Erikus lovrichi, Alonso, 2012

Alonso, G. M., 2012, Amphipod crustaceans (Corophiidea and Gammaridea) associated with holdfasts of Macrocystis pyrifera from the Beagle Channel (Argentina) and additional records from the Southwestern Atlantic, Journal of Natural History 46 (29 - 30), pp. 1799-1894 : 1843-1853

Erikus lovrichi sp. nov.

( Figures 17–22 )

Type material

Argentina; Beagle Channel, northern Isla Despard , 54 ◦ 52 ′ S, 68 ◦ 10 ′ W, 8–12 m depth, colls. D. Aureliano and A. Ferlito, don. G. Lovrich: HOLOTYPE, ovig. ♀ 15.5 mm, 24 May 1999, MACN-In 38623a. PARATYPES, 1 ♂ 13 mm, 29 May 2000, MACN-In 38624a. Same location, same colls., 19 March 1999: 1 ♀ 9.75 mm, MACN-In38625a; 16 ovig. ♀♀ 11–13.8 mm, 19 ♀♀ 10.3–14 mm, MACN-In 38625b; 2 ♂♂ 11.8 and 11.9 mm, MACN-In 38625c. Same location, same colls., 24 May 1999: 8 ovig. ♀♀ 12–14 mm, 5 ♀♀ 10.3–13 mm, MACN-In 38623b; 3 ♂♂ 12–13 mm, MACN-In 38623c; 2 ♀♀ 9.9 and 11 mm, 1 sex indet. 4.2 mm, MACN-In 38623d; 5 ovig. ♀♀ 13–15 mm, 16 ♀♀ 11–16 mm, MACN-In 38623e; 4 ♂♂ 12–13.7 mm, MACN-In 38623f; 19 ovig. ♀♀ 12–15.5 mm, 6 ♀♀ 13.8–15 mm, MACN-In 38623g; 3 ♂♂ 13–14 mm, MACN-In 38623h. Same location, same colls., 27 May 1999: 4 ♀♀ 8–11.7 mm, MACN-In 38626a; 1 ovig. ♀ 13 mm, 10 ♀♀ 10–13 mm, 5 sex indet. 3.3–7 mm, MACN-In 38626b; 2 sex indet. 4 and 6.75 mm, MACN-In 38626c. Same location, same colls., 5 August 1999: 3 ovig. ♀♀ 11 mm, 2 ♀♀ 9 and 13 mm, 7 sex indet. 4.5–9 mm, MACN-In 38627a; 1 ♀ 11 mm, MACN-In 38627b; 1 ♂ 12 mm, MACN-In 38627c; 1 ovig. ♀ 12 mm, 2 ♀♀ 13 mm, MACN-In 38627d; 12 ovig. ♀♀ 9.8–14 mm, 3 ♀♀ 12–14 mm, 10 sex indet. 6–11 mm, MACN-In 38627e. Same location, same colls., 11 August 1999: 8 ovig. ♀♀ 11–12.3 mm, MACN-In 38628a; 1 ♂ 10.5 mm, MACN-In 38628b; 1 ♀ 9.2 mm, MACN-In 38628c; 1 sex indet. 7.2 mm, MACN-In 38628d; 1 ♀ 9.5 mm, MACN-In 38628e; 1 ovig. ♀ 9 mm, MACN-In 38628f; 1 ovig. ♀ 12 mm, 2 ♀♀ 10 and 11.5 mm, 5 sex indet. 3–11 mm, 1 November 1999, MACN-In 38629. Same location, same colls., 10 November 1999: 1 ♀ 8 mm, MACN-In 38630a; 1 ♀ 7.7 mm, MACN-In 38630b; 5 ovig. ♀♀ 12–15 mm, MACN-In 38630c; 2 ovig. ♀♀ 13.9 and 14 mm, 4 ♀♀ 6.9–7 mm, 2 sex indet. 3.9 and 4.3 mm, MACN-In 38630d. Same location, same colls., 10 February 2000: 3 sex indet. 7–7.05 mm, MACN-In 38631a; 1 sex indet. 5.2 mm, MACN-In 38631b; 2 ♀♀ 12 and 12.8 mm, 2 sex indet. 10 and 10.4 mm, MACN-In 38631c; 1 ♂ 11 mm, MACN-In 38631d; 1 ovig. ♀ 11.1 mm, 7 ♀♀ 6.6–10 mm, 8 sex indet. 4–9 mm, MACN-In 38631e; 2 ovig. ♀♀ 13 mm, 7 ♀♀ 10–12.3 mm, MACN-In 38631f; 2 ♂♂ 11 and 12 mm, MACN-In 38631g; 1 ovig. ♀ 12.15 mm, 5 ♀♀ 8.5–12 mm, 8 sex indet. 4–11 mm, MACN-In 38631h; 1 ♀ 9.5 mm, 1 sex indet. 12 mm, 14 February 2000, MACN-In 38632. Same location, same colls., 2 May 2000: 4 ovig. ♀♀ 12–13 mm, 4 ♀♀ 11–12 mm, MACN-In 38633a; 2 ovig. ♀♀ 13 mm, 2 ♀♀ 10 mm, MACN-In 38633b; 1 sex indet. 4.5 mm, MACN-In 38633c; 2 ovig. ♀♀ 12.1 and 14 mm, 5 ♀♀ 9.5–12 mm, 8 sex indet. 4–10.6 mm, MACN-In 38633d; 6 ovig. ♀♀ 12–14 mm, 5 ♀♀ 12–13.2 mm, MACN- In 38633e; 1 ♂ 12 mm, MACN-In 38633f. Same location, same colls., 29 May 2000: 8 ovig. ♀♀ 13–15 mm, 30 ♀♀ 11–15 mm, MACN-In 38624b; 5 ♂♂ 10–14 mm, MACN- In 38624c; 6 ovig. ♀♀ 13–14.5 mm, 19 ♀♀ 11–14.7 mm, MACN-In 38624d; 1 ♂ 11 mm, MACN-In 38624e; 8 ovig. ♀♀ 13–16 mm, 10 ♀♀ 11–15 mm, MACN-In 38624f; 3 ♂♂ 12–13 mm, MACN-In 38624g; 7 ovig. ♀♀ 11–15.2 mm, 11 ♀♀ 10–14.8 mm, MACN- In 38624h; 3 ♂♂ 12–13.5 mm, MACN-In 38624i; 2 ovig. ♀♀ 13 and 13.5 mm, 7 ♀♀ 8.8–14.4 mm, 14 sex indet. 3.5–11 mm, MACN-In 38624j .

Material examined

See Type material specified above.

Diagnosis

Head deeper than long; lateral cephalic lobes rounded; anterior margin with deep notch. Eyes large, reniform. Female A1 longer than A2; peduncular article 1 elongate, with nine lateral and nine posterior penicillate setae in females, and eight lateral and seven posterior penicillate setae in males; primary flagellum with calceoli every two articles. Male A2: with brush setae on peduncular articles 3–5. Mandibular palp, article 2 with six to seven posterodistal setae in females, and 15 to 18 in males; article 3 with 12 to 14 in females and 15 to 16 in males. Gn1: propodus bearing two rows of setae on distal half, anterior margin with four rows and posterior margin lined with very short fine setae and seven groups of long setae. Male P3 and P4: posterior margins of merus and carpus strongly setose. P6 and P7: basis crenellate posteriorly. Ep3: with notch on posterior margin above rounded posteroventral corner. U3: rami scarcely setose in females and densely setose in males.

Description

Holotype ovigerous female: body length 15.5 mm. Head about as long as first peraeonite, much wider than long; lateral cephalic lobes rounded; anterior margin with notch extending into slit at level of attachment of A2; rostrum absent. Eyes large, reniform, dark brown in alcohol.

A1: Longer than A2; peduncular article 1 elongate, 1.8 times as long as wide with nine lateral and nine posterior penicillate setae, posterodistal corner produced bearing one penicillate seta and one small seta, distal margin with four setae, two medial setae longest; article 2 0.4 times as long as article 1, with distal setae; peduncular article 3 0.7 times as long as article 2, distal margin straight bearing setae close to posterior angle; primary flagellum with at least 43 articles (broken), articles bearing short setae and long aesthetascs; accessory flagellum 11-articulate.

A2: Peduncular article 4 2.4 times as long as broad, 1.7 times as long as article 5, with setae on anterior and posterior margins; article 5 2.1 times as long as wide, bearing setae on anterior margin and on anterior and posterior corners; flagellum 33-articulate.

Mouthpart bundle subconical.

UL and epistome fused, in lateral view produced into broad step.

Md: Incisors smooth; right lacinia mobilis absent, left broad, distally toothed; accessory setal row well developed, with about 17–18 robust setae, bearing distal tuft of setae and numerous intermediate simple setae; molar tongue-like, with margins setose; palp three-articulate, article 2 1.5 times as long as article 3, bearing seven and six posterodistal setae on right and left mandibles respectively, article 3 bearing 14 posterior and five apical setae on right side, anteroproximal margin smooth (socket not seen), with 12 posterior, five apical and one anteroproximal seta on left side.

LL: Without inner lobes, with large, setose outer lobes and long mandibular processes.

Mx1: Without palp; inner plate broad bearing two apical plumose setae of different length; outer plate with 11 terminal setal teeth arranged into two rows, one row of seven setal teeth large and long, and a row of four setal teeth shorter.

Mx2: Plates slender, inner plate slightly shorter than outer, bearing about 12 medial, nine intermediate and nine lateral setae.

Mxp: Inner plate subrectangular, distal margin irregular, setose, with oblique setal row of 10 plumose setae; outer plate large, subovate, naked; palp four-articulate, article 2 slightly longer than article 3, both articles posteriorly setose, article 3 with anterior margin bearing groups of subapical and apical setae; article 4 reduced, with two elongate setae on apex.

Gn1: Simple; coxa small, subquadrate; basis elongate, almost as long as ischium, merus and carpus combined, with posterior and anterior margins setose; ischium about as long as merus and carpus combined, with setae on posterior margin; merus posteriorly setose; carpus slightly shorter than propodus, posteriorly setose; propodus subrectangular, narrowing distally, medial surface with two setal rows on distal half, anterior margin bearing four setal rows, posterior margin lined with very short, fine setae and seven groups of long setae; dactylus bearing minute setae along posterior margin.

Gn2: Subchelate; coxa almost twice length of coxa 1; basis slender, elongate; ischium 0.4 times as long as basis; carpus 1.8 times as long as propodus, both articles with posterior margin densely setose; propodus subrectangular, palm oblique, with minutely denticulate surface, bearing about nine marginal and 11 subterminal small setae, one stout medial robust seta and one large pectinate seta guarding palm; dactylus reaching stout medial robust seta.

P3: Coxa subrectangular, 1.4 times length of coxa 2, posteroventral corner with notches each bearing one minute seta; basis 0.6 times length of coxa; merus weakly expanded anteriorly, 0.8 times as long as basis; carpus narrow, 0.7 times as long as merus, both articles with posterior margin bearing few medium setae; propodus slightly longer than carpus, somewhat broader distally, with short robust setae posteriorly; dactylus elongate.

P4: Coxa large, subquadrate, 1.2 times as long as wide, posteriorly excavated, posteroventral corner produced, with tip rounded; remaining articles as in P3.

P5: Coxa 1.4 times as long as wide, somewhat expanded posteriorly; basis subrounded, almost broader than long, expanded posteriorly, posterior margin slightly crenellate, anterior margin rounded; merus expanded posteriorly, anterior and posterior margins with short robust setae; carpus 0.7 times as long as merus, anterior margin and posterodistal corner with robust setae; propodus 1.4 times as long as carpus, anterior margin and anterodistal corner with robust setae; propodus and dactylus as in P3 and P4.

P6: Coxa 1.3 times as long as wide; basis subovate, 1.1 times as long as wide, posterior margin convex, crenellate, anterior margin rounded; remaining articles as in P5, but slightly longer.

P7: Coxa small, rounded; basis 1.2 times as long as wide, posterior margin evenly convex, crenellate, anterior margin almost straight; remaining articles as in P6.

Gills large, attached to coxae 2–7. Oostegites on coxae 2–5.

Pl1–Pl3: Subequal in length. Pl1: peduncle with two locking spines; outer ramus with 23 articles, inner with 19. Ep3: posterior margin smooth, convex, with notch above rounded posteroventral corner.

U1–U3: With terminal unguis. U1: peduncle slightly longer than rami, dorsolateral margin with 12 robust setae and one apicolateral robust seta, dorsomedial margin with five robust setae and one apicomedial robust seta; inner ramus slightly longer than outer, with four medial and six lateral robust setae; outer ramus bearing eight lateral robust setae.

U2: Peduncle somewhat shorter than outer ramus, dorsolateral margin with two and one apicolateral robust seta, dorsomedial margin bearing two robust setae and one apicomedial seta; outer ramus 0.8 times as long as inner, with row of six dorsolateral robust setae; inner ramus incised, with two dorsolateral and three dorsomedial robust setae, incision bearing one longer robust seta.

U3: Peduncle 0.6 times as long as rami, with one dorsomedial proximal simple seta, six dorsomedial robust setae and one dorsolateral robust seta apically; rami lanceolate, subequal in length, with few plumose setae along medial margins; outer ramus two-articulate, article 1 with lateral margin bearing seven robust setae and dorsomedial margin with three, each side of apex with two small simple setae, article 2 reduced, rectangular-shape; inner ramus, dorsomedial margin with one proximal seta and eight robust setae inserted in notches, dorsolateral margin bearing three robust setae.

T: Elongate, enlarged proximally, 1.7 times as long as wide, cleft 0.6 of its length, each lobe with two midlateral penicillate setae, apices truncate, strongly irregular, each bearing one penicillate seta and one shorter seta.

Additional observations

Paratype male: body length 13 mm. Eyes larger than in holotype.

A1: Peduncular article 1 shorter and broader than in holotype female, with about eight lateral and seven posterior penicillate setae; article 3 with medial excavation; primary flagellum with at least 50 articles (broken), first article with two-field callynophore well developed, calceoli present on articles 5, 7... 31, 32, 34... 42, 43 and 45; accessory flagellum bearing nine articles.

A2: Peduncular articles 3–5 bearing brush setae; flagellum with 60 articles, bearing 54 calceoli from articles 1 to 54.

Md: Accessory setal row with about 14 robust setae; right and left palp articles 2 bearing 18 and 15 posterodistal setae respectively, right and left palp articles 3 with 15 and 16 posterior setae, five apical setae and two anteroproximal setae on both sides.

P3 and P4: Posterior margins of merus and carpus strongly setose.

U3: Medial margins of rami densely setose.

Etymology

Named for Gustavo Lovrich, marine biologist at the CADIC, in appreciation for providing all the kelp holdfast specimens.

Remarks

Erikus lovrichi is closely related to Erikus dahli Lowry and Stoddart, 1987 , which is the only species of the genus described from southern Chile, South America. They are similar in general body appearance: including head, gnathopods, peraeopods, uropods and third epimeron. However, both species differ in the following morphological characters: in E. lovrichi the peduncular article of the first antenna is longer in females, and the number of lateral and posterior penicillate setae differs between females and males; the male primary flagellum is composed of a large number of articles (at least 50 versus 36 articles), so bearing a large number of calceoli, which are located every two articles, beginning at article 5 (versus calceoli present on articles 3–29). In E. lovrichi the female second antenna is shorter than the first one; brush setae are present on the male peduncular articles 3–5 instead of being on articles 4 and 5. The accessory setal row of the mandibles has 14 robust setae instead of 11 as in the male; the number of posterior setae on the palp articles 2 and 3 is different in both species; in the new species the lacinia mobilis seems to be more cuspidate. In E. lovrichi , the inner lobe of the maxilliped has an oblique setal row with a smaller number of plumose setae and the outer plate is naked. Although the shape of the first gnathopod is very similar in both species, the propodus of E. lovrichi differs in the number of rows and groups of setae along the medial and posterior margins. The coxae of the sixth and seventh peraeopods are somewhat different in shape, and in E. lovrichi the basis bears more prominent posterior marginal notches. Erikus lovrichi and E. dahli show variations in the number of robust setae on the peduncle and rami of the first and second uropods, and the outer ramus of the first uropod is shorter in the new species. Both species also differ in the number of robust setae on the third uropod, which is remarkably less setose in the holotype than in the Chilean species.

The new species may reach sexual maturity at a smaller size, as suggested by comparing the size ranges of mature individuals of E. lovrichi and E. dahli .

Lowry and Stoddart (1987) stated that males of Erikus lack an elongate second antenna flagellum and, accordingly, they preclude this feature as a male secondary sexual character in their diagnosis of the genus. However, in the specimens from Argentina the second antenna flagellum is considerably longer in mature males than in females. Lowry and Stoddart (1987) noted that the South African species Amaryllis macrophthalma Haswell, 1879a as described by Stebbing (1908), had an elongate male second antenna among many attributes proper to Erikus ; on this basis, this feature would not exclude Stebbing’s species from Erikus , because the elongate male second antenna is considered to be a plesiomorphic character.

The new species recorded in the Beagle Channel, is assigned to the South American Erikus taxon because it possesses all the character states diagnosed by Lowry and Stoddart (1987) for both males and females of the genus.

Family ENDEVOURIDAE Lowry and Stoddart, 1997

Figures

Figure 17. Erikus lovrichi sp. nov. Holotype, ovigerous female: (A) antenna 1; (B) antenna 1 peduncle; (C) antenna 1 peduncle article 1; (D) antenna 2; (E) epistome; (F) right mandible; (G) left lacinia mobilis; (H) right setal row; (I, J) right and left mandibular palp. Scale bars: a: (A, D) 0.5 mm; b: (B), e: (F) 0.2 mm; c: (C), d: (E, G–J) 0.1 mm.

Figure 18. Erikus lovrichi sp. nov. Holotype, ovigerous female:(A) maxilla 1; (B) maxilla 1 outer plate, (C) maxilla 2; (D–F) maxilla 1 medial, intermediate and lateral setae; (G) maxilliped: (H) maxilliped inner plate; (I) gnathopod 1; (J, K) gnathopod 1 propodus and dactylus. Scale bars: a: (A, C, G, J) 0.2 mm; b: (B, D–F, H, K) 0.1 mm; c: (I) 0.5 mm.

Figure 19. Erikus lovrichi sp. nov. Holotype, ovigerous female: (A) gnathopod 2; (B, C) gnathopod 2 palms; (D) peraeopod 3; (E) peraeopod 3 coxa ventrodistal margin; (F) peraeopod 3 dactyluds; (G–J) peraeopods 4–7. Scale bars: a: (A, D, G–J) 0.5 mm; b: (B, C) 0.1 mm; c: (E, F) 0.2 mm.

Figure 20. Erikus lovrichi sp. nov. Holotype, ovigerous female: (A) pleopod 1; (B) pleopod 1 locking spines; (C) epimeron 3; (D–F) uropods 1–3; (G) uropod 3 article 2; (H) telson; (I) telson apex. Scale bars: a: (A, C) 0.5 mm; b: (B, G, I) 0.1 mm; c: (D, E, H), d: (F) 0.2 mm.

Figure 21. Erikus lovrichi sp. nov. Paratype, male 13 mm: (A) lateral view; (B) antenna 1; (C) callynophore; (D) antenna 2; (E) antenna 2 peduncle. Scale bars: a: (A) 3 mm; b: (B, D) 0.5 mm; c: (C), d: (E) 0.2 mm.

Figure 22. Erikus lovrichi sp. nov. Paratype, male 13 mm: (A) left mandibular palp; (B, C) peraeopods 3, 4; (D) uropod 3. Scale bars: a: (A) 0.1 mm; b: (B, C) 0.5 mm; c: (D) 0.2 mm.