Bathyporeia griffithsi, D’Acoz & Vader, 2005

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 : 2779-2785

Bathyporeia griffithsi sp. nov.

( Figures 16–21 )

Etymology

The species is dedicated to Prof. Charles L. Griffiths who suspected it was new. The name is a genitive.

Material examined

Holotype: one adult female dissected and mounted on 11 slides, Namibia, Langstrand , 22 ° 049S, 14 ° 109E, 7 August 1998, previously identified as ‘‘ Bathyporeia n. sp.?’’ by C. L. Griffiths, SAM 43 815 . Paratypes: one adult male and two adult females, Namibia, Langstrand , 22 ° 049S, 14 ° 109E, 7 August 1998, previously identified as ‘‘ Bathyporeia n. sp.?’’ by C. L. Griffiths, SAM 43 815.

Description

Species rather slender. Eye with well-developed ommatidia in adults. Pseudorostrum with rounded tip, narrow, not overhanging, with two to three proximoventral setae in adults; development and number of apical spines normal. Major flagellum of A1 with six to seven articles in females, 10 in male; first article of accessory flagellum with one to three nonapical groups of spines. Flagellum of A 1 in males rather long (combined length of major flagellum and distal two articles of peduncle 1.7 times as long as pseudorostrum). Anterior border of third article of peduncle of A2 with one group of spinules and setae in apical position only or with one single narrow seta more proximally; article 4 with lateral and apical spinules; flagellum with seven to eight articles in female, 30 in male. A2 of adult male longer than body length, with flagellum four times as long as peduncle.

Penultimate article of mandibular palp elongate.

Third article of maxilliped palp with longitudinal row of setae on dorsal side (and two transverse groups of anterior setae); inner plate with eight strong setae on dorsal surface; outer plate with six nodular spines.

Coxa 1 with tip narrowly rounded, without ventral tooth, without anteroventral angular discontinuity, with well-developed ventral setae, without apical setule.

Coxa 2 with small posterior tooth which may be separated from coxa by a deep or a shallow notch; transition between anterior and ventral borders with angular discontinuity; anterior border straight; anterior and posterior borders parallel; ventral border with eight regular-sized setae of normal length and width (except seta associated with tooth, which is reduced to a setule); no medial setae in dissected specimen.

Coxa 3 without posterior tooth; anterior and posterior border parallel; ventral border with 12 rather regular-sized setae in adult females, of normal width and length, six medial setae.

Coxa 4 with 19 regular-sized setae, of normal width and length; posterior setae not setulose.

P3 with carpal fang just overreaching tip of propodus, distally styliform, without accessory setule; propodus rather slender; outer spines/setae of propodus in normal number (eight), of normal size and shape; dactylus slender, with rather short unguis, with posterior border barely concave (straight if the unguis is not considered). Propodus of P3 longer than propodus of P4. Ratio of propodus length and merus length of P 3 in adult female: 0.93. Ratio of dactylus length and propodus length of P 3 in adult female: 0.32. Ratio of length and width of dactylus of P 3 in adult female: 4.6. Ratio of unguis length and total length of dactylus of P 3 in adult female: 0.23. Ratio of unguis length and dactylus width in P3 of adult female: 1.0.

P4 with carpal fang not reaching tip of propodus, distally styliform, without accessory setule; propodus of normal robustness; outer spines/setae of propodus in normal number (eight), of normal size and shape; dactylus rather slender, with rather short unguis, with posterior border barely concave, with scarcely distinct median convexity.

Median part of anterior border of basis of P5 weakly convex; merus elliptic but not unusually broad (2.2 times as long as broad); posteromedian seta group of merus with one long and strong major seta and one 0.2–0.3 times as long non-setulose accessory seta; posterodistal seta group with one long and strong straight seta (nearly reaching tip of carpus), and one well-developed setule (no sexual dimorphism); longest posterior spine of carpus overreaching tip of propodus.

Posterodistal lobe of basis of P6 protruding; anterior border regularly convex; posterior border distinctly convex; in females, anterior border with narrow setae on proximal 0.5, with spiniform setae on distal 0.5. Merus of P6 with three (sometimes only two) posterior groups of spines/setae and five to six anterior groups; longest seta of each anterior seta group not of significantly increasing size towards distal part of merus; carpus without posterior spines (distal group not considered); propodus with two posterolateral, and two anteromedial groups of spines (terminal crown of spines not considered). Spines of carpus and merus long and of normal robustness. P7 with anterior and posterior border of basis almost straight, parallel; posterior border of basis with robust ornamentation (spines) except proximally and distally where the spines are replaced by longer spiniform setae; seven spines/setae; medial side with pappose setae and minute spines in females. Ischium short, reaching 0.34 of outer side of merus; anterodistal border barely concave on outer side, distinctly concave on medial side; posterodistal border straight both on outer and medial side. Spines of carpus and merus of normal length and robustness.

Middle of posterior border of Ep1 and Ep2 distinctly angular but not produced as tooth.

Ep3 with posteroventral border regularly rounded, without posteroventral tooth, with ventrolateral ornamentation consisting of three single spines and a transverse row of two spines; one ventral setule; one setule on posterior border (i.e. a low number).

Urosomite 1 with one pair of anteriorly directed setae, and two (sometimes one) pairs of posteriorly directed spines dorsally; ventrolateral border without strong setae arising from outer side.

Peduncle of uropod 1: outer dorsal border with six to eight spines consisting of following succession: (1) four to six short robust spines, (2) the usual penultimate short robust spine, (3) very short space followed by very strong distal spine; dorsomedial border with four single styliform spines. Rami of normal length and rather slender; inner ramus with border facing outer ramus, with only one long spine in subdistal position. Spines on rami neither especially stout nor especially slender.

Peduncle of uropod 2 of normal proportions; outer dorsal border with four to five short and robust spines; dorsomedial border with two narrow single spines. Rami of normal length and robustness; inner ramus with border facing outer ramus with only one long spine in subdistal position. Spines on rami neither especially stout nor especially slender.

Peduncle of uropod 3 with longest distal spine almost reaching tip of inner ramus (endopodal spines excluded); outer border of peduncle of uropod 3 with two groups of one to two slender setae. Inner ramus elliptic, with two spines (one short and one long). Outer ramus with first article narrow, second article long and narrow. Second article of outer ramus with three to four medial setae, without outer setae. Medial side of outer ramus (first and second articles together) with 11–12 long, plumose setae; accessory spiniform nonsetulose setae may be present; all plumose setae much longer than longest setae on outer side. Outer side of outer ramus (first and second article together) with three to four groups of two spiniform setae, much shorter than outer ramus width. Ratio between length of second article and length of first article: 0.41. Ratio between length of second article and width of first article: 1.8.

Telson of typical morphology; lobes without medial setae.

Colour in life. Unknown, but eye very dark in alcohol.

Size. 4 mm. Ecology. Concerning the ecology of this species, C. L. Griffiths provided us with the following information: ‘‘The beach … is a wave exposed beach of clean sand with grain size 280 microns and intertidal width 35 m. I do not know exactly what height the sample came from, but given the situation with related species I strongly suspect it would be from the low intertidal. I do not think any samples were taken below low water’’.

Distribution. Namibia.

Discussion

It is difficult to express an opinion concerning the affinities of this species. None of its individual characters is really special, although their combination is unique. However, to a certain extent it seems to exhibit some similarities with B. pelagica , B. elegans , and B. phaiophthalma . The tooth/notch pattern of its coxae 1–3 is somewhat similar albeit not identical with that of B. pelagica . The robustness of the posterior spines of the basis of the seventh pereiopod is similar to B. pelagica and B. elegans . The absence of a tooth on the third epimeral plate is shared with B. elegans and B. phaiophthalma but not with B. pelagica . However, a rather uncommon character is the presence of a quite long and narrow second article on the outer ramus of the third uropod with well-developed setation on the medial side and no setae on the outer side. This condition is also observed in B. phaiophthalma .

Figures

Figure 16. Bathyporeia griffithsi sp. nov. Ovigerous female, holotype, Namibia, Langstrand: (A) Head; (B) left A1; (C) right A2; (D) right Md; (E) incisor process of left Md; (F) left Mxp; (G) right P1 (most setae not shown); (H) left P2 (setae not shown except the most proximal one of propodus). Scale bar: 0.21 mm (A–C, G); 0.14 mm (D, E); 0.10 mm (F); 0.35 mm (H).

Figure 17. Bathyporeia griffithsi sp. nov. Adult females, Namibia, Langstrand: (A–E, G–I, K, L) holotype; (F, J) paratype. (A) Left coxa 1; (B) right coxa 1; (C) right coxa 2; (D) posteroventral angle of right coxa 2; (E, F) posteroventral angle of left coxa 2; (G) left coxa 3; (H) posteroventral angle of left coxa 3; (I) posteroventral angle of right coxa 3; (J) posteroventral angle of left coxa 3; (K) left coxa 4; (L) telson. Scale bar: 0.15 mm (A–C, G); 0.025 mm (D–F, H–J); 0.21 mm (K); 0.125 mm (L).

Figure 18. Bathyporeia griffithsi sp. nov. Ovigerous female, holotype, Namibia, Langstrand. (A) Left P3 (setae and spines not shown except carpal fang); (B) anterior part of left P3 (medial spines/setae of propodus not shown); (C) dactylus of left P3; (D) left P4 (setae and spines not shown except carpal fang); (E) anterior part of left P4 (medial spines/setae of propodus not shown); (F) dactylus of left P4; (G) dactylus of right P4; (H) carpal fang of right P4. Scale bar: 0.42 mm (A, D); 0.10 mm (B, E); 0.05 mm (C, F–H).

Figure 19. Bathyporeia griffithsi sp. nov. Ovigerous female, holotype, Namibia, Langstrand. (A) Right P5; (B) right P6; (C) left P7; (D) basis and ischium of right P7 (medial view). Scale bar: 0.26 mm (A–C); 0.21 mm (D).

Figure 20. Bathyporeia griffithsi sp. nov. Ovigerous female, holotype, Namibia, Langstrand. (A) Right Ep1; (B) left Ep2; (C) right Ep3; (D) urosomite 1 (left side); (E) right U1; (F) left U2; (G) left U3. Scale bar: 0.21 mm (A–D); 0.14 mm (E, F); 0.18 mm (G).

Figure 21. Bathyporeia griffithsi sp. nov. Adult male, paratype, Namibia, Langstrand. (A) Head (right side) with A1, proximal part of A2 and mandibular palp; (B) right A2; (C) posteroventral angle of right coxa 2; (D) posteroventral angle of right coxa 3; (E) distal part of P5; (F) urosomite 1 (right side) and peduncle of U1. Scale bar: 0.21 mm (A, E, F); 0.42 mm (B); 0.1 mm (C, D).