Bathycopea oculata Shimomura, 2008, sp. nov.

Bathycopea oculata sp. nov.

Figs 1–7

Material examined. Holotype. Male, 2.6 mm (KMNH IvR 700,033), dissected and mounted on glass slides, St.4-2, off Cape Toi, Miyazaki Prefecture, 31º26.20’N, 131º39.84’E- 31º25.65’N, 131º39.62’E, 528– 523 m, sand, 3 m ORE beam trawl, TRV Toyoshio-maru, 18 May, 2004, collected by MS.

Paratypes. Ovigerous female, 4.5 mm (KMNH IvR 700,030), dissected and mounted on glass slides, ovigerous female, 4.5 mm (KMNH IvR 700,031), dissected and mounted on aluminum stubs for SEM observation, ovigerous female with 17 juveniles, 4.5 mm (KMNH IvR 700,032), dissected and mounted on glass slides, TRV Toyoshio-maru, St. 9, off Mi-shima Island, Yamaguchi Prefecture, Sea of Japan, 34º47.40’N, 131º19.80’E, 99 m, sand and mud, sledge net, 18 November, 1999, collected by MS; 3 non-ovig. females, 1.7 mm (KMNH IvR 700,252), 1.4 mm (KMNH IvR 700,253), 1.2 mm (KMNH IvR 700,254), whole specimens in glass bottle, St. X(5’), off Amami-oshima, Kagoshima Prefecture, 28º22.37’N, 129º15.97’E- 28º22.28’N, 129º15.43’E, 290 m, sand, 3 m ORE beam trawl, 21 May, 2004, collected by Dr. S. Ohtsuka.

Diagnosis. Body dorsally smooth. Pereonites 1 to 7 increasing in width posteriorly, without dorsal keels. Pereonite 2 broadly projected anterior-laterally. Pleonite 1 strongly arched dorsally; lateral margins broadly rounded. Pleotelson gradually decreasing in width posteriorly, with single dorsal carina. Eye lobes well-developed, with 43–57 ommatidia. Uropod moderately broad, about 4–4.7 times as long as width, with short tooth medial-laterally, without large serrations on lateral margin. Epistome triangular in shape, apically rounded, not surpassing frontal margin of antennule peduncular article 1; margins straight. Pereopod 1: distal corner of carpus blunt, broadly rounded. Pereopod 2 in male: merus and carpus shorter than ischium; propodus about 2.9 times as long as carpus, slightly curved inward, without proximal projections, with 3 sensory robust setae ventral-proximally and simple seta ventral-distally, ventral-distally denticulated; dactylus as long as propodus, curved inward, with few short simple setae.

Description of the holotype male. Body (Fig. 2 A, B) about 1.6 times as long as maximum width. Head (Fig. 2 A) partly fused with pereonite 1. Pleon (Fig. 2 A, B) slightly broader than pereonite 7. Pleotelson (Fig. 2 A) about 1.2 times as broad as long, apically rounded; central part distinguished by ridge smooth and flattened dorsally. Uropod (Fig. 2 A) marginally crenulated, with many short setae laterally.

Antennule (Fig. 2 A, D) peduncular article 1 about as long as broad, dorsally with 4 short setae and 11 simple scales, cuticularized on medial margin; article 2 with 5 short setae and few simple scales, strongly ridged distal-dorsally, cuticularized on medial margin; article 3 longest, with few short medial, lateral and dorsal setae. Flagellum of 8 articles, shorter than peduncle: article 1 minute; article 2 shorter than peduncular article 2; article 3 half as long as article 2, with medial seta; articles 4 to 8 decreasing in length gradually, each articles with some simple setae and aesthetascs distally.

Antenna (Fig. 2 C, E) article 1 with fine setae laterally; article 2 broadest at nearly proximal base, with several setae medially and simple seta laterally and distally; article 3 longest and widest, with 10 setae medially and 1 setae and many fine setae laterally; article 4 as long as article 2, with 9 setae medially and 2 simple setae laterally. Flagellum about as long as peduncle: articles 1–3 with some simple scales; article 1 slightly longer than peduncular article 4, with many setae medially and few setae laterally; article 2 about 0.3 times as long as article 1, with 5 setae medially; article 3 as long as article 2, with 6 medial setae; articles 4 to 10 decreasing in length, each with some simple setae.

Left mandible (Fig. 2 F) article 1 of palp robust, with some setulated scales, with simple seta ventrally; article 2 about 1.5 times as long as article 1, with 5 pectinate setae, and some setulated scales; article 3 shortest, with 8 pectinate setae. Incisor slender, widest at middle part. Right mandible (Fig. 2 G): article 1 of palp robust, with some setulated and simple scales; article 2 with 4 pectinate setae, some simple and setulated scales; article 3 about 0.3 times as long as article 2, with 7 pectinate setae.

Maxillule (Fig. 2 H) with mesial lobe bearing 1 apical long and few fine setae; lateral lobe with 6 apical stout serrate and 2 simple setae, and few setulated scales.

Maxilla (Fig. 2 I) with mesial lobe bearing 2 apical simple spines and 3 setulated scales; middle lobe with 4 apical pectinate setae; lateral lobe with 4 apical simple setae.

Maxilliped (Fig. 3 A) article 1 with ventral seta and few simple scales; article 2 trapezoidal, about 3 times as long as article 1, with 1 medial seta, and setulated scale and many simple scales; article 3 as long as article 2, with 2 long distal-medial setae and 4 setulated and 4 simple scales; article 4 narrow, slightly shorter than article 3, with 3 distal-medial and 2 lateral setae, and 6 setulated scales; article 5 minute, with 4 apical long and few lateral short setae; endite trapezoidal, bearing many fine marginal setae, with many setulated and simple scales ventrally, and coupling hook medially.

Pereopod 1 (Fig. 2 J) basis robust, dorsally with 8 short setae; ischium about 0.7 times as long as basis, without setae; merus trapezoidal, about half as long as ischium, without setae; carpus as long as merus, distally rounded, distally with many short setae; propodus with row of triangular robust setae on palm, proximalmedially with some setulated and simple scales; dactylus stylet-like, with 2 blunt teeth proximal-ventrally, reaching to carpus, without setae.

Pereopod 2 (Fig. 2 K) basis with short simple seta and many simple scales; ischium about 0.3 times as long as basis, with few simple scales; merus subtriangulate, shorter than ischium, with simple seta ventral-distally; carpus trapezoidal, about as long as merus, with 2 simple setae medially, ventral-distally denticulated; propodus robust, slightly curved inward, with 3 robust sensory setae ventral-proximally and simple seta ventral-distally, ventral-distally denticulated; dactylus slender, about as long as propodus, curved inward, with 2 ventral and 2 apical short simple setae.

Pereopod 7 (Fig. 3 C) basis with 12 short ventral and 4 dorsal setae; ischium about 0.3 times as long as basis, without setae; merus about twice as long as ischium, with 1 long and 6 short setae ventrally, 2 simple setae dorsal-distally and simple seta medial-distally and lateral-distally; carpus longer than merus, distal-ventrally with 2 long setae and broom seta, and with 2 setae dorsal-distally; propodus about 0.9 times as long as carpus, with 3 long distal-ventral, 1 long ventral and 2 long distal-dorsal setae; dactylus narrowest article; distally with 3 short simple seta and unguis

Pleopod 1 (Fig. 3 D) with some simple scales ventrally: peduncle about 2.8 times as broad as long, with 3 coupling hooks distal-medially and few fine setae medially, and many short setae laterally; endopod about 2.1 times as long as peduncle, slightly broader than long, bearing many long plumose marginal setae and fine simple setae; exopod narrower than endopod, longer than endopod, with many long plumose setae and many fine setae marginally and few simple short setae ventrally.

Pleopod 2 (Fig. 3 E) with some simple scales ventrally: peduncle about 2.1 times as broad as long, with 3 coupling hooks distal-medially and many fine setae marginally; endopod moderately narrow, triangulate, about 2.3 times as long as broad, 3.6 times as long as peduncle, bearing some long plumose and fine simple setae; appendix masculina as long as endopod, with fine microtrichs ventrally; exopod ovate, about 0.6 times as long and about 0.7 times as wide as endopod, with many long plumose and many fine setae marginally.

Pleopod 3 (Fig. 4 A) with some simple scales ventrally: peduncle longer than those of pleopods 1 and 2, about 2.1 times as broad as long, with 2 coupling hooks distal-medially and many fine short setae marginally; endopod broad, about 2.3 times as long as peduncle, longer than broad, bearing 4 short plumose setae apically; exopod articulated, bearing many plumose marginal setae.

Pleopod 4 (Fig. 4 B): endopod longer than exopod, tapering to apex, with simple seta apically; exopod pyriform in shape, about twice as long as broad, bearing simple seta laterally.

Pleopod 5 (Fig. 4 C): endopod about 2.3 times as long as broad, with 2 notches proximal-medially and many fine setae distal-medially; exopod as long as endopod, with simple seta medially and many fine setae distal-medially.

Description of the paratype female. Pereopod 2 (Fig. 3 B): basis with 6 short ventral and 1 dorsal-distal setae; ischium about 0.3 times as long as basis, without setae; merus as long as ischium, with 1 long and many fine setae ventrally and 2 short setae dorsally; carpus longer than merus, with 2 long ventral-distal and many fine ventral setae; propodus as long as carpus, with 2 long ventral and 3 dorsal-distal setae; dactylus narrowest article; with 2 distal setae and curved unguis.

Pleopod 2 (Fig. 3 F) with many simple scales ventrally: peduncle about 2.1 times as broad as long, with 3 coupling hooks distal-medially and many fine setae marginally; endopod broad, about 3 times as long as peduncle, longer than broad, bearing many long plumose marginal setae and fine simple setae; exopod ovate, about 0.8 times as long as endopod, with many long plumose and many fine setae marginally.

Additional notes on paratype. One paratype female was observed with SEM (Figs. 5–7).

Body (Fig. 5 A–C) moderately smooth: setation scattered. Cephalon (Fig. 5 A) completely fused with pereonite 1 at middle part. Dorsal setae (Fig. 5 E) on pereon branched, arising from sheath. Marginal setae on uropods (Fig. 5 D) penicillate. Dorsal-distal part of antennule peduncular article 2 (Fig. 4 F) strongly ridged. Incisors of right mandible (Fig. 6 A) with many scales having row of short setae; lacinia mobilis with 2 cusps, branched at its base; molar process setulated distally. Incisor with left mandible (Fig. 6 B) with many scales, with setulate robust seta and molar process. Mandibular palp (Fig. 6 C): article 2 with 23 curved simple scales, marginally setulated; article 3 triangulate, distally pointed, without scales. Maxilliped palp (Fig. 6 D): scales on article 2 nearly straight, without setae; scales on articles 3 and 4 nearly straight, with long setae; article 5 without scales. Coupling hook of maxilliped (Fig. 6 E) curved ventrally; inner margin denticulate. Pereopod 1 (Figs. 6 F, 7A, B): palm of propodus with row of many short simple setae and triangulate setae; scales of propodus with many setae agglutinated on basis. Pereopod 7 (Fig. 7 C, D): distal setae on carpus feather-like, broad apically; scales simple without setae. Pleopod 1 (Fig. 7 E, F): plumose setae consisting of robust trunk and many thin, membranous setae; scales rudimentary, without setae.

Colour. Colour in life (Fig. 1) yellowish white, with dark brown chromatophores. Eyes: pigment colour brownish red.

Remarks. Both Bathycopea oculata sp. nov. and Bathycopea daltonae from the shallow-water habitats in California have eyes. B. oculata is, however, distinguished from B. daltonae by the following features (those of B. daltonae in parentheses): uropod about 4–4.7 times as long as width, with short tooth medial-laterally (5.4 times as long as width, without short tooth medial-laterally) and pleotelson gradually decreasing in width posteriorly (more sharply decreasing).

Etymology. From the Latin oculus, referring to the well-developed eyes with many ommatidia.