Bathyporeia, Lindstrom, 1855

D’Acoz, Cédric D’Udekem & Vader, Wim, 2005, New records of West and South African Bathyporeia, with the description of four new species and a key to all species of the genus (Crustacea, Amphipoda), Journal of Natural History 39 (30), pp. 2759-2794 : 2761

Bathyporeia complex tenuipes Meinert, 1877

Composition

Bathyporeia cheυreuxi sp. nov., B. cunctator sp. nov., B. lindstromi Stebbing, 1906 , B. tenuipes Meinert, 1877 .

Diagnosis

Body and appendages slender. Anteroventral spines of pseudorostrum short and few in number. Eye with numerous well-developed ommatidia in adults. Articles of major flagellum of A 1 in adult males dramatically decreasing in diameter from base to tip of flagellum. Third article of peduncle of A2 with at least two groups of spines or spiniform setae. A2 longer than body in adult males. Penultimate article of maxillipedal palp without longitudinal dorsal row of setae. Inner plate of maxilliped with two to four strong setae on dorsal surface (most commonly four). Ventral margin of coxa 1 toothless or with notch, never with a true tooth. Coxae 2–3 with strong posterior tooth. Some ventral setae of coxae 2–3 quite robust. Coxa 2 with a very characteristic triangular/trapezoidal shape. Propodus of P3 and P4 subequal. Carpal fang of P3–P4 entire, with acute tip. Dactylus of P3–P4 long, slender with long unguis, with posterior border distinctly concave. Basis of P5 with anterior and posterior border distinctly and similarly convex. Merus of P5 broad to very broad, with posterodistal seta group with one short spiniform seta in males and in females (both in adults and in immatures). P6 basis with anterior and posterior border distinctly convex, with posterodistal lobe well developed. Anteromedial setae of merus of P6 especially well developed. Carpus and propodus of P6 quite long and slender. Posterior border of carpus of P6 with at least one group of spines in addition to the distal one. P7 long and slender. Basis of P7 with a fairly large number of posterior setae. Medial face of basis of P7 with pappose setae only, without spines. Ischium of P7 quite long and acute with anterior border distinctly concave. Ep1–Ep2 with middle of posterior border angular. Ep3 without posterior tooth. Urosomite 1 usually with two to four (rarely one) posteriorly directed spines. Outer ventral part of urosomite 1 with several strong setae. Outer dorsal border of peduncle of U1 with long slender spines or setae on proximal half and short and stockier spines on distal half. Inner rami of U1–U2 with border facing outer ramus, with only one long spine in subdistal position. U3 with especially long spines and setae on outer border. Second article of U3 long with spines/setae on both sides. Medial side of U3 usually with short and narrow accessory spiniform setae.

Discussion

The tenuipes complex is quite distinct from any other Bathyporeia taxon, being only distantly related to B. gracilis G. O. Sars, 1891 , a species redescribed by d’Udekem d’Acoz (2004). On the other hand, the tenuipes complex itself is perhaps the most difficult case to unravel taxonomically within the, already difficult, genus Bathyporeia . It has an extremely wide distribution, from Denmark to South Africa and to the Mediterranean Sea and it is morphologically extremely homogeneous throughout its range. On first examination, we were tempted to lump all the material available into one species, B. tenuipes . However, it appeared that the typical B. tenuipes from north-west Europe had slightly shorter dactyli than the warm-temperate and tropical populations. Therefore, d’Udekem d’Acoz and Vader (forthcoming) admitted two species: B. tenuipes from north-west Europe and B. lindstromi from the Mediterranean and probably the West African coast. However, after a second look at the African material it appeared that small but consistent differences could be observed between the South African, the Senegalese, the Mediterranean and the northwestern European material. These differences can only be appreciated when good samples of properly fixed material are available. The existence of a single Mediterranean/pan-east- Atlantic species seemed a priori unlikely and we have therefore decided to consider these four groups of populations as different species. The Senegalese and the South African forms are therefore reluctantly described as new, respectively under the names B. cheυreuxi sp. nov. and B. cunctator sp. nov. This choice is of course debatable, and other carcinologists could argue that the forms of the complex tenuipes are mere local intraspecific variations or subspecies. The differences between the four species are listed in Table I. Comparative figures of essential characters have been given for B. lindstromi ( Figure 9 ) and B. tenuipes ( Figure 10 ). More detailed figures of those species can be found in d’Udekem d’Acoz and Vader (forthcoming) for the former and d’Udekem d’Acoz (2004) for the latter.

Figures

Figure 9. Bathyporeia lindstromi Stebbing, 1906, females, Italy: (A, G) MVRCr, Toscana, Piombino, station T2, 4–8 m depth, April 1978, leg. Cognetti; (B, C, D) MVRCr, Caffè di Napoli, 11 m depth, 6 August 1892, leg. A. Della Valle; (E, F) MVRCR, ‘‘Napoli 22’’, Ischia, Spiaggia degli Inglesi, fine sand, 4–5 m depth, 1 August 1969, leg. Ulrich Schiecke. (A) Proximal part of right A1; (B) proximal part of left A1; (C) anterior part of right P4 (medial spines/setae of propodus not shown); (D) distal part of left P5; (E) proximal part of right P7; (F) posterior border of basis of right P7 (medial view); (G) ventral part of first urosomite and peduncle of right U1 in outer view (medial spines not shown). Scale bar: 0.21 mm (A, B, G); 0.10 mm (C); 0.30 mm (D); 0.42 mm (E); 0.17 mm (F).

Figure 10. Bathyporeia tenuipes Meinert, 1877, females, Ireland, Galway Bay, station GB 49, Decca coordinates R.E.16/G.A.44, sand, 77 m depth, Dave McGrath leg., DM. (A) Proximal part of right A1; (B) anterior part of right P4 (medial spines/setae of propodus not shown); (C) distal part of left P5; (D) proximal part of left P7; (E) posterior border of basis of left P7; (F) ventral part of first urosomite and peduncle of right U1 in outer view (medial spines not shown). Scale bar: 0.21 mm (A, E, F); 0.10 mm (B); 0.42 mm (C, D).