Capropodocerus kamaitachi Matsumoto & Kajihara & Kakui 2023, sp. nov.
Creators: name: Matsumoto, Yu
name: Kajihara, Hiroshi
name: Kakui, Keiichi
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Podoceridae
Capropodocerus
Capropodocerus kamaitachi

description: Capropodocerus kamaitachi sp. nov.
[New Japanese name: Oogama-warekara-doronomi]
Figs 1B, 5, 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, 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.
Description. Body (Figs 1B, 5A, B) 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 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 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 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 1) tiny, with three distal simple setae.
Upper lip lost. Mandibles (Fig. 5E, E 1, F, F1) 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) with well-developed inner lobes; distal regions of inner and outer lobes covered with fine setae. Maxilla 1 (Fig. 5H) 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) with inner and outer plates having distal robust serrate setae. Maxillipeds (Fig. 6A, A 1, 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) 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) 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) 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) 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); lost during dissection.
Uropod 1 (Fig. 5B) biramous. Peduncle without setae. Inner and outer rami each with terminal robust seta. Uropod 3 (Fig. 5B) uniramous, uniarticulate, without setae.
Telson (Fig. 5B) entire, linguiform, with paired simple setae.
description: Published as part of Matsumoto, Yu, Kajihara, Hiroshi & Kakui, Keiichi, 2023, Capropodocerus, a new genus in Podoceridae (Crustacea: Amphipoda) from Japan, with descriptions of two new species, pp. 577-589 in Zootaxa 5336 (4) on pages 583-587, DOI: 10.11646/zootaxa.5336.4.8, http://zenodo.org/record/8282294