Iphinoe wakasaensis, Akiyama, 2025

Iphinoe wakasaensis sp. nov.

( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Diagnosis. Ovigerous female. Carapace 0.25–0.27 times total body length, 2.0–2.3 times as long as wide, 2.2–2.4 times depth. median dorsal ridge with 17–27 teeth present for entire length of carapace; width of round eye lobe 0.11–0.14 times carapace width, 0.8–0.9 times eye lobe length; antero-lateral angle pointed, succeeded by 12–20 teeth on anterior half of inferior margin of carapace. Antenna 1 peduncle article 1 1.08–1.48 times as long as article 3. Pereopod 1 propodus with long simple seta on distal end; dactylus 0.90–1.11 times as long as carpus. Uropod peduncle with spiniform setae. Adult male. Carapace with weak median dorsal ridge running for anterior half of carapace, with 2–5 distinct and 5–10 minute spines; width of eye lobe 0.17–0.19 times carapace width, 0.8–1.0 times eye lobe length; antero-lateral angle forming obtuse angle, succeeded by 11–19 teeth on anterior half of inferior margin of carapace. Antenna 1 main flagellum article 1 with 2–4 aesthetascs.

Type material. Holotype ovigerous female, 9.7 mm ( NSMT Cr-32962), NE off Nomuro-zaki , western Wakasa Bay, the Sea of Japan, 35°45.26'N, 135°20.88'E – 35°45.04'N, 135°21.03'E, 99.2–100 m, 27 May 2013, Collected by H. Saito and Y. Kai. GoogleMaps

Paratypes. 30 ovigerous females, 26 preparatory females, 37 adult males, 17 subadult males, 10 juveniles (4 ovigerous females, 8.7–9.8 mm and 3 adult males, 9.3–10.3 mm dissected) ( NSMT Cr-32963), same locality and date as the holotype female; 15 ovigerous females, 44 preparatory females, 10 adult males, 11 subadult males, 6 juveniles, 12 manca larvae (1 ovigerous female, 7.9 mm dissected) ( NSMT Cr-32964), NE off Nomuro-zaki , western Wakasa Bay, the Sea of Japan, 35°45.09'N, 135°20.44'E – 35°45.09'N, 135°20.17'E, 96–96.3 m, 2 September 2010, collected by H. Saito and Y. Kai. GoogleMaps

Other material examined. Six ovigerous females, 7.0– 7.8 mm, 3 adult males, 8.1–8.2 mm ( 1 specimen damaged), partially dissected, Enshu-nada, 34°36.11'N, 137°59.06'E – 34°36.01'N, 137°59.27'E, 113–172 m (KT-02-5, St. EN 4-2), 27 May 2002 GoogleMaps ; 3 ovigerous female, 7.3–7.7 mm, 1 preparatory female, 7.5 mm, partially dissected, western coast of Izu Peninsula , 34°50.88'N, 138°44.78'E – 34°50.77'N, 138°44.69'E, 128–136 m (KT-02-5, St. IZW- 1), 29 May 2002 GoogleMaps ; 1 ovigerous female, 7.4 mm, 2 preparatory females, 7.1, 7.7 mm, 4 adult males, 8.2–8.5 mm, partially dissected, Kumano-nada , 34°13.12'N, 136°38.98'E – 34°13.29'N, 136°39.10'E, 107–109 m (KT-03-1, St. KN-3), 7 April 2003, collected by T. Sasaki GoogleMaps ; 2 ovigerous females, 7.5, 8.4 mm, 1 preparatory female, 7.9 mm, partially dissected, off Kamogawa , Boso Peninsula, 34°59.11'N, 140°03.29'E – 34°59.33'N, 140°03.35'E, 104–108 m (KT-03-17, St. KG-1), 17 Nov., 2003 GoogleMaps ; 1 ovigerous female, 6.7 mm, 2 adult males, 8.0, 8.2 mm, partially dissected, off Kamogawa , 34°58.19'N, 140°05.19'E – 34°58.40'N, 140°05.12'E, 169–200 m (KT-03-17, St. KG-2), 17 Nov., 2003 GoogleMaps ; 1 ovigerous female, 7.6 mm, partially dissected, 34°17.71'N, 136°71.92'E– 34°17.61'N, 136°71.92'E, 139– 140 m, sand, 22 May, 2014, collected by H. Saito and K. Kimura.

Description. Holotype ovigerous female, 9.7 mm ( Fig. 2A–D View FIGURE 2 ). Body moderately calcified, almost naked. Carapace smooth, 0.25 times total body length, 2.0 times as long as wide, 2.3 times depth; dorsal surface with median ridge running for entire length of carapace, with 26 teeth, prominent for anterior half; pseudorostrum ( Fig.2C, D View FIGURE 2 ) 0.12 times carapace length; distal end in contact each other; width of round eye lobe ( Fig2B, D View FIGURE 2 ) 0.14 times carapace width, 0.9 times eye lobe length; antennal notch ( Fig. 2C View FIGURE 2 ) deep; antero-lateral angle pointed, lower margin of carapace with 12 teeth for anterior half of carapace. Pereon 1.08 times carapace length; pereonite 2 well developed; pereonite 3 and 4 with projection at hind margin. Pleon 0.48 times total body length; without ridges or ornaments.

Paratype five ovigerous females, 7.9–9.8 mm. Carapace 0.25–0.26 total body length, 2.0–2.1 times as long as wide, 2.2–2.3 times depth. median dorsal ridge with 18–27 teeth; pseudorostrum 0.12–0.14 times carapace length; width of eye lobe 0.11–0.12 times carapace width, 0.8–0.9 times eye lobe length; antennal notch deep; antero-lateral angle pointed, lower margin with of carapace with 13–20 teeth for anterior half of carapace. Pereon 1.01–1.08 times carapace length. Pleon 0.47–0.49 times total body length; without ridges.

Antenna 1 ( Fig. 2E View FIGURE 2 ) peduncle almost naked, article 1 weakly curved, 1.4–1.5 times as long as article 2, 1.2–1.4 times as long as article 3; article 3 1.1–1.2 times as long as article 2; main flagellum biarticulate, 0.4 times as long as peduncle article 3, article 1 2.0–2.7 times as long as article 2; accessory flagellum uniarticulate, 0.5–0.6 times as long as main flagellum article 1.

Antenna 2 ( Fig. 2F View FIGURE 2 ) biarticulate, basal article with three pappose setae on distal margin; article 2 with three broom setae distally.

Left and right mandibles ( Fig. 2G View FIGURE 2 ) with 14–15, 13 setae, respectively; lacinia mobilis tridentate; incisor process 4-dentate.

Labium ( Fig. 2H View FIGURE 2 ) distal end slightly projected narrowly, with five dentate setae.

Maxilla 1 ( Fig. 2I View FIGURE 2 ) outer endite with 12–14 spiniform setae; inner endite with one tridentate, 3–4 setulate, and one simple setae; palp with two terminal setae.

Maxilla 2 ( Fig. 2J View FIGURE 2 ) narrow endites with 6–7 setae on each; broad endite with 24–29 thin (broad at base) setae.

Maxilliped 1 ( Fig. 2K, L View FIGURE 2 ) with 16–18 branchial lobules; basis 1.3–1.5 times combined length of distal articles; carpus (numerous setae on ventral surface omitted in Fig. 2K View FIGURE 2 ), with seven thin dentate setae on inner margin; propodus with two plumose and one simple setae on inner distal corner; dactylus with three minute terminal setae.

Maxilliped 2 ( Fig. 3A View FIGURE 3 ) basis 1.7–1.9 times as long as distal articles together, with pappose seta in inner distal corner; carpus with 10–11 setae on inner margin; propodus with 9–11 simple setae on inner margin; dactylus with three terminal and two simple subterminal setae; rudimentary oostegite of coxa strongly bent, with 12–13 setae.

Maxilliped 3 ( Fig. 3B View FIGURE 3 ) basis 1.7–1.9 times as long as remaining distal articles, with 2–3 plumose seta on inner distal region, outer distal corner strongly projected reaching proximal region of carpus, with 14–16 plumose setae; ischium with 2–3 plumose setae on inner margin; merus outer distal corner projected, with 3–5 setae, inner margin with 1–2 plumose and 0–1 simple setae; carpus with 5–6 plumose setae on inner margin; propodus with 5–6 simple setae on inner margin; dactylus with 4–6 terminal setae; exopod flagellum of five articles.

Pereopod 1 ( Fig. 3C View FIGURE 3 ) basis 0.7–0.8 times as long as distal articles together, with one spine on distal end of ventral surface, outer and inner margins serrated; carpus 1.2–1.4 times as long as merus, 0.8–0.9 times as long as propodus; propodus 1.1–1.3 times as long as dactylus, with long simple seta on inner distal corner; dactylus 1.0–1.1 times as long as carpus, with four simple terminal setae; exopod flagellum of five articles.

Pereopod 2 ( Fig. 3D View FIGURE 3 ) basis 0.7 times as long as remaining articles together, with 3–4 plumose setae on outer margin; merus with large spiniform seta on inner distal corner; carpus 1.0–1.3 times as long as merus, with spiniform seta on inner distal corner; dactylus 1.4–1.8 times as long as carpus and 2.7–3.4 times as long as dactylus, with 8–12 setae.

Pereopod 3 ( Fig. 3E View FIGURE 3 ) basis 1.1–1.3 times as long as distal articles together, with one plumose and one simple setae on distal corner; ischium with one plumose and 2–4 simple setae on distal corner; carpus with 4–5 simple setae on distal region; dactylus small.

Pereopod 4 ( Fig. 3F View FIGURE 3 ) basis 0.8–0.9 times as long as distal articles together, with 5–7 plumose setae on outer margin, plumose seta on distal corner; ischium with one plumose and 4–8 simple setae; carpus with five simple setae on distal region; dactylus small.

Pereonite 5 ( Fig. 3G View FIGURE 3 ) basis 0.8 times as long as distal articles together, with 1–3 plumose setae on lateral margin, plumose seta on distal corner; ischium with plumose or simple setae on distal corner; carpus with 4–5 simple setae on distal region; dactylus small.

Uropod ( Fig. 3H View FIGURE 3 ) peduncle 1.3–1.4 times as long as pleonite 6, 1.3–1.4 times as long as exopod and 1.4–1.5 times as long as endopod, with 9–14 spiniform setae on inner margin; exopod 1.0–1.1 times as long as endopod, with four plumose setae on outer margin, 15–17 plumose setae on inner margin and apical end; endopod biarticulate, article 1 0.5–0.6 times as long as article 2; article 1 with five spiniform setae on inner margin; article 2 with 11–15 spiniform setae on inner margin and 6–8 plumose setae on outer margin and apex.

Paratype 1 preparatory female, 8.4 mm. The specimen is similar to the ovigerous females, except that the width of the posterior margin of the carapace is narrow (carapace 2.5 times as long as wide).

Paratype three adult males, 9.3–10.3 mm ( Fig. 4 View FIGURE 4 ). Body moderately calcified. Carapace ( Fig. 4A–D View FIGURE 4 ) 0.24–0.25 times total body length, 2.6–2.7 times as long as wide and 2.1–2.3 times depth; dorsal surface weakly arched, with very weak median ridge on frontal lobe; 2–5 prominent and 5–10 minute spines on median dorsal ridge; pseudorostrum 0.10–0.12 times carapace length; left and right pseudorostrum in contact at distal end; width of round eye lobe ( Fig. 4B, D View FIGURE 4 ) 0.17–0.18 times carapace width and 0.9–1.0 times eye lobe length; antennal notch ( Fig. 4C View FIGURE 4 ) shallow; anterolateral angle ( Fig. 4C View FIGURE 4 ) not pointed, succeeded by 12–18 teeth on anterior half of lower margin of carapace. Pereon 0.93–0.96 times as long as carapace; pleon 0.52–0.53 times total body length.

Antenna 1 ( Fig. 4E View FIGURE 4 ) peduncle article 1 1.5–1.6 times as long as article 2 and 1.3–1.5 times as long as article 3; article 3 1.1–1.2 times as long as article 2; main flagellum biarticulate, 0.4–0.5 times as long as peduncle article 3; article 1 2.2–2.6 times as long as article 2, with 2–4 aesthetascs; accessory flagellum biarticulate, 0.5 times as long as main flagellum article 1.

Antenna 2 ( Fig. 4F View FIGURE 4 ) peduncle article 5 3.6–4.4 times as long as article 4; flagellum exceeds posterior end of pleonite 6.

Maxilliped 3 ( Fig. 4G View FIGURE 4 ) basis 1.8–1.9 times as long as distal articles together, outer distal corner projected, with 11–19 plumose setae; ischium with three plumose setae on inner margin; merus with 0–1 plumose seta on inner margin, with 2–4 plumose setae, inner margin with one plumose and 0–1 simple setae; carpus with 5–7 plumose and 0–2 simple setae on inner margin; propodus with 3–6 simple setae on inner distal region; dactylus with 3–4 terminal setae.

Pereopod 1 ( Fig. 4H View FIGURE 4 ) basis 0.8 times as long as distal articles together, with 19–24 spiniform setae on basal region of ventral surface; carpus 1.3–1.4 times as long as merus, 0.8–0.9 times as long as propodus; propodus 1.1–1.2 times as long as dactylus, with long simple seta on distal end; dactylus 1.0–1.1 times as long as carpus, with four terminal setae.

Pereopod 2 ( Fig. 4I View FIGURE 4 ), basis 0.7–0.8 times as long as distal articles together, with 2–4 plumose setae on inner margin and 4–5 plumose setae on outer margin, 0–2 plumose setae on outer and inner distal corner; merus with robust seta on inner distal corner; carpus 0.9–1.1 times as long as merus, with robust seta on inner distal corner; dactylus 1.5–1.9 times as long as carpus and 2.9–3.3 times as long as propodus.

Pereopod 3 ( Fig. 4J View FIGURE 4 ) basis 1.2–1.3 times as long as distal articles together, with 5–6 plumose setae on outer margin; globular protrusion with 5–7 plumose setae present near inner proximal end of basis; ischium with one plumose and 3–5 simple setae on distal end; carpus with five simple setae on distal region.

Pereopod 4 ( Fig. 4K View FIGURE 4 ) basis 0.9–1.0 times as long as distal articles together, with 5–6 plumose setae on outer margin, two setae on outer distal corner; ischium with 0–2 plumose and 2–3 simple setae on distal corner; carpus with 5–6 simple setae on distal region.

Pereopod 5 ( Fig. 4L View FIGURE 4 ) basis 0.8–0.9 times as long as distal articles together, with plumose seta on lateral margin, two plumose setae on distal corner; ischium with 0–1 plumose and 3–4 simple setae on distal corner; carpus with five simple setae on distal region.

Pleopod 1 ( Fig. 4M View FIGURE 4 ) peduncle 3–4 plumose and 6–7 simple setae on inner margin; inner ramus biarticulate, outer ramus distal article with 25–29 plumose setae; inner ramus without lateral process, with 20–25 plumose setae.

Uropod ( Fig. 4N View FIGURE 4 ) peduncle 1.4–1.5 times as long as pleonite 6, 1.4–1.6 times as long as exopod, 1.5–1.6 times as long as endopod, with 54–58 stiff setulate or serrated setae on inner margin; exopod 1.0 times as long as endopod, with 24–25 plumose setae; endopod biarticulate; article 1 0.4–0.5 times as long as article 2, with 8–9 spiniform setae on inner margin; article 2 with 12–20 spiniform setae on inner margin, 5–8 plumose setae on outer margin and apex.

Remarks. Iphinoe wakasaensis sp. nov. is closely similar to Iphinoe sagamiensis but is distinguished from the latter by (1) the carapace median dorsal ridge has teeth for entire length of carapace in females, (2) the male dorsal surface of carapace has prominent and minute teeth, (3) the lower margin of the carapace is serrated in both sexes, (4) the eye lobe is smaller, (5) the anterior end of left and right pseudorostral lobes contact each other, (6) the female antenna 1 peduncle article 1 is longer than article 3, and (7) relative length of the pereopod 1 dactylus to carpus is slightly longer ( Table 1). Iphinoe wakasaensis also lives in slightly deeper habitats, 96–200 m, than I. sagamiensis at 4–101 m depths.

Iphinoe wakasaensis is similar to I. tenera from the Yellow Sea, but is distinguished from the latter by (1) the anterior portion of the carapace is without a longitudinal ridge, (2) the basis of of pereopod 1 is shorter than combined length of distal articles in females,, (3) the uropod peduncle is without long setae in females, (4) the dorsal surface of carapace has prominent and minute teeth in males, and (5) the anterolateral angle of the carapace has teeth in males ( Table 1).

Iphinoe wakasaensis is also similar to I. gurjanovae from the Chinese coast of the Yellow Sea but is distinguished from the latter by (1) the median dorsal ridge of carapace has many more teeth, (2) the uropod peduncle is without long setae in females, and (3) the dorsal surface of carapace has 2–5 prominent spines in males ( Table 1).

Distribution. Wakasa Bay, the Sea of Japan, 96– 100 m. Southern coast of Honshu, Japan, 96– 200 m.