Campylaspenis sigeogamoi, Akiyama, 2025

Akiyama, Tadashi, 2025, On some species of the genera Campylaspenis and Campylaspis (Crustacea, Cumacea, Nannastacidae) from the Sea of Japan (Northwest Pacific), with description of a new species of Campylaspenis, Zootaxa 5665 (4), pp. 543-562 : 544-548

publication ID	https://doi.org/10.11646/zootaxa.5665.4.3
publication LSID	lsid:zoobank.org:pub:99EC4A73-E1CC-4D3B-85B8-1840B0E34602
persistent identifier	https://treatment.plazi.org/id/03C1879B-FFDB-FFDD-D0DB-FCD2AA1C7239
treatment provided by	Plazi
scientific name	Campylaspenis sigeogamoi
status	sp. nov.

Treatment

Campylaspenis sigeogamoi sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Campylaspis sp. 2 Akiyama, 2014: 168.

Diagnosis. Females: Carapace with three weak oblique ridges on each side, vertical ridge connecting1st and 2nd oblique ridge obsolete; 1st oblique ridge branch and re-unite on dorsal surface, making encircled region; pseudorostrum 0.11–0.13 times carapace length, not upturned; eye lobe semicircular; frontal lobe with no 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 2.1–2.5 times pleonite 6, 2.1–2.3 times exopod and 1.9–2.2 times endopod; exopod 0.9 times endopod. Males. Pereonite 5 with pair of large penial lobes; pleon with lateral groove; antenna 2 exceeding posterior end of pleon; uropod peduncle 2.4–2.7 times pleonite 6, 2.3–2.4 times exopod and 1.9–2.0 times endopod.

Material examined. Holotype ovigerous female, 3.3 mm ( NSMT Cr-32968), off Esashi , northern coast of Hokkaido, the Sea of Japan, 41°47.46΄N, 139°34.49΄E–41° 48.96΄N, 139° 34.88΄E, 563–605 m (KT-11-9, St. E 3), 29 May 2011 . Paratypes. 52 females, 22 males, 11 juveniles (including dissected 5 ovigerous females, 3.0– 3.4 mm, 3 adult males, 3.8–3.9 mm ( NSMT Cr-22792), same locality and date as holotype female (KT-11-9, St. E 3).

Description. Holotype ovigerous female, 3.3 mm ( Figs. 1A, B View FIGURE 1 ). Carapace 0.44 times total body length, 1.37 times width and 1.75 times depth, with short setae; integument with scale-like sculpture, making numerous minute spines directing outward on carapace; each side with 3 weak oblique ridges running parallel, 1st oblique ridge branch and re-unite on dorsal surface, making encircled region; short vertical ridge connecting 1st and 2nd oblique ridges absent; third oblique ridge and posterior end of carapace a little apart; pseudorostrum 0.13 times carapace width, not upturned; width of semicircular eye lobe 0.12 times carapace width, 1.19 times eye lobe length; frontal lobe without transverse ridge ( Fig. 1B View FIGURE 1 ); antennal notch obsolete; lower margin with very small teeth. Pereon ( Fig. 1A View FIGURE 1 ) 0.40 times carapace length. Pleon ( Fig. 1A View FIGURE 1 ) 0.38 times total body length, with weak lateral ridge on each side.

Paratype ovigerous females, 3.0– 3.4 mm. Carapace 0.43–0.45 times total body length, 1.34–1.41 times width and 1.41–1.83 times depth; integument covered with scale-like sculpture, forming minute spine anteriorly ( Fig. 1C View FIGURE 1 ); very weak vertical ridge connecting 1st and 2nd oblique ridges present or absent; frontal lobe without transverse ridge; width of semicircular eye lobe 0.09–0.12 times carapace width, 1.0–1.2 times eye lobe length; pseudorostrum 0.11–0.13 times carapace width, not upturned; antennal notch obsolete; lower margin with minute teeth or spines (anterior end of scale-like sculpture). Pereon 0.37–0.44 times carapace length. Pleon 0.37–0.38 times total body length. pleonite 6 ( Fig. 2G View FIGURE 2 ) length 0.66–0.79 times as long as wide.

Antenna 1 ( Fig. 1D View FIGURE 1 ), peduncle basal article curved, 1.0–1.4 times articles 2 and 1.1–1.4 times article 3, with simple seta on distal corner; article 2 with 1 short simple seta on distal region; article 3 0.9–1.0 times article 2. Main flagellum 3-articulate, 0.8–0.9 times peduncle article 3; basal article 0.9–1.1 times combined length of articles 2 and 3; accessory flagellum uni-articulate, 0.4–0.5 times article 1 of main flagellum. Antenna 2 ( Fig. 1E View FIGURE 1 ) uni-articulate without setae, with 4–7 tubercles on distal region. Left and right mandibles ( Fig. 1F View FIGURE 1 ) with 3 and 4 robust setae with many minute tubercles, respectively; molar process styliform, 4- or 5- dentate; lacinia mobilis 4- dentate; incisor process 5- or 6- dentate. Maxilla 1 ( Fig. 1G View FIGURE 1 ) outer endite with 9–10 robust setae, some of which dentate; lower 2 setae a little apart from the remaining setae; narrow endite with 5 ciliated setae; palp with 1 terminal seta. Distal end of maxilla 2 ( Fig. 1H View FIGURE 1 ) narrow, with 3 terminal and 1 subterminal setae. Maxilliped 1 ( Fig. 1I View FIGURE 1 ) with 11–12 branchial lobules; merocarpus with 3–4 simple setae on distal region and 3–5 short simple setae on inner margin; dactylus minute, 0.043 –0.052 times merocarpus length. Maxilliped 2 ( Fig. 1J View FIGURE 1 ) basis 0.6–0.7 times combined length of distal articles together, with simple seta on inner distal corner; ischium naked; merus with 0–1 plumose setae on inner margin; carpus with 2–3 denticules, 1–2 simple and 0–1 plumose setae on inner margin; propodus rather elongate, with 1 long terminal spine; joint between carpus and propodus strongly bend; dactylus with 3 long terminal spine; coxa with 8–10 setae. Maxilliped 3 ( Fig. 2A View FIGURE 2 ) basis 0.7 times distal articles together; inner distal corner projected, with 2–4 spines, 2 plumose and 0–1 simple setae; outer distal corner with 2 plumose setae; ischium short; merus 1.0–1.1 times combined length of carpus and propodus, with 8–9 teeth and 6–7 short simple setae on inner margin and 3–5 teeth and 1 plumose seta on outer margin; carpus with 3–5 teeth and 3–5 simple setae on inner margin, 3 teeth and plumose seta on outer margin; propodus with 4–5 teeth and 3 plumose setae on inner margin, plumose seta on outer distal corner; dactylus with 3–4 terminal setae; exopod flagellum of 3 articles.

Pereopod 1 ( Fig. 2B View FIGURE 2 ) basis 0.8 times distal articles together, with 3 plumose setae on inner margin and 1 plumose seta on outer distal corner; merus 0.7–0.8 times combined length of carpus and propodus, with 1–3 plumose and 4–5 simple setae on inner margin, 4–6 teeth and 2 plumose setae on outer margin; carpus with 4–5 teeth and 3–4 simple setae on inner margin, 2–5 teeth and 2 plumose setae on outer margin; propodus with 2–3 teeth and 2 simple seta on inner margin, 3 plumose setae on outer margin; dactylus with 5–6 simple setae; exopod flagellum of 4 articles. Pereopod 2 ( Fig. 2C View FIGURE 2 ) basis 0.5 times distal articles together, with 2 plumose seta on inner margin and 1 plumose seta on outer distal corner; carpus with 0–2 plumose and 0–2 simple setae on lateral margin; dactylus 1.6–1.9 times carpus, with 9–12 setae; exopod flagellum of 4 articles. Pereopod 3 ( Fig. 2D View FIGURE 2 ) basis 1.1–1.4 times distal articles together, with two rows of plumose and simple setae on lateral margin. Pereopod 4 ( Fig. 2E View FIGURE 2 ) basis 0.9–1.0 times distal articles together, with plumose seta on distal corner and plumose seta on side. Pereopod 5 ( Fig. 2F View FIGURE 2 ) basis 0.5–0.6 times distal articles together. Terminal setae on dactylus of pereopods 3–5 fused to the articles.

Uropod ( Fig. 2G View FIGURE 2 ) peduncle 2.1–2.5 times pleonite 6 length, 2.1–2.3 times exopod, 1.9–2.2 times endopod, serrated on inner and outer margin, exopod 0.9 times endopod, with 2 terminal seta; endopod uni-articulate, with 4–5 spiniform setae on inner margin and terminal seta.

Paratype 3 adult males, 3.8–3.9 mm ( Fig. 3 View FIGURE 3 ). Carapace ( Fig. 3A, B View FIGURE 3 ) 0.39–0.41 times total body length, 1.39– 1.44 times width, 1.93–2.17 times depth, covered with short setae; each side with 3 oblique ridges running parallel; pseudorostrum ( Fig. 3A, B View FIGURE 3 ) 0.092 –0.099 times carapace length, not upturned; width of eye lobe 0.10–0.12 times carapace width, 1.1–1.4 times eye lobe length; corneal lenses absent; frontal lobe without transverse ridge; antennal notch shallow. Pereon ( Fig. 3A View FIGURE 3 ) 0.52–0.60 times carapace length; posterior margin of lateral projection on pereonite

3–5 round; pereonite 5 with a pair of penial lobe ( Fig. 3C, D View FIGURE 3 ); penial lobe longer than basis of pereopod 5. Pleon ( Fig. 3A View FIGURE 3 ) 0.37–0.39 times total body length, with lateral grooves; pleonite 6 0.9 times as long as wide.

Antenna 1 ( Fig. 3E View FIGURE 3 ), peduncle basal article 1.2–1.3 times article 2 and 1.5–1.6 times article 3; article 3 0.8 times article 2; Main flagellum tri-articulate, 1.0 times peduncle article 3; articles 2 and 3 with 1 aesthetasc, respectively; accessory flagellum uni-articulate, 0.4–0.5 times main flagellum article 1. Antenna 2 ( Fig. 3F View FIGURE 3 ) peduncle article 5 2.3– 2.6 times article 4; flagellum of 20 articles, exceeding posterior end of pleon. Maxilliped 3 ( Fig. 3G View FIGURE 3 ) basis 0.7– 0.8 times distal articles together, with 2 plumose setae on inner distal corner and 1–3 plumose setae on outer distal corner; merus 0.8–0.9 times combined length of carpus and dactylus, with 7–8 teeth and 7–9 short simple setae on inner margin, 4–7 teeth and plumose seta on outer margin; carpus with 3 teeth and 1 plumose, 3–4 simple setae on inner margin, 3 teeth and plumose seta on outer margin; propodus with 4–5 teeth and 3 plumose setae on inner margin and plumose seta on outer distal corner; dactylus with 4–5 terminal setae; exopod flagellum of 6 articles.

Pereopod 1 ( Fig. 3H View FIGURE 3 ), basis 0.8–0.9 times distal articles together, inner distal corner projected, with 1–2 plumose setae; outer distal corner with 1–2 plumose setae; merus 0.7 times combined length of carpus and propodus, with 1–2 plumose and 3–4 simple setae on inner margin and 2–4 teeth and 2 plumose setae on outer margin; carpus with 3–4 teeth and 3 simple setae on inner margin, 2 teeth and 2 plumose setae on outer margin; propodus with 2–3 teeth and 1–2 simple setae on inner margin, 3 plumose setae on outer margin; exopod flagellum of 6-articles. Pereopod 2 ( Fig. 3I View FIGURE 3 ) basis 0.6–0.7 times distal articles together, with plumose seta on inner and outer distal corner; merus with 1 plumose and 0–1 simple setae on outer margin and 1 plumose and 0–1 simple setae on inner distal corner; carpus with 2 plumose and 1–3simple setae on outer margin; dactylus 1.6–1.9 times carpus, with 11–13 setae; exopod flagellum of 6 articles. Pereopod 3 ( Fig. 3J View FIGURE 3 ) basis 1.6 times distal articles together, with 2–3 plumose setae on inner margin and plumose seta on outer margin; exopod flagellum of 6 articles. Pereopod 4 ( Fig. 3K View FIGURE 3 ) basis 1.1–1.2 times distal articles together, with plumose seta on inner distal corner, exopod flagellum 6-articulate. Pereopod 5 ( Fig. 3L View FIGURE 3 ) basis 0.6–0.7 times distal articles together, with plumose seta on distal corner and lateral margin, respectively.

Uropod ( Fig. 3M View FIGURE 3 ) peduncle 2.4–2.7 times pleonite 6, 2.3–2.4 times exopod and 1.9–2.0 times endopod, with 7–9 plumose and 0–1 simple setae on inner margin; exopod 0.8 times endopod, with long simple terminal seta and plumose subterminal seta, outer margin with 1–2 simple setae; endopod uni-articulate, with 9–12 spiniform setae on inner margin and robust terminal seta.

Etymology. The species name is dedicated to Dr. Sigeo Gamô, who made great contributions to cumacean taxonomy.

Remarks. Male specimens of the present new species are similar to C. rowei Bacescu and Muradian, 1974 from south of Cape Hatteras, North Carolina, western Atlantic, 3045 m. The new species is distinguished from C. rowei by (1) posterior margin of lateral projection on pereonite 3–5 round (pointed in C. rowei ), (2) separated region of left and right penial lobes subequal in length to the proximal, unseparated region of the lobes (shorter in C. rowei ), spermatozoa not observable on tip (observable in C. rowei ) (3) eye lobe width 0.10–0.12 times carapace width (0.09 in C. rowei ), (4) uropod peduncle slightly shorter than combined length of last 3 pleonites (longer than combined length of last 3 pleonites in C. rowei ).

Distribution. Japanese coast of the Sea of Japan, 563– 605 m.