Iphinoe suluensis, Akiyama, 2025

Iphinoe suluensis sp. nov.

( Figs 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8 )

Diagnosis. Female. Carapace 0.25–0.26 times total body length, 1.6 times as long as wide, 1.6 times depth, with 3–4 broad, weak longitudinal ridges on each side; very weak median dorsal ridge present on frontal lobe, without teeth; pseudorostrum 0.14 times carapace length, upturned, truncate at distal end; width of eye lobe 0.25–0.27 times carapace width, 2.2–2.6 times eye lobe length, slightly depressed on median frontal region; antennal notch deep, triangular; antero-lateral angle pointed, succeeded by 10–17 teeth on lower margin of carapace. Antenna 1 main flagellum very thick, article 2 with hard, curved setae. Maxilliped 3 merus greatly expanded. Pereopod 1 dactylus with robust setae directing upward. Pereopod 2 dactylus 1.4–1.6 times as long as basis. Uropod exopod with 4–8 spiniform setae on outer margin; biarticulate endopod article 1 1.7–1.9 times as long as article 2.

Type material. Holotype ovigerous female, 4.8 mm ( NSMT Cr-32966), Southern part of the Sulu Sea, Philippine , 06°05.09'N, 118°59.21'E – 06°05.21'N, 118°59.10'E, 192 m (KH-00-1, St. B 2, DG-2), 22 February 2000 GoogleMaps . Paratypes; 2 ovigerous females, 5.1, 4.8 mm, dissected, 2 preparatory females, 4.6, 5.0 mm ( 1 specimen dissected), 1 juvenile female, 4.2 mm, dissected ( NSMT Cr-32967), same locality and date as holotype specimen (KH-00-1, St. B 2, DG-2) GoogleMaps .

Description. Holotype ovigerous female, 4.8 mm ( Fig. 6A–D View FIGURE 6 ). Body moderately calcified, without setae. Carapace 0.25 times total body length, 1.64 times as long as wide, 1.61 times depth; integument with scale-like sculpture ( Fig. 6D View FIGURE 6 ), each scale encircled by net-like structure, running just below surface of integument; dorsal surface with very weak median ridge, without teeth; each side with four broad, weak longitudinal ridges ( Fig. 6C View FIGURE 6 ); pseudorostrum ( Fig. 6B, C View FIGURE 6 ) 0.14 times carapace length, upturned; distal end truncate, without setae; width of eye lobe ( Fig. 6B View FIGURE 6 ) 0.25 times carapace width and 2.6 times eye lobe length, slightly depressed at median frontal region; antennal notch ( Fig. 6C View FIGURE 6 ) deep, triangular; antero-lateral angle pointed, lower margin of carapace with 10 teeth. Pereon 0.93 times carapace length; pereonite 1 visible; pereonites 2 well developed. Pleon 0.52 times total body length; without ridges.

Paratype two ovigerous and two preparatory females. Carapace 0.25–0.26 total body length, 1.62–1.64 times as long as wide, 1.58–1.65 times depth; very weak median ridge on dorsal surface without spines, each side with 3–4 broad, weak longitudinal ridges; pseudorostrum 0.14 times carapace length; width of eye lobe 0.25–0.27 times carapace width, 2.2–2.5 times eye lobe length, slightly depressed at median frontal region; antennal notch deep, triangular; antero-lateral angle pointed, lower margin of carapace with 16–17 teeth. Pereon 0.85–0.92 times carapace length. Pleon 0.52–0.53 times total body length, without ridges; pleonite 6 1.4–1.5 times as long as wide, projecting posteriorly between uropods.

Antenna 1 ( Fig. 6E View FIGURE 6 ) peduncle article 1 near straight, 1.7–1.9 times as long as article 2, 1.2–1.3 times as long as article 3, with two spines on distal region; article 2 with four small spines and 1–2 feather-like setae; article 3 1.4–1.5 times as long as article 2, with 1–2 feather-like setae on lateral margin. Main flagellum biarticulate, very thick, as wide as distal end of peduncle article 3, 0.3 times as long as peduncle article 3; article 2 with four hard curved setae, two directed laterally (arrowheads in Fig. 6E View FIGURE 6 ); button-like accessory flagellum minute.Antenna 2 ( Fig. 6F View FIGURE 6 ) biarticulate, basal article with three long pappose setae near inferior margin. Left and right mandibles ( Fig. 6G View FIGURE 6 ) navicular, with 15 setae on inner margin, respectively; lacinia mobilis tridentate; incisor process tridentate. Labium ( Fig. 6H View FIGURE 6 ) distal end narrow, with five broad setae. Maxilla 1 ( Fig. 7A View FIGURE 7 ) outer endite broad, with 12 simple or dentate spiniform setae arranged near linearly; inner endite rather narrow distally, with one tridentate and three simple setae; palp with two terminal setae. Maxilla 2 ( Fig. 7B, C View FIGURE 7 ) narrow endites with 30 and 27 setae, respectively; broad endite distal margin with 27 setae of various shape on upper margin, 28 thin (broad at base) setae on lower margin. Maxilliped 1 ( Fig. 7D, E View FIGURE 7 ) with 16 branchial lobules; carpus with 13 simple setae on ventral surface and eight non-dentate robust setae on inner margin; propodus rather thin, curved, with two setulate setae; dactylus weakly curved, with three short, spiniform setae with setules. Maxilliped 2 ( Fig. 7F View FIGURE 7 ) basis 0.7 times as long as distal articles together, with long plumose seta in inner distal corner; carpus with 9–11 setae on inner margin; propodus with 3–7 setae on inner margin; dactylus with three terminal and two subterminal setae; rudimentary oostegite of coxa with 7–8 setae in ovigerous female. Maxilliped 3 ( Fig. 8A View FIGURE 8 ) basis 0.8–0.9 times as long as distal articles together, with two spines and plumose seta on inner distal corner; outer distal corner projected reaching mid region of carpus, with 3–5 plumose setae on inner margin and two long plumose terminal setae; ischium with 2–4 plumose setae on inner margin; merus greatly expanded, exceeding distal end of carpus, with 1–3 plumose setae on inner margin and 10–11 setae on outer margin; ventral surface of merus, ischium and carpus forming flat area with scale-like sculpture; propodus 1.6–1.9 times as long as carpus and 2.0–2.2 times as long as dactylus, with 3–4 simple setae on inner margin; dactylus with three terminal setae; well-developed exopod flagellum of five articles.

Pereopod 1 ( Fig. 8B View FIGURE 8 ) basis 0.5–0.6 times as long as distal articles together, with 0–1 plumose setae on inner distal corner; inner and outer margin serrated; ischium and merus with plumose seta on inner distal corner; carpus thick, 2.1–2.6 times as long as merus, 1.5–1.6 times as long as propodus, with pappose seta on inner margin and 4–5 short feather-like setae on outer margin; propodus curved near proximal end, 1.1–1.3 times as long as dactylus, with two robust setae on distal end; dactylus with 6–8 stiff, denticulate setae directing outward and forward; well-developed exopod flagellum of six articles.

Pereopod 2 ( Fig. 8C View FIGURE 8 ) basis 0.5 times as long as remaining articles together, with 5–6 simple setae on distal corner; merus and carpus short, with two and three robust setae, respectively; propodus triangular, inner region not visible; dactylus 1.4–1.6 times as long as basis, with 3three rows of 3–4 robust denticulate setae.

Pereopod 3 ( Fig. 8D View FIGURE 8 ) basis 0.8–1.0 times as long as distal articles together, with 3–4 pappose and 2–3 setulate setae on lateral margin, 1–2 plumose setae on distal corner; ischium with 5–6 simple setae on distal corner: merus with two simple setae on distal corner; carpus with 4–5 simple setae on distal corner; dactylus much longer than wide, with robust terminal seta having two rows of denticles.

Pereopod 4 ( Fig. 8E View FIGURE 8 ) basis 0.5 times as long as distal articles together, with four pappose or simple setae on lateral margin, 1–2 simple setae on distal corner; ischium with 4–6 simple setae on distal corner; carpus with 4–5 simple setae on distal region, dactylus much longer than wide, robust terminal seta with two rows of denticles.

Pereonite 5 ( Fig. 8F View FIGURE 8 ) basis 0.3–0.5 times as long as distal articles together, with 0–1 pappose seta on lateral margin, two simple or pappose setae on distal corner; ischium with five simple setae on distal end; merus with two simple setae; carpus with five simple setae on distal region; dactylus much longer than wide, robust terminal seta with two rows of denticles. Uropod ( Fig. 8G View FIGURE 8 ) peduncle 1.0–1.1 times pleonite 6 length, 1.2–1.5 times as long as exopod, 0.9–1.0 times as long as endopod, with 5–6 spiniform setae; exopod 0.7 times as long as endopod, with 4–8 spiniform setae on outer margin, five robust setae on apex; endopod biarticulate, article 1 1.7–1.9 times as long as article 2, with 6–7 spiniform setae on inner margin; article 2 with 2–3 spiniform setae on inner margin and two terminal setae.

Paratype 1 juvenile female, 4.2 mm. The specimen is very similar to the ovigerous and preparatory females. Dorsal region of pereonite 1 narrow, visible on dorsal region .

Etymology. The species’ name refers to the type locality, the Sulu Sea.

Remarks. The new species is closely similar to Iphinoe crassipes Hansen, 1895 from the west coast of Africa and the Mediterranean, 6– 103m. The adult specimens were well described in Stebbing (1910), Băcescu (1961), Day, (1978), Petrescu (1998), and Corbera (1994). Iphinoe suluensis sp. nov. is distinguished from I. crassipes by (1) having 4–8 spiniform setae present on the outer margin of the uropod exopod (not present in I. crassipes ), (2) the median-dorsal ridge of the carapace obsolete (discernible, with small teeth in I. crassipes ), (3) the antenna 1 main flagellum article 2 with 4 stiff simple setae (1–2 simple setae in I. crassipes ).

Iphinoe suluensis is also similar to Iphinoe pokoui Le Loeuff & Intes, 1972 from Cote D’Ivoire, western coast of Africa, 20 m. The former species is distinguished from the latter by (1) the carapace has longitudinal ridges for the entire length (anterior portion in I. pokoui ), (2) the antennal notch is triangular (round, widely open in I. pokoui ), (3) the uropod endopod is longer than the exopod (subequal or slightly shorter than exopod in I. pokoui ), and (4) the uropod exopod article 2 is much longer than article 1 (subequal in length to article 1 in I. pokoui ).