Rhepoxynius menziesi Barnard & Barnard 1982

Rhepoxynius menziesi

Paraphoxus epistomus.—J.L. Barnard, 1960:205–209, pls. 6–8; 1964b:243; 1966a:88; 1966b:28; 1969:222; 1971:70.—Reish and Barnard, 1967:18.

Not Trichophoxus epistomus.—Bousfield, 1973:126, 127, pl. 34.2 [= R. hudsoni].

ETYMOLOGY.—Named for the late Professor Dr. Robert James Menzies, expert on Isopoda, who died in Costa Rica while exploring. He was our friend for 31 years.

DESCRIPTION OF HOLOTYPE FEMALE (female “a,” 3.19 mm).—Head about 23 percent of total body length, greatest width about 75 percent of length, rostrum constricted, narrow, elongate, reaching middle of article 2 on antenna 1. Eyes medium, partly occluded with pigment, ommatidia ordinary. Article 1 of peduncle on antenna 1 about 1.3 times as long as wide, about twice as wide as article 2, ventral margin with about 5–6 setules, weakly produced dorsal apex with 1 seta, article 2 about 0.8 times as long as article 1, with ventral narrow cycle of 8 setae, primary flagellum with 6 articles, about 0.45 times as long as peduncle, bearing several short aesthetascs in the formula 0–0–1–1–1–0; accessory flagellum with 6 articles. Spine formula of article 4 on antenna 2 = 4–3–3, dorsal margin with notch bearing 1 seta and 2 spines, ventral margin with 6 groups 1–2 long to short setae, 1 ventrodistal medium spine and 2 setules, article 5 about 0.9 times as long as article 4, facial spine formula = 2, dorsal margin bearing group of 2 setules, ventral margin with 3 sets of single setae plus setule, 2 ventrodistal long to medium spine and seta, no subdistal facial spine; flagellum about 0.8 times as long as articles 4–5 of peduncle combined, with 7 articles.

Epistomal cusp long and sharp. Mandibles with weak palpar hump, right incisor with 3 teeth, left incisor with 4 weak teeth on main hump plus large basal tooth; right lacinia mobilis simple, sharp, broad, like raker, left lacinia mobilis with 5 teeth, middle teeth shortened, right rakers 9, left rakers 7; molars composed of bulbous humps, right molar with 6 short spines plus 1 short spine strongly disjunct, left molar with 5 short spines plus 1 short spine strongly disjunct, each molar with plume; palp article 1 short, article 2 with 1 long inner apical seta and 1 other short inner seta, article 3 as long as article 2, oblique apex with 11 spine-setae, basofacial formula = 1–2 or 0–2. Each lobe of lower lip with 1 cone. Inner plate of maxilla 1 ordinary, bearing 1 medium apical pluseta, 1 shorter similar apicomedial seta, 2 apicolateral similar setae, palp article 2 with 1 apical spine and 1 apicolateral and 2 apicomedial setae and 4 submarginal setae. Plates of maxilla 2 extending equally, outer scarcely broader than inner, outer with 3 apicolateral setae, inner with 2 medial setae. Inner plate of maxilliped with 1 large thick apical spine, 3 apicofacial setae, 6 medial setae; outer plate with 5 medial spines, no apicolateral setae and cusp; palp article 1 without apicolateral seta, article 2 with 2 groups of 1–2 apicolateral setae, medial margin of article 2 moderately setose, article 3 with 2–3 facial setae, 2 lateral setae, nail of article 4 obsolescent, with one accessory setule.

Coxa 1 scarcely expanded apically, anterior margin almost straight, main ventral setae of coxae 1–4 = 10–14–11–9, posteriormost seta of coxae 1–4 slightly shortened, anterior and posterior margins of coxa 4 divergent, posterior margin oblique, almost straight, posterodorsal corner rounded, posterodorsal margin ordinary, concave, width-length ratio of coxa 4 = 5:6.

Gnathopods generally ordinary, width ratios on articles 5–6 of gnathopods 1–2 = 32:36 and 31:38, length ratios = 67:60 and 57:58, palmar humps ordinary, palms weakly oblique, article 5 of gnathopod 1 elongate, ovate, posterior margin rounded-flat, short, article 5 of gnathopod 2 elongate, ovate, posterior margin rounded, short.

Pereopod 3 stouter than pereopod 4 especially on article 4, facial setae formula on article 4=7 and 7, on article 5 = 7 and 6, main spine of article 5 extending to M. 95 on article 6, article 5 with no proximoposterior spines, spine formula of article 6 = 5 + 6 + 0 and 6 + 7 + 0 plus no middistal seta, some spines especially long; activity on inner margin of dactyls of pereopods 3–4 sharp, produced as tooth, emergent setule short, midfacial pluseta ordinary, highly distad. Coxae 5–7 posteroventral seta formula = 12–13–7. Articles 4–5 of pereopods 5–6 of ordinary width, facial spine rows sparse to moderately developed, facial ridge formula of article 2 on pereopods 5–7 = 0–1–1; width ratios of articles 2, 4, 5, 6 of pereopod 5 = 59:48:36:18, of pereopod 6 = 81:42:30:15, of pereopod 7 = 100:23:22:10; length ratios of pereopod 5 = 92:47:45:42, of pereopod 6 = 100:67:53:55, of pereopod 7 = 104:25:27:29; article 2 of pereopod 7 reaching middle of article 4, with 9 medium posterior serrations, medial apex of article 6 finely combed, bearing 2 weak digital processes.

Posteroventral corner of epimeron 1 rounded, posterior margin weakly convex, corner without setule, anteroventral margin with 4 long setae, posteroventral face with 4 long setae in oblique row. Posteroventral corner of epimeron 2 rounded, without setule sinus, posterior margin weakly convex, facial setae = 9, posteriormost pair set vertically and disjunct. Posteroventral corner of epimeron 3 weakly protuberant, without setule sinus, with 5 long setae, posterior margin short, weakly convex, smooth, ventral margin with 5 setae mainly posterior, face naked. Epimera without large seta on posterodorsal margin, epimera 2–3 with lateral ridges.

Urosomite 1 naked above base of uropod 1, articulation line almost complete, urosomite 3 unprotuberant. Rami of uropods 1–2 with articulate but tightly fixed apical nails, outer ramus of uropod 1 with 4 widely spread dorsal spines, inner with 2–3, outer ramus of uropod 2 with 2 widely spread dorsal spines, inner with 1 dorsomedial spine. Peduncle of uropod 1 with 4 basofacial setae and 1 apicolateral spine and 3 other marginal spines, medially with 4 marginal spines, apicalmost ordinary, plus 1 giant spine displaced. Peduncle of uropod 2 with 7 dorsal spines, 2 of basalmost thin and elongate, medially with 1 large apical spine. Apicolateral corners of peduncles on uropods 1–2 with comb. Peduncle of uropod 3 with 5 ventral spines, dorsally with 1 lateral spine, 1 medial setule, rami feminine, inner extending to M. 65 on article 1 of outer ramus, apex with 1 long seta, medial and lateral margins naked; article 2 of outer ramus ordinary, 0.26, bearing 2 long setae, apicomedial margin of article 1 with 2 setae, lateral margin with 3 acclivities, spine formula = 0–1–1–1, setal formula = 1–1–1–1.

Telson especially long, length-width ratio = 9:7, almost fully cleft, each apex of medium width to broad, rounded, lateral acclivities of moderate size, with short lateral and medium medial spines separated by setule, mid-lateral setules diverse, larger of large size.

Coxal gills present on segments 2–7.

MALE.–Unknown.