Podocerus cf. danae ( Stebbing, 1888 )

Coleman, Charles Oliver, Krapp-Schickel, Traudl & Häussermann, Vreni, 2022, Amphipod crustaceans from Chilean Patagonia, European Journal of Taxonomy 849 (1), pp. 1-57 : 38-39

Podocerus cf. danae ( Stebbing, 1888)

Fig. 30e–f

Platophium danae Stebbing, 1888: 1185 , pls 128–129.

Platophium orientale Della Valle, 1893: 332 (in part).

Podocerus danae armatus Bellan-Santini & Ledoyer, 1987: 418–421 .

Podocerus danae – Stebbing 1899: 239; 1906: 705, fig. 122. — Chilton 1926: 514. — J.L. Barnard 1958: 122; 1962: 65 (in key). — Mills 1972: 75, table 1. — Lowry & Bullock 1976: 132. — BellanSantini & Ledoyer 1987: 418–419, fig. 25. — J.L. Barnard & Karaman 1991: 665. — Branch et al. 1991: 16, 39–40, fig. on p. 16. — De Broyer & Jażdżewski 1993: 88.

Material examined

CHILE • 1 ♂ (7 mm); Canal Williams – Southern Exit ; -45.601028°, -74.478194°; 15 m depth; 19 Nov. 2011; HF11C004; on hydrozoans, together with pycnogonids; colour brownish; ZMB 34210 • 1 juv. (4 mm); same collection data as for preceding ; 20.5 m depth; HF11C006; ZMB 34209 • 1 ovigerous ♀ (6 mm); same collection data as for preceding ; 8.9 m depth; HF11C012; on hydrozoans; colour brownish; ZMB 34208 .

Description (based on ♂, 7 mm)

HEAD. Without rostrum, lateral cephalic lobes angled; in the middle of the back of the head a rounded small process (vs P. danae , like P. danae armatus ).

BODY. Each of the pereonites 1–4 with moderate elevation posterodorsally (vs P. danae , like P. danae armatus ), the size depending on age; on pereon segment 4 dorsally with 2 long setae (vs P. danae , like P. danae armatus ). Only pereonites 5–7 and first pleon segment with one large triangular process each (according to the original description of P. danae , vs P. danae armatus ). No lateral additional teeth on pereonite 7 (vs P. danae ). Pleon strongly flexed. Body cuticule without hair-like setae (vs P. danae , like P. danae armatus ). Eyes very prominent, projecting, round.

HEAD APPENDAGES. Antenna 1 peduncle article 1 robust, length subequal to head; peduncle article 2 narrower and up to twice as long as article 1; article 3 subequal to article 2; flagellum with 9 articles; accessory flagellum with one long and one very small article (not described in P. danae and P. danae armatus ). Antenna 2 much longer than antenna 1; peduncle article 3 quadrangular, distally somewhat expanded; article 4 reaching beyond peduncle of antenna 1, 2× as wide as last peduncle articles of antenna 1, 3–4 × as long as article 3; article 5 somewhat less wide, but much longer than article 4; all peduncle articles beset with short setae on both margins; flagellum with 4 articles (last one very reduced), combined about same length as article 4 of peduncle.

PEREON. Gnathopod 1 coxa much longer than wide; basis slender; ischium somewhat longer than wide, quadrangular; merus with prominent angle of about 90° on posterior margin (vs P. danae , like P. danae armatus ); carpus somewhat box-shaped with rectangular posterior margin, the distal corner of about 120° and the proximal a right angle; propodus of triangular shape with palmar corner also of 90°; dactylus strongly curved, on inner side densely spinose. The entire leg densely setose on posterior margin, much less on anterior one. Gnathopod 2 much larger than gnathopod 1; coxa longer than wide, much shorter than propodus; basis long and strong, distally only scarcely expanded (in Stebbing 1888 not widened at all, in Bellan-Santini & Ledoyer 1987 for P. danae armatus with prominent corner); merus rectangular, shorter than wide; carpus with acute gently curved tooth posterodistally, longer than wide; propodus about twice as long as head and 5–6 × as long as propodus of gnathopod 1; anterior margin regularly convex with 4 groups of setae on distal half; posterior margin remarkably straight, palm nearly covering all the posterior margin, only on the most proximal tenth part of propodus slightly narrowing, forming a blunt palmar corner; along distal quarter of the margin three blunt triangular humps, hidden under very long and dense ciliated setae all over the palm; dactylus slender and straight, about length of palm; inner margin smooth. Pereopod 3 merus, carpus and propodus subequal, dactylus half length of propodus. Pereopod 4 similar, but merus a bit shorter. Pereopods 5–7 merus distally widened but not lengthened, propodus and carpus more robust than in the preceding legs; dactylus strong, longer than half propodus.

UROSOME. Uropod 1 peduncle about as long as inner ramus; outer ramus shorter; peduncular spur about one third of length of outer ramus. Uropod 2 smaller than uropod 1, peduncle much shorter. Telson scarcely shorter than broad (like P. danae ) or scarcely longer than broad (like P. danae armatus ), with rounded distal corners.

Distribution

Podocerus danae: Kerguelen , 230 m depth ( Stebbing 1888); P. danae armatus: Marion and Prince Edward islands ( Bellan-Santini & Ledoyer 1987, 110– 570 m depth, together with P. danae ). Canal Williams, Chile, this study.

Depth range

8.9– 570 m.

Type locality

Kerguelen Islands: Challenger 1873–76, stn 149H, off Baie de Recques (Cumberland Bay), -48.75°, 69.233333°, 232 m ( Stebbing 1888).

Type specimen location

The Natural History Museum, London.

Remarks

Bellan-Santini & Ledoyer (1987) found Podocerus danae together with their new subspecies Podocerus danae armatus (!), and they repeated that several characters of these specimens are not clearly defined, but vary with age. In our collection there are only two adult specimens and one juvenile found, thus it is not possible to add statistically informative data about the limits of variations.

Figures

Fig. 30. In vivo photos of some of the described amphipods. a. Sunamphitoe femorata (Krøyer, 1845). b. Numerous specimensof Caprellacf.equilibraSay, 1818,on thehydrozoanHalopteris schucherti Galea, 2006. c. Habitat of Leucothoe kawesqari Esquete & Aldea, 2015, on sponge. d. Epimeria (Metepimeria) acanthurus (Schellenberg, 1931). e–f. Podocerus cf. danae (Stebbing, 1888). g. Liouvillea rocagloria sp. nov. h. Habitat of Liouvillea rocagloria sp. nov. Photos: Iván Hinojosa (a); V. Häussermann & G. Försterra (b, d, h); G. Försterra & V. Häussermann (c, e–g).