Campylaspenis pisum (Vassilenko & Tzareva, 2004)

(Figs. 4–6)

Campylaspis pisum, Vassilenko & Tzareva, 2004: 13–16, Figs. 7–8. Akiyama, 2014: 161.

Diagnosis. Females: Carapace compressed antero-posteriorly; each side with three distinct oblique ridges running parallel; 1st oblique ridge branch and re-unite on dorsal surface, making encircled region; pseudorostrum short, 0.04–0.07 times carapace length, upturned; eye lobe semicircular; frontal lobe with distinct transverse ridge. Maxilliped 3 basis inner distal corner projected; inner and outer margins of merus and carpus serrated, inner margin of propodus serrated. Pereopod 1 basis inner distal corner projected. Uropod peduncle 0.8 times pleonite 6, 1.8–2.3 times exopod, 1.9–2.3 times endopod; exopod 0.9–1.0 times endopod. Male. Pereonite 5 with a pair of large penial lobes; pleon with lateral groove; antenna 2 exceeding posterior end of pleon; uropod peduncle 0.8 times pleonite 6, 2.4 times exopod and 1.9 times endopod.

Material examined. 14 ovigerous and preparatory females, 1 adult and 4 subadult males, 11 juveniles (including dissected 4 ovigerous females, 2.9–3.4 mm, 1 preparatory female, 3.2 mm, 1 adult male 3.6 mm) (NSMT Cr-22780), off Kasumi, northern coast of Hyogo prefecture, Honshu, the Sea of Japan, 35°46.11΄N, 134°30.94΄E–35° 46.57΄N, 134° 32.09΄E, 203–205 m (KT-11-9, St. K 2), 3 June 2011; 4 females, 2 subadult males, 9 juveniles (including dissected 1 ovigerous female, 3.2 mm) (NSMT-22779), off Toyama, northern coast of Honshu, 37°28.77΄N, 137°29.07΄E–37°29.53΄N, 137°28.63΄E, 207–258 m (KT-11-9, St. T2), 31 May 2011; 1 subadult male, off Noto Peninsula, 37°57.06΄N, 136°56.60΄E–37°57.04΄N, 136°58.23΄E, 201–203 m (KT-11-9, St. N 2), 1 June 2011.

Description. 4 ovigerous females, 2.9–3.4 mm; 2 preparatory females, 3.2, 3.4 mm. Carapace (Fig. 4A, B) 0.35– 0.40 times total body length, 1.18–1.29 times as width and 1.33–1.46 times depth, covered with short setae; each side with 3 distinct oblique ridges running parallel, 1st oblique ridge branch and re-unite on dorsal surface, making encircled region; 1st and 2nd oblique ridges connected by a short vertical ridge near lower margin of carapace; pseudorostrum 0.03–0.07 times carapace length, upturned; width of round eye lobe 0.11–0.13 times carapace width, 0.9–1.2 times eye lobe length; frontal lobe with distinct transverse ridge (Fig. 7A, B); antennal notch obsolete; lower margin serrated. Pereon (Fig. 4A) 0.48–0.70 times carapace length. Pleon (Fig. 4A) 0.38–0.42 times total body length; pleon with weak lateral process on each side; pleonite 6 (Fig. 5G) 0.8 times as long as wide.

Antenna 1 (Fig. 4C), peduncle almost naked; basal article curved, 1.0–1.3 times articles 2 and 1.0–1.3 times article 3; article 3 0.9–1.1 times article 2; main flagellum tri-articulate, 0.8–0.9 times peduncle article 3; basal article 1.0 times combined length of articles 2 and 3; accessory flagellum uni-articulate, 0.3–0.4 times main flagellum article 1. Antenna 2 (Fig. 4D) uni-articulate, with 6 tubercles on distal margin. Left and right mandibles (Fig. 4E) broad at base; with robust 3 and 4 setae with many minute tubercles, respectively; molar process styliform, 3- or 4-dentate; lacinia mobilis 4-dentate; incisor process 5- or 6- dentate. Labium (Fig. 4F) with short simple setae on tip. Maxilla 1 (Fig. 4G) outer endite with 9 simple or dentate robust setae, lower 2 simple setae a little apart from the remaining setae; narrow endite with 5 ciliated, non-dentate setae; palp with terminal seta. Maxilla 2 (Fig. 4H) narrow distally, with 3 terminal and 1 subterminal setae. Maxilliped 1 (Fig. 4I, J) with 4–6 branchial lobules (Fig. 4I); merocarpus with 3–4 simple setae on distal region and 3–4 short simple seta on inner margin; dactylus minute, 0.04–0.07 times merocarpus length (Fig. 4J). Maxilliped 2 (Fig. 4K) basis 0.7–0.8 times distal articles together; ischium with plumose seta on inner distal corner; carpus with 2 tubercles and 2 simple setae on inner margin; propodus long, with 1 long terminal spines; dactylus with 3 long terminal spines. Maxilliped 3 (Fig. 5A) basis 0.6– 0.7 times distal articles together, inner distal corner projected, with 1–2 plumose and 0–3 simple setae; outer distal corner with 0–2 long plumose setae; ischium with 2–3 simple setae on inner margin; merus 1.1–1.3 times combined length of carpus and propodus, with 7–9 teeth and 7–9 simple setae on inner margin, and 2–4 teeth and plumose seta on outer margin; carpus with 3–5 teeth and 2–3 simple setae on inner margin, 2–3 teeth and a plumose seta on outer margin; propodus with 4–6 teeth and 2–3 plumose setae on inner margin and plumose seta on outer distal corner; dactylus with 3 terminal setae.

Pereopod 1 (Fig. 5B) basis 0.7–0.8 times distal articles together, inner distal corner projected, with 2 plumose setae, outer distal corner with 0–1 plumose setae; ischium with 1–2 plumose setae on inner margin; merus 0.7–0.8 times combined length of carpus and propodus, with 1–2 plumose and 2–4 simple setae on inner margin, with 2–3 plumose seta on outer margin; carpus with 4–5 teeth and 2 simple setae on inner margin, 3 teeth and 2 plumose setae on outer margin; propodus with 2–3 teeth and 2 simple setae on inner margin, 3 plumose setae on outer margin; exopod flagellum of 4 articles. Pereopod 2 (Fig. 5C) basis 0.5 times distal articles together, with plumose seta on inner distal corner; dactylus 1.4–2.0 times carpus, with 9–10 setae. Pereopod 3 (Fig. 5D) basis 1.2–1.4 times distal articles together, with 2–3 plumose on lateral margin. Pereopod 4 (Fig. 5E) basis 0.9–1.0 times distal articles together. Pereopod 5 (Fig. 8F) basis 0.5–0.6 times distal articles together. Terminal setae on dactylus of pereopods 3–5 fused to the articles.

Uropod (Fig. 5G) peduncle 1.7–2.0 times pleonite 6 length, 1.8–2.4 times exopod, 1.9–2.3 times endopod, serrated on inner margin; exopod 0.9–1.0 times endopod, with long simple terminal seta; endopod uni-articulate, with 3 spiniform setae on inner margin and long terminal seta.

Adult male, 3.6 mm (Fig. 6). Carapace (Fig. 6A, B) 0.37 times total body length, 1.46 times width, 1.79 times depth, with few short setae; ridges on carapace similar to females; pseudorostrum (Fig. 6A, B) 0.06 times carapace length; width of eye lobe 0.13 times carapace width, 1.2 times eye lobe length; corneal lenses absent; antennal notch shallow (Fig. 6C); lower margin of carapace serrated. Pereon (Fig. 9A, B) 0.66 times carapace length; pereonite 5 with large penial lobes (left lobe shown in Fig. 6A, D), longer than basis of pereopod 5. Pleon (Fig. 6A) 0.39 times total body length, with lateral grooves; pleonite 6 (Fig. 6M) 0.8 times as long as wide.

Antenna 1 (Fig. 6E), peduncle basal article 1.2 times article 2 and 1.3 times article 3; article 3 0.9 times article 2. Main flagellum tri-articulate, 1.0 times peduncle article 3, with 1 aesthetasc on articles 2 and 3; accessory flagellum uni-articulate 0.4 times main flagellum article 1. Antenna 2 (Fig. 6F) peduncle articles 5 2.0 times article 4; flagellum of 20 articles, exceeding posterior end of pleon. Maxilliped 3 (Fig. 6G) basis 0.8 times distal articles together, inner distal corner with 2 plumose and 1 simple setae, outer distal corner with 2 plumose setae; merus 0.9 times combined length of carpus and dactylus, with 8 teeth and 8 short simple setae on inner margin and 5 teeth and plumose seta on outer margin; carpus with 3 teeth and 3 simple setae on inner margin, with 3 teeth and plumose seta on outer margin; propodus with 4 teeth and 3 plumose setae on inner margin and plumose seta on outer distal corner; dactylus with 3 terminal setae; exopod flagellum 5-articulate.

Pereopod 1 (Fig. 6H) basis 0.8 times distal articles together, inner distal corner with 2 long plumose setae, outer distal corner with plumose seta; merus 0.7 times combined length of carpus and propodus, with 2 plumose and 3 simple setae on inner margin, 4 teeth and 2 plumose setae on outer margin; carpus with 2 teeth and 3 simple setae on inner margin, with 1 tooth and 2 plumose setae on outer margin; propodus with 3 teeth and 2 simple setae on inner margin, with 1 tooth and 2 plumose setae on outer margin; exopod flagellum 5-articulate. Pereopod 2 (Fig. 6I) basis 0.6 times distal articles together, with plumose seta on inner and outer distal corner, respectively; dactylus 1.9 times carpus, with11 setae; exopod flagellum 6-articulate. Pereopod 3 (Fig. 6J) basis 1.4 times distal articles together; exopod flagellum 6-articulate. Pereopod 4 (Fig. 6K) basis 1.1 times distal articles together; exopod flagellum 6- articulate. Pereopod 5 (Fig. 6L) basis 0.7 times distal articles together.

Uropod (Fig. 6M) peduncle 2.7 times pleonite 6, 2.4 times exopod and 1.9 times endopod, with 9 plumose or ciliated setae on inner margin and 5 simple setae on ventral surface; exopod 0.8 times endopod, with 2 terminal and 2 sub-terminal setae; endopod uni-articulate, with 9 spiniform setae on inner margin and terminal seta.

Remarks. This species, originally described as Campylaspis pisum based on female specimens collected from northern coast of the Sea of Japan, 42°40΄9″N, 135°16΄8″E, 865–950 m, (Vassilenko and Tzareva, 2004), is transferred to the genus Campylaspenis due to the presence of the large penial lobes in the adult male specimen. Other morphological characters of the Japanese specimens agree with the original description by Vassilenko and Tzareva.

Campylaspenis pisum is similar to C. sigeogamoi, another Campylaspenis species from the Sea of Japan. Campylaspenis pisum is distinguished from C. sigeogamoi by (1) a transverse ridge present on frontal lobe of carapace (not present in C. sigeogamoi), (2) pseudorostrum very short, 0.035 –0.072 times carapace length, upturned (pseudorostrum not so short, 0.11–0.13 times carapace length, not upturned in C. sigeogamoi).

Campylaspenis pisum is very similar to Campylaspis brevirostris Akiyama, 2014 except for the presence of penial lobes in males. Upturned pseudorostrum of both species is very short, 0.035 –0.072 times carapace length in C. pisum and 0.034 –0.039 times in C. brevirostris (based on the drawings of the 5 type specimens described in Akiyama, 2014). However, in addition to the morphological characters in Akiyama (2014), Campylaspenis pisum is distinguished from Campylaspis brevirostris by (1) relative length of basis to combined length of distal articles in maxilliped 3 and pereopod 1 are 0.6–0.8 for maxilliped 3 and 0.7–0.8 for pereopod 1 in females (0.9–1.0 for maxilliped 3 and 1.0–1.1 for pereopod 1 in C. brevirostris), (2) finger-like process absent on propodus of maxilliped 3 in adult male (present in C. brevirostris, Fig. 6B, C).

Distribution. Russian and Japanese coast of the Sea of Japan, 865–950 m in Russia and 201–258 m in Japan.