Chauliopleona bamberi, Bird, 2015

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 : 18-24

Chauliopleona bamberi n. sp.

( Figures 8–10 , 19 )

Chauliopleona sp.AM#1: Bird 2001 (unpubl.), not Chauliopleona sp.AM#1 sensu Bird 2014

Diagnosis

Cephalothorax elongate, 1.6 times ltb. Pereonites all shorter than broad; with parallel lateral margins. Pleon shorter than cephalothorax, without posteriodorsal protuberances; pleonites 1–4 with recurved sternal process. Antennule article-1 as long as rest of antennule. Antenna article-4 without suture. Maxilliped basis with long seta. Cheliped merus without inferior protuberance; carpus fairly slender, 1.8 times ltb, inferior shield shallow (aspect ratio ≈ 0.2), rounded, distal margin not angular; fixed finger with four teeth; dactylus superior margin crenate or nodulose. Pereopods 1–3 propodus slender, about six times ltb; carpus and propodus inferior spinules sparse and weak, or absent. Pereopods 2–3 carpus without distomedial seta. Pereopods 4–6 ischium with one long seta (of two). Uropod exopod half as long as endopod segment-1; endopod about three times length of peduncle.

Material examined

Holotype. Non-ov. ♀, AFEN Stn 53919#2/3, West Shetland Shelf, 168 m, NMS. Z.2014.165.

Allotype. Prep. ♂, AFEN Stn 53815, NMS.Z.2014.166 . Paratypes. AFEN Stns: two non-ov. ♀♀ , one ov. ♀, one prep. ♂, Stn 53815#4/5, NMS.Z.2014.167.1; one non-ov. ♀ , 53816#4, NMS.Z.2014.167.2; one non-ov. ♀ , 53885#2, NMS.Z.2014.167.3; one non-ov. ♀ , 54612#2, NMS.Z.2014.167.4; one non-ov. ♀ , one prep. ♂, 54615#1, NMS.Z.2014.167.5; one non-ov. ♀ , 54621#7/9, NMS.Z.2014.167.6; one non-ov. ♀ , one prep. ♂, 57018#2, NMS.Z.2014.168.1; one non-ov. ♀ , 57020#1, NMS.Z.2003.114.0032; one prep. ♂ , 57023#1, NMS. Z.2003.114.042; one ov. ♀ , 57082#1, NMS.Z.2014.168.2; one non-ov. ♀ , 57100#2, NMS.Z.2014.168.3.

Other material. North Sea : eight non-ov. ♀♀ , one ov. ♀, eight prep. ♂♂, one swimming ♂ (?).

Description

Female: habitus ( Figure 8A ) slender, 7.4 times ltb; non-ovigerous body length 1.8–3.0 mm (n = 19); ovigerous body length 2.5–2.6 mm (n = 3).

Cephalothorax longer than pereonites 1–2 combined, 1.6 times ltb. Pereon with pereonites with scarcely concave lateral margins or parallel-sided, all shorter than broad, pereonites 1 and 6 shortest, subequal, pereonites 2–3 longest. Pleon ( Figure 8B–C ) as long as pereonites 5–6 combined, epimera with seta, sternites 1–4 with recurved process, sternite-5 with recurved spur reaching uropod attachments. Pleotelson about as long as pleonites 4–5 combined, setation typical.

Antennule ( Figure 8D ) about 0.6 times length of cephalothorax; article-1 as long as distal articles combined, three times ltb; article-2 twice as long as broad, with lateral seta longer than article; article-3 half as long as article-2, with two setae; article-4 slender, just longer than article-2, with six setae and aesthetasc; without caplike terminal segment; other setation as figured. Antenna ( Figure 8E ) about 0.75 times length of antennule; article-2 with superior and lateral setae; article-3 half as long as article-2; article-4 about seven times ltb, with pseudo-suture; article-5 about as third as long as article-4; article-6 small, as long as broad; other setation as figured.

Labrum ( Figure 9A ) typical, hood-shaped, distally setulate. Mandibles ( Figure 9B–C ) typical, molar process of both acuminate, with rosette of terminal spines; incisors weakly tricuspid, left mandible with acuminate lacinia mobilis. Labium ( Figure 9D ) typical, outer lobes reduced, naked; inner lobes distally setulate. Maxillule ( Figure 9E–F ) typical, endite with nine spines four of which are pectinate. Maxilla ( Figure 9G ) simple, as long as maxilliped bases. Maxilliped ( Figure 9H–J ) basis with long distal seta; endite with medial cusp, lateral seta, and medial coupling hook; palp article-1 as long as article-2, naked; article-2 with lateral seta reaching beyond article-3; article-3 with four unequal mesial setae; article-4 shorter and narrower than article-3 with superodistal seta and five terminal; setae. Epignath ( Figure 9K ) simple, elongate.

Cheliped ( Figure 9L–M ) basis with posterior lobe about as long as anterior mass; carpus 1.8 times ltb, carpal shield shallow, aspect ratio 0.22; chela longer but as wide as carpus, fixed finger incisive margin with four teeth; dactylus superior margin nodulose.

Pereopod-1 ( Figure 10A ) typical; merus and carpus with few, or no, setules; propodus slender, six times ltb, 1.7 times longer than carpus, setules sparse; dactylus and unguis together 0.75 times length of propodus. Pereopod-2 ( Figure 10B ) typical; carpus without distomedial seta; propodus slender as in pereopod-1. Pereopod-3 ( Figure 10C ) similar to pereopod-2.

Pereopod-4 ( Figure 10D–E ) typical; basis with one inferior PSS (not figured); ischium with two unequal setae; merus and carpus with sparse setules; dactylus and unguis together just longer than propodus. Pereopod-5 ( Figure 10F ) similar to pereopod-4, basis three times ltb, with two inferior PSS. Pereopod-6 ( Figure 10G– H ) similar to pereopod-5 but basis with one inferior PSS; propodus with three slender superodistal spines; dactylus and unguis as long as propodus.

Pleopod ( Figure 10J–K ) relatively small; endopod slightly narrower and shorter than exopod, with superodistal seta and distal fringe of seven setae (all finely plumose); exopod with proximal seta separated from distal fringe of 10 finely plumose setae.

Uropod ( Figure 8F ) peduncle over twice as long as broad; endopod slender, segment-1 1.6 times longer than peduncle, as long as segment-2; exopod slender, just shorter than peduncle, segment-1 just shorter than segment-2.

Preparatory male. Habitus ( Figure 8G ) similar to female but showing typical dimorphic characters; body length 1.8–2.5 mm (n = 13). Antennule ( Figure 8H ) article-1 2.4 times ltb.

Etymology

For my much esteemed colleague Dr. Roger Bamber, for his tireless work and contributions on Tanaidacea (and much else besides).

Type locality

West Shetland Shelf, ≈ 61.50°N, 1.00°W, ≈ 200 m.

Distribution records from the AFEN, BIOICE and BIOFAR area

Eleven records from the AFEN surveys: nine from the North and West Shetland Shelf and Slope, 120–243 m, and two from the Hebrides Slope, 301–398 m, in sandy substrata .

Distribution elsewhere

North Sea (via Roger Bamber); no site data available.

Remarks

Until the publication of Chauliopleona bamberi n. sp., three species of this genus had originally been recorded with a nodulose or crenate superior margin of the cheliped dactylus: C. dentata , C. paradoxa and C. sinusa , but with the discovery of the female of C. hansknechti, Błażewicz-Paszkowycz, Bamber, Jóźwiak (2012) showed that this also has a finely crenulate cheliped dactylus. Chauliopleona bamberi is therefore the most similar of the four known northeast Atlantic Chauliopleona to the type species in possessing this character. This is also shared by several species in Akanthophoreus and Parakanthophoreus . The relatively long cephalothorax and slender, almost smooth, propodus of pereopods 1–3 appear to be other useful or diagnostic characters.

The records from west of the Shetland Isles at shelf and shelf-break depths, 120– 243 m, mean at least that it is another (somewhat unexpected) addition to the shallow-water fauna (<200 m) from the British Isles, following the discovery of Zeuxo holdichi Bamber, 1990 in the Scilly Isles ( Bamber 2011). Twenty-seven species were reported by Holdich and Jones (1983) with additions made by Jones and Holdich (1983) and Holdich and Bird (1986), bringing the published total now to 32. It is probable that this species is the source of some records of ‘ Leptognathia gracilis ’ or ‘ Akanthophoreus ’ in British waters if the pleonal spur was not observed. In the outer shelf and shelf-break area from where C. bamberi has been found, the tanaidacean fauna is sparse ( Bird 2001) and same-sample records include Akanthophoreus gracilis sensu lato, Araphura brevimanus ( Lilljeborg, 1864) , Akanthophoreus longiremis ( Lilljeborg, 1864) and Tanaopsis graciloides ( Lilljeborg, 1864) , in descending order of abundance (all lower than that of C. bamberi ). The first and last of these taxa have a crenulate cheliped dactylus.

Figures

Figure 8. Chauliopleona bamberi n. sp. Non-ovigerous female, holotype, AFEN Stn 53919#2/3. (A) habitus; (B) pleon and pleotelson, lateral; (C) pleonite-5 sternal spur. Ovigerous female paratype, AFEN Stn 53815: (D) antennule; (E) antenna; (F) uropod. Preparatory male, allotype, AFEN Stn 53815: (G) cephalothorax–pereonite-1; (H) antennule. Scale bars: (i) 1 mm for A, G; (ii) 0.5 mm for B–C, 0.25 mm for D–F, H.

Figure 9. Chauliopleona bamberi n. sp. Ovigerous female, paratype, AFEN Stn 53815: (A) labrum; (B–C) left and right mandibles, respectively; (D) labium; (E) maxillule; (F) maxillule endite spines; (G) maxilla; (H) maxilliped (one palp omitted); (J) maxilliped endite; (K) epignath; (L) cheliped; (M) cheliped propodus mesial comb and dactylus. Scale bars: (i) 0.25 mm for A–K; (ii) 0.25 mm for L–M.

Figure 10. Chauliopleona bamberi n. sp. Ovigerous female, paratype, AFEN Stn 53815: (A–C) pereopods 1–3, respectively; (D) pereopod-4 ischium; (E) pereopod-4, basis omitted; (F) pereopod-5; (G–H) pereopod-6 basis and propodus-claw, respectively; (J) pleopod endopod (setae very finely plumose, omitted for clarity; and following); (K) pleopod basal article and exopod. Scale bar: 0.25 mm.

Figure 19. Distribution of Chauliopleona bamberi and Saurotipleona julii in the Atlantic Margin area. Filled squares indicate C. bamberi, and filled circles S. julii.