Capropodocerus kamaitachi, Matsumoto & Kajihara & Kakui, 2023

Matsumoto, Yu, Kajihara, Hiroshi & Kakui, Keiichi, 2023, Capropodocerus, a new genus in Podoceridae (Crustacea: Amphipoda) from Japan, with descriptions of two new species, Zootaxa 5336 (4), pp. 577-589 : 583-587

publication ID	https://doi.org/ 10.11646/zootaxa.5336.4.8
publication LSID	lsid:zoobank.org:pub:B87600AF-C095-4361-9692-5E3B5B6A8E78
DOI	https://doi.org/10.5281/zenodo.8282551
persistent identifier	https://treatment.plazi.org/id/038F87AA-FF9C-7A19-FF51-F921FCF7FF12
treatment provided by	Plazi
scientific name	Capropodocerus kamaitachi
status	sp. nov.

Treatment

Capropodocerus kamaitachi sp. nov.

[New Japanese name: Oogama-warekara-doronomi]

Figs 1B View FIGURE 1 , 5 View FIGURE 5 , 6 View FIGURE 6

Diagnosis. Length ratio of antenna 1 peduncle to flagellum 1.45. Gnathopod 2 palm with straight margin bearing one distal, one subdistal, and one proximal large triangular projections. Mid-posterior triangular projection present on gnathopod 2 dactylus. Length ratio of basis to merus of pereopod 3 2.50.

Etymology. This species evokes the image of Kama-itachi (“sickle weasels”), mythical Japanese ghosts that look like a weasel and bear a sickle.

Type material. Holotype. Male (?), ICHUM6355 View Materials , R / V Soyo-maru, Stn. Kago-8, off Miyagi, Japan, northwestern Pacific (37°26.65′ N 142°18.10′ E to 37°27.55′ N 132°18.78′ E), 840–873 m, small plankton net attached inside larger beam trawl; collected 2 August 2012 by Shinri Tomioka and Keiichi Kakui. GoogleMaps

Description. Body ( Figs 1B View FIGURE 1 , 5A, B View FIGURE 5 ) 5.40 mm long. Head 0.58 mm long; eye distinct. Pereonites 1–7 0.82 mm, 0.85 mm, 0.89 mm, 0.29 mm, 0.24 mm, 0.19 mm, 0.31 mm long, respectively. Pereonites 1–3 cylindrical; pereonite 1 longer than wide, without lateral suture; pereonite 2 as long as wide, spherical in dorsal view; pereonite 3 longer than wide, suture visible laterally. Pereonites 4–7 similar, depressed, wider than long. Pleonites 1–3 similar. Urosome with 3 segments.

Antenna 1 ( Fig. 5C, C View FIGURE 5 1 View FIGURE 1 ) 3.88 mm long, longer than antenna 2. Peduncle with three articles, 2.30 mm long (articles 1–3 0.35 mm, 1.03 mm, and 0.92 mm long, respectively); all articles with dorsal simple setae and ventral setulate setae; article 1 with two dorso-subproximal plumose setae. Accessory flagellum ( Fig. 5C View FIGURE 5 1 View FIGURE 1 ) small, as long as wide, with three distal simple setae. Flagellum with three articles, 1.58 mm long (articles 1–3 0.76 mm, 0.48 mm, 0.34 mm long, respectively); articles 1 and 2 each with several dorsal simple setae and several ventral setulate setae; article 3 with three simple setae and distal plumose seta.

Antenna 2 ( Fig. 5D, D View FIGURE 5 1 View FIGURE 1 ) 3.03 mm long. Peduncle with five articles (articles 1 and 2 fused), 2.10 mm long; articles 1 and 2 with evident antennal gland cone directed ventrodistally; article 3 with ventral setulate setae and two ventral plumose setae; articles 4 and 5 with dorsal simple setae, ventral setulate setae; article 5 with one ventral plumose seta. Flagellum with three articles, 0.93 mm long; article 1 with dorsal simple setae and ventral setulate setae; article 2 with three dorsal, one dorsodistal, and one ventrodistal simple setae and two ventrodistal thick, bifurcate setae; article 3 ( Fig. 5D View FIGURE 5 1 View FIGURE 1 ) tiny, with three distal simple setae.

Upper lip lost. Mandibles ( Fig. 5E, E View FIGURE 5 1, F, F1 View FIGURE 1 ) with incisor with four (left) or five (right) cusps; lacinia mobilis with four (left) or two (right) cusps; subdistal region with three (left) or two (right) accessory blades and two (left) or one (right) plumose setae; molar with plate-like structure bearing pectinate margin. Palp with article 1 lacking setae; article 2 with medial setulate setae; article 3 distally expanded, with setulate setae in distal half. Lower lip ( Fig. 5G View FIGURE 5 ) with well-developed inner lobes; distal regions of inner and outer lobes covered with fine setae. Maxilla 1 ( Fig. 5H View FIGURE 5 ) with vestigial inner plate bearing distal fine setae; outer plate with eight distal robust setae (six bifurcate, two serrate). Palp with article 1 lacking setae; article 2 with five distal robust serrate setae (two bifurcate, three serrate) and three subdistal setulate setae. Maxilla 2 ( Fig. 5I View FIGURE 5 ) with inner and outer plates having distal robust serrate setae. Maxillipeds ( Fig. 6A, A View FIGURE 6 1 View FIGURE 1 , 2 View FIGURE 2 ) with inner plate bearing three short robust setae and several setulate setae; outer plate with three ventral setulate setae and four medial and three distal robust setae (one bifurcate, one bifurcate, three simple, one broken). Palp with four articles: article 1 without setae; article 2 with medial row of setulate setae; article 3 with distal setulate setae; article 4 distally serrated, with lateral setulate seta in proximal region and two simple, one serrate, and one robust and serrate setae in medio-distal region.

Gnathopod 1 ( Fig. 6B View FIGURE 6 ) transverse, 1.35 mm long; basis, ischium, merus, carpus, propodus, dactylus 0.30 mm, 0.12 mm, 0.07 mm, 0.32 mm, 0.34 mm, 0.20 mm long, respectively. Coxa without lateral projection but with simple seta. Basis with two simple setae. Ischium with two simple and one setulate setae in posterodistal region. Merus with posterodistal expansion, one mediodistal and four posterodistal simple setae, and one mediodistal and three posterodistal setulate setae. Carpus with posterolateral shield-like expansion, two medial and 18 posterior simple setae, and two posterodistal and three medial setulate setae. Propodus expanded distally, 1.25 times longer than wide, with posterior row of simple setae, two anterior medio-subproximal, two anterior, three anterodistal, one medial, and two lateral simple setae, and two anterior medio-subdistal setulate setae; palmar margin slightly convex, smooth, with row of simple setae and two posterolateral and one posteromedial robust setae. Dactylus slightly curved posteriorly with several anterior fine setae and posterior row of simple setae.

Gnathopod 2 ( Fig. 6C View FIGURE 6 ) subchelate, 5.41 mm long; basis, ischium, merus, carpus, propodus, dactylus 1.53 mm, 0.34 mm, 0.26 mm, 0.43 mm, 1.65 mm, 1.12 mm long, respectively. Coxa not laterally projecting. Basis with anterosubproximal hump and anterodistal expansion. Ischium and merus without setae. Carpus expanded distally, with two posterodistal simple setae. Propodus expanded distally, 1.60 times as long as wide, with several anterior fine setae and two lateral simple setae; palmar margin straight, with several simple setae and one distal, one subdistal, and one proximal large triangular projections. Dactylus curved posteriorly, several tiny fine setae and mid-posterior triangular projection.

Pereopod 3 ( Fig. 6D View FIGURE 6 ) 1.88 mm long, with length ratio of basis, ischium, merus, carpus, propodus, and dactylus 1.00:0.16:0.40:0.47:0.55:0.43. Coxa weakly pointed laterally. Merus with two anterior simple setae. Carpus with one anterodistal simple seta. Propodus with two mid-anterior, two anteriodistal, and three posterior simple setae and distal plumose seta. Dactylus with two anterior simple setae. Pereopods 4–7 ( Fig. 6E–H View FIGURE 6 ) similar to pereopod 3, 1.83 mm, 1.94 mm, 2.01 mm, and 2.07 mm long, respectively; length ratio of basis, ischium, merus, carpus, propodus, and dactylus 1.00:0.28:0.59:0.62:0.82: 0.66 in pereopod 4, 1.00:0.29:0.67:0.80:1.15: 0.93 in pereopod 5, 1.00:0.32:0.62:0.75:1.22: 0.84 in pereopod 6, and 1.00:0.33:0.71:0.60:1.27: 0.91 in pereopod 7.

Pleopods 3 pairs ( Fig. 1B View FIGURE 1 ); lost during dissection.

Uropod 1 ( Fig. 5B View FIGURE 5 ) biramous. Peduncle without setae. Inner and outer rami each with terminal robust seta. Uropod 3 ( Fig. 5B View FIGURE 5 ) uniramous, uniarticulate, without setae.

Telson ( Fig. 5B View FIGURE 5 ) entire, linguiform, with paired simple setae.