Chauliopleona amdrupii ( Hansen 1913 )

Bird, Graham John, 2015, Tanaidacea (Crustacea: Peracarida) of the northeast Atlantic: Chauliopleona Dojiri and Sieg, 1997 and Saurotipleona n. gen. from the ‘ Atlantic Margin’, Journal of Natural History (J. Nat. Hist.) 49, pp. 1-41 : 9-13

Chauliopleona amdrupii ( Hansen 1913)

( Figures 2–4 , 18 )

Leptognathia Amdrupii Hansen, 1913: 81–82 , pl. VIII figs. 2a–c

Leptognathia amdrupi: Nierstrasz 1913: 30 ; Stephensen 1932: 347; Stephensen 1937: 23; Stephensen 1943: 36, 63; Just 1970: 24; else, see Sieg 1983

Chauliopleona amdrupii: Guerrero-Kommritz 2005: 1184–1187 , figs 3–4; else, see Anderson 2013

Diagnosis

Cephalothorax 1.4 times longer than broad (ltb). Pereonites 1–6 all shorter than broad, with parallel lateral margins. Pleon shorter than cephalothorax, without posteriodorsal protuberances; pleonites 1–4 sternite with low recurved subrectangular process. Antennule article-1 (1.25 times) longer than rest of antennule. Maxilliped bases with short distal seta. Cheliped merus without inferior protuberance; carpus relatively slender, twice as long as broad, inferior shield shallow (aspect ratio ≈ 0.2), subtriangular, distal margin not angular; fixed finger with four teeth; dactylus superior margin smooth. Pereopods 1–3 basis with marginal setules; carpus and propodus inferior spinules fine to moderate; pereopods 2–3 carpus with distomedial seta. Pereopods 4–6 ischium with two short setae. Uropod exopod just over half the length of endopod segment-1; endopod slender,> three times longer than peduncle.

Material examined

One non-ov. ♀, BIOICE Stn 2257; one non-ov. ♀, BIOICE Stn 2697; one non-ov. ♀, BIOICE Stn 2701; two non-ov. ♀♀, BIOICE Stn 2849; five non-ov. ♀♀, three prep. ♂♂, BIOICE Stn 2853; eight non-ov. ♀♀, three prep. ♂♂, BIOICE Stn 3280; four non-ov. ♀♀ (one dissected on microslide), BIOICE Stn 3282; three non-ov. ♀♀, BIOICE Stn 3518; one non-ov. ♀, BIOICE Stn 3528; two non-ov. ♀♀ BIOICE Stn 3531; three non-ov. ♀♀, one prep. ♂, BIOICE Stn 3532 .

Size

Non-ovigerous female. Body length 2.44–3.64 mm, cf. 2.7 mm, Hansen (1913), and 3.2 mm, Guerrero-Kommritz (2005). Preparatory male: body length 2.96–3.16 mm.

Distribution records from the AFEN, BIOICE and BIOFAR area

Eleven records from the BIOICE survey: three from the Irminger Basin 1042–1209 m, eight from the Iceland Basin, 988–1840 m. All have positive bottom temperatures of 2.4–4.2°C, with various sediment types including ‘clay’, ‘silty sand’, and ‘shell-sand’ .

Distribution elsewhere

Originally described from Forsblad Fjord, East Greenland, 73–165 m ( Hansen 1913); other records are from Jörgen Brönlund Fjord, East Greenland, 160–180 m ( Just 1970), and the Greenland Sea, 188–191 m ( Guerrero-Kommritz 2005).

Remarks

This species of Chauliopleona is characterised by a relatively slender cheliped carpus that has a low-aspect ratio (shallow) sub-rectangular shield ( Figure 3H ) and a slightly recurved sternal process on pleonites 1–4 ( Figure 2C ). The basal setae of the maxilliped ( Figure 3G ) are also relatively short compared to those in C. armata and C. hastata . There is some discrepancy between the present specimens and the specimen illustrated by Guerrero-Kommritz (2005) in the size of the inferior propodal spinules on pereopods 1–3: his material, one specimen from the Greenland Sea, has robust spinules (also on the carpus), whereas the current material has both weak and moderate setules ( Figure 4A–C ). This better corresponds to Hansen’ s description of ‘second pair of legs [pereopod-1] without spinules on the posterior margin of sixth joint [propodus]’ ( Hansen 1913, p. 81). The presence of a distomedial seta on the carpus of pereopods 2–3 is another possible distinguishing character from C. armata and C. hastata .

This species is partly sympatric with C. armata and C. hastata in the Irminger Basin and its depth and geographic distributions indicate polar emergence.

Figures

Figure 2. Chauliopleona amdrupii. Non-ovigerous female, BIOICE Stn 3282: (A) habitus; (B) pleonal sternites, lateral; (C) antennule; (D) antenna; (E) pleopod endopod (setae very finely plumose, omitted for clarity; and following); (F) pleopod exopod; (G) uropod. Scale bar: 1 mm for A; 0.5 mm for B; 0.25 mm for C–G.

Figure 3. Chauliopleona amdrupii. Non-ovigerous female, BIOICE Stn 3282: (A) labrum; (B–C) left mandible and molar; (D) right mandible; (E) maxillule; (F) maxilla; (G) maxilliped (one palp omitted); (H) cheliped. Scale bars: (i) 0.25 mm for A–G; (ii) 0.25 mm for H.

Figure 4. Chauliopleona amdrupii. Non-ovigerous female, BIOICE Stn 3282: (A–F) pereopods 1–6 respectively. Scale bar 0.25 mm.

Figure 18. Distribution of Chauliopleona species in the Atlantic Margin area. Filled triangles C. amdrupii, filled squares C. armata, and filled circles C. hastata; crosses indicate Ingolf records of C. hastata.