Crustacea: Amphipoda: Epimeriidae

JOURNAL OF NATURAL HISTORY, 1994, 28, 555-576

A new Epimerin species (Crustacea: Amphipoda: Epimeriidae) and redescriptions of three other species in the genus from the Antarctic Ocean

c. O. COLEMAN Morphologie und Systematik der Tiere, Fakultiit [fir Biologie, Universitat Bielefeld, Postfach 1OO]]1, D-33501 Bidefdd, Germany (Accepted 26 April 1993)

The new species Epimeria annabeliae (Crust;u.:l:a: Amphipoda: Epimeriidae) from the Antarctic Ocean is described. Additionally, Hxkscriplions of the closely related E. monodon, E. robusra and E. puncticulara are given. KEYWORDS: Amphipoda, Crustacea, Epimeriidac, taxonomy, Antan:tica, Epimeria annabeliae n. sp.

Introduction Species of thc genus Epimeria are one of the conspicuous groups of Antarctic amphipods. Most of them are easy to distinguish due to characteristic dorsal outgrowths of the body. However, a rather small number of Antarctic species of this genus havc a smooth pereon, which makes identification more difficuil. Moreover most of these species are only very briefly described (K. H. Barnard, 1930, 1932), The following redeseriptions help to discriminate Ihese species. During this taxonomic work Epimeria annahellae n. sp. was discovered, a further epimeriid with smooth pcrconitcs. Systematics

Epimeria annabellae n. sp. (Figs 1-4) Material examined. HOLOTYPE ';> 18 mm. Locus typicus: 72°30·35'S, 17°29,88'W, depth 240-254m, USNM 239491, by Agassiz-traw1. Additional material. One mature ';>,20 mm; I mature';> , 19 mm, USNM 239492, 72°31·64 'S, Ir34·97'W, depth 242-264 m, collected during the Polarsfern cruise ANT Ill, 1985, by Agassiz-trawl. Etymology. The species is dedicated to thc author's daughter, who was born during the preparation of thcsc drawings. Diagnosis. Head with large oval eyes (Fig. IC). Third metasomal segmcnt with mid~dorsal keel. drawn out into a posterior process. First urosomite with pointed toolh (Fig. lA, C). Coxa of pereopod I slightly concave anteriorly (Fig. 2A). Propodus of gnathopods 1-2 slightly expanded distaJly, palm oblique, serrate (Fig 2A, F). Coxa of pereopods 2 and 3 convex anteriorly and excavate posteriorly (Figs 2F and 3A), Coxa of pereopods 1-3 acuminate. Coxa of pereopod 4 largest, overlapping preceding coxal plates, posterodistal angle drawn Qui and directing ventrally (Figs IC and 3D), and ()(J22-2~33N4 $[0·00 'J:; 1~4

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ho]otype. female, 18 mm. CA) Dorsal habitus:

(H) mandible: (C) lateral habitus: (D) mandibular palp: (E) maxilla 2, dotted line indicates length of setae: (r) labrum: (G) hypopharynx (lower lip): (H) detail of

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Antarctic Epimeriidae

FIG. 2.

557

Epimeria annabellae n. ~p., holotype. female, J Rmm. (A) Pereopod I: (B) antenna 1; (C) peduncle of antenna 2: (Dj peduncle of antenna I; (E) antenna 2; (F) pcrcopod 2; (G) maxilliped. right palp and endites omitted.

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FIG. 4. Epimeria annabellae n. sp.. holotypc, female, 18mm. (A) Pereopod 6; (8) carpus to dactylus of pereopod 6; (C) uropod 3; (I» left coxa of pcrcopod 7; (E) uropod 2; (F) uropod I; (G) carpus to daclylus of pcn:opod 7; CH) pereopod 7, (;oxa slighlly damagcd; (I) tclSOIl.

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curved medially below the ventral side. Pcrcopod 5 basis posterior margin somewhat sinuous (Fig. 3C). Basis of pereopod 6 slender, basis of pereopod 7 widened with distal pointed process (Fig. 4A. H).

Epimeria robw>'Ia K. H. Bamard. 1930

(Figs 5-8) Epim~ria

robusw K.. H. Barnard. 1930, p. 375, 449. figs 4Oa. 51: J. L Barnard. 1958. p. 108; J. L. Bamard. 1961. p. 103; key; McCain, 1971. p. 161: De Broyer and Klagcs, 1991. p. 164, key

Material examined. Rcdcscribed individual: ovig. 9. 40mm. 72°35.67'5, 18°g·17'W. depth 604-656 m. collccted during the Polar:Slein cruise ANT Ill. 1985 by Agassiz-trawl. Additio/lal malcrial. (A) Type material (BMNH 1930.8.1.303-309) from the British Antarctic Terra Nuva Expedition, 1910; (B) 2~~, 39 and 45mm (the larger with sctosc ooslegites); 61°19·7'5, 56°33·5'W (close to Elephant Is., South Shetland Is.). depth 404 m, collected during the RV Polarslern cruise ANT Vl/2 1987 by means of a fishery bottom trawl. Diagnosis. Body (Fig. 5A, B) robust. Posterior margin of pereonites 5-6 with small medial protrusion, pcreonitc 7 with shallow keel, pcreonite 7 and posterior margins of mctasome segments 1-2 with tOOlh-like elevation (in lateral view). metasome segmenlS 1-3 with mid-dorsal keel, metasome segment 3 and urosomite L with pointed toolh. urosomite 3 with shallow mid-dorsal keel. Hypopharynx (lower lip): as for Epimeria amwbellae n. sp. Coxa of pcrcopods 1-3 tapering distally. apically rounded (Figs 7A. B. E). Propodus of gnathopods 1-2 expanded distally. with well-developed palm. Coxa of pereopod 4 very large. with wide posterovenlral angle projecting somewhat ventrally. Pereopod 5 (Fig. 80, G) basis with posleromarginal tooth, basis of pereopod 6 with similar tooth bUI larger, pcreopod 7 basis (Fig. SC) widened proximally. but without tooth. only posterodistul angle pointed. Di.firibulion. Ross Sea, Weddell Sea. 82-547 m. Remarb. There seems to be some variability of the dorsal annature in this species. In the type material the keel of the metasomal segments is only well developed on segment 3, but very weak and rounded on segments 1-2, and the posterior margin of metasomal segments 1 is drawn out to a tooth. Also the teeth on metasoll1e segmenl 3 and urosomite I are rather short (Fig. 5e) compared with the redescribcd material (Fig. 5A). A tooth is also lacking on the posterior margin of metasome segment I of a specimen collected close to Elephant Is. (material B) (Fig. 5D).

t.pimeria mOlwdoll Stephensen. 1947 (Figs 9-12) Epimeria mo/Uxlon Sfcphensen. 1947, p. 53. fig. 19; J. L. Bamard, 1958. p. 108; J. L. Barnard. 1961. p. 103. key: MeCain. 1971. p. 16t. table I: Thurston. 1974a, p. 34; Thurston, 1974b. p. 66: De Broycr and Klages. 1991, p. 164. key.

Material examined. Described individual: I ovig. 9. 25 mm (BMNH 1969;250:8). Rcdfearn collection, Inll964, St 59. Elephant Rats, Signy Is., South Orkney Is., detcnnined by M. H. Thurston.


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FIG. 5. Epimeria robusra, female, 40 mm (A) Lateral habitus; (8) dorsal habitus; (C) metasome and urosome or type material; (D) metasome and urosome of a specimen from Elephant Is. (South Shetland Is.); (E) labrum; (F) mandibular palp; (G) mandibular body.

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FIG. 6. Epim~ri(l robUSIa, female. 40mm (A) Maxilla I; (8) frontal face of inner maxillipedal endite: (C) maxilliped. left palp and cnditcs omitted: (D) shape of maxilla 2: (E) delails of maxilla 2; (F) antenna 2; (G) antenna J.


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FIG. 8. Epimeria robusta. female. 40mm. (A) Pereopod 6; (B) Iclson: (C) pereopod 7; (0) pcreopod 5. coxa dissec::tcd; (E) lIropod I: (F) uropod 2; (G)

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Epimeria pUlleticu/nfa, type, 12mm female. (A) Pereopod 6; (C) uropod I; (I» uropod 2; (E) uropod 3; (F) pereopod 7.

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Table I. Character

Comparison of the Epimeria

~pct:ics

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E. wmabe/lae ll. sp.

E. robll.l'UI

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normal

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Posterior mid-dorsal teeth on pcreonites

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Urosomal teeth

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only hump

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concave antcriorly. concave posteriorly

convelt anteriorly. concave posleriorly

pantile! margins

sUbtrinngulnr

convex anteriorly. concave posteriorly

Gnathopodal propodi

expanded dislally

eXp3nded distul1y

wClIklyeltpllndcd dislally

slender, not exp.1llded

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