Lepechinella norvegica, Johansen, Per-Otto & Vader, Wim, 2015

Johansen, Per-Otto & Vader, Wim, 2015, New and little known species of Lepechinella (Crustacea, Amphipoda, Lepechinellidae) and an allied new genus Lepesubchela from the North Atlantic, European Journal of Taxonomy 127, pp. 1-35 : 10-18

Lepechinella norvegica sp. nov.

urn:lsid:zoobank.org:act:F3E97726-1656-45CF-BD00-98A19A172FD0

Figs 5–9

Diagnosis

Eyes absent. Body heavily covered with spines and setae. Rostrum longer than lateral processes. Mandible palp article 1 subequal to article 3. Molar oval with ragged margins. Maxilliped palp 4-articulate. Posterior legs long and very slender. Coxal plate 4 symmetrically bifid. Posterodistal corner of coxa 7 rounded. Gills smooth. Pleon segments 1–3 each with one small and one large dorsal tooth. Telson deeply cleft.

Etymology

norvegica (Latin) = Norwegian.

Material examined

The holotype of Lepechinella norvegica sp. nov. was collected during the Mareano project using RPsledge at station R-578, situated at Teistengrunnen on the Norwegian coast. The sediment at R-578 consisted of sandy mud with gravel. Additional material examined was collected from the Mareano-

station R-11, Tromsøflaket and from station 1136-79, Bleikdypet. The type material of Lepechinella sp. nov. is deposited in the collections of Bergen Zoological Museum and Tromsø Museum in Norway.

Holotype

♂, registration no. ZMBN 99130 , station R-578, 70 o 22.66’N, 17 o 10.14’E, depth 706 meter, 9 Aug. 2010 ( Figs 5–8 ).

Allotype

♀, registration no. ZMBN 99131 , station R-578, position and date as for holotype ( Fig. 9 ).

Additional material

♂, registration no. ZMBN 99132, station R-578, position and date as for holotype.

♀, registration no. ZMBN 99133, station R- 11, 301 meter, 71 o 13.22’N, 21 o 43.41’E, 1 Jun. 2006.

♂, registration no. TSZCr 14984, station 1136- 79, 69 o 27’N, 15 o 20’E, depth 720–750 meter, 21 Aug. 1979.

Description

Holotype

Adult male 7 mm.

BODY. Abundantly covered dorsally and laterally with long setae and spines. Spines, which vary in length, are attached to discs. Coxal plates posteriorly decreasing in height. 2 mid-dorsal teeth on peraeon segment 1 and one on each peraeon segments 2–7. One small mid-dorsal wart with 2 setae prior to the tooth on peraeon segment 7. Pleon segments 1–3, each with 1 small and 1 large dorsal tooth. Gnathopods 1–2 shorter than peraeopod 3–7.

HEAD. Rostrum acute and 0.5x antenna 1 peduncle article 1; rostrum 2x eye lobes; postantennal corner with rounded angle; eyes absent or at least indistinct in alcohol; setae on the head attached to cylindershaped pegs. Row of short setae-groups on posterior margin of antenna 1 peduncle articles 1–2; peduncle article 1 broader than peduncle articles 2–3; peduncle article 2 medially tapering and 2x peduncle article 1; peduncle article 3 is 1/3 of peduncle article 1; flagellum with at least 26 articles (the tip is broken); flagellum 1.4x peduncle articles 1–3 combined; accessory flagellum is 1-articulate with two apical setae. Antenna 2 longer than antenna 1; antenna 2 peduncle articles 4–5 anterior margin with row of setae groups distally decreasing in length; peduncle articles 1, 2 and 3 broader than peduncle articles 4 and 5; peduncle article 4 distally tapering; peduncle article 5 is 2x peduncle article 4; flagellum longer than peduncle article 5; flagellum 33-articulate.

MOUTHPARTS. Upper lip oval lobes and medially constricted; lower lip bilobate; inner lobe extending to 1/2 of the outer lobe. Mandible, incisor and lacinia mobilis of subequal length, both with denticles; molar is elliptic, saucer-shaped with ragged margins; 6–7 accessory spines; mandible palp article 1 and 3 subequal; mandible article 2 slightly curved with 12 long setae; mandible article 2 is 4x article 3, mandible article 3 with 4 lateral and 4 long apical setae. Maxilla 1, inner plate narrow with 2 apical plumose setae; outer plate tapering distally, with 10 apical serrate spine teeth; palp 2-articulate obliquely truncated; palp with 6–7 blunt spines and one longer apical spine. Maxilla 2, inner plate shorter and narrower than outer plate; outer plate with about 25 distal long setae; inner plate with 1 strong plumose setae in addition to apical setae; inner margin of inner plate lined with setae. Maxilliped, outer plate 2x inner plate; inner plate slender with 3 blunt apical teeth and setae along the inner margin; outer plate armed with 14 broad spine teeth of decreasing length on distal and medial margin; outer plate reaches article 3 of palp; palp 4-articulate where the second article is subequal to the two last articles combined.

PERAEON. Coxal plate 1, 3 and 4 biacuminate, coxae partly covered with setae and spines attached on

disc-shaped pegs. Gills, shape oval and smooth. Gnathopod 1 subchelate; coxal plate 1 asymmetrically

bifid with long setae along distal margins; anterior coxal plate 1 process 1.4x posterior process; propodus shorter than carpus and distally tapering; posterior margin of carpus with 7 groups of long setae; dactyl curved with 6 notches; dactyl 0.5x propodus; both margins of propodus with 4 groups of setae; palm of propodus serrulate. Gnathopod 2 longer than gnathopod 1. Coxal plate 2 tapering to an acute tip; gnathopod 2, merus 1/3 of carpus; carpus 1.4x propodus; dactyl curved with 7 notches; palm of propodus serrulate. Coxal plate 3 asymmetrical, anterior part pointed, posterior part with a small hump; peraeopod 3, merus 1.6x carpus; propodus and dactyl subequal; dactyl lanceolate. Coxal plate 4 symmetrically

bifid; peraeopod 4, merus 1.6x carpus; carpus 0.7x propodus and dactyl; short spines and setae on coxal plate 4 and basis. Coxal plate 5 anteriorly acute, posterior part rounded; peraeopod 5, merus 0.6x carpus; carpus 1.3x propodus; dactyl lanceolate; dactyl shorter than propodus. Coxal plate 6 anteriorly bluntly pointed; peraeopod 6, merus subequal to propodus; merus 0.7x carpus; small spines and setae on coxal plate 6 and basis; dactyl shorter than propodus; dactyl lanceolate. Coxal plate 7 anterior part acute and posterior rounded; coxal plate 7 is 2x broader than high; peraeopod 7, merus 0.6x carpus; carpus 1.3x propodus.

PLEON. Segments 1, 2 and 3 each with one large and one small dorsally situated tooth. Posterodistal angle of epimeral plates 1–3 acute, forming a small sinus; epimeral plate 3 sinus largest; setae along margins and 2 arrays of spines on epimeral plates 1–3. Urosome segment 1 subequal to 2 and 3 combined; urosome segment 1 with 1 mid-dorsal tooth; urosome segments 2 and 3 fused. Uropod 1 peduncle has two distal spines and rows of spines along the margins; peduncle longer than both rami; inner ramus 0.9x outer. Uropod 2 peduncle shorter than inner ramus and subequal to outer; outer ramus 0.8x of inner ramus. Uropod 3 peduncle about 1/5 of the rami; longer ramus 1.1x shorter; rami densely covered with long setae. Telson parts are gaping, cleft to 80 % of total length; length of apical setae subequal to telson; four setae along the margins of telson, four spines on the dorsal part of the last urosome segment.

Allotype

Adult female 7 mm.

Antenna 1 peduncle article 1 is 1.5x article 3; scattered long setae along margins of peduncle article 2; peduncle article 2 is 2.5x peduncle article 1; peduncle article 1 broader than peduncle articles 2–3; flagellum 24-articulate; flagellum 1.5x peduncle articles 1–3 combined; accessory flagellum is 1-articulate with two apical setae. Antenna 2 length subequal to antenna 1; antenna 2 peduncle articles 3–5 margins with groups of setae decreasing in size distally; peduncle articles 2–3 broader than peduncle articles 4–5; peduncle articles 5 is 1.5x peduncle article 4; flagellum subequal to peduncle article 5; flagellum 18-articulate. Gills oval and smooth. Uropod 3, peduncle 1/6 of longer ramus; shorter ramus 0.9x longer, rami with long setae along the margins; posteriodistal angle of epimeral plates 1–3 acute, forming a sinus; sinus largest in epimeral plates 2 and 3; setae and spines on epimeral plates 1, 2 and 3.

Variation

The rostrum is about 30 % of the length of antenna 1 peduncle article 1 in 2 mm long specimens while it is about 50 % in 7 mm long specimens. The dorsal teeth of coxal plate 1 are about 50 % of the body height of peraeon segment 1 in 6–7 mm long specimens, but only 20 % in 2 mm long specimens. Large specimens have one small dorsal wart armed with two setae prior to the large posterior tooth of peraeon segment 7. Males have large teeth that are pointing backwards, while females have more slender and upright teeth on pleon. Female antenna 1 and 2 peduncle margins have scattered long setae, while males have dense rows of small setae. Antenna 2 is longer than antenna 1 in males, while they are subequal in females and antenna 2 peduncle article 5 is 2x the penultimate peduncle article in males, while it is 1.5x in females. Posterodistal angle of epimeral plate 3 is situated more in centre in females than males, which results in a larger sinus in females. The setae on the rami of uropod 3 seem to be denser in males than in females. Sexual dimorphism has also been observed in dorsal armature, posterodistal shape of epimeral plates and setal armature of antennal peduncles of L. helgi , L. grimi and L. skarphedini ( Thurston 1980a) .

Remarks

L. norvegica sp. nov. from Northern Norway is characterized by a dense cover of long setae and spines. Spines with the longer setae are usually situated dorsally while spines on disc-shaped pegs are mainly situated laterally on the body, on the coxae and on the basis of the posterior legs. However, a lot of

the spines were probably broken, leaving only the disc to which they were attached. Setae attached to cylinder-shaped pegs were observed on the head. The postantennal corner of L. norvegica sp. nov. is rounded while L. arctica has an acute postantennal corner according to Schellenberg ( Table 1 ). Mandible palp article 1 and 3 of L. norvegica sp. nov. are subequal, while article 3 is larger in L. schellenbergi and L. arctica . The molar is elliptic with small marginal ribs in L. norvegica sp. nov. and has a certain similarity to the molar of Lepechinelloides kari Thurston, 1980 and Lepechinella turpis J.L. Barnard, 1967 . The width of maxilla 2 inner plate is about 1/3 of the outer in L. norvegica sp. nov., while it is about 1/ 2 in L. schellenbergi and L. arctica and 2/ 3 in L. victoriae sp. nov. L. norvegica sp. nov. has a symmetrical

bilobate coxal plate 4. Coxal plates 3 and 4 are 2x wider than basis of respective legs and thus the legs seems stouter than in the case of L. schellenbergi and L. arctica . Peraeopod 3 merus of L. norvegica sp. nov. is 1.6x carpus and merus subequal to basis. The merus/carpus ratio is higher in L. arctica and lower in L. schellenbergi . The inner edges of gnathopod 1–2 dactyls have notches resembling dactyls of many Liljeborgia species. The position and number of setae on the telson are different in L. norvegica sp. nov. and L. schellenbergi . The telson is more deeply cleft in L. norvegica sp. nov. (about 80 %) than

L. schellenbergi (about 50 %). Telson of L. grimi and L. skarphedini is about 60–65 % cleft, while it is about 40 % in L. helgi and L.victoriae sp. nov.

Figures

Fig. 5. Lepechinella norvegica sp. nov., holotype, ♂. A. Habitus. B. Left Gn1. C. Dactyl and propodus of Gn1. D. Right Gn2.

Fig. 6. Lepechinella norvegica sp. nov., holotype, ♂. A. Right Ep1. B. Spine on Ep1. C. Right Ep2.

Fig. 7. Lepechinella norvegica sp. nov., holotype, ♂. A. Right P4. B. Tooth of peraeon segment 4. C. Left P6. D. Spine on basis of P6. E. Male A2. F. Male A1. G. Accessory flagellum on A1

Fig. 8. Lepechinella norvegica sp. nov., holotype, ♂. A. Left U1. B. Left U2. C. U3. D. Telson. E. Upper lip. F. Lower lip. G–H. Left and right Mx1. I. Right Mx2. J–K. Left and right Mxp. L. Left mandible.

Fig. 9. Lepechinella norvegica sp. nov., allotype, ♀. A. A1. B. Accessory flagellum of A1. C. Female A2. D–E. Right and left mandible. F. Right Ep1. G. Left Ep2. H. Left Ep3. I. Spine on Ep 1. J. Telson and left U3. K. Gill of P3