Epimeria colemani Souza-Filho, Guedes-Silva & Andrade, 2024

Souza-Filho, Jesser F., Guedes-Silva, Elkênita & Andrade, Luiz F., 2024, Four new species and two new records of deep-sea Amphipoda (Crustacea: Peracarida) from Potiguar Basin, north-eastern Brazil, Journal of Natural History 58 (41 - 44), pp. 1615-1655 : 1634-1639

Epimeria colemani Souza-Filho, Guedes-Silva & Andrade sp. n.

( Figures 12–16 )

Material examined

Holotype female (ovigerous), 33.8 mm, Potiguar Basin , MT 73–2 , initial trawl coordinates 4.6475°S, 36.5001°W, final trawl coordinates 4.6434°S, 36.4693°W, Rio Grande do Norte state, Brazil, initial depth 955 m, final depth 1006 m, 16 May 2011, R / V Seward Johnson col. ( MOUFPE 15084 ).

Type locality

Slope of Rio Grande do Norte state, north-eastern Brazil, between 4.6475°S, 36.5001°W and 4.6434°S, 36.4693°W.

Diagnosis

Rostrum evenly curved downwards, as long as peduncle of antenna 1. Pereonite 7 with a short mid-dorsal carina. Coxa 4 elongated, almost 1.5× as long as coxa 3, apex narrow, pointed and curved laterally, posteromarginal excavation shallow. Coxa 5 with narrow spine distally curved upwards. Coxa 6 with pointed process on lateral face. Gnathopods 1–2 palm almost transverse. Pereopods 3–7 dactylus with a nail. Pleon with long pointed carinae, that on pleonite 2 longest. Urosomite 1 with upright pointed process and small hump on urosomite 3. Telson with a shallow notch.

Description

Based on female holotype, 33.8 mm, MOUFPE 15084. Body as in Figure 12 . Head ( Figure 12a ) rostrum reaching the apex of peduncular article 3 of antenna 1; eyes subtrapezoidal. Antenna 1 ( Figure 12b ) peduncle article 1 about 1.7× longer than wide; accessory flagellum 1-articulate. Antenna 2 ( Figure 12c ) longer than antenna 1, peduncle article 4 about 1.3× longer than article 5; flagellum 44-articulate. Lower lip ( Figure 12d ) inner and outer margins setose. Mandibles ( Figure 12e –) incisors with 5 teeth; molar triturative; left lacinia mobilis with 7 teeth; right lacinia mobilis with a smooth ridge and a blunt projection; accessory setal row with many plumose between robust multicuspidate setae; palp 3-articulate, article 2 about 1.3× the length of article 3, article 3 setose. Maxilla 1 ( Figure 12g ) inner plate with plumose setae; outer plate with 9 robust serrate setae; palp 2-articulate, article 2 apex with 5 acute projections, bearing 4 robust setae. Maxilla 2 ( Figure 12h ) inner and outer plates setose, with facial setules. Maxilliped ( Figure 12i ) inner plate with 3 short robust apical setae; outer plate broad, mesial margin with a finely serrate ridge, apically with robust and slender setae; palp article 2 setose, article 4 mesial margin serrate, with an apical nail.

Coxae 1–3 ( Figures 14a–b , 15a ) much deeper than wide, increasing in length. Gnathopod 1 ( Figure 14a ) basis curved, anterior margin setose; merus posterior margin setose, 1.2× longer than propodus; propodus 2.1× longer than wide, posterior margin with groups of slender and robust setae; palm, finely serrate; dactylus longer than palm, serrate, with a nail. Gnathopod 2 ( Figure 14b ) basis anterior margin setose; carpus slightly longer than propodus; palm finely serrate; dactylus longer than palm, serrate, with a nail. Pereopods 3–4 ( Figure 15a–b ) similar, slender, merus longer than carpus and propodus. Pereopods 5–6 ( Figure 15c–f ) similar, slender, weakly setose. Pereopod 7 ( Figure 15f ) basis 1.8× longer than wide, posterior margin with a strong medial broadening; carpus as long as propodus. Pereonites 1–6 ( Figure 1 ) dorsally smooth; pereonite 7 ( Figure 16b ) with a short mid-dorsal subacute tooth. Pleonites 1–3 ( Figure 16c–e ) strongly carinate, dorsal tooth of pleonite 2 ( Figure 16d ) longest; pleonites 1–2 ( Figure 16c–d ) posteroventral corner acutely produced, that of pleonite 3 ( Figure 16e ) angular. Epimera 1–3 ( Figure 16c– e ) ventrally rounded, produced. Urosomite 1 ( Figure 16f ) with a mid-dorsal notch (seen from lateral) and an upright pointed tooth; urosomite 2 ( Figure 16g ) being the shortest; urosomite 3 ( Figure 16H ) with a rounded mid-dorsal elevation. Uropod 1 ( Figure 16o ) peduncle 5.4× longer than wide, with 2 dorsal rows of short robust setae; rami subequal with a continuous row of short robust setae. Uropod 2 ( Figure 16p ) peduncle 2.5× longer than wide, with dorsal short robust setae; outer ramus short than inner, with marginal short robust setae; inner ramus damaged. Uropod 3 ( Figure 16q ) peduncle 2.1× longer than wide; rami subequal, lanceolate, with marginal short robust setae. Telson ( Figure 16r ) subtrapezoidal, with a shallow notch of about 10% the whole length.

Variations

It is important to highlight that the shape of the coxa 5 of the holotype presents a variation on left and right sides. The right coxa 5 ( Figure 15d ), which is figured on the habitus, shows a higher degree of curvature on its distal part, whereas the left side, although curved, is not as strong.

Etymology

The specific epithet is dedicated to Dr Charles Oliver Coleman, for his great contribution to the taxonomy of amphipods and to the genus Epimeria .

Distribution and bathymetry

Known only from the type locality (slope of Rio Grande do Norte state, north-eastern Brazil, 4.6475°S, 36.5001°W and 4.6434°S, 36.4693°W), between 955 and 1006 m deep ( Figure 23 ).

Remarks

Among the known species of the genus, E. colemani sp. n. is most similar to E. ultraspinosa Wakabara and Serejo, 1999 and E. norfanzi Lörz, 2011 in presenting coxa 5 with a long spiniform process and pleonites 1–3 with well-developed dorsal spiniform process. However, the new species can be distinguished from E. ultraspinosa by the following characters (characters of E. ultraspinosa in parentheses): mandible palp article 2 about 1.3× longer than article 3 (slightly longer); pereonites 6–7 with a dorsal process (without process); coxa 4 posterior lobe blunt (acute); coxa 5 measurement from anterior margin to distal end of spiniform process 1.8× longer than basis length (2.9× longer), distally curved upwards (straight); gnathopod 1 palm almost transverse (acute); uropods 1–2 rami not reaching the apex of uropod 3 rami (reaching the apex). Epimeria colemani sp. n. also differs from E. norfanzi by the following (characters of E. norfanzi in parentheses): rostrum directed downward and reaching the end of peduncle article 3 of antenna 1 (directed straight forward and reaching the end of peduncle article 1); coxae 1–3 ventral corner acute (blunt); coxa 5 spiniform process broad, curved upwards (thin, curved downwards); pleonite 3 dorsal process large, projecting distally (short, projecting medially), telson notched (entire).

Figures

Figure 1. Adeiella debroyeri sp. n., female holotype, 28 mm (MOUFPE 20192). Habitus. Scale bar: 5 mm.

Figure 12. Epimeria colemani sp. n., female holotype 33.8 mm (MOUFPE 15084). Habitus. Scale bar: 5 mm.

Figure 13. Epimeria colemani sp. n., female holotype 33.8 mm (MOUFPE 15084). A, head; B, antenna 1 inner margin; C, antenna 2 inner margin; D, lower lip; E, left mandible; F, right mandible; G, maxilla 1; H, maxilla 2; I, maxilliped. Scale bars: A = 2 mm; B, C, I = 1 mm; D–H = 0.5 mm.

Figure 14. Epimeria colemani sp. n., female holotype 33.8 mm (MOUFPE 15084). A, gnathopod 1; B, gnathopod 2. Scale bars: 1 mm.

Figure 15. Epimeria colemani sp. n., female holotype 33.8 mm (MOUFPE 15084). A, pereopod 3; B, pereopod 4; C, right pereopod 5; D, left coxa 5; E, pereopod 6; F, pereopod 7. Scale bars: 1 mm.

Figure 16. Epimeria colemani sp. n., female holotype 33.8 mm (MOUFPE 15084). A, pereonite 6; B, pereonite 7; C, pleonite/epimeron 1; D, pleonite/epimeron 2; E,pleonite/epimeron 3; F, urosomite 1; G, urosomite 2; H, urosomite 3; I, pereonite 5 (dorsal); J, pereonite 6 (dorsal); K, pereonite 7 (dorsal); L, pleonite 1 (dorsal); M, pleonite 2 (dorsal); N, pleonite 3 (dorsal); O, uropod 1; P, uropod 2; Q, uropod 3; R, telson. Scale bars: A–N = 2.5 mm; O–Q = 1 mm; R = 0.5 mm.

Figure 23. Map showing local distribution of the species recorded in the present paper from Potiguar Basin, Rio Grande do Norte state, Brazil.