Epimeria rafaeli, Coleman, Charles Oliver & Lowry, James K., 2014

Coleman, Charles Oliver & Lowry, James K., 2014, Epimeria rafaeli sp. nov. (Crustacea, Amphipoda, Epimeriidae) from Western Australia, Zootaxa 3873 (3), pp. 218-232 : 220-227

Epimeria rafaeli sp. nov.

Figs 1–8

Material examined. Holotype, ovigerous female, 31 mm, Western Australian Museum, WAM C55780. Paratype, female, 27.5 mm, Australian Museum P.72997 from same locality as the holotype.

Locus typicus. Australia, Western Australia, Abrolhos, SS 10/2005/084, 29°03'39"S 113°38'10"E, 1000–1037 m, beam trawl, soft bottom, coll. Dr Stephen J. Keable, 2 December 2005.

Etymology. Named for Rafael Lowry, the wonderful little son of the second author.

Diagnosis. Rostrum straight, as long as peduncle of antenna 1. Pereon with short mid-dorsal carina. Pleon with long pointed carinae, that on pleonite 2 longest. Urosomite 1 with upright pointed process and small hump on urosomite 3. Pereopod coxa 4 elongate, almost 2 × as long as coxa 3, apex narrow, pointed and curved laterally, posteromarginal excavation shallow. Pereopod coxa 5 with long narrow spine. Pereopod 6 coxa with pointed process on lateral face. Telson with narrow notch, depth 32% of telson length.

Description. Based on female holotype, 31 mm. Body ( Fig. 1 ). Pereonites 1–6 dorsally smooth; pereonite 7 with a mid-dorsal subacute tooth. Pleonites 1–3 strongly carinate, dorsal tooth of pleonite 2 longest. Epimera 1–3 ventrally roundly produced and setose; posteroventral angle of pleonites 1–2 acutely produced, that of pleonite 3 angular. Urosomite 1 with a mid-dorsal notch (seen from laterally) and an upright pointed tooth; urosomite 2 shortest; urosomite 3 with a rounded mid-dorsal elevation.

Head. Ventral head lobe rounded ( Fig. 2a, c). Rostrum ( Fig. 2c) straight, slightly upcurved (dorsal head outline slightly concave, seen from laterally), ventral margin straight, longer than pereonite 1, reaching the apical margin of the 3rd peduncular article of antenna 1. Eye subcircular. Short mediofrontal subacute protrusion ventrally of insertions of antennae 1 ( Fig. 2c).

Antenna 1 ( Fig. 2b) peduncular article 1 longer than articles 2–3 combined (length ratios 1: 0.3: 0.2); articles 1–2 apical margin straight; accessory flagellum consisting of 1 tapering article, 1/3rd the length of 1st flagellar article; 1st flagellar article about the length of peduncular article 2, flagellum of 43 articles. Antenna 2 ( Fig. 2g) peduncular article 1 shortest, article 2 with short gland cone, not exceeding peduncular article 3; article 4 slightly longer than article 5; flagellum of 60 articles.

Upper lip ( Fig. 2d) ventrally rounded. Mandible ( Fig. 4a, c) with strong 7-dentate incisor; left lacinia mobilis 5-dentate, that of the right side narrower, blade-like and not dentate; setal row with 1 row of short and 1 row of long slender, inconspicuously serrate setae; molar slender and protruding, with a setose ridge on the anterior side; triturative molar surface bordered with acute teeth and a tuft of setae dorsally; mandibular body with group of long slender setae basally; palp 3-articulate, palp article ratios from proximal to distal 1: 2.4: 2.5; article 2 with posteromarginal setation on apical half; article 3 densely bordered with setae of variable length posteromarginally, lateral face of article 3 covered with hair-like setae. Lower lip ( Fig. 2f) with pointed mandibular processes; mediodistal regions of distally tapering lobes densely capped with wide field of short setae. Maxilla 1 ( Fig. 3c) inner plate ovoid, with 12 stout plumose setae along the medial margin and some short setae subapically; outer plate obliquely truncate with 11 medially serrate spine-like setae, except for second one (counted from medially), which is bifid; palp 2-articulate, basal article with oblique distal margin, article 2 about 3 × article 1 length, slightly curved inwards, apically serrate with insets of robust setae and additional subapical slender setae. Maxilla 2 ( Fig. 3a) inner lobe shorter and wider than outer, with setae along medial margin, shorter than those on outer plate; outer plate with a row of short slender setae and a row of long stout setae, which are medioapically serrate. Maxilliped ( Figs 2h, 3b, d, e), inner plate reaching the length of the distal medial angle of palp article 1, apically with short setae and 3 nodular setae apicomedially and long setae along the medial margin; outer plate ovoid, surpassing half of palp article 2, distal margin with slender and distomedial margin with especially robust setae; distomedial region step-like produced with a submarginal row of short setae; palp 4-articulate; article 1 with oblique distal margin; article 2 longest; article 3 half as wide as article 2; article 4 slightly curved, inner margin bordered with small teeth, with narrow unguis apically.

Pereon. ( Fig. 1 , 2a) Pereopod 1–3 coxae successively longer with ridge-like elevated lateral face; coxa 4 about 2 × the length of coxa 3, apex curved laterally; coxa 5 with long, slender, pointed process, directed posterolaterally.

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a b c a b c Gnathopod 1 ( Fig. 4b, d) coxa somewhat concave anteromarginally, tapering distally, apically rounded, posteromarginally slightly convex; basis longer than coxa, slightly curved anteriorly, bordered with setae anteromarginally and with some long slender setae posteromarginally; ischium slightly wider than long; merus pointed distally, with longitudinal articulation of carpus; carpus distally slightly expanded with groups of posteromarginal setae; propodus 0.8 × carpus length, setation in groups especially on medial face; palm convex, with fine serration and several robust setae at the end palm, dactylus weakly curved with row of slender teeth on inner curvature, slender unguis apically. Gnathopod 2 (Fig. a, b) coxa of similar shape and basis to merus subequal to gnathopod 1, carpus and propodus of similar length and setation to gnathopod 1, but narrower; dactylus as for gnathopod 1. Pereopod 3 ( Fig. 5c) coxa tapering distally, apically rounded, posterior margin with round protrusion and notch dorsal to insertion of basis; basis subrectangular, setose on anterior margin and groups of setae posterolaterally; ischium as wide as long with rounded anterior margin; merus slightly curved posteriorly, without robust setae; carpus and propodus with groups of robust setae posteromarginally; length ratios of merus to propodus 1: 0.7: 0.8; dactylus weakly curved with terminal unguis. Pereopod 4 ( Fig. 6a, b) coxa strongly extended ventrally, with an elongate, slightly posteriorly and laterally curved apex, posterior margin excavate and with rounded lobe at proximal third; basis weakly expanded distally with setation along anterior margin and groups of setae at lateral face close to posterior margin, 1 group of the setae with especially long setae, distal margin densely setose; ischium about as long as wide, anterior margin rounded; merus without robust setae; on right body side carpus to dactylus deformed, shortened and void of almost all setae; on left side normally developed, carpus and propodus with groups of robust setae posteromarginally; length ratios of merus to propodus 1: 0.7: 0.8; dactylus weakly curved with terminal unguis. Pereopod 5 ( Figs 6c, 7a) coxa with elongate posterior process; basis elongate with ridge on lateral face and additional ridge close to posterior margin, short angular process on posteroproximal margin and posteroventral rounded lobe, partly covering ischium; on right appendage ( Fig. 7a) ischium to dactylus deformed and void of setae (except for a very long one on ischium); left appendage normally developed ( Fig. 6c), ischium wider than long, distally lobate; merus slightly curved anteriorly, without robust setae; carpus and dactylus with robust setae anteromarginally; length ratios of merus to propodus 1: 0.9: 1.2; dactylus weakly curved with terminal unguis. Pereopod 6 ( Figs 7b–d) on right body side deformed; on left side normally developed; coxa longer than wide with a pointed lobe on the lateral face; basis similar in shape and setation as on pereopod 5, but wider; ischium distally lobate; merus to dactylus as for pereopod 5, length ratios of merus to propodus 1: 0.9: 1.2; dactylus weakly curved with terminal unguis. Pereopod 7 ( Fig. 8a) coxa longer than wide; basis wider than those of preceding appendages, ridge on lateral face, anterior margin weakly setose, posterior margin lobate, posteroventral lobe partly covering ischium; ischium wider than long; merus to propodus with groups of robust setae anteromarginally, length ratios 1: 1: 1.2; dactylus weakly curved with terminal unguis.

Pleon. Pleopod 1 ( Fig. 8d) peduncle 2.5 × as long as wide with some long setae medioproximally and some shorter setae laterodistomarginally, 2 coupling hooks; outer ramus longer than inner with the usual set of plumose setae on both margins.

Urosome. Uropod 1 ( Fig. 8c) peduncle subrectangular with small robust setae along the lateral margin; outer ramus slightly shorter than inner; inner ramus 1.1 × the length of the peduncle. Uropod 2 ( Fig. 8b) peduncle weakly expanded distally, with short robust setae lateromarginally; inner ramus 2.2 × the length of peduncle, outer ramus shorter than inner ramus. Uropod 3 ( Fig. 8e) peduncle shortest, with pointed distal process, rami subequal in length. Telson ( Fig. 8f) 1.2 as long as wide, rather narrowly notched 32%, apices subangular, 2 plumose short setae each on both margins.

Distribution. Only known from type locality. This is the first Epimeria species from Western Australia.

Figures

FIGURE 1. Epimeria rafaeli sp. nov., holotype, female 31 mm. Habitus. Scale bar = 5 mm.