Epimeria (Metepimeria) acanthurus
Creators: name: Coleman, Charles Oliver
name: Krapp-Schickel, Traudl
name: Häussermann, Vreni
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Epimeriidae
Epimeria
Epimeria acanthurus

description: Epimeria (Metepimeria) acanthurus (Schellenberg, 1931)
Figs 12–17, 30d
Metepimeria acanthurus Schellenberg, 1931: 162, fig. 85, pl. 1 fig. g.
Epimeria acanthurus – K.H. Barnard 1932: 176, figs 104b, 108, pl. 1: fig.
Metepimeria acanthurus – J.L. Barnard 1958: 108. — Lowry & Bullock 1976: 122. — Watling & Holman 1981: 216–217, fig. 22. — J.L. Barnard & Karaman 1991: 397. — Gonzalez 1991: 60. — De Broyer & Jażdżewski 1993: 36. — Lörz & Brandt 2004: 179–190 (phylogeny). — Coleman 2007: 61, fig. 36, map 1 (rhomb).
“ Epimeria inermis 1” – Rauschert & Arntz 2015: 61, pl. 54.
Epimeria (Metepimeria) acanthurus – d’Udekem d’Acoz & Verheye 2017: 117–118.
Material examined
CHILE • 1 ♀ (22 mm) with setose oostegites and slightly damaged mouthparts; Isla van der Meulen; -48.2901°, -74.33583333°; 15 m depth; 23 Apr. 2015; 250HF24; on hydrozoans, sponges, gorgonians and soft corals (e.g., Alcyonium haddoni Wright & Studer, 1889); colour: orange with white specks, especially on the tergites of the pereonites; ZMB 34099 (Figs 12–17) • 1 dissected ♀ (unspecified type material, with setose oostegites; Puerto Harris; 11 Mar. 1896; Museum Stockholm leg.; ZMB 22838.
Description (based on ♀ with setose oostegites, 22 mm).
BODY. Head (Fig. 12a, d) with slightly curved rostrum; eyes large and oval; frontal head margin weakly produced, ventral head margin straight. Pereonites 1–2 (Fig. 12a) slightly longer than pereonite 3. Pereonites 3–5 successively longer. Pereonite 5 with mid-dorsal rounded hump at posterior margin. Pereonites 6 and 7 dorsal outline sinuous and mid-dorsal rounded upright hump at posterior margin, that on pereonite 7 larger and slightly more curved posteriorly than that on 6; posterodorsolateral rounded hump on both sides. Pleonites (Fig. 12a) 1–3 progressively longer; pleonites 1–2 with similar dorsal outline as pereonite 7 and posterodorsolateral humps; pleonite 2 with additional hump anteriorly; pleonite 3 with 2 shallow dorsal depressions and mid-dorsal hump anterior of segmental end; posterior margins of pleonites sinuous; posteroventral corner of pleonite 1 angular, those of pleonites 2–3 pointed. Urosomite 1 longest, with mid-dorsal pointed process; urosomite 2 shortest; urosomite 3 with shallow lateral dorsal ridges.
HEAD APPENDAGES. Antenna 1 (Fig. 13d) peduncle stout, without long processes, peduncular articles length ratios: 1:0.4: 0.3; accessory flagellum uni-articulate, small, scale-like; flagellum 1 st article about as long as the next 3 articles, more than 11 articles (tip broken off) with groups of long setae and aesthetascs. Antenna 2 (Fig. 13c) peduncular articles 1–2 circumpass article 3; peduncular articles 4 and 5 subequal; flagellum 1 st article about as long as the next 3 articles, flagellum of more than 23 articles (tip broken off). Upper lip (labrum) (Fig. 12b) tapering distally with a shallow notch and fine setation on both sides of the notch. Mandible (Fig. 13a–b, e) body slender, molar triturative with serrate margins and tuft of setae on proximal margin; spine row consisting of 4 stout blade-like setae and slender additional setae; lacinia mobilis distally expanded, with 5 teeth; incisor with 6 stout rounded teeth; palp 3-articulate, length ratios of article 1–3: 1: 3.5: 2.9. Lower lip (hypopharynx) (Fig. 12c) with tapering distally subacute lobe and relatively short mandibular lobe. Maxilla 1 (Fig. 14a) inner plate with 10 plumose setae on medial margin, outer plate oblique with 11 distal spine-like setae with 1–3 distomedial processes; palp 2-articulate with short basal article and unknown distal article (damaged). Maxilla 2 (Fig. 14c) inner plate slightly narrower (92%) compared to outer plate, somewhat tapering distally, two rows of setae from the tip along the medial margin; outer plate subovoid with double row at apex drawing medially. Maxilliped inner plate (Fig. 14b) tapering distally, with 3 nodular setae apically, row of slender setae medially and subapically; outer plate (Fig. 14d) ovoid with serration (Fig. 15a) distomedially, row of setae along medial margin and submarginally distally; palp damaged.
PEREON. Gnathopod 1 (Fig. 15b) coxa tapering distally, apex pointed, few setae posteromarginally and some on medial face; basis slightly longer than coxa (104%), with row of short, slender setae anteromarginally and two groups of longer setae posteromarginally; ischium subquadrate; merus length 1.5× width, tapering distally, oblique apex with group of setae; carpus and propodus subequal in length with groups of setae posteromarginally; carpus with group of setae anterodistally; propodus with groups of setae on distal half of medial side; dactylus slightly curved with serrate inner curvature and distal unguis. Gnathopod 2 (Fig. 15c) similar in shape as gnathopod 1, but articles longer and coxa somewhat more bulky and with more setae on medial face. Pereopod 3 (Fig. 16a) coxa with rounded apex, weakly sinuous and with row of short setae posteromarginally; basis as long as merus and carpus combined, with setae on proximal lateral face and on both margins; ischium slightly expanded distally, slightly longer than wide; ischium to dactylus length ratios 1: 2.6: 2.1: 2.0: 1.3 and stout setae posteromarginally. Pereopod 4 (Fig. 16b–c) coxa longer than wide (116%), anteromarginally shallowly excavate; apex oblique, posterior margin with pointed process; basis as long as merus and carpus combined; ischium longer than wide, somewhat expanded distally; length ratios ischium to dactylus 1: 2.7: 2: 2.3:1.2. Pereopod 5 coxa (Fig. 17a) wider than long (119%) with wide anterior lobe and minute posterior lobe; basis anteromarginally straight, setose, posteroproximally lobate, posterodistomarginally straight, posterodistal oblique lobe; ischium subquadrate with posteromarginal notch; length ratios ischium to dactylus 1: 1.7: 2: 2.9: 1.2; merus and carpus drawn out anterodistally; ischium to propodus with robust setae along posterior margin. Pereopod 6 (Fig. 17b) similar in shape to pereopod 5, but anterior lobe of coxa smaller. Pereopod 7 (Fig. 17c) coxa slightly longer than wide (110%); basis posterior margin sinuous, posteroventral angle rounded and drawn out; length ratios ischium to dactylus 1: 2.1: 1.9: 2.5:1, shape and setation of these articles as for pereopod 5 and 6.
PLEOSOME AND UROSOME. Pleopod 1 (Fig. 16f) peduncle tapering distally; two coupling hooks on inner distal angle; rami longer than peduncle (145%), each article with a pair of long feather-like setae. Uropod 1 (Fig. 17f) peduncle weakly shorter than rami (94%), with robust setae on outer margin and a group of slender setae medioproximally; rami subequal. Uropod 2 peduncle (Fig. 17g) shorter than rami; outer ramus shorter than outer ramus (139 % of peduncle), inner ramus 2× the peduncle length. Uropod 3 (Fig. 17h) peduncle shortest; rami lanceolate, subequal in length, 2 × the peduncle length. Telson slightly longer than wide (113%), notched 24%.
Distribution (amended from De Broyer et al. 2007)
Falkland Islands: Discovery 1925–27: stn WS 81, West Falkland Island, off North Island, 81–82 m (bottom/habitat: sand; gear: nets); stn WS 85, East Falkland Island, off Lively sand; gear: nets); stn WS 85, East Falkland Island, off Lively Island, 79 m (bottom/habitat: sand, shells; gear: commercial otter trawl); stn WS 86, -53.883333°, -60.566667°, 151– 147 m (bottom/habitat: sand, shells, stones; gear: commercial otter trawl) (K.H. Barnard 1932).
Magellan Province: Puerto Condor, 90 m (bottom/habitat: rocks, ascidians); Bahia Harris, 27 m (bottom/ habitat: shells) (Schellenberg 1931); Eltanin 9, stn 740, -56.1° to -56.116667°, -66.325°, 384–494 m; Hero 715, stn 894, -54.913333° to -55.916667°, -64.3° to -64.333333°, 263–285 m (Watling & Holman 1981); Isla van der Meulen, 15 m (on hydrozoans) (this study).
Depth range
27– 494 m.
Type locality
Magellan Province: Puerto Condor, 90 m (bottom/habitat: rocks, ascidians); Bahia Harris, 27 m (bottom/ habitat: shells) (Schellenberg 1931).
Type specimen location
ZMB, Berlin.
Remarks
When compared with the type material, stored at the Museum für Naturkunde Berlin (ZMB 22838), there are a few differences in the redescribed material: (1) less pronounced depression in the middle of the dorsal carinae on pereonites and pleonites; (2) shorter middorsal and symmetrical process on urosomite 1 (vs anterior margin shorter than posterior); (3) pereopod coxa 3 proximo-posteromarginally narrower; (4) pereopod coxa 4 with a narrower ventral margin, which additionally has a weak depression; (5) colour orange with white specks (vs white with red stripes in the type description: Schellenberg 1931: 162).
The few details illustrated by K.H. Barnard (1932) of material collected off the Falklands, deviate from our material in (1) the posterior margin of pleonite 3, which has a rather straight posterior margin with a pointed tooth and a drawn out middorsal carina (vs sinuous margin with rounded protrusion and rounded middorsal hump); (2) the pointed middorsal, slightly forward curved tooth (vs straight subacute tooth) on urosomite 1 and (3) the posteroventral angles of the basis of pereopods 5–7 are drawn out acutely (vs angularly subacute).
Watling & Holman (1981) published on material collected south of the Isla de los Estados. Their drawings match our material, except for the telson, which is notched only 12% (vs 26% in our material).
description: Published as part of Coleman, Charles Oliver, Krapp-Schickel, Traudl & Häussermann, Vreni, 2022, Amphipod crustaceans from Chilean Patagonia, pp. 1-57 in European Journal of Taxonomy 849 (1) on pages 20-29, DOI: 10.5852/ejt.2022.849.1995, http://zenodo.org/record/7427542