Pseudaeginella telukrimau sp. n., a new species of caprellid (Crustacea: Amphipoda) from Malaysia Author Lim, Jacqueline Hui Chern Author Azman, Bin Abdul Rahim Author Takeuchi, Ichiro Author Othman, Bin Haji Ross text Zootaxa 2017 4282 1 journal volume 28696 10.11646/zootaxa.4282.1.3 798ad3a2-4340-4802-abb7-1e0116da6f64 1175-5326 818425 C7F17741-EE5A-4B19-86AB-1E69948DB7A8 Pseudaeginella telukrimau sp. n ( Figs. 1–5 ) Type materials. Holotype , Male , 3.24 mm , UMTCrus00473 ( Fig. 1 ), coral reef, Teluk Rimau , Pulau Besar , Johor , 02°27.594'N ; 103°58.705'E ; diving, 25 March 2010 , 11.51 am, depth 7.7 m ; coll. Azman, B.A.R , Gan, S.Y. , Lim, J.H.C. , Khoo, M.L. & Shamsul B. Allotype , Female, UMTCrus00474 ( Fig. 4 ), same locality as male. Paratypes, 15 males, UMTCrus00475; 28 females, UMTCrus00476; 48 premature males, 24 premature females, UMTCrus00477; same station data. Type locality. Teluk Rimau , Pulau Besar , Johor , Malaysia . Description. Male, Body length, 3.24 mm . UMTCrus00473. Head, 0.33 mm and pereonite 1, 0.285 mm ; head and pereonite 1 partially fused (suture clear); head with 1 long anteriorly curved dorsal projection; pereonite 1 with 1 small dorsodistal acute triangular projection. Pereonite 2, 0.53 mm with a pair of anteriorly curved mid-dorsal projections, a small anterolateral projection and an unpaired dorsodistal round projection. Pereonite 3, 0.69 mm , longest, with 1 pair of round mid-dorsal projection, 1 anteroventral triangular projection, 1 mid-lateral truncateliked projection, 1 mid-ventral triangular projection and 1 dorsodistal round projection. Pereonite 4, 0.54 mm , subequal with pereonite 2 with 1 pair of round mid-dorsal projection, 1 anteroventral triangular projection, 1 midlateral truncate projection, 1 mid-ventral triangular projection, 1 ventrodistal triangular projection and 1 pair of round dorsodistal projection. Pereonite 5, 0.45 mm with 1 pair of triangular mid-dorsal projection, 1 small anteroventral triangular projection and 1 pair of mid-ventral triangular projection. Pereonite 6 and 7 not fused. Pereonite 6, 0.22 mm with 1 mid-dorsal acute triangular projection, one small mid-lateral round projection and one small anteroventral triangular projection. Pereonite 7, 0.19 mm with no projections. Antenna 1 , 0.6 x body length; peduncular article 2 longest, 1.35 x article 1 with several setae; article 3 shortest, 0.32 x article 2; flagellum 1.18 x peduncle with 10 articles, proximal article composed of 2 articles. Antenna 2 , 0.33 x body length and 0.5 x antenna 1; peduncular article one shortest with ventrodistal projection; article 2 with several setae at ventrodistal corner; article 3, 0.28 x article 2 with several setae; article 4 longest, 1.29 x article 3; flagellum with 2 articles, 0.18 x peduncle with tuft of 8 setae at distal margin. Upper lip notched, wider than deep, forming rounded projections. Lower lip well developed, inner lobe partially fused with a cleft medially, outer lobes rounded without setae, provided with a wing-liked projection medially on each side. Mandible right incisor with 5 teeth followed by lacinia mobilis with many small teeth and 2 serrated trapezoid structures and one accessory bundles setae; molar absent; palp 3-articulate; article 2, 2.1 x article one with one distal seta; article 3 subequal with article 2 with setal formula 1-5-1 and one distal knob. Mandible left incisor with 5 teeth followed by three serrated trapezoid structures and 1 accessory bundled seta; molar absent; palp 3-articulate; article 2, 2.19 x article 1 with one distal seta; article 3 subequal with article 2 with setal formula 1-5-1 and one distal knob. Maxilla 1 outer plate with 6 stout apical setal-teeth; palp biarticulate, article 2, 2.45 x the length of article 1 with 2 triangular projections at distal margin, armed with 2 slender setae and 1 plumose seta; facially with 1 normal seta. Maxilla 2 inner plate with 5 long and short apical setae; outer plate with 5 apical setae. Maxilliped basal endite (inner plate) deeper than wide, subrectangular with 1 stout tooth, 1 normal seta and 1 long facial seta; ischial endite (outer plate) 1.56 x inner plate with 2 setae on inner margin and 3 normal setae distally; palp 4 articulate; article one with one seta on inner margin; article 2, 1.55 x article 1 with 2 short setae and 1 long seta on inner margin; article 3 subequal with article 2 with 6 distal setae; palp article 4 (dactylus) falcate with 1 proximal seta on outer margin and 2 setae at distal margin; inner margin with row of fine setae. Pereon. Gnathopod 1 basis shorter than ischium, merus and carpus combined, 0.74 x pereonite 1, sparsely setose; ischium 0.31 x basis with one plumose seta at posterodistal corner; merus with 2 short and 2 long plumose setae at posterodistal corner; carpus subequal with merus, equipped with a row of 5 distal plumose setae; propodus longer than wide (1.8 x width) with 2 rows of submarginal plumose setae and group of long and short setae at distal margin, palm begins 1/4 along posterior margin with a pair of robust/stout proximal setae and several short and long setae along entire margin; dactylus falcate with sparse and fine setae on inner margin, distally with 1 teeth and 3 tubular setae. Gnathopod 2 , 3.3 x longer than gnathopod 1, robust, begins 2/5 along anterior margin of pereonite 2; coxa weakly lobated; basis longer than ischium, merus and carpus combined, 0.97 x the length of pereonite 2 with an acute anterodistal projection provided with 3 small setae; ischium subrectangular with 1 large trapezoid anterior projection provided with 3 weak triangular projections and small setae distally; merus subsemicircular with 2 setae on posterior margin; carpus subtriangular with 2 small setae; propodus large, subovate, nearly as long as basis (0.86 x length of basis) sparsely setose, palm begins 1/7 along posterior margin, proximal projection with 1 robust seta (grasping spine) and one slender seta, mid palmar triangular projection with one small seta followed by a triangular sinus and 2 smaller triangular projections, palm with several short and long setae along entire margin; dactylus falcate, with several fine setae on inner margin. Gill 3 length 0.45 x the length of pereonite 3, oval. Pereopod 3 very small, 1-articulate, 0.08 x gill 3 length, conical in shape with 2 setae apically. Gill 4 subequal in length with gill 3, 0.57 x the length of pereonite 4, oval. Pereopod 4 subequal in length with pereopod 3, 1- articulate, conical with 1 long seta apically. Pereopods 5–7 well developed, 6 articulate, becoming more robust progressively. Pereopod 5 basis with several setae on anterior margin; ischium with 1 anterodistal seta; merus expanding posterodistally with several seate on anterior and posterior margin; carpus subequal with merus with several setae, distally with 1 triangular projection; propodus longer than basis (1.13 x longer) with a pair of proximal grasping spines, palm with row of marginal setae, distally with several setae; dactylus falcate, with one plumose seta on anterior margin at proximal region. Pereopod 6 basis 1.17 x broader than basis of pereopod 5, with several setae on anterior margin; merus expanded posterodistally with 2 setae; carpus subcylindrical with row of paired setae on anterior margin, distally with 1 triangular projection; propodus 1.29 x longer than propodus of pereopod 5, proximal projection with 1 pair of grasping spines followed by a row of marginal robust setae on palm, distally with several long and short setae; dactylus falcate, with 1 plumose seta on anterior margin at proximal region. Pereopod 7 basis subequal in length with basis of pereopod 6, 1.14 x broader; ischium with setae at anterodistal corner; merus expanded posterodistally with 2 setae and row of marginal setae on anterior margin; carpus subrectangular with row of paired setae on anterior margin, distally with 1 triangular projection; propodus 1.2 x longer than propodus of pereopod 6, proximal projection with 1 pair of grasping spines followed by a row of marginal robust setae on palm, distally with several long and short setae; dactylus falcate, with several fine setae on inner and outer margin. FIGURE 1. Pseudaeginella telukrimau sp. n. , male, holotype, 3.24 mm, UMTCrus00473, Coral reef, Teluk Rimau, Pulau Besar, Johor. Scales for A1, A2 and G2 represent 0.2 mm; G1 and G1 magnified represent 0.1 mm; whole body represents 0.5 mm. FIGURE 2. Pseudaeginella telukrimau sp. n. , male, holotype, 3.24 mm, UMTCrus00473, Coral reef, Teluk Rimau, Pulau Besar, Johor. All scales represent 0.05 mm. FIGURE 3. Pseudaeginella telukrimau sp. n. , male, holotype, 3.24 mm, UMTCrus00473, Coral reef, Teluk Rimau, Pulau Besar, Johor. Scales for ABD (L), P3, P4 and P5 represent 0.1 mm; ABD (V) represents 0.05 mm, P6 and P7 represent 0.2 mm. FIGURE 4. Pseudaeginella telukrimau sp. n. , female, allotype, 3.28 mm, UMTCrus00474, Coral reef, Teluk Rimau, Pulau Besar, Johor. Scales for A1, A2 and G2 represent 0.2 mm; G1 and G1 magnified represent 0.1 mm; whole body represents 0.5 mm. FIGURE 5. Pseudaeginella telukrimau sp. n. , female, allotype, 3.28 mm, UMTCrus00474, Coral reef, Teluk Rimau, Pulau Besar, Johor. Scales for ABD (L), P3 magnified and P4 magnified represent 0.1 mm; ABD (V) represents 0.05 mm; P3, P4, P5, P6 and P7 represent 0.2 mm. Pleon. Penes semicircular, positioned medially. Uropod 1 ramus vestigial, degenerated into 2 short and 1 long setae. Uropod 2 ramus vestigial, with 3 setae, submarginally with 4–5 setae. Telson with a pair of plumose setae. Female. Body length, 3.28 mm . UMTCrus00474. Head length 0.37 mm and pereonite 1, 0.17 mm ; head and pereonite 1 partially fused (suture clear); head with 1 long anteriorly curved dorsal projection; pereonite 1 with 1 dorsodistal triangular projection. Pereonite 2, 0.63 mm with 1 pair of anteriorly curved mid-dorsal projections and an unpaired dorsodistal round projection. Pereonite 3, 0.68 mm , longest, with 1 anterodorsal round projection, 1 small anterior lateral projection, 1 mid-dorsal round projection, 1 dorsodistal round projection, posteroventral corner of pereonite 3 slightly pronounced. Pereonite 4, 0.57 mm , with 1 mid-dorsal round projection and 1 dorsodistal plate-like projection. Pereonite 5, 0.47 mm , with 1 pair of mid dorsal round projection, 1 anteroventral triangular projection. Pereonite 6, 0.19 mm , with 1 anteroventral triangular projection. Pereonite 7, 0.20 mm , with no projections. Antenna 1 , 0.63 x body length; peduncular article 2 longest, 1.4 x longer than article 1; article 3 shortest, 0.43 x shorter than article 2; flagellum with 10 articles, proximal article composed of 2 articles. Antenna 2 , 0.32 x body length and 0.5 x antenna 1; peduncular article one shortest with ventrodistal projection; article 2 with several setae at ventrodistal corner; article 4 longest; flagellum with 2 articles, article 2 shorter than article 1 (0.5 x shorter) with tuft of setae at distal margin. Pereon. Gnathopod 1 basis shorter than ischium, merus and carpus combined; merus with several setae at posterodistal corner; carpus 1.15 x merus with several setae on distolateral margin; propodus 2.06 x carpus with 2 rows of submarginal setae and several setae at distal margin, palm begins 1/4 along posterior margin with a pair of robust/stout proximal setae and several short and long setae along entire margin; dactylus falcate, distally with 1 tooth and 2 tubular setae. Gnathopod 2 , begins 1/5 along anterior margin of pereonite 2, coza weakly lobated; basis 1.75 x longer than ischium, merus and carpus combined; basis with 1 acute anterodistal triangular projection provided with 3 setae; ischium with 1 triangular projection at anterodistal margin; merus round with several setae; carpus subtriangular; propodus 0.88 x basis; palm begins 1/6 along posterior margin, proximal projection with 1 robust seta (grasping spine), mid palmar region with 1 small triangular projection followed by 2 smaller round projections, palm with several short and long setae, equipped with serratiform teeth between grasping proximal projection and mid-palmar projection; dactylus falcate, with several fine setae on outer and inner margin. Gill 3 length 0.62 x the length of pereonite 3, oval. Pereopod 3 , 0.03 x pereonite 3, 0.05 x gill 3 length, 1 articulate, conical, with 2 setae apically. Oostegite 3 , 1.13 x longer than wide, scarcely setose. Gill 4 , 0.67 x the length of pereonite 4, oval. Pereopod 4 subequal in length with pereopod 3, 0.07 x gill length, 1-articulate, conical, with 2 setae apically. Oostegite 4 , 1.08 x longer than wide, setose along entire margin. Pereopods 5–7 well developed, 6 articulate, becoming more robust progressively. Pereopod 5 carpus subequal in length with merus, distally with 1 projection; propodus subequal in length with basis, proximal projection with a pair of grasping spines, dactylus falcate, distal margin with tuft of setae. Pereopod 6 merus expanded posterodistally; carpus distal margin with 1 triangular projection; propodus proximal projection with 1 pair of grasping spines; dactylus falcate. Pereopod 7 merus expanded posterodistally; carpus subrectangular, distally with 1 triangular projection; propodus proximal projection with 1 pair of grasping spines followed by a row of marginal robust setae on palm; dactylus falcate, with several fine setae on inner and outer margin. Pleon. Uropod 1 ramus vestigial, degenerated into 1 setae. Uropod 2 ramus vestigial, with 2 setae. Telson with a pair of plumose setae Remarks. Species of Pseudaeginella are easily distinguishable from one another through observation of its body spinations or projections. Among the 11 species of Pseudaeginella , P . telukrimau sp. n. is closest to P . montoucheti ( Quitete, 1971 ) and P . tristanensis ( Stebbing, 1888 ) based on the numerous body spines/projections. Pseudaeginella montoucheti was first described as Fallotritella montoucheti by Quitete (1971) based on a male ( 3.2 mm ) and female specimen ( 2.9 mm ) collected from sargassum in Pernambuco , a state located northeastern of Brazil . Recently, Lacerda et al (2011) provided a detailed re-description of P. montoucheti collected from Santa Catarina , Brazil . Compared with Lacerda et al.’s (2011) description of P. montoucheti , the present species is similar to P. montoucheti in terms of its unpaired dorsodistal projections on pereonites 2 and 3, paired mid-dorsal projections on pereonites 2–4, 1 mid-ventral triangular projection over gill 3 and 4, 1 anteroventral triangular projection on pereonite 5, pereonite 7 without projections and basis of gnathopod 2 with 1 triangular projection but differs from P. montoucheti in terms of having 1 small anterolateral projection on pereonite 2 but no mid-lateral projection (paired acute anterolateral projection and paired acute mid-lateral projection in P . montoucheti ), presence of 1 anteroventral triangular projection on pereonites 3–4 (only present on pereonite 4 in P . montoucheti ), presence of 1 ventrodistal triangular projection on pereonite 4 (absent in P . montoucheti ), presence of a paired mid-dorsal and mid-ventral projection on pereonite 5 (only a paired mid-dorsal projection and a paired anterolateral projection in P . montoucheti ), pereonite 6 with mid-dorsal projections (absent in P . montoucheti ), antenna 1 more than half of total length (antenna 1 equal or shorter than half of body length in P . montoucheti ) and gnathopod 2 propodus width 0.53 x length (0.67 x in P . montoucheti ). P . telukrimau sp. n. , can be differentiated from P . tristanensis ( Mayer 1903 ; Laubitz 1995 ; Lacerda et al. 2011 ) by the following characteristics: i) mid-dorsal projections: Paired projections on pereonite 2–5 and 1 unpaired projection on pereonite 6 in P . telukrimau (unpaired on pereonites 2–6 in P. tristanensis ); ii) dorsodistal projections: Unpaired projection on pereonites 2–3 and paired projections on pereonite 4 in P . telukrimau (unpaired on pereonites 2–4 in P . tristanensis ); iii) mid-lateral projections: found on pereonites 3–5 in P. telukrimau (found on pereonites 2–4 in P . tristanensis ); iv) antenna 1: longer than half of total length in P . telukrimau (equals half body length in P . tristanensis ); v) total of projections on pereonites: more than 30 projections in P . telukrimau (less than 30 projections in P . tristanensis ); vi) gnathopod 2: basis with 1 triangular projection anterodistally in both P . telukrimau and P . tristanensis ; ischium with 1 large trapezoid projection in P . telukrimau (ischium with 1 triangular projection in P . tristanensis ); propodus width about half its length. Local distribution. Pulau Tinggi, Pulau Pemanggil, Pulau Sibu, Pulau Harimau, Pulau Rawa, Pulau Tengah, Pulau Hujung, Pulau Besar. Distribution. Currently only known from Johor , Malaysia .