, length 0.28–0.30 times total body length. Width of hind margin 0.71–0.77 times (ovigerous females) and 0.58–0.65 times (preparatory females) greatest width of carapace. Dorsal surface flat, with shallow depressions, surrounded by a pair of prominent but dull dorsolateral carina running for entire length of carapace and a transverse ridge near hind margin; anterior portion with 3–6 minute teeth; just below anterior portion of dorsolateral carina with shallow sulcus; frontal margin of pseudorostral lobes, between anterior end of dorsolateral carina, 0.45–0.49 times greatest width of carapace; ventral margin smooth, anterolateral angle and antennal notch obsolete; pseudorostrum short and truncate, 0.08–0.11 times length of carapace. Width of small, triangular eye lobe 0.09– 0.10 times width of carapace. Pereon 0.60–0.66 times (ovigerous females) and 0.52–0.59 tomes (preparatory females) carapace length. Pleon 0.53–0.55 times total body length.
Antenna 1 (Fig. 4 C) 1st article of peduncle 1.25–1.42 times combined length of 2nd and 3rd articles; distal end of 2nd article fringed with thin, broad collar surrounding basal region of 3rd article; main flagellum of 3 articles, 0.53–0.56 times basal article of peduncle; 1st article of main flagellum 1.23–1.46 times distal 2 articles combined; accessory flagellum minute. Antenna 2 (Fig. 4 D) of 2 articles, with a plumose seta on distal end of each article. Maxilliped 1 (Fig. 4 H) with 1 branchial lobule; basis shorter than distal segments together. Maxilliped 2 (Fig. 4 I), basis 1.20–1.27 times combined length of following 4 articles, with thin plate on ventral surface and with a short seta near proximal end; blunt spines absent near distal end of basis. Maxilliped 3 (Fig. 4 J), basis 1.10–1.14 times distal articles together, with 1–3 plumose setae on inner margin; carpus with hyaline lamella on inner margin.
Pereopod 1 (Fig. 4 K), basis 1.14–1.27 times combined length of ischium and carpus, with 3–5 plumose setae on inner margin; length of carpus 1.9–2.1 times width, 3.0–3.35 times dactylus length, 0.68–0.75 times basis length. Pereopod 2 (Fig. 4 L), basis, 0.7–0.9 times distal articles together, with 1–3 long plumose setae and several short ciliate setae on inner margin; exopod short, not reaching distal end of basis. Pereopod 3 (Figs. 5 A, B), basis slender, 2.0–2.4 times combined length of distal articles; plumose setae on inner and outer margin very small; biarticulate exopod present or absent except for a pair of remnant naked setae. Pereopod 4 (Fig. 5 C, D), basis slender, 1.2–1.6 times remaining distal articles; setae and exopod similar to pereopod 3. Pereopod 5 (Fig. 5 E), basis 0.8–1.0 times distal articles together.
Uropod (Fig. 5 F), peduncle 1.02–1.19 times pleonite 6 length, 0.54–0.59 times exopod length; exopod 0.78– 0.85 times endopod, with a short seta on inner margin and a short terminal seta; endopod inner margin serrated, with 3–4 spiniform setae on inner margin and 2 terminal setae. Telson semicircular, 0.33–0.36 times length of pleonite 6 (Fig. 5 F).
2 subadult males (Fig. 6). Overall appearance similar to preparatory females. Carapace length 0.29–0.30 times total body length, length 1.18 times greatest width and 1.83 –1.92 times depth; width of hind margin 0.57–0.60 times greatest width of carapace; dorsolateral carina blunt, with 3–7 teeth; frontal margin 0.50–0.53 times greatest width; pseudorostrum 0.089 times length of carapace; width of eye lobe 0.088–0.104 times greatest width of carapace. Pereon 0.55–0.58 times carapace. Pleon 0.52–0.55 times total body length, with 2 pairs of pleopods.
Main flagellum of antenna 1 of 5 articles (Fig. 6 C); accessory flagellum of 3 articles. Antenna 2 (Fig. 6 D), peduncle with 2 plumose setae. Maxilliped 3 (Fig. 6 E), basis 1.3–1.4 times length of remaining distal articles.
Pereopod 1(Fig. 6 F), basis 1.46 times combined length of ischium and carpus; carpus 1.8–1.9 times its width and 3.1–3.3 times dactylus length. Pereopod 2 (Fig. 6 G), basis 1.0–1.1 times remaining distal articles; dactylus subequal to carpus. Pereopods 3 and 4 (Fig. H, I), basis 2.4, 1.4–1.5 times remaining distal articles respectively, with developed exopods. Pereopod 5 (Fig. 6 J), basis 0.8–0.9 times distal articles combined. Pleopod 1 and 2 (Fig. 6 K, L), outer and inner rami fused for about half of their length, with undeveloped setae; peduncle with no seta on margin.
Uropod (Fig. 6 M), peduncle 1.06–1.12 times pleonite 6 length, 0.52 times exopod length, and 0.42–0.43 times endopod length; exopod 0.81–0.82 times endopod length; endopod with 4 spiniform setae on inner margin. Telson semicircular, 0.42–0.47 times pleonite 6 length.
Etymology. The species name refers to the oval shape of the carapace as seen from above.
Distribution. Off Kyushu and Nansei Islands, East China Sea, 495–1012 m depth.
Remarks. The overall appearance of the new species resembles P. brevirostris Gamô, 1986 and P. ryukyuensis sp. nov., but is distinguishable from these two species by (1) dorsolateral carina of carapace blunt for entire length, (2) frontal margin and hind end of carapace narrow, resulting in oval shape of carapace from dorsal view, (3) small eye lobe, (4) basis of maxilliped 2 in females without spines near distal end, (5) pereopod 1 with narrower carpus and shorter dactylus, (6) exopod of pereopod 2 in females does not reach distal end of basis, and (7) pereopod 3 and 4 with only reduced plumose setae on inner and outer margin.
description: Published as part of Akiyama, Tadashi & Gerken, Sarah, 2012, The Cumacean (Crustacea: Peracarida) Genus Petalosarsia (Pseudocumatidae) from the Pacific Ocean, pp. 1-35 in Zootaxa 3320 on pages 7-11, DOI: 10.5281/zenodo.212026